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Using Longitudinal Data to Understand Children's Activity Patterns in an Exposure Context: Data from the Kanawha County Health Study
Abstract
An important component of assessing the levels, the sources, and the health effects of children's exposure to air pollution is understanding how and where members of this sensitive population spend their time. There are, however, few data bases that allow the documentation of the day-to-day nature of children's activities. Of particular concern is whether the one-day snapshots provided by time/activity diaries typically used in exposure studies represent the actual temporal and spatial extent of children's activities. As part of a community health study, longitudinal data on children's time/activity patterns were recently collected. A respiratory health status and gender stratified sample of 90 children kept daily diaries over two-week periods during both the summer and the fall. This paper first presents baseline information of children's activity patterns: the sample distribution of time spent in each of five microenvironments (travel, outdoor, at school, at home, and inside other locations) and the daily temporal pattern of activities. The consistent patterns of children on school days suggest that for most days we can accurately predict children's locations by time of day. The second part of the analysis shows that there is both high child-to-child variation in the average time spent in each microenvironment, even after controlling for gender and respiratory health status, and strong temporal variability in activity patterns within a child over time, even after controlling for school days versus nonschool days.
... The authors found that approximately 50% of the sample visited narrowly defined MEs on only one day of the two sampled, and that the daily difference in daily time spent between the two days was about equal to the average time spent in these MEs (Schwab et al., 1990). Many of the same researchers conducted a longer activity/ location study in 4th–6th grade children as part of a prospective epidemiological study in Kanawha County West Virginia (Schwab et al., 1992). The analyzed sample focused on children having at least 12 consecutive days of activity diary data in one of two seasons: 62 children in the nonschool period (July) and 72 in the school period (September). ...
... Girls and boys differed significantly only in the time spent outdoors; boys spent more time there on both school and non-school days. Asthmatics did not differ significantly from non-asthmatics in the time spent in any ME, including outdoors (Schwab et al., 1992 ). Withinchild differences were considerable for some ME's, especially on non-school days. ...
... ies; outdoor and non-home ME's exhibited the most active exertion levels (Schwab et al., 1991). There was significant between-child variability in the time spent in moderate and vigorous exertion, and there were weekend versus weekday differences also. The within-child variance in moderate/vigorous activities was considerable (Schwab et al., 1991). Schwab et al. (1992) also present an analysis of how many days of locational data are required from a child to reduce the proportion of daily mean-time ME mis-classifications on a quartile basis. The aim of their analysis was to place a child into her or his correct mean-time quartile of the sample distribution using as little daily data as possible. A ''gr ...
This paper summarizes a series of analyses of clustered, sequential activity/location data collected by Harvard University for 160 children aged 7-12 years in Southern California (Geyh et al., 2000). The main purpose of the paper is to understand intra- and inter-variability in the time spent by the sample in the outdoor location, the location exhibiting the most variability of the ones evaluated. The data were analyzed using distribution-free hypothesis-testing (K-S tests of the distributions), generalized linear modeling techniques, and random-sampling schemes that produced "cohorts" whose descriptive statistical characteristics were evaluated against the original dataset. Most importantly, our analyses indicate that subdividing the population into appropriate cohorts better replicates parameters of the original data, including the interclass correlation coefficient (ICC), which is a relative measure of the intra- and inter-individual variability inherent in the original data. While the findings of our analyses are consistent with previous assessments of "time budget" and physical activity data, they are constrained by the rather homogeneous sample available to us. Owing to a general lack of longitudinal human activity/location data available for other age/gender cohorts, we are unable to generalize our findings to other population subgroups.
... Sex. Sex has been identified as a factor influencing activity level and the types of behaviors and activities in which children participate (27)(28)(29). As early as preschool (3-5 years of age), sex differences exist in the types of games played, the frequency of play, and activity level. ...
... Locations in which children spend time also vary by sex. Clear differences in the frequency and type of outdoor activities have been found between boys and girls 7-15 years of age (29,30). Boys are more likely than girls to play outdoors, and the character of their activity is different from girls. ...
... Indoor air pollution has become a particular problem since the energy crisis of the 1970s, which led to the construction of more energy-efficient buildings with less air circulation. In the United States, most children spend the majority of each day inside buildings [20]. Many allergens and irritants can be found indoors [20,21]. ...
... In the United States, most children spend the majority of each day inside buildings [20]. Many allergens and irritants can be found indoors [20,21]. Table 1 summarizes the epidemiologic studies showing an association between air pollution and asthma prevalence or morbidity in Asian countries. ...
Background: There is growing evidence suggesting that air pollution is responsible for the increasing prevalence of asthma in Asia. Exposure to indoor or outdoor air pollutants in communities is relevant to the acute exacerbation as well as the prevalence of asthma. Air pollutants emitted from coal combustion in households may exceed those from industrial resources, and control of such air pollution is of great public health importance. Tobacco smoke is prevalent in Asia and partly responsible for asthma morbidities, despite growing awareness of its adverse respiratory effects. Methods/Data base: A review of the literature. Results: In some Asian studies, respiratory symptoms were found to be more prevalent in individuals living near busy roads than in those whose residence was exposed to larger amounts of pollen allergens and less traffic. This suggests that air pollution could be a risk factor for asthma in addition to atopy. Ambient air pollutants at current levels have been shown to have a harmful effect on more susceptible people in several countries. It is possible that the permissible levels of air pollutants are not sufficiently low for the protection of human health. Because cross-sectional studies cannot confirm a causal relationship for various asthma morbidities, the association with known air pollutants remains suggestive. Conclusions: More carefully designed long-term studies are needed to document the causal effects and dose-response relationship between various air pollutants and asthma. Better technology and public policy are needed to help prevent the enormous suffering and human loss associated with air pollution. What has yet to be documented is whether reduced indoor and outdoor pollution will result in decreased asthma morbidity. Studies to investigate this hypothesis are currently under way.
... Time-activity data are an essential component of risk assessment models aiming to estimate exposure to contaminants in the environment. Traditionally, the collection of time-location/activity data has relied on retrospective telephone surveys ( Klepeis et al., 2001;Leech et al., 2002;Abraham et al., 2006;Robinson and Martin, 2009) or paper diaries, either filled out retrospectively or contemporaneously ( Schwab et al., 1992;Echols et al., 1999;Freeman et al., 1999;Schweizer et al., 2007;Nethery et al., 2009), which are labor-intensive and costly. Lately, Global Position System (GPS) recording devices have been used to collect time-use information ( Elgethun et al., 2003;Wiehe et al., 2008;Vazquez-Prokopec et al., 2009). ...
... The number of location-activities reported per day and the number of location changes per day were used as indicators of survey compliance or accuracy of reporting on days with a very busy schedule rather than omitting activities and locations that take time to report (Schwab et al., 1992). ...
Time-activity data are traditionally collected by telephone interviews or through paper diaries, which are time consuming and costly. As a potential alternative that may greatly save staff time, a web survey to collect time-activity data was developed and tested in this study. We collected 24-h recall web diaries from 151 parents of young children mostly under 55 years of age (who also answered for their children) and 55 older adults (≥ 55 years of age) both on a weekday and a weekend day every 3 months during an 18-month period. The performance and reliability of the web surveys collected were evaluated, including the survey-completion rate, and the percentage of surveys with unreasonable time being reported as spent sleeping and with missing reports of being in transit between locations. We also compared the web-survey data with time-activity information we collected from the same subjects in telephone interviews and found that these data sources were fairly consistent with each other. However, we observed slightly more compliance issues for the web than the telephone survey, but most of these issues could be addressed and minimized by refining some questions or the survey interface. Our study suggests that it is critical to reduce participants' burden and improve survey interface design for optimal compliance and data quality. In conclusion, web surveys are a promising method to consider for time-activity data collection.
... Children, as a subset of the population, are of particular concern when investigating exposures to environmental pollutants because of their frequent hand and mouthing behaviors California Air Resources Board, 1991;Schwab et al., 1992;Eckerman, 1994;Lewis et al., 1994). Because of these contact and mouthing activities, children may have high exposures to dust-laden pollutants such as lead and pesticides through dermal contact or ingestion. ...
... Despite the fact that children may be at increased risk because of exposure to many compounds in the environment, most available activity pattern data focus on adult populations and general activities such as time spent indoors or in transit (Moschandreas and Relwani, 1990;California Air Resources Board, 1991;Schwab et al., 1992). The lack of studies focusing on children's hand-tomouth activities may be due to difficulties associated with obtaining reliable data from children or their parents through traditional methods such as questionnaires and diaries (Medrich, 1982). ...
A videotaping methodology has been developed for use in quantifying the types and frequencies of children's hand and mouthing activities that could lead to exposure to environmental pollutants via dermal and ingestion pathways. Twenty children in day care, ages 3-6 years and 10 children in residences, ages 2-5 years, were videotaped during their waking hours for 1 day. Parents of each child completed questionnaires for the purpose of evaluating the accuracy of parental reports of hand-to-mouth rates. Videotapes were translated as quantifiable activities by two trained observers whose reporting reliability was checked throughout the investigation. Results determined that reliability of the videotaping method was very good, even over a year post-training. From videotape data, the average hand-to-mouth frequency rate was determined to be 9.5 contacts/h. These values are considerably higher than the current default value of 1.56 contacts/h under consideration by the EPA.
... Longitudinal microenvironmental time budget data were obtained from a study of children's exposure to air pollutants in the Kanawha Valley, West Virginia (Schwab et al., 1992). This study was conducted over a 4-week period in 1989 (2 weeks during the summer and 2 weeks in the fall) during which 90 school age children reported daily time spent in various indoor and outdoor activities at home and school. ...
... Boys were found to spend significantly more time outdoors than girls. The study also concluded that among days of the week, children exhibit significant variability of time spent in transit and outdoors (Schwab et al., 1992). For example, 10% of the population reported an average of 0.7 h per day outdoors on weekdays, while 10% reported an average of greater than 4.0 h during the same time span. ...
Information on human time-activity patterns is often required to interpret environmental exposure data fully and to implement exposure assessment models. Data on short-term time-activity patterns for individuals, such as 1-day measurements, are relatively abundant. The reliability of such data for use in chronic exposure (e.g., 1 or more years) assessments performed for evaluation of health risks is not well understood. As part of the NHEXAS-Maryland investigation, daily time budget data for seven microenvironments were collected from 80 people during as many as six 1-week Cycles over a 12-month period. The data were summarized and analyzed statistically by sampling Cycle, day of week, and individual to characterize long-term average microenvironmental time budgets and to identify their determinants. Median times spent in transit, indoors at home, outside at home, indoors at work or school, outdoors at work or school, indoors at other locations, and outdoors at other locations were found to vary significantly, although not substantively in many cases, by time of year (i.e., Cycle), by day of week, and by individuals. Time budgets for most of the microenvironments also exhibited significant variability by gender, age group, education level, annual household income, and work status. The results indicate that short-term (e.g., 1-day) measures of microenvironmental time budgets for individuals are unlikely to be representative of their long-term patterns. Thus, health risk or epidemiological assessments performed for a population mean or specific quantile may be relatively insensitive to when time budget data were collected. However, the accuracy of such assessments performed for individuals is likely to be greatly improved by collection of time budget data from numerous points in time.
... The analyses indicate that high day-to-day correlations in the time spent in even aggregated locations by an individual do not exist in general, contrary to what might be expected. While this may be a peculiar finding of the individual being analyzed, it is consistent with other correlation analyses seen in the literature ( Schwab et al., 1990Schwab et al., , 1991Schwab et al., , 1992MacIntosh, 2001;Xue et al., 2003). ...
... times per year for 1283 adults using 30-min block diaries. Within-person variability is large for some location/activity events Schwab et al. (1990) Schwab et al. (1992) #=Male; ~=female. a Usually shown to be statistically significant in quantitative analyses, but often is used simply as a qualitative descriptor of organized data (without being tested for statistical difference). ...
This paper tests factors thought to be important in explaining the choices people make in where they spend time. Three aggregate locations are analyzed: outdoors, indoors, and in-vehicles for two different sample groups: a year-long (longitudinal) sample of one individual and a cross-sectional sample of 169 individuals from the US Environmental Protection Agency's Consolidated Human Activity Database (CHAD). The cross-sectional sample consists of persons similar to the longitudinal subject in terms of age, work status, education, and residential type. The sample groups are remarkably similar in the time spent per day in the tested locations, although there are differences in participation rates: the percentage of days frequenting a particular location. Time spent outdoors exhibits the most relative variability of any location tested, with in-vehicle time being the next. The factors found to be most important in explaining daily time usage in both sample groups are: season of the year, season/temperature combinations, precipitation levels, and day-type (work/nonwork is the most distinct, but weekday/weekend is also significant). Season, season/temperature, and day-type are also important for explaining time spent indoors. None of the variables tested are consistent in explaining in-vehicle time in either the cross-sectional or longitudinal samples. Given these findings, we recommend that exposure modelers subdivide their population activity data into at least season/temperature, precipitation, and day-type "cohorts" as these factors are important discriminating variables affecting where people spend their time.
... Regarding children that share the same room, we can understand that separate rooms decrease the possibility of contamination, especially in pediatric and respiratory diseases [7,9] Solid biomass fuel for cooking and heating, exposes many children to high levels of indoor air pollution and it is significantly associated with decline in lung function and higher prevalence of asthma in children [6]. Also since children spend nearly 20 hours per day indoors, indoor air quality became more important because of its potential effects on asthma [10]. This is mainly because children are more sensitive to environmental factors than adults, since they are still developing and growing, hence they are not yet able to cope with pollutants, and they also eat, drink and breath morein comparison to their body mass-so they are more vulnerable to environmental pollutants than adults [11]. ...
Aim: The aim of the study was to investigate the effect of physical activity and indoor environment on preschool children’s health. Subject and Methods: The final sample comprised 126 parents of children of preschool age. An anonymous questionnaire was used in order to investigate the impact of indoor air pollution on the children's health. Data analysis was performed by using descriptive statistics and cross-tabulations with the SPSS 22.0. Results: The majority of the parents were female (87.3%) at an average age of 31-40 years (73%). Regarding the children, there were an almost equal number of boys and girls and their age ranged between 3 and 6 years old. The children had not shown any signs of emotional or behavioural problems or other issues regarding regular physical functions and they hadn’t shown any problems regarding recreational activities and interaction with friends (90.5%). Cough is a frequent symptom in the case of a common cold (85.7%). There were no statistically significant differences in the parents' responses as far as their children's health dimensions, concerning the availability of an air conditioner at home, the existence of pets and smoking habits in the family environment. Conclusions: Improving air quality is an extremely complicated issue, since pollutants may be created both indoors and outdoors, which makes it very difficult to decrease them. Yet it still is definitely necessary, given the negative effects of pollution on human health, especially on the more vulnerable groups, such as children.
... However, some schools are located on or dangerously close to environmental hazards such as Toxic Release Inventory (TRI) sites that threaten the health and safety of schoolchildren as well as teachers, administrators, and others who work at schools (Salvesen et al., 2008). Consequently, school locations represent one of the most important spatial factors to be considered in environmental exposure analysis (Schwab et al., 1992). They can also be a key determinant of exposure to toxic pollutants for schoolchildren because they spend most of their daytime at school. ...
Previous research on environmental justice has demonstrated a disproportionate burden of environmental hazards on low-income and minority residents. This study uses statistical and GIS analysis methods to examine whether, in Boston, there are disparities in the proximity of public schools to Toxics Release Inventory sites based on school-level characteristics, such as schoolchildren’s racial and socio-economic statuses, educational resources and academic achievements. Research results show that schools with high percentages of minority (i.e. Black schoolchildren) and economically disadvantaged schoolchildren are more likely to be located closer to Toxics Release Inventory sites in Boston, indicating the existence of an environmental injustice issue in the city. In addition, schoolchildren in the schools located closer to Toxics Release Inventory sites tend to have lower academic performance. This research suggests that special attention should be given to unequal exposure of public schools to hazardous sites in Boston and calls for decision makers to spend scarce funds on promoting environmental justice. Such changes could have positive effects on schoolchildren’s academic achievements.
... Given these results, we do not believe that participant fatigue would greatly influence the longitudinal time use data analysis results reported in subsequent sections. This finding is consistent with data presented in Glorieux & Minnen (26) and Schwab et al. (27), but "respondent fatigue" has been observed in other longitudinal diary studies (28). ...
Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal of improving the parameterization of human activity algorithms in EPA's exposure modeling efforts. Despite the longitudinal, multi-season nature of the study, participant non-compliance with the protocol over time did not play a major role in data collection. The diversity (D)-a ranked intraclass correlation coefficient (ICC)-and lag-one autocorrelation (A) statistics of study participants are presented for time spent in outdoor, motor vehicle, residential, and other-indoor locations. Day-type (work-day versus non-workday , and weekday versus weekend), season, temperature, and gender differences in the time spent in selected locations and activities are described, and D & A statistics are presented. The overall D and ICC values ranged from approximately 0.08-0.26, while the mean population rank A values ranged from approximately 0.19-0.36. These statistics indicate that intra-individual variability exceeds explained inter-individual variability, and low day-today correlations among locations. Most exposure models do not address these behavioral characteristics, and thus underestimate population exposure distributions and subsequent health risks associated with environmental exposures.
... Indoor air hazards, while recognized as a problem of major concern (Habre et al. 2014a), remain less well characterized. On average, children spend up to 20 h per day indoors (Franklin, 2007, Schwab et al. 1992. While infiltration of outdoor air pollution does significantly contribute to the indoor environment, our previous analysis in these inner-city data indicate that~72% of PM 2.5 mass in these homes likely originated from indoor sources (Habre et al. 2014b). ...
Indoor air pollution is increasingly recognized as a significant risk for respiratory illness, particularly in vulnerable populations. Thirty-six children aged 6–14 years with moderate/severe asthma from inner city areas in New York City were studied for 2-week periods (summer and winter) using diaries and spirometry. Seven-day integrated indoor samples of PM10, PM2.5, trace elements, elemental/organic carbon, black carbon, and criteria gases (NO2, SO2, and O3) were collected in the subjects’ residences. Asthma outcomes included cough and wheeze severity, albuterol use, and pulmonary function. Mixed effects regression models for longitudinal data were used to relate weekly indoor pollutant concentrations to asthma outcomes. Odds ratios (ORs) were calculated for ordinal outcomes. During winter, significant positive associations for average weekly symptom severity scores were seen for NO2 (OR = 2.83; p = 0.02), calcium (OR = 3.29; p = 0.02), and silicon (OR = 3.64; p = 0.04). In summer, chlorine was associated with average weekly symptom scores (OR = 1.85; p = 0.004). Average albuterol puff use per day in winter was associated with NO2 (OR = 5.89; p = 0.009), nickel (OR = 2.27; p = 0.05), and silicon (OR = 5.59; p = 0.05). Albuterol use was not associated with indoor pollutants in summer. Asthma severity was associated with specific indoor pollutants. Seasonal differences were observed by pollutant and by clinical index studied.
... Children living in urban areas spend more than 90% of their time in specific microenvironments, such as home, school and urban transport. Results reported in a health study conducted in West Virginia, among 100 sixth graders, indicate that children spent on average 14.0 h at home, 5.8 h at school and 0.7 h on travel (Schwab et al., 1992). Silvers et al. (1994) conducted a children's activity survey in U.S.A. in varied geographic regions. ...
... Good indoor air quality is important for all of us; most people spend 90% or more of their time indoors (Schwab et al., 1992), where they are exposed to some indoor environmental factors (bio-aerosol) that influence their health and physical condition. Therefore there has been a growing interest in indoor microbe studies in recent years (Shruti et al., 2011;Shiferaw et al., 2013). ...
According to the U.S. Environmental Protection Agency (EPA), the average population spends nearly 90% of their time at indoors; consequently, the EPA considers indoor air pollution a high priority health risk. In this study, we compare indoor microbial distribution pattern in rural vs urban areas of meerut region. A Very intensive bacterial growth was observed in the kitchen sections compare to living room area of both urban and rural area. Moreover, an interesting result was also observed in kitchen section. The kitchen of urban area was significantly less contaminated than rural kitchen. Qualitative Analysis of Air in the all sampling sites Microbiological quality of indoor air is created not only by a total concentration of bacteria and fungi but by the presence of some particular microorganism species, which is very important for the human health. The predominant bacterial group and moulds isolated from investigated air samples were: Brevundimonas diminuta; Bacillus megaterium; Bacillus Subtilis; Bacillus ceres, Enterococcus, streptobacillus, Klebsiella pneumoniae; Pseudomonas aeruginosa, Citrobacter freundii and Alternaria spp., Mucur spp., Cladosporium spp., Aspergillus Spp. This result indicates that neither proper cleaning was happened nor air ventilation was maintained in both urban and rural areas.
... [6] Because many young children spend a long time inside their houses, they may have significant exposure to environmental tobacco smoke there. [7] The adverse effects of such exposure were well documented in many countries, including the Sudan. [8][9][10][11][12] Passive smoking causes increased incidence of respiratory tract infections, asthma, impaired lung function, middle ear problems, sudden infant death syndrome, altered lipid profile, and childhood cancers. ...
... In 2007, the U.S. Centers for Disease Control and Prevention reported that 1 in 13 school-aged children have asthma in the United States [28]. Since children spend nearly 20 h a day indoors [35], indoor air quality received an increased level of public concern because of its potential effects on asthma. The U.S. Environmental Protection Agency has designated indoor air pollution as one of the top environmental risks to public health [39]. ...
An air cleaning/ventilating window unit was designed to improve air quality and health in asthmatic children. The unit, which provides 9 air changes per hour (ACH) with 1.7 fresh ACH through a 95% efficient particulate matter filter, was tested for 14 weeks in the bedrooms of twenty asthmatic children between ages 5 and 16. During the first six week period, the unit was installed with a placebo filter. The unit was turned off for the next two weeks. During the last six weeks of testing, the unit was fully functional with the outside air intake and exhaust fan running and filter in place. Indoor air quality parameters were monitored for each operational mode in each home. To evaluate pulmonary inflammation, peak expiratory flow (PEF) was measured and an exhaled breath condensate (EBC) sample was collected every sixth day and analyzed for nitrate. Measurements of indoor air quality and pulmonary function showed statistical improvement with the unit running as compared with the placebo mode both with and without ventilation.
... Children represent one of the most vulnerable groups of a society with regard to potentially harmful effects induced by air pollution (Schüepp and Sly 2012;WHO 2010). In their earliest years, children stay mostly indoors with significant amount of time spent at preschools (Schwab et al. 1992). Nevertheless, there is only little information concerning PAHs in schools. ...
As children represent one of the most vulnerable groups in society, more information concerning their exposure to health hazardous air pollutants in school environments is necessary. Polycyclic aromatic hydrocarbons (PAHs) have been identified as priority air pollutants due to their mutagenic and carcinogenic properties that strongly affect human health. Thus, this work aims to characterize levels of 18 selected PAHs in preschool environment, and to estimate exposure and assess the respective risks for 3-5-year-old children (in comparison with adults). Gaseous PAHs (mean of 44.5 ± 12.3 ng m(-3)) accounted for 87 % of the total concentration (ΣPAHs) with 3-ringed compounds being the most abundant (66 % of gaseous ΣPAHs). PAHs with 5 rings were the most abundant ones in the particulate phase (PM; mean of 6.89 ± 2.85 ng m(-3)) being predominantly found in PM1 (78 % particulate ΣPAHs). Overall child exposures to PAHs were not significantly different between older children (4-5 years old) and younger ones (3 years old). Total carcinogenic risks due to particulate-bound PAHs indoors were higher than outdoor ones. The estimated cancer risks of both preschool children and the staff were lower than the United States Environmental Protection Agency (USEPA) threshold of 10(-6) but slightly higher than WHO-based guideline.
... (7 ) Schwab et al. ( 1989bSchwab et al. ( , 1992 report on time ±activity data collected from 91 children in Kanawa Valley, WV, as part of a study of children's respiratory and sensory responses to air pollution. Schwab et al. (1991 ) explored the use of these diary data in linking exposure and dose by analyzing the self -reported exercise levels of the children. ...
... The challenge for exposure modelling is considering the daily variation, because longitudinal data for longer periods of time is limited. Despite the well-known deficiencies, many studies continue to consider cross-sectional data (24 h activity diaries) or two-days data, with fewer collecting data for a week or longer (Schwab et al., 1992;McCurdy and Graham, 2003). However, when assessing exposure we need to at least recognise the significant differences between the weekday routines and weekends. ...
This paper gives an example of the benefits of personal sampling (PS) and activity-based analysis (AA) for exposure assessment.
Air quality and exposure studies traditionally assume the same exposure for people living in the same area and neglect individual
mobility within the urban space and the the time spent indoors. This results in underestimation of true personal exposure.
Combining PS with AA overcomes this limitation, as it tracks individuals through their daily routines and regards exposure
at the contact point with pollutant. Two small longitudinal studies confirm significant differences in exposure profiles,
despite similar activity spaces of the subjects.
... (7 ) Schwab et al. ( 1989bSchwab et al. ( , 1992 report on time ±activity data collected from 91 children in Kanawa Valley, WV, as part of a study of children's respiratory and sensory responses to air pollution. Schwab et al. (1991 ) explored the use of these diary data in linking exposure and dose by analyzing the self -reported exercise levels of the children. ...
The National Human Activity Pattern Survey (NHAPS) was initiated to fill a need for updated activity information on a nationwide scale. The NHAPS, which begain in September, 1992, is a two-year probability-based national telephone interview survey of approximately 10,000 persons that is being conducted by the University of Maryland Survey Research Center assisted by the USEPA to ascertain the time, location, and other characteristics of those activities which are most relevant to estimating pollutant exposure. The survey design, location and activity codes, data examples, and appropriate analyses are described for the NHAPS data base. Time-diary data from this survey will provide standardized activity reports which, when available in early 1995, will be used to refine current human exposure models. Activity diary data have been effectively used in the following types of analyses: descriptive, relational, temporal, and exposure modeling. Examples of these analyses will be discussed and illustrated with data from previous activity surveys, including the recently available California survey. The applicability of these previous analyses to the new NHAPS data will be emphasized.
... Tobacco smoke is classified as a class "A" carcinogen along with asbestos, arsenic, benzene and radon gas [6,7]. Because many young pupils spend a large proportion of their time indoors, they may have significant exposure to environmental tobacco smoke in home [8]. This passive smoking has harmful effects on the respiratory health of such pupils [9,10]. ...
Background: Tobacco smoke is one of the most important sources of air pollution in home. It has been linked to many respiratory complications in pupils; however, there is great variation in intensity of these complications between individuals. The aim of this study is to determine effects of passive smoking on health and academic performance of male school-pupils in Khartoum. Methods: A random sample of 69 passive smokers (cases) was selected from three "Basic Education Schools" for boys in Khartoum. Inclusion criteria were a school pupil, 9-14 years old, not active smoker, exposed regularly to cigarette smoke in home since birth. A control group of 66 non-smokers with no history of regular environmental tobacco smoke exposure was selected from the same schools. The two groups were matched according to age, weight, height, socioeconomic status and area of residence. Information about smoking history, school performance and past medical history was collected from each pupil and his parents using a questionnaire. Results: Previous hospital admissions and surgical operations were not different between the two groups (P>0.05). History of upper and lower respiratory tract infections during the last year was found in 33 (47.8%) of cases and 23 (34.8%) of controls (P>0.05).Snoring during sleep was significantly higher among cases 11 (15.9%) than controls 3 (4.5%); (P=0.03, OR=3.98). Percentage of pupils with excellent academic performance in the last school examination was insignificantly lower in cases 8 (11.6%) than controls 13 (19.7%). Conclusion: Passive smoking causes significant snoring during sleep and insignificant increase in hospital admissions, surgical operations and respiratory infections among school-pupils in Khartoum.
... Second-hand smoke, especially in homes with children, poses a serious public health risk increasing the incidence of sudden infant death syndrome, respiratory illness, middle-ear disease and asthma [11,12]. Children aged between 3 and 11 years have the highest levels of SHSe, probably because they spend a majority of their time in close proximity to a caregiver who smokes [13][14][15]. Despite the strong national effort of introducing smoking bans in public spaces, children living with smokers have not experienced any reduction in their SHSe, as evidenced by serum cotinine levels [16]. ...
Concerns have been raised that the advent of electronic cigarettes (e-cigarettes) may be harmful to public health, and smokers have been advised by important agencies such as the US Food and Drug Administration not to use them. This paper argues that, while more research is needed on the cost-benefit equation of these products and the appropriate level and type of regulation for them, the harms have tended thus far to be overstated relative to the potential benefits. In particular: concern over repeated inhalation of propylene glycol is not borne out by toxicity studies with this compound; risk of accidental poisoning is no different from many household devices and chemicals available in supermarkets; concern that e-cigarettes may promote continued smoking by allowing smokers to cope with no-smoking environments is countered by the observation that most smokers use these products to try to quit and their use appears to enhance quitting motivation; concerns over low nicotine delivery are countered by evidence that the products provide significant craving reduction despite this in some cases; and e-cigarettes may help reduce toxin exposure to non-smokers.
... 6 7 In the Sudan, about 28% of school pupils live in homes where others smoke in their presence and 16.5% of all pupils have one or more parents who smoke. 4 Because many young children spend a large proportion of their time indoors, they may have significant exposure to second-hand smoke at home. 8 Cigarette smoke contains over 4000 compounds, many of which are extremely reactive affecting the physiology of the respiratory system and other systems in the body. 9 These include nicotine, tar, carbon monoxide and nitrogen oxides. ...
Background Exposure to second-hand tobacco smoke at home has been linked to many complications, including impaired lung ventilatory function; however, there is great variation in intensity of this complication between individuals of different countries. The aim of this study was to determine relationship between regular second-hand smoke exposure at home and the spirometric derived values forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), forced expiratory flow 50% and peak expiratory flow rate in healthy school boys in Khartoum.
Methods A total of 135 male school pupils were selected randomly from three governmental primary schools for boys in Khartoum. Inclusion criteria were healthy school pupil, 9–14 years old, not active smoker, either exposed regularly to cigarette smoke at home since birth or not exposed to cigarette smoke or any other type of smoke inside or outside the house. All spirometric measurements were performed using Clement Clarke All-flow Spirometer.
Results 69 school pupils were exposed regularly to second-hand smoke at home, whereas 66 pupils were not. Fathers were responsible for 67.5% of second-hand smoke at home; relatives for 30% and mothers for 2.5%. Mean FVC (±SD) was 2.21 ±0.57 l for the exposed pupils and 2.41 ±0.35 l for the non-exposed, showing reduction by about 8%. Mean FEV1 (mean ±SD) was 2.03 ±0.46 l for the exposed and 2.20 ±0.42 l for the non-exposed, indicating reduction by about 7%. The differences between the two groups were statistically significant (p<0.05).
Conclusion Regular second-hand smoke exposure at home causes significant reduction in FVC and FEV1 by about 7%–8% in school pupils in Khartoum.
... The scarcity of longitudinal time-activity data is in part due to the high cost of data collection. Only a limited number of studies have collected time-activity data on multiple days from individual participants in order to evaluate the intra-and inter-individual variations of time-location/activity patterns[2,[7][8][9][10][11][12][13]. Intraindividual variation refers to the variability of time-location/activity patterns of a person's activities, e.g., by time-of-the-day, day-of-the-week, season, and weather. ...
Longitudinal time-activity data are important for exposure modeling, since the extent to which short-term time-activity data represent long-term activity patterns is not well understood. This study was designed to evaluate longitudinal variations in human time-activity patterns.
We report on 24-hour recall diaries and questionnaires collected via the internet from 151 parents of young children (mostly under age 55), and from 55 older adults of ages 55 and older, for both a weekday and a weekend day every three months over an 18-month period. Parents also provided data for their children. The self-administrated diary and questionnaire distinguished ~30 frequently visited microenvironments and ~20 activities which we selected to represent opportunities for exposure to toxic environmental compounds. Due to the non-normal distribution of time-location/activity data, we employed generalized linear mixed-distribution mixed-effect models to examine intra- and inter-individual variations. Here we describe variation in the likelihood of and time spent engaging in an activity or being in a microenvironment by age group, day-type (weekday/weekend), season (warm/cool), sex, employment status, and over the follow-up period.
As expected, day-type and season influence time spent in many location and activity categories. Longitudinal changes were also observed, e.g., young children slept less with increasing follow-up, transit time increased, and time spent on working and shopping decreased during the study, possibly related to human physiological changes with age and changes in macro-economic factors such as gas prices and the economic recession.
This study provides valuable new information about time-activity assessed longitudinally in three major age groups and greatly expands our knowledge about intra- and inter-individual variations in time-location/activity patterns. Longitudinal variations beyond weekly and seasonal patterns should be taken into account in simulating long-term time-activity patterns in exposure modeling.
... Good indoor air quality (IAQ) is important for all of us; most people spend 90 % or more of their time indoors (Schwab et al., 1992). Most of this time consists of the hours spent at home or at work, but for example, school age children spend 20 % of their time in schools (Clench-Aas et al., 1999). ...
... In the United States, children spend most of their time (average, 20 hr) indoors (6). Therefore, in addition to considering the effects of outdoor air pollution (7), it is important to take into account the effects that exposure to indoor air pollutants may have on childhood asthma. ...
Exposure to indoor air pollutants such as tobacco smoke and dust mites may exacerbate childhood asthma. Environmental interventions to reduce exposures to these pollutants can help prevent exacerbations of the disease. Among the most important interventions is the elimination of environmental tobacco smoke from the environments of children with asthma. However, the effectiveness of reducing asthmatic children's exposure to environmental tobacco smoke on the severity of their symptoms has not yet been systematically evaluated. Dust mite reduction is another helpful environmental intervention. This can be achieved by enclosing the child's mattresses, blankets, and pillows in zippered polyurethane-coated casings. Primary prevention of asthma is not as well understood. It is anticipated that efforts to reduce smoking during pregnancy could reduce the incidence of asthma in children. European studies have suggested that reducing exposure to food and house dust mite antigens during lactation and for the first 12 months of life diminishes the development of allergic disorders in infants with high total IgE in the cord blood and a family history of atopy. Many children with asthma and their families are not receiving adequate counseling about environmental interventions from health care providers or other sources.
... An alternative approach is to use interview technique. Studies in the past have relied on daily activity diaries maintained by the subjects (WHO, 1984; Robinson, 1988; Dorre et al., 1990; Jenkins et al., 1990; Schwab et al., 1990 ). Other methods have been telephone interviews ( Jenkins et al., 1990 ) , open -ended activity -recall interviews (Zartarian et al., 1995, Dutt et al., 1996 ), standardized questionnaires (Brauer et al., 1996 ) and videotaping (Zartarian et al., 1995 ) . ...
The paper presents the application of the microenvironment approach for collection of time budget data to assess exposure of people to indoor air pollution. The aim of the study was to objectively test the hypothesis that exposure to pollutants from combustion of low-grade cooking fuels is a significant risk factor for acute respiratory infection (ARI) in infants (0-12 months). One of the specific objectives of this study was to estimate, in the winter season, the integrated daily exposure of infants and their mothers to respirable suspended particles (RSPs) and carbon monoxide (CO). The daily-integrated exposure was estimated by splitting the day into parts called microenvironments identified by the mobility patterns of the infants and mothers. These were so determined such that the spatial variation in the concentration of pollutants during these microenvironments is believed to be relatively insignificant under the given conditions, based on results of past studies and subjective judgement. The time spent in these microenvironments by the infants and mothers was determined by preparing time budgets. Very little correlation was found between the two methods of measurement (recall method and direct observation using a stopwatch) for the total time spent in cooking or time actually near the stove. It was observed that infants in houses using kerosene were near the stove for a duration that is 68% of the total cooking duration, while for infants in wood-using households this duration is only 44% (on the basis of the recall method, these numbers are 84% and 63% respectively). The infants spent more time in the indoor noncooking microenvironment irrespective of the fuel and slum type.
... Finally, scientists involved in estimating and simulating human exposures to environmental pollutants became interested in activity pattern research in the 1980s ( Robinson, 1988;Robinson and Thomas, 1991;Robinson et al., 1989;Adair and Spendler, 1989;Lichtenstein and Wyzga, 1989;Schwab, 1989;Schwab et al., 1990aSchwab et al., , 1991Schwab et al., , 1992Stock and Morandi, 1989 ). They emphasize proximity to potential sources of pollution, and Ð to a limited extent Ð the amount of time spent in e's with open windows and in activities involving high breathing rates (Johnson, 1984) . ...
EPA's National Exposure Research Laboratory (NERL) has combined data from 12 U.S. studies related to human activities into one comprehensive data system that can be accessed via the Internet. The data system is called the Consolidated Human Activity Database (CHAD) and is available at http:// www.epa.gov/nerl/. CHAD contains 22,968 person days of activity and is designed to assist exposure assessors and modelers in constructing population "cohorts" of people with specified characteristics that are suitable for subsequent analysis or modeling. This paper describes the studies comprising CHAD and the various intellectual foundations that underlay the gathering of human activity pattern data. Next, it provides a brief overview of the Internet version of CHAD, and discusses how the program was formulated. Emphasis is placed on how activity-specific energy expenditure estimates were developed. Finally, the paper recommends steps that should be taken to improve the collection of activity data that would improve energy expenditure estimates and related information needed for physiologically based exposure dose modeling efforts.
... (7 ) Schwab et al. ( 1989bSchwab et al. ( , 1992 report on time ±activity data collected from 91 children in Kanawa Valley, WV, as part of a study of children's respiratory and sensory responses to air pollution. Schwab et al. (1991 ) explored the use of these diary data in linking exposure and dose by analyzing the self -reported exercise levels of the children. ...
Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a 2-year probability-based telephone survey (
n=9386) of exposure-related human activities in the United States (U.S.) sponsored by the U.S. Environmental Protection Agency (EPA). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-h retrospective diaries and answers to a number of personal and exposure-related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day (i.e., each microenvironment). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board (CARB) sponsored a state-wide activity pattern study, and the mid-1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke (ETS) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.
... Nevertheless, nearly 900 000 children in the United States still had lead levels above the recommended limit (NHANES III). One source of this lead is certain indoor micro-environments where young children may spend as much as 88% of their time (Schwab et al., 1992). While some of this elevation is due to deteriorating leaded paint, some unknown portion may be due to leadwick candle-burning activity. ...
The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulates to the air and then deposited on indoor surfaces. To define the problem, 100 sets of candles (two or more identical candles) were purchased locally. The criterion for purchase was that the candles must appear to contain a metal-cored wick or be covered by a metallic pigment. Of the candles purchased, 8% contained lead wicks. The wicks were 39-74% lead (the remainder was fabric or paper) and the lead cores (approx. 100% lead) had linear densities of 13-27 mg/cm. Candles were burned to completion in a closed chamber to capture the air emissions, and the candle residue was extracted to assess the lead mass balance. It was found that individual candles emitted lead to the air at average rates that ranged from 100 to 1700 microg/h. Assuming realistic indoor conditions, these emission rates were modeled to project room air concentration, child exposure by inhalation, and indoor deposition. Results showed that burning single candles can easily raise the source room concentration above the ambient air lead concentration limit of 1.5 microg/m3 set by EPA. Burning multiple candles can elevate it above OSHA permissible exposure limits of 50 microg/m3. Although blood lead levels have dropped precipitously in the United States since lead was phased out of gasoline in 1986, nearly 900,000 children still had levels above 10 microg/dl during NHANES III. Considering that candle sales in the US are estimated at $1-2 billion per year, and that children may spend as much as 88% of their time indoors, it is reasonable to suspect that some blood lead elevation in children arises from indoor micro-environments where lead-wick candles are burned.
... 58 -61 In the United States, most children spend the majority of each day (average 20 hours) inside buildings. 62 Indoor air pollution has become a particular problem since the energy crisis of the 1970s, which led to the construction of more energyefficient buildings with less air circulation. ...
Environmental exposures may increase a child's risk of developing asthma and also may increase the risk of asthma exacerbations. This article reviews several environmental exposures and suggests whether they contribute to asthma prevalence, asthma exacerbations, or both. Outdoor air exposures and violence are not likely to cause the increase in asthma prevalence. Exposure to outdoor air pollutants primarily leads to increased exacerbations, sometimes manifested as asthma clusters. Clinicians should be alert for space-time clusters of asthma exacerbations in the community, because these clusters may suggest a modifiable point-source exposure. Indoor air exposures are more strongly linked to the increase in asthma prevalence. Exposure to dust mites and tobacco smoke are risk factors for the development of asthma and may also exacerbate existing asthma. Effective measures to prevent exposures to these pollutants are available. With proper management, the amount of environmental exposures can be decreased. Whether decreasing these exposures will result in decreases in asthma prevalence and exacerbations is not yet documented.
... ), whereas the following was determined: altering the C/NC cutoff to 591F (rather than 54 1F) and including June in the months July–September did increase the R a 2 to 0.19.Johnson, 1987; Schwab et al., 1990 Schwab et al., , 1992 Wiley et al., 1991; Klepeis et al., 1996 Klepeis et al., , 2001 Klepeis, 1996, 1997). On average, total indoor time approaches 21– 22 h/day. ...
This paper summarizes numerous statistical analyses focused on the US Environmental Protection Agency's Consolidated Human Activity Database (CHAD), used by many exposure modelers as the basis for data on what people do and where they spend their time. In doing so, modelers tend to divide the total population being analyzed into "cohorts", to reduce extraneous interindividual variability by focusing on people with common characteristics. Age and gender are typically used as the primary cohort-defining attributes, but more complex exposure models also use weather, day-of-the-week, and employment attributes for this purpose. We analyzed all of these attributes and others to determine if statistically significant differences exist among them to warrant their being used to define distinct cohort groups. We focused our attention mostly on the relationship between cohort attributes and the time spent outdoors, indoors, and in motor vehicles. Our results indicate that besides age and gender, other important attributes for defining cohorts are the physical activity level of individuals, weather factors such as daily maximum temperature in combination with months of the year, and combined weekday/weekend with employment status. Less important are precipitation and ethnic data. While statistically significant, the collective set of attributes does not explain a large amount of variance in outdoor, indoor, or in-vehicle locational decisions. Based on other research, parameters such as lifestyle and life stages that are absent from CHAD might have reduced the amount of unexplained variance. At this time, we recommend that exposure modelers use age and gender as "first-order" attributes to define cohorts followed by physical activity level, daily maximum temperature or other suitable weather parameters, and day type possibly beyond a simple weekday/weekend classification.
The report describes analyses of children's exercise information oriented toward putting a limit on activity-specific METS (metabolic equivalents of work) by age and gender.
Tobacco smoke (TS) exposure of children causes significant and completely preventable morbidity and mortality. The primary source of the TS to which children are exposed is smoking by parents or family members in the home. Clinicians who care for children can and should counsel families to make the child's environment completely smoke free and ultimately, to quit using tobacco altogether. In as little as three minutes, counseling to make environments smoke free and tobacco users to quit can be delivered. Basic techniques of behavior change counseling and cessation resources for families are discussed, including stages of change, the "Five A's," brief motivational messaging, and pharmacotherapies. The evidence supporting counseling of parents and patients to promote smoke free homes and tobacco use cessation is presented. Policies that promote smoke free homes are discussed briefly.
Due to their detrimental effects on human health, scientific interest in ultrafine particles (UFP), has been increasing but available information is far from comprehensive. Children, who represent one of the most susceptible subpopulation, spend the majority of time in schools and homes. Thus, the aim of this study is to (1) assess indoor levels of particle number concentrations (PNC) in ultrafine and fine (20-1000 nm) range at school and home environments and (2) compare indoor respective dose rates for 3- to 5-yr-old children. Indoor particle number concentrations in range of 20-1000 nm were consecutively measured during 56 d at two preschools (S1 and S2) and three homes (H1-H3) situated in Porto, Portugal. At both preschools different indoor microenvironments, such as classrooms and canteens, were evaluated. The results showed that total mean indoor PNC as determined for all indoor microenvironments were significantly higher at S1 than S2. At homes, indoor levels of PNC with means ranging between 1.09 × 10(4) and 1.24 × 10(4) particles/cm(3) were 10-70% lower than total indoor means of preschools (1.32 × 10(4) to 1.84 × 10(4) particles/cm(3)). Nevertheless, estimated dose rates of particles were 1.3- to 2.1-fold higher at homes than preschools, mainly due to longer period of time spent at home. Daily activity patterns of 3- to 5-yr-old children significantly influenced overall dose rates of particles. Therefore, future studies focusing on health effects of airborne pollutants always need to account for children's exposures in different microenvironments such as homes, schools, and transportation modes in order to obtain an accurate representation of children overall exposure.
Preadolescent children interact with a diverse array of physical, chemical, biological, and social factors in the environment that can pose a threat to their health. These can be naturally occurring risks such as bacterial contaminants in water, or pollutants, such as tobacco smoke, chemicals, and heavy metals. The potential for harmful effects from different environmental hazards depends on many factors including the intensity of the exposure, the toxicity of the substance, the duration of exposure, and route of contact. Most environmental threats pose a risk to the entire population, though children are usually more vulnerable.
A well-functioning voice is becoming increasingly important because voice-demanding professions are increasing. The largest proportion of voice disorders is caused by factors in the environment. Moisture damage is common and can initiate microbial growth and/or diffusion of chemicals from building materials. Indoor air problems due to moisture damage are associated with a number of health symptoms, for example, rhinitis, cough, and asthma symptoms. The purpose of this study was to investigate if children attending a day care center, preschool, or school with indoor air problems due to moisture damage were hoarse more often than the children in a control group.
Information was collected through electronic and paper questionnaires from the parents of 6- to 9-year-old children (n = 1857) attending 57 different day care centers, preschools, or schools with or without indoor air problems due to moisture damage.
The results showed a significant correlation between the degree of indoor air problem due to moisture damage and the frequency of hoarseness. Significant predictors for the child being hoarse every week or more often were dry cough, phlegm cough, and nasal congestion.
The results indicate that these symptoms and exposure to indoor air problems due to moisture damage should be included in voice anamnesis. Furthermore, efforts should be made to remediate indoor air problems due to moisture damage and to treat health symptoms.
Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Recent toxicological results highlight the importance of separating exposure to indoor- and outdoor-generated particles, due to their different physicochemical and toxicological properties. In this framework, a number of studies have attempted to estimate the relative contribution of particles of indoor and outdoor origins to indoor concentrations, using either statistical analysis of indoor and outdoor concentration time-series or mass balance equations. The aim of this work is to review and compare the methodologies developed in order to determine the ambient particle infiltration factor (F(INF)) (i.e., the fraction of ambient particles that enter indoors and remains suspended). The different approaches are grouped into four categories according to their methodological principles: (1) steady-state assumption using the steady-state form of the mass balance equation; (2) dynamic solution of the mass balance equation using complex statistical techniques; (3) experimental studies using conditions that simplify model calculations (e.g., decreasing the number of unknowns); and (4) infiltration surrogates using a particulate matter (PM) constituent with no indoor sources to act as surrogate of indoor PM of outdoor origin. Examination of the various methodologies and results reveals that estimating infiltration parameters is still challenging. The main difficulty lies in the separate calculation of penetration efficiency (P) and deposition rate (k). The values for these two parameters that are reported in the literature vary significantly. Deposition rate presents the widest range of values, both between studies and size fractions. Penetration efficiency seems to be more accurately calculated through the application of dynamic models. Overall, estimates of the infiltration factor generated using dynamic models and infiltration surrogates show good agreement. This is a strong argument in favor of the latter methodology, which is simple and easy to apply when chemical speciation data are available.
This paper presents methodology and results of a dynamic individual air pollution exposure model (DINEX) that calculates the hourly exposure for each adult in a panel study. Each of over 260 participants, through the use of a diary, provided information used in the model to calculate his/her personal, individualised exposure. The participants filled out the diary daily, hour by hour, over two, two month periods. The exposure assessment model coupled the diary information and results of an indoor/outdoor measurement program, with the results of dispersion modelling on an hourly basis for an industrial area in Norway. The estimated air pollution concentrations from the dispersion model, based on continuous meteorological measurements, were calibrated with air pollutant concentrations measured continuously.
Nickel and palladium nanoparticles were finely dispersed on ordered mesoporous silicon microchannels plate (MCP) by electroless plating. The structure and composition of the resulting Ni-Pd/Si MCP were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The electrocatalystic properties of Ni-Pd/Si MCP electrode for formaldehyde oxidation have been investigated by cyclic voltammetry. The results show that Ni-Pd/Si MCP has a higher catalytic activity and better steady-state behavior for formaldehyde oxidation. This may be attributed to the synergistic property of high dispersion of Nickel and Palladium nanoparticles and particular properties of mesoporous Si MCP. The present study shows a promising choice of Ni-Pd nanoparticles supported by mesoporous silicon as effective electrocatalyst for formaldehyde electrooxidation in alkaline medium. The results imply that the Ni-Pd/Si MCP nanocomposite has good potential application in formaldehyde fuel cells and sensors.
Over the past few decades rates of allergic diseases has been increasing, even more frequent in developed countries, nevertheless of their advances in science and techniques. It is so evident that some ones have called them as epidemic of the century XXI. At the beginning it was misunderstood but the scientists have showed that in part it is due to the pollutants and irritants, but also because of environmental allergens in many cases don't help to improving the patient. We make a review of the more frequent allergens irritants and pollutants that could worse or triggers allergic disease and, we give simple advices to prevent it.
Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal of improving the parameterization of human activity algorithms in EPA's exposure modeling efforts. Despite the longitudinal, multi-season nature of the study, participant non-compliance with the protocol over time did not play a major role in data collection. The diversity (D)-a ranked intraclass correlation coefficient (ICC)- and lag-one autocorrelation (A) statistics of study participants are presented for time spent in outdoor, motor vehicle, residential, and other-indoor locations. Day-type (workday versus non-workday, and weekday versus weekend), season, temperature, and gender differences in the time spent in selected locations and activities are described, and D & A statistics are presented. The overall D and ICC values ranged from approximately 0.08-0.26, while the mean population rank A values ranged from approximately 0.19-0.36. These statistics indicate that intra-individual variability exceeds explained inter-individual variability, and low day-to-day correlations among locations. Most exposure models do not address these behavioral characteristics, and thus underestimate population exposure distributions and subsequent health risks associated with environmental exposures.Journal of Exposure Science and Environmental Epidemiology advance online publication, 10 October 2012; doi:10.1038/jes.2012.94.
Poor indoor air quality has been linked to the exacerbation of asthma symptoms in children. Because people spend most of their time indoors, improving indoor air quality may provide some relief to asthma sufferers. A study was conducted to assess whether operating an air cleaning/ventilating unit (HEPAiRx®) in a child's bedroom can improve his/her respiratory health. Thirty children diagnosed with asthma were randomly split into two groups. For the first six weeks, group A had the air cleaning/ventilating unit (HEPAiRx®) running in the bedrooms of the participants and group B did not; for the second six weeks, both groups had the cleaners running in the bedrooms; and, for the final six weeks, group A turned the cleaners off and group B kept theirs running. Indoor air quality parameters, including temperature, relative humidity, particulate matter (PM 0.5–10 μm), carbon monoxide, carbon dioxide and total volatile organic compound (TVOC) concentrations, were monitored in each bedroom using an AirAdvice indoor air quality multi-meter. As a measure of pulmonary inflammation, exhaled breath condensate (EBC) was collected every sixth day and analyzed for nitrate and pH. Peak expiratory flow (PEF) was also measured. PM and TVOC concentrations decreased with operation of the HEPAiRx an average of 72% and 59%, respectively. The EBC nitrate concentrations decreased significantly and the EBC pH and PEF values increased significantly with operation of the unit (p < 0.001 when comparing on/off sample means). These results indicate that air cleaning in combination with ventilation can effectively reduce symptoms for asthma sufferers.
Lack of data on daily inhalation rate and activity of children has been an issue in health risk assessment of air pollutants. This study aimed to obtain the daily inhalation rate and intensity and frequency of physical activity in relation to the environment in Japanese preschool children. Children aged four-six years (n= 138) in the suburbs of Tokyo participated in this study, which involved three days' continuous monitoring of physical activity using a tri-axial accelerometer and parent's completion of a time/location diary during daily life. The estimated three-day mean daily inhalation rate (body temperature, pressure, saturated with water vapor) was 9.9 ± 1.6 m(3) /day (0.52 ± 0.09 m(3) /kg/day). The current daily inhalation rate value of 0.580 m(3) /kg/day proposed for use in health risk assessment in Japan is confirmed to be valid to calculate central value of inhaled dose of air pollutants in five- to six-year-old children. However, the 95th percentile daily inhalation rate of 0.83 m(3) /kg/day based on measurement for five-year-old children is recommended to be used to provide an upper bound estimate of exposure that ensure the protection of all five- to six-year-old children from the health risk of air pollutants. Children spent the majority of their time in sedentary and light level of physical activity (LPA) when indoors, while 85% of their time when outdoors was spent in LPA and moderate-to-vigorous physical activity. The results suggest the need to consider variability of minute respiratory ventilation rate according to the environment for more refined short-term health risk assessment.
This Technical Report was retired November 2017
Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.
This monograph is a compilation of child activity data obtained during investigations into lead transport and exposure pathways by the South Australian, Port Pirie Lead Investigation Group. These investigations included the use of activity time diaries, video recorded behaviour observation and questionnaires.
Mathematical models are available for the exposure assessment of compounds in consumer products. The computer program CONSEXPO is used for the calculations. Since the huge number of consumer products does not allow exposure assessment of every product separately, a limited number of main categories containing similar products are defined. A main category comprises product categories. The information on each main category is described in a fact sheet. This fact sheet supplies information on use of children's toys. The use of children's toys is described by classifying the ways in which children can be exposed. Representative examples are chosen for each way in which children can be exposed. Default models are chosen for these examples. The default parameter values are also filled in. Based on these representative example-defaults, it is possible to derive the default values for the exposure of any type of toy.
Om de blootstelling aan stoffen uit consumentenproducten en de opname daarvan door de mens te kunnen schatten en beoordelen zijn wiskundige modellen beschikbaar. Voor de berekening wordt gebruik gemaakt van het computerprogramma CONSEXPO. Het grote aantal consumentenproducten verhindert dat voor elk afzonderlijk product blootstellingsmodellen en parameterwaarden vastgesteld kunnen worden. Daarom zijn een beperkt aantal hoofdcategorien met gelijksoortige producten gedefinieerd. Voor elke hoofdcategorie wordt de informatie in een factsheet weergegeven. In de onderhavige factsheet wordt informatie gegeven over het gebruik van kinderspeelgoed. Het gebruik van kinderspeelgoed wordt beschreven uitgaande van de manieren waarop kinderen kunnen worden blootgesteld. Voor elke manier van blootstelling is een representatief voorbeeld gekozen. Voor deze voorbeelden zijn defaultmodellen gekozen en zijn de default-parameterwaarden ingevuld. Uitgaande van deze representatieve voorbeeld-defaults is het mogelijk om voor een willekeurig type speelgoed defaultwaarden voor de blootstelling af te leiden.
Children are becoming an increasingly important focus for exposure and risk assessments because they are more sensitive than adults to environmental contaminants. A necessary step in measuring the extent of children's exposure and in calculating risk assessments is to document how and where children spend their time. This 1990-1991 survey of 1000 households was designed for this purpose, targeting children between 5 and 12 years of age, in six states in varied geographic regions. The behavior of children was sampled on both weekdays and weekends over all four seasons of the year using a retrospective time diary to allocate time to activities during the previous 24 h. Information was obtained on the kinds and locations of activities, the nature of the microenvironments of the locations, and the time spent in the different environments. Measures of variability in addition to mean hours per day are reported. Results of this study closely match those of earlier research on California children's activities done by the California Air Resources Board. One important finding of the survey was that 5- to 12-year-old children in all geographic regions spend most of their time indoors at home, indicating that risk assessments should focus on indoor, onsite hazards.
We review the factors influencing children's exposure to environmental contaminants and the data available to characterize and assess that exposure. Children's activity pattern data requirements are demonstrated in the context of the algorithms used to estimate exposure by inhalation, dermal contact, and ingestion. Currently, data on children's exposures and activities are insufficient to adequately assess multimedia exposures to environmental contaminants. As a result, regulators use a series of default assumptions and exposure factors when conducting exposure assessments. Data to reduce uncertainty in the assumptions and exposure estimates are needed to ensure chemicals are regulated appropriately to protect children's health. To improve the database, advancement in the following general areas of research is required: identification of appropriate age/developmental benchmarks for categorizing children in exposure assessment; development and improvement of methods for monitoring children's exposures and activities; collection of activity pattern data for children (especially young children) required to assess exposure by all routes; collection of data on concentrations of environmental contaminants, biomarkers, and transfer coefficients that can be used as inputs to aggregate exposure models.
Isocyanates are the most prominent and well-studied cause of occupational asthma. Over the decades, airborne isocyanates have been regulated to extremely low levels in the workplace, some of the lowest for any organic compound. Yet the incidence of isocyanate-induced occupational asthma remains high and the role of dermal exposure in disease etiology is only slowly being recognized. Almost completely overlooked is the potential relationship between isocyanates in consumer products and increasing prevalence of asthma in the general population, especially children. The steady rise in asthma over the past decades points strongly to a potential role of environmental exposures in its development. Imbalances in the immune system favoring respiratory diseases have been linked to biological and chemical stressor exposures early in life. Evidence for the presence of isocyanates in many polyurethane-containing materials, especially polyurethane foams, is presented as a possible contributor to the increase in asthma. Polyurethane foam is ubiquitous in western societies and used in bedding, furniture, automobile seats, footwear, etc., and numerous medical materials. Theoretical, epidemiologic, experimental and clinical evidence of a role for isocyanates and polyurethanes in the genesis of non-occupational allergy and respiratory disease are reviewed. These data all point to the urgent need for additional research on the links between isocyanates, polyurethanes and the role of the skin in non-occupational asthma.
Four thousand elementary-school-age children from a rural area of western Pennsylvania participated in a cross-sectional survey that consisted of a standardized respiratory questionnaire completed by their parents and spirometric testing at school. Spirographic tracings were digitized to obtain the FVC, FEV0.75, FEF25-75, Vmax75, and Vmax90, which were standardized for height, age, and sex for the subsequent analyses. Independent associations of potential risk factors with the standardized pulmonary function measures were evaluated with multiple regression techniques. Asthma, persistent wheeze, and parental smoking habits, especially those of the mothers, were associated with lower flow rates. The effect of parental smoking was primarily due to smoking by the mother and was stronger in girls. In female children of currently smoking mothers, FEF25-75 was 96% of predicted, Vmax75 was 95% of predicted, and Vmax90 was 92% of predicted; each flow measure was 98% of predicted in male children of smoking mothers. Prolonged hospitalization at birth was independently associated with lower FEV0.75 and flow rates. Low socioeconomic status was associated with lower FVC and FEV0.75. Neither current gas stove use nor a history of severe chest illness before 2 yr of age were independently associated with lower levels of pulmonary function.
Standardized respiratory disease questionnaires (ATS-DLD-78-C) were completed by the parents of 4,071 children 5 to 14 yr of age, and risk factors for respiratory symptoms were evaluated by logistic analysis. Younger age, male sex, and lower socioeconomic status (SES) were independent risk factors for most respiratory symptoms and illnesses. All respiratory outcomes were significantly more prevalent in children with a physician's diagnosis of asthma. Asthma was more prevalent in male (4.5%) than in female (2.6%) children, and the greater prevalence of most respiratory symptoms in males did not persist in children with the same asthma status. Children whose questionnaires were completed by their fathers were reported to have significantly fewer respiratory symptoms than children with mother-completed questionnaires. We postulate that fathers underreport symptoms for their children. A positive parental history of allergy or respiratory illness was an independent predictor of respiratory symptoms and illnesses in the children. Chest illness before 2 yr of age and chest illness in the past year showed a significant positive linear trend with the number of parental smokers, and these effects of passive smoking were confirmed in the logistic analysis. The use of gas cooking stoves, inversely associated with SES, was not an independent risk factor for any respiratory symptoms or illnesses.
If medical geography is to contribute more fundamentally to the study of the environmental aspects of cancer etiology, it must be applied at the level of primary epidemiological analysis, namely, to the individual patient and control subject. Case and control studies of the environments specific to individuals (self-specific environments) can be made that explore differences indicative of associations between disease and environment. An example of a methodology used among 53 Chinese patients with nasopharyngeal carcinoma and 53 non-disease subjects in Selangor, Malaysia, is presented. Daily activity patterns are used to describe the use of time and space in terms of selected activities, selected settings, census districts, travel, and air pollution zones. The significance of relative risk ratios between cases and controls was tested with chi square. The methodology successfully establishes a time and space framework for self-specific environments for subsequent geographical analysis, and it has possible application to a wide range of health concerns besides cancer.
In recent years, considerable attention has focused on the concept of “human exposure” to environmental pollutants, but different investigators seem to have developed different definitions of this concept and used different approaches for estimating it. This paper reviews a number of “exposure” studies in a single environmental medium—air pollution—to see how others have defined this concept in the literature. Many previous investigators unfortunately calculate “exposures” by relying on data from fixed air monitoring stations, and they assume that people are located in the same place, usually their residential address, throughout a 24-h period. However, a second body of literature shows that fixed air monitoring stations do not necessarily reflect human exposures, because concentrations observed indoors—in homes, offices, factories, and motor vehicles—differ from those observed at fixed stations, and people usually spend considerable time in these locations. In an effort to standardize the nomenclature dealing with exposures, a definition is proposed in which the pollutant must come into contact with the physical boundary of the person. Then, exposure of person i to pollutant concentration c is viewed as two events occurring jointly: person i is present at a particular location, and concentration c is present at the same location. Mathematical definitions for “integrated exposure,” “average exposure,” and “standardized exposure” with various averaging periods also are introduced. Finally, two different yet compatible research approaches are suggested for determining human exposures to air pollution.
Alerts parents, teachers, and others to some of the leading indoor environmental hazards to young children which are caused by various types of indoor pollutants: cigarette smoke; heating/cooking equipment; asbestos; pesticides; art supplies; radon; and lead. Also suggests ways to reduce these health hazards. (BB)
A methodology for measuring the frequency distribution of carbon monoxide (CO) exposure in a representative sample of an urban population has been developed and applied in two urban areas: Washington, DC, and Denver, CO during the winter of 1982-1983. Exposure data using personal exposure monitors (PEMS) were collected, together with activity data from a stratified probability sample of residents living in each of the two urban areas. Well established survey sampling procedures were used for the selection of individuals. The resulting exposure data permit estimates of CO exposure for the eligible populations of the two areas, as well as statistical comparisons between population subgroups (e.g., commuters vs. noncommuters and residents with and without gas stoves). Results indicated that over 10% of the residents in Denver and 4% of the Washington, DC, residents were exposed to CO levels above 9 ppm for 8 h during the study period. The data also provide evidence for judging the accuracy of exposure estimates calculated from fixed site monitoring data.
Researchers have devoted considerable effort to identifying homogeneous travel-behavior groups, each of which also has distinctive sociodemographic characteristics. Interest in these efforts has been fueled by both theoretical and applied concerns. From a theoretical perspective, if such behaviorally and sociodemographically homogeneous groups cari be identified, we would have an improved understanding of the determinants of travel. From an applied perspective, because spatial choice models assume behavioral homogeneity within each sociodemographically defined subgroup, one would like to be able to identify groups that are homogeneous with respect to both behavior and sociodemographics. Most previous efforts to define such groups have classified individuals on the basis of one-day travel records. In this paper we review these efforts, note the problems inherent in using one-day travel records for identifying homogeneous travel-behavior groups, and use standard grouping procedures to classify individuals on the basis of behavior observed over a longer time period (five weeks). Using multi-day travel data means that the travel measures employed in classifying individuals are different from and more complex than those used with one-day data. We identify five travel-behavior groups, each of which has distinctive socio-demographic characteristics. Considerable intra-group variability remains, however, even though the groups are classified on the basis of longer-term behavior. The paper concludes with an examination of the implications of day-to-day variability in individual travel for classification procedures.
Four models for human exposure to air pollution are discussed and compared. The simple microenvironment monitoring model measures pollutant concentrations at fixed locations, regarded as proxies for similar locations or microenvironments. Since this model does not require pollutant measurements on the individual level, it is easy to implement. However, the model can only be used to estimate the average exposure in a population, and it does not provide any estimate of the variability and distribution of individual exposures. The replicated microenvironment monitoring model provides some estimates of the variability and distribution. However, because of the possible discrepancy between the microenvironment concentration distribution and the individual concentration distribution, some adjustment might be necessary. Integrated personal monitoring allows direct estimation of the average exposure as well as the variability and distribution of individual exposures. Coupled with the appropriate time budget data, a regression analysis can be applied to estimate the contribution from each microenvironment type. However, possible collinearity problems might result in low precision in those estimates. Moreover, it might be difficult to adjust for a possible Hawthorne effect. Continuous personal monitoring has the advantage of recording exposure in each microenvironment type separately, allowing direct estimation of the average exposure as well as the variability and distribution of exposures in each microenvironment type. Moreover, it can also be conducted in conjunction with a two-stage sampling scheme, using information from a large data base on activity patterns, thereby making more efficient use of the monitoring data. It is also easier to adjust for a possible Hawthorne effect in this design.
The unique features of and approaches to collecting time-diary data in the survey context are discussed. Sample diary report forms and activity coding schemes are presented and discussed, along with data from two national time-diary studies. These illustrate the range of useful data available from time diaries, as well as providing normative data regarding the amount of time that the American public spends in various activities. Location from diaries could be generalized to provide overall times spent in environments that vary in pollution levels.Various problems arise in matching these national time-use data with time estimate data from human exposure studies. The multiple respondent demands in these studies mean that daily activity patterns may be atypical and that respondents may also not report their activities as accurately or as completely as in a study founded solely on time. Some ways of reconciling these differences are proposed along with some suggestions for needed methodological research to increase the generalizability of pollution exposure estimates.
Investigations involving comparisons of populations, as well as intervention studies on groups, both under free-living and metabolic ward conditions, unequivocally demonstrate significant relationships between lipid components of the diet and serum cholesterol levels. However, low order or no correlations have been reported when these dietary variables and serum cholesterol are related for individuals. Several factors underlie this apparent paradox. This paper discusses at length the role of intra-individual variation in this apparent paradox, with particular emphasis on the errors caused by intra-individual variation in classification and estimation of correlation coefficients. Methods are presented for estimating the number of measurements required to achieve a suitable degree of accuracy for both classification and correlation analysis. Based on these theoretical considerations and practical examples illustrating their application, an assessment is made of commonly used dietary survey methods in terms of their appropriateness for measuring individual dietary intake. Suggestions are made for improving the design and methods of nutritional surveys, especially with regard to reducing errors introduced by intra-individual variation.
This report is based on a pilot project for a large epidemiologic study of inner-city asthma, in which exposures to air pollutants will be related to both incidence and prevalance of asthma. Nitrogen dioxide concentrations were measured in three rooms as well as outdoors in 44 inner-city apartments with gas cooking stoves. Fifty-two separate month-long series of 48-h time-integrated NO2 samples (Palmes tubes) were gathered from fall 1982 to spring 1984. The 48-h average NO2 concentrations taken within homes frequently exceeded the U.S. EPA outdoor annual mean NO2 standard of 100 μg/m3, and were observed to reach levels as high as 300 μg/m3 in some homes. Short-term peaks of NO2 were as high as 2000 μg/m3 at 2.3 m from the floor and 1700 μg/m3 at 1.7 m from the floor in kitchens. Activity records filled out by study subjects indicated an unusually large percentage of time spent indoors at home by inner-city residents, many of whom were asthma patients. On the basis of these activity patterns and the regular occurrence of high NO2 levels in inner-city apartments, individuals in this population are likely to have elevated personal exposure to this combustion by-product.
Personal NO2 exposure and indoor and outdoor concentrations were measured for nearly 350 individuals in the Portage, WI, area. Concentrations in homes with gas stoves averaged 18 μg/m3 higher in the summer (median indoor/outdoor ratio 2.4) and 36 μg/m3 (median indoor/outdoor ratio 3.2) higher in the winter than outdoor levels. Personal exposures were closely related to indoor averages for households with gas stoves (r = 0.85 summer, r = 0.87 winter) and with electric stoves (r = 0.68 summer, r = 0.61 winter); more than 65% of the average day was spent at home while about 15% was spent outdoors in summer and less than 5% in winter. The association between personal exposure and outdoor levels of NO2 was weakest during the winter for both gas (r = 0.20) and electric (r = 0.28) stove groups. The measures of exposure and time allocation indicate that there is a wide range of variability in personal exposures to NO2 that may not be adequately accounted for by simple stratifications based on cooking fuel type.
Recent developments in air pollution analysis have focused on methods for collecting data on contaminant levels in the locations actually frequented by people, especially personal monitoring. While there is still much to understand about human exposures, the next advancements will be in the area of dose assessment. This paper discusses the results of a study designed to provide data for linking exposure to dose. Specifically, we used time/activity diaries to collect information on the exertion levels associated with the reported activities. As part of a community health study, 91 children between the ages of 9 and 11 kept diaries over a two-week summer-time period (July 1989) and during a two-week school-time period (September 1989). The diary was also administered for two days to 42 teenagers between the ages of 15 and 17. This paper describes our concerns about interpreting self-reported exertion levels, particularly with respect to the disparity between participant and researcher perception and coding. We then present the distribution of exertion levels associated with children's activities, highlighting seasonal, day-of-week, and age-group differences.
Seven persons volunteered to perform 25 common activities thought to increase personal exposure to volatile organic chemicals (VOCs) during a 3-day monitoring period. Personal, indoor, and outdoor air samples were collected on Tenax cartridges three times per day (evening, overnight, and daytime) and analyzed by GC-MS for 17 target VOCs. Samples of exhaled breath were also collected before and after each monitoring period. About 20 activities resulted in increasing exposure to one or more of the target VOCs, often by factors of 10, sometimes by factors of 100, compared to exposures during the sleep period. These concentrations were far above the highest observed outdoor concentrations during the length of the study. Breath levels were often significantly correlated with previous personal exposures. Major exposures were associated with use of deodorizers (p-dichlorobenzene); washing clothes and dishes (chloroform); visiting a dry cleaners (1,1,1-trichloroethane, tetrachloroethylene); smoking (benzene, styrene); cleaning a car engine (xylenes, ethylbenzene, tetrachloroethylene); painting and using paint remover (n-decane, n-undecane); and working in a scientific laboratory (many VOCs). Continuously elevated indoor air levels of p-dichlorobenzene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, decane, and undecane were noted in several homes and attributed to unknown indoor sources. Measurements of exhaled breath suggested biological residence times in tissue of 12-18 hr and 20-30 hr for 1,1,1-trichloroethane and p-dichlorobenzene, respectively.
Results are presented from a second cross-sectional assessment of the association of air pollution with chronic respiratory health of children participating in the Six Cities Study of Air Pollution and Health. Air pollution measurements collected at quality-controlled monitoring stations included total suspended particulates (TSP), particulate matter less than 15 microns (PM15) and 2.5 microns (PM2.5) aerodynamic diameter, fine fraction aerosol sulfate (FSO4), SO2, O3, and No2. Reported rates of chronic cough, bronchitis, and chest illness during the 1980-1981 school year were positively associated with all measures of particulate pollution (TSP, PM15, PM2.5, and FSO4) and positively but less strongly associated with concentrations of two of the gases (SO2 and NO2). Frequency of earache also tended to be associated with particulate concentrations, but no associations were found with asthma, persistent wheeze, hay fever, or nonrespiratory illness. No associations were found between pollutant concentrations and any of the pulmonary function measures considered (FVC, FEV1, FEV0.75, and MMEF). Children with a history of wheeze or asthma had a much higher prevalence of respiratory symptoms, and there was some evidence that the association between air pollutant concentrations and symptom rates was stronger among children with these markers for hyperreactive airways. These data provide further evidence that rates of respiratory illnesses and symptoms are elevated among children living in cities with high particulate pollution. They also suggest that children with hyperreactive airways may be particularly susceptible to other respiratory symptoms when exposed to these pollutants.(ABSTRACT TRUNCATED AT 250 WORDS)
In studies in environmental epidemiology, exposure to harmful agents is often highly variable in time and space. It is not usually possible to measure the relevant, personal exposure of study subjects to these agents directly. Instead, exposure measurements are performed at fixed sites and/or for limited periods of time in many cases. Such measurements are imperfect in the sense that they only approximate the "true" personal exposure of study subjects. When measures of exposure are highly variable in time and space, single measurements approximate the true exposure only to a limited extent. The variability of measures of exposure can be investigated by repetition of the measurements in time and space. Analysis of variance techniques can be used to separate the within-subject or "error" variance from the between-subjects or true variance. Computation of the ratio between the error variance and the true variance is a useful technique to evaluate the potential bias in correlation and regression coefficients calculated with these measures of exposure. Using data from a number of different studies, the authors have estimated the variance ratio of lead exposure and nitrogen dioxide exposure variables. The results suggest that these ratios may be large. Empirical illustrations are given of bias in regression coefficients of childhood blood levels on different lead exposure variables. It is recommended that pilot studies be performed more routinely to estimate the magnitude of the variance ratios of exposure variables of interest in studies in environmental epidemiology.
As part of a longitudinal study of the respiratory health effects of indoor and outdoor air pollutants, pulmonary function, respiratory illness history, and symptom history were recorded at 2 successive annual examinations of 10,106 white children living in 6 cities in the United States. Parental education, illness history, and smoking habits also were recorded, along with the fuel used for cooking in the child's home. Maternal cigarette smoking was associated with increases of 20 to 35% in the rates of 8 respiratory illnesses and symptoms investigated, and paternal smoking was associated with smaller but still substantial increases. Illness and symptom rates were linearly related to the number of cigarettes smoked by the child's mother. Illness rates were higher for children of current smokers than for children of ex-smokers. The associations between maternal smoking status and childhood respiratory illnesses and symptoms were reduced but not eliminated by adjustment for parental illness history. Levels of forced expiratory volume in one second (FEV1) were significantly lower for children of current smokers than for children of nonsmokers at both examinations and highest for children of ex-smokers. Levels of forced vital capacity (FVC) were lower for children of nonsmokers than for children of current smokers at both examinations, but the difference was statistically significant only at the first examination. Both the increase in mean FVC and the decrease in mean FEV1 among children of current smokers were linearly related to daily cigarette consumption. None of the respiratory illnesses and symptoms studied was significantly associated with exposure to gas cooking in the child's home.(ABSTRACT TRUNCATED AT 250 WORDS)
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The serious business of growing up: a study of children's lives outside school
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Personal electronic sensor for mobility patterns
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An overview of the Los Angeles personal monitoring study
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The time/activity component of the Kanawha County Health Study
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The Kanawha County Health Study: A multiphase investigation of children's respiratory health and exposure to chemical industry emissions
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An activity pattern survey for asthmatics
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A comparative evaluation of self-reported and independently observed activity patterns in an air pollution health effects study
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