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Seasonal indoor radon concentration in the North West Frontier Province and federally administered tribal areas—Pakistan
Abstract
Indoor radon levels have been measured in several districts, namely Swabi, Mardan and Charsadda of the North West Frontier Province as well as in the Mohmand and Bajuar Agencies of the federally administered tribal areas, using CR-39-based radon dosimeters. In order to carry out this study, 200 houses were carefully selected and season wise indoor radon levels were measured throughout the year in four cycles. Seasonal correction factor was determined. Yearly arithmetic mean of 76±37 and was found in bedrooms and drawing rooms, respectively. Weighted arithmetic mean of the area was found to be . Yearly minimum values of 38±7 and were found in bedrooms and drawing rooms, respectively. A maximum value of was observed in the Charsadda district. Yearly weighted average minimum value of was found in the Mohmand agency and a maximum value of was found in the Charsadda district. Minimum indoor radon concentrations were found in the summer season whereas maximum levels were observed in the winter season. Seasonal correction factors for spring, winter, autumn and summer seasons were found to be 1.14±0.43, 0.89±0.47, 0.91±0.35 and 1.15±0.49, respectively. Weighted yearly average minimum indoor radon of 66±27 and were observed in the Swabi and Mardan districts and maximum level of was observed in the Bajuar agency. Using ICRP 65 conversion factor, minimum and maximum mean effective doses were found to be 0.46±0.20 and , respectively.
... Seasonal variation of indoor radon concentrations depends on several parameters such as geographical location, building materials, living habits of the inhabitant, ventilation system of the house, humidity of the soil underneath and surrounding the building and meteorological conditions, such as precipitation, the temperature differences between inside and outside air (Groves-Kirkby et al., 2009, Gillmore, 2005. A seasonal variation of indoor radon concentration has been investigated by many authors (Zunic et al., 2006;Bossew and Lettner, 2007;Rahman et al., 2007;Cortina et al., 2008;Neville and Hultquist, 2008;Kandari and Ramola, 2009;Stojanovska et al., 2011;Miles et al., 2012;Duggal et al., 2014;Wilson et al., 1991;Mose et al., 2006). Most studies showed a common pattern of the variation: indoor radon concentration in winter is greater than that in summer (Zunic et al., 2006;Bossew and Lettner, 2007;Rahman et al., 2007;Cortina et al., 2008;Neville and Hultquist, 2008;Kandari and Ramola, 2009;Stojanovska et al., 2011;Miles et al., 2012;Duggal et al., 2014). ...
... A seasonal variation of indoor radon concentration has been investigated by many authors (Zunic et al., 2006;Bossew and Lettner, 2007;Rahman et al., 2007;Cortina et al., 2008;Neville and Hultquist, 2008;Kandari and Ramola, 2009;Stojanovska et al., 2011;Miles et al., 2012;Duggal et al., 2014;Wilson et al., 1991;Mose et al., 2006). Most studies showed a common pattern of the variation: indoor radon concentration in winter is greater than that in summer (Zunic et al., 2006;Bossew and Lettner, 2007;Rahman et al., 2007;Cortina et al., 2008;Neville and Hultquist, 2008;Kandari and Ramola, 2009;Stojanovska et al., 2011;Miles et al., 2012;Duggal et al., 2014). This is attributed to keeping windows and doors closed in winter which allows radon to accumulate indoors whereas they are open most of the time during summer for ventilation purposes. ...
... Within the error bars of the average radon concentrations, we can conclude that COM A, COM B and research center have approximately the same values for winter and summer. In literature, it was commonly thought for many years that the indoor radon concentration has maximum values in winter and minimum values in summer (Zunic et al., 2006;Bossew and Lettner, 2007;Rahman et al., 2007;Cortina et al., 2008;Neville and Hultquist, 2008;Kandari and Ramola, 2009;Stojanovska et al., 2011;Miles et al., 2012;Duggal et al., 2014). This is due to the fact that during the cold months in winter the buildings are heated, which could create high difference in pressure between the soil and inside the buildings to allow more radon to escape inside. ...
... based on short-term passive measurements, using track detectors [11][12][13] , which prompted the need to use certain factors (temporal correction factors-TCF) in order to correct the fluctuations mentioned above [14][15][16][17] . Various studies, however, also report significant variations in the temporal correction factors, from one building to another, within the same measurement interval 18,19 , especially during the hot season [19][20][21][22] . Applying a regional or national average value for the temporal correction factor will lead to under/over estimation of true indoor radon exposure [23][24][25][26] , which could have long-term repercussions on human health 3,27 . ...
... Temporal correction factors for IRC using two different measuring methods. According to the data collected in the present study, illustrated in Fig. 2, as well as other similar studies [19][20][21] , seasonal correction factors obtained for the summer season for both passive and active methods show a high variability. The seasonal correction factors showed a log-normal distribution, confirmed by applying the Shapiro-Wilk test on logtransformed data. ...
The present study aims to identify novel means of increasing the accuracy of the estimated annual indoor radon concentration based on the application of temporal correction factors to short-term radon measurements. The necessity of accurate and more reliable temporal correction factors is in high demand, in the present age of speed. In this sense, radon measurements were continuously carried out, using a newly developed smart device accompanied by CR-39 detectors, for one full year, in 71 residential buildings located in 5 Romanian cities. The coefficient of variation for the temporal correction factors calculated for combinations between the start month and the duration of the measurement presented a low value (less than 10%) for measurements longer than 7 months, while a variability close to 20% can be reached by measurements of up to 4 months. Results obtained by generalized estimating equations indicate that average temporal correction factors are positively associated with CO 2 ratio, as well as the interaction between this parameter and the month in which the measurement took place. The impact of the indoor-outdoor temperature differences was statistically insignificant. The obtained results could represent a reference point in the elaboration of new strategies for calculating the temporal correction factors and, consequently, the reduction of the uncertainties related to the estimation of the annual indoor radon concentration.
... Measuring indoor radon and thoron concentrations and radon mapping was considered for years and several papers were published on the topic around the world [6][7][8][9][10][11][12][13][14][15][16][17], including in many Iranian cities [18][19][20][21][22][23][24][25][26][27] to increase public awareness of environmental radioactivity and to predict radon-prone areas, which would help authorities with regard to the development of an appropriate strategy to reduce public exposure to radon and thoron. This reduced exposure would increase the quality of life and improve public long-term health. ...
... Measuring indoor radon and thoron concentrations and radon mapping was considered for years and several papers were published on the topic around the world [6][7][8][9][10][11][12][13][14][15][16][17], including in many Iranian cities [18][19][20][21][22][23][24][25][26][27] to increase public awareness of environmental radioactivity and to predict radon-prone areas, which would help authorities with regard to the development of an appropriate strategy to reduce public exposure to radon and thoron. This reduced exposure would increase the quality of life and improve public longterm health. ...
A comprehensive study was carried out to measure indoor radon/thoron concentrations in 78 dwellings and soil-gas radon in the city of Mashhad, Iran during two seasons, using two common radon monitoring devices (NRPB and RADUET). In the winter, indoor radon concentrations measured between 75 ± 11 to 376 ± 24 Bq·m−3 (mean: 150 ± 19 Bq m−3), whereas indoor thoron concentrations ranged from below the Lower Limit of Detection (LLD) to 166 ± 10 Bq·m−3 (mean: 66 ± 8 Bq m−3), while radon and thoron concentrations in summer fell between 50 ± 11 and 305 ± 24 Bq·m−3 (mean 115 ± 18 Bq m−3) and from below the LLD to 122 ± 10 Bq m−3 (mean 48 ± 6 Bq·m−3), respectively. The annual average effective dose was estimated to be 3.7 ± 0.5 mSv yr−1. The soil-gas radon concentrations fell within the range from 1.07 ± 0.28 to 8.02 ± 0.65 kBq·m−3 (mean 3.07 ± 1.09 kBq·m−3). Finally, indoor radon maps were generated by ArcGIS software over a grid of 1 × 1 km2 using three different interpolation techniques. In grid cells where no data was observed, the arithmetic mean was used to predict a mean indoor radon concentration. Accordingly, inverse distance weighting (IDW) was proven to be more suitable for predicting mean indoor radon concentrations due to the lower mean absolute error (MAE) and root mean square error (RMSE). Meanwhile, the radiation health risk due to the residential exposure to radon and indoor gamma radiation exposure was also assessed.
... 2005), indoor radon/thoron concentration and flux were measured by Najeeb et al. 40 in Lahore and Kasur cities by using CN-85 SSNTD tubes. Similarly, Akram et al. 38 [44][45][46] In the same year, several districts of the Khyber Pakhtunkhwa and FATA were also scanned for indoor radon level through CR-39-based National Radiological Protection Board (NRPB) dosimeters by Rahman et al. 47 Further in the same year, seasonal variation in the indoor radon concentration levels in the same area has also been studied by Rahman et al. 48 and in six districts of the Punjab province including Gujranwala, Gujrat, Hafizabad, Sialkot, Narowal and Mandibahauddin districts by Faheem and Mati. 49 The seasonal correction factor (SCF) of indoor radon for these six districts was also calculated. ...
... While the semi-Pucka houses were made of stone, bricks and blocks with timber and mud roofs. Another two pre-earthquake (October 2005) studies were conducted in dwellings of the Muzaffarabad city and Rawalakot area of Kashmir by Iqbal et al. 44 In Khyber Pakhtunkhwa and FATA, radon concentration levels varied from 13.4 AE 6.3 to 323 AE 5 Bqm À3 in the bedrooms and from 21 AE 8 to 281 AE 5 Bqm À3 in the drawing rooms during summer season, reported by Rahman et al. 47 In the same area, seasonal variation was also reported by Rahman et al. 48 For this purpose, yearly survey of indoor radon concentration was conducted and the calculated SCF for the spring, winter, autumn and summer seasons was 1.14, 0.89, 0.91 and 1.15, respectively. According to their observation, minimum and maximum indoor radon concentration occurred in summer and winter season, respectively. ...
Radon is known to be a major source of public radiation exposure which could lead to increased incidence of lung cancer. Besides its health hazards, it also has potential geological, industrial and nuclear applications. In this context, radon measurements studies have been extensively conducted and reported all over the world. Keeping in view the importance of radon measurement levels, different research groups in Pakistan have also carried out and reported numerous studies since last several decades. However, these studies were scattered which were compiled and reported in 2008. Since then, considerable data have been reported for different cities/areas of Pakistan. The main objectives of the present article are to overview and compile these studies that will serve as baseline data for the radon levels in Pakistan.
... Several studies have been conducted at national and international levels to measure and set up remedial actions against indoor radon concentrations. In the past two decades, many individuals in Pakistan have tried to address the subject in specific regions of Pakistan [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. ...
... For France, Baysson et al. [9] have reported the SCFs of 0.93, 0.99, 1.075 and 0.99 for winter, spring, summer and autumn, respectively. In Pakistan, Faheem et al. [38] have reported SCFs of 1.14, 0.89, 0.91 and 1.15, which were reported for the spring, winter, autumn and summer seasons, respectively, and Rahman et al. [17] reported 1.15, 0.89, 0.91 and 1.15 for spring, winter, autumn and summer seasons, respectively. SCFs calculated for this study differ from the above-mentioned studies; this might be due to differences in the climatic, topographic and geological ...
Measurements of indoor radon concentrations in 200 dwellings of four districts of Azad Kashmir have been carried out using CR-39-based radon dosimeters. Indoor radon levels were calculated for four seasons (i.e. spring, summer, autumn and winter) in Muzaffarabad, Hattian, Neelum and Poonch districts. Maximum value of radon concentration (398 ± 2 Bq·m-3) has been found in Muzaffarabad district (in bedrooms) and minimum value (23 ± 9 Bq·m -3) is reported for Hattian district (in living rooms). Elevated values of radon levels have been found in winter, whilst lower values are observed in summer season. Seasonal correction factors calculated for spring, summer, autumn and winter seasons were found to be 1.02 ± 0.91, 0.86 ± 0.77, 0.98 ± 0.92 and 1.14 ± 1.04, respectively. Measured values for winter/spring, winter/summer and winter/autumn radon ratios were found as 1.11 ± 1.28, 1.33 ± 1.21 and 1.15 ± 1.17. Radon doses have been calculated and yearly mean effective dose has been found 2.52 ± 1.22 mSv, which is less than the lower limit of the recommended action level 3—10 mSv.
... Higher radon concentrations were recorded during winter than in the summer season. This phenomenon was observed in studies conducted in various regions [39][40][41][42]. The high variability in indoor radon concentrations in winter and summer may also occur as a result of changes in meteorological conditions, which, among other factors, have a direct impact on indoor radon concentrations [43,44]. ...
Radon in dwellings is recognized as the primary source of natural radiation exposure to members of the public. In the West Rand District and Soweto in the Gauteng Province (South Africa), indoor radon (222Rn) mapping was carried out to assess the exposure levels of radon in dwellings around gold and uranium mining tailings dams. This study was conducted predominately during warm and cold seasons, using the solid-state nuclear track detectors. In summer months, the indoor radon levels measured in all areas ranged from below the lower limit of detection to 71 Bq/m3, with a mean value of 29 Bq/m3, whereas in winter, the levels ranged between 11 and 124 Bq/m3, with a mean value of 46 Bq/m3. Higher indoor radon levels are found in colder months (winter season) than warmer months (summer season). However, no dwellings with indoor radon levels that exceed the WHO (2009) recommended reference level of 100 Bq/m3 were found, except for one that was constructed directly on soil mixed with tailings material. It is recommended that residents should keep their indoor radon levels low through continuous ventilation so as to minimize the buildup of radon and the likelihood of increased health hazards associated with radon exposure.
... Similarly, in Poland and Ireland the different factors were calculated for diverse regions [3]. Seasonal correction factors were calculated also in several Asian countries, such us in Korea [11]; Pakistan [12] and Turkey [13]. ...
In this study, 56 rooms were monitored throughout the year in four stages based on 3-month indoor radon measurements. The first seasonal correction factors for Slovakia were determined. Factors for spring, summer, autumn and winter seasons were found to be 1.15 ± 0.25, 1.48 ± 0.31, 0.86 ± 0.18 and 0.78 ± 0.17, respectively. Calculated seasonal correction factors were tested by independent measurements in houses. The preliminary results show a good correspondence between measured and calculated annual mean indoor radon activity concentration.
... where E WInh , C RnW , DCF, F, and R are the effective dose through inhalation, 222 Rn concentration in water (kBq/m 3 ), the dose conversion factor for 222 Rn exposure (9 nSv/(Bq h/m 3 ), the equilibrium factor between radon and its progenies (0.4), and the ratio of 222 Rn in the air to water (10 − 4 ), respectively (UNSCEAR, 1993(UNSCEAR, , 2000. The occupancy factor of an individual in various districts of Pakistan ranged from 0.41 to 0.51 with mean of 0.48 (Rahman et al., 2007). Using this factor the average occupancy time for an individual per day in indoor enviroment is 48%. ...
This study investigated the concentration of radon (222Rn) in hot springs water. For this purpose, 222Rn concentration was measured using the RAD7 (Durridge Company, USA) in the water of hot springs located in Tata Pani, Gilgit (n = 4), and Garam Chashma, Chitral (n = 6), northern Pakistan. Water samples from the springs (background, n = 3) were also collected and analyzed for 222Rn concentration 40-50 km away from the hot springs in Gilgit and Chitral, northern Pakistan, to be used as background/reference concentration. The determined 222Rn in hot springs water surpassed the threshold of maximum contamination level (MCL, 11.1 Bq/L) set by the United States Environmental Protection Agency (US-EPA) in 100% samples collected from Tata Pani, Gilgit, and Garam Chashma, Chitral sites. Soil 222Rn along with the hot springs exhibited a decreasing trend with increasing distance. 222Rn concentration in hot springs water was used to calculate the exposure doses of human health through ingestion and inhalation pathways. The total effective dose for human (EWT) of 222Rn contaminated water consumption was 626 μSv/a in the Tata Pani, Gilgit and 34.7 μSv/a in the Garam Chashma, Chitral. Results revealed that hot springs water in the Tata Pani, Gilgit had surpassed the threshold limit (100 μSv/a) set by the World Health Organization (WHO). This study concluded that hot springs water should be avoided for drinking and other domestic uses.
... The results of the seasonal and annual 222 Rn concentrations in the campus offices are summarized in Table. The [2,[7][8][9]. Due to the colder temperatures in the autumn and winter seasons, offices are more heated and less ventilated. This, in turn, results in lower indoor pressure and higher 222 Rn accumulation within a building. ...
In this study we measured radon (222Rn) concentrations in offices at the Meselik campus of Eskisehir Osmangazi University to estimate the effective dose of 222 Rn and its progeny for office occupants. The measurements were performed four times in 2011 over a period of 3 months using solid state nuclear track detectors (LR-115). A total of 381 LR-115 detectors were installed in 110 different offices, choosing three offices on each floor in the same building. 222Rn concentrations obtained in the first, second, third, and fourth measurement periods were 163 (73) Bq m-3, 105 (53) Bq m-3, 77 (43) Bq m-3, and 164 (70) Bq m-3 respectively. The 222Rn concentrations and seasonal 222 Rn variations in the offices were similar to those found in dwellings in Eskisehir. The total annual effective dose was estimated to be 3.398 mSv y-1.
... A long-term measurement period will give a much better indication of annual average radon concentration than measurements of shorter duration. Seasonal normalization factors (SNF) and monthly normalization factors (MNF) are numerical multipliers used to convert a short-term radon concentration measurements to estimates of annual average concentrations (S. Rahman et al., 2007;Kozak et al., 2011). K. Kozak et al. (2011) used a equation of GMY GMm (where GM Y is the geometric mean of annual radon concentrations and GM m is the geometric mean of monthly radon concentrations) to calculate monthly correction factor. ...
A series of experiments was conducted to measure indoor radon concentrations variations and observe any correlations with indoor and outdoor atmospheric parameters for over a period of one year. Indoor environmental parameters and radon concentrations were measured on an hourly basis in a two-story building both in a laboratory on the well-ventilated ground floor and in the basement below it which had negligible ventilation. The monthly average indoor radon concentration value of 29 ± 21 Bq m-3 in the laboratory was below the ICRP recommended limit of 200-300 Bq m-3. The monthly normalization factor for that location ranged from 0.5 to 2.0, while the seasonal normalization factor ranged from 0.78 to 2.0. In the unventilated basement, however, the average monthly indoor radon concentration was 1083 ± 6 Bq m-3 with little seasonal variation. The basement is only used for storage and thus the elevated radon concentration does not pose a serious health risk. The results indicated that indoor radon levels are higher in the autumn-winter season than in the spring-summer season. Analysis further showed that indoor radon concentrations negatively correlated with indoor humidity (correlation coefficient R = -0.14, p < 0.01), outdoor temperature (correlation coefficient R = -0.3, p < 0.01), outdoor dew point temperature (correlation coefficient R = -0.17, p < 0.01) and outdoor wind speeds (correlation coefficient R = -0.25, p < 0.05). Radon concentrations correlated positively with outdoor barometric pressure (correlation coefficient R = 0.35, p < 0.01), indoor-outdoor temperature difference (correlation coefficient R = 0.32, p < 0.05) and indoor-outdoor barometric pressure difference (correlation coefficient R = 0.67, p < 0.01). Indoor temperature, indoor barometric pressure and outdoor wind direction showed no clear correlations with indoor radon concentration.
... Its concentration levels depend strongly on geological, geophysical conditions and atmospheric factors. Being a noble gas, it has greater ability to migrate freely through soil, air and water [3][4][5]. ...
A study was conducted to measure indoor radon concentrations in dwellings of the Abbottabad city. In this regard, CR-39 based radon detectors were installed in drawing rooms and bedrooms of 40 selected houses and were exposed to indoor radon for 3 months. After exposure, the CR-39 detectors were etched for 8 hrs in 6M NaOH solution at 70 C and tracks were counted under an optical microscope. The observed tracks densities were related to radon
concentrations using a calibration factor of 2.7 tracks.cm .h /kBq.m . The mean annual estimated effective dose received by the residents of the studied area was found to be 1.48 ± 0.47 mSv y . Comparing the current indoor radon results with the published data of international agencies, it was found that the houses surveyed in the present study were within the safe limits
... The average worldwide annual effective dose equivalent from natural sources of radiation, in normal background areas, was estimated to be 2.4 mSv of which 1.275 mSv could be contributed by the indoor radon [5]. That is why a large number of groups throughout the world are engaged in the measurements of radon and its short-lived daughters on national levels [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In this regard, limited work has been done in the state of Azad Jammu and Kashmir (AJK). ...
In continuation to our earlier studies concerning generation of the baseline indoor radon data, an indoor radon measurement survey was carried out in the districts Bagh and Kahuta, state of the Azad Jammu and Kashmir. In this context, 150 houses were selected in the aforesaid districts and CN-85-based box-type radon detectors installed in bedroom and living room of each house. The detectors were exposed to indoor radon for 3 months. After etching CN-85 detectors in 6 M NaOH at 70°C for 3 h, the observed track densities were related to the indoor radon concentration using calibration factor of 0.0092 tracks cm−2·h−1 per Bq·m−3. The measured indoor radon concentration ranged from 56 to 124 Bq·m−3 and 61 to 106 Bq·m−3 in the studied areas of districts Bagh and Kahuta, respectively. The mean annual effective dose ranged from 1.42 ± 0.15 to 3.12 ± 0.10 mSv·y−1 with an average of 2.16 ± 0.13 mSv·y−1 in the district Bagh and 1.54 ± 0.14 to 2.68 ± 0.12 mSv·y−1 with an average of 2.17 ± 0.13 mSv·y−1 in the district Kahuta. These values are within the safe limits recommended by the World Heath Organization.
... These differences have been observed by many other authors (e.g. Rahman et al., 2007;Zunic et al., 2006;Cortina et al., 2008). The latter could be ascribed to the fact that during the colder months the buildings are heated, which creates a higher difference in pressure between the soil and the building. ...
... Indoor radon and its short-lived daughter products are known to contribute the largest fraction to the dose received by the general public from natural background radiation. This is why a large number of groups throughout the world are engaged in the measurements of radon and its short-lived daughters on national levels (Matiullah et al 2003, Rahman et al 2007b, 2007a, Munazza and Matiullah 2008, Rafique et al 2008, 2011a, 2011b, 2011c, 2011d, UNSCEAR 2000. In this regard, extensive radon surveys have been reported for many countries, including Pakistan, mainly in dwellings. ...
Indoor radon and its decay products are considered to be the second leading cause of lung cancer after cigarette smoking. This is why extensive radon surveys have been carried out in many countries of the world, including Pakistan. In this context, 25 spots were selected at workplaces in the vicinity of the uranium mining site in Dera Ghazi Khan District for indoor radon measurement. For this purpose, CR-39 based radon detectors were installed at head height and were exposed to indoor radon for 60 days. After retrieval, these detectors were etched in a 6 M solution of NaOH at the temperature of 80 °C for 16 h in order to make the alpha particle tracks visible. The observed track densities were related to the indoor radon concentration using a calibration factor of 2.7 tracks cm(-2) h(-1)/kBq m(-3). The measured indoor radon concentration ranged from ∼386 ±161 to 3028 ± 57 Bq m(-3) with an average value of 1508 ± 81 Bq m(-3) in the studied areas of Dera Ghazi Khan District. The mean annual effective dose ranged from 2.22 ± 0.93 to 17.44 ± 0.33 mSv yr(-1), with an average of 8.68 ± 0.47 mSv yr(-1). The effect of the seasonal correction factor (SCF) on the annual average radon concentration has also been considered. Results of the current study show that, for the majority of the workplaces studied, indoor radon levels exceed the action levels proposed by many world organisations.
Rn exists in nature in the form of a rare radioactive gas. In terms of environmental radiation, issues regarding ²²²Rn have persisted because of its radiological hazardousness. Ulju County is one of the regions of Ulsan metropolitan city, with a population of 227,699. Ulju County has the highest density of industrial complexes in Korea. In this study, ²²²Rn radioactivity concentration was measured and analyzed in 57 schools in Ulju County using 114 passive LR-115 type detectors to secure radiological safety and confirm basic information for reduction of resident exposure to ²²²Rn. The effective dose of ²²²Rn was assessed to find the actual risk of the concentration surveyed in schools to human beings. The dose depended on four factors: subjects, ²²²Rn concentration, dose coefficient, and time. The individuals subjected to dose estimation were classified into three types: students, teachers, and office workers. The subjects had different dwelling locations and times. The findings demonstrate that the radiological hazard to students and workers at schools in Ulju County owing to ²²²Rn is negligible in terms of ²²²Rn activity recommendation level.
In this study, indoor and outdoor radon ((222)Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013-2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and (222)Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor (222)Rn were estimated to be, respectively, 1.43 and 0.94 mSv y(-1). The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y(-1)). At the district level, the indoor annual effective dose equivalent in the İyidere district was 4.52 mSv y(-1), which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one.
Solid state nuclear track method and thermo luminescence dosimeter were used to measure indoor environmental radon concentrations and γ radiation levels in 100 buildings of different building ages, housing types, construction structures, decoration materials and floors in Chengdu. The results showed that the highest level of indoor environmental radon concentration in Chengdu is 177.1 Bq/m3, the lowest level is 8.4 Bq/m3, and the average level is (39.5 ± 22.9) Bq/m3, the data is lower than average value of the world; The highest level of indoor γ radiation in Chengdu is 164.7 nSv/h, the lowest level is 74.7 nSv/h, and the average level is (122.0±16.2) nSv/h, which is not concerned with indoor radon concentration. Statistical analyses showed that the differences of indoor environmental radon concentration among different building ages, types, floors, and decoration materials of buildings were significant. Radon and his daughter's annual effective dose to shine is 0.99 mSv, while the effective dose of γ radiation is 0.85 mSv every year.
Radon (222Rn) is a naturally occurring, invisible, odorless, colorless, tasteless and noble radioactive gas. The exposure of general population by ionizing radiation is generally due to the indoor radon since inception. The major part of indoor radon comes from building materials and the materials underlying the dwellings. In order to characterize the building materials as an indoor radon source, the knowledge of exhalation rate of radon from these materials is very important from radiological point of view. The unique characteristics of radon make it very attractive for earth science studies, as it can migrate over large distances within the earth and the atmosphere, be measured with accuracy, and be used as a tracer for many environmental processes of interest. 222Rn is a longest lived isotope in the three naturally occurring isotopes (i.e. 222Rn, 220Rn & 219Rn). It is both help and hazard. The probability of radon transport within the earth, in water and atmosphere makes it a useful tracer for a wide variety of geophysical, geochemical, hydrological and atmospheric purposes. It can move freely, so it is able to carry messages. Its applications range from exploration for uranium and hydrocarbon deposits to studying gas flow and mixing in the atmosphere to recognizing fluid transport within the earth, to predict seismic and volcanic events through premonitory changes in radon concentrations in the earth's lithosphere. Its measurements play a skilful role in monitoring human health safety, both in human dwellings and mines. It is a ubiquitous gas present in the natural environment and supposed to be the most important issue of health hazards caused by natural environmental radioactivity. Inhalation of radon and its progeny can cause lung cancer if it is present at enhanced levels beyond the permissible limit.
Environmental radiations exist everywhere and each natural substance contains trace amount of radioactive material. Radon alone contributes about 55% of total environmental radiations. Effects of these radiations on humans were firstly reported by Agricola for miners in the Erz Mountains of Eastern Europe in 1556 and in 1879 first association of lung cancer with miners were established. Nowadays indoor radon is believed to be second leading cause of lung cancer after smoking. Keeping in view the importance of subject indoor radon survey has been conducted in district Kotli of Azad Kashmir (Pakistan) using CN-85 based box type radon detectors. In this regard, 120 radon box type detectors were installed in a bedroom and living room of each house. The detectors were retrieved after exposing to the indoor radon for a period of 3 months and were etched in 6 N NaOH solution at 70°C for 3 hours. The observed track densities were then related to the indoor radon concentration. Arithmetic and geometric means were found to be 84±6 Bq. m-3, 73±6 Bq. m-3 and 80±6 Bq. m-3, 71±7 Bq. m-3 in the living rooms and bedrooms, respectively. For bed rooms indoor radon concentration varied from 38±9 to 107±5 Bq. m-3 whilst for living rooms 52±8 to 263±3 Bq. m-3. The overall mean value of the indoor radon concentration in the studied area was found to be 77±7 Bq. m-3. According to the recommendations made by the Health Protection Agency, UK (200 Bq. m-3), all the houses surveyed have the indoor radon concentration within the safe limits.
Results of indoor radon survey in the dwellings of district Bhimber are presented. Current study is continuation of our preceding studies aiming to setup baseline indoor radon data for the state of Azad Jammu & Kashmir, Pakistan. In this context, 60 representative houses were carefully selected and CN-85 based box type radon detectors were installed in bedrooms and living rooms of each house. The detectors were exposed to indoor radon for 90 days. After etching CN-85 detectors in 6M NaOH at 70 °C for 3 hours, the observed track densities were related to the indoor radon concentration using calibration factor of 0.0092 tracks cm 2/h per Bq/m 3. The measured indoor radon concentration ranged from 29 ± 11 to 58 ± 8 Bq/m 3, 40 ± 9 to 60 ± 7 Bq/m 3, and 29 ± 12 to 66 ± 7 Bq/m 3 in the regions of Bhimber, Samani, and Barnala, respectively. Excess relative risk factors were calculated using measured indoor radon concentrations, by using the risk model reported in the Biological Effects of Ionizing Radiation (BEIR VI, 1999) report. Excess relative risk was calculated for age groups of 35 and 55 years. Using local occupancy factor, average excess lung cancer risk for the population group of 35 and 55 years of age was found to be 0.42 ± 0.09 and 0.34 ± 0.08. The mean annual effective dose for Bhimber, Samani, and Barnala regions were found to be 1.05 ± 0.17 mSv, 1.09 ± 0.17 mSv, and 1.16 ± 0.17 mSv, respectively. These values are within in the safe limits recommended by the international organizations.
This paper presents the results of indoor radon concentration measurements in 120 dwellings of district Sudhnuti of Azad Kashmir. Measurements were taken with CR-39 passive alpha track detector. CR-39 based box type radon detectors were installed in a bedroom and living rooms of each house. The detectors were retrieved after exposing to indoor radon for period of 6 months and then etched in 6 M NaOH at 80°C for 16 h, the observed track densities were converted in to the indoor radon concentration. Indoor radon concentration varied from 20 ± 12 to 170 ± 4 Bq m−3 for the houses of the district Sudhnuti. Arithmetic mean (AM), geometric mean (GM) and geometric standard deviations (GSD) were found to be 82 ± 6, 77 ± 6 and 1.51, respectively. The minimum value of weighted average radon concentration was recorded in one of the house of Mang town, whereas the maximum value was found in the Pattan Sher Khan region. Doses due to indoor radon exposure vary from 0.50 ± 0.31 to 4.28 ± 0.11 mSv year−1 AM, GM and GSD. of mean effective doses were found to be 2.06 ± 0.13, 1.95 ± 0.18 and 1.51, respectively. According to the recommendations made by the Health Protection Agency, UK (200 Bq m−3) all the houses surveyed are within the safe limits.
CR-39 based radon detectors are widely used in measuring indoor radon. In this regard, different groups have developed their own systems. However, before using any system for indoor radon measurements, it has, first, to be calibrated with a known source of radon. In the current study, CR-39 based NRPB type radon detector has been calibrated and presented. In this regard, about 200 holders for CR-39 were obtained from the Radiation Protection Division of the Health Protection Agency (former NRPB), UK and several thousand more similar detector holders, hereafter called NRPB type holders, were fabricated locally in Pakistan. Uranium ore samples of known grade were placed into the plastic containers of volume 5.4 × 103 cm3 and CR-39 detectors were placed in the NRPB type holders and were then installed into the containers at a distance of 25 cm from the surface of the known grade ore samples. The containers were hermetically sealed and the detectors were allowed to expose to radon for 3 weeks. After 16 h etching in 25 % NaOH at 80 °C, the measured track densities were related to the radon concentration. The calibration factor of 2.563 tracks cm−2 h−1/kBq m−3 was obtained.
Contribution of radon and its decay products towards the total effective dose has been reported to be more than 50% and is a second leading cause of the lung cancer after cigarette smoking. It is an established fact that besides soil and rocks, naturally occurring radio nuclides are also associated with the petroleum extracted from the sedimentary deposits. Therefore, radon measurement around oil refineries is desirable. In this regard, an indoor radon measurement study was carried out in 40 dwellings which were situated in the vicinity of an oil refinery in the Rawalpindi district using CR-39-based radon detectors. For comparison, indoor radon levels were also measured in 40 dwellings situated at a greater distance (>2 km) from the refinery. The maximum measured indoor radon concentration was found to be 190 ± 6 Bq·m−3 whilst the minimum recorded concentration was 12 ± 7 Bq·m−3. The mean radon concentration in the dwellings surveyed was 57 ± 29 Bq·m−3. No significant difference was observed in the average indoor radon levels in the dwellings situated near the oil refinery premises when compared with those further away. From the measured radon concentrations, an annual effective dose was calculated to be 0.9 ± 0.1 mSv which is below the ICRP recommended value.
Radiation doses from indoor radon exposure, before and after the 2005 earthquake, have been assessed from measurements taken in the city of Muzaffarabad and Jhelum valley, Azad Kashmir, Pakistan. Indoor radon concentration was measured in dwellings in Muzaffarabad city and the Jhelum valley after the devastating 2005 earthquake using CR-39 based radon box type detectors which were exposed to indoor radon for 60 days. After processing, the observed track densities were related to the indoor radon concentrations using a calibration factor of 0.0092 tracks cm-2 · hr-1 = 1 Bq m-3 of 222 Rn and compared with already published data obtained before the earthquake. The post-earthquake weighted average indoor radon concentration ranged from 65 Bq m-3 to 398 Bq m-3 for the dwellings of state capital city of Azad Kashmir where pre-earthquake values were in the range of 89 Bq m-3 to 167 Bq m-3. In the Jhelum valley, post-earthquake indoor radon concentrations varied from 81 to 509 Bq m-3 and 64 to 456 Bq m-3 in the bedrooms and kitchens, respectively while pre-earthquake radon concentration for Jhelum valley ranges from 86 to 236 Bq m-3 and 62 to 208 Bq m-3 in the bedrooms and kitchens, respectively. The post earthquake indoor radon concentration levels and hence radiation doses have been found higher than those of pre-earthquake values.
Year-long measurements of indoor radon concentrations were taken in six districts of the Punjab province, Pakistan, using CR-39-based NRPB radon dosimeters. From the measured indoor radon concentrations, excess lung cancer risk was calculated using the risk model reported in the Biological Effects of Ionising Radiation (BEIR VI) report for the 35—54 and 55—64 year age groups. Using a local occupancy factor, average excess lung cancer risk for the 35—54 y age group residents was found to be 0.66, 0.52 and 0.37 for Gujranwala, Gujrat and Hafizabad districts, respectively. For the Sialkot, Mandibahauddin and Narowal districts it was 0.49, 0.57 and 0.59, respectively. Similarly, for the residents in the 55—64 year age group it was 0.5, 0.40, 0.47, 0.39, 0.46 and 0.46 for Gujranwala, Gujrat, Hafizabad, Sialkot, Mandibahauddin and Narowal districts, respectively. The overall average excess lung cancer risk for the area studied was 0.53.
A survey concerning measurement of the indoor radon levels has been carried out in 105 workplaces of the Rawalpindi region and Islamabad Capital Territory using CR-39 based radon detectors. The main objective of this study was to assess the health hazard due to the indoor radon. CR-39 based NRPB type detectors were installed in offices/rooms located on first floors, ground floors and basements and were exposed to indoor radon for six months. The measured indoor radon concentration in the buildings surveyed ranged from 12 ± 5 to 293 ± 19 Bq m−3 with an overall mean value of 64 ± 32 Bq m−3. The highest mean radon concentration (113 ± 48 Bq m−3) was observed in the offices located in basements of the Rawalpindi city. The overall average annual effective dose in the studied workplaces was estimated to be 0.61 ± 0.30 mSv. The mean annual effective doses in basements, ground floor and first floor were found to be 0.87 ± 0.34 mSv, 0.55 ± 0.28 mSv, and 0.47 ± 0.29 mSv, respectively. These values are less than the action level recommended by International Commission on Radiological Protection.
Seasonal indoor radon measurement studies have been carried out in four districts, namely, Jhelum, Chakwal, Rawalpindi and Attock of the Punjab Province. In this regard, CR-39 based detectors were installed in bedrooms, drawing rooms and kitchens of 40 randomly selected houses in each district. After exposing to radon in each season, CR-39 detectors were etched in 6M NaOH at 80 degrees C and counted under an optical microscope. Indoor radon activity concentrations in the houses surveyed ranged from 15 +/- 4 to 176 +/- 7 Bq m(-3) with an overall average value of 55 +/- 31 Bq m(-3). The observed annual average values are greater than the world average of 40 Bq m(-3). Maximum indoor radon concentration levels were observed in winter season whereas minimum levels were observed in summer season. None of the measured radon concentration value exceeded the action level of 200-400 Bq m(-3). The season/annual ratios for different type of dwellings varied from 0.87 +/- 0.93 to 1.14 +/- 1.10. The mean annual estimated effective dose received by the residents of the studied area was found to be 1.39 +/- 0.78 mSv. The annual estimated effective dose is less than the recommended action level (3-10 mSv).
The present study deals with measurement of indoor radon concentrations in dwellings of the district Poonch of the state of
Azad Jammu and Kashmir, Pakistan. In this context, CR-39-based box-type radon detectors were installed in drawing rooms and
bedrooms of 80 selected houses and were exposed to indoor radon for 3 months. After exposure, the CR-39 detectors were etched
for 9 h in 6 mol NaOH at 70°C and the observed track densities were related to radon concentrations. Measured indoor radon
concentrations in the studied area ranged from 27 ± 6 to 169 ± 4, 29 ± 6 to 196 ± 4 and 31 ± 5 to 142 ± 2 Bq m−3 in the drawing rooms and 74 ± 5 to 172 ± 3, 32 ± 6 to 191 ± 4 and 27 ± 5 to 155 ± 2 Bq m−3 in bedrooms of the Abbaspur, Hajira and Rawalakot regions of the district Poonch, respectively; whereas weighted average
radon concentration ranged from 93 ± 6 to 159 ± 4, 33 ± 5 to 118 ± 3 and 31 ± 6 to 155 ± 5 Bq m−3 in the dwellings of Abbaspur, Hajira and Rawalakot, respectively. Estimated doses due to the indoor radon ranged from 2.35
± 0.15 to 4.00 ± 0.10, 0.83 ± 0.08 to 2.98 ± 0.08 and 0.78 ± 0.15 to 3.91 ± 0.13 mSv y−1 for Abbaspur, Rawalakot and Hajira, respectively. Comparing the current indoor radon results with those of the Health Protection
Agency UK and US EPA (i.e. 200 and 148 Bq m−3) limits, majority of the houses surveyed in the present study are within the safe limits.
Studies concerning measurements of indoor radon levels were carried out in 60 schools in the Rawalpindi region of Pakistan. In each school, six CR-39 based NRPB type radon detectors were installed and exposed to the indoor radon in two cycles (each of six months' duration). After exposure, the detectors were removed, etched in 6 M NaOH for 16 h at 80 degrees C, and the tracks were counted under an optical microscope. The measured track densities were then related to radon concentrations, from which the radiation doses were calculated. The observed radon concentrations varied from 15 to 140 Bq m(-3), with an average activity concentration of 42.75 +/- 9.28 Bq m(-3). The mean annual radon effective dose equivalent was found to be 0.40 +/- 0.09 mSv using an occupancy factor of 8 h day(-1). Our results show that the indoor radon concentrations in the schools surveyed are within the permissible limits.
Radon is being extensively measured all over the world due to its hazardous health effects
as well as for different geological applications. In this regard, considerable studies have been
conducted by different research groups in Pakistan. However, these studies are scattered
and need to be combined/listed somewhere for future studies of radon in Pakistan. In this
article, all the studies concerning radon measurements have been reviewed. The main
emphasis is on different methods used in the measurement of radon. A minimum value of
5 Bq m−3
has been reported for a centrally air conditioned room and a maximum value of
782 ± 125 Bq m−3
has been observed in coal mines of Khushab, Punjab.
To conduct a radon awareness survey to examine the level of awareness and risk perception of indoor radon exposure among the general public, medical students, and physicians of the state of Azad Jammu and Kashmir, given that long-term exposure to indoor radon increases lifetime risk of lung cancer and may pose a substantial threat to public health.
Cross-sectional survey.
Households by telephone (500), interviews with menial laborers (200), questionnaires to shopkeepers and government employees (1,000), undergraduates (200), social science graduates (1,500), science graduates (1,500), medical students (325), and physicians (100).
Familiarity with radioactivity and the nature and health hazards of radiation and radon.
Significance of data trends was measured using the Kruskal-Wallis test.
About 30% people (excluding medical students and physicians) were aware of radon, and about 6% had knowledgeable awareness of radon. About 80% of the medical students and physicians had heard about radon and about 30.5% of them had knowledgeable awareness about radon and its hazards.
The study suggested a positive relationship of awareness of radon and its hazards with the educational level of people.
An investigation into the possible causes of childhood cancer has been carried out throughout England, Scotland and Wales over the period 1991-1998. All children known to be suffering from one or other type of the disease over periods of 4-5 years have been included, and control children matched for sex, age and area of residence have been selected at random from population registers. Information about both groups of children (with and without cancer) has been obtained from parental questionnaires, general practitioners' and hospital records, and from measurement of the extent of exposure to radon gas, terrestrial gamma radiation, and electric and magnetic fields. Samples of blood have also been obtained from the affected children and their parents and stored. Altogether 3838 children with cancer, including 1736 with leukaemia, and 7629 unaffected children have been studied. Detailed accounts are given of the nature of the information obtained in sections describing the general methodology of the study, the measurement of exposure to ionizing and non-ionizing radiation, the classification of solid tumours and leukaemias, and the biological material available for genetic analysis.
Indoor radon concentration levels have been measured in a number of cities in Jordan. CR-39 detectors were installed in randomly selected houses and were exposed to radon for about 4 months. The detectors were then etched in 6N NaOH at 70°C. It was observed that the indoor radon concentration levels varied from ∼ 7 to 123 Bq m−3.
The risk estimates for the general population extrapolated from the risk obtained from the miner studies leaded many national and international health organizations to estimate that residential exposure to radon and its decay products can be considered one of the main lung cancer risks after the tobacco smoking, which is responsible of a very large fraction of the total number of lung (and other) cancers. Due to this health relevance and to uncertainties in the extrapolation from studies on miners, many residential case-controls studies have been conducted in Europe, North America and China, are shortly reviewed in this paper. Most of these studies estimated an increased risk, proportional to the radon expo- sure, although a statistical significance of the estimated risk was reached only in few studies or restricted analyses, due to the low statistical power related to the relatively small study size and the presence of not negligible uncertainties in the evaluated radon exposure. The effects of these uncertainties were analyzed in some studies, and it was estimated to reduce the risk by 50% to 100%. Moreover, some restricted analyses showed that selecting subjects with a presumably better evaluation of radon exposure, for example with radon measurement covering all the exposure period of interest, the estimated risk increases by a factor of about two. The use of retrospective dosimetry compared with contemporary radon concentration measurements produce higher risks, too. In most of the studies a multiplicative interaction between tobacco smoking and radon is suggested, which implies that the lung cancer risk due to radon exposure is much higher for a smoker, compared with the risk for a never-smoker. More precise and definitive results are expected from pooled analysis. The just published pooled analyses of two Chinese studies and seven North American estimate a (slightly) significant excess odds ratio of 14% and 11% respectively. A more precise and comprehensive assessment is expected from the forthcoming results of the European pooling of 13 studies and the following pooling of all the studies. Other studies will be probably needed to answer some question on the risk for never-smokers and the interaction with passive smoking.
The results of continuous measurements of radon and other parameters in four buildings have been used to investigate the causes
of temporal variations in radon concentration, and to assess and quantify the accuracy of different radon measurement strategies
using passive detectors. The analysis showed that the four different houses had very different responses to outdoor temperature,
wind speed and direction. As expected, the results from all four houses show that longer measurements allow the annual average
radon level to be estimated more accurately than short measurements. In one house, which was shown to respond to the weather
in a manner typical of many Northern European houses, 90 day etched track or electret measurements could provide estimates
of the annual average concentration that were always within a factor of 1.5 of the true value, whereas estimates based on
charcoal detectors could exceed a factor of 2 from the true value. The effect of applying seasonal correction factors was
also investigated. In the typical house, applying these factors improved the accuracy of estimates of annual average radon
concentration, whichever measurement technique was used. In the three less typical houses, where radon levels were influenced
by wind speed and direction, the use of seasonal correction factors did not appear to be appropriate.
Seasonal variations of indoor radon concentrations have been studied in 70 single-family houses selected according to the type of sub-structure and the type of soil underneath the house. Five categories of sub-structure were included - slab-on-grade, crawl space, basement, and combinations of basement with slab-on-grade or crawl space. Half of the houses are located on clayey till and the other half on glaciofluvial gravel. In each house radon was measured in a living room and a bedroom, in the basement if present, and in the crawl space if present and accessible. The measurements were made with track detectors on a quarterly basis throughout a year. For living rooms and bedrooms the seasonal variations range from being highly significant for the slab-on-grade houses to being insignificant for the crawl space houses. For basements and crawl spaces the geometric mean radon concentrations do not show significant seasonal variations.
Indoor radon concentration levels were measured in a number of cities in Jordan using CR-39 based cup dosemeters and were found to vary from 27 to 88 Bq.m-3. The natural radioactivity in soil was also determined. The radon concentration levels were found to be dependent on the 226Ra content in the soil. The average radium equivalent activities in soil were found to be within the limit set by OECD countries but according to the present 1 mSv.y-1 dose limit, Jordanian soil is not acceptable as a construction material.
Indoor radon concentration of two consecutive half-year measuring periods in 3074 Finnish dwellings were analysed. The periods were the warmest and coldest half-year periods in Finland. The mean of winter/summer concentration ratio in all low-rise residential buildings was 1.28, and in houses with winter concentrations of <50, 50-100, 100-200 and >200 Bq.m-3, 0.97, 1.22, 1.34 and 1.55, respectively. The results are in agreement with the results predicted by the model, which takes into account the varying contribution of diffusive and convective radon entry as well as the contribution of stack effect and wind induced air infiltration. The model is a useful tool for estimating the average correction factor for the annual average radon concentration from the two months measurements used in Finland. Typical correction factors vary in the range of 1.0-0.7, depending on the outdoor temperature and on radon concentration level. Model comparison with winter/summer ratios measured in houses with slab on grade suggests an average diffusive radon entry rate of 7 Bq.m-3.h-1 and a convective entry rate of 50 Bq.m-3.h-1 at an average indoor/outdoor temperature difference of 17 K. The use of a simple averaging of winter/summer ratios for houses with varying radon levels, creates inaccuracy in the information on seasonal variation. Surprisingly, the behaviour of the winter/summer ratio in blocks of flats was very similar to that in low-rise residential buildings. The results support the interpretation that soil air leakage also contributes unexpectedly to the radon concentration in hats.
Accurate knowledge of exhalation rate plays an important role in characterization of the radon source strength in building materials and soil. It is a useful quantity to compare the relative importance of different materials and soil types. Majority of houses in Pakistan are mainly constructed from soil and sand. Therefore, studies concerning the determination of radon exhalation rate from these materials were carried out using CR-39 based NRPB radon dosimeters. In this context, samples were collected from different towns of the Bahawalpur Division, Punjab and major cities of NWFP. After treatment, samples were placed in plastic containers and dosimeters were installed in it at heights of 25cm above the surface of the samples. These containers were hermetically sealed and stored for three weeks to attain equilibrium between Rn-222 and Ra-226. After exposure to radon, CR-39 detectors were etched in 25% NaOH at 80 degrees C for 16h. From the measured radon concentration values, Rn-222 exhalation rates were determined. It ranged from 1.56 to 3.33 Bq m(-2) h(-1) for the soil collected from the Bahawalpur Division and 2.49-4.66 Bq m(-2) h(-1) for NWFP. The Rn-222 exhalation rates from the sand samples were found to range from 2.78 to 20.8 Bq m(-2) h(-1) for the Bahawalpur Division and from 0.99 to 4.2 Bq m(-2) h(-1) for NWFP. Ra-226 contents were also determined in the above samples which ranged from 28 to 36.5 Bq kg(-1) in the soil samples collected from the Bahawalpur Division and from 40.9 to 51.9 Bq kg(-1) in the samples collected from NWFP. In sand samples, Ra-226 contents ranged from 49.2 to 215 Bq kg(-1) and 22.6-27 Bq kg(-1) in the samples collected from the Bahawalpur Division and NWFP, respectively. 226Ra contents in these samples were also determined using HPGe detector. The results of both the techniques are in good agreement within experimental errors. (c)(c) 2006 Elsevier Ltd. All rights reserved.
A series of experiments were performed to determine the U-238 contents in U-bearing ore samples. In this context, ore samples were placed in plastic containers with CR-39-based NRPB radon dosimeters installed in them. The containers were then hermetically scaled and the dosimeters were exposed to radon for three weeks to equilibrate Rn-222 and Ra-226. After exposure, CR-39 detectors were etched in 25% NaOH at 80 degrees C for 16 h and counted under an optical microscope. The track densities thus obtained were related to radon concentrations using calibration factor of 2.7Tracks cm(-2) h(-1)(kBq m(-3)). From the measured radon concentration values, Ra-226 activities were calculated that ranged from 157 to 454 Bq kg(-1). Using these activity values, assuming secular equilibrium, U-238 contents were calculated which ranged from 13 to 37 ppm, in the ore samples under study. In order to verify the validity of the assumption of secular equilibrium, the above samples were analyzed with a high-resolution inductively coupled plasma atomic emission spectrometer (ICP-AES). The results obtained from this method showed higher 238U content that ranged from 356 to 2061 ppm which was a clear indication that there is disequilibrium between Ra-226 and U-238. Due to the unavailability of the 226Ra standard for ICP-AES, the equilibrium factor was therefore determined using HPGe-based gamma spectrometry technique. Here. specific activity of 226Ra was determined using gamma line at 609.3keV (46.1%) of Bi-214. Then specific activity of U-238 was determined using the gamma line at 143.76keV (10.5%) of U-235. Calibration factor, defined as the ratio of the specific activities of Ra-226 and U-238, was determined. The NRPB dosimeter data were then corrected for the equilibrium factor which resulted in U-238 contents that ranged from 229 to 1968 ppm. (c) 2005 Elsevier Ltd. All tights reserved.
Indoor radon concentrations are subject to seasonal variation and, in order to reflect annual averages, measurements made over periods other than twelve months need to be adjusted accordingly. A series of measurements made in the radon affected area of southwest England as part of an epidemiological study have been used to estimate seasonal correction factors. These are found to be substantial, and result in a change in the estimated annual average of up to 35% for measurements taken over a six month period, and 56% for measurements taken over a three month period. The results agree closely with previously published correction factors based on measurements made throughout the UK in an earlier time period. This confirms the stability of such correction factors over time. and the applicability of general UK correction factors to measurements of indoor radon in the radon affected area of southwest England.
Measurements concerning radon and its daughter products' concentration levels have been performed in 42 selective houses of the Tsukuba Science City (Japan) using CR-39 and LR-115 nuclear track detectors. These included both single story houses and flats in multi-storied buildings. Four CR-39 and four LR-115 detectors were put into a zippable polyethylene bag and a number of such bags were prepared. These detector loaded bags were then installed in two bedrooms of each of the houses/flats and were exposed for a period of three months during the winter season (i.e. from December to February). These radon exposed samples were then processed, analyzed and related to the Bq/m3. These studies indicated that the radon levels are very low in the houses surveyed and-do not pose any serious threat to the occupants.
An experiment was carried out to measure the radon and its airborne daughter product levels in the bed rooms of 40 houses. The houses chosen for this experiment were constructed from same building material and the bed rooms chosen were approximately of similar dimensions. The main objective of this experiment was to study the living standards (e.g. ventilation of the houses) of the residents from the measured values of radon and its daughter product concentration levels. Our results indicate that, except for a few cases, one can predict the living habits of the occupants from the measured values of radon and its daughter concentration levels.
Natural radioactivity in air, soil and water samples has been determined in Dera Ismail (D.I.) Khan city and its adjacent areas in Pakistan. CR-39 detectors were used for investigating radon concentration in the air of different kinds of rooms. HPGe detectors were employed for gamma ray activity measurements in the soil used normally to produce the construction materials. 235U concentration was determined from water by drying the water drops on CN-85 detectors and irradiating them with thermal neutrons.
Measurements of radon and its daughter products have been carried out in 13 houses in the city of Islamabad (Pakistan). Both CR-39 and CN-85 detectors were installed in bed rooms, kitchens and drawing rooms of the chosen houses and were exposed to radon and its daughters over a period of about four months. All the exposed detectors were processed employing the optimized etching conditions. Significant variation in radon concentration has been observed in the houses under investigation.
Radon concentrations were measured in some dwellings of Skardu city, Northern Pakistan. The measurements were based upon passive detection of radon using CN-85 etched track detectors in box-type dosimeters. After 60 days exposure of detectors to radon in the dwellings, the track densities in the etched detectors due to the emitted alpha particles from radon were measured and then converted to radon concentration values. The radon concentration was found to range from 76.04 to 152.38Bqm-3 with an average value of 111.34Bqm-3 in the dwellings under study.
Radon is radioactive; therefore, a radiation dose is associated with radon exposure. In the literature, values of radon dose conversion factor vary widely, and the meanings of radon dose can be quite different. It is important to understand what is really meant by a value of radon dose. A review of radon doses is given here. A summary table of different radon doses should be helpful to radon protection practitioners for better communication of radon risk to the public.
Data on radon concentration in the dwellings of Dera Ismail Khan area in Pakistan and gamma ray activities in the brick samples used in that area has already been reported. Based on that data we have estimated the internal dose to respiratory tract due to radon daughters and the external dose to lungs and whole body from gamma ray activity in the rooms made of clay bricks. For internal dose calculations the radon concentration has been converted to equilibrium equivalent concentration (EEC) by multiplying it with equilibrium factor of 0.4 as recommended in UNSCEAR. The EEC has been converted to equivalent dose rate using conversion factor of ICRP-50. The external dose from gamma ray activity has been determined by using a mesh adaptive method developed at our centre (CNS) for model rooms constructed from various materials.
Indoor radon level measurement survey has been performed in several districts of the North West Frontier Province (NWFP) and federally administered tribal areas (FATA), Pakistan. These include Swabi, Mardan and Charsadda Districts of NWFP and Mohmand and Bajuar Agencies of FATA. CR-39-based National Radiological Protection Board, UK-type radon dosimeters were used in this study. The dosimeters were installed in bedrooms and drawing rooms of a total of 200 carefully selected houses and were exposed to radon and its daughters for three months. In bedrooms, maximum radon concentration of was found in District Charsadda and minimum value of was found in the District Swabi. Like bedrooms, maximum radon concentration level in drawing rooms ( was also found in District Charsadda. Minimum level of indoor radon concentration of was found in a drawing room of District Mardan. According to the weighted average minimum indoor radon of was measured in Mardan and maximum of was measured in Charsadda District.
Indoor radon concentration levels in three main cities of Jordan have been measured using CR-39 polymeric nuclear track detectors. CR-39 detectors were placed in polyethylene bags and cups. These bag and cup dosimeters were installed in randomly selected houses. The average value of indoor radon concentration level in the city of Amman was found to be 41.3Bq m−3 with cup dosimeters and 42.6 Bq m−3 with bag dosimeters. For the district of Zarka, the average value of indoor radon concentration level measured with bag dosimeters was 33.9Bq m−3 , whereas with cup dosimeters the level was 30.7 Bq m−3. For Sault and its suburbs, the average value of indoor radon concentration level was found to be 51.2 Bq m−3 with bag dosimeters and 49.8 Bq n−3 with cup dosimeters.
An important achievement of nuclear track detectors is that they render it possible to measure a large number of radon concentrations. These are necessary for epidemiological studies aimed to estimate the lung cancer risk due to exposure to radon and its decay products in dwellings. Many case–control studies were conducted in the last 15 years in Europe, North America and China, in order to avoid the uncertainties associated with the risk extrapolation from epidemiological studies on miners exposed in underground mines. In this review paper, the main methodological issues of these studies are introduced: confounding factors, the impact of radon exposure uncertainties on the estimated risk, the retrospective assessment of radon exposure through the measurement of surface concentration on glass objects, the interaction between radon and smoking, statistical methods to analyze data and combine studies, etc. As regards the estimated risk of lung cancer, the main characteristics and results of each study are reported and discussed, together with the results of meta-analyses and, most importantly, of the three recently published analyses that pool 2 Chinese, 7 North American, and 13 European studies. Finally, some conclusions are given and a brief reference is made to ongoing studies.
Seasonal variations of indoor radon concentrations have been studied in 70 single-family houses selected according to the type of sub-structure and the type of soil underneath the house. Five categories of sub-structure were included - slab-on-grade, crawl space, basement, and combinations of basement with slab-on-grade or crawl space. Half of the houses are located on clayey till and the other half on glaciofluvial gravel. In each house radon was measured in a living room and a bedroom, in the basement if present, and in the crawl space if present and accessible. The measurements were made with track detectors on a quarterly basis throughout a year. For living rooms and bedrooms the seasonal variations range from being highly significant for the slab-on-grade houses to being insignificant for the crawl space houses. For basements and crawl spaces the geometric mean radon concentrations do not show significant seasonal variations.
Indoor radon concentration levels have been measured in 9 major cities of Jordan using CR(-3)9 detectors placed in punched polyethylene bags to measure both radon and thoron, and in cups to measure radon only. The average value of indoor radon and thoron concentration levels measured with bag dosimeters vary from 32 to 107 Bq m(-3) and the indoor radon concentration levels measured with cup dosimeters vary from 27 to 88 Bq m(-3). The indoor radon concentration levels in Irbid and Zaraka are comparable to the world average of 27 Bq m(-3). In Ajloun, Jerash, Salt, Tafilah and Amman, the indoor radon levels are greater than the world average by a factor of up to 2, and in Madaba and Karak these levels are greater than the world average by a factor of more than 3. The large variation in the measured radon levels may be attributed to the large variation in the 226Ra activity in the soil of the region.
Ionizing radiation dose levels due to home radon can rise to levels that would be illegal for workers in the nuclear industry. It is well known that radon levels within homes and from home to home, and also from month to month, vary considerably. To define an Isle of Man radon seasonal correction factor, readings were taken in eight homes over a 12 month period. An average island indoor exposure of 48 Bq m(-3) (range 4-518 Bq m(-3)) was determined from 285 homes selected from a cohort of 1300 families participating in the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) in the Isle of Man. This compares with a UK home average of 20 Bq m(-3) and a European Union average (excluding UK) of 68 Bq m(-3). Ten homes of those measured were found to have radon levels above the National Radiological Protection Board 200 Bq m(-3) action level. There are 29,377 homes on the Isle of Man, suggesting that there could be some 900 or more homes above the action level. No statistical difference was found between the NRPB and Isle of Man seasonal correction factors.
Indoor radon concentrations are subject to seasonal variation with a maximum in winter and a minimum in summer. Procedures to correct for seasonal variation are necessary in order to get an unbiased estimate of the annual average radon concentration from data based on short-period radon measurements. To obtain correction factors, we apply the model developed by Pinel et al to the French database of indoor radon measurements (measurements performed as part of the indoor radon case-control study and of the national radon measurement campaign). For 6-month measurements, the correction factors vary from 0.87 to 1.17 and agree with those previously published. These results might be applicable when assessing indoor radon concentrations with regard to recommended action levels.
Indoor radon concentration levels were measured in seven major cities of the Bahawalpur Division, Pakistan. These included Fort Abbas, Minchin Abad, Hasilpur, Bahawalpur, Liaqatpur, Rahimyar Khan and Sadiq Abad. In order to select houses for this survey, the inhabitants were approached through their school-registered children. Due to several constraints, only those 100 houses were chosen in each city that were relatively the best representatives of the built-up area. The selected houses were then divided into live categories according to the house locations and building characteristics. CR-39 detectors, placed in polyethylene bags. were installed at head height in bedrooms and sitting rooms of all the selected houses and were exposed to radon and its daughter products for 90 days. Four such measurements were performed over a year in order to average out the seasonal variation in radon levels. After exposure, all the detectors were etched and counted under an optical microscope. The track densities of four measurements were averaged out and related to radon concentration levels. The radon levels were found to be 20, 20, 26, 28, 34, 42, 47 Bq m(-3) in the bedrooms and 24, 26, 27, 26, 37, 40, 43 Bq m(-3) in sitting rooms of Hasilpur, Rahimyar Khan, Minchin Abad, Fort Abbas, Sadiq Abad, Bahawalpur and Liaqatpur respectively. The observed variation in the radon level may be attributed to the geological variation in the area. Based on the observed data, excess lung cancer risk was assessed using the risk factors recommended by the USEPA, UNSCEAR and the ICRP. According to the EPA model, the lifetime excess lung cancer risk due to the lifetime exposure is found to vary from 12-102 per million per year in the houses surveyed. This variation is from 16-114 and 26-62 per million per year if UNSCEAR and ICRP limits are applied respectively.
Bahawalpur is the largest division of the Punjab province in Pakistan. It is larger than many countries of the world. Gamma activity from the naturally occurring radionuclides namely 226Ra, 232Th, the primordial radionuclide 40K and the artificial radionuclide 137Cs was measured in the soil of the Bahawalpur division using gamma spectrometry technique. The mean activity of 226Ra, 232Th, 40K and 137Cs were found to be 32.9 +/- 0.9, 53.6 +/- 1.4, 647.4 +/- 14.1 and 1.5 +/- 0.2 Bq kg(-1), respectively. The mean radium equivalent activity Raeq, external hazard index, internal hazard index and terrestrial absorbed dose rate for the area under study are 158.5 +/- 4.1 Bq kg(-1), 0.4, 0.5 and 77.32 nGy h(-1), respectively. The annual effective dose equivalent to the public was found to be 0.5 mSv.
Two groups of buildings (29 in total) were examined to assess the time changeability in radon concentrations. All the buildings showed seasonal changes with the individual schemes of radon concentration changeability, which varied together with the changes in outside weather parameters, such as temperature and pressure. Measurements based on several days exposure give values ranging from 0.1 to 3.4 of the annual mean. Monthly measurements of radon concentration presented values from 0.3 to 1.8 of the annual mean. A major part of the examined houses showed negative correlation between the indoor radon concentrations and the outside temperatures, and positive correlation between the radon concentrations and the changes in the atmospheric pressure.
To identify the most applicable technology for the short-term assessment of domestic radon levels, comparative assessments of a number of integrating detector types, including track-etch, electret and activated charcoal were undertaken. Thirty-four unremediated dwellings in a high-radon area were monitored using track-etch detectors exposed for one-month and three-month periods. In parallel, one-week measurements were made in the same homes at one-month intervals, using co-located track-etch, charcoal and electret detectors exposed simultaneously, while three of the homes were also monitored by continuous-sampling detectors at hourly intervals over extended periods. Calibration of dose-integrating devices against each other and against continuous-monitoring systems confirmed good responsivity and linearity. Although track-etch, charcoal and electret devices are suitable in principle for one-week measurements, zero-exposure offset and natural radon variability cause many one-week results to be equivocal, necessitating repetition of the measurement. One-week exposures can be reliable indicators in low-radon areas or for new properties, but in high-radon areas, the use of three-month exposures is indicated. This analysis also established confidence limits for short-term measurements.
Significant progress has been made in reducing the risk from exposure to radon and its progeny all over the world as a result of efforts made by different organisations which are working together to educate public about the harmful effects of radon. During the past several surveys, it was found that uneducated people were totally ignorant of radon in Pakistan. Even a large number of science graduates knew very little about radon and its hazards. Therefore, a nationwide survey was conducted to measure general awareness and factual knowledge about radon and its health hazards. In this regard, a questionnaire was prepared and distributed among different classes of the society including students, government employees and general public throughout the country. A total of 7000 people with different educational backgrounds participated in this survey, which includes uneducated people (1000), science and humanities graduates (2000 each) and under graduate (2000). Statistical analysis, excluding uneducated people, revealed that 30.4% of the total respondents were aware of radon and 69.6% had even not heard of radon. Only approximately 8.4% of the total respondents were knowledgeably aware of radon.
The Meteorology of Pakistan: The Climate and Weathers of Pakistan
- K M Shamshad
Shamshad, K.M., 1988. The Meteorology of Pakistan: The Climate and Weathers of Pakistan. Royal Book Company, Sadder, Karachi, pp. 313, ISBN 9694070821.
Seasonal correction factors for indoor radon in the UK exposure in dwellings in France
- Pinel
Committee on health risks of exposure to radon-National Research Council), 1999. Health Effects of Exposure to Radon
- Beir-Vi