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Research Article Open Access
Tobin et al., J Pollut Eff Cont 2016, 4:1
http://dx.doi.org/10.4172/2375-4397.1000154
Research Article Open Access
Pollution Effects & Control
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ISSN: 2375-4397
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
Keywords: Air sampler; Respiratory symptoms; Spirometry; Wood dust
Introduction
Wood dust is produced when machines or tools are used to process
wood and is basically a by-product of the process, not produced for
any specic purpose [1,2]. Airborne, wood dust is the most prevalent
occupational exposure hazard in the wood industry [3,4]. Wood
dust inhalation has been associated with upper and lower respiratory
symptoms in humans including cough, wheezing, sputum production
and shortness of breath [5,6]. Syndromes that may arise include mucus
membrane irritation syndrome, extrinsic allergic alveolitis, organic
dust toxic syndrome, occupational asthma, non-asthmatic chronic
airow obstruction, simple chronic bronchitis (mucus hypersecretion),
cryptogenic brosing alveolitis, adenocarcinoma of the nasal and
paranasal sinuses, cancer of the larynx and pharynx [7,8]. Ill-health
from wood dust inhalation results in the inability of the worker to meet
the demands of his job, increased incidences of sickness absenteeism
and eventually early retirement [9]. Despite the potentially hazardous
nature of the work, there has been little attention given to their state
of health and safety in Nigeria by government health departments.
In the academia, few studies have focused on their morbidity pattern
with limited evidence of published data on dust exposure monitoring
in the face of an ever increasing number of sawmills operating within
the country in less than optimal conditions. e present study was
designed to investigate the prevalence of respiratory symptoms and lung
function among sawmill workers in Edo state, and measure particulate
dust concentration in sawmills as an index of exposure. It is envisaged
that the results of this study will add to the body of knowledge about
wood dust exposure in sawmills in Nigeria, and provide data useful
both for advocacy to government and for the planning and design of
interventions targeted towards dust control in the wood industry.
*Corresponding author: Ediagbonya TF, Department of Chemical Sciences, Ondo
State University of Science& Technology, Okitipupa, Nigeria, Tel: +2348069066577;
E-mail: tf.ediagbonya@gmail.com
Received June 03, 2015; Accepted February 03, 2016; Published February 09,
2016
Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational
Exposure to Wood Dust and Respiratory Health Status of Sawmill Workers in
South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Copyright: © 2016 Tobin EA, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Abstract
Ill-health from wood dust inhalation results in decreased work output and increased morbidity. Despite the
potentially hazardous nature of the work, there has been little attention given to the state of health and safety of the
workers in this industry in Nigeria. The study sought to investigate the prevalence of respiratory symptoms and lung
function abnormalities from occupational exposure to wood dust among sawmill workers, and assess wood dust
concentration in sawmills in Egor Local Government Area of Edo State. A cross-sectional analytical survey involving
227 workers from 17 sawmills recruited through a one stage cluster sampling technique and matched for age and
height with 227 workers in water bottling companies in the same locality was carried out. Structured questionnaires
and spirometry were used for data collection. Dust monitoring in the both study and comparison sites was carried
out with the aid of a gravimetric dust sampler. Data analysis was done using SPSS version 15 and PEPI version 10.
Ethical clearance was obtained from the University of Benin Teaching Hospital. Prevalence of respiratory symptoms
in the study group was: cough 46.7%, phlegm expectoration 50.2%, wheeze 5.3%, chest tightness 10.1%, chest
pain 5.7% and breathlessness 7.5%. Respiratory symptoms were of signicantly higher prevalence among the study
than the comparison group. Mean value for total and inhalable dust was signicantly higher (p = 0.00 and p =0.01
respectively) higher in the study than in the comparison sites. There was no signicant difference (p = 0.16) between
both sites for mean values of respirable dust.
Sawmill workers had a high prevalence of respiratory symptoms particularly cough and phlegm production, and
a higher exposure to total suspended and inhalable dust compared to suitably matched respondents. The results
have strong implications for improved dust control in the wood industry.
Occupational Exposure to Wood Dust and Respiratory Health Status of
Sawmill Workers in South-South Nigeria
Tobin EA1, Ediagbonya TF2*, Okojie OH3 and Asogun DA1
1Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo state, Nigeria
2Department of Chemical Sciences, Ondo State University of Science& Technology, Okitipupa, Nigeria
3Department of Community Health, University of Benin Teaching Hospital, Benin, Edo state, Nigeria
Materials and Methods
Study location
e study was carried out in Egor local government area of the
ancient town of Benin City, the capital of Edo state in the South –
south region of Nigeria. e city is noted for her age long tradition of
woodcra and furniture making, with the sale of timber contributing
signicantly to the economy of the state. A typical sawmill is a large
shed with a roof made of old corrugated zinc supported by wooden
poles. e oor is earth, and covered with several layers of sawdust.
e open shed houses one or more giant electrically driven band saw
and circular saw mounted on a fabricated metal table. Sawdust piles
surround the machines and may also be kept in a waste dump on the
premises, awaiting disposal, usually by burning. ere are about 10-20
workers in each mill, depending on the number of sawing machines,
and the volume of work at hand. e main activities in sawmill are
debarking and cutting of timber logs into planks. Both processes
generate wood dust, some of which is visible to the naked eye.
Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Page 2 of 6
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
Study population and design
e study which was carried out between August and December
2011 utilised a cross sectional analytical study design. e study group
comprised sawmill workers within the local government area who had
been in continuous employment in the industry for at least one year
preceding the study. e comparison group comprised junior sta of
various water packaging and bottling companies located in the same
local government area. ey belonged to similar socio-economic class
as the study group and included those who had never worked in sawmill
or other wood –related industry. ey were primarily involved in the
distilling, packaging, labelling and distribution of sachet and bottle
water. Sample size was calculated using the formula for comparative
studies with p1 and p2 taken as 4% and 0% respectively, being the
proportion of ventilatory dysfunction among sawmill workers in Benin
city and matched controls, in a study to assess the eect of wood dust
on the respiratory system, a minimum sample size of 227 in each group
was taken. Ethical approval for the study was obtained from the ethical
committee of the University of Benin Teaching Hospital, Benin. Written
informed consent was obtained from each participant.
Sampling method
A one stage cluster sampling technique was used to select participants
in the study group. A list of registered sawmills was obtained from the
Forestry department of the State Ministry of Agriculture. A preliminary
survey gave the average number of workers in sawmill as 15. e
minimum number of sawmills required to yield the sample size was
calculated as 14 (calculated by dividing the sample size by the average
number of workers in each mill). A table of random numbers was
used to select 17 out of 32 registered sawmills. In all selected sawmills,
eligible respondents were invited to participate in the study. Workers in
Water bottling factories within the LGA were matched for age (within a
10-year range), and height (within 10-cm range) with sawmill workers
on a group basis using frequency-matching technique [10] similar to
that used in an earlier study in the country [11], to ensure that they
were compatible and thus avoid the confounding eect of height and
age. All sawmill workers were male, so matching for sex was not done.
Data collection techniques
Data was collected by trained research assistants, Community
health extension workers in the local government health department.
An interviewer-administered structured medical and occupational
questionnaire adapted from the British Medical Research Council
(MRC) questionnaire on respiratory symptoms [12], which has been
validated and used for studies in the country [13,14] was applied to assess
the prevalence of symptoms among respondents. e questionnaire
was pre-tested in sawmill in another local government area within
the state. Cough and sputum were said to be present when the subject
had the symptoms either during the day or at night for 5 or more days
each week; breathlessness was dened as getting short of breath when
walking hurriedly with other people of same age on level ground or
when climbing up a low hill; chest tightness was dened as feeling tight
in the chest ,without a cold, on the rst days back at work on more
than 50% of occasions; wheeze was dened as whistling breathing;
Chest pain was assessed as a positive response to the questions “Do
you experience any pain or discomfort in your chest when hurrying on
level ground or climbing up a hill?” Cough with phlegm was implied
with a positive answer to the question “Have you had a period of
increased cough with phlegm in the last 3 months? To improve recall,
questions on presence of symptoms were limited to occurrence within
3 months prior to the conduct of the study. To control for smoking as
a confounder, respondents were further classied based on smoking
history. A non-smoker was one who had never smoked or who never
smoked as much as one cigarette a day for as long as 1 year; an ex-
smoker was one who smoked regularly as above, but has since stopped
for at least 1 month preceding the survey. A current smoker was one
still smoking as dened even as of the time of the survey.
e occupational section of the questionnaire sought information
on current job description, duration and a history of previous
employment. Physical examination of all participants involving
measurement of height and weight was undertaken. Standing height
was measured using a stadiometer with measuring range up to 78 inches
(207 cm) and graduations in 1/8 inch (1 mm) and standard procedure
[15]. Weight was determined using a digital scale with maximum
capacity of 150 kg in divisions of 100 grams. e respondent stood
in the centre of the scale, with hands by his side, with light clothing
and without shoes. Peak expiratory ow rate was determined on the
study and comparison groups in accordance with American oracic
Society (ATS) guidelines [16] using an electronic spirometer (Micro-
GP by Micromedical Ltd UK). Spirometric testing was carried out from
Tuesday to Friday and between the hours of 12.00 and 17.00, during
which time it was expected that sawmill participants had reasonably
been exposed to wood dust.
Area dust sampling was with the aid of a portable SKC Air check
XR5000 high volume gravimetric sampler model 210-5000, serial No.
20537 with technical assistance provided by the Department of Physics,
University of Benin, Nigeria. e sampling unit consisted of a gas pump
(which creates a ow of air that allows the contaminants in the air to be
captured), an in built ow rate meter (having a rating of 1000 ml/min
-5000 ml/min of air) and an I.O.M (Institute of Occupational medicine)
Multi dust sampler Batch no 221442/1 connected to the sampling pump
by a Teon tube. Sampling was done twice in all selected locations; the
rst time to determine total suspended particulates, and the second
for inhalable and respirable dust (particle selective sampling). Samples
of total suspended particles were collected on a pre-weighed 2.5cm
Whatman glass bre lter with pore size of 1.0 micron by pumping 2000
ml/min (2 L/min) volume of air through it for eight hours, between
8.00 and 16.00 hours without interruption. Aer sampling, the lter
was transported to the laboratory in a lter case. Dust concentration in
mg/m3 was calculated from the changes in weight of the lter (before
and aer sampling) divided by the volume of air sampled [17-20]. For
particle selective sampling, a Multi dust foam disc batch #225772 was
used in the I.O.M sampler cassette. In all 10 samples were collected:
one sample each from 5 sawmills and 5 from 5 purposively selected
locations within the factory premises. e 5 sites in the latter were
presumed to be areas with high human and/or dust generating activity
and included: the reception, factory oor, loading area, storage unit and
oce. In the sampled sawmills, the dust sampler was mounted on a
supporting pole at a height of 1.5meteres, and at a distance of 3 feet
away from the band saw in use.
Data analysis
Data was analysed using Statistical packages for social sciences
(SPSS) version 15.0 and ‘‘Computer Programs for Epidemiologists’’
(PEPI), version 10.0 [21]. Discrete data were presented as diagrams and
proportions (percentages) while continuous variables that were normal
in distribution (such as age and height) were expressed as means +
standard deviation. Statistical comparisons of the arithmetic means of
the study and comparison groups were carried out using the unpaired
student’s t-test (two –tailed). Statistical analysis of dierence between
proportions was done by the use of the χ2-test. Where the expected
Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Page 3 of 6
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
frequency in more than 20% of cells was less than 5, or any cell had an
expected cell count less than 1, Fishers’ exact test was used to test for
association between the variables.
Results
Socio-demographic characteristics
From Table 1, in all, 227 out of a total of 246 eligible all male workers
in 17 sawmills agreed to participate in the study, giving a response rate of
92.3%. A total of 227 respondents in the comparison group participated
as well. Subjects in both groups were generally comparable in terms of
age, height, the Body Mass Index (BMI) (p=0.63, p=0.36 and p=0.17
respectively). e majority in both study and comparison groups were
of Benin origin (37.9% and 55.1% respectively) and secondary level of
education was the highest level attained for the majority (57.5% and
73.6% respectively). ere was no signicant dierence in marital
status between the groups (p=0.64).
Self-reported prevalence of respiratory symptoms in studied groups
was as follows: cough 46.7%, phlegm production 50.2%, breathlessness
7.5%, wheeze 5.3%, chest pain 5.7%, chest tightness 10.1% and cough
with phlegm 8.8%. ere was also a signicantly higher prevalence of all
symptoms among current and ex-smokers than among non-smokers.
In relation to the comparison group, respondents in the study group
had a signicantly (p=0.00) higher prevalence of all symptoms.
Cough had the highest percentage of 41.2% in the study group of
Prevalence of respiratory symptoms among non-smokers in study and
comparison groups as shown in Table 2.
From Table 3, one hundred and y ve (68.3%) respondents in
the study group reported at least one respiratory symptom compared
with 23 (10.1%) in the comparison group. Non-smokers in the study
group had signicantly (p=0.00) higher proportion of all symptom.
e presence of at least one respiratory symptom among sawmill
subjects was signicantly associated with duration of work (p=0.04).
ere was no relationship between job category and history of previous
employment in a dusty occupation with occurrence of at least one
respiratory symptom. e FEV1/FVC ratio also called Tieneail-pinelli
[22] index, is a calculation ratio used in the diagnosis of obstructive
and restrictive lung disease [23,24], it represent the proportion of
Person’s vital capacity that are able to respire in the rst second of forced
respiration [25]. e mean values of all parameters Forced Expiratory
Volume in rst second (FEV1), Forced Vital Capacity (FVC), FEV1/FVC
and PEFR) were signicantly (p=0.00, 0.01, 0.00 and 0.00 respectively)
Symptom Study group
(N=227) n (%)
Comparison group
(N=227) n (%) χ2 test p value
Cough 106 (46.7) 18 (7.9) 85.92 0.00*
Phlegm 114(50.2) 11(4.8) 117.12 0.00*
Breathlessness 18 ( 7.5) 3 (1.3) 11.23 0.00*
Wheeze 14 ( 6.0) 3 (2.6) 6.08 0.00*
Chest pain 13 (5.7) 2 (0.9) 8.34 0.00*
Chest tightness 23 ( 10.1) 0 (0.0) 24.23 0.00*
Cough with phlegm 20 ( 8.8) 2 ( 0.9) 15.48 0.00*
*Signicant at p < 0.001
Table 1: Prevalence of respiratory symptoms in study and comparison groups.
Symptom Study group
n = 115
Comparison group
n = 156 p value
Cough 47 (41.2) 7 (4.5) 0.00*
Phlegm 43 (37.4) 0 (0.0) 0.00*
Breathlessness 3 (2.6) 0 (0.0) 0
Wheeze 1 (0.9) 0 (0.0) 0.00*
Chest tightness 3 (2.0) 0 (0.0) 0.00*
Cough with phlegm 4 (3.5) 0 (0.0) 0.00*
*signicant at p < 0.001
Table 2: Prevalence of respiratory symptoms among non-smokers in study and
comparison groups.
Variable
Sawmill group (n= 227) Comparison group (n = 227)
No symptom n (%) At least one
symptom n (%) Total No symptom n (%) At least one
symptom n (%) Total
History of previous dusty job
Yes 15 (41.7) 21 (58.3) 36 (100.0) 24 (70.6) 10 (29.4) 34(100)
No 57 (29.8) 134 (70.2) 191 (100.0) 180 (93.3) 13 (6.7) 193(100)
Total 72 (31.7) 155 (68.3) 227 (100.0) 204(89.9) 23 (10.1) 227(100)
χ2 = 1.96, df 1, p = 0.162 χ2 = 16.32, df 1 , p = 0.000
Duration of work (years)
< 4 37 (33.0) 75 (67.0) 112 (100.0) 96 (77.4) 28 (22.6) 124(100)
5 – 9 12 (21.1) 45 (78.9) 57 (100.0) 41 (89.1) 5 (10.9) 46(100)
10 – 14 9(29.0) 22 (71.0) 31 (100.0) 28 (90.3) 3 (9.7) 31(100)
> 15 14 (51.9) 13 (48.1) 27 (100.0) 20 (76.9) 6 (23.1) 26(100)
Total 72 (31.7) 155 (68.3) 227 (100.0) 185 (81.5) 42(18.5) 227(100)
χ2 = 8.24 df 3 , p = 0.041 Fisher’s exact test p = 0.137
Job category
Operator 22 (36.1) 39 (63.9) 61 (100.0)
Drawer/Table boy 21 (24.1) 66 (75.9) 87 (100.0)
Jack man 9 (25.7) 26 (74.3) 35 (100.0)
Maintenance 9 (50.0) 9 (50.0) 18 (100.0)
Manager 4 (40.0) 6 (60.0) 10 (100.0)
Loader/Packer 7 (43.8) 9 (56.2) 16 (100.0)
Total 72 (31.7) 155 (68.3) 227 (100.0)
χ2 = 7.59, df = 5, p = 0.18
Table 3: Factors associated with the presence of at least one respiratory symptom among study and comparison groups.
Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Page 4 of 6
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
higher in the comparison than among the study group as shown in
Table 4. Total suspended and inhalable dust levels were signicantly
(p=0.000 and 0.012 respectively) higher in study than comparison sites.
Respirable dust was higher in concentration, though not signicantly
(p = 0.156), in the study compared to comparison sites as shown in
Table 5.
Discussion
e higher prevalence of respiratory symptoms in the study group
gives the impression that occupational exposure to wood dust may
expose workers to a higher risk of developing pulmonary disorders.
is nding is in agreement with results from other comparative
studies [26-28]. Respondents in the study group reported a higher
prevalence of cough, and phlegm expectoration compared to chest
pain, chest tightness, wheeze or breathlessness. e implication is
that upper respiratory tract involvement was more likely compared
to lower respiratory tract involvement, the latter presenting with
wheeze, chest pain, breathlessness and tightness. is nding, which
has been similarly reported by other investigators [29-31] might be
as a result of the fact that wood dust, made up of cellulose and other
soluble chemicals including acetic acid and resins, is largely of large
diameter bres that irritate the cough receptors in the trachea and cause
mucostasis in the upper respiratory tract, leading to cough and phlegm
production. is is supported by area sampling of the study sites which
showed concentrations of total particulates clearly in excess of that
obtained from control sites with a clear absence of any form of dust
control mechanism in place. It may possibly also be due to the fact that
sawmill workers represent a ‘survival population’ that have experienced
less debilitating symptoms which otherwise would have sent them out
of the establishment.
About 68% of the study group and 10% of the comparison group
in the study reported at least one respiratory symptom, which was
lower than what was obtained in an earlier study conducted in the same
geopolitical region (87.6% in study group and 18.5% in the comparison)
[32,33] and comparable to what was obtained (62%) among wood
workers in Jos, Nigeria [34,35]. Respondents in the study group who
had put in less than 10 years in the trade had a signicantly higher
proportion of respiratory symptoms than those who had put in more
than 10 years. Correspondingly, the mean age of the former workers was
41.2 ± 7.7 years compared to the mean age of those who had put in less
than 10 years (29.0 ± 7.1 years). is may be explained by considering
that in the course of their work, as symptoms develop, those who are
worse aected tend to leave or change jobs leaving the ‘apparently
healthier’ ones behind. A comparison of non-smokers in both groups
showed prevalence of symptoms higher in the study compared to
comparison group, indicating that wood dust acts on the respiratory
tract independent of smoking. Similarly, when comparison was made
among non-smokers, spirometric readings and peak expiratory ow
readings were signicantly better in the comparison than the study
groups, though for both groups, the ratio of forced expiratory volume
in rst second and forced vital capacity (FEV1/FVC) was essentially
normal. is has been reported in previous studies outside the country
[36] and contrary to what was obtained in an earlier study carried out
in Tanzania [37].
e study sites had signicantly higher levels of total and inhalable
dust than control sites. Similar results have been documented in earlier
studies [38]. e higher concentration of dust might possibly explain
the high prevalence of upper airway irritation symptoms among
sawmill workers. Similar ndings have been documented in other
studies [39,40]. is can be explained by the fact that operations such
as debarking, sawing and cutting produce relatively coarse ( rather than
ne) dust that is largely in the thoracic fraction [41,42] with diameter
greater than 10 microns, and are thus outside the respirable range.
e processing of fresh (rather than dried) timber, as is the case with
sawmills in the study area, may also be responsible for production of
large diameter wood dust. Respirable wood dust (<5.0 to 0.5 microns
in size and designated PM2.5), made up a small proportion (31%) of
inhalable dust concentration in the sawmills, and not signicantly
dierent from what was obtained in comparison sites. us only a
small portion of wood dust generated actually penetrated the deeper
lung tissue to provoke pathological changes. However, because of the
irritant and allergic properties of wood dust, this small proportion is
responsible for the higher prevalence of lower respiratory symptoms
among study than control subjects. Previous employment in a dusty job
was not associated with presence of at least one respiratory symptom in
the study as against the control group, implying a continued destruction
of lung tissue by wood dust exposure in spite of previous assault from
other inhaled agent encountered in previous work.
e Time weighted average (TWA) for total inhalable wood dust
in the study sites (1.39 mg/m3), fell below the 15 mg/m3 permissible
exposure limit (PEL) set by the Occupational safety and health
administration (OSHA) for total inhalable wood dust for an 8-hour
work- shi. While this nding is obviously not due to the existence
of dust extraction systems in the sawmills, the most likely explanation
may be the fact that the study sites, being open sheds, have a good
supply of natural ventilation, which serve to readily disperse the dust.
Moreover, the gravimetric sampler used measures airborne dust, and
since wood particles generated during debarking and planning are to an
extent of large diameter, they settle quickly to the ground and may not
be measured. Also, the limits specied by these regulatory bodies apply
mainly to personal exposure sampling, whereas, the value obtained in
this study was based on area sampling, which may give lower values,
and therefore be an underestimation of worker exposure to wood dust.
e value obtained for total inhalable dust in this study was higher than
Parameter Sawmill workers Mean
± SD N = 115
Control group Mean
± SD N = 156 p value
FEV1 (L) 3.07 ± 0.51 3.30 ± 0.53 0
FVC (L) 3.60 ± 0.70 3.79 ± 0.69 0.01
FEV1/FVC 77.64 ± 4.32 79.48 ± 6.26 0
PEFR (L/min) 404.11 ± 88.80 457.40 ± 84.45 0
Table 4: Comparison of lung function among non-smokers in study and comparison
groups.
Sampling location
Type of particulate Study site
(n = 5)
Comparison site
(n = 5) t test (p value)
Total suspended
particulates (mg/m3)
mean ± SD 1.39 ± 0.28 0.52 ± 0.07 6.77
(Range) (0.94 – 1.67) (0.83 -1.67) 0
Inhalable suspended
particulates (mg/m3)
mean ± SD 1.07 ± 0.34 0.44 ± 0.09 4.07
(Range) (0.60 – 1.66) (0.31 – 0.53) -0.01
Respirable suspended
particulates (mg/m3)
mean ± SD 0.33 ± 0.12 0.23 ± 0.08 1.57
(Range) (0.17 – 0.57) (0.10 – 0.31) -0.16
Table 5: Assessment of mean particulate concentration in study and comparison
sites.
Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Page 5 of 6
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
what was obtained in sawmill in Canada [43] (0.2 mg/m3), probably
because the Canadian mills may have dust extraction systems in use.
e value obtained was comparable to that obtained from the sawmill
section of a wood furniture factory in ailand [44,45], a developing
country like Nigeria.
e TWA for respirable dust obtained in this study (0.33mg/m3)
was also well below the PEL set by OSHA (5 mg/m3), and the 1 mg/m3
recommended exposure limit set by National Institute of Occupational
Safety and Health (NIOSH). e value was lower than what was
obtained in a study in Calabar (31.75 mg/m3) [46] possibly because of
the dierence in air sampling equipment’s used in both studies. e
value for respirable dust in this study was similar to what was obtained
in sawmill in Sweden (0.3 mg/m3) [47]. A limitation of the study is that
assessment of respiratory symptoms was made based on self-report,
and was not validated using medical records.
Conclusion
Sawmills in a developing country like Nigeria face the challenge
of providing work environments where hazards such as wood dust are
poorly controlled. Sawmill workers in Nigeria are like their counterparts
elsewhere therefore at an increased risk of developing respiratory
symptoms from occupational exposure to wood dust. Symptoms from
this study were predominantly from aectation of the upper airway, and
showed a signicantly higher prevalence in smokers than non-smokers.
Area sampling of sawmills showed higher concentrations of particulate
dust than in control sites. It is needful for dust control mechanisms
to be put in place in sawmills, and sawmill workers educated on the
need to use protective devices while at work. Standards for permissible
dust exposure levels should be set for sawmills in Nigeria to guide
monitoring.
Acknowledgement
The authors would like to express their gratitude to the research assistants who
participated in data collection, to the Sawmill managers who granted permission
to recruit their workers as well as to the study participants. The authors are also
grateful to the management of the Water bottling factories for permitting their staff
to participate in the study.
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Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016) Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-4397.1000154
Page 6 of 6
Volume 4 • Issue 1 • 1000154
J Pollut Eff Cont
ISSN:2375-4397 JPE, an open access journal
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Citation: Tobin EA, Ediagbonya TF, Okojie OH, Asogun DA (2016)
Occupational Exposure to Wood Dust and Respiratory Health Status of Sawmill
Workers in South-South Nigeria. J Pollut Eff Cont 4: 154. doi:10.4172/2375-
4397.1000154
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