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EUROPEAN JOURNAL OF INTERDISCIPLINARY RESEARCH
VOL. 1, NO. 1, September 2020, pages 1-20
DOI: http://dx.doi.org/10.5281/zenodo.3996147
Evaluation of perceived effects from exposure to
occupational noise pollution on hearing loss
among cement factory workers
By Charity O. Chukumah* , Gabriel C. C. Ndinwa*
& Solomon A. Akpafun**
* Department of Industrial Safety & Environmental Management, School of Environmental Studies, Delta State
School of Marine Technology, Burutu, Nigeria
** Department of Urban & Regional Planning, School of Environmental Studies, Delta State School of Marine
Technology, Burutu, Nigeria
I. Introduction
Noise has been documented as one of the bye-products of human’s quest for
industrialization as well as scientifically proven as an off-shoot of production
ABSTRACT
This study was designed to evaluate the perceived effects from exposure to
occupational noise pollution on hearing loss among cement factory workers in Edo
State, Nigeria. A descriptive cross-sectional survey design was adopted for the study,
and 183 factory workers who were mainly males working at different departments in
the factory, were sampled. A well designed and structured questionnaire was used to
obtain personal and scientific information from the participants. The questionnaire was
sectionalized into four major aspects. Background noise levels and that of the work
environment was measured using calibrated Wensen WS 1361 type 2 digital sound
level meter. Student t-test was used to analyse the test of association between hours at
work and hearing loss; whereas the prediction of hearing loss was determined using
multinomial logistic regression model. All statistical significances were considered at
p<0.05. The results revealed that a larger proportion of the participants demonstrated
higher level of awareness on the effects of noise on health. Greater number of
participants revealed higher percentage on the general use of hearing protection
device; and further revealed, was that most of the participants presented high
frequency of hearing loss. Participants from the storage and transportation (ST)
department had the lowest prevalence of hearing loss at PTA512 and PTA346 when
compared with participants from other departments. No significant relationship was
established to exist between the hours at work and hearing status for both ears at
PTA512 and PTA346. The multiple regression analysis revealed no significant relationship
between the selected predictors and hearing loss for both ears at PTA512. However, age
was revealed as a significant predictor of hearing status at PTA346 for both ears because
a positive relationship was established between age and hearing status.
KEYWORDS
Hearing loss
Noise pollution
Edo state
Factory workers
Nigeria
ARTICLE HISTORY
Accepted 20/08/2020
Published 01/09/2020
🅔 CHUKUMAH, NDINWA & AKPAFUN
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processes called energy residual (John et al., 2016). Noise pollution has been
explained in different ways by different scholars to mean any unwanted and
unpleasant sound; quantitatively produced by a combination of different sounds and
wave lengths as well as intensities without a clear and definite composition to the
ears (Ahmadzadeh, 1996). It is an unpleasant and bothering sound wave, produced by
changes in the pressure of ambient air. To differentiate between noise and sound
depends on the interpretation of the interest of the person receiving the sound, the
environmental conditions and immediate impact generated by the sound at that
particular time. At present, noise pollution has been proven to be among the physical
environmental factors impacting on human’s health worldwide (Ibrahim, 2016). It is a
recognized threat to human well-being. In extreme range, noise can lead to human
hearing impairment and has been classified by the United States Environmental
Protection Agency as a serious health hazard (USEPA, 1974). In addition to its
capability in causing hearing loss, noise has been scientifically documented to impact
on human psychological and physiological systems including a multitude of bodily
stress responses (Atmaca et al., 2005).
The impact of noise on the general well-being of factory workers has been a
global issue currently undergoing serious debate among scientists for the past
decades (Pandya and Dharmadhikari, 2002; Concha-Barrientos et al., 2004; Nelson et
al., 2005; Singh et al., 2013; Noweir et al., 2014; Lie et al., 2016). Several noise
exposure legislations have been enacted to limit its impact on human’s health in
other parts of the world. The Occupational Noise Exposure Regulation of the United
States enforces industrial employers to limit noise exposure of their workers to 90
dBA for a period of 8-hours per workday (Eleftheriou, 2002). A similar maximum noise
exposure dose of less than 75 dBA for a period of 7½-hours per workday was
enacted in Turkey to reduce the degree of high intensity of noise exposure to workers
(Republic of Turkey Ministry of Environment, 1986). Continuous exposure of extensive
noise level higher than 85 dBA can impact on hearing loss; and continuous hearing
loss varies from person to person depending on the frequency, duration and level of
exposure (Melamed et al., 2001). The impacts of noise on the general well-being of
workers are physiological and psychological in nature. These impacts include any
long-term or temporary lowering of the psychological, physical and social functioning
of human organs (Cheung, 2004).
The perceived impact of noise in the day-to-day work operations of factory
workers are of major importance to their general well-being and noise-induced
hearing loss have been reported in other countries as the most common effects
among the physiological impact (Singh et al., 2013). Globally, hearing impairment has
been reported to be the most prevalent irreversible occupational hazard associated
to the day-to-day operations of factory workers. In 1995, 120 million people were
reported by World Health Assembly to suffer from varying degree of disabling
hearing difficulties. It has also been reported that men and women are equally at risk
of hearing impairment from exposure to high intensity of noise. In developing
countries like Nigeria, hearing impairment arising from occupational noise exposure
EUROPEAN JOURNAL OF INTERDISCIPLINARY RESEARCH 🅔
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is a major public health concern that has been neglected for decades. With regard to
the quest for rapid industrialization, a reasonable percentage of factory workers have
been reported to suffer from occupational related noise-induce hearing loss (Concha-
Barrientos et al., 2004; Nelson et al., 2005). Scientific documents have revealed that
cement factories in industrialized nations are among the occupations with high noise
levels (Kamal et al., 1989; Ologe et al., 2006; Lie et al., 2016). However, only a few
related researches have been carried out in developing countries on noise-induced
hearing impairment among factory workers.
Cement production in Nigeria is important for economic development as well
as development of infrastructure. In 2014, Nigeria enjoyed economic growth that was
complemented with investments from the cement industry. The policy of the current
administration is shifting towards the non-oil sector which entails focus on solid
minerals with Nigeria having a reasonable numbers of established cement factories
(Ndinwa et al., 2020). The numbers of this factory is expected to geometrically
increased and meet the rising demand of other African countries. However, the
working condition in Nigeria’s cement industry has received little or no attention with
serious lack of laws protecting workers welfare (Ologe et al., 2006). There are
documented evidence(s) that cement factory workers run the risk of exposure to high
intensity of noise at work with little or no preventive measures put in place (Morata
and Meinke, 2016). Also, to our knowledge, very few researches have been carried out
in this related area in Nigeria. Therefore, given the lack of studies about noise-
impaired health challenges in Nigeria; documenting occupational noise exposure
through scholarly studies of this nature and task that give rise to noise in cement
factories are of necessity to provide working documents that will enable decision
makers to ensure that measures to protect workers health are implemented. Hence,
the necessity of this study doubles. Thus, the aim of this study is to evaluate the
perceived effects from exposure to occupational noise pollution on hearing loss
among cement factory workers in Edo State, Nigeria.
II. Study area
This study was conducted on Bua cement factory workers in Edo State, Nigeria. The
cement factory is located at Afookpella, along the Abuja-Okene expressway. The
factory has an installed cement production capacity of about 3.5 million MT and
incorporated in 1964 as a State Government owned Cement Production Company;
and sold to Bua Cement Manufacturing Company in 2008 (Ndinwa et al., 2020).
Geographically, the factory is located at latitude 7016i North and longitude 6020i East
(see Figure 1). The factory services the cement demand of the south-south
geopolitical zone of Nigeria (Ndinwa et al., 2020). The cement factory is located in a
settlement that shares boundaries with Imiegele, Kominio, Iddo, Awuyemi, Okugbe,
Oku and Imekuri communities. Over the years, the factory has produced about 45
million tons of cement in excess and recognized as a giant in the employment of the
local people. Bua cement factory in Afookpella has a production unit which is
subdivided into: cement milling and blending, raw material crushing and processing,
🅔 CHUKUMAH, NDINWA & AKPAFUN
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clinker production, milling and packing of raw materials as well as storage and
transportation sections.
Figures 1: Map of Okpella showing the cement factory, Source: Ebiagwai, (2016)
III. Material and methods
This study adopted a descriptive cross-sectional survey design to evaluate the
perceived effects from exposure to occupational noise pollution on hearing loss
among Bua cement factory workers in Edo State, Nigeria. 183 factory workers who
were mainly males working at the different sections of the factory was sampled for
the study. To qualify as a participant to be sampled, the researchers ensured that only
workers whom have worked in the factory as well as being exposed to various degree
of noise for a minimum of two years were selected. Also, the researchers ensured that
factory workers selected as sample were entirely based on voluntary participation and
personal willingness through signing of the consent form for participation. Workers
with health history on ear infections, tumors, head injuries and surgeries, hearing
defects and those on ototoxic medication were excluded from the sample. A well
designed and structured instrument (questionnaire) was used to collect personal and
scientific information from the participants. The instrument was sectionalized into
four major aspects covering demographic data, general medical and hearing history
of workers; level of knowledge of factory workers on the impact of noise pollution
exposure and measured hearing protection device (HPD) used. To prevent
participant’s interference and personal influence on the data collected, the
researchers ensured that the instrument was administered under close supervision.
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For respondents that were illiterates, research assistants helped in reading the
questions and available answers as stated in the instrument while same time, assisted
in filling the questionnaire based on the response of the participants. A certified
audiologist from Ambrose Ali University Specialist Teaching Hospital, Irrua was used
to carry out hearing assessment and noise survey of the assessment room.
Participants were assessed on a daily base before the start of work at the factory. This
allowed the hearing organs to recover from any temporary threshold or fatigue that
might have occurred. Instruments used were calibrated to meet standard according
to the American National Standards Institute.
On the other hand, 35dB was measured by the certified audiologist with the
aid of a Wensen WS 1361 type 2 digital sound level meters as the background noise
level of the assessment room. The background noise level was regularly checked and
monitored at least twice a day throughout the study period. This was carried out to
ensure that it remain constant throughout the experiment. Otoscopy was performed
with a Welch Allyn 25020 clinical otoscope to physically examine and rule out ear
perforations, impact wax and ear pathologies. The mobility and pressure within the
middle ear was measure using a tympanometer. A 226 Hz stimulus tone was
introduced to the middle ear canal and the result plotted on the tympanogram. An
audiometer set at 8 different frequencies (250, 500, 1000, 2000, 3000, 4000, 6000 and
8000 Hz) was used to evaluate each ears of the participants and the audiometric test
results obtained evaluated, using the classification of hearing loss developed by Clark,
(1981). Responses from the sampled participants were computed, edited, coded and
analysed using SPSS version 21. Demographic data of participants were analysed
using descriptive statistics. Participants’ level of knowledge on effect of exposure to
noise pollution from the factory was presented in percentages and measures of
centrality as well as dispersion were statistically analysed and summarized in tabular
format. Student t -test was used to analyse the test of association between hearing
loss and work duration; whereas predictors of hearing loss was determined using
multinomial logistic regression model. All statistical significance were considered at
p<0.05.
IV. Ethical clearance
Ethical approval was sought from Edo State Ministry of Health’s ethical clearance and
approval committee. In addition to the approval, a formal letter of introduction
obtained from the Department of Industrial Safety and Environmental Management,
School of Marine Technology, Burutu, Delta State was presented to the management
of Bua Cement Manufacturing Company to seek permission for the study. Before the
commencement of the study, the consented participants were adequately briefed
with information about the study as well as the confidentiality of elicited information
from the participants were assured.
V. Results
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6
The results of the study as displayed in the various tables are presented in this
section. These result details include demographic characteristics of the sampled
respondents; percentage level of respondents usage of hearing protective devices
(HPDs), percentage level of factory workers’ knowledge on the relationship between
noise and health, distribution of tympanograms among the study respondents;
prevalence of pure tone average for right and left ears; and multiple regression
showing predictors of hearing status for right and left ears.
A. Socio-demographic and occupational characteristics of factory workers
Table 1 present the age, educational background, marital status, departments and
work experiences of the study participants. The participants ranged from 18 to 60
years with a mean of 37.54.83years. A higher percentage of participants 68(37.2%)
fell within the range of 31-40 years; this was followed by participants within the range
of 41-50 years which posses 58(31.7%) and age range of 18-30 years with 31(16.9%);
whereas participants within the range of 50+ had the least percentage 26(14.2%)
from the study. The entire participants used for the study were male. As observed
from the data displayed in Table 1, revealed that majority of the participants had
formal education with 73(39.9%) of the sample completed senior secondary school,
35(19.1%) of the study participants were first school leaving certificate holders;
30(16.4%) of them had either National Certificate of Education or the Ordinary
National Diploma certificate; 27(14.2%) of the sample were degree holders, whereas
participants with no formal education had the least percentage 18(9.8%). Ascertained
also from Table 1, was that each of the departments had equal participants (20.2%)
that were recruited for the study except for storage and transportation department
with slight decrease (19.1%). More so, it was revealed that out of 183 participants
studied, majority were married 89(48.6%); this was followed by participants that were
single 68(37.2%) and widows/divorcees 26(14.2%) were the least among the
participants.
The occupational profiles of the participants revealed that a larger number of the
participants were contract staff 115(62.8%), whereas the other 68(37.2%) of the staffs
were participants that were employed in the factory on a permanent bases. The data
analysis further revealed that 63(34.4%) of the workforce studied had worked in the
factory for 5-6 years; followed by participants 36(19.7%) whom have worked for 3-4
years; 32(17.5%) have worked in the factory for 4-5 years and 29(15.8%) of the sample
had worked for 6-7 years; whereas the other 23(12.6%) participants have been
engaged as staff with the factory for over 2-3 years.
B. The use of hearing protection devices (HPDs) by study participants at BUA
cement factory
Workers compliance to the use of hearing protection device as reported in Table 2;
revealed that higher percentage (55.8%) of the workforce studied uses HPDs while
working. Despite the reported statistics, it was revealed that 41.6% of the participants
had limited knowledge on the use of HPDs, 24.1% acclaimed that it was unnecessary
using HPDs, 17.3% of the sample attested that the use of HPDs during work makes
EUROPEAN JOURNAL OF INTERDISCIPLINARY RESEARCH 🅔
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them feel uncomfortable; whereas 5.2% of the participants attested that they do not
work in noisy environment. These affirmations by the participants further revealed the
reasons behind the nonchalant attitudes towards compliance to the usage of HPDs;
as it was recorded in Table 2 that 21.3% of the participants make use of HPDs always
while working; 25.8% of the sample sometimes make use of HPDs, whereas larger
percentage of the participants irregularly uses the device during work hours.
Table 1. Socio-demographic and occupational characteristic of factory workers
Variables
Frequency
Percentage
MeanSD
Age group
18-30
31
16.9
37.54.83
31-40
68
37.2
41-50
58
31.7
50+
26
14.2
Total
183
100
Education attainment
No formal education
18
9.8
First leaving certificate
35
19.1
Senior secondary school
73
39.9
NCE/ND
30
16.4
B.Sc/HND
27
14.8
Total
183
100
Marital status
Single
68
37.2
Married
89
48.6
Widow/divorced
26
14.2
Total
183
100
Employment status
Contract staff
115
62.8
Permanent staff
68
37.2
Total
183
100
Department
RMCP
37
20.2
MPRM
37
20.2
ST
35
19.1
CP
37
20.2
CMB
37
20.2
Total
183
100
Years of work
experience
2-3 yrs
23
12.6
3-4 yrs
36
19.7
4-5 yrs
32
17.5
5-6 yrs
63
34.4
6-7 yrs
29
15.8
Total
183
100
**RMCP = Raw material crushing & processing, MPRM = Milling & packing of raw materials ST= Storage &
transportation, CP= Clinker production CMB= Cement milling & blending
Table 2. The use of hearing protection device by factory workers at BUA cement factory
Response (%)
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Item
Yes
No
HPD use during
work
55.8
44.2
Always
Frequency
Sometimes
Infrequently
Frequency of HPD
21.3
7.6
25.8
45.3
It is
uncomfortable
Never thought
about it
It’s
unnecessary
Limited
knowledge
Do not
work in
noise
Justification for
irregular use of
HPDs
11.8
17.3
24.1
41.6
5.2
C. The level of workers’ knowledge on the relationship between noise and
health among the study sample
Investigation as displayed in Table 3 concerning knowledge level of workers on the
effects of noise on health revealed that 73.2% of the studied participants reported
that workplace noise levels affects workers health. Also, 26.8% of the participants
objected and attested that workplace noise levels have no health effects on workers.
More so, data analysis for the perception of workplace noise levels revealed that
higher percentage of the participants acclaimed that they perceived the noise levels
as high. This was followed by 35.6% of the participants who reported that the noise
level at the factory was average, whereas 22.1% of the sampled participants
acknowledged the factory noise levels to be very high. Majority of the participants
representing 93.4% acknowledged that workplace noise levels impacts on the hearing
loss of the workers. Further revealed in Table 3, was that 86.7% of the participants
acclaimed that workplace noise level lead to headaches on factory workers, whereas
13.3% of the participant disagreed with the assertion. This was followed by 78.4% of
the participants who reported as revealed from the filled questionnaires that
workplace noise level easily provokes workers temper, whereas 21.6% of them
disagreed. Opinion of the studied participants revealed that a higher percentage
(96.1%) of the respondents consented that high workplace noise level lead to loss of
workers’ concentration; however, a lesser percentage (3.9%) of the sample disagreed
that workplace noise level usually lead to loss of workers concentration.
Table 3. The level of workers’ knowledge on the effects of noise on health
Response (%)
Item
Yes
No
Workplace noise levels on health effect
73.2
26.8
Perception about workplace noise levels
Very high
High
Average
22.1
42.3
35.6
Effects of workplace noise levels
True
False
Hearing loss
93.4
6.6
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Headaches
86.7
13.3
Bad temper
78.4
21.6
Loss of concentration
96.1
3.9
D. Tympanometry
Tympanometry results of the participants are presented in Table 4. A critical study of
the result revealed that the entire subjects presented Type A tympanograms in 366
pairs of ears.
Table 4. Distribution of tympanograms among study participants at
BUA cement factory
Category of
Tympanogram
Number or ears
Percent %
Type A
366
100
Type B
0
0.0
Type C
0
0.0
Type AS
0
0.0
Type AD
0
0.0
Total
366
100
E. Prevalence of hearing loss among study participants
Table 5 presents details on the prevalence of hearing loss among study participants.
From the details as contained in the table revealed that the participants’ prevalence
of hearing loss at 0.5, 1 and 2 KHz for the right and left ears were 8.3% across board
respectively; whereas those of hearing loss at 3, 4 and 6 KHz for right and let ears
recorded were 22.6% and 23.2%.
Table 5. Prevalence of pure-tone averages for right and left ears
Hearing status
Right ear
Left ear
PTA512 (%)
PTA346 (%)
PTA512 (%)
PTA346 (%)
Normal hearing
91.7
77.4
91.7
76.8
Hearing loss
8.3
22.6
8.3
23.2
Total
100
100
100
100
MeanSD
13.611.8
21.98.3
12.47.5
21.29.7
Results of data analysis as shown in Table 6, revealed that at 3, 4 and 6 KHz, the
prevalence of hearing loss for participants from storage and transportation
department had the lowest percentage ratio (right =18.2%, left =19.7% ears) when
compared with figures of the prevalence of hearing loss from other departments,
RMCP (right =22.5%, left =24.2% ears), MPRM (right =23.7%, left = 26.9% ears), CP
(right = 25.5%, left =27.2% ears) and CMB (right =21.9%, left =26.4% ears).
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Table 6. Prevalence of hearing loss for the various study departments at BUA cement
factory
Hearing Status
Department
Levels
Right ear (%)
Left ear (%)
PTA512
PTA346
PTA512
PTA346
RMCP
Normal hearing
94.3
77.5
92.4
75.8
Hearing loss
5.7
22.5
7.6
24.2
MPRM
Normal hearing
86.4
76.3
88.6
73.1
Hearing loss
13.6
23.7
11.4
26.9
ST
Normal hearing
96.6
81.8
95.8
80.3
Hearing loss
3.4
18.2
4.2
19.7
CP
Normal hearing
84.9
74.5
82.2
72.8
Hearing loss
15.1
25.5
17.8
27.2
CMB
Normal hearing
91.7
78.1
85.4
73.6
Hearing loss
8.3
21.9
14.6
26.4
**RMCP = Raw material crushing & processing, MPRM = Milling & packing of raw materials ST= Storage &
transportation, CP= Clinker production CMB= Cement milling & blending
F. Test of relationship between the study variables
Statistics in Table 7, revealed a non-significant relationship between hours at work
and hearing status at PTA512 and PTA346 [χ2 (5, n= 366) = 0.62 and 1.08; p > 0.05] for
right ears.
Table 7. Relationship between hours at work and hearing status for right ears
Pure-Tone
Average
(PTA)
Hearing Status
Hours at Work
x2
df
p-value
5
6
7
8
PTA512
Normal hearing
42
56
56
182
3.46
5
0.62
Hearing loss
0
6
6
18
Total
42
62
62
200
PTA346
Normal hearing
42
50
46
162
5.41
5
1.08
Hearing loss
0
12
16
38
Total
42
62
62
200
Significant at 0.05
Also, similar statistics as shown in Table 8, revealed as well a non-significant
relationship between hours at work and hearing status at PTA512 and PTA346 [χ2 (5, n=
366) = 1.46 and 1.92; p > 0.05] for left ears.
Table 8. Association between hours at work and hearing status for left ears
Pure-Tone
Average
(PTA)
Hearing Status
Hours at Work
x2
df
p-value
5
6
7
8
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PTA512
Normal hearing
38
54
62
176
7.31
5
1.46
Hearing loss
4
8
0
24
Total
42
62
62
200
PTA346
Normal hearing
40
56
62
180
5.46
5
1.92
Hearing loss
2
6
16
20
Total
42
62
46
200
Significant at 0.05
Multiple regression analysis as displayed in Table 9, was used to test if variables such
as age, years of experience, departments and knowledge significantly predicted
hearing loss at PTA512 for right ears. The regression results revealed that 4 predictors
explained 8% of the variability [R2 = .07, F (4, 156) = 1.68, p > 0.05] in hearing loss,
which appears not to be significant. None of the variables tested significantly
predicting hearing loss at PTA512 for right ears. Furthermore, multiple regression
analysis was equally carried out to ascertain hearing loss at PTA346. This test was done
to ascertain if age, years of experience, departments and knowledge significantly
predicted hearing loss. The results revealed that the 4 predictors significantly
explained 28% of the variability [R2 = .32, F(4, 156) = 4.54, p < 0.05] in hearing loss. The
analysis revealed further that age (β = .56, p < 0.05) as an independent variable
significantly predicted hearing loss at PTA346 for right ears (see Table 10).
Table 9. Multiple regression showing predictors of hearing loss for right ears
at PTA512
PTA512
Predictors
R2
Beta
B
T
p-value
Constant
.07
9.42
1.61
.51
Age
.09
.84
.62
.16
Years of experience
-.01
-.01
-.01
.69
Department
.24
5.76
1.78
.93
Knowledge
-.05
-.34
-.29
.26
*Significant at 0.05
Table 10. Multiple regression showing predictors of hearing loss for right ears
at PTA346
PTA346
Predictors
R2
Beta
B
T
p-value
Constant
.32
13.14
3.37
.53
*Age
.56
5.21
2.92
.71
Years of experience
-.03
-.04
-.14
.78
Department
.07
.63
.75
.82
Knowledge
-.45
-.76
-.82
.46
*Significant at 0.05
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Statistical analysis as displayed in Table 11 was carried out to ascertain if age, years of
experience, departments and knowledge can significantly predict hearing loss at
PTA512 for left ears. The regression results revealed that 4 predictors explained 43% of
the variability [R2 = .39, F(4, 156) = 2.71, p > 0.05] in hearing loss; however, it indicated
not significant. None of the tested variables significantly predicted hearing loss at
PTA512 for left ears. More so, same type of multiple regression test was done to
predict hearing loss at PTA346for left ears; the results of the regression revealed that 4
predictors significantly explained 41% of the variability in hearing loss [R2 = .36, F(4,
156) = 2.52, p < 0.05]. The regression revealed further that age (β = .44, p < 0.05) as an
independent variable significantly predicted hearing loss at PTA346 for left ears.
Table 11. Multiple regression showing predictors of hearing loss for left
ears at PTA512
PTA512
Predictors
R2
Beta
B
T
p-value
Constant
.39
13.62
4.57
.95
Age
.31
2.48
2.73
.84
Years of experience
.15
.11
.86
.37
Department
.10
2.01
.62
.91
Knowledge
-.18
-.68
-2.06
.73
*Significant at 0.05
Table 12. Multiple regression showing predictors of hearing loss for left
ears at PTA346
PTA346
Predictors
R2
Beta
B
T
p-value
Constant
.36
15.07
3.35
.61
*Age
.44
5.49
2.42
.28
Years of experience
.16
.63
.17
.32
Department
-.107
-1.47
-.53
.71
Knowledge
-.15
-.92
-1.11
.26
*Significant at 0.05
VI. Discussion
Notable scholars from other parts of the world have affirmed high level of workplace
noise as a known health hazard affecting the physiological and psychological
functioning of human organs (Nelson et al., 2005; Ologe et al., 2006; Singh et al.,
2013). Most research surveys have focused mainly on determining the degree and
prevalence of hearing loss, surveyed noise levels at workplace, assessed the
relationships existing between working hours cum exposure and hearing loss.
However, this study was carried out to evaluate the perceived effects from exposure
to occupational noise pollution on hearing loss among Bua cement factory workers in
Edo State using pure tone audiometry, tympanometry, otoscopy and questionnaire.
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13
The survey revealed that the workers sampled were all males. This finding may be
adduced to the nature of the occupation which requires physical strength for
standing and operating of machineries. This finding is in line with the submission of
Bisong et al. (2004). It also corroborates the report by Yesufu (2012) that larger
proportion of male respondents take up occupation in the manufacturing industry
than their female counterparts. The most prevalent age range was 31-40 years
(37.2%) and 41-50 years (31.7%). This may be attributed to the fact that in Nigeria
younger and experienced individuals of these age range are more needed in the
manufacturing industry than any other age range. Higher percentage of the
workforce sampled were literates as majority (90.8%) had one form of formal
education and certification or another.
Investigation into the level of compliance in the usage of hearing protection
devices among the participants was essential because of the opportunity to
understand and amend the inadequacies in noise exposure reduction efforts in the
factory. The survey analysis revealed that workers percentage level on the general
usage of hearing protection devices was high. This finding was ascertained as 55.8%
reported its usage during working hours. Specifically, 21.3% of the participants make
use of HPDs always; this was followed by 25.8% of the sample which claim to
sometimes make use of the device; however, larger percentage (45.3%) of the
participants irregularly uses the device during working hours. The study further
revealed that 41.6% of the participants had limited knowledge on the use of hearing
protection devices; 24.1% acclaimed that the use of HPDs was unnecessary, 17.3%
attested that using HPDs during work hours make them feel uncomfortable, whereas
5.2% confirmed not to work in noisy environment as the reason behind their non
usage of HPDs. The reasons adduced by the participants revealed their level of
awareness and understanding on the benefits of HPDs. These results are similar with
the results reported by Ali et al. (2012). They reported 14.5% for unavailability of
HPDs, 6.6% for HPDs not necessary, 11.8% for discomfort and 2.6% for limited
knowledge. These findings also affirmed the results reported by Mndema and Mkoma
(2012) that about 15% of workers in Tanzania cement factory do not always make use
of HPDs because they lack proper awareness and understanding of its effective on
the protection of hearing organs. More so, similar findings were reported in a survey
research conducted on firefighters and documented by Hong et al. (2008). NIOSH
(1998) mandated employers to train and retrain workers on how to appropriately
select, fit and use hearing protection devices. The findings of this study necessitate
the urgent need for occupational and safety laws that would ensure that employers
protect their employees by providing the necessary safety gadgets and equipment as
well as enforcing compliance on usage among employees. Furthermore, the design
and implementation of an awareness and training programs to further educate
workers on the benefits of using HPDs and other safety gadgets as well as the
demerits would go a long way to curb occupational injuries and disabilities.
This study revealed that a sizeable percentage of the participants at the
cement factory studied exhibited in-depth knowledge on the impact of noise on
workers’ health. This was made known as the results displayed in Table 3 confirmed
🅔 CHUKUMAH, NDINWA & AKPAFUN
14
that 73.2% as against 26.8% of the studied participants reported that workplace noise
levels affect workers health. More so, the data which sought to enquire on the
participants’ perception of workplace noise levels revealed that majority perceived
noise level as high. Responses from the participants also revealed that larger
proportion of the sample representing 93.4% acknowledged that workplace noise
level impacts on the hearing loss of workers. Furthermore, 86.7% of the participants
acclaimed that workplace noise levels caused headaches, 78.4% affirmed easy
provocation of worker’s temper and 96.1% consented to loss of worker’s
concentration. The overwhelming responses of the participants could be as a result of
the workers experiencing such effects from workplace noise levels. This report
affirmed the findings by Bisong et al. (2004); Yesufu (2012) and Ali et al. (2012). It was
also in conformity with the figures; 20.5% for headaches, 53.8% for hearing problems
and 17.9% for irritability as a result of exposure to workplace noise which was
reported by Mndema and Mkoma (2012). The finding from the study as well revealed
that higher percentage of the participants were knowledgeable on the preventive
measures such as work rotation; however, the practice of these measures was not
reflected in their day-to-day task.
Also worthy of notice is that the entire study participants were subjected to
middle ear evaluation with tympanometer. The result revealed that the participants’
ears tested were presented with Type A tympanograms. This was a confirmation of
normal middle ear pressure and tympanic membrane mobility in the ears tested.
Pure tone audiometry was carried out to assess the ears of 183 participants.
The audiometry was done on both ears of the participants. The PTA was calculated
over a frequency of 0.5, 1 and 2 KHz for both ears and the PTA for the ears was added
up and then hearing values compared to standard (≤50). The prevalence of hearing
loss at PTA512 (0.5, 1 and 2 KHz) was revealed to be 8.3% for right and left ears as well
as 22.6% for right ears and 23.2% for left ears at PTA346. This finding revealed that
most of the participants are presented with a high frequency of hearing loss.
Shakhatreh et al. (2000) in a study carried out among workers in a textile factory
revealed elevated levels of hearing loss among respondents with continuous
exposures. Their report revealed an increase in hearing loss (39%) among workers
who had worked for 25 years or more in the textile factory. In a similar study by
Osibogun et al. (2000), a significant hearing loss among workers exposed to noise in
a textile factory in Logos was recorded. Their findings revealed significant threshold
shifts at 4000 Hz among the group exposed to noise. Also, a positive correlation
between increased hearing threshold levels and duration of exposure were reported.
Boateng and Amdofu (2004) in a study determined the effects of industrial noise
pollution on the hearing acuity of workers in Ghana. They reported the prevalence of
hearing loss to be 23%, 20% and 7.9% among respondents at corn mills, saw mills
and printing press respectively. It was revealed in their study, that noise levels at saw
and corn mills exceeded 90 decibels.
Participants from storage and transportation (ST) department had the lowest
prevalence of hearing loss at PTA512and PTA346 when compared with participants from
EUROPEAN JOURNAL OF INTERDISCIPLINARY RESEARCH 🅔
15
other departments. This may be adduced to the degree in levels of noise exposure in
the aforementioned departments. This finding was consistent with the report by
Yabani (1995); who reported a significant higher prevalence of hearing loss among
employees of a milling department. No significant relationship existed between the
hours at work and hearing status for both ears at PTA512 and PTA346. This may be
attributed to the fact that majority of the study participants have not worked more
than 6 years in the factory. This finding was not inconformity with the report by
Yabani (1995); who demonstrated that workers who spent at least 5 years in cement
manufacturing company exhibited symptoms of noise induce hearing loss. Further
revealed from the regression analysis was that no significant relationship existed
between the selected predictors and hearing loss for both ears at PTA512. However,
age was revealed as a significant predictor of hearing status at PTA346 for both ears.
The relationship established between age and hearing status was positive. The
implication of this finding was that older workers presented more severe hearing loss
than the younger counterparts. Noticeable researchers in other parts of the world
have demonstrated similar findings of hearing loss due to ageing. However, it has
remained unclear and difficult to ascertain till date, the relationship between noise-
induced hearing loss and age-related hearing loss. This may be due to the fact that
age-related hearing loss is caused by several factors (Rosenhall, 2003).
VII. Conclusion
This cross-sectional survey study sought to evaluate the perceived effects from
exposure to occupational noise pollution on hearing loss among Bua cement factory
workers in Edo State, Nigeria. The study specifically evaluated the percentage ratio of
compliance on the use of hearing protection devices by workers during working
hours, worker’s level of awareness on the effects of noise, attitude of workers toward
the use of hearing protection device, prevalence of hearing loss among workers,
relationship between years of engagement at the factory and hearing status of
workers. The results from the analysis of field data revealed that a larger proportion
of the study participants demonstrated higher percentage level of awareness on the
effects of noise on health. Greater number of participants revealed higher percentage
on the general usage of hearing protection device; and further revealed, was that
most of the participants presented high frequency of hearing loss. Participants from
the storage and transportation (ST) department had the lowest prevalence of hearing
loss at PTA512 and PTA346 when compared with participants from other departments.
No significant relationship was established to exist between the hours at work and
hearing status for both ears at PTA512 and PTA346. Further revealed from the multiple
regression analysis was that no significant relationship existed between the selected
predictors and hearing loss for both ears at PTA512. However, age was revealed as a
significant predictor of hearing status at PTA346 for both ears because a positive
relationship was established between age and hearing status.
VIII. Recommendations
🅔 CHUKUMAH, NDINWA & AKPAFUN
16
The following recommendations were made by the researchers based on the findings
of the study
1. Workers should be equipped adequately with effective and functional hearing
protection devices.
2. Workers engaged in departments where noise level exceeds 100 dB should be
provided with double fitted hearing protection devices to sufficiently reduce the
effects from the exposure.
3. Routine training programmes should be developed and implemented by
employers in order for workers to be equipped intellectually on the benefits of
practicing safety at work
4. Employers should ensure that workers are effectively monitored on the use of
hearing protection devices and as well spell out penalties for defaulters.
5. Pre-employment and post employment assessment of workers hearing organs
should be carried out effectively.
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Funding
No external, third-party or private sector funding to report.
Notes on Contributors
Charity O. Chukumah is a senior lecturer in the Department of Industrial Safety &
Environmental Management, Delta State School of Marine Technology, Burutu, Nigeria. She is
currently on her PhD research programme at the Department of Microbiology, University of
Benin, Edo State. She holds a Master of Science in Environmental Microbiology & Public
Health, University of Benin; Master of Science in Environmental Management, Imo State
University of Science & Technology, Owerri. She is a Member, Nigeria Environmental Society
(MNES) & Member Corporate Institute of Risk & Safety Management (MIRSM). She has been
lecturing undergraduate students courses on microbiology, public health safety and
environmental issues. Her research interests include public safety, waste management and
EUROPEAN JOURNAL OF INTERDISCIPLINARY RESEARCH 🅔
19
pollution studies. She has presented several articles in conferences and published over
fourteen articles both in national and international scientific journals.
Gabriel C. C. Ndinwa is a Lecturer II in the Department of Industrial Safety & Environmental
Management, Delta State School of Marine Technology, Burutu. He is a doctoral student at
the Faculty of Environmental Sciences, Nnamdi Azikiwe University, Awka. He holds a National
Diploma in Health, Safety & Environmental Education, & B.Sc Environmental Science, both
from Delta State University, Abraka; M.Sc Environmental Quality Management, University of
Benin, Nigeria. He is a Member, Corporate Institute of Risk & Safety Management (MIRSM),
Member Asia-Pacific Chemical, Biological & Environmental Engineering Society (APCBEES),
Member Nigeria Institute of Science Laboratory Technologists (NISLT), Member Nigeria
Institution of Environmental Engineers (NIEE) & Member, Wastes Management Society of
Nigeria. He has attended & presented several scholarly researched articles at both national &
regional conferences & has published over twenty-two articles in scholarly journals. His
research & teaching focuses on environmental management issues, safety & health, quality
control, waste management, EIA & pollution studies.
Solomon A. Akpafun holds a Master of Science Degree from University of Benin, Nigeria;
B.Sc Geography from University of Port Harcourt, River State & N.C.E Geography/Biology
from College of Education, Warri, Delta State. He is a senior lecturer at the Department of
Urban & Rural Planning, Delta State School of Marine Technology, Burutu, Nigeria. His
research area covers urban management challenges, land use planning, waste management,
climate change & adaptability, social dimension of natural resource management,
geospatial science & modeling. He has published a number of research articles both in
national & international scientific journals.
