research article noise exposure and hearing capabilities

Research ArticleNoise Exposure and Hearing Capabilities of Quarry Workers inGhana A Cross-Sectional Study

Charles Kwame R Gyamfi1 Isaac Amankwaa2 Frank Owusu Sekyere3 and Daniel Boateng4

1Center for Disability and Rehabilitation Studies Department of Community HealthKwame Nkrumah University of Science and Technology Kumasi Ghana2Department of Nursing Garden City University College Kumasi Ghana3Department of Interdisciplinary Studies University of Education Kumasi Ghana4Department of Community Health Kwame Nkrumah University of Science and Technology Kumasi Ghana

Correspondence should be addressed to Daniel Boateng kingdanniegmailcom

Received 22 July 2015 Accepted 21 December 2015

Academic Editor Benny Zee

Copyright copy 2016 Charles Kwame R Gyamfi et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

IntroductionAlthough quarry operations have high economic significance the effects they cause to theworkers in terms of excessivenoise production cannot be overlooked This cross-sectional study assessed the extent of noise exposure and its influence onhearing capabilities among quarry workers in Ashanti region Methods The study involved 400 workers randomly selected fromfive quarries in Ashanti region from April to June 2012 Data was collected using structured questionnaires physical examinationand audiological assessments A logistic regression model was fitted to assess independent predictors of hearing loss Results Allthe machines used at the various quarries produced noise that exceeded the minimum threshold with levels ranging from 855 dBAto 1027 dBA 176 (44) of study respondents had hearing threshold higher than 25 dBA 18 and 2 of these were moderately(41ndash55 dBA) and severely (71ndash90 dBA) impaired respectively Age duration of work and use of earplugs independently predictedthe development of hearing loss Use of earplugs showed a protective effect on the development of hearing loss (OR = 045 95 CI= 025 084) Conclusion This study provides empirical evidence on the extent of damage caused to quarry workers as a result ofexcessive noise exposure This will support the institution of appropriate protective measures to minimize this threat

1 Background

Occupational health is an important public health concernfor the working population [1] Various aspects of the work-ing environment could expose an individual to potentialhazardous elements Noise is considered as one of thesepotential hazards and it is currently seen as a global healthconcern Noise which is defined loosely as annoying soundsis part of the everyday human activity Excessive noise beyondtolerated levels from all these sources is hazardous and couldcause hearing impairmentThis is a widespread occupationalhazard which could result in noise-induced hearing loss(NIHL) Other associated health effects include elevatedblood pressure sleeping difficulty annoyance and stress andtemporary threshold shift (TTS) [2 3]

The growing attention for NIHL is due to the factthat unlike many injuries or illnesses hearing loss may bepermanent and irreversible Exposure to excess noise is firstobserved as an increase in the threshold of hearing (thresholdshift) as assessed by audiometry [3] This is defined as achange in hearing thresholds of an average 10 dB or moreat 2000 3000 and 4000Hz in either ear (poorer hearing)[4] There are two types of NIHL a temporary thresholdshift which is a temporary loss of hearing and a permanentthreshold shift which involves a shift in the personrsquos ability tohear soft sounds This is as a result of long-term exposure toloud sounds of slightly lower intensity such as factory noiseor rock music

Although noise is associated with almost every workactivity some activities are associated with particularly high

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2 Journal of Environmental and Public Health

levels of noise In general sounds above 85 dB are consideredharmful depending on how long and how often one isexposed to them and whether you wear hearing Previousliterature shows that workers in mines quarries sawmillstextile factors printing presses and many others work withmachines that produces noisemuch higher than the toleratedlevels and therefore expose workers to potential hearing loss[5ndash7] In the large coal industry about 76 are exposedto hazardous noise [8] This causes about 25 of severehearing problems and about 80 of hearing impairment inthe workersrsquo retirement age [8]

Although the situation could be improving in developedcountries as a result of more widespread appreciation of thehazard and the institution of protective measures evidencefrom developing countries suggests that average noise lev-els are well above the occupational level recommended inmany developed nations [9 10] Increasing industrializationmight exacerbate this situation in developing countries andtherefore the need to assess the industrial noise pollutionand its impact on the hearing capabilities of workers in suchareas

In Ghana there is very little data on the effect ofnoise exposure on quarry industrial workers More so theincreasing number of patients seeking medical attention fortheir ears atHearingAssessmentCentre at theKomfoAnokyeTeaching Hospital (KATH) in Kumasi between 1995 to 1998[11] has called for the need to focus attention on noisepollution on workers in the industrial settings such as quarryindustries Furthermore no study has focused specifically onoccupational hearing loss among workers of quarry indus-tries even though the impact of noise pollution on hearingin mining company has been studied [11] This study seeks toprovide empirical evidence on the extent of noise exposureand its influence on hearing capabilities of workers in thequarry industry This would help in formulating policies andinstitute preventive measures that will help minimize the riskof occupational hearing loss among the exposed population

2 Methodology

21 Study Design and Settings This was a descriptive cross-sectional study conducted in Kwabre East District of Ashantiregion of Ghana Kwabre District carved out of the formerKwabre Sekyere District in 1988 is located almost in thecentral portion of Ashanti region It is within latitude 6∘4410158401015840north and longitude 1∘3310158401015840 to 1∘4410158401015840 west The district sharescommon boundaries with Afigya-Sekyere District to thenorth Kumasi metropolitan area to the south Ejisu-JuabenDistrict to the southeast Atwima District to the west andOffinso District to the northwestTheDistrict has a total landarea of 2468 square kilometers constituting about 101of thetotal land area of Ashanti region Kwabre District is part ofthe Greater Kumasi City region which is made up of KumasiMetropolitan Area and the surrounding Districts Accordingto 2000rsquos population and housing census the district has atotal population of about 205372 people The physiographyof the area consists of scarps formed by the extensive quarryactivities going on in the areaThemain land usage in the areacan be categorized into stone quarrying and agriculture The

quarries are mainly located near the mountains where gran-ite deposits have been detected The quarry developers leasethe land from the owners at a fee until the time the quarrywork is finishedThemain commercial purposes of quarryingare building stones and quarry dust Agricultural activities inthe area are mostly subsistence and cash crop farming

22 Study Population and Sampling The study populationwas drawn from workers of the five (5) quarry companiesnamely Northern mine quarry A Kannin mine Taysecquarry company KAS quarry company and Siemens quarrycompany Workers who have been working at the respectivequarry for more than six months were included in the studyWorkers who had previous history of hearing loss and thosenot directly involved in the quarrying process were excludedThe study comprised 400 workers from the various quarrycompanies The composition of respondents from the quarrycompanies was as follows A Kannin (120 respondents201) KAS quarry (80 respondents 134) Siemens quarry(60 respondents 10) Taysec (40 respondents 67) andNorthern mines and quarry (98 respondents 164)

The surveys were conducted from April to June 2012Based on the average number of clients per day for a specificfacility and the desired sample size a recruitment interval119896 was developed for each quarry Based on this interval the119896th worker was interviewed on each interview day until therequired sample size was reached for each quarryThe admin-istration of the study was focused mainly on the industrialnoise pollution and its impact on the hearing capabilities ofworkers The desired sample size was calculated based onKirkwood and Sterne [12] assuming a 40proportion for theevent of interest and 10 nonresponse rate

23 Data Collection Techniques and Instruments Data werecollected mainly through interviewing Participants weregiven consent form to sign and had all their concerns andquestions answered before data collection began All toolsemployed in the research were developed using standardprocedures pretested and revised to ensure their validityand reliability and research assistants were trained to ensureuniformity in the administration of questionnaires Thevarious instruments used for measuring sound levels werethe Casella sound level meter (in the recording of the noiselevels in the various companies) and pure-tone audiometer(to evaluate the hearing threshold of subjects)

231 Casella Sound Level Meter Theweighted networks in ameter are electronic circuits whose response to low frequen-cies and to very high frequencies is reduced in a specifiedmanner In general four different weightings have been stan-dardized internationally as A B C and D Network A is usedin industrial setting and this was used throughout the studyTo check for vibration shock and excessive heat a calibratorwas attached to the microphone of the meter and the readingwas then compared with the calibratorrsquos valueThemeter wasadjusted when required to bring it into calibration

232 Pure-Tone Audiometry A biologic calibration of thepure-tone audiometer was performed daily using supposedly

Journal of Environmental and Public Health 3

normal people with normal hearing prior to any audiologicalevaluation of the subjects An otoscopic examination wasalso performed on each subject to exclude wax or anydischarge in the ear canal or perforation of the eardrum torule out possibility of conductive hearing loss To overcomebias on the hearing acuity by ambient noise influencefive (5) of the subjects each from the various companieswere randomly selected to undergo audiometric retestingat Hearing Assessment Centre at Komfo Anokye TeachingHospital (KATH) The hearing thresholds obtained for thesegroups were found not to be different from those obtainedwithin the premises of the factories Audiometric tests wereperformed on employees working in the area with noise levelexceeding the threshold limit value of 85 dBA using screeningAudiometer (AS608) obtained from the Hearing AssessmentCentre of the Department of Ear Nose and Throat (ENT)of KATH Hearing acuity was measured at 5 dBA intervalover a range of octave band frequencies from 500 to 8000HzHearing was considered normal if the threshold level wasless than or equal to 25 dBA at the frequencies 250 5001000 2000 4000 and 8000Hz However the intensity of thestimuli was increased beyond 25 dBA at any frequency untila response was obtained Individuals with a characteristicnotch of four (4) KHz depicting the classical sign of NIHLwere analysed The degree and type of hearing loss werealso determined using Goodmanrsquos [13] and Carhartrsquos [14]approaches respectively Both ears of each subject were testedto establish pure-tone hearing sensitivity All subjects weretested at the beginning of each work shift to ensure that thosewhose hearing had been ldquofatiguedrdquo might have gained somerecovery after being away from the noise exposure

24 Description of Variables and Data Analysis The outcomevariable was hearing threshold (dBA) Hearing thresholdbeyond 25 dBA is classified as having hearing loss and hearingloss was further classified based on its severity (26ndash40 dBAmild 41ndash55 dBA moderate 56ndash70 dBA moderate-to-severe71ndash90 dBA severe and above 90 profound)The explanatoryvariables were age duration of exposure gender and use ofearplugs The response of each subject and the data obtainedfrom the administration of the physical instruments werescrutinized carefully and categorized in tables and graphsData was analyzed with R 311 [15] The analysis involved adescription of the baseline characteristics of respondents andthe noise levelsmeasured on variousmachines at the quarriesA chi-square test was conducted to see the associationbetween workplace and hearing loss Logistic regressionanalysis was done to look at the influence of age durationof exposure and use of earplugs on the odds of hearing lossamong the quarry workers Significance of associations wasat 119901 value of lt005

241 Model Estimation and Assumptions A correlationbetween age and duration of exposure was assumed andtested using Pearsonrsquos correlation This was because the vari-able appeared to be approximately normally distributed Theexplanatory variables included in the model were also testedfor collinearity using the variance inflation factor (VIF) Thechoice of best-fittedmodelwas based onAkaikersquos Information

Criterion (AIC) This was proposed by Akaike [16] as ameasure of the goodness of fit of an estimated statisticalmodel It takes into account both the statistical goodness offit and the number of parameters that have to be estimated toachieve this particular degree of fit by imposing a penalty forincreasing the number of parametersTheAIC is given asminus2lowast(log likelihood)+2lowast (number of parameters in the model)that is minus2119871 + 2119901 Lower AIC is an indication of a betterlikelihood

25 Ethical Consideration A written permission was soughtfrom the management of the various quarry companies andethical clearance was granted by the Committee for HumanResearch and Population Ethics (CHRPE) at the School ofMedical Science (SMS) of the Kwame Nkrumah Universityof Science and Technology (KNUST) and Komfo AnokyeTeaching Hospital Kumasi

3 Results

31 Background Characteristics of Respondents Majority ofthe respondents were males (814) The mean age (SD) ofthe respondents was 417 (920)Most of the respondents wereChristians (59) and about 29 were Muslims With respectto their level of education 472 had junior secondary ormiddle school education About 17 had tertiary educationand 14 (23) had no formal education Majority had workedin the quarry for up to 10 years and 247 had worked in thequarry for less than 5 years 132 (33) of the respondents usedearplugs and 61 of respondents who wore no earplugs hadhearing thresholds above 25 dB as against 36 among thosewho wore earplugs

32 Noise Measurement at Various Facilities under Study Allthe companies had different production units with more orless the same type of machinery Table 1 displays the noiselevels obtained from the machines in the various companiesThe measurement values range from 855 dBA to 1027 dBAdemonstrating that the noise levels produced exceed thelimiting threshold level of 85 dBA It was realized that all thefive companies visited produced an excessive amount of noisecapable of damaging the hearing status of the workers

33 Hearing Thresholds at Various Quarries The meanhearing threshold among all workers was 2732 dBA and176 respondents (44) had hearing thresholds higherthan 25 dBA Comparatively a higher mean threshold wasobserved among workers at Taysec company (2998 dBA) fol-lowed by Northern mines and quarry (2643 dBA) (Table 2)More than 50 of respondents from Taysec company andKAS company had hearing threshold of more than 25 dBA(58 and 69 resp) The proportion of respondents withhearing threshold gt 25 dBA was comparatively low amongA Kannin and Siemens (29 and 33 resp) This differ-ence in hearing thresholds among respondents from variousworking environments was statistically significant (119901 lt0001) indicating the influence of the working environmenton the hearing threshold of a respondent As shown inFigure 1 majority of the respondents had mild hearing loss


Table 1 Measured noise levels (in dBA) on selected machines in five quarry companies

Type of machinesQuarry companies

A Kannin Kas Taysec Northern quarry SiemensdBA dBA dBA dBA dBA

Drilling machine 894 962 950 970 949Tyre wrench 870 863 879 885Lathe machine 874 865Block making machine 1003Generator set 865 979 879 943Crusher machine 996 1025 1013 1004 1027Primary processing machine 899 910 980 968 988Secondary processing machine 886 867 953 885 920Excavator machine 971 956 949 895 886Air compressor 874 869 932 954

Table 2 Hearing threshold levels among various groups of respondents

Category of workersTest results at 4 kz

Chi square119901 valueMean HTL HTL le 25 dBA HTL gt 25 dBA

119873 () 119873 ()Quarry workers

KAS 3391 25 (31) 55 (69) 3637Siemens 2422 40 (67) 20 (33)A Kannin 2433 85 (71) 35 (29) 119901 lt 0001

Taysec 2998 17 (43) 23 (58)Northern 2643 57 (57) 43 (43)

Total 2732 224 (56) 176 (44)HTL hearing threshold level

Table 3 Logistic regression analysis of predictors of hearing loss (HTL gt 25 dB) among quarry workers

Univariable MultivariableVariables Model 1 Model 2

OR [95 CI] AIC AORsect[95 CI] AOR$

[95 CI]Gender (ref = male) 079 [037 168] 54956Age 108 [105 111]lowastlowastlowast 50927 115 [108 124]lowastlowastlowast 115 [107 124]lowastlowastlowast

Duration of exposure 128 [119 137]lowastlowastlowast 48937 196 [120 323]lowastlowast 201 [119 339]lowastlowast

Age lowast duration of exposure 100 [100 101]lowastlowastlowast 47538 099 [098 099]lowast 099 [098 099]lowast

Ear plug (ref = number) 047 [028 077]lowastlowast 42049 046 [026 080]lowastlowast 040 [022 071]lowastlowast

AIC = 34319 AIC = 32856lowast

119901 lt 005 lowastlowast119901 lt 001 lowastlowastlowast119901 lt 0001sectAdjusted for type of quarry (place of work)$Adjusted for type of quarry (place of work) and family historyVIF = age (1244) duration of exposure (1250) ear plugs (1047)

(132 out of 176 respondents) Thirty-two respondents (18)had moderate hearing loss whereas 4 (2) respondents hadsevere cases of hearing loss

34 Influence of Age Duration of Exposure and Use ofEarplugs on Hearing Capabilities of Quarry Workers Table 3presents results of the univariable and multivariable logisticregression analysis of factors influencing hearing loss amongquarry workers Two models were fitted in the multivariable

analysis In model 1 the place of work was adjusted forwhile model 2 involved adjusting for place of work as wellas adjusting for family history of hearing loss The scatterplotof age and duration exposure showed a positive correlationwhich was slightly moderate (119903 = 0465) (Figure 2) The VIFfor all variables (shown under Table 3) were very low andimplied little or no existence of multicollinearity To this endall variables and an interaction between age and duration ofexposure were included in the multivariable analysis Based


75

185 2 00

10

20

30

40

50

60

70

80

()

Level of hearing impairment

Degree of hearing impairment among quarry workers

26ndash4

0(m

ild)

41ndash5

5(m

oder

ate)

56ndash7

0(m

oder

ate-

to-s

ever

e)

71ndash9

0(s

ever

e)

91+

(pro

foun

d)

Figure 1 Level of hearing impairment among quarry workers

Noi

se ex

posu

re

Age

15

10

5

0

20 30 40 50 60

Figure 2 Scatterplot of age versus duration of exposure

on the AIC the best-fitted model (ie the model with thelowest AIC) in themultivariable analysis was amodel withoutgender

Age duration of exposure and use of earplugs signifi-cantly predicted hearing impairment among quarry workers(Table 3) In the univariable analysis an increase in the ageof quarry workers by one year resulted in 8 increase inthe odds of hearing impairment (OR = 108 95 CI = 105111) The odds of hearing impairment with respect to ageincreased to 115 in themultivariable analysis where the placeof work was adjusted for and it remained unchanged inmodel 2 In model 1 an increase in duration of working atthe quarry by one year results in about two times increasein the odds of hearing impairment (OR = 196 95 CI =12 323) The strength of association however increasedin model 2 indicating a possible confounding effect of thevariables adjusted for in the association between durationof exposure and hearing impairment The use of earplugsshowed a protective effect on the odds of having hearing loss

In model 1 use of earplugs resulted in 54 decrease in oddsof having NIHL (OR = 046 95CI = 026 080) and this didnot change much in model 2 (OR = 040) The interactionbetween age and duration of exposure was just significantwith 119901 value of 005

4 Discussion

Occupational health is an important concern of the workingperson Various elements concerning a personrsquos workingenvironment can predispose one to developing a diseaseprocess Quarries are such organizations with high noiseproduction levels as a result of their activities The aim ofthis study was to look at NIHL among quarry workers inAshanti region of Ghana This study found a high prevalenceof hearing impairment among the quarry workers and allmachines used at the various sites produced noise levels thatexceed the limiting threshold

41 Noise Measurement at Various Facilities under StudyResults from this study indicate that all companies studiedhave different production units with similar type of machin-ery and the noise levels ranged from 855 dBA to 1027 dBAThis reveals that all the machines used at the various com-panies produced sound that exceeds the minimum thresholdof 85 dBA as recommended by World Health Organization[17] thereby having the potential of damaging the hearingstatus of workers These noise levels also exceed the limitset by the Ghana Environmental Protection Agency (EPA)under the EPA Act of 1994 (Act 490) [18] which permits lightindustrial areas 70 dB during the day and 60 dB at night andheavy industrial areas 70 dB noise during the day and 70 dBnoise at night Consistent with this study other studies fromdifferent countries reported exposure to high levels of noisepollution at theworkplaceThis includes the study by Ismail etal [5] among quarry workers inMalaysia where sound levelsexceeded the level that may cause NIHL to the workers

These however might not be limited to quarries aloneStudies on noise levels from other work settings includingthe study in Ghana by Boateng and Amedofu [6] on theimpact of noise levels on hearing capabilities of workers insaw mills corn mills and printing houses revealed that noiselevel in corn mills exceeds the limiting value Similarly astudy of working industries in Ethiopia by Mulugate [7] alsoreportednoise levels higher thanpermissible levels of 90 dBAOther studies from industrialized countries also indicate anoverexposure to high noise levels among coalminers [8 19]These noise levels are however potentially hazardous andmight result in hearing impairment among workers in thatenvironment

42 Noise Exposure and Hearing Loss This study revealedthat 44 of the quarry workers had hearing thresholdsof more than 25 dB This was however higher than theother prevalence reported from Sudan [20] 306 andfrom studies by Amedofu [11] 230 and Boateng andAmedofu [6] 230 On the other hand higher prevalencewas observed by Chaddha and Singh (500) [21] and Hong


(600) [22] Three out of the five companies involved inthe study also recorded a mean hearing threshold level ofmore than 25 dBA All the companies had more than 25of their respondents having NIHL with the percentage beinghighest amongworkers at KAS quarryTherewas a significantassociation between the various working environments andHTL and this could be due to the type and quantities of noisegenerating equipment used in the various quarries and howthese influence hearing capabilities Analysis of the extent ofhearing loss among respondents with HTL gt 25 dB indicatedthat 75 18 5 and 2 had mild moderate moderatelysevere and severe hearing loss respectively These indicatethe extent of ear damage caused to workers in severelynoise-exposed environments like the quarry and the need toinstitute appropriate interventions to curb this

43 Relationship between Age Duration of Exposure and Useof Earplugs and Hearing Loss among Respondents Generallythere is an established association between the age of workersand hearing loss [23ndash25] In this study increasing age ofquarry workers was associated with increasing odds of hear-ing loss among the quarry workers This is consistent withthe findings of an industry-specific study in USA [25] whichshowed that 90 of coal miners have hearing impairmentby the age of 52 years Also it is estimated that 70 of malemetalnonmetal miners will have hearing impairment by theage of 60 years [26] In the study by Ahmed et al [27] agewas the secondary predictor of hearing loss among workersin two plants in eastern Saudi Arabia

The study also revealed a significantly positive associa-tion between duration of work at the quarry and hearingimpairment According to theUnited StatesNational Instituteof Deafness and Other Communicable Disorders [28] longor repeated exposure to sounds at or above 85 decibels cancause hearing loss The louder the sound is the shorter thetime period before NIHL can occur becomes Duration ofexposure to noise at the working environment showed strongpositive relationship with the hearing threshold amongrespondents in the multivariable analysis

Wearing earplugs or other protective devices has beenrecommended for individuals involved in a loud activityThe proportion of respondents with hearing impairmentwas higher among those who did not wear earplugs Themultivariable analysis showed that use of ear protectiondecreased the odds of having hearing impairment amongquarry workers This is consistent with the outcome of thestudy by Hong [22] which found an inverse relationshipbetween hearing protector use and hearing status of theemployee Ahmed et al [27] also showed that wearinghearing protection devices is among the important factorsthat influence the measured hearing threshold values atlow frequencies Subjects who did wear hearing protectiondevices had lower measured hearing threshold values thansubjects who did not wear hearing protection According to aWHO bulletin on environmental burden of disease [3] thefirst priority in minimizing hearing loss is to reduce noisethrough technical measures such as introducing hearingprotection for workers when engineering controls are notapplicable or are insufficient It was however advocated that

the protective equipment must be properly selected wornand maintained

5 Limitations

Although the study accessed the exposure to noise theremight still be other underlying factors which might havecontributed to hearing loss These sources of noise producewhat is called sociocusis and their effect on hearing lossmightnot differ from occupational hearing loss [1] The authorsbelieved that the inclusion of variables on other sources ofloud noise measured major external sources of noise thatcould contribute to noise induced hearing lossTherewas alsoa possibility of recall bias with respect to previous history ofhearing problems Research assistants were however trainedto ensure comparability in the administration of question-naires across the study centers

6 Conclusion

This study found thatmost of themachines used in the quarryexceed the tolerable threshold of sound thereby having thepotential of damaging the hearing status of workers Noiselevels measured among the quarries workers studied alsoexceed the limit set by the Ghana Environmental ProtectionAgency (EPA) under the EPA Act of 1994 (Act 490) whichpermits light industrial areas It is recommended that EPAembark on regular monitoring to access noise levels andensure that companies do not emit noise greater than thetolerable limits Use of earplugs showed a protective effect ondevelopment of hearing loss Efforts to ensure access and useof earplugs by quarry workers and quarry companies couldbe beneficial in reducing the absolute prevalence of hearingimpairment especially among the elderly and long servingworkers who have been shown to be at an increased risk ofdeveloping hearing loss

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Authorsrsquo Contribution

Charles Kwame R Gyamfi designed the study CharlesKwame R Gyamfi and Frank Owusu Sekyere did baselineassessment and data collection Daniel Boateng performedthe data analysis and interpretation of findings DanielBoateng and Isaac Amankwaa wrote the first draft of thepaper which was revised and approved by all authors Allauthors approved and accepted the final paper for publica-tion

Acknowledgments

The authors express their sincere appreciation to the entirestaff of ENT units Komfo Anokye Teaching Hospital espe-cially Professor G K Amedofu Mr Osei-Bagyina DrMohammedDuah andMrs Barbara AntwiThe authors owe


much indebtedness to all those who participated in the studyand the staff and people of all the quarry companies for theirassistance in providing information towards the productionof this important document

References

[1] A H Suter ldquoThe nature and effects of noiserdquo 2011 httpwwwiloencyclopaediaorgcomponentk281-47-noisethe-nature-and-effects-of-noise

[2] M S Morris and L P Borja ldquoAir bag deployment and hearinglossrdquo American Family Physician vol 57 no 11 pp 2627ndash26281998

[3] M Concha-Barrientos D I Nelson T Driscoll et al ldquoSelectedoccupational risk factorsrdquo in Comparative Quantification ofHealth Risks Global and Regional Burden of Disease Attributableto Selected Major Risk Factors M Ezzati A Lopez A Rodgersand C Murray Eds p 1651 World Health OrganizationGeneva Switzerland 2004

[4] National Institute for Occupational Safety and Health Criteriafor a recommended standard occupational noise exposureRevised criteria 1998 httpwwwcdcgovniosh98-126html

[5] A F Ismail A Daud Z Ismail and B Abdullah ldquoNoise-induced hearing loss among quarry workers in a north-easternstate of Malaysia a study on knowledge attitude and practicerdquoOman Medical Journal vol 28 no 5 pp 331ndash336 2013

[6] C A Boateng and G K Amedofu ldquoIndustrial noise pollutionand its effects on the hearing capabilities of workers a studyfrom sawmills printing presses and cornmillsrdquoAfrican Journalof Health Sciences vol 11 no 1 2004

[7] SMulugate ldquoNoise levels in the Ethiopianwoodworking indus-triesrdquoAfricanNewsletter onOccupational Health and Safety vol2 no 1 pp 14ndash17 1992

[8] Center for Disease Control and Prevention Mining TopicHearing Loss Prevention Overview 2015 httpwwwcdcgovnioshminingtopicsHearingLossPreventionOverviewhtml

[9] A H Suter ldquoStandards and regulationsrdquo in The Noise ManualE H Berger L H Royster J D Rozster D P Driscoll and MLayne Eds American Industrial Hygiene Association FairfaxVa USA 5th edition 2000

[10] B Goelzer C H Hansen and G A Sehrndt OccupationalExposure to Noise Evaluation Prevention and Control Dort-mund for the World Health Organization (WHO) and theFederal Institute for Occupational Safety and Health (FIOSH)Berlin Germany 2001

[11] G K Amedofu ldquoHearing-impairment among workers in asurface gold mining company in Ghanardquo African Journal ofHealth Sciences vol 9 no 1-2 pp 91ndash97 2002

[12] B R Kirkwood and J A C Sterne Essential Medical StatisticsBlackwell Science Malden Mass USA 2nd edition 2003

[13] A Goodman ldquoReference levels for pure-tone audiometerrdquoASHA vol 7 pp 262ndash263 1965

[14] R Carhart ldquoAn improved method for classifying audiogramsrdquoThe Laryngoscope vol 55 pp 640ndash662 1945

[15] R Core Team A Language and Environment for StatisticalComputing R Foundation for Statistical Computing ViennaAustria 2013 httpswwwr-projectorg

[16] H Akaike ldquoA new look at the statistical model identificationrdquoIEEE Transactions on Automatic Control vol 19 pp 716ndash7231974

[17] World Health Organization Guidelines for Community Noiseedited by B Berglund T Lindvall D H SchwelaWorldHealthOrganization Geneva Switzerland 1999

[18] Environmental Protection Agency Environmental ProtectionAgency Act 1994 httpwwwiloorgdynnatlexdocsELEC-TRONIC39863101264F1742544814GHA39863pdf

[19] E R Bauer Avoiding noise overexposure at underground andsurface coal mines preparation plants and surface drillingMining Hearing Loss Prevention Workshop June 2015 httpwwwcdcgovnioshmininguserfilesworkshopshlp104-bauer-avoidingoverexposurespdf

[20] N Manna and G Basu ldquoOccupational deafness of workers in aheavy engineering industry of West Bengal India an in-depthcross-sectional studyrdquo Sudadnes Journal of Public Health vol 6no 3 2011

[21] S L Chaddha and T A Singh ldquoSurvey of noise assessment andits effect on hearing of workers in ammunition factoryrdquo IndianJournal of Industrial Medicine vol 17 no 2 pp 93ndash103 1977

[22] OHong ldquoHearing loss amongoperating engineers inAmericanconstruction industryrdquo International Archives of Occupationaland Environmental Health vol 78 no 7 pp 565ndash574 2005

[23] G K Amedofu G W Brobbey and G Ocansey ldquoThe causesand prevalence of preschool deafness inGhanardquoAfrican Journalof Health Sciences vol 4 no 1 pp 29ndash32 1997

[24] M N Fadzli Knowledge Attitude and Practice and Effectof Occupational Noise Exposure on Hearing Among SawmillWorkers in Kota Bharu Kelantan Department of CommunityMedicine USM Penang Malaysia 2005

[25] S Ferrite and V Santana ldquoJoint effects of smoking noiseexposure and age on hearing lossrdquo Occupational Medicine vol55 no 1 pp 48ndash53 2005

[26] NIOSH Noise-Induced Loss of Hearing National Institute forOccupational Safety and Health Cincinnati Ohio USA 1991

[27] H O Ahmed J H Dennis O Badran et al ldquoOccupationalnoise exposure and hearing loss of workers in two plants ineastern Saudi Arabiardquo Annals of Occupational Hygiene vol 45no 5 pp 371ndash380 2001

[28] National Institute on Deafness and Other CommunicationDisordersNoise-Induced Hearing Loss 2008 httpwwwnidcdnihgovhealthhearingpagesnoiseaspxsounds

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levels of noise In general sounds above 85 dB are consideredharmful depending on how long and how often one isexposed to them and whether you wear hearing Previousliterature shows that workers in mines quarries sawmillstextile factors printing presses and many others work withmachines that produces noisemuch higher than the toleratedlevels and therefore expose workers to potential hearing loss[5ndash7] In the large coal industry about 76 are exposedto hazardous noise [8] This causes about 25 of severehearing problems and about 80 of hearing impairment inthe workersrsquo retirement age [8]

Although the situation could be improving in developedcountries as a result of more widespread appreciation of thehazard and the institution of protective measures evidencefrom developing countries suggests that average noise lev-els are well above the occupational level recommended inmany developed nations [9 10] Increasing industrializationmight exacerbate this situation in developing countries andtherefore the need to assess the industrial noise pollutionand its impact on the hearing capabilities of workers in suchareas

In Ghana there is very little data on the effect ofnoise exposure on quarry industrial workers More so theincreasing number of patients seeking medical attention fortheir ears atHearingAssessmentCentre at theKomfoAnokyeTeaching Hospital (KATH) in Kumasi between 1995 to 1998[11] has called for the need to focus attention on noisepollution on workers in the industrial settings such as quarryindustries Furthermore no study has focused specifically onoccupational hearing loss among workers of quarry indus-tries even though the impact of noise pollution on hearingin mining company has been studied [11] This study seeks toprovide empirical evidence on the extent of noise exposureand its influence on hearing capabilities of workers in thequarry industry This would help in formulating policies andinstitute preventive measures that will help minimize the riskof occupational hearing loss among the exposed population

2 Methodology

21 Study Design and Settings This was a descriptive cross-sectional study conducted in Kwabre East District of Ashantiregion of Ghana Kwabre District carved out of the formerKwabre Sekyere District in 1988 is located almost in thecentral portion of Ashanti region It is within latitude 6∘4410158401015840north and longitude 1∘3310158401015840 to 1∘4410158401015840 west The district sharescommon boundaries with Afigya-Sekyere District to thenorth Kumasi metropolitan area to the south Ejisu-JuabenDistrict to the southeast Atwima District to the west andOffinso District to the northwestTheDistrict has a total landarea of 2468 square kilometers constituting about 101of thetotal land area of Ashanti region Kwabre District is part ofthe Greater Kumasi City region which is made up of KumasiMetropolitan Area and the surrounding Districts Accordingto 2000rsquos population and housing census the district has atotal population of about 205372 people The physiographyof the area consists of scarps formed by the extensive quarryactivities going on in the areaThemain land usage in the areacan be categorized into stone quarrying and agriculture The

quarries are mainly located near the mountains where gran-ite deposits have been detected The quarry developers leasethe land from the owners at a fee until the time the quarrywork is finishedThemain commercial purposes of quarryingare building stones and quarry dust Agricultural activities inthe area are mostly subsistence and cash crop farming

22 Study Population and Sampling The study populationwas drawn from workers of the five (5) quarry companiesnamely Northern mine quarry A Kannin mine Taysecquarry company KAS quarry company and Siemens quarrycompany Workers who have been working at the respectivequarry for more than six months were included in the studyWorkers who had previous history of hearing loss and thosenot directly involved in the quarrying process were excludedThe study comprised 400 workers from the various quarrycompanies The composition of respondents from the quarrycompanies was as follows A Kannin (120 respondents201) KAS quarry (80 respondents 134) Siemens quarry(60 respondents 10) Taysec (40 respondents 67) andNorthern mines and quarry (98 respondents 164)

The surveys were conducted from April to June 2012Based on the average number of clients per day for a specificfacility and the desired sample size a recruitment interval119896 was developed for each quarry Based on this interval the119896th worker was interviewed on each interview day until therequired sample size was reached for each quarryThe admin-istration of the study was focused mainly on the industrialnoise pollution and its impact on the hearing capabilities ofworkers The desired sample size was calculated based onKirkwood and Sterne [12] assuming a 40proportion for theevent of interest and 10 nonresponse rate

23 Data Collection Techniques and Instruments Data werecollected mainly through interviewing Participants weregiven consent form to sign and had all their concerns andquestions answered before data collection began All toolsemployed in the research were developed using standardprocedures pretested and revised to ensure their validityand reliability and research assistants were trained to ensureuniformity in the administration of questionnaires Thevarious instruments used for measuring sound levels werethe Casella sound level meter (in the recording of the noiselevels in the various companies) and pure-tone audiometer(to evaluate the hearing threshold of subjects)

231 Casella Sound Level Meter Theweighted networks in ameter are electronic circuits whose response to low frequen-cies and to very high frequencies is reduced in a specifiedmanner In general four different weightings have been stan-dardized internationally as A B C and D Network A is usedin industrial setting and this was used throughout the studyTo check for vibration shock and excessive heat a calibratorwas attached to the microphone of the meter and the readingwas then compared with the calibratorrsquos valueThemeter wasadjusted when required to bring it into calibration

232 Pure-Tone Audiometry A biologic calibration of thepure-tone audiometer was performed daily using supposedly







3 Results












119873 () 119873 ()Quarry workers


Taysec 2998 17 (43) 23 (58)Northern 2643 57 (57) 43 (43)















75

185 2 00

10

20

30

40

50

60

70

80

()



26ndash4

0(m

ild)

41ndash5

5(m

oder

ate)

56ndash7

0(m

oder

ate-

to-s

ever

e)

71ndash9

0(s

ever

e)

91+

(pro

foun

d)


Noi

se ex

posu

re

Age

15

10

5

0

20 30 40 50 60





4 Discussion











5 Limitations


6 Conclusion






Acknowledgments




References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






















3 Results












119873 () 119873 ()Quarry workers


Taysec 2998 17 (43) 23 (58)Northern 2643 57 (57) 43 (43)















75

185 2 00

10

20

30

40

50

60

70

80

()



26ndash4

0(m

ild)

41ndash5

5(m

oder

ate)

56ndash7

0(m

oder

ate-

to-s

ever

e)

71ndash9

0(s

ever

e)

91+

(pro

foun

d)


Noi

se ex

posu

re

Age

15

10

5

0

20 30 40 50 60





4 Discussion











5 Limitations


6 Conclusion






Acknowledgments




References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
























119873 () 119873 ()Quarry workers


Taysec 2998 17 (43) 23 (58)Northern 2643 57 (57) 43 (43)















75

185 2 00

10

20

30

40

50

60

70

80

()



26ndash4

0(m

ild)

41ndash5

5(m

oder

ate)

56ndash7

0(m

oder

ate-

to-s

ever

e)

71ndash9

0(s

ever

e)

91+

(pro

foun

d)


Noi

se ex

posu

re

Age

15

10

5

0

20 30 40 50 60





4 Discussion











5 Limitations


6 Conclusion






Acknowledgments




References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















75

185 2 00

10

20

30

40

50

60

70

80

()



26ndash4

0(m

ild)

41ndash5

5(m

oder

ate)

56ndash7

0(m

oder

ate-

to-s

ever

e)

71ndash9

0(s

ever

e)

91+

(pro

foun

d)


Noi

se ex

posu

re

Age

15

10

5

0

20 30 40 50 60





4 Discussion











5 Limitations


6 Conclusion






Acknowledgments




References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






















5 Limitations


6 Conclusion






Acknowledgments




References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















References


































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of





















of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















research article noise exposure and hearing capabilities

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