Abstract

Introduction: Annually, there are an estimated 271 million people who suffer harm due to factors in their workplace throughout the world owing to poor safety practices at their workplaces, thereby affecting efficient and effective productivity. An estimated economic loss of 4% of the world’s Gross National Product is caused by harm suffered in the workplace, affecting the workers and their families. Worldwide, 16% of the disabling hearing loss in adults (over 4 million Disability Adjusted Life Years) is attributed to occupational noise. Noise is one of the most pervasive pollutants and occupational hazards in the world today, and can be dangerous to health when it is too loud and/or when it goes on for a reasonable length of time. The most scientifically established health effect of noise is noise-induced hearing loss. This study was carried out in order to determine and compare the prevalence, knowledge, perception of hearing, attitude, safety practices and the
associated factors related to hearing loss among public-sector airport workers and workers in a non-noisy workplace in Lagos.
Materials and methods: This study was a comparative cross sectional study conducted from April to June 2013. A multistage sampling method was used to select 250 airport workers at the Muritala Mohammed Airport, Lagos and 252 workers at the Lagos State Secretariat, Alausa, Ikeja. Trained interviewers administered adapted and pre-tested questionnaires, experienced audiologists carried out audiometry on respondents and respondents’ workplace sound levels were also measured. Data were analysed using Epi-Info 2008 version 3.5.1 and Microsoft Excel software. Results were presented in frequency tables. Chi- square test was used to assess the associations between categorical variables and t-test was used to compare the quantitative variables. Multiple logistic regression was used to compare variables and identify the predictors of hearing loss among among public-sector airport workers and workers in a non-noisy workplace in Lagos. The level of significance was set at p<0.05.
Results: The ages of the workers in both groups were comparable, about half of the respondents were males and half female, and most had tertiary education. The number of years of service and the number of working days per week varied comparably. The level of knowledge of the effects of noise in the workplace was good among 58.8% of the airport workers and 38.5% of the secretariat workers. Over 70% of the respondents in both groups perceived their hearing to be optimal whether they experienced hearing loss or not. Most (60.7%) of the airport workers had a negative attitude to the use of hearing protective equipment. Only 21.6% of airport worker used hearing protective equipment. A small proportion (11.2%) of the airport workers had ever had some kind of training on workplace
noise and the proper use of hearing protective equipment. The prevalence of hearing loss amongst airport workers was 40% compared to 7.1% among secretariat workers. There was a statistically significant association between self-reported hearing loss and clinically proven hearing loss. The ages of workers at the airport, gender, workplace noise levels, years of service at work, alcohol intake and the presence of a chronic disease such as hypertension among the airport workers were found to be significantly associated with hearing loss. Multiple logistic regression identified workplace sound levels (aOR = 14.06, CI 1.65 – 26.0), self-reported hearing loss (aOR = 9.80, CI 3.70 – 26.05), awareness of the workplace as being noisy (aOR = 0.29, CI 0.11 – 0.80), work location (aOR = 2.51, CI 1.41 4.40), presence of a chronic disease (aOR=4.36, CI 1.91 – 9.95), alcohol use (aOR=2.26, CI 1.27 – 4.02) and for airport workers only, department at work (aOR=3.95, CI 1.41 – 11.01(operations department), aOR=3.94, CI 1.37–11.32(engineering department)) as significant predictors of hearing loss among the respondents.
Conclusion and recommendation: The noise levels at the airport exceed the allowable 85dB. Over half of the airport workers had a good level of knowledge of the effects of workplace noise compared with 38.5% of secretariat workers. The airport workers were found to be about 9 times more likely to have hearing loss than the secretariat workers. The predictors of hearing loss in this study were identified as high workplace sound levels, self-reported hearing loss, awareness of the workplace as being noisy, if suffering from a chronic disease, alcohol use, working at the airport and working particularly in the operations department at the airport.
From this study it is recommended that there should be regular training on the hazards of exposure to loud noise, the effect of workplace noise, the use of hearing protection and on
general workplace safety. The provision of effective and proper protective devices suited to the work at the airport and adopting a Hearing Conservation Program for all the workers working at noise levels over 85dB is paramount in preventing hearing loss, which is irreversible.