WORK ENVIRONMENT NOISE LEVELS AND AUDITORY STATUS OF GENERATOR USERS IN AGBOWO AND AJIBODE AREAS OF IBADAN, NIGERIA

Abstract

The increasing use of electric generators in small scale businesses is predicated on the erratic and inadequate power supply in Nigeria. Electric generators produce noise at levels capable of inducing hearing impairment. Hitherto, few studies have assessed the auditory status of generator users in Nigeria. This study was designed to compare the work environment noise levels and auditory status of generator users in two areas where generators are used in Ibadan. A comparative cross sectional study was conducted in Agbowo (high generator use) and Ajibode (low generator use) areas of Ibadan. Noise levels of work environment were measured using calibrated AEMC sound meter. Measurements were made before business activity commenced (6am-8am), at the peak of business activity (11am-1pm) and at the close of business activity (4pm-6pm) for a period of 12weeks. Generator characteristics were documented with a checklist. All 515 generator users in both communities (Agbowo: 304, Ajibode: 211) were surveyed. Information on socio-demographic characteristics and pattern of generator use were obtained with a pretested interviewer administered questionnaire. One hundred and twenty two and 84 users who reported daily generator use in Agbowo and Ajibode respectively were recruited for audiologic evaluation. Audiometric measurements were done with calibrated Maico MA27 audiometer. Hearing impairment was defined as audiologic values of >50dB in both ears while excessive noise levels in work environment was defined as > 70dB(A) in accordance with WHO standards. Data were analyzed using descriptive statistics, Chi-square test and Logistic regression. The average noise level around the work environment in Agbowo (78.5±3.9dB(A)) significantly exceeded the WHO standard [65-70dB(A)] compared with Ajibode (59.7±4.4dB(A)). The maximum noise level obtained was during the peak activity period of 11am-1pm; Agbowo: 84.4±8.74dB(A) versus Ajibode: 69.9±4.65dB(A) (p<0.05). The mean generator noise levels in Agbowo and Ajibode were 100.5±7.5dB(A) and 91.2±4.86dB(A) respectively (p<0.05). The proportion of diesel engines in Agbowo (65.0%) exceeded those in Ajibode (10.0%). The mean age of generator users in Agbowo and Ajibode were 25.4±5.4 years and 24.8±5.8 years respectively. The average daily generator use were [Agbowo: 5.5±1.7 hours/day and Ajibode: 2.1±1.1 hours/day] respectively (p<0.05). The mean distance of generator to users was significantly lower in Agbowo (1.9±1.5m) than in Ajibode (5.6±4.1m). More respondents in Agbowo (60.0%) compared with those in Ajibode (19.0%) placed their generators indoors during business activity (p<0.05). The audiometric assessment revealed pure tone average of 59.6±11.7 dB and 44.5±14.7 dB for generator users in Agbowo and Ajibode respectively (p<0.05). The proportion of those with hearing impairment in Agbowo and Ajibode were 75.6% and 34.5% respectively (p<0.05). Hearing impairment was higher among generator users in Agbowo compared with their counterparts in Ajibode (OR: 5.9, 95%CI: 3.2-10.8). Noise levels in Agbowo area exceeded the standard for work environment and the burden of hearing impairment is high in the two areas. The use of sound-proof generators and ear plugs are recommended to ameliorate the potential effect of generator noise on hearing.