The nature of work that is commonly done in sawmills, together with the quantity of woods being worked on generate a lot of noise to the working environments. Noise is hazardous to human health as it can cause increased blood pressure, sleep deprivation and other physiological as well as psychological effects on the workers. The aim of this study was to assess the noise exposure level of sawmill workers to evaluate their safety at work. Three sawmills, all located in Ibadan, Oyo State, South-Western Nigeria were selected for study. Noise level measurements for planning, circular and drilling machines used in the three sawmills were determined using a precision sound pressure tester measurement. The fraction of exposure, and daily personal exposure levels for each of the machines were obtained. Also, questionnaires were administered to obtain subjective responses from the workers on their demographic data, their knowledge about sawmill noise and impact, as well as perception of noise on the workers. SPSS version 20 was used for data entry and analysis.
Bodija, Olorunsogo and Olunde sawmills were selected for study in the region. 94.0dB was obtained on the LCD display of the noise level meter after calibration. Maximum values (100.3dB, 986Db, …, 3.46dB) and minimum values (91.5dB, 96.6dB, …, 81.1dB) were obtained for each of the three sawmills under study. The readings: 5.57, 24.88 and 1.57 were obtained as the fraction of exposure for the circular, planning and drilling machines respectively. Daily personal exposure levels for an 8 hours operation time for the machines were 98dB(A) for the circular machine, 104dB(A) for the planning machine and 92dB(A)for the drilling machine. All these values were found to be greater than the maximum permissible limits specified by OSHA and WHO. From the questionnaires administered, it was discovered that 78.7% of workers have their performance reduced by the noise exposure while 74.5% complain of headaches when the machines are in operation and 51.1% have symptoms of NIHL. Noise exposure for workers in the sawmill is higher than the permissible noise limit and therefore is hazardous to the health of both the workers therein and the people living around the environment. This negatively affects the performance and productivity of the workers as well as the comfortability of nearby residents.
Keywords : Health, Noise exposure, Noise level, Noise measurement, Sawmill, Sound, Woods.