An Assessment of Occupational Noise Levels in a Plastic Manufacturing Industry in Zimbabwe

Abstract

The aim of the study was to assess occupational noise levels in a plastic manufacturing industry in Zimbabwe between April 2014 and July 2014. The research followed an experimental design set up. Three sites were selected (1, 2 and 3) and each site had three sampling points randomly selected where the measurements were done. One out of two workers per site (three sites in total) was chosen and occupational noise levels were measured using a sound level meter which was calibrated. Measurements were done at hourly intervals for 8 hours. These were done for five days a week during the three weeks per month for a total period of three months. In order to determine the Time Weighted Average (TWA), a formula was used for the calculations. Results showed that the average noise levels ranged from 89–96 dBA among the study sites. Results from ANOVA showed that there was no significant difference in the TWAs among the sites (F=1.67; df=2 and 126; P=.19), among the workers (F=.17; df=2 and 126; P=.54) and the interaction of site and worker (F=1.67; df=4 and 126; P=.16). The one sample t-test for comparison of the 8hr TWA noise levels with the national and International standards showed that the mean TWA was significantly higher than the Zimbabwean standard by a mean difference of 3 dBA (t=15,79; df= 134; P<.0001). The mean TWA was also significantly higher than the International standard by 8 dBA (t=41.53; df= 134; P<.0001). The present findings suggest that the noise levels in the plastic manufacturing industry under study were high in all the three sites. Workers are exposed to noise levels which are above the international legislated occupational level.