Evaluation of noise pollution and the efficiency of workers personal protective equipment in a plastic manufacturing factory in Birjand city

Background:Disturbing noise in a workplace is one of the main harmful occupational factors which has irreparable consequences for the health of workers. Technical evaluation of this problem opens the way to take precautionary measures in order to protect the health of workers, who constitute the main capital of each country. This study was conducted to evaluate noise pollution and the efficiency of personal protective equipment in the workers of a plastic manufacturing factory in Birjand city. Methods:In this descriptive cross-sectional study, noise measurements were performed through stationing method using the sound-sensor analyzer, TES 1358A model, in 27 stations, and indicators of exposure level for workers and interference level in conversation were calculated using relevant relations. Also, the efficiency of workers’ protective earmuffs was investigated by octave-band method. Finally, the data were analyzed in SPSS software using t-test. The significant level was set at P ≤ 0.05. Results:In the production hall, the mean and the standard deviation of the noise intensity level was 83.9±3.03 dB and it was 88±3.06 dB in the mill, showing that 47.6% of the stations in the production hall and 83.3% of the stations in the mill had a noise intensity level higher than the limit. The mean and the standard deviation of the workers exposure level was 85.7±2.8 dB, which in 71.43% of cases, it was more than the limit. The efficiency of the workers’ protective earmuffs was acceptable at frequencies of 1000, 2000, 4000 and 8000 Hz with a significant decrease in the noise intensity level at these frequencies (P=0.001). However, their efficiency was not acceptable at 250 and 500 Hz. The interference level in conversation was 61.3 dB in the production line and 85.5 dB in the mill. Conclusions:In some sections of the production hall and the milling hall of the studied factory, the noise intensity level and the 8-hour exposure level of the workers are higher than occupational limits, which indicates that noise pollution is one of the problems of the factory that needs to be addressed via controlling methods. Also, the examination of the efficiency of the workers’ protective earmuffs indicates that these earmuffs are not efficient at frequencies of 250 and 500 Hz, and based on the results of the factory’s noise measurement, the workers should be provided with appropriate protective earmuffs.