A survey on individual noise exposures in a noisy factory.

Abstract

In order to estimate the individual noise exposure in a factory using several types of hand tools, it is unsatisfactory to measure the sound level emitted from the tools or to simply measure the sound level at various points in the work space. The authors tried to compare the results of a personal noise dosimeter, Rion Co. Ltd., Japan (type : NB-02A), with the results of stationary sound level meters, 10 channel noise dosimeters (Rion, type NA-76) and a digital sound level meter (Rion, type NA-76). Two workshops, welding and repairing by sixteen and fourteen workers respectively, in an airplane repair factory, were surveyed.The personal noise dosimeters were set to measure the time duration exposed equal to or more than 80 dB (A) and were carried individually in the breast pocket of each worker from 10 a.m. to 4 p.m. in the same day. The exposure time data were also given from stationary measurement points.Sound levels of all the hand tools, for example, hand hammer, air grinder, rivett gun, air drill etc., were more than 85 dB (A) at the point of one meter (1 m) apart from the tools. So the sound from the tools will be accumulated from the time when the workers switched them on. The workers used the tools individually, according to the various work processes. Stationary noise measurements showed that 75 dB (A) was L50 in the welding shop, and the duration exposed equal to or more than 80 dB (A) was 109 and 97 minutes at two points. Measurements by the personal noise dosimeters varied from 103 to 221 minutes for twelve workers in the welding shop who used mainly hand tools. A longer term survey on individual noise exposures will give more precise data on the relationship between the noise dose and the noise induced permanent threshold shift of workers.