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Med. Pr. 2001;52(4)

Risk of noise-induced hearing loss in farm tractor operators

Ryzyko utraty słuchu wśród operatorów ciągników rolniczych spowodowane hałasem

L. Solecki

Abstract

Studies of noise at work site of tractor operators showed that this parameter exceeds allowable values. In order to evaluate the risk of hearing loss in this occupational group, noise-induced permanent threshold shift (NIPTS) values were determined. This parameter is a function of the audiometric frequency, duration of occupational exposure and noise exposure level (L_EX,8h). The procedure recommended by ISO-1999/1990 was used for calculations. The study covered two groups of operators:operators of ZM "Ursus" medium-power tractors (noise exposure level:L_EX,8h = 96.6 dB) and operators of high-power tractors of the same manufacture (L_EX,8h = 89.6 dB). The risk of hearing impairment was determined for the group of men aged 50 years, occupationally exposed to noise for a period of 30 years. The calculation was based on the mean value of expected hearing loss for three selected audiometric frequencies: 1000; 2000; and 4000 Hz. The study showed that the average (median; N_0,50 )expected hearing loss,excluding that associated with age, after 30 years of employment was 15 dB for operators of medium-power farm tractors, and 6 dB for operators of high-power tractors. The risk of hearing impairment due to occupational exposure to noise (exceeding the maximum allowable hearing loss of 27 dB; according to ISO-1999/1990) that may cause an acoustic trauma was 37.9% for medium-power tractors and 13.0% for high-power tractors. The results of the study show that noise at workplaces of farm tractor operators creates a high risk of hearing impairment. Med Pr 2001; 54; 4; 265ś270.

Key words

risk, age, noise, hearing loss, threshold shift, noise exposure level