Abstract
The National Institute for Occupational Safety and Health (NIOSH) was requested to conduct a health hazard evaluation (HHE) at a large metropolitan fire department. The request concerned the hearing levels and noise exposures of fire fighters who were assigned to two fire stations serving the international airport. There was concern that these fire fighters were at a greater risk of accruing hearing loss than fire fighters located at other fire stations because of the addition of aircraft noise to their occupational noise exposures. The city also requested that NIOSH investigate other fire stations, not influenced by the airport, for noise exposures and hearing ability among a larger population of the fire fighters. NIOSH investigators conducted noise surveys at five fire stations and examined the hearing ability of 197 fire fighters. The noise surveys consisted of personal noise dosimetry on fire fighters assigned to the fire station for the entire 24-hr tour of duty over 2 consecutive days at each of the five stations. A NIOSH investigator accompanied the fire fighters on their vehicle to log response times and activities. The audiometric examinations were pure-tone, air conduction tests administered according to the Occupational Safety and Health Administration's (OSHA's) hearing conservation amendment. The noise dosimetry results revealed time-weighted averages (TWAs) that ranged from 60 to 82 dBA. However, the levels encountered during Code 3 responses (warning lights, sirens, and air horns) reached 109 dBA for a 1-min time period. The audiometric results showed that the average fire fighter exhibited a characteristic noise-induced permanent threshold shift. This hearing loss was statistically related to the amount of time that the fire fighter had been on the job with decreasing hearing ability as a function of years of service.