Changes in hearing acuity in ambulance personnel

To determine whether emergency medical technicians (EMTs) and paramedics suffer excessive hearing loss as a result of occupational noise exposure. A secondary objective was to determine noise levels in a modern ambulance.

This retrospective study reviewed audiograms for EMTs and paramedics currently employed by the Louisville Emergency Medical Services. The age-adjusted threshold shift was calculated for the right and left ears at 1,000, 2,000, and 4,000 Hz in 81 of these individuals. Seventy-four of the subjects also had measurements that allowed similar calculations at 3,000 Hz in both ears. The age-adjusted threshold shift was then correlated with the elapsed time. Second, noise levels were measured inside an ambulance at several times during an eight-hour shift.

The correlation coefficient of age-adjusted threshold shifts and elapsed time was greatest at 2,000 Hz in the left ear but was still not significant at -0.2692. The noise levels in the ambulance ranged from 58 dBA in the patient compartment while stationary to 84 dBA in the forward cab with the windows down and the siren in use.

There was no significant correlation between the number of months elapsed between audiograms and the age-adjusted threshold shift at any frequency in either ear. There appears to be no excessive loss of hearing acuity in ambulance personnel. The noise levels in the study ambulance stayed well below the Occupational Safety and Health Administration (OSHA) guidelines.