[Acoustic contamination in urgent medical transportation by road]

To determine levels of exposure to noise during urgent medical transportation by road and to describe the perception of hearing function impairment in workers and the use of hearing protection devices.

An observational study was performed in Bizkaia (Spain). The instantaneous maximum noise levels (L(peak)) and its continuous equivalents (L(eq)) were recorded through sonometric dosimetries, measured in a "sample ambulance" of the emergency network. In parallel, a survey was conducted on a representative sample of 127 workers in which self-reported hearing loss and associated factors were explored, in addition to other issues of concern from the perspective of prevention of occupational hazards.

L(peak) oscillating between 80 and 109 dBA were recorded depending on the location. The average Leq levels measured over 10 emergency calls, from activation until arrival at the incident and during transport to the hospital, were of 79.5 dBA and 74.3 dBA (p <0.001) respectively. Thirty-six point two percent of the surveyed workers spoke of hearing impairment in recent years. The independent variables associated with increased risk were: age over 45 years, professional seniority over 15 years and male gender. The strategies used to mitigate the siren's noise during the emergency were closing the windows of the ambulance and using the dimmer at night.

The values of the dosimetries do not exceed the critical values provided, but there is a high prevalence of hearing-impaired problems reported by the workers. Emphasis should be placed on the adoption of strategies to reduce noise and its effects on the ambulance service.