Noise exposure during alpine helicopter rescue operations.

OBJECTIVES: We estimated the noise exposure of crews working in alpine helicopter rescue systems. METHODS: Noise levels of the the helicopters used (Alouette III, Alouette II 'Lama', Ecureuil and BK 117) were measured with a device according to class 2 DIN IEC 651. These data were combined with the flight data of the personnel to evaluate the equivalent noise level according to DIN 45645-2. RESULTS AND CONCLUSIONS: While the risk to patients should be limited to temporary threshold shifts the crew members are regularly exposed to equivalent noise levels of >85 dB(A) and, therefore, are at risk of permanent threshold shifts. Consequences for crew fitness to fly and for noise prevention (crew and patients) are discussed.