OBJECTIVE: To determine the level of noise produced by the engine and siren of a mobile support unit, and to check its influence on the health of the workers. METHODS: A survey was performed to measure the noise produced by the engine and siren of a Mercedes-Benz, a Sprinter 313 CDI, and a 3-door, Diesel, 2008 support unit. The following was measured: noise while the engine was running 1000 rpm, 2000rpm, and 3000 rpm and noise while the siren was on and the ambulance stopped. RESULTS: The workers were simultaneously exposed to the noise produced by the operations of the engine and siren. When the ambulance stopped and was idle (SPL = 61.5 dB [A]) with the siren running (SPL = 74.9 dB [A]), the worker is exposed to a sound pressure level of 75.1 dB (A); if the engine is running at 3000 rpm (SPL = 70.8 dB [a]) this value would be 76.3 dB (a). Traffic noise, which in the main access roads to Belo Horizonte has an average of 73 dB (A), should also be considered, and this will cause more harm to the workers' health triggering a typical hearing loss and interfering with the quality of life. CONCLUSION: The team of professionals who work with ambulances are exposed to high noise levels. According to the NR15, the maximum tolerated exposure is 85 dB (A) for 8 hours daily with the noise being continuous or intermittent. However, most workers have a journey time of 12 hours, increasing the risk of development of auditory and extra-auditory problems.