Occupational noise in urban buses

The noise level environment for Brazilian urban bus drivers (city of Curitiba) was examined. Noise levels were measured in 3 types of buses: (1) bi-articulated, (2) speedy, and (3) feeder, 20 buses of each type. Bi-articulated buses are formed by three cars and two hinges, and operate in exclusive lanes, where cars are not allowed. They stop at specific stations intended for rapid loading and unloading of passengers. Speedy buses operate in regular streets across the city, but they stop at fewer stations than other buses. Feeder buses operate normally in the whole city, along regular streets and bus stops. The evaluation of noise levels in the workplace of bus drivers (that is, inside buses) was performed according to ISO 1999 (Determination of occupational noise exposure), and the brazilian Standards NHO-01 (Occupational Health Standard), and NR 17 (Standard for Ergonomics). In 56 out of the 60 buses examined, the normalized noise exposure levels LEX,8h were below 82 dB(A). The quality of the workplace was thus considered as “acceptable”. The four buses with measured noise levels above 82 dB(A) demand the adoption of preventive and corrective measures (NHO-01) aiming at reducing noise emission levels. These buses are older and have the engine located in the front. On the other hand, when NR-17 is used as a reference for the evaluation of the noise quality in the workplace of the bus drivers, all buses were considered uncomfortable, with LEX,8h>65 dB(A). Year of manufacture and location of the engine are two factors that highly contribute to the level of noise reaching the driver. These considerations are of relevance, as the placement of the bus engine can be decided at the time of projecting the bus.