[Occupational noise exposure evaluation in drivers of bus transportation of Tehran City]

ABSTRACT

Noise in large cities is considered by the World Health Organization to be the third most hazardous type of pollution. Buses are an interesting object of study in the theme of noise pollution. They are at the same time a source of urban environmental [traffic] noise and occupational noise exposure source for drivers. The object of this study is Occupational noise exposure evaluation in drivers of bus transportation of Tehran city. Noise levels in 90 buses were sampled in three separate sub-sample including [1]30 Ikaroos buses [2]30 Man buses [3]30 Shahab buses, which were selected by simple random sampling. Noise exposure level was normalized to a nominal 8-h working day [LEX, 8h]. Simultaneous Octave Frequency Analysis were measured and sound intensity level [SIL] for bus drivers were calculated. Results, which are obtained from separate buses were compared together and too with standard levels. the normalized noise exposure levels [LEX, 8h] in Ikaroos bus drivers[82dB A] were higher than that of in Man bus drivers [77/6dB A] and this Values were higher than that of in Shahab bus drivers[75dB A].SIL values for Ikaroos bus drivers were higher than other that of other bus drivers. Results obtained of Frequency Analysis showed that age of buses in mid frequencies ws a meaningful on noise increase. Results showed that type and age of buses were effective factors in drivers' noise exposure levels [LEX, 8h], which was consistent with previous studies in this field