Calcutta metro: is it safe from noise pollution hazards?

A modest assessment of noise was made in Calcutta Metro, India's first ever underground tube rail system, to examine if the range of noise levels present could endanger the hearing sensitivity of workers for the Metro. Sound measuring instruments of a sound level meter, an octave band analyzer, and a sound level calibrator were used for measuring the sound pressure levels in platforms of three stations: Esplanade, Kalighat and Tollygunge. The results indicated that the averaged A-weighted SPLs in these stations were in the range of 84-87 dBA. In the coaches of the moving train the Leq values ranged 92-99 dBA and LNP 105-117 dBA, all exceeding the safe limit of day time noise exposure of 55 dBA and 85 dBA of ACGIH. The SPLs at 4,000 Hz in the coaches were also in excess of safe exposure limit of 79 dB. The findings thus posed a potential threat to the workers.