Monthly variation in night time noise levels at residential areas of Asansol city (India).

Intense vehicular movement and industrial activities are the major noise producing sources in the Asansol city. Ambient night time noise levels were monitored in ten residential areas from August 2002 to July 2003, to study the existing quality of noise and their impact in the local community. Based on the monitored noise levels in the area, traffic-social survey was also conducted. About 39% of individuals surveyed were highly annoyed with noise pollution from different origins. The study revealed that night time noise levels (10.00 pm - 6.00 am) in all the locations exceeded the limit prescribed by Central Pollution Control Board. The day time noise level was much higher at all locations in respect of the night time noise level. The Day-Night equivalent noise level (Ldn) was determined and ranged between 67.16 dB(A) and 89.44 dB(A). The percentile noise level (L90) exceeded the CPCB standard in all cases and varied from 72.36 dB(A) to 102.45 dB(A). Based on the results of the study, it can be concluded that the local community is exposed to high noise environment.