Sound above what level (in decibels) is considered hazardous noise pollution?

The answer is D) 80 dB. Sound above roughly 80 dB is treated as hazardous noise pollution in standard textbook and exam framing, because prolonged exposure at that level starts to strain hearing and cause stress and sleep disturbance.

• A) 30 dB is about the level of a quiet library or whisper, which is far below any harmful threshold.
• B) 40 dB is a quiet residential night-time environment, comfortable and not hazardous.
• C) 60 dB is ordinary conversation. It can be annoying in a quiet zone, but it is not treated as hazardous.

The concept sits under the Environment (Protection) Act, 1986 and the Noise Pollution (Regulation and Control) Rules, 2000, which fix zone-wise ambient limits. Do not confuse those permissible zone limits, such as 55 dB for residential day-time, with the hazard threshold. For Mains, link this to urban health and the enforcement gap in the 2000 Rules.

Trap: aspirants often pick 85 dB from occupational safety norms (the 8-hour exposure limit used by WHO and OSHA) or pick a zone limit like 55 or 75 dB. Read whether the question asks for a hazard level or a regulatory limit.