1. Ambient Air Quality. Data from continuous monitoring of air quality reveals that while suspended
particulate matter levels still far exceed stipulated standards, there is a significant downward
trend.
Noise levels in Delhi exceed permissible levels in all areas except industrial areas, according to
a study by the Delhi Pollution Control Committee. Since noise is measured on a logarithmic scale, an
increase of every 3-5 dBA has twice the effect on humans. Diesel generating sets and vehicles, particularly
auto-rickshaws, have been identified as major sources of noise pollution in Delhi.
2. Air Pollution. The 1991 report by the National Environmental Engineering Research Institute
(NEERI), Nagpur documents the amount of pollution that is contributed by different sectors in Delhi: