The major impacts have been observed through the implementation of emission norms and fuel
quality specifications effective from 1996, as also phasing out of 15-year-old commercial vehicles and
leaded petrol in the year 1998 and phasing out of 8-year-old commercial vehicles and 15-year-old two
wheelers from 2000 onwards. The ambient air quality as monitored by CPCB during 1999 shows reduction
in levels of various pollutants in ambient air as compared to previous year. The reducing trend was
observed with respect to Carbon Monoxide, nitrogen dioxide, and lead in residential areas.