Impacts of the steps taken in Delhi: All regulatory pollutants show a decreasing trend in concentrations in Delhi. CO decreased to 3069 ug/m3 in 2000-2001 from 5450 ug/m3 in 1998. NO2 decreased from 75 ug/m3 in 1996 to 59 ug/m3 in 2000. Lead which is harmful especially for children, decreased remarkably due to phasing out of lead from gasoline. Another critical pollutant RSPM also shows a decreasing trend in Delhi.