Avenue plantations in Delhi and their efficacy in mitigating air pollution

Abstract

ABSTRACTTo develop effective vegetation strips for filtering out point source air pollutants, several characteristics of vegetation strips and concentrations of 6 air pollutants (PM10, PM2.5, SO2, NOX, ozone, benzene) at five sites in Delhi were studied. Four air pollutants were within the prescribed limits; whereas the concentration of PM10 (80.27−710 μg/m3) was 3-4 times while PM2.5 (27.34−327.11 μg/m3) was 2-3 times higher than the standard limits notified by the Ministry of Environment, Forest and Climate Change, Government of India in 2009. Anand Vihar (AV) was the most polluted site whereas the Mandir Marg (MM) the least polluted. Species composition of the vegetation strips and their abundance, canopy type, and size of the leaf determined the efficacy as a filter for air pollutants. The abundance of broadleaved species such as Ficus religiosa, Alstonia scholaris and Polyalthia longifolia showed negative, statistically significant (p < 0.01) relationships with all the air pollutants analysed suggesting an abundance of broadleaved trees are effective in the filtration of air pollutants. The abundance of microphyllous trees such as Prosopis juliflora were the least effective filters. Ficus religiosa was the most effective tree species with respect to filtering air pollutants and particulate matter.