Distribution of PM2.5 and PM10-2.5 in PM10 Fraction in Ambient Air Due to Vehicular Pollution in Kolkata Megacity

Abstract

This research paper aims at establishing baseline PM(10) and PM(2.5) concentration levels, which could be effectively used to develop and upgrade the standards in air pollution in developing countries. The relative contribution of fine fractions (PM(2.5)) and coarser fractions (PM(10-2.5)) to PM(10) fractions were investigates in a megacity which is overcrowded and congested due to lack of road network and deteriorated air quality because of vehicular pollution. The present study was carried out during the winter of 2002. The average 24h PM(10) concentration was 304 microg/m(3), which is 3 times more than the Indian National Ambient Air Quality Standards (NAAQS) and higher PM(10) concentration was due to fine fraction (PM(2.5)) released by vehicular exhaust. The 24h average PM(2.5) concentration was found 179 microg/m(3), which is exceeded USEPA and EU standards of 65 and 50 microg/m(3) respectively for the winter. India does not have any PM(2.5) standards. The 24 h average PM(10-2.5) concentrations were found 126 microg/m(3). The PM(2.5) constituted more than 59% of PM(10) and whereas PM(10)-PM(2.5) fractions constituted 41% of PM(10). The correlation between PM(10) and PM(2.5) was found higher as PM(2.5) comprised major proportion of PM(10) fractions contributed by vehicular emissions.