SEASONAL VARIABILITY OF TSPM, PM10 AND PM2.5 IN AMBIENT AIR AT AN URBAN INDUSTRIAL AREA IN EASTERN CENTRAL PART OF INDIA

Total Suspended Particulate Matter (TSPM), PM10 and PM2.5 were simultaneously monitored during the year 2015 at Raipur, an industrial-urban location in easterncentral part of India. Sampling was carried out using high volume sampler, respirable dust sampler (PM10) and fine particulate (PM2.5) samplers. Samplers were operated for 24 hours (8-hour cycles for TSPM and PM10) on several days covering the five main seasons. Daily TSPM, PM10 and PM2.5 average concentrations varied between, 44.50 and 566.22 (mean: 277.85±170.81 µg/m3); 37.30 and 344.57 (mean: 162.69±71.74 µg/m3); 18.92 and 229.77 (mean: 108.31±40.41 µg/m3); respectively. TSPM, PM10 and PM2.5 mass concentrations showed distinct seasonal cycle; TSPM – (Winter; 419.49 µg/m3 ) > (Autumn; 366.93 µg/m3) > (Monsoon; 66.92 µg/m3); PM10 – (Winter ; 237.10 µg/m3) > (Spring; 185.82 µg/m3) > (Autumn; 172.52 µg/m3) > (Summer; 142.93 µg/m3) > (Monsoon; 58.24 µg/m3) and PM2.5 – (Autumn; 132.15 µg/m3) > (Winter; 119.56 µg/m3) > (Spring; 115.98 µg/m3) > (Summer; 89.87 µg/m3) > (Monsoon; 64.71 µg/m3). This seasonal variation may be due to the prevailing meteorological conditions, anthropogenic activities, biomass burning and autumn season festival events. Higher PM2.5/PM10 ratio during monsoon season, may be due to greater washout of the coarser particles compared to the finer. A clear inverse relationship between PM2.5 and wind speed (r = -0.24) and PM10 and wind speed (r = -0.08) was found. Above findings will be helpful in; understanding seasonal variations in size distribution of particulates, source apportionment study, mitigation and air pollution control strategy.