Impact of intense field burning episode on aerosol mass loading and its possible health implications in rural area of eastern central India

Abstract

Size-segregated aerosol samples were collected from the rural area of eastern central India throughout the intermittent rice straw burning campaign during May and June in 2013. We found higher concentrations of particulate matters (PMs) during field burning events. The average concentrations of PM10 (RSPM, Dp ≤ 10 μm), PM2.5–10 (coarse, 2.5 μm < Dp < 10 μm), PM2.5 (fine, Dp ≤ 2.5 μm), and PM1 (submicron, Dp ≤ 1 μm) were found to be 329 ± 25.6, 108 ± 5.02, 221 ± 25.1, and 90.4 ± 18.2 μg/m3, respectively. The concentrations of PM10, PM2.5, and PM1 during burning period were approximately two times higher than those of pre-burning and post-burning periods. The percentage contribution of fine particles to the total PM10 during burning period was found to be approximately 70 % whereas it was limited to approximately 51 and 50 % for pre-burning and post-burning periods, respectively. Significant correlation was found between PM10, PM2.5–10, PM2.5, and PM1 during burning period due to continued emission of aerosol from rice straw burning. Surprisingly, we found good correlations between coarse, fine, and submicron particles during burning period that are mainly due to accumulation of small particles and/or their adsorption from gas phase to larger particles. The contribution of fine aerosols is higher as compared to coarse aerosols to the total PM10 mass. PM10 and PM2.5 concentrations during the study period were 100 % exceeded from the prescribed national air quality standard of Central Pollution Control Board (CPCB), India. According to the mass size distribution, the major peak was present in fine size fraction during burning event whereas for pre- and post-burning periods, it was present in coarse size fractions. During burning period, approximately 70 % of particulate matters were distributed in sizes less than 2.5 μm. The mass median aerodynamic diameter was shifted to a lower size range (1.91 μm) for total aerosol particle sizes during burning period as compared to pre- and post-burning periods due to high emission of fine particle. Deterioration of air quality was more prominent during burning period as compared to that during pre- and post-burning periods. The mass concentration of particles, which are able to get deposited in respirable airways and lungs, was found to be higher during burning period.