Air pollution from biomass burning in India

Abstract

Air Pollution is the most difficult challenge India is facing today and anthropogenic biomass burning (ABB) is one of the major and least understood sources leading to serious health and climate implications by affecting air quality, visibility, atmospheric chemistry, the Earth’s radiation budget, and biogeochemical cycling. Scientific understanding on the composition, chemistry, and regional dynamics of BB emissions is still limited constraining the implementation of appropriate research and policy interventions. The broad categories, associated complex emissions and spatio-temporal variations of ABB in India are discussed here. Major types of ABB prevalent year-round all over India include BB for cooking, heating purpose and open waste burning. Moreover, crop residue burning (CRB) in Indo-Gangetic Plain (IGP) during pre (April-May) and post-monsoon (October-November) seasons; CRB in South-India during January-February; forest fires in Central India and slash & burn agriculture in North-East India during March-May are the other dominant sources active during specific months and regions. Over the IGP, CRB along with other episodic ABB events and stagnant meteorology result in severe air quality and poor visibility (< ~300 m) with reported daily mean PM2.5 concentration shooting upto 15 times higher than Central Pollution Control Board standards. When compared with wheat residue burning, higher fire counts and emissions are reported during paddy residue burning events. During winters, BB contribution to 37% of aerosol oxidative potential in Delhi indicates its health implications. Meta-analysis of data obtained from representative source apportionment studies on PM10 shows >24% BB contribution in Assam, Ahmedabad, Kanpur, and Visakhapatnam; 20-24% in Patiala and Kolkata; 10-14% in Delhi. In PM2.5, BB contribution of >24% in Ahmedabad and Agra; 15-19% in Delhi, Mumbai, and Kolkata is reported while in PM1, BB contributed 19-24% in Kanpur, Patiala, and Assam and <10% in Delhi. Observed spatio-temporal variations in ABB sources and composition over India call for region specific solutions through airshed-based management.