Preventing biogenic secondary organic aerosols formation in India

Biogenic secondary organic aerosols (b-SOA, a subset of PM2.5) are generally assumed uncontrollable, as their precursors are of natural origin. The underlying science that anthropogenic pollutants aid in transforming biogenic volatile organic compounds (b-VOC) into the b-SOA opens the avenue to prevent b-SOA formation through anthropogenic emission control. Sixty customised Weather Research and Forecasting-Chemistry (WRF-Chem) model simulations were undertaken for India in 2018. Five pollutants, TC(BC + OC), NOx, NMVOC, NH3 and SO2, were considered for emission reductions at three levels 25, 50 and 75%, and the resulting prevention of b-SOA formations was examined. TC and NOx emission control showed maximum potential in preventing b-SOA formation. A 10% reduction in TC emission prevented 4.5% b-SOA formation, and a similar reduction in NOx prevented 3.7% b-SOA across all seasons and regions. The residential combustion contributing 57% of TC emissions was one single important source for TC control, and for NOx, it was vehicles and coal-based power plants (emission share over 80%). Specific reductions in anthropogenic emissions have been presented seasonally and regionally to prevent b-SOA formation.

Automated summary

A study has found that controlling anthropogenic emissions can effectively prevent the formation of biogenic secondary organic aerosols (b-SOA). Among the pollutants considered, the control of carbonaceous aerosols and nitrogen oxides (TC and NOx) showed the greatest potential. Residential combustion was found to be the main source of TC emissions, while vehicles and coal-based power plants were the main sources of NOx emissions.