The Air Pollution Tradeoff in India: Saving More Lives Versus Reducing the Inequality of Exposure

Chronic exposure to ambient fine particulate matter (PM 2.5 ) represents one of the largest global public health risks, leading to millions of premature deaths annually. For a country facing high and spatially variable exposures, prioritizing where to reduce PM 2.5 concentrations leads to an inherent tradeoff between saving the most lives and reducing inequality of exposure. This tradeoff results from the shape of the concentration-response function between exposure to PM 2.5 and mortality, which indicates that the additional lives saved per unit reduction in PM 2.5 declines as concentrations increase. We estimate this concentration-response function for urban areas of India, finding that a 10 unit reduction in PM 2.5 in already-clean locations will reduce the mortality rate substantially (4.2% for a reduction from 30 to 20 µgm -3 ), while a 10 unit reduction in the dirtiest locations will reduce mortality only modestly (1.2% for a reduction from 90 to 80 µgm -3 ). We explore the implications of this PM 2.5 /mortality relationship by considering a thought experiment. If India had a fixed amount of resources to devote to PM 2.5 concentration reductions across urban areas, what is the lives saved/inequality of exposure tradeoff from three different methods of employing those resources? Across our three scenarios—1) which reduces exposures for the dirtiest districts, 2) which reduces exposures everywhere equally, and 3) which reduces exposures to save the most lives —scenario 1 saves 18,000 lives per year while reducing the inequality of exposure by 65%, while scenario 3 saves 126,000 lives per year, but increases inequality by 19%. Funding: None to declare. Declaration of Interest: Authors declare no competing interests Ethical Approval: Not applicable for this study.