Toward cleaner air for a billion Indians

Exposure to fine particulate matter (PM 2.5 ) is a major risk factor for premature death (1). Few regions of the world experience ambient PM 2.5 concentrations as high as the Indo-Gangetic Plains (IGP), home to more than a billion people in India, Pakistan, Nepal, and Bangladesh. Ground-based monitoring data are incomplete in these countries. However, a robust body of evidence from satellites, urban monitors, and chemical transport models indicates that average population exposures to ambient PM 2.5 are 75 to 100 g m -3 (Fig. Health consequences of this pollution are severe. In India and other south-Asian countries, ambient PM 2.5 ranks among the largest risk factors for premature death (1), shortening life expectancy at birth by 1.5 to 1.9 y What types of emissions controls might it take to substantially address this major health challenge? In many settings, air pollution control efforts focus on large, visible sources such as electric power generation, industry, and transportation. In PNAS, Chowdhury et al. (5) reframe this debate for India by showing that mitigating household air pollution sources-especially cooking and heating with wood and other solid fuels-is an essential component of effective air pollution control.