Monsoons in South Asia affected by improved air qualityA new study suggests that as countries across Asia clean up their air, the South Asian summer monsoon, upon which over a billion people depend for water and agriculture, is likely to strengthen. While aerosols are a major cause of air pollution, they also influence climate by scattering or absorbing sunlight and altering cloud behavior. As nations tighten air-quality regulations in the coming decades, the researchers wanted to know how monsoon rainfall would respond depending on whether the pollution cuts happen in South Asia, East Asia or globally. Cutting aerosols worldwide produces an even larger rainfall increase, because it also shifts global atmospheric circulation patterns in ways that favour more moisture reaching South Asia. Air pollution causes millions of premature deaths across Asia each year, so emission cuts must remain urgent health priority.