Air quality worsened across Asia after U.S. embassy monitoring program ended

A new study published in PNAS links the termination of the U.S. embassy air-quality monitoring initiative to a sharp uptick in atmospheric pollution across 46 Asian cities. Using satellite observations, the authors observed no clear trend in the 300 days before the program’s closure, but pollution rose by about 30% roughly three to four months after monitoring stopped. This translates to an estimated 4% increase in harmful PM2.5 particles, which can penetrate lungs and the bloodstream.

The most affected locations were Southeast Asian capitals, including Manila, Rangoon and Vientiane, especially where alternative monitoring was scarce. Researchers note that the U.S. data had previously spurred regulatory action and public awareness, and its removal may have encouraged polluters to cut costs. A slight rebound in air quality after the peak suggests that other monitoring sources, perhaps local or citizen-driven, began to fill the gap. The findings underscore the importance of transparent environmental data for sustaining air-quality improvements.