Signal Air pollution spiked after the Trump administration stopped embassy monitoring

Summary

A study published in the Proceedings of the National Academy of Sciences on Monday, September 15, 2026 found that air pollution increased 24 to 33 percent in 46 cities worldwide after the U.S. State Department halted its independent embassy air-quality monitoring program. The program, which began at the Beijing embassy in 2008 and expanded to more than 80 diplomatic posts, was stopped in March 2025 citing budget costs. PM2.5 particulate concentrations rose an estimated 4 percent following the shutdown. The largest spikes occurred in Southeast Asian cities including Manila, Rangoon and Vientiane, where local monitoring infrastructure is limited. Researcher Zoey Yiyuan Zhou said data access is necessary to sustain prior air-quality gains. The State Department would not comment directly on the study but said it is in the process of restoring public reporting of air-quality data, without providing a timeframe.