Air pollution rose significantly across dozens of international cities after the U.S. government shut down a long-running program that monitored local air quality at embassies worldwide, according to a new study. Researchers found that satellite-measured pollution levels jumped by 24% to 33% in the months following the program's sudden closure.
The monitoring initiative began at the U.S. Embassy in Beijing in 2008 and eventually expanded to more than 80 embassies and consulates. By publishing real-time measurements, the program provided reliable public data in countries with limited monitoring systems of their own, helping raise awareness and encourage local environmental regulations. However, the Trump administration shuttered the program in March 2025, citing monetary costs.
To evaluate the consequences, Columbia University climate researcher Zoey Yiyuan Zhou and her team analyzed satellite data across 46 cities. While air quality trends were steady before the shutdown, satellite measurements showed pollution increasing about three to four months after reporting stopped. The researchers estimated this translated to roughly a 4% increase in PM2.5—fine particulate matter that can penetrate lungs and bloodstreams. The highest spikes occurred in Southeast Asian cities, including Manila, Rangoon, and Vientiane, as well as locations with few alternative monitoring tools.
Experts suggest that removing public data reduced scrutiny on polluters. Eric Zou, an environmental economist at the University of Michigan, noted that embassy data acted as an independent auditing tool that discouraged illegal emissions. When monitoring ceased, industrial facilities may have cut compliance costs by reducing pollution controls. Although pollution levels backed down somewhat after peaking—possibly because local or private monitoring began to fill the gap—researchers emphasize that open data is crucial to maintain accountability.
The State Department declined to comment directly on the study published in PNAS, but stated to NPR that it is in the process of restoring public reporting of air quality monitoring data. However, the agency did not provide a specific timeline for when the data feeds would resume.