Air pollution levels rose by 24 to 33 percent across 46 cities in the months after the U.S. embassy air quality monitoring program was shut down in 2025, according to a study published in the journal PNAS. The Trump administration ended the State Department's program to collect air pollution data at U.S. embassies in March 2025.

Researchers compared air pollution levels before and after the monitoring ceased across 46 cities using satellite data. Air pollution levels increased on average by about 30 percent approximately three to four months after the reporting ended.

The study found no trends in air pollution over the 300 days preceding the end of U.S. reporting. Researchers estimate the satellite measurements translate to about a 4 percent increase in PM2.5.

The increase in pollution was highest in Southeast Asian cities, including Manila in the Philippines, Rangoon in Myanmar, and Vientiane in Laos. Pollution spiked more in cities with fewer monitoring alternatives.

Pollution levels decreased somewhat after peaking about three or four months after the monitoring stopped. It is unclear whether this decrease indicates a temporary fluctuation or a return to previous baselines.

Zoe Yiyuan Zhou, a climate researcher, noted the unique nature of the situation. "It's such a rare case to study this drawback," Zhou said.

Zhou emphasized the role of transparency in maintaining environmental standards. "Data is just so important. Having access to information is necessary to make sure that these previous gains can continue. Public information creates accountability."

Andrea La Nauze, an environmental economist, reviewed the findings and the history of the initiative. "It's a great study, high quality. And it's a real pity," La Nauze said.

La Nauze pointed to the long-term effects of the monitoring presence. "The program led to sustained improvements in air quality that were continuing to increase after 10 years," she said.

Eric Zou, an environmental economist, offered a perspective on why the removal of monitors might lead to increased emissions. "Maybe the U.S. Embassy was a really strong force, in terms of a third-party auditing mechanism, and once that's removed, people are like 'Now I can just pollute, right?'" Zou said.

Zou explained how public data influences behavior and valuation of environmental goods. "Once you have pollution information, it tends to be that it actually helps people to realize, 'Oh, I actually value air quality,'" he said.

The Trump administration cited monetary costs as the reason for ending the embassy air quality monitoring program, which had expanded to more than 80 embassies and consulates since its inception in 2008.

Timeline

The State Department's air quality monitoring initiative began in 2008 with the installation of a monitor at the U.S. embassy in Beijing.

The Trump administration cited monetary costs as the reason for ending the embassy air quality monitoring program. A study published in the journal PNAS reported that air pollution levels measured via satellite increased by 24-33% in the months following the shutdown of the embassy monitoring program.

Why It Matters

The State Department's monitoring initiative expanded to more than 80 embassies and consulates before its termination. The events described span 17 years, from 2008 to 2025, marking a period of data collection and potential accountability.

The study indicates that the presence of third-party monitoring served as an auditing mechanism that influenced pollution levels. The removal of this infrastructure coincided with a measurable decline in air quality, suggesting that public information plays a concrete role in enforcing environmental standards.