Study Finds Air Pollution Rose After Trump Administration Ended Embassy Monitoring

The program began in 2008, when U.S. officials installed an air quality monitor on the embassy in Beijing and began making the information public. It later expanded to more than 80 embassies and consulates. Research has suggested the monitoring contributed to measurable improvements in air quality, especially in many low- and middle-income countries with limited monitoring systems of their own. The Trump administration closed the program in March 2025, citing monetary costs. The State Department did not respond to a request for comment in time for publication.

Eric Zou, an environmental economist at the University of Michigan who grew up in Shanghai in the early 1990s, said the U.S. data helped change how people understood severe smog. "When you have a big smog event, people often talk about that as fog, they think it was just like bad weather," he said. "Once you have pollution information, it tends to be that it actually helps people to realize, 'Oh I actually value air quality.'"

For the new study, Zoe Yiyuan Zhou, a climate researcher at Columbia University, and colleagues compared air pollution levels before and after monitoring ceased across 46 cities. Because they did not have on-the-ground measures for the latter part of the comparison, they used satellite data for both periods. "It's such a rare case to study this drawback," Zhou said.

The team found no significant trends in air pollution over the 300 days before U.S. reporting ended. About three to four months after reporting ended, however, pollution had gone up by about 30 percent on average. Satellite data is not a perfect substitute for monitors that measure on-the-ground pollution, and the researchers estimate their satellite measurements translate to about a 4 percent increase in PM2.5, the small suspended particles that can enter the lungs and bloodstream and cause health problems.

Andrea La Nauze, an environmental economist at Deakin University in Australia who has researched the benefits of the program but was not involved in the new study, called the work "a great study, high quality" and "a real pity." She said the program "led to sustained improvements in air quality that were continuing to increase after 10 years," and that the new research suggests those improvements are not guaranteed if monitoring stops. "That magnitude is certainly concerning," La Nauze said. "Particulate matter is a serious and dangerous thing, and being exposed to it is not good."

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

The study cannot say why pollution increased after monitoring stopped. Zou said that for countries with non-existent or nascent monitoring programs, U.S. data may have prompted more regulatory action. "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?'" he said. In many industries, Zhou said, it costs money to cut down on pollution, and when monitoring stops, companies may see it as an opportunity to cut those costs.

The researchers did find some potentially hopeful news. Pollution levels seemed to go back down somewhat after peaking about three or four months after monitoring stopped. Zhou said it is difficult to say why this decrease happened or whether the trend will continue. She suspects it may reflect other forms of monitoring, by individuals or local governments, coming online after the U.S. withdrawal. But not all areas may have the ability to readily make up for what has been lost, she said, especially in regions where air quality monitoring is new.