This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For more than a decade, U.S. embassies and consulates provided independent, publicly available air-quality readings in cities around the world. When that program was suspended in 2025, pollution increased in those cities, according to new Climate School research.
Using satellite observations across 46 cities, researchers found that the loss of embassy reporting was followed by about a 33% increase in aerosol pollution. The increases were largest and most persistent in places without another publicly available national air-quality monitoring system. To estimate the impact of losing embassy monitoring on fine-particle pollution, the researchers compared the satellite data with embassy readings collected before the shutdown.
They found an increase of about 1.9 micrograms per cubic meter of PM2.5, the tiny airborne particles that can penetrate deep into the lungs. The authors also tested alternative explanations and found little evidence that pollution was already rising in those cities before the reporting stopped. "Public access to trusted environmental data appears to be part of what creates accountability for pollution," says lead author Zoey Zhou, an assistant professor at the Columbia Climate School.
"Data is evidence, and we're seeing a trend not just internationally but in the U.S. of ending programs that gather climate and environmental data." Why it matters: The findings suggest that environmental transparency can function as a form of environmental governance. When credible, real-time pollution information disappears, some of the environmental gains associated with public disclosure may weaken. Other Columbia-affiliated authors: Fanyu Wang and Douglas Almond, Columbia University.
Hundreds of millions of people live in densely built, poorly connected neighborhoods that can signal serious living-condition deficits. Mapping these patterns across 5,132 cities in Africa, Asia and Latin America and the Caribbean, a new study estimates that about 395 million people live in such neighborhoods. Africa had the highest relative prevalence of people living in deprivation, at 43.6% of urban residents.
About 136 million people, or more than one-third of the total, live in small and medium-sized cities (less than 1 million residents) that are often overlooked in global urban data and policy discussions. The study builds on the City Segments Layer developed by Dana Thomson of the Climate School's Center for Integrated Earth System Information (CIESIN) and colleagues. The layer divides cities into standardized, neighborhood-sized units using open data on roads, waterways, buildings and population.
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