The 10 cities with the worst air pollution all have one thing in common

India is the standout country in a new worldwide report — and not in a good way.

A study on global air quality from the World Health Organization finds that India’s cities have the dirtiest air, while U.S. cities are relatively clean and China is cleaning up its act.

Nine out of 10 people around the world breathe polluted air, the study found, and that dirty air kills 7 million of us every year. Things appear to be getting better in the most polluted cities, if only marginally, with particulate matter concentrations dropping in the ten most polluted places fractionally since the last set of WHO data was released in 2016. And air in the U.S. is relatively clean, but under EPA chief Scott Pruitt, the regulations that keep it that way are being eroded.

Every city in the World Health Organization’s top 10 most polluted cities is in India, if measured by the smallest and deadliest type of particulate matter air pollution. This type of pollution is generated primarily by exhaust from cars and smokestacks, as well as fires.

Many of the deaths associated with dirty air are the result of indoor stoves — the WHO estimates that those are responsible for an additional 3.8 million deaths annually. They’re a huge problem in India, where poor people don’t have the means to construct adequate ventilation systems to keep their air clean while they cook.

“Many of the world’s megacities exceed WHO’s guideline levels for air quality by more than 5 times, representing a major risk to people’s health,” Dr. Maria Neira, a World Health Organization researcher, said in a statement. Particulate matter contributes to all sorts of lung and heart problems, from aggravated asthma to heart attacks and premature death.

The report comes as China — historically among the most polluted — has taken enormous steps to clean up its act, even if it’s done so by denying heat to the country’s poor in the winter months. In an effort to keep its air breathable, China recently shut down major power plants across the country, causing power shortages.

Cities in the U.S. look very good compared to cities like Delhi. Even the dirtiest city in the U.S., Bakersfield, California — where oil refineries, agriculture, car emissions, and rail freight together create a smoggy horizon — still ranks way down the WHO’s list, at 814th.

“Political leaders at all levels of government, including city mayors, are now starting to pay attention and take action,” Dr. Tedros Adhanom Ghebreyesus, director-general of WHO, said in a statement.

That may be true in most places, but it’s not true of EPA chief Pruitt. The well-documented friend of fossil fuels has appointed a researcher to his science advisory board who thinks “modern air is a little too clean for optimal health” and surrounded himself with people — including Steve Milloy, who served on the EPA’s transition team and has remained close to the agency — who don’t believe that air pollution is nearly as harmful as the scientific community would have us believe.

The EPA announced in April that it would roll back tailpipe emissions standards, aimed on reducing smog and carbon pollution, and sought to limit the types of studies that can be used in their policymaking. Under Pruitt’s proposed “secret science” rule, only studies that release all of their raw data can be considered in policymaking. The American Lung Association is concerned that this rule could target some of the longstanding, sound studies that were used to craft U.S. clean air policy.

Cover image: Photo taken on Oct. 20, 2017, shows a street in New Delhi with heavy smog as air pollution spikes in the Indian capital. (Kyodo via AP Images) ==Kyodo