Nearly 90 percent of the 200 cities beset by the world’s highest levels of deadly micro-pollution are in China and India, with most of the rest in Pakistan and Indonesia, researchers reported Tuesday.

Taking population into account, Bangladesh emerged as the country with the worst so-called PM2.5 pollution, followed by Pakistan, Mongolia, Afghanistan and India, according to the 2019 World Air Quality Report, jointly released by IQAir Group and Greenpeace.

China ranks 11th.

Particulate matter of 2.5 microns or less in diameter — roughly 1/30 the width of a human hair — is the most dangerous type of airborne pollution.

Microscopic flecks are small enough to enter the bloodstream via the respiratory system, leading to asthma, lung cancer and heart disease.

Among the world’s megacities of 10 million or more people, the most PM2.5-toxic in 2019 was the Indian capital New Delhi, followed by Lahore in Pakistan, Dhaka in Bangladesh, Kolkata in India, Linyi and Tianjin in China, and Jakarta, Indonesia.