Growing up in South Korea, Heesung Chong was acutely aware of air quality. “The aerosol pollution is relatively severe in South Korea. On bad days, you could feel it,” he says. The air on such days ...

Mumbai, India—In Chandrapur, a city in central India of about 466,000 people, air pollution affects one of every three households. People develop respiratory diseases like asthma and bronchitis, skin ...