NEW DELHI — For years, this sprawling city on the Yamuna River had the dirtiest air in the world, but few who lived here seemed conscious of the problem or worried about its consequences.
Now, suddenly, that has begun to change. Some among New Delhi’s Indian and foreign elites have started to wear the white surgical masks so common in Beijing. The United States Embassy purchased 1,800 high-end air purifiers in recent months for staff members’ homes, with many other major embassies following suit.
Some embassies, including Norway’s, have begun telling diplomats with children to reconsider moving to the city, and officials have quietly reported a surge in diplomats choosing to curtail their tours. Indian companies have begun ordering filtration systems for their office buildings.
“My business has just taken off,” said Barun Aggarwal, director of BreatheEasy, a Delhi-based air filtration company. “It started in the diplomatic community, but it’s spread to the high-level Indian community, too.”
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After Dr. Apte gave a presentation about Delhi’s air pollution to a hall packed with anxious parents recently at the American Embassy School, the administration invested in indoor air filters and increasingly restricts children’s outdoor activities when pollution levels are especially high. Even so, the sidelines during school soccer games are lined with players’ medicinal inhalers.
“I’m surprised kids there can even play soccer,” said Dr. James Gauderman, a professor of preventive medicine at the University of Southern California and an author of a landmark 2004 study on the effects of air pollution on children’s lungs.
In his study, Dr. Gauderman found that children raised in towns with PM2.5 levels of 30 had substantial reductions in lung function compared with those raised in towns with levels of 5. In the decade since his study was published, “we don’t see any evidence that functional loss is reversed,” Dr. Gauderman said. “The deficit appears to be permanent. I can’t imagine what that deficit would be with pollution levels almost 10 times higher. No one has studied that.”
A version of this article appears in print on February 15, 2015, on page A6 of the New York edition with the headline: Delhi Wakes Up to Problem It Cannot Ignore. Order Reprints| Today’s Paper|Subscribe
