Ahead of President Barack Obama’s visit to New Delhi in January, the US embassy, worried over the quality of the capital’s air, purchased 1,800 air purifiers for use on the mission premises. With persistent smog over Delhi since Diwali, and increasing awareness of air pollution across India, sales of air purifiers have seen a remarkable spike.

Philips has reported a 20-30% surge in sales this year, and Eureka Forbes, which was one of the first to enter the Indian market in 1996, says it is now selling 7,000-10,000 machines a month, as compared to 10,000-20,000 per year a few years ago. Blueair, the Swedish company that supplied the air purifiers to the US embassy, says the last six months have seen the “most activity” in their six years in India — with a “3-4 times jump” in sales since Diwali.

Customers in Delhi NCR have been driving the bulk of these sales, say the companies, most of which have begun providing home consultancy services as well.