With smog plaguing large areas of China, especially Beijing and Shanghai, air purifiers and masks are joining the list of top gifts that Chinese bring home from the US for family members and friends.

The list already included luxury goods, health products and milk powder.

"I have bought 15 masks and plan to buy an air purifier to bring back to my family at the end of this month," said Bing, a Chinese PhD student studying mechanical engineering in New York, who did not give her full name.