Shopping malls in China’s smog-bound capital are vying for customers by advertising the quality of their indoor air, as weeks of choking winter pollution keeps families indoors. 

Chinese malls rely heavily on children’s play areas, restaurants and even gimmicks such as polar bears to lure shoppers, in a highly competitive sector plagued by massive overbuilding. That poses a problem on days when hazardous air quality keeps families with small children at home, leading many malls to turn to cleaner air as a selling point.

Average air quality in Beijing had improved over the past year, but a bout of thick winter smog beginning in November has had citizens, and particularly parents, griping. Air indexes have stayed stubbornly in the “hazardous” zone in the capital, while the industrial cities of the north China plain have gone off the charts for several days running.