Living with smog

The material, structure and the method of wearing a mask are important, according to Li Guimei, the secretary-general of China Nonwovens and Industrial Textiles

Ordinary cotton face masks are not designed to trap PM2.5, even though they can block large particles, says Li at an air-pollution protection forum held in Beijing in February.

Besides, as the domestic mask market is still developing, there is no nationwide official criteria and regulation on the categorization and use of different masks. As a result, many of the mask sellers claim their products are able to protect people from PM2.5. But they are made of materials that do not block PM2.5, or do not fit and seal the nostril and mouth areas, Li says.

Masks made of special materials - not just cotton - that have been confirmed to be able to block PM2.5, seal around the face tightly and do not have very big respiratory resistance are the best, Li adds.

As for air purifiers, sales increase in pace with growing awareness of PM2.5, but consumers may become confused on how to choose among so many brands and types, especially when there is no official criteria and testing method on an air purifier's ability to remove PM2.5 in the air, according to Wu Jixiang, an expert with Shanghai Jiaotong University.

A non-governmental consumer-rights protection organization in Shanghai reported in 2013 that almost all the air purifiers it tested exaggerated their ability to remove PM2.5, Wu adds.

Wu suggests customers seek advice from trustworthy professionals when choosing an air purifier, or use a hand-held PM2.5 measuring device to measure the efficiency of the machine. It is also important to follow the instruction of the user's guide to make good use of an air purifier, Wu adds.

Xu Qiong, the Beijing resident, says depending on masks and air purifiers to protect against air pollution are not long-term solutions. Instead, the government should take efficient action to clean the air as soon as possible.