A new national standard for air purifiers will help guide the booming market for the devices, which currently lacks supervision, experts said.

Sales of air purifiers increased when Beijing issued smog alerts recently.

"Some best-sellers have already run out of stock. Even though sales decreased a little compared to the beginning of this month, when the first alert was issued, I think it might be because people already have one," said Luo Zhongchao, a sales assistant at electronic appliance vendor Gome.

Growing concerns for the hazards brought by poor air quality have led to a boom in the market for air purifiers.

Last year, sales of air purifiers increased by about 90 percent, with around 200 manufacturers in the market, according to ibaogao.com, a market research report website.

Some large manufacturers, such as Honeywell, that are usually involved in business-to-business operations, will increase investment in the research and development of air purification devices next year.

"But, still, many entered the market lacking the core technology for cleaning air, even though it is neither costly to produce nor a patented technology," said Xu Yanguang, an analyst with the Beijing-based home appliance consultancy All View Consulting. "They simply rushed into the market to have a place."

The chaotic market has seen exaggerated and misleading advertising with little regulation.

"It is quite common to see products labeled with a high cleaning rate for a certain pollutant - say, PM2.5 or formaldehyde - up to 99.9 percent. Cleaning performance results vary in different sizes of test chambers and over time, but customers simply don't know that," said professor Wu Jixiang, a clean air expert with Shanghai Jiao Tong University's Electricity Engineering Department.

The new national standard represents a push to weed out unqualified manufacturers, Wu said.

Starting March 1, the performance of air purifiers needs to be labeled by uniform standards - clean air delivery rate and cumulate clean mass - which specify cleaning capacity and when a filter needs to be replaced.

"These two measures are of the greatest importance to customers," Zhu Tianle, vice-dean of the School of Chemistry and Environment of Beihang Univeristy, said at a forum sponsored by the Clean Air Alliance of China earlier this month.

"From whatever perspective, it is really a good chance to shape the market," said Zhu, adding that supervisory roles need to be further clarified.

"It seems that the environmental bureau should play a major role in regulating the market, but in actuality nonprofit organizations are doing more. There should be someone who will make sure that regulations are in place."