The unrelenting smoggy weather has triggered a craze for do-it-yourself air purifiers, with some industry experts suggesting that home-made purifiers can as effective as those bought from stores if they meet certain requirements.
A Shanghai woman recently made an air purifier with a fan and a high-performance filter screen she bought online because she was worried about her daughter’s health. It cost her 800 yuan (US$129), the Shanghai Morning Post reported yesterday. Moreover, she had it made in just an hour.
The air purifier is now in her daughter’s kindergarten but the filter screen has turned black, the newspaper reported.
The woman said she was inspired by an expatriate living in Beijing, one of the worst-hit cities for air pollution in China.
Thomas Talhelm, an American, made an air purifier which reportedly helped in filtering out 92 percent of PM2.5 airborne particles after operating it for about eight hours in a 15-square-meter room.
Talhelm uploaded the method of making air purifiers online and there are now classes in Beijing teaching people to make air purifiers at home.
“I plan to improve on it and make another one by wrapping the filter screen with a thin sponge to prolong its duration,” said the woman, identified by a single name Solo.
The sponge is used to filter larger particles, she said.
The home-made air purifiers are winning over residents, who say effective air purifiers are expensive, cheap ones does little, and only home-made ones are affordable and serve its purpose.
Another local resident, surnamed Xi, said he ordered a common fan and a piece of non-woven fabric on e-commerce site Taobao, and plans to make one himself. The total cost was even cheaper — just 50 yuan.
“I think non-woven fabrics have the same effect as high-end filter screens, but are much cheaper, and I will try it after I finish the purifier,” he said.
Xi said air purifiers sold online or at stores cost several thousand yuan. “There are some posts online on how to make air purifiers at home, which is easy to follow,” he said.
But not all of them are sold to the idea that home-made purifiers are better than others.
“It maybe a good idea, but I don’t think its effect can be guaranteed,” said Xu Bin, who works for a Shanghai magazine and has been waiting for more than two weeks for an air purifier for which he paid more than 4,000 yuan.
He was told he would have to wait for at least 20 days as orders piled up at the Swedish firm’s China factory. Its prices have also gone up from about 3,000-plus yuan, Xu said.
Xu already has an air purifier at home. Unhappy with its performance, he decided to go in for an expensive one.
Experts said home-made air purifiers have to meet certain criteria.
“First of all, the fan must blow at its best; secondly, the single filter efficiency should be above 95 percent; and the fan and the filter must be sealed tightly,” said Shen Hao, director of the Shanghai quality supervision and test center of environmental protection products.
But Shen still advised residents to buy air purifiers instead of making them at home because they are solid and have better filtering performance.
Shen suggested that the filter screen be replaced often especially when the air quality index reaches above 300, or severely polluted. If the air quality is fine or lightly polluted, the screen can be used for up to one year, he said.
The smog choking large parts of China has boosted demand for masks and air purifiers, with around 870 million yuan spent on the items this year, online shopping site Taobao revealed earlier this month.