What cheap but reliable air purifiers are available in China?
From left to right: fans by Air-O-Swiss, Midea, Panasonic, Philips, Xiaomi and Smart Air. Photo composite by One-Stop staff
Many expats in China believe that air purifiers are only worth buying if they cost thousands of yuan. What they don’t realize is that all an air purifier really needs is a strong fan and a replaceable filter. All of the LCDs, ionizing options, ultraviolet lights, water vapour spouts and fancy brand names are surplus to requirements (and in the case of the ionizing and ultraviolet options, of dubious benefit).
Provided the fan is strong enough and the filter properly made, that’s really all you need to clear out your home of PM2.5 – the airborne particulate matter that is small enough to get into the bloodstream – and other nasty stuff.
Proof of this was found by Doctor Richard Saint Cyr, a Beijing physician whose English-language blog discusses health issues faced by residents of China. The good doctor performed a series of independent tests on air purifiers, each costing less than 1,000 yuan, and concluded that they could perform just as well as more expensive models, depending on the size of the room that needed clearing.
Dr Saint Cyr chose to test the air purifiers based on the following criteria:
- Priced at under 1,000 yuan
- Famous international brands preferable to Chinese brands
- Machines must be of High-Efficiency Particulate Arrestance (HEPA) standard, or close to it
- Fit for rooms of at least 21 cubic meters in size
- Ability to purify formaldehyde or other volatile organic compounds (VOCs) would be a plus
- He also noted each fan’s Clean Air Delivery Rate, or CADR
Dr Saint Cyr notes that good fans are as important as good filters, and that a machine with a strong filter but a weak fan (one that cannot circulate the air in your room at least five times every hour) will be less efficient than one with a less impressive filter but a better fan.
He also adds that while he mentions the CADR of each fan, is not really a useful factor to consider when buying, as CADR is set by the industry, rather than medical professionals, and is based on a fan’s maximum setting rather than the lower, quieter settings that people are most likely to use when at home (especially when sleeping).
He also tested to see how well the fans dealt with PM0.3, which is considerably smaller than the PM2.5 that many people in China are concerned about. Here are the models he tested, and their details according to the manufacturer:
|Models tested||Price in yuan||Manufacturer claims it can filter…||CADR in cubic metres||Coverage in square metres|
|Smart Air Original||200||99.9 percent of PM0.3||Unknown||11-20|
99 percent of PM0.3
89 percent formaldehyde
99.97 percent of PM0.3
91.2 percent PM0.3
95 percent formaldehyde
99.9 percent of PM0.3
87 percent formaldehyde
99.3 percent of PM0.3
91 percent formaldehyde
After flooding his office with outdoor air, Dr Saint Cyr then set the machines to their maximum settings and tested the room’s PM0.3 levels, first after first 10 minutes and then after 50 minutes (it should be noted that the Xiaomi only stays on its maximum setting for 15 minutes before switching to a lower one, which Dr Saint Cyr suggests may explain why the reduction over time for that machine is less impressive than the other fans’, even though it’s the top performer at the 10-minute mark).
|Models tested||Total % reduction in particulate matter (based on original amount)|
|PM2.5 reduction after 10 minutes||PM2.5 reduction after 50 minutes||PM0.5 reduction after 10 minutes||PM0.5 reduction after 50 minutes|
|Smart Air Original||77||89||53||60|
He then performed additional tests in his bedroom with three of these options, before naming the Xiaomi and Midea models as his picks of the crop. He noted Xiaomi’s impressive performance, although he tempered his enthusiasm by pointing out that it is a new brand best known for cell phones rather than fans; that it doesn’t using the top-rated HEPA filter (although as he points out, the strength of the fan counters that) and, naturally, the company’s lack of a track record.
Nevertheless, he remains enthusiastic about the range and quality of affordable filter systems, and encourages all readers to buy some form of filtration for their homes and offices.
For his full, in-depth analysis of the machines and what they offer, you can check out Dr Saint Cyr’s blog post on the subject.
Useful Chinese words and phrases
|空气净化器||kōngqì jìnghuà qì||Air purifier|
|测试 / 测评||cèshì/cèpíng||Test|