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Be Smart When Choosing an Air Purifier - CHOICE # 414

  • 2011.04.15

Consumers purchase air purifiers to remove smoke and dust and to purify the air indoor. A recent test on air purifiers, however, reveals that: some models have problems in their safety level; there are discrepancies of air purifying ability among samples; and in some cases, the effective purification area claimed by tested samples is very much exaggerated.

The Consumer Council conducted a number of tests on 10 models of air purifiers, with prices ranging from HK$ 629 to HK$ 4,000. Among the tested models, 7 were large size purifiers and 3 were considerably smaller.

On safety performance, 4 models were found to provide insufficient insulation protection or insufficient thickness of insulation materials, which would increase the possibility of an electric leakage. On the other hand, some models also had inadequate heat and flame retardant capabilities in some plastic parts. The small flames in 4 models failed to self-extinguish in the glow-wire test.

Heat resistant and flame retardant capabilities are very important features for air purifiers, since they usually operate continuously for a long period of time. The Council urges the manufacturers to improve on the design of the products by using materials which are more resistant to heat and to ignition.

The labelling of some models was found to be unsatisfactory. Their instruction manuals carry no warning for children and elderly users, which is stipulated in the latest amendments of the international standards.

The usable area of air purification is an important factor to consider in choosing an air purifier. According to the US AHAM (Association of Household Appliance Manufacturers) formula, the maximum usable area (in sq. ft.) for an air purifier is 1.5 times of its CADR (Clean Air Delivery Rate). Calculations based on the test findings of CADRs showed that, all tested models which carry claims of usable area came up with a smaller area than that they claimed. For the large models, the shortage varied from 12% to 67%, and for small models, the shortage was up to 80% to 90%.

There are new products on the market which are advertised as plasma ion generators to suppress the activities of viruses, decompose harmful contaminants, de-activate airborne bacteria and allergens, and suppress the growth of moulds. The Council tested one of these products which did not contain any high efficiency particulate air filter. It was found that its effectiveness in removing pollutants like smoke, dust and pollen was far from satisfactory.

If you are planning to buy an air purifier for removing smoke and dust in the air, consult the latest issue of CHOICE, which reminds consumers to take heed of the followings when they make their decision:

  • Look at the description of the appliance: an air purifier or air cleaner is more likely to serve the purpose of air purification or removal of smoke and dust.
  • Look for CADR information of the product.
  • Alternatively, examine if the model has a high efficiency particulate air (HEPA) filter and a powerful fan as both work towards effective removal of smoke and dust.

Indeed, air purifier is not the only option for improving indoor air quality. Eliminating the source of pollutants, and maintaining good ventilation and household hygiene are the basic and simple steps to keep indoor air fresh and clean.

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