Clear The Air News Blog Rotating Header Image

August, 2003:

Buying an Air Purifier

Published in the SCMP:

Everything you need to know about buying an air purifier
Peta Tomlinson

THERE’S NOTHING LIKE a bout of Sars to get us thinking about the air we breathe. According to the Environmental Protection Department (EPD), indoor air pollution can be responsible for irritations of the eyes, nose and throat, headaches, dizziness and fatigue, as well as asthma and lung disorders.

Sars was the trigger that sent hundreds of consumers rushing to buy air cleaners earlier this year, and two of Japan’s major manufacturers, Matsushita and Sharp, had to increase production to cope with demand. So, what do they actually do? And how do they differ from an ordinary air-conditioner?

While some air-conditioners have air-purification mechanisms – certain models by Sharp, Whirlpool and Brandt, for example – air cleaners or purifiers have additional filter functions.

Generally, air cleaners use four types of air filters: general filters, capable of removing bigger particles or dust in the air; HEPA (high-efficiency particle air) filters, effective in removing 99 per cent of dirty air particles down to 0.9-1 microns; carbon filters, containing active carbon which combats unpleasant odours; and iconic filters, which produce negative ions causing pollutants to magnetically draw together and settle on the floor or other surfaces for easier cleaning.

Units with HEPA filters also capture bacteria and are generally regarded as being best for those with nasal allergies or sensitivity to flowers, and are often the top choice for homes with young children. Beware of terms such as ‘HEPA-type’ or ‘HEPA efficiency’: this may not mean the unit has a HEPA filter.

Always ask about noise levels. Because HEPA filters work only when air is drawn through them, this can necessitate a large motor to power the filtering process. Most machines will require regular changing of filters, so be aware of maintenance costs.

Japanese brand Sharp ( and Israeli brand Amcor ( make the biggest-selling air cleaners at Fortress stores (tel: 2555 5788; Sharp’s Plasmacluster model FU-888SV, which covers 31 square metres and retails at $2,680; and Amcor’s AP 2000, which covers 29 square metres and is priced at $1,180.

Sharp has donated 26 Plasmacluster units to the Hong Kong Adventist Hospital, which have been installed in the surgical and urgent-care wards, maternity, paediatric unit and playroom, and the out-patient’s clinic. ‘Before we accepted the gift, we asked our clinical staff to look through the scientific papers and reports from a number of sources to check whether the claims made by Sharp were true,’ says director of business development Jeremy Low. ”Our clinical staff said the machines did help in cleaning up the various agents, viruses and most bacteria in the areas these machines were located.’

An on-site assessment of your home or office is available from independent air-quality testers such as Desmond D.B. Chan of Acoustics and Air Testing Laboratory (2/F, 190 Prince Edward Road West, Kowloon, tel: 2668 3423; The firm conducts a 12-point test following guidelines proposed by the EPD, which costs $6,500 for eight hours of continuous testing, or $3,500 for surrogate testing (in which four areas are tested for a half-hour period). Although the firm, being independent, does not make recommendations, householders can check results against the guidelines on the EPD website (

For more details on how to improve your indoor air quality, visit the government’s Indoor Air Quality Information Centre in Kowloon Tong (78 Tat Chee Avenue, tel: 2788 6177;

Air cleaners should be used in conjunction with effective source control and adequate ventilation.