Clearing the air about purifiers

Rating: NNNNN Q: I'm thinking of buying an air purifier. Any tips? A: No matter how mild the weather is for.

Rating: NNNNN

Q: I’m thinking of buying an air purifier. Any tips?

A: No matter how mild the weather is for January, we’re entering the post-festivities phase of winter when we collectively cozy into bunker mode. But sealing yourself in with the windows shut tight means the air in your home is as about as fresh as your ski socks after a heavy round of shovelling.

Most of us are breathing in all sorts of irritating indoor air pollutants, including animal dander, dust and mould. Canadian org Clean Production Action also found endocrine-disrupting compounds in the vacuum cleaner dust of 70 per cent of the homes they tested. But before you run out and buy an air purifier, you need to know your stuff. It seems there’s more controversy in the world of air filters than in the run-up to the election.

Consumer Reports magazine did a big review of purifiers (whose popularity has exploded in the U.S. post-9/11), but it only tested for smoke and dust removal, although most filters can’t really rid the air of many of the particles in smoke. One company filed a complaint with the Federal Trade Commission against Consumer Reports, accusing it of shoddy research and biased, big-biz-friendly reporting. But despite all the name-calling, we think we’ve got some answers for you sort of.

There’s lots of hooplah about HEPA purifiers. They’re used in hospital operating rooms and can be excellent air filters, but cheaper models are often more hype than help. Still, if you invest in a good one, it’ll rid the air of allergens like mould, dust, pet dander and pollen.

However, most standard HEPAs can’t catch the smallest particles, including viruses, bacteria, smoke, soot and smog. Some models combine HEPA filters with ultraviolet light, purportedly to sterilize bacteria, but the verdict isn’t in on whether cheapy ultraviolet filters actually do this successfully. The Clarifier brand HEPA and ultraviolet light air purifier is supposed to be good, though.

Carbon filters are said to rid your home of funny odours and gases, but not all are created equal. According to the Allergy Buyers Club, which has done a detailed review of purifiers, activated carbon filters are best at removing some heavier volatile organic compounds, or VOCs, from the air. However, they don’t get the lighter ones, like formaldehyde offgasing from particle board, and don’t work so well in humid conditions. As with the ultraviolet systems, you should really only bother with carbon if it’s combined with a good-quality HEPA filter. Consider buying a model with a multiple filter system that includes a pre-filter to keep large particles like pet hair from clogging your finer filter.

Negative ionizers, by the way, are generally bad news. Yes, you’ve probably heard negative ions are wonderfully soothing. They even cling to dust particles, making them heavy so they fall to the floor, thereby “cleaning” the air that is, until you kick the particles back up. In addition, the American Lung Association says harmful particulates that have been ionized by these electronic air filters have a better chance of sticking to your lungs.

Ozone machines are perhaps the dodgiest of electronic air purifiers. Hotels sometimes use them to rid the air of smoke smells after guests leave. But airing out is required, since too much ozone is definitely harmful, and it may react with chemicals in the air to create other harmful pollutants.

Media-charged filters, the better type of electronic air purifiers, are quieter than HEPAs but have to be cleaned frequently to keep them working.

Bottom line: if you’ve got very minor allergies, a cheaper HEPA might work for you, although I wouldn’t believe all the claims on the box. If you have serious allergies and/or multiple chemical sensitivities, you have to pull out the big guns. AllerAir is considered the best for those with MCS (available at Grassroots on Bloor or Danforth from $374.99). The top of the line is Swiss-made IQAir’s HyperHEPA system, endorsed by the American Lung Association and used by hospitals in Hong Kong post-SARS (from $995 at Clearlight Holistics in Ajax, order online at, 1-866-330-7668). Clarifier, Austin Air, Hamilton Beach and Blueair are some other good brands to look for (see for reviews and orders).

Some general shopping tips: find out how often per hour the machine exchanges the air in a room. (Anywhere from two to eight times is standard, although two exchanges won’t do much unless you’ve got a top-notch HEPA filter.) If you think you’d be sensitive to the hum of a HEPA, consider getting a machine made for a larger-size room so you can run it on a lower (and quieter) speed.

For those of you with forced air, Consumer Reports suggests a cheapy furnace filter like 3M Filtrete Allergen filter to control airborne dust, pet hair and dander ($24.99 at Canadian Tire).

If you can’t afford a decent air purifier, fear not. You can get rid of a sizable amount of allergens by dusting your home with a damp cloth and vacuuming regularly. Cracking the windows now and then may be the simplest and cheapest way of all to clear the air.

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