Buying an air purifier to prepare for allergy and wildfire season? Here's what you need to know.

Here are some tips on how to choose an air purifier.

Cheryl Chan 4 minute read May 24, 2022

An air purifier with HEPA filters can capture 99.95 per cent of dust, pollen, smoke and other pollutants. Jomkwan / Getty Images/iStockphoto

As the weather warms up and people head outdoors, it’s also a good time to pay attention to the quality of your indoor air.

Indoor air can have pollen and dust that trigger allergies in the spring and smoke and fine particulate matter in the summer during a bad wildfire season.

The easiest way to refresh inside air is to ventilate a room by opening doors and windows. But if the room has poor ventilation or there’s already smoky skies outdoors, air purifiers could be particularly useful, especially for people dealing with allergies, asthma or other respiratory issues.

There’s several air purifiers on the market, which do essentially the same thing, said Sarah Henderson, director of environment health services at the B.C. Centre for Disease Control: They draw in air from the room, clean it through a set of filters, and push it back out.

And does it help get rid of COVID-19 germs? Yes, said Henderson. “It’s a double win.” HEPA filters can filter out very small particles, including viruses in the size range of SARS-CoV-2. An air purifier won’t keep your environment COVID-free, but it will help reduce the risk of COVID transmission, she said.

But what’s HEPA? And CADR? What size should I get? Here are some tips if you’re in the market for an air purifier:

Check online reviews. There’s plenty of feedback available online on air purifiers. One tip is to do a keyword search on the reviews. For example, search “smoke” to see how other users rate the product for cigarette or wildfire smoke.

Go with an air purifier that uses a HEPA filter. HEPA stands for high-efficiency particulate air, a type of filter that can theoretically trap at least 99.95 per cent of dust, pollen, smoke, bacteria and other particles with a size of 0.3 microns, according to the U.S. Environmental Protection Agency.

There are other types of air purifiers that operate differently, said Henderson. Electrostatic precipitate puts an electrical charge to particles in the air and attracts them to metallic plates. But it’s more difficult to use and produces ozone, which in itself is a respiratory irritant.

Pick a quiet air purifier — if that’s important to you. One of the reasons people end up not using their machines is because they’re noisy, said Henderson. Be skeptical of manufacturers’ claims on this one and check reviews to see what users say.

Consider picking an air purifier that’ll tell you when to get the filter changed. The purifier will only be as good so long as the filters aren’t clogged. HEPA filters generally last a year depending on use. Some purifiers will give a warning indicator to let you know it’s time to clean or replace the filters. How long the purifiers last depend on how often you run the devices. Replacement filters usually cost $50 and up, depending on brand and size, so factor that into the cost.

No need to go high-tech, unless you want to. Some air purifiers have bluetooth and apps that allow you to control them from your phone. Others have automatic sensors, remote controls, or charcoal or carbon inserts that help remove odours. Such bells and whistles are nice but not necessary, said Henderson. “If you can afford it, maybe it’s worth paying a premium price for them. But they don’t affect the unit’s ability to do its job.”

The Vancouver skyline shrouded in heavy smog from clouds and smoke due to forest fires in Washington, Oregon and California in September 2020. DON MACKINNON / AFP via Getty Images

Get the right size air purifier for your space. Knowing where you plan to use the air purifier is important in helping you pick the right one. As a general guideline, most residential air purifiers come in small (bedrooms, bathrooms), medium (studio, small living rooms) and large (larger rooms like open-concept living and dining areas). The larger the unit, the larger the filter and airflow, but they also come with a higher price tag. “So if you’re on a budget, consider whether can you do a 100-square-foot bedroom and keep that one area of the home cleaner, especially when you’re going to be sleeping there overnight,” suggested Henderson.

Calculate the right CADR. The CADR rating, which stands for clean air delivery rate, is the industry standard for measuring the air flow of filtered air. It’s measured in cubic metres per hour. The Association of Home Appliance Manufacturers, which developed the rating, suggests taking the CADR rating and multiply it by 1.55 to get the room size. For example, a 100 CADR purifier will clean a room size of 155 square feet (based on a ceiling height of eight feet). Generally, the bigger the room, the higher the CADR required. But higher isn’t necessarily ideal, said Henderson. “It’s unnecessary to have a unit with a very high CADR in a small room,” she said. “That’s overkill.”

Shop early. Air purifiers fly off the shelves at the first whiff of wildfire season. So if you know you are sensitive to smoke and other pollutants, prepare ahead and get one early while they’re still available.




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