Do air purifiers work? Everything you need to know according to experts

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The Environmental Protection Agency says North Americans spend about 90 per cent of their lives indoors and for some, purifying the air can help improve their health by diminishing or avoiding everything from minor irritation to more severe illness.

We talked to two academics who know a thing or two about air quality to find out how a purifier works, what to look for when buying one and even picked up some do-it-yourself tips.

Professor Michael Brauer who works in environmental health at the UBC School of Population and Public Health says air purifiers have their benefits but that doesn’t necessarily mean you have to go with the most expensive option to get the job done.

He said ones that “really clean the air and in some cases improve health need to have HEPA filters.” 

“We tend to focus on the filtration, the removal of particles. Either it is wildfire smoke or pollution from traffic or a wood-burning stove or even things like COVID,” he said. “I’m saying that because they really only efficiently remove the particles but won’t remove gasses. If for instance, you have a strong odour in home that is most likely a gas, very few air cleaners will remove gasses for a long period of time or effectively.”

He warns to steer clear of products that are often sold online “but should not be allowed to be legally sold,” such as ozone generators.

“The more sophisticated air cleaners will have ionizers. We generally don’t recommend them because they are creating more harm than good,” Brauer said. “The general rule is simpler is better. And make sure you have HEPA filter.”

“The more bells and whistles you get, the more you get into the potential it may do ionizing and the more likely something is gonna break. Simple is best and usually cheaper,” he said. 

“Probably more important than brand is (the question) is it sized appropriately for the space you are operating it in?”

He says a purifier needs to be run where you are and when you are there. The bedroom is the first candidate for one while the second might be a family room. 

Furnace filters are important, but that’s a whole other topic. In short, the professor also recommends those who have forced air to invest in a good-quality furnace filter like a HEPA or a Minimum Efficient Reporting Value (MERV).

When picking a particular portable purifier model, Brauer says how much noise it makes is a consideration given some are so noisy they are not conducive to sleep.

His overall take on purifiers? They are fantastic for some people but albeit perfectly harmless, not a requirement for everyone.

“It really depends on what and who. If you have breathing sensitivities or pre-existing lung or heart disease, they do work quite well,” he said. “It also depends on what you are trying to filter out. I don’t think it is something everybody needs.”

If you live near a major intersection, in a polluted part of a city or an area affected by wildfire episodes or residential wood burning, it can be a good investment.

Pet dander allergies? Yes and no. A number of studies show people who are allergic or asthmatic will find air filters helpful but not sufficient.

COVID-19? Brauer says an air purifier can lower the number of viral particles in the air, which would suggest you are less likely to become infected. But that won’t likely protect you much if you are talking face-to-face with someone with the virus. If it’s a concern, he says “two people wearing a mask is much more effective than operating an air purifier.”

When to run it: Generally, you operate it when you are there. If you are not at home and operating it, it’s certainly clearing the air but you are not getting any benefit. You don’t have to keep the space constantly clean.” Also, close the windows when you run your purifier.

Size matters: Match the area the manufacturer says it will clean to the space you intend it to work in.

Other tips to clear the air: 

Israel Dunmade, professor in the Earth and Environmental Science Department at Mount Royal University, agrees. 

He says the best way to remove pollutants from indoor space is to “eliminate the source of that pollution,” and the second approach is to ventilate your home.

“It is necessary to regularly open our windows,” he said, adding an hour or two is typically sufficient to allow for pollutants to escape or be diluted. “Our homes are like an envelope and the purpose is to prevent the loss of heat in the winter … however, it is important to regularly open our windows to allow fresh air to come in and allow the air that we breathe out to escape.”

“The third one is where the air purifier comes in,” Dunmade said. “However, when we talk about cleaning the air, there are two approaches.”

He says the first is to ensure the furnace or air conditioner has a good filter which is regularly changed. Portable purifiers, he stresses are “generally capacity limited and the ability to purify is also limited,” to a single room while a furnace filter takes care of the entire home.

Like Brauer, he says the best purifier isn’t about the brand but ensuring it has a HEPA filter.

He says that is backed by research showing a HEPA filter “can theoretically remove about 99.97 per cent of airborne particles,” up to a certain size, including dust, pollen, mould and bacteria. 

How long should you run it? Three hours several times a week to maximize benefits.

Who should get one: “People with allergies and asthma can benefit from it. People without those problems, eliminating sources of pollution and ventilating the  house will be enough.”

Types to avoid: Ozone generating air cleaner, electronic air cleaner or ionizing air cleaner which cause more problems than solutions.

The Filtrete Smart Room Air Purifier and air quality monitor were recently in Canada to provide cleaner air and help the nearly 9.5 million Canadians who suffer from seasonal allergies. 

According to Filtrete, “indoor quality is often worse than outdoor air quality and you spend most of your time indoors.” And their machine captures up to 99.97 per cent of airborne particles and has advanced technology to help people breathe with ease.  

It works with Alexa or Google Assistant for those who download the Filtrete smart app. But there are also buttons right on the machine. A colour-coded rating scale shows you air quality at a glance. 

Particles captured by the Filtrete: 

Summary: I am a rookie in the air purifier world so could very easily be duped by any product. But I did my research and I put the Filtrete to the test in several ways and was really impressed.

Setting it up: Shockingly, I managed to do this without reading the instructions, calling a 1-800 helpline or searching Google. Plugged it in and figured out what to press on the machine. It went like this; on button, auto fan, two-hour timer. Ba da bing! 

How it works: The Filterete Smart Tower relies on laser-based air quality sensors to detect microscopic particles in the air. If it detects poor air quality, it automatically adjusts fan speed to work harder and more quickly at improving it. 

Extras: Link up with the smart app to receive alerts on your phone when poor air quality is detected and when it’s resolved. The actual machine and the app tracks your filter life giving you the percentage of life remaining. This way you have no excuse to miss a filter change.

This purifier is refreshingly user-friendly but does it work?

Once I found a spot and plugged it in, the slick white purifier (it’s available in white only) seamlessly blended in. Once it was on, it wasn’t noisy. 

The tower is designed to tackle air quality in a space of about 100 sq-ft. But my main level is an open concept of about 500 sq-ft. Either way, it seemed to do a good job. 

The setup was easy. The filter pushes in without any complication and after pressing the on button, I turned the fan to ‘auto’ and waited to see what the purifier said about my air quality. 

Good news, I started in the green and within four hours of running the machine, the rating went lower in that category, thus improving my air quality. 

Then I put it to work in a house that has some verified air quality issues. As in, experts taking air samples found a sneaky mould problem. Bad for my buddies but great timing given my review of the Filtrete.

I watched as the numbers went up and up. From 20 to 40, 60 and eventually hitting just over 200, putting the air quality smack in the purple category. A reading under 50 is good but over 200 is the ‘severe’ poor-quality scenario. 

Within about four hours, the numbers went down dramatically into the green. I was sold and let them keep my machine and bought a new one for my home.

Some specs: 

My favourite features: It’s not noisy. There are several fan settings but it’s recommended you put it on auto, which I did. 

I operate the purifier by the buttons on the machine with a display that allows me to choose how long I want it to run, shows me filter life (by percentage) remaining, air quality level and a colour-coded snapshot.

I can use it without an app, though I can see that the app on this is cool. Not only does it give the same info you get from glancing at the machine but it collects air quality trends for those interested in that kind of data. It also means the ability to operate remotely.

The price. I don’t need anything fancy. This is more than enough to invest in some cleaner air.

My least favourite features:  I’d like it to be so small it fits into the palm of my hand. But I get that it cannot.

Reviewed by Shopping Essentials editor Leigh Taveroff.

This year-round air purifier that heats in winter and cools in summer has more bells and whistles than the Filtrete but they are legit and impressive. It will also cost you more. 

Dust, allergens and bacteria are just a few pollutants swirling around us at any given time while indoors. Cue allergic reactions, asthma, sneezing, coughing, watery eyes or just general lethargy.  

Out of sight out of mind may work for some, but not for me. I decided to try out Dyson’s Purifier Hot+Cool Formaldehyde HP09 purifying fan heater, which is said to sense, capture and trap pollutants for all-around cleaner air. This model has both a cooling and heating option which was a total bonus.

Summary: I love this machine for the peace of mind it gives when I study my clean air stats on the app. It’s an exceptional heater — much better than my old baseboard heaters and almost as good as my fireplace — even in a large room. The cooling feature isn’t effective enough to cool down a large space but is useful in a bathroom or small kitchen or bedroom.

About the Dyson Purifier Hot+Cool Formaldehyde HP09: Dyson claims this model removes 99.97 per cent of pollutants as small as 0.3 microns (an abbreviated term for “micrometre”, or a millionth of a metre — teeny tiny). 

Dyson works to continuously improve its products, and this is the latest technology in its purifier range. It uses a catalytic filter that can even detect and remove formaldehyde. This colourless chemical is often used in wood products and building materials, wallpaper, paints and can get trapped in our carpets and other household objects. When exposed to formaldehyde for prolonged periods of time, we can pick up a ton of short-term health problems like throat, nose and eye irritation or more serious health issues.

The HP909 provides warmed or cooled air that is 50 per cent cleaner, thanks to a HEPA filter that captures those teeny tiny particles and an activated carbon filter that eliminates both odours and gasses. The Air Multiplier technology purifies the entire room while regulating both air quality and temperature.

The HP09, like most Dyson products, is compatible with the Dyson Link app, so you can monitor your air quality stats in real-time.

The HP09 has 4.3/5 stars on dysoncanada.ca with 78 per cent of reviewers recommending the product to a friend. Reviewers with asthma and allergies say it promotes better sleep and helps them breathe easier. The most common concern amongst reviewers is around the cooling feature and the noise level in heating/cooling modes.

Specs and facts:

Weight: 5.7 kg Airflow at max. setting: 290 l/s Oscillation/Angle: 350 degrees Base diameter with plate: 248 mm Cord length: 1.8 m Number of speed settings: 10 HEPA filter: Glass HEPA Media Sound level: 62 decibel Height: 764 mm Length: 130 mm Width: 205 mm Warranty: Two-year warranty

Dyson machine testing methodology: Dyson machines are tested against a unique Point Loading Auto Response (POLAR) testing technique, that’s designed to mimic a real living space. Pollutants are introduced into the air and gradually removed. This testing method is different from the Clean Air Delivery Rate (CADR) method commonly used to test air purifiers across North America. The CADR test focuses on purifying the air in a confined space within set time periods, but this score alone does not take the full picture into account. The POLAR method ensures the air purifier is high performing and efficient — which I think is pretty cool. If you do too, you can read more about Dyson’s testing methodology here or watch the POLAR lab in action.

My favourite features: Hands-down my favourite is its ability to purify while heating my space. I’ve used it during fire season in B.C. and I notice a substantial difference in air quality. It’s great to have when cooking something oily or smoke-producing, to clear the air in the upstairs bedrooms quickly.

The heating feature was a happy surprise. It does a fabulous job of heating even large rooms in our home.

The app is a great feature too, to monitor the product’s effectiveness and see what may be floating around that we’re not aware of. Plus, you can turn on the heater before returning home to make sure the place is nice and toasty on arrival.

My least favourite features:  The cooling feature needs some work. It’s alright for a small space, but I found I needed to sit right in front of the fan in order to feel cooled down. Perhaps I need to tinker with the settings.

The price. There is no such thing as an ‘affordable Dyson’ but Dyson is known to have superior products for a reason, but it’s still hard to spend that kind of cash regardless.

Final thoughts: Excellent product and worth the price tag, especially if you have allergies or air quality concerns. The exceptional heater and ease of access with the app are awesome bonuses.

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