simpson33 via iStock/Getty Images Plus

The smoke from Canadian wildfires has deteriorated the air quality across the U.S., negatively impacting the lives of millions of Americans. As we woke up to another day with veils of smoke blurring the distance, I rearranged my own air purifiers at home to get the most out of them. 

If you're shopping for air purifiers for your home, there are several factors to consider when choosing and setting up an air purifier in a room, whether it's to reduce smoke pollution, lower the risk of viral transmission, or improve seasonal allergies.

Recommends:The best smart air purifiers to keep your home's air clean

It's essential to consider the type of filter, cost, user experience, size of the room or space where the air purifier will go, the price of the unit, and the ease of maintenance -- as well as the follow-up costs for replacement filters. Choosing the right features is paramount for a device that will process the air you'll breathe into your lungs, so we'll rank them in order of importance. 

1. The type of filtration, including the stages

Ivan Balvan via iStock / Getty Images Plus

Many air purifiers tout fancy filtration systems to remove the most air particles. You only need to look for one with a true HEPA filter, which stands for High-Efficiency Particulate Air filter, as these capture 99.97% of particles that are 0.3 microns in diameter. Everything else is frosting.

Avoid:I'd caution you against buying air purifiers that use UV or ionization as these produce ozone, a lung irritant proven to decrease lung function and inflame lung tissue.

Stages are popular in air purifying systems. The stages are the layers of filtration the air goes through in the air purifier during cleaning. These devices typically have at least a washable fabric filter, then the replaceable filter, which is the one that should always be a HEPA filter. Thiswould be a two-stage system. Some systems have three stages, where the third layer is an activated carbon filter that removes odors and gases from the air. 

2. The size of the room you're purifying

Maria Diaz/

First, measure the size of your room. 

Air purifiers are optimized to clean specific-sized rooms, as their power is measured by how often they can exchange all the air in the room, called Air Changes per Hour (ACH). The higher the ACH, the more powerful the air purifier. An ACH of 4 means it can exchange all the air in the room four times in one hour, so it can clean the air in the room in only 15 minutes. The CDC recently rolled out new guidelines recommending five air changes per hour to reduce airborne virus transmission. 

Also: This $100 smart fan is powerful enough to cool your whole room

For example, the Levoit Vital 200S air purifier can clean the air in a 380-square-foot room (think 20ft by 19ft) in just 12 minutes. That's an ACH of 5. It can still be used in larger rooms but its ACH rate will decrease for larger rooms. 

3. Cost, including maintenance

onurdongel via Getty Images

Cost is another critical factor when choosing an air purifier. You can find the aforementionedLevoit Vital 200S , priced at$190, as easily as you can find a$750 one fromRabbit Air A3 , so choosing wisely is important. 

After you factor in the room size for your air purifier and the initial budget, you need to consider maintenance costs and factor that into your long-term budget. Air purifiers need filter replacements every few months -- whether every three, six, or 12 months will depend on the filter and the use. 

Also: I'm letting AI mop my floors now, and I'm not going back

Some air cleaners have a lower upfront cost but require frequent and more expensive filter replacements, so check how often filters need to be replaced and how much they cost before settling on a model. You can also check the product reviews to see if there are often issues with delays and stock.

4. Noise level, depending on where you put it

d3sign via Getty Images

I don't mind the hum of an air purifier by my bed -- it serves as a source of white noise to lull me to sleep with clean, fresh air. But I don't always want to hear the fan when I'm working and need to focus while my dog is in the office, triggering my allergies, so I know I need a quiet one in that room. 

Noise level is typically listed on the air purifier's specifications chart, so take a gander at it if you're sensitive to noise or looking for a quiet device. 

Also:The best robot vacuum: Roomba, Roborock, and DreameBot models compared

There are a lot of whisper-quiet air purifiers on the market, ranging from 24-30 decibels. For reference, the hum of a refrigerator is around 40 dB, and a vacuum cleaner ranges from about 60-70 dB.

5. Extra and smart features

ArtistGNDphotography via iStock/Getty Images Plus

I enjoy smart features in almost any home device. My smart air purifiers feature integrations with Alexa, so I can ask my Echo speakers to turn them on or off, control them as part of 'goodnight' routines, and I can easily control them from mobile apps on my phone. 

Also:Smart home starter pack: 5 devices that will make your life easier

Other extra features include air quality indicators, schedules, timers, and filter change indicators. These features add convenience to the consumer, but they could add to the initial cost of the device, so consider which are worth the expense for you. 

FAQ

Does an air purifier help with wildfire smoke?

Yes, air purifiers can help with wildfire smoke, but only when used correctly. Air purifiers provide filtration for enclosed spaces by removing fine particles in the air, including those in smoke. 

Also: The smart air purifier that saved our holiday plans

These portable air cleaners can remove wildfire smoke from indoor air as long as the following conditions are met:

• The doors and windows remain closed
• The air purifier can exchange the air in the entire room
• The air cleaner uses a HEPA filter
• The air purifier is properly maintained (the filter is clean and doesn't need replacing)

If you're concerned about wildfire smoke and have sensitive population members at home, you can also use a high-quality air filter in your home's HVAC system.

How do air purifiers work?

An air purifier is a filtration system for the air in an enclosed space. It's an enclosure with a fan inside to pull the air from one side and push it out the other. As the air is pulled in, it's pushed through layers of filters to remove the fine particles from it and the clean air is released on the other side. 

Is there a downside to air purifiers?

Aside from the monetary investment and the minor energy consumption, there isn't a real downside to an air purifier with a HEPA filter. 

Some air purifiers use UV and ionization to neutralize air particles but produce ozone as a byproduct of their operation, which can cause lung irritation, coughing and even lead to permanent lung damage. 

This is why it's best to choose air filtration systems with HEPA filters, as these trap the fine particles in the air without producing gases.

Recommends

The 5 best VPN services (and tips to choose the right one for you)The best AI art generators: DALL-E 2 and other fun alternatives to tryThe best Android phones you can buy (including a surprise pick)The best robot vacuum and mop combos (and if they're worth the money)

• The 5 best VPN services (and tips to choose the right one for you)
• The best AI art generators: DALL-E 2 and other fun alternatives to try
• The best Android phones you can buy (including a surprise pick)
• The best robot vacuum and mop combos (and if they're worth the money)