CLEVELAND, Ohio — An air purifier can remove dust and mold from the air. But does it clean the air of COVID-19?

Experts say yes. And while no purifier can protect you completely from the coronavirus, with a HEPA filter it can be beneficial in small rooms.

“What I’ve seen is that it’s estimated that it can take out somewhere in the 90th percentile of COVID from the air, and if it’s continuously run, up to 99% or more of the COVID in the air,” said Scott Frank, director of public health initiatives for the Department of Population and Quantitative Health Sciences at Case Western Reserve University.

With the weather growing chillier, people will be indoors more, where air particles and droplets carrying the novel coronavirus can be suspended.

Air purifiers can run over $1,000, and they can cover upwards of 1,000 square feet.

For bigger buildings and schools, having a good HVAC system could be a better option for practical and financial reasons. But, for example, Cleveland Heights High School is 362,000 square feet, and the Halle Building has 383,000 square feet. Schools would need purifiers in every classroom, and offices in big buildings would need their own purifiers.

Here’s what you need to know about purifiers, including links at the bottom for purifiers starting at $54.99.

How they work

Portable air purifiers help clean the air by removing particles such as dust, pollen, germs and smoke.

A purifier has a fan inside, which pulls in air into grill slots, said Richard Corsi, an indoor air quality expert and dean of the Maseeh College of Engineering and Computer Science at Portland State University.

Corsi said purifiers usually have a pre-filter to help protect the high efficiency particulate air (HEPA) filter from large particles such as cat hair or large pollen and dust particles. The large particles are removed in the pre-filter and won’t affect the HEPA filter.

“And then the HEPA filter comes after the pre-filter,” Corsi said. “And all of that air is sucked in through a fan. And the fans in portable air cleaners should be, and I think almost always are, designed so that they can handle the pressure drop that is required to sort of suck air through those filters. So it’s not going to burn up on you at any time.”

What to look for

HEPA filters are best, and make sure to buy a purifier that can accommodate your room. If a purifier will be in a room that’s 600 square feet, it’s necessary to buy one that covers that much square footage.

You want the air purifier to effectively change an area’s air exchange rate, and 3.5-4 air changes an hour is good, Corsi said.

The Clean Air Delivery Rate, referring to how quickly the purifier can clean smoke, dust and pollen, is important to look at as well, and Corsi said 300 standard cubic feet per minute is high and to focus on the smoke rate.

“For a HEPA filter, those three values are actually pretty close to one another, but I would focus on the smoke one because that will be the limiting factor,” Corsi said.

How to use a purifier

Corsi also said it’s important to run purifiers on the maximum setting to be most effective. He said if you don’t hear noise from your purifier, then it’s probably not working as it should.

Dr. Marie Budev, the medical director of the lung transplant program at Cleveland Clinic, said when positioning the purifier in a classroom for example, students shouldn’t be sitting in the stream of air that’s coming out of the purifier. Budev said she thinks the purifier can work anywhere properly in a classroom, but it’s very important to make sure students are safe with regards to social distancing and masking.

Should you have one at home?

Budev said the safest place for people during the pandemic is their home.

“The average person probably does not need an air purifier,” Budev said. “But if you’re going out, and you are not masking and you are not practicing good social distancing practices, this (a purifier) is something to consider. But if you are doing all those things, you really don’t need an air purifier in your home.”

Budev said having a purifier could be beneficial if someone in the home is infected with COVID-19 or needs to quarantine. The purifier can be put in the person’s room with the door closed to protect others, Budev said.

Budev has a purifier to help remove dust and dander from her two cats. Still, the purifier can only remove particles that are in the air; it can’t clean particles that are already in the floor or furniture, Budev said.

Air purifiers only reduce risk — not eliminate it

While air purifiers could help, they should not be perceived as the sole means of battling COVID-19.

Frank, Corsi and Budev all acknowledged people could feel a false sense of security in having an air purifier. They all said people should still wear masks and keep their distance.

As the pandemic continues and cases rise, everyone must be vigilant.

“This is part of the plan, and maybe a small part of the plan in trying to fight COVID and trying to stay safe, but it is not the plan,” Budev said of air purifiers. “So we have to make very clear to our readers and to people out there that this is just one part of what you could do. But still the other things are more important.”

When to go for HVAC upgrades instead

When it comes to upgrading an HVAC system, Corsi said it’s important to connect with a mechanical contractor to discuss what may need to be done.

“It may mean increasing the motor, size of the motor,” Corsi said. “So there’s a lot of things that go into pressure drop through a system, and that’s where it gets complicated. And every system is so different, so you really need to have a mechanical contractor that can come in and do flow testing on the system and look at the motor you have and all those kinds of things. There’s not sort of one magic answer to that.”

Minimum Efficiency Reporting Value (MERV) filters are used in HVAC systems, and ones that are MERV-13 or higher can capture small particles, including ones from viruses, according to the Environmental Protection Agency.

The higher the rating is for the MERV filter, the better it is at pulling in different kinds of particles, according to the EPA. Frank said it’s very important that air is vented outside and not re-circulated indoors.

Corsi said having an HVAC system that could handle a MERV-13 filter would be ideal, but some systems can’t use those kind of filters because of factors such as motor size.

Most systems can handle MERV-11 filters, and they can still lower air particle concentration, Corsi said.

“A MERV-13 filter will, if it’s seated properly, if the person who’s putting the filter in place knows what they’re doing, the filter will remove particles that are definitely the size of the particles that convey this coronavirus,” Corsi said. “It can be very, very effective at not completely eliminating — nothing completely eliminates, but dramatically reducing the particle levels in the air.”

Air purifiers you can buy

$54.99 at Bed Bath & Beyond: The Therapure 360 HEPA compact air purifier comes with a HEPA filter. It can only cover up to 41 square feet, so it could be used in a bathroom or other small spaces.

$159.99 at Best Buy: The Honeywell InsightTM has a HEPA filter, and it can cover a room of up to 175 square feet. This purifier can clean a room’s air up to five times an hour.

$199.99 at Best Buy: The Levoit Tower Air Purifier is in black and has a HEPA filter. It can cover a room up to 538 square feet, and a light also comes on to let you know when the filter needs to be changed.

$219.00 at Home Depot: The Winix D480 air purifier has a HEPA filter, and it has a washable pre-filter that helps capture pet hair and bigger airborne particles. The purifier can cover a room up to 480 square feet.

$249.99 at Amazon: The Honeywell True HEPA allergen air purifier is in white, and it can produce five air changes an hour in a 465 square foot room.

$265.93 at Amazon: The AeraMax 300 Large Room Air Purifier comes with a HEPA filter, and it helps trap mold, dust, germs and smoke. It can cover rooms from 300-600 square feet.