More people than ever before are considering room air filters and purifiers to protect themselves against COVID-19 indoors. But do these devices really make a difference?

Air purifiers and filters can help reduce airborne contaminants, including viruses, in a home, office or other confined space. While an air purifier by itself is not enough to protect people from COVID-19, according to the Centers for Disease Control and Prevention (CDC), when used along with the other best practices it recommends, operating an air purifier can be part of a plan to protect you and your family.

It’s easy to see how breathing cleaner air could improve overall health and wellbeing – and some independent studies do show a benefit from air filters and purifiers. In fact, some of the technologies now used in these devices have been scientifically proven to remove or destroy harmful pathogens in the air.

Air purifiers and filters can help reduce airborne contaminants—including viruses — in a home, office or other confined space.

Types of air cleaners

Before you buy, learn about the three primary types of air cleaning technologies:

• HEPA (high efficiency particulate air) filters use a woven filtration material to trap particles like smoke, dust and pathogens. Certified HEPA filters can collect 99.97% of particles of a certain size (0.3 microns in diameter or larger), which includes many viruses. Filters need to be changed on a regular basis and can be costly, so check the price before you buy. While HEPA filters capture the most contaminants, they can also impede the volume of air that circulates.
• Ultraviolet germicidal irradiation, (UV-GI) also referred to as UV-C, uses a specific type of ultraviolet light that deactivates pathogens such as bacteria and viruses. It’s a technology that’s been tested and used in hospitals and healthcare settings for years. A UV-C purifier doesn’t just trap smoke and dust like a HEPA filter; instead, it inactivates viruses and other pathogens, rendering them harmless. While direct exposure to UV-C light can be harmful, it is safe when the UV-C bulb is completely concealed inside the unit, shielded from sight. For the most effective results, it’s important that the UV-C light is strong enough and the air exposure time is long enough. The Airetrex 365 uses a 5-watt UV-C bulb for powerful exposure, with an air replacement rate of up to four times per hour in a 10’x10’ room. With normal use, the bulb lasts up to two years. More details about UV-C technology from independent experts can be found on our Why UV-C page.
• Ionization uses electricity to change airborne particles from a positive to a negative state, weighing them down and causing them to drop from the air – effectively deactivating the virus particles. However, in the process, a potentially harmful byproduct called ozone is created. Anyone considering this technology should check the Ozone Parts Per Million rating (PPM) to ensure it is below the Food and Drug Administration’s limit of .005 PPM.

Can you combine technologies?

What about filters and purifiers that combine multiple technologies that use HEPA, UV-C or ionization together? Would that produce even cleaner air? The findings here are still unclear, and more is not always better.

It’s best to focus on the features and benefits most important to you – and how well different filtration components can meet those needs in your selected space. For example, if you only want to trap most large airborne particles and allergens, a HEPA filter might be sufficient. On the other hand, if you’re concerned about viruses, like the coronavirus that causes COVID-19, you might consider the more advanced features of an air purifier with a UV-C light.

Other considerations

You should also consider room size before deciding on which air cleaner to purchase. Most manufacturers specify a maximum square footage for different models, according to their capacity to filter the air in a room of a particular size in an hour. For homes, most heating and air conditioning experts recommend that the air in a room be replaced or exchanged close to three times every hour at minimum.

Air purifiers work much better in a closed or sealed room versus a big open space. Most homes rely on natural ventilation from doors and windows for fresh air, unless the home has an air exchanger. Air purifiers can be particularly effective in homes and places with limited ability to add fresh air.

Which filter works best

The answer depends on your needs. But the good news is that we can all breathe a little easier with today’s advances in home air cleaning technology.

People with a condition like asthma will benefit most from HEPA air filters since they remove irritants like smoke, dust and dander. All of these elements can impact health. If you’re looking for a purifier to potentially reduce exposure to pathogens and viruses, an air purifier with UV-C technology will likely process and sanitize more air in less time.