Do Air Purifiers Kill Viruses?

Little girl in bed with her teddy bear and coughing into her fist.

We’ve all learned just how fast viruses can spread. We know that they’re often transmitted in the air we breathe, so we take all of the lifestyle precautions to keep ourselves and our families well. 

So, what can you do to improve indoor air quality? And does something as simple as an air purifier really kill viruses?

Well, first, not all air purifiers kill viruses. But some of them have technology that can, and you don’t have to just trust us on that: there are large, dedicated groups of researchers who have confirmed the usefulness of air purifier technology to kill viruses. 

This article is an overview of that research and the types of air purifiers that can reduce the spread of airborne viruses, germs, bacteria, and other contaminants.

At Air Oasis, we believe that you as a consumer should feel empowered to find answers to important questions like this. That’s why so many of our resources don’t just offer information, but point you to reliable, in-depth, peer-reviewed research. We’ve dedicated our entire business to the pursuit of building world class air purifiers for the home, office, schools, and any other context where people want to breathe easier. We are a multigenerational, family owned and run business: read more about us here.

Air Purifiers & Viruses: Study 1

In the International Journal of Environmental Research and Public Health, a team of researchers published a study in 2021 called “Effects of Air Purifiers on the Spread of Simulated Respiratory Droplet Nuclei and Virus Aggregates.” The study performed a quantitative evaluation of the effect of air purifiers “on the spread of COVID-19,” simulating the effect by spraying respiratory droplet nuclei through a mesh nebulizer. They then measured the change in particle number concentration in the test chamber, using a HEPA filter air purifier. The air purifier was continuously operated.

It’s important to note that this study was conducted with the aim of addressing the position that air purifiers could actually recirculate respiratory droplets, if they’re located near the exhaust section of the air purifier. These were their findings: 

“These observations indicated that the airflow generated by the air purifier can spread respiratory droplet nuclei when the source is close to the exhaust of the air purifier. However, in comparison with the number concentration without the air purifier, the number concentration was lower after 2 min of operation of the air purifier, even with the source located near the exhaust. Without the air purifier, the simulated respiratory droplet nuclei accumulated in the chamber and, therefore, the concentration continued to increase. However, continuous operation of the air purifier removed simulated respiratory droplet nuclei, because the air was recirculated and the air purifier contained an H13 HEPA filter with a removal efficiency of 99.99% for particles in the size range of the respiratory droplet nuclei.”

Takeaway: there is very minimal risk that the exhaust portion of an air purifier will recirculate particulates containing a virus, and even if it does, it still diminishes the concentration of contaminants in the air.

Portable Air Cleaners and Viruses: Study 2

A second study, also published in 2021, can be found in the Elsevier Public Health Emergency Collection and is titled “Are the Portable Air Cleaners (PAC) really effective to terminate airborne SARS-CoV-2?” The study addresses the discussion of using HEPA air filters (in this study termed “portable air cleaners”) to reduce transmission of the SARS-CoV-2 virus. 

This study evaluated the air and surfaces for contamination, collecting 29 total samples across nine households. 75% of collected samples were positive for SARS-CoV-2. After use of the portable air cleaner, all but one were negative. 

Their conclusion was as follows:

“[I]t has been demonstrated that PACs with HEPA filters reduce aerosol concentration and accelerate their removal in rooms with low ventilation rates.”

There is an important caveat to their findings, expressed here:

“It is worth highlighting that the PAC was not effective in room C, with a size larger than the recommended by the device (27 m2), although the operating time was longer than in other rooms (>2 h). However, in the room of the patient E, whose size was in the recommended limit, the concentration of particles in the air reduced after 2 h of cleaning, and the result from real-time RT-PCR analysis was negative. These facts show the importance of following the manufacturer's recommendations, using as many devices as necessary, according to their filtration capacity and the size of the room.”

Put plainly, the takeaway is that the air purifier killed the virus, but only when it was used as designed, in the right size space and according to manufacturer specifications.

Should People Purchase Air Purifiers to Kill Viruses? Study 3

A last study we will summarize was published in the Morbidity and Mortality Weekly Report, republished by the National Institutes of Health. It is titled, “Efficacy of Portable Air Cleaners and Masking for Reducing Indoor Exposure to Simulated Exhaled SARS-CoV-2 Aerosols.” A team of researchers set out to review the capabilities of air purifiers to reduce airborne transmission of the SARS-CoV-2 virus, and investigate the key Centers for Disease Control (CDC) recommendations, which include supplementing ventilation systems with portable HEPA air cleaners.

The team simulated transmission between an infected person with COVID-19 and uninfected persons in a closed indoor space. They found the following:

“The addition of two HEPA air cleaners that met the Environmental Protection Agency (EPA)-recommended clean air delivery rate (CADR) (5) reduced overall exposure to simulated exhaled aerosol particles by up to 65% without universal masking. Without the HEPA air cleaners, universal masking reduced the combined mean aerosol concentration by 72%. The combination of the two HEPA air cleaners and universal masking reduced overall exposure by up to 90%. The HEPA air cleaners were most effective when they were close to the aerosol source. These findings suggest that portable HEPA air cleaners can reduce exposure to SARS-CoV-2 aerosols in indoor environments, with greater reductions in exposure occurring when used in combination with universal masking.”

What Air Purifiers Kill Viruses?

These studies were rigorously conducted according to sound scientific principles, or represent the educated opinion of analysts who reviewed such studies. It’s the kind of information you can reasonably trust and use to make your own informed decisions about how to protect your family against the spread of any virus, including COVID-19.

The type of air purifier technology mentioned most in these studies is HEPA, which is a core approach to purifying the air. There are additional technologies, and we’ve found that multistage filtration is the best and most effective way to fully clean indoor air. Coupled with UV, carbon filtration, and bi-polar ionization, you have a winning combination to safeguard against viruses.

To buy an air purifier to kill viruses in your home, we recommend you check out the iAdaptAir® HEPA UV Air Purifier, our bestselling, best-in-class air purifier for protection from viruses and all types of irritants and contaminants.

Up next, read an overview of the Best Air Purifiers for COVID-19.

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