• Joe Xie

Air Purifiers and Indoor Air Quality

Updated: Sep 14, 2020

Many retailers are now reporting high demand for air purifiers, both due to COVID-19 as well as the many wildfires currently raging across western states.


What should you consider when you are purchasing an air purifier?

  • Ensure the purifier has a true HEPA (high-efficiency particulate air) filter

  • Ensure it has an activated carbon pre-filter

  • Ensure the purifier does not have an "ion generating" or "ionic purification" feature

HEPA filtration will help reduce PM2.5 (particulates with aerodynamic diameters of around 2.5 microns) as well as ultrafine particulates (particulates with aerodynamic diameters of less than 0.1 microns) in an enclosed space. There are currently no regulations on ultrafine particulates, although recent research has shown that they may be quite damaging to our health due to their ability to easily pass into our blood stream through our lungs and reach our major organs.


There is currently no peer-reviewed scientific studies on whether floor air purifiers can help reduce our exposure to SARS-CoV-2; although theoretically, true HEPA filters should have the ability to filter out some viral particles in the air due to their filtration efficiency. I would not recommend people to rely solely on HEPA air purifiers to prevent their exposure to SARS-CoV-2; social distancing and mask wearing remain the most effective ways to reduce exposure.


Activated carbon pre-filters are helpful in eliminating nuisance odors that are organic in nature, which will help make indoor environments more pleasant.


Those air purifiers that are marketed as having some kind of "ion purification" stage can generate ozone, which is an air pollutant. In a room with stagnant air, ozone can build up easily and reach concentrations that are harmful to your health. There are some manufacturers claiming their ion purifiers do not generate any ozone; I would evaluate their claims carefully before deciding on a purchase.