When used correctly, air and HVAC filters can help reduce airborne contaminants, including viruses, in a small building or space. By itself, cleaning or filtering the air is not enough to protect people from COVID-19. Canadian public health guidelines related to COVID-19 have evolved as our understanding of the virus improves. We continually review tests as they occur and work with our partners across the country and around the world to ensure that we integrate the most current and highest quality information into our guide. Appliances that use HEPA filters only work when turned on, so you may need to run your oven fan continuously or for longer periods of time.
When used together, air filters and hepa masks reduced exposure to respiratory aerosols by up to 90%.
Air purifierswith HEPA filtration efficiently capture particles the size (and much smaller than) the virus that causes COVID-19, so the answer is yes. Use the highest-efficiency particulate filter that the forced air system is able to handle, without impeding airflows. Coronavirus is at the lower end of the range of a HEPA filter, so it may not be 100% effective in a single pass.
As the name suggests, these filters are very good for taking things out of the air and holding them so they can't circulate again. Upgrading to a filter with a higher MERV rating can help reduce the amount of small particles in the air. Researchers have evaluated the ability of air filters to remove inactive particles in carefully controlled environments, but they don't know how they would work in a real world environment. In one study, the use of HEPA air purifiers in a conference room significantly reduced the exposure of nearby participants and a speaker to airborne particles produced by a simulated infected participant.
This NASA study of HEPA filtration is quite technical, but it explains why HEPA filters are actually almost 100% more efficient at 0.01 microns at capturing ultrafine particles below the HEPA test standard of 0.3 microns. The most critical particle size (MPPS) for each filter is in a window ranging from 0.12 to 0.25 microns. David Fisman, MD, an epidemiologist at the University of Toronto, Canada, who was not involved in the research, said in an article for Nature: This study suggests that HEPA air purifiers, which remain underused in Canadian hospitals, are an inexpensive and easy way to reduce the risk of airborne pathogens. The combination of two HEPA air filters and universal masking reduced total exposure by up to 90%. These findings suggest that portable HEPA air purifiers may reduce exposure to SARS-CoV-2 aerosols indoors, and that greater reductions in exposure occur when used in combination with universal masking.