When used correctly, air purifiers can be a great help in reducing pollutants, including viruses, in the home or in confined spaces. However, on its own, a portable air purifier is not enough to protect people from COVID-19. High-efficiency particulate air (HEPA) filters are designed to filter out contaminants from the air that passes through them. Research at a hospital flooded by people with COVID-19 has confirmed that portable air filters effectively remove SARS-CoV-2 particles from the air, the first such evidence in a real environment. Questions have been raised as to whether DIY air filters can be effective in reducing virus particles in indoor environments.
HVAC systems in large buildings typically filter air before it is distributed throughout the building, so consider upgrading HVAC filters as appropriate for your specific building and HVAC system (consult an HVAC professional). Portable air purifiers (also known as air purifiers) can be particularly useful when additional ventilation with outdoor air is not possible without compromising indoor comfort (temperature or humidity) or when outdoor air pollution is high. In the general room, the team found SARS-CoV-2 particles in the air when the filter was turned off, but not when it was turned on. Many manufacturers use the Clean Air Supply Rate (CADR) rating system to evaluate air filter performance.
Using air filters alone cannot guarantee adequate air quality, especially when there are significant sources of pollutants and insufficient ventilation. The results suggest that air filters could be used to reduce the risk of patients and medical staff contracting SARS-CoV-2 in hospitals, the study authors say. The filters are designed to improve indoor air quality by physically removing small particles of matter that may be floating, such as dust, pollen and pet dander. The EPA does not recommend the routine use of DIY air purifiers as a permanent alternative to products of known performance (such as commercially available portable air purifiers).
Hospitals have turned to portable air filters as an attractive solution when their isolation facilities are full, but it's important to know if such filters are effective or if they simply provide a false sense of security. These findings suggest that the use of portable HEPA air filters and universal masking may reduce exposure to simulated SARS-CoV-2 aerosols indoors, and that greater reductions occur when air filters and masking are used together. The researchers collected air samples from the rooms for a week when the air filters were on and two weeks when they were turned off. DIY air purifiers can provide some benefits for reducing concentrations of viruses and other indoor air pollutants, but research is limited and there are several important considerations explained below.