Between COVID-19 and the alarming occurrence of forest fires, among the things we have learned is to not take the air we breathe for granted. While we can’t control what may be in the air outside, many homeowners have been paying more attention to their indoor air quality. As a result, there have been many questions about residential air filters, and how effective they might be. Among the most reliable types are those that are defined as meeting the standard for “high efficiency particulate air”, also known as HEPA. However, filtering is only half the challenge. Your HVAC system needs to send a certain volume of air through a HEPA filter to meet a clean air delivery rate (CADR). Look for a CADR of at least two-thirds of the room’s area (e.g., 120 square feet would need a CADR of at least 80).

The bigger your home, the greater the fan capacity required to circulate indoor air through your filters adequately. Furthermore, many homeowners choose additional and more focused air cleaning by installing “air purifiers” in specific rooms. Although they don’t really “purify”, they do clean the air to a particular standard, if they are designed to serve the room size with an effective CADR.

The bottom line: You need to establish what your needs are to know which unit(s) will effectively do the job of filtering out allergens like dust and dander, as well as bacteria and other contaminants.