When it comes to HVAC design, MERV-13 is the minimum filter rating we recommend. This rating ensures that at least 90% of particles in the 3-10 µm range, 85% of particles in the 1-3 µm range, and 50% of particles in the 0.3-1 µm range are removed. ASHRAE recommends a filter with a minimum MERV rating of 13, but MERV 14 or higher is preferred. MERV 14 and higher can capture particles that are even smaller than previous MERV ratings, ranging from 0.3 to 1.0 microns in size. In light of the COVID-19 pandemic, there is no standard recommended MERV rating for reopening.
However, ASHRAE recommends a MERV rating of 13+ to capture 1 micron sized particles that would be effective for capturing COVID-19 virus particles indoors.
