Guest blog by Kathleen Owen, ASHRAE Fellow, ETF member and Air Pollution Control Engineer for Owen Air Filtration Consulting

Have you been asked how MERV filters catch PM2.5?  Obviously, it’s easy to go to the ASHRAE Standard 52.2 MERV table and see that a MERV 13 filter is ≥ 85% in the 1-3 µm particle diameter size range.  This is often the answer you need.  Still the questions keep coming, including from ASHRAE SSPCs 62.1 and 62.2.  With ISO 16890 providing an ePM and these ASHRAE committees deciding to specify filters using particulate matter efficiencies, it became clear that ASHRAE 52.2 needed to address this issue.