anything less than MERV 12 captures less than 4% of the particulate matter in the air...most stuff in the air is less than 1 micron in size (1/25400 of an inch ) that will go through ANY pleated filter or ANY "filter" for that matter....certainly stepping down in the MERV rating wont help. IF you have asthma or allergies and you don't go with a EAC that you understand how to maintance properly, your only hurting yourself and your family
All I know is the dust levels dropped dramatically even with a Merv 7 4" filter. Small particulates tend to attach to larger particles due to static electricity.
anything less than MERV 12 captures less than 4% of the particulate matter in the air...
Perhaps by count but not by weight. Allergies are dose-responsive, i.e. it works by weight. Particle weight increases as the cube of its size. I love high MERV filters but you're getting less improvement in captured particle weight out of the air with each increase in MERV rating (i.e., from 7 to 8 will likely be a greater improvement than 13 to 14). The reason you should use high MERV filters is not the % captured. It's that particles that penetrate the deepest into our bodies are the smallest. Coarse particles are rejected easily by our respiratory system.