What does my ventilation system filter remove

The Microparticle Performance Rating (MPR) measures only very small particles (between 0.3 and 1 microns). Ratings on the MPR scale range from 0-2200. The higher the number, the smaller the particles that are filtered.

To give you an idea of the size particles we are talking about, mold spores and pollen are usually in the 10-30 micron range, bacteria 2-3 micron, and tobacco smoke 0.5 micron. Here are some general guidelines to consider when choosing an air filter for your HVAC system: