How well your central heating and cooling system cleans the air largely depends on the quality of your air conditioner filters.
Filters are rated from 1 to 16 on the Minimum Efficiency Reporting Value scale. The MERV scale is based on the percentage of particles, from 0.3 to 10 microns in size, that the filter catches. The higher the MERV number, the better it filters the air.
The Microparticle Performance Rating measures 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 a filter removes.
Mold spores and pollen are usually in the 10-30 micron range; bacteria, 2-3 micron; and tobacco smoke, 0.5 micron.
Understanding the MERV Scale
Here are some guidelines to consider when choosing air conditioner filters:
- MERV 1-4 Air Filters: These inexpensive fiberglass mesh filters only remove particles over 10 microns in size. They do little to improve the indoor air quality in your home.
- 5-8 Air Filters: These medium-quality pleated air filters can remove particles down