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Environmental Health Division
Last Updated: 10/03/2022
Ventilation and Filtration
Pollutant Prevention/Source Control
Eliminating or controlling pollutant sources is the first step in reducing your exposure to pollutants. Adequately ventilate the areas that have pollutant sources. Consider filtration as a final step in reducing the pollutants in your home.
Common household sources of pollutants:
- Particulates: Come from things that burn, like candles, incense, smoking, fires and/or wood smoke.
- Volatile Organic Compounds (VOC's): Scented products like candles, incense, air fresheners, perfumes and scented cleaning products. Use low or no-VOC paints, varnishes and hobby supplies.
- Pets: If allergies are a problem, consider pets without fur or if you already have a pet, at a minimum, keep them out of the bedroom.
- Chemicals: Store chemicals safely and according to the manufacturers' suggestions.
- Vacuum Cleaner: Regularly change bag or empty canister. Choose vacuum cleaners that have filtration built into their exhausts.
- Use cleaners that are water-based or low in VOC's and do not contain hazardous chemicals. Buy and store only what you need.
Whole House Filtration
A filtration system that is incorporated into your furnace or designed/installed to collect and distribute air to the whole house.
- Minimum Efficiency Reporting Value (MERV) Rating: MERV ratings can be used to compare filters to each other. The MERV rating is the amount of filtration that a filter can accomplish at a given airflow. A higher MERV rating results in a greater reduction in pollutants, therefore cleaner air leaving the filter. The MERV ratings have a range from 1-20.
Portable Air Cleaners
A filtration system that is designed to collect and distribute air in only one room at time.
- Clean Air Delivery Rate (CADR) Rating: CADR is a measure of a portable air cleaner's delivery of contaminant free air. The value is in cubic feet per minute, which is the amount of 12"x12"x12" boxes of air that are cleaned per minute.
One way to measure how much fresh air is coming into a room is to measure carbon dioxide. For more information see:
Other Filtration Terms
- High Efficiency Particulate Air (HEPA) Filter: A HEPA filter removes 99.97% of particles at 0.3 microns. HEPA filters have a MERV rating of 17-20.
- Ultraviolet Germicidal Irradiation (UVGI): These devices use ultraviolet (UV) lamps to generate ultraviolet radiation that is intended to destroy/kill biological pollutants.
- Ozone: Ozone is a lung irritant that can cause adverse health effects therefore ozone generating air cleaners are not always safe and effective in reducing indoor air pollutants.