When selecting a portable air cleaner, furnace filter, or HVAC filter, keep in mind: No air cleaner or filter will eliminate all of the air pollutants in your home. Note that most filters are designed to filter either particles or gases. So in order to filter both particles and gases, many air cleaners contain two filters, one for particles and another for gases (in some cases including gases that have odors). Other air cleaners only have one filter, usually for particles. In addition, some air cleaners or filters are targeted to specific types of gases or VOCs. Consult the specific product packaging or labeling for more information. All filters need regular replacement. If a filter is dirty and overloaded, it won’t work well.
PORTABLE AIR CLEANERS
To filter particles, choose a portable air cleaner that has a clean air delivery rate (CADR) that is large enough for the size of the room or area in which you will use it. The higher the CADR, the more particles the air cleaner can filter and the larger the area it can serve. Most air cleaner packaging will tell you the largest size area or room it should be used in. Portable air cleaners often achieve a high CADR by using a high-efficiency particulate air (HEPA) filter.
To filter gases, choose a portable air cleaner with an activated carbon filter or other
filter designed to remove gases. Note that there are no widely used performance rating systems for
portable air cleaners or filters designed to remove gases. The CADR rating system is for particles only. Activated carbon filters can be effective, provided that there is a large amount of material used in the filter.
A portable air cleaner with a high CADR and an activated carbon filter can filter both particles and gases.
Generally speaking, higher fan speeds and longer run times will increase the amount of air filtered. An air cleaner will filter less air if it is set at a lower speed. More air will pass through the filter at higher fan speeds, so typically filtration will be greater at higher fan speeds. Increasing the amount of time an air cleaner runs will also increase air filtration.
Note this chart is for estimation purposes. The CADRs are calculated based on an 8-foot ceiling. If you have higher ceilings, you may want to select a portable air cleaner with a higher CADR.
FURNACE AND HVAC SYSTEM FILTERS
Furnace and HVAC filters work to filter the air only when the system is operating. In most cases, HVAC systems run only when heating or cooling is needed (usually less than 25% of the time during heating and cooling seasons). In order to get more filtration, the system would have to run for longer periods. This may not be desirable or practical in many cases since longer run times increase electricity costs and may also result in less reliable humidity control during the cooling season. Furnace and HVAC filters for homes are usually designed to filter particles. If you decide to upgrade or use a higher efficiency filter, choose a filter with at least a Minimum Efficiency Reporting Value (MERV) 13 rating, or as high a rating as your system fan and filter slot can accommodate. You may need to consult a professional HVAC technician to determine the highest efficiency filter that will work best for your system. Other devices that do not have filters may also remove particles and gases. They usually fit inside the HVAC ductwork and are more common in large and commercial buildings. See the EPA technical document, Residential Air Cleaners, 3rd edition, for more information: www.epa.gov/indoor-air-quality-iaq/ residential-air-cleaners-second-edition-summary- available-information. EPA does not certify or recommend specific brands or models of air filters or portable air cleaners.