Air Cleaners and Filters: What EPA Says They Can and Cannot Do

An air cleaner is a supplement, not a substitute for dealing with where the pollution comes from.

EPA says the most effective ways to improve indoor air are source control and ventilation, and that filtration can help when those are not enough. It also says no air cleaner or filter will eliminate all of the pollutants in a home, and that most devices target either particles or gases, not both (EPA). For the bigger picture, see indoor air quality services.

A portable air cleaner filters the air in one room or area. A central furnace or HVAC filter is meant to filter the air throughout a home (EPA).

• Particles. EPA says to choose a unit with a clean air delivery rate (CADR) large enough for the room. A higher CADR means more particles removed and a larger area served (EPA).
• Room size. EPA gives a chart based on an 8-foot ceiling. Higher ceilings call for a higher CADR, and in an open floor plan you should consider the whole open area (EPA).
• Gases. Units with activated carbon filters can address gases, but EPA notes there is no widely used rating system for gas removal, and that it has not found plasma, photocatalytic oxidation or UV light to be effective at removing gases in portable residential units (EPA).
• Run time. Higher fan speeds and longer run times filter more air (EPA).
• Placement. Put the unit where you spend the most time and keep the airflow unobstructed (EPA).

EPA also says the ENERGY STAR label reflects energy efficiency only, not how well a unit cleans the air, and that EPA neither certifies nor recommends particular brands (EPA).

EPA says these filters work only while the system is running, which is often less than a quarter of the heating and cooling seasons. It suggests a filter rated at least MERV 13, or the highest rating your system and filter slot can accommodate, and says an HVAC technician can help you choose (EPA).

The filter should fit snugly without bending or being crushed. Manufacturers typically recommend replacing filters every 60 to 90 days, sooner if a filter looks heavily soiled (EPA).

Window and ductless units are mainly for temperature control, and EPA says their filters mostly keep the unit itself clean (EPA).

EPA advises avoiding devices that intentionally produce ozone, a lung irritant. It says electrostatic precipitators, ionizers, some UV lights and plasma units can emit ozone, and that no federal agency has approved ozone generators sold as air cleaners for occupied spaces (EPA).

EPA says air cleaners and filters do not address the cause of mold and musty odors. The fix is to remove the moisture source and clean up the mold; a filter may remove some mold particles and sometimes reduce odors (EPA). See hidden mold and controlling moisture.

EPA says several studies with portable HEPA units found small improvements in cardiovascular and respiratory health, and improvements in some allergy or asthma symptoms but not all, and that the changes are typically small and not always noticeable (EPA). Talk with a healthcare professional about symptoms. An air cleaner is not a treatment.

H&H Environmental has operated since 2005 and provides indoor air quality services: testing, sampling, inspection, laboratory analysis, consultation, and air-purification-related services. This guide does not describe what those services involve. Call and tell us what you are concerned about.

On a New York mold project, H&H performs either the mold assessment or the mold remediation — never both on the same project. See mold services.

H&H is based in Saugerties, in Ulster County, and focuses on eight New York counties. Call and tell us where the property is, and we will confirm availability.