Whole-home air purification products connect to your furnace and ductwork, so they treat the air your system moves through the house. The three most common types are media filters, ultraviolet (UV) lights and electronic air cleaners. They work in different ways and remove different things. Before you choose one, it helps to know what each type can and cannot do.
Start with the basics
The EPA lists three ways to improve indoor air, in order of effectiveness: control the source of the pollution, bring in outdoor air through ventilation, and clean the air. The EPA says air cleaning alone is generally not enough. See the EPA page on ozone generators sold as air cleaners.
That means an air cleaner works best alongside basic steps: run bathroom and kitchen exhaust fans, fix moisture problems, avoid smoking indoors and store chemicals outside the living space.
The EPA also notes that a furnace-mounted air cleaner only works while the system fan runs, which is usually less than 25 percent of the time during heating and cooling seasons. Running the fan more often increases how much air passes through the cleaner.
Media filters
A media filter is a deep, pleated filter that sits in a cabinet next to the furnace. It captures particles mechanically as air passes through.
- What it removes: dust, pollen, pet dander, mold spores and fine particles such as smoke, depending on the MERV rating.
- Strengths: no ozone, no electrical parts to maintain, and the greater depth allows higher-MERV media with less airflow restriction than a 1-inch filter. The EPA's guide to air cleaners in the home recommends furnace filters rated at least MERV 13, or as high as your system can accommodate.
- Limits: does not remove gases or odors, and the filter must be replaced on the manufacturer's schedule.
UV lights
UV germicidal lights mount inside the ductwork or near the indoor coil. They are aimed at the damp surfaces where microorganisms grow.
- What they do: according to the EPA's answer on UV lamps and mold, well-designed UV units may destroy biological growth on moist HVAC surfaces such as cooling coils, drain pans and ductwork.
- Limits: the EPA says typical home UV units have limited effectiveness at killing bacteria and molds in the air, because most spores need far more UV exposure than a home unit provides. Dead mold spores can still cause allergic reactions, so UV lights may not reduce allergy or asthma symptoms. UV lights do not capture dust or other particles.
- Ozone note: the EPA warns that UV lamps without adequate coatings may produce ozone.
Electronic air cleaners
An electronic air cleaner, also called an electrostatic precipitator, gives particles an electrical charge and then collects them on oppositely charged plates or media. Ionizers work in a related way, releasing charged ions so particles stick to surfaces.
- What they remove: dust, smoke and other fine particles.
- Limits: collector plates must be cleaned regularly to keep working, and these devices do not remove gases. The EPA notes that ionizers in recent tests removed particles less effectively than high-efficiency filters or electrostatic precipitators.
- Ozone note: the EPA lists air cleaners with electrostatic precipitators and ionizers among devices that may emit ozone.
The EPA's warning about ozone
Some products are sold as air cleaners but are designed to produce ozone on purpose. The EPA's position on these is clear:
- Ozone is a lung irritant. Even relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation, and can worsen asthma.
- No federal agency has approved ozone generators for use in occupied spaces.
- Ozone does little to remove indoor pollutants at levels that meet public health standards, and it does not remove particles such as pollen or dust.
- Terms like "energized oxygen" or "pure air" are misleading. Ozone is not the same as oxygen.
The EPA advises avoiding air cleaners and furnace filters that intentionally produce ozone. If you are considering an electronic air cleaner, ionizer or UV product, check whether it appears on the California Air Resources Board list of certified air cleaning devices. CARB certifies that electronic devices, including in-duct units, meet an ozone emission limit of 0.050 parts per million. CARB notes that its certification covers ozone and electrical safety only, not how well the device cleans the air.
How to choose
- Dust, pollen, dander or smoke: a high-MERV media filter is the most direct, low-maintenance option.
- Mold or film on the indoor coil and drain pan: a UV light aimed at those surfaces may help, in addition to a filter.
- Fine particles with an existing electronic air cleaner: keep the collector cleaned and confirm the model's ozone certification.
- Odors or chemical fumes: address the source and improve ventilation. None of these three options is designed to remove gases.
Before you buy, check your own home: change your current filter, note any musty smells near the furnace, and look for water around the indoor coil drain.
When to call a professional
Call for an evaluation if your system cannot accept a deeper filter, if you see mold or standing water near the furnace or indoor coil, or if you want to add UV or an electronic air cleaner and need help checking ozone certification and fit. A technician can inspect your system, measure airflow and recommend an option that matches your goals. Learn more about whole-home air purification at Krinkie's.
Common questions
Do whole-home air purifiers produce ozone?
Media filters do not. The EPA notes that electrostatic precipitators, ionizers and some uncoated UV lamps may emit ozone, so check whether a model is certified by the California Air Resources Board.
Will a UV light help with allergies?
Probably not by itself. The EPA says typical home UV units have limited effectiveness against airborne mold and bacteria, and dead mold spores can still cause allergic reactions.
Does a whole-home air cleaner remove odors?
Media filters, UV lights and electronic air cleaners are mainly designed for particles or biological growth, not gases. Controlling the source and improving ventilation are the main ways to reduce odors.