Learn More About Air Cleaners
Here is what you get exclusively from
- Types of air cleaners
- Can air cleaners handle odors?
- How to choose an air cleaner?
- How to improve an air cleaner's performance?
- Where to find more information?
- Air Cleaners
- Clean Air Information Page
- Asthma and Allergy Avoidance Information
- Portable Air Conditioners Information Page
- Air Humidifiers Information Page
- Dehumidifiers Information Page
- Car Cabin Air Filters Information Page
If you have a question about air cleaners that is not covered here, please e-mail us at firstname.lastname@example.org, and we will do our best to answer it.
Breathing clean air is very important for your health. Polutant-free air can reduce asthma and allergy symptoms, plus the need for medication. Using an air cleaner offers real relief by removing pollen, pet dander, smoke, mold spores and household dust from the air. It is important to choose the right air cleaner that best suits your needs.
Types of air cleanersThe three major types of air cleaners include:
- HEPA Air Cleaners: HEPA stands for "High Efficiency Particle Arrestor", a filter standard that can capture 99.97% of particles as small as 0.3 microns. It also captures particles below 0.3 microns and can be 95-99% effective at doing so. Such filtration is adequate for capturing most common household allergens, like dust, mold spores, pet dander and tobacco smoke particles.
HEPA filters were originally designed to trap microscopic particles such as radioactive dust in nuclear plants and are commonly used for critical environments like hospitals, clean rooms and lead abatement projects.
Some HEPA air cleaners are advertised as having "permanent" filters. While the filters on certain models may indeed need no replacement, most of the time this means that the HEPA filter can be vacuumed, thus increasing its effective life up to five years or more. "Permanent" filters are usually more expensive than standard HEPA filters, but, keeping in mind a standard HEPA filter's lifespan of about a year, "permanent" ones are more cost-effective in the longer run.
Brands that offer HEPA filtration include: Honeywell, Austin Air, Blueair, Bionaire, and Hunter HepaTech.
- Electrostatic/Ionic Air Cleaners: As the particles pass into the air cleaner an electric charge is given to them. The charged particles are then attracted to walls, floors, draperies, etc., or to a series of flat plates with an opposite electrical charge. They effectively remove particulate from the air, such as allergens (including mold and dust mites), fine dust particles, bacteria, viruses, chemical fumes and other ultra-fine particles.
Brands that employ this feature include: Sharper Image Ionic Breeze, Hoover, Slant/Fin, and some of the Hunter HepaTechs.
- Electronic Air Cleaners: Somewhat similar to electrostatic air cleaners, these use an electric field to trap the particles without releasing them outside, where they may soil walls and other surfaces.
Brands that employ this feature include: Friedrich.
Other types of air cleaners include:
- Air Washers: By drawing the air through water, an air washer naturally cleanses the air of smallest air borne particles, just like outside air is washed by rain. It also serves as a humidifier.
Brands that employ this feature include: Air-O-Swiss.
- Air Sterilizers: The air passes through a heating chamber, which destroys airborne organic allergens, molds, viruses and other microorganisms. Although air sterilizers may be less effective against non-organic pollutants like dust and tobacco smoke, they are highly recommended when dealing with mold infestations.
Brands that employ this feature include: Airfree.
- Ultraviolet Light: Usually used as a secondary air cleaning device in an air cleaner of one of the major types. Ultraviolet light is very effective at destroying microorganisms such as bacteria, mold and viruses.
Brands that employ this feature include: Sharper Image Ionic Breeze.
Can air cleaners handle odors?Most odors in the air are produced by gases, and not every air cleaner is designed to handle them. That is why you may smell a tobacco odor, for example, even when tobacco smoke particles have been removed.
Some ways in which air cleaners combat odors are:
- Activated Carbon Pre-filters: Usually placed before a HEPA filter, these serve two purposes. The activated carbon in a pre-filter absorbs odors, and also traps larger particles that may damage the HEPA filter - thus increasing its lifetime.
Most HEPA air cleaners have this feature.
- Carbon / Zeolite: Filters inside the Austin Air HEPA Air Cleaners have a layer of this material, which acts like a sponge for gases and odors. It offers even better odor protection than just plain activated carbon.
How to choose an air cleaner?What to consider:
- Pollutant type. Different air cleaners work best against different kinds of pollutants.
- Room size. Most air cleaners have a room size rating in their description. If an air cleaner is used in a room which exceeds its rating, it will not work adequately. Air cleaners with higher ratings than is needed usually consume more power than necessary - although, if you cannot find an air cleaner that exactly matches your room size, it is better to have one with a higher rating.
- The amount of air handled by the device. For example, an air cleaner may have a high efficiency filter, but it may process only 10 cubic feet of air each minute. Suppose that the air cleaner is put in a room of typical size, containing 1000 cubic feet of air. In this room, it will take a long time for all the air to be processed. In some cases, pollutants may be generated more quickly than they are removed. This can be represented by one or both of the following values:
- CFM: This stands for "cubic feet per minute", the total amount of air that flows through an air cleaner per minute. 1 CFM equals approximately 2 liters per second (l/s). You'll get best results with an air purifier capable of cycling the air in your room at least six times an hour.
- CADR: Or, the "Clean Air Delivery Rate", which measures the amount of clean air delivered by the unit. It is usually shown in values for tobacco smoke, pollen and dust - the higher the numbers, the faster the unit filters the air of these pollutants. Among these, the number for tobacco smoke is the most important, since tobacco smoke particles are harder to remove from the air. AHAM recommends choosing an air purifier with the tobacco smoke CADR of at least 2/3 of your room's area (higher if you have high ceilings).
- Air flow and ventilation. A single portable unit used in a room within a large building in which the air flows between several apartments or offices would be of little or no value.
Each type of air cleaners has its own quirks which should be considered when buying one.
- HEPA Air Cleaners tend to be noisy, even at a low speed setting (Honeywell QuietCare units have the lowest noise level among the air cleaners of that type). They may also have a high maintenance cost, since replacement HEPA filters can be quite expensive.
- Electrostatic and Electronic Air Cleaners may produce ozone, particularly if they are not properly installed and maintained. Ozone is a lung irritant and can be dangerous to your health when its concentration is high. Electrostatic air cleaners, especially those that do not contain a collector, may cause soiling of walls and other surfaces.
How to improve an air cleaner's performance?
- Proper installation, use and care. Follow the manufacturer's directions to assure that the air cleaner works properly.
- Proper placement. Place portable air cleaners so:
- They are near a specific pollutant source, if one exists.
- They force the cleaned air into occupied areas.
- The inlet and outlet are not blocked by walls, furniture, or other obstructions.
- Proper maintenance. With time, the performance of an air cleaner may decrease as the pollutants collect on the filtering media. Make sure to regularly replace the filters, pre-filters and collection sheets of your air cleaner. As a rule of a thumb, a HEPA filter needs to be replaced once a year, and a pre-filter every six months. If you have a permanent filter, it needs to be vacuumed approximately every other month (don't try to vacuum standard HEPA filters, since this may damage the delicate filter material).
We suggest using only HEPA vacuum cleaners to clean permanent filters, since otherwise the fine dust that had accumulated in the filter will get back into the air with the vacuum's exhaust. It's a good idea to wear a dust-proof face mask while changing the filter, to keep yourself from inhaling dust.
- Additional measures. Air cleaners cannot pick up particles that are not suspended in the air. You will have to deal with pollutants settled down on floors, walls and furniture manually. A good vacuum cleaner and appropriate cleaning supplies are essential in that.
Where to find more information?
- US Environmental Protection Agency:
- CADR.org - this site by the Association of Home Appliance Manufacturers (AHAM) has some helpful information about selecting an air purifier, and what do the CADR numbers mean.
- Portable Air Purifiers for Airborne Infection Control - an article by Dr. Roy M. Speiser