There are so many air purifier brands and models, how do you know which one is right for you and your family? Some points that can help you make an informed choice are discussed below: Type Of Filtration, CADR - A Measure Of Efficiency, Room Size, Features, Cost Of Maintenance, and Price.
To make some comparisons quickly, our Air Purifier Comparison Chart can help you compare room size, price, and filters needed for the many brands and models we carry.
Type Of Filtration
According to the EPA, two types of air cleaning devices can remove particles from the air - mechanical air filters and electronic air cleaners.
HEPA filtration is the gold standard in room air purifiers and is considered to be mechanical filtration because a fan is used to pull air through the filters where particles are trapped on the filter material. HEPA stands for high efficiency particulate air and was developed in the 1940's for laboratory use and became available to consumers in the 1950's. To be True HEPA, the filter must capture at least 99.97% of particles as small as .3 micron in size from air that passes through the filter. For perspective, a human hair is about 70 micron in diameter, so you can see that a micron is extremely small. There is a reason the size of the particle captured is down to .3 (3/10) micron in size. Particles smaller than .3 can be easily inhaled and exhaled and particles larger than .9 are usually trapped by the body's defenses, the tiny hairs in the nose called cilia. The particles in between .3 and .9 are the ones that pose a health threat by entering and lodging in the lungs and sinuses and causing irritation. Particles of this size include house dust, dust from fabrics, pollen, dust mite allergen, many bacteria, auto exhaust particles, mold spores, and particles from laser printers and copiers.
Higher Than HEPA Filtration
Although True HEPA filtration is a minimum of 99.97% filtration of particles down to .3 micron in size, there are HEPA room air purifiers that either capture a greater percentage or a smaller size of particles. For example, HEPA+ Air Purifiers capture 99.99% of particles down to .3 micron. IQAir units provide 99.97% efficiency down to .3 micron, but they go an extra step to filter close to 99% of particles as small as .01 micron. Austin Air Purifiers with HEGA filtration also capture 99.97% of particles down to .3 micron and 95% of particles as small as .1 micron.
While electronic filtration is effective at removing small particles, it is not as effective a method as HEPA filtration for larger particles. Some air purifiers such as Blueair (with zero ozone emission) use HEPA filtration in conjunction with electronic air filters that draw air through an ionization section where particles obtain an electrical charge. The charged particles then accumulate on a series of flat plates called a collector that is oppositely charged. Electronic filtration can produce ozone, so look for the amount emitted. The Food and Drug Administration sets the safe limit at no more than .05 ppm for indoor medical devices.
Gas & Fume Filtration
If you are sensitive to odors and fumes, consider a HEPA air purifier with special filters for the absorption of gases and fumes. All true HEPA air cleaners have a pre-filter that fits over or around the HEPA filter. The pre-filter usually serves two purposes. It captures the bigger particles that would clog the HEPA filter so the life of the HEPA filter is extended, and the pre-filter is generally infused with carbon that absorbs odors. However, if you are especially sensitive to odors or chemical fumes or if there is some strong, irritating odor in your environment, you may need the extra power of a VOC (volatile organic compound) filter. VOC filters contain large amounts of odor filtering substances such as carbon or zeolite and have a much larger capacity for odor absorption than a carbon pre-filter. Many air cleaners either come with this filter or have the option of adding one.
Filters To Avoid
There are air filters to avoid that just don't do the job or that can actually be dangerous. Beware of filters that are called HEPA Type or HEPA Style - they do not meet the specifications of a True HEPA Filter. Machines called ozone generators should also be avoided. According to the EPA, they do not effectively remove particles from the air at safe ozone levels for a small space.
CADR - A Measure of Efficiency
CADR, clean air delivery rate, is a method to compare the efficiency of air purifiers. Not all manufacturers submit their air purifiers for testing, and this does not mean the units are not effective. For units that supply CADR, this rating is a tool for you, the buyer, to use to compare air purifier efficiency. Filtration is tested for pollen, dust, and smoke which are the most common pollutants that affect indoor air quality. On the air purifier's box, there is a chart (see below) giving this information. An independent organization, the Association of Home Appliance Manufacturers (AHAM), performs the testing to make sure it is fair and accurate. The Environmental Protection Agency (EPA) uses the same testing method in its Air Cleaner Energy Star Program. By giving measures of three types of particulates, CADR enables you to choose an effective machine to meet your needs. For example, if you are highly allergic to pollen, you want to pick a machine with a high rating for pollen.
Room size determines how effective the air cleaner can be in the room in which it is placed. Check for room dimensions or square footage when you select a model. It is okay if the air cleaner cleans a larger space than your room. As a matter of fact, that is good; the air would be going through the air purifier more times per hour and getting cleaner. If you are not sure what size you need, measure your room and multiply the length times the width for square footage. If the air cleaner gives room size, multiply the length and width and compare to your room's square footage. Room sizes given are for standard 8-foot ceilings. HEPA air purifiers are designed to work in one room. One unit will not be able to clean the air in a whole house. Running the air purifier 24/7 in the bedroom will provide the cleanest possible air for you to breathe all night. You can move an air purifier from room to room during the day to be where you are, but this is not the most effective use of an air purifier.
HEPA air purifiers come with a wide range of features. Some are beneficial for specific needs and others are a matter of personal preference. Here are some features to consider as you make your air purifier choice:
That sounds like a lot to think about, but start by picking the features that are important to you. If any are must-haves, you can eliminate air purifiers that don't have that feature. Then see which brands have what you really want. Once you decide on a brand, choosing the model is mainly based on the size of your room.
- If you plan to move the unit from room to room or for ease of moving when cleaning, handles and casters are helpful.
- If you are chemically sensitive, you may prefer a unit with a steel cabinet and baked on finish that does not off-gas and a unit with a special filter for gases or the option to add that type of filter.
- For people with extreme allergies, an extra level of filtration could make a difference so a unit with better than 99.97% down to .3 micron would be a good choice.
- The dimensions of the unit could matter if the room where it would be placed is small or the air purifier needs to fit in a small space.
- When the clean air is exhausted from the top of the air purifier, you can place it against a wall. Some units exhaust air from all sides and must be placed at least a few inches from walls or furniture. This could also make a difference in a small space.
- For convenience, you may want a unit with a remote control, filter change indicator lights, and easy-to-reach filters to make changing them easier.
- All HEPA air cleaners are going to make some noise because they work by having a fan draw air through the filters. If you are sensitive to noise, the decibel level of the unit may be important to you.
Cost of Maintenance
The main cost of maintenance of HEPA air purifiers is replacement filters. Replacing filters as directed by the manufacturer is key to optimum performance by any HEPA air purifier. See how often filters should be replaced and the cost of the filters. Looking at the cost per year is a good way to compare the cost of replacement filters. Some brands are designed to need new pre-filters every three months and new HEPA filters every year. Others have filter packs that last up to 5 years. Keep in mind that the estimated life of a filter is under normal use which would be 24/7 operation in a typical home. If you have an unusual circumstance such as construction in your home or neighborhood or more than one or two pets, filters may need to be changed more often. When filters are not replaced regularly some filtration ability is lost and the motor of the unit could be damaged.
When you have narrowed down the size of air cleaner you need and the features you need and want, then you can compare prices. All HEPA air purifiers perform the same function - removal of 99.97% of particles down to .3 micron. The price you pay is dependent on the size of your room, additional filtration you may want or need, and the features that are important to you.
The filtration of allergens and other particles from your home's air can make a big difference to your family's health, especially for allergy and asthma sufferers. Hopefully, the information above will make it easier for you to choose the right air purifier for you.
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