Air Purifier Buying Guide
April 21, 2020, by Lisa Powers
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There are hundreds of portable indoor air purifiers on the market. Finding the best one for your needs can be a daunting task. Most air purifiers, particularly inexpensive models, only filter particulate matter but do nothing to remove gases, VOCs and odor. If your goal is to remove as many of the most harmful contaminants as possible from your indoor air you need to look for air purifiers that remove both particulate and gaseous matter.
5 Things to Consider When Buying an Air Purifier
Type of Filtration
Most filters are designed to remove either particles or gases. A unit that does both will have two or more types of filters. For example, a unit with only HEPA filtration will do nothing to eliminate gaseous pollutants.
HEPA
HEPA stands for high-efficiency particulate air. True HEPA filters are manufactured and certified to a standard in which 99.97% of all particles that have a size greater than or equal to 0.3 microns are captured. But not all HEPA filters perform equally. Some air purifiers with True HEPA filters can have different levels of efficiency and performance. Keep reading to learn why efficiency is an important criteria when choosing an air purifier.
Sorbent Media
Sorbent media filters use material with very high surface area to capture gaseous pollutants.
Activated Carbon
This is the most common type of sorbent filter used in air purifiers. Carbon can be very efficient at capturing gaseous pollutants but it does not destroy them. According to the EPA, filters must be properly maintained to prevent the carbon from becoming saturated. Once saturated, captured gases can break through and re-release into the air. Carbon is typically not as effective at removing low-weight aldehydes such as formaldehyde.
Some filters use chemisorption to stabilize gases and to help to target a variety of chemicals activated carbon cannot effectively remove. Chemisorption occurs when a gas reacts with an agent that is impregnated into the sorbent media.
Earth Minerals
This is a proprietary type of sorbent media that is used in EnviroKlenz purifiers. It is comprised of zinc oxide, magnesium oxide, and titanium dioxide. The earth minerals adsorb, neutralize and breakdown the chemical compounds into basic, non-toxic elements. This media also uses chemisorption to stabilize chemical compounds.
UVGI
Ultraviolet Germicidal Irradiation uses UV lamps to kill or deactivate captured microorganisms such as bacteria, mold spores, and viruses.
PCO and PECO
Photocatalytic Oxidation (PCO) uses UV light and a filter coated with titanium oxide to convert harmful pollutants into harmless water and carbon dioxide. PCO can be effective at transforming many pollutants but may produce chemical by-products, such as formaldehyde, and some may produce ozone.
PECO, photo electrochemical oxidation, is the proprietary technology used by Molekule. PECO was developed based on similar principles as PCO, photocatalytic oxidation, but it uses a different type of UV light to begin the chemical reaction that breaks down the pollutants and claims to not produce ozone or chemical by-products.
Ozone Generators
Ozone generators produce ozone which react with chemical and biologic pollutants and break them down or destroy them. Ozone is a lung irritant and its production can produce harmful by-products. No federal agency has approved ozone generators for use in occupied spaces.
2. How Well Does it Remove Particulate Matter?
There are 3 factors that will help you compare different air purifiers ability to remove particulate pollution; efficiency, air delivery rate, and room size coverage.
Efficiency
This is the percentage of a concentration of particulate pollutants that are removed when they move through the unit. For example, HEPA filters must have an efficiency of 99.97% for particles 0.3 microns and larger. Some manufactures will give a total efficiency percentage as well as percentages for different sized particles. This is helpful because not all models are as good at removing smaller particles.
Particulate matter can be categorized based on its size.
Course particles (2.5 to 10 microns) include pollen and mold spores.
Fine particles, (0.1 microns to 2.5 microns) include household dust, bacteria, pet dander, and virus.
Ultra-fine (<0.1 microns) include some wildfire smoke, tobacco smoke, soot, and some virus.
If you are concerned about removing a particular contaminant, look for the efficiency for that size. Make sure the unit removes a high percentage of pollutants in that size range.
Clean Air Delivery Rate (CADR)
This measure tells you the volume of air that can be filtered by an air purifier in one minute. The higher the CADR, which is expressed in cubic feet per minute (cfm), the more air can be processed in a room in a given timeframe and the larger the room it can clean. The CADR is based on running the unit at the highest fan speed. Generally speaking, a delivery rate of 250 cfm is considered very good.
While CADR is one metric to look at, it has limitations. It is only a measure of particulate pollution and tells you nothing about a unit’s ability to remove chemical VOCs, gases or odors. Additionally, it favors units that perform well very quickly but doesn’t evaluate performance over a longer period of time.
Room Size
Most manufacturers provide an estimate of how large a room the unit can clean. These calculations are usually based on a room with an 8ft. ceiling. If you have a higher ceiling, the coverage will be less than stated. You may need multiple units if your room is larger the recommended room size.
3. How Well Does it Remove Gases?
There is no standard for comparing how well air purifiers remove gases. If comparing air purifiers brands or models that each use activated carbon, the ones with more carbon weight will generally be more effective. Those that also use chemisorption will be more effective at destroying formaldehyde and other VOCs. For brands and models that use other technology, you will need to reply on third-party testing to assess their performance.
4. Test Results and Reviews
When reading testing results on manufacturers websites make sure the data is independent third-party tested with specific information on who conducted the testing and under what parameters. The greater the transparency around the testing, typically, the greater confidence you can have in the results. Consumer reviews can also be helpful but be aware that most of the reviews that compare different air purifiers evaluate larger particle removal and not removal of fine particles or gases. Make sure you understand what is being evaluated.
There is currently very limited independent research available and more is needed to compare air purifiers that claim to remove chemicals and gases.
5. Price
Models that I am recommending here range in price from $699 to $1299. Most units that removes gases as well as particles are more expensive because they use multiple filter technologies.
Recommended Air Purifiers
Most air purifiers are designed to remove particulates and do nothing to remove gases. But gases such as formaldehyde from building products and carbon monoxide from cooking combustion can be among the most dangerous pollutants in your indoor air. For this reason, my air purifier ratings are based on a product’s ability to remove both particles and gases. If you are only interested in removing particles, skip the rating report card and read the reviews I’ve written for each product. You can compare the efficiency and air delivery to find a product that is right for you. Also, if your primary interest is removing large molecule allergens like pollen there are many lower-cost options not covered here.
These ratings are based a product’s ability to remove both particulates and gases. Some that are not rated as well may very good at removing one or the other but not both.
Best Air Purifiers
IQAir GC MultiGas
Technology: True HEPA filter
Activated Carbon (12lbs.)
Chemisorption
Room Size: Maximum 1240 sq. ft.
Efficiency: ≥ 99% for particles ≥ 0.3 microns
≥ 95% at ≥ 0.003 microns
Air Delivery: 780 cfm
Price: $1299
Filter Replacement Cost: Prefilter ($78) every year, Gas cartridges ($295) every 2.5 years, Post-filter sleeves ($95) every 2.5 years
Testing and Reviews:
IQAir does not provide testing data on their website but the testing on the EnviroKlenz website shows that this is extremely effective at removing formaldehyde. The Allergy Buyers Club rates it as the category winner for VOC and chemical removal because it is able to deliver excellent fine and ultra-fine particle removal as well as address specific chemicals and gases.
Bottom Line:
This is a top-of-the-line unit that does an excellent job of removing particles, even the most concerning fine and ultra-fine particles, as well as a range of chemicals, gases and odor.
Airpura V600
Technology: HEPA Filter
Enhanced Activated Carbon (18lbs.)
Room Size: Maximum 2000 sq. ft.
Efficiency: 99.97% for particles ≥ 0.3 microns
Upgrade to SuperHEPA: 99.99% for particles ≥0.3 microns
Upgrade to ULPA: 99.99% for particles ≥0.1 microns
Air Delivery: 560 cfm
Price: $799.98
Filter Replacement Cost: Pre-filter ($39.98) every year, Carbon filter ($279.98) every 2 years, TrueHEPA ($179.98) every 3-5 years.
Testing and Reviews:
Airpura does provide third-party testing that shows performance against virus, bacteria and mold. Additionally, they provide testing that confirms the very strong performance of their HEPA filters. While they reference removal rates for gases based on a third- party test done by a distributer, they do not provide details of testing conditions so it is difficult to assess those removal rates.
Bottom Line:
This unit is very good choice for removing both particles and gases. The standard HEPA filter will remove coarse particles but upgraded filters are available to remove fine particles as well. It is not designed to remove ultra-fine particles such as wildfire smoke. With 18 pounds of carbon it should do a very good job of removing gases. This model does not include a chemisorbent media so it may not be as effective at removing low- weight gases such as formaldehyde.
Better Air Purifiers
IQAir HealthPro Plus
Technology: True HEPA filter
Activated Carbon (5lbs.)
Chemisorption
Room Size: Maximum 1125 sq. ft.
Efficiency: ≥ 99.97% for particles ≥ 0.3 microns
≥ 99.5% at ≥ 0.003 microns
Air Delivery: 780 cfm
Price: $899
Filter Replacement Cost: Prefilter ($69) every 1.5 years, V5-Cell filter ($99) every 2 years, HyperHEPA filter ($199) every 4 years
Testing and Reviews:
Allergy Buyers Club rates this as the category winner for HEPA air purifiers.
Bottom Line:
Compared to the IQAir GC MultiGas, this model is even more efficient at fine and ultra-fine particle removal but not as powerful against chemicals, gases and odor. If you are concerned about smoke, virus or other ultra-fine particles, this might be the model for you.
Austin Air Healthmate Plus
Technology: True HEPA filter
Activated Carbon (15lbs.)
Chemisorption
Room size: Maximum 1500 sq. ft.
Efficiency: 99.97% for particles ≥0.3 microns
95% for particles ≥0.1 microns
Air Delivery: 400 cfm
Price: $715
Filter Replacement Cost: Replacement Filter ($360) every 5 years.
Testing and Reviews:
Austin Air purifiers are sold on many sites and have positive consumer reviews. There is a lack of independent testing showing how it compares to the other recommended units but based on its technology and efficiency at removing particles, it is a solid choice.
Bottom Line:
This is a simple but well-made unit by a company that has been around for a long time and stands behind their products.
EnviroKlenz Mobile Air System
Technology: True HEPA filter
Earth Minerals material
UVGI (for UV Model)
Room Size: Maximum 1000 sq. ft.
Efficiency: 99.99% for particles >0.3 microns
Air Delivery: 250 cfm
Price: $699 without UV, $799 with UV.
Filter Replacement Cost: Earth mineral filter ($99) every 6 months, HEPA filter ($150) every 2 to 3 years.
Testing and Reviews:
EnviroKlenz provides extensive laboratory testing results on their website that compares their product with IQAir, BlueAir and Molekule. The testing shows the unit to be very effective at removing a range of VOCs. Additionally, they submitted a unit for review to Vacuum Wars, an independent review and comparison channel on YouTube. It is not a laboratory, but it does conduct an unbiased chamber test.
Bottom Line:
EnviroKlenz is a powerful unit that effectively cleans both particulate and gaseous pollutants. It is a simple, no frill model made with a powder coated metal housing. Some readers on this site have reported quality control and customer service concerns though the EnviroKlenz website shows very positive reviews. The UV model provides extra protection against virus, mold and bacteria.
Use with Caution (these may do a good job of removing either particulate matter or gases but not both)
Air Doctor
Technology: HEPA Filter
Activated Charcoal (2.2lbs.)
Chemisorbent media (impregnated with potassium permanganate)
Room Size: Maximum 2400 sq. ft.
Efficiency: 99.9% for particles ≥0.3 microns
99.95% for particles ≥0.003 microns
Air Delivery: 326 cfm
Price: $629 plus shipping, promoted price can be as low at $329
Filter Replacement Cost: UltraHEPA filter ($59.95 plus shipping) every year, Gas filter ($59.95 plus shipping) every 6 months.
Testing and Reviews:
Independent third-party testing confirms air delivery rates. There is no testing for performance against gases, chemicals and odor.
Bottom Line:
There is very little activated carbon in this unit. This unit does deliver very good particle removal including ultra-fine particles. If particle pollution is your primary concern this may be a good choice. If you are looking to also remove gases, chemicals and odors there are better options available.
Airpura C600DLX
Technology: HEPA Barrier (not true HEPA)
Activated Carbon (26lbs.)
Chemisorbent Media (proprietary blend including potassium permanganate)
Room Size: Maximum 2000 sq. ft.
Efficiency: 95% for particles ≥1.0 microns
Air Delivery: 560 cfm
Price: $899.98
Filter Replacement Cost: Pre-filter ($39.98) every year, Carbon filter ($349.98) every 2 years, HEPA filter ($99.98) every 3-5 years.
Testing and Reviews:
Airpura does provide third-party testing that shows performance against virus, bacteria and mold. While they reference removal rates for gases based on a third-party test done by a distributer, they do not provide details of testing conditions so it is difficult to assess those removal rates.
Bottom Line:
This model is designed for chemical, gas and odor removal. The tradeoff is that is does not do much to remove fine or ultra-fine particles. Based on the very large amount carbon combined with chemisorbent media it should be very effective at removing gases. If gases are your primary concern this is a good choice.
There are several Airpura models that address specific issues like mold and virus, formaldehyde, etc. If there is something specific you need to address you might want to look into those choices.
Avoid (not likely to perform as well as other rated purifiers for either particulate matter or gases)
Aireox 45D
Technology: Activated Carbon (4lbs.)
Chemisorbent Media (impregnated with potassium permanganate)
Room Size: Not Available
Efficiency: 99.26% for particles ≥ 0.3 microns
Air Delivery: 125 cfm
Price: $359.95 plus shipping
Filter Replacement Cost: Carbon filter ($94.95) every year.
Testing and Reviews:
There is no third-party testing published for this unit.
Bottom Line:
This unit is designed for chemically sensitive people and does not use any adhesives which could cause odor. It is primary designed to removes gases, chemicals and odor but with just 4 pounds of carbon it is not nearly as powerful as some other brands. It has relatively low air delivery and does not have a HEPA filter so it is not likely to be effective at removing ultra-fine particles.
Why I Haven’t Rated Molekule (updated October, 2020)
I own a Molekule and purchased it when it first came out because of the extensive third-party testing they provide on their website. The data shows compelling performance against VOCS, mold, bacteria, and virus, and provides evidence that no ozone or by-products are emitted. Experts have verified these results.
Consumers love the product. Repeat purchases are 200% which means people who own a unit are happy enough to go back and buy additional units.
Most reviews that have rated Molekule poorly only test for a short period of time and Molekule’s testing shows strong results over longer periods.
So, why don’t I rate it?
Molekule’s technology is unique and is difficult to compare using metrics like CADR and the weight of sorbent media. The best way to compare it to other brands is by independent third-party testing.
While Molekule’s provides extensive and compelling testing on their website, the claim that the testing is “independent” was challenged by Dyson, a competitor. A report by Wirecutter revealed that the makers of Molekule were advised by the NAD, an investigative division of the Better Business Bureau, to remove claims of “independent” testing from their marketing because much of the testing was done at labs which had received sponsorship from the company or where the founder was a director. Molekule challenged the Wirecutter report in detail and asserts that the founder had a relationship with just one testing facility. They have tested with three other independent and well-known laboratories and produced results that support their claims.
I have been in contact with Molekule and they have been transparent and forthcoming with information. I believe it’s likely this new technology performs as well as the manufacturer claims and as the test results show. If you are interested in this brand I recommend reading both the Wirecutter article and Molekule response to form your own opinion.
For chemically sensitive individuals, you may want to also look at mychemicalfreehouse.net which has a good overview of different media and purifier components that may cause a reaction. Additionally, make sure you understand the return policy for the unit you plan to purchase so if you are not able to tolerate it you have the option of sending it back.
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