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How to find the best air purifier

Article at a Glance
  • Many people may think they need an air purifier because they have allergies or asthma. But not all air purifiers are created equal. What you buy — and buying it for the right reasons — matters.
  • When used in a room where we spend most of our time (like our bedrooms, when we sleep), air purifiers can improve indoor air quality (IAQ) by trapping particles in HEPA and/or activated carbon filters. You’ll want to beware any products that use ozone generators, UV lights, or ionizers, as all of these may emit some level of ozone, which is bad for us.
  • The best air purifiers to buy depend on what you’re looking to accomplish, though Consumer Reports and air-purification experts tend to lean toward HEPA filters for their safety (they generally do not emit ozone) and overall effectiveness.
  • Knowing the Clean Air Delivery Rate (CADR) rating for dust, pollen, and smoke, and knowing if your air purifier emits ozone or not is crucially important. Some air purifiers also will clean larger areas faster, and trap smaller particles than their competitors.
  • Setting up your air purifier in the correct place — and preparing your home before even purchasing a purifier — matters. There are several steps you can (and should) take to improve your IAQ, such as frequent vacuuming with a quality vacuum and changing HVAC filters regularly and ensuring proper maintenance.
  • We recommend air purifiers that offer a high CADR with zero ozone, including IQAir HealthPro Plus and Blueair Classic 605.
Genes Mentioned
ozone free air purifiers

John has written a lot on this blog about histamine genes like AOC1 and his strategies for beating histamine intolerance, so the topic of air purifiers seemed like a natural fit. We know that air purifiers can do some good, but how do you go about choosing one?

We set out to answer the hard questions.

Do air purifiers work — and if so, how do they work? How do I find the best air purifier? Do some air purifiers emit ozone and therefore do more harm than good?

We spoke with an air-purification industry expert at Long’s Vacuum & Appliance, which has been in business for over 60 years in Austin, to find out. Weldon Long is a second-generation owner of the shop. The Longs’ primary business was vacuums, but they expanded to include air purifiers about 15 years ago — back when it was the “wild, wild west.”

“It was nothing more than ozone generators then,” Long says.

Do air purifiers really work?

Science Score:  

We can start here, because if air purifiers don’t work, who needs one?

Yes, air purifiers work. They remove particles, such as allergens, from the air, but some air purifiers definitely work better than others. The U.S. Environmental Protection Agency (EPA) doesn’t endorse any claims from air-purifier manufacturers that their product actually makes the air around us healthier, but they definitely warn against the dangers of ozone generating air purifiers. In fact, the EPA has a whole section on their website warning against using the danger of using the wrong air purifier.

However, when you remove ozone from the equation, and it comes down to the efficacy of an air purifier, the major factors are:

  1. purifier efficiency
  2. airflow rate and;
  3. particulate matter load.

Per the EPA:

“For example, a filter may remove 99 percent of the particles from the air that passes through it (i.e., have 99 percent efficiency). However, if the airflow rate through the filter is only 10 cubic feet per minute (cfm) in a typical room of approximately 1,000 cubic feet (e.g., 10’ x 12’ x 8’), the filter will be relatively ineffective at removing particles from the air (i.e., 10 times less effective than if the airflow rate were 100 cfm).”

So, bottom line, you want to buy an air purifier that not only removes the bad stuff from the air, but one that cycles through enough air to clean the air in the room you’re living in.

HVAC filters are not effective air purifiers

A quick note about HVAC systems. You may be thinking, my HVAC cycles through all the air in my house and it has a filter, that is probably good enough, right? Wrong.

Think again. In a review of studies addressing the effectiveness of air filters and cleaners at alleviating allergy symptoms, “inexpensive, low-efficiency HVAC filters offer no better particle removal than no filter.” (R)

This is why an air purifier properly placed in the right sized room can be effective: it has a chance to cycle through much of the air in the room and remove the bad stuff the HVAC system isn’t equipped to get.

What is the difference between air purifier types?

There are two types of air cleaning devices: those that “remove” particles or pollutants, and those that “destroy” particles.

The removers: Mechanical air filters like HEPA filters remove particles by capturing them, while electronic air cleaners use electrostatic precipitators to trap charged particles on a series of plates that are oppositely charged. Finally, gas-phase air filters use activated carbon or another sorbent to remove one or more gaseous pollutants from the air. You may see air filters in stores or online using more than one removing technology, such as a HEPA filter with activated carbon.

The destroyers: Ultraviolet radiation cleaners and ozone generators are intended to destroy pollutants, but they’re also dangerous. According to the EPA: “Ozone generators that are sold as air cleaners intentionally produce ozone gas, a lung irritant, to destroy pollutants. … At concentrations that do not exceed public health standards, ozone has little effect in removing most indoor air contaminants.”

So, a few air purifiers you definitely want to stay away from, while some are more effective in getting rid of the gunk in our air. There are of course some myths surrounding air purifiers. Air purifiers don’t really “kill” any of the bad guys – germs, even — they just trap them until their filter is changed. That’s where any brands with washable filters get tricky, too.

“We want to trap as much air as we can trap, and then throw it away,” Long says.

Air purifiers and pollutants

Air cleaning technologiesPollutants removedLimitationsFound on Amazon
Air filters (HEPA)ParticlesIneffective in removing larger particles because they typically never reach air filters and instead settle in the airGermGuardian AC4825 3-in-1 Air Purifier
Gas-phase filters (including activated carbon)GasesShorter lifetime and not as effective in removing some gases, like carbon monoxideSun-Pure SP-20C Portable Catalytic Air Purifier
UVGI (ultraviolet germicidal radiation)BiologicalsBacteria and mold are resistant to UV; should be applied with filtration systems and not as a replacement for filtrationSilverOnyx 4 in 1 Air Purifier
PCO (photocatalytic oxidation, type of UV)GasesNot as effective, and do not remove particulatesG2000 Air Purifier Whole House TIO2 PCO Photocatalytic Filter
Ozone generatorsParticles, gases, biologicalsNot safe or effectiveIvation 5-in-1 HEPA Air Purifier & Ozone Generator, Ionizer & Deodorizer

Source: Environmental Protection Agency Guide to Air Cleaners

HEPA (ozone free air purifiers)

HEPA, or high-efficiency particulate air, is a type of extended surface filter. (R) HEPA filters trap dust, pollen, and smoke without emitting ozone. In one Finnish study, when HEPA filters were installed in occupational buildings, they reduced workers’ exposure to particulate matter associated with high mortality by 27%. (R)

Activated carbon technology (no ozone)

Activated carbon removes impurities in the air through chemical absorption. You’ll probably notice this type used in water filters, but it’s also in some air purification systems.

Ozone air purifiers

The purpose of an air purifier is to get rid of irritants in the air, right? Well, ozone purifiers actually can cause our lungs to breathe in more irritants. That’s what ozone is — a lung irritant. Ozone generators are banned from sale in California. Some types of ozone purifiers have been shown to emit 20 times the voluntary ozone standard set by the U.S. Food and Drug Administration. (R) The California Air Resources Board (CARB) has a full list on potentially hazardous ozone-producing air purifier models that is worth taking a look at if you’re running an older model in your home.

UV technology (ozone possible)

UV air purifiers use a HEPA filter first, and then the air enters another chamber to be exposed to UV-C light, which does not release into the room. The UV light in these air purifiers claims to kill particles and germs, but they’re not always safe or effective. Part of the technology of ozone generators is to use UV light or an electrical discharge to intentionally produce ozone, so while not marketed as ozone-producing air purifiers, UV air filters also release ozone. (R)

Negative ion (ozone possible)

These types of electrostatic precipitators have been popular with consumers in recent years. Negative air ions attract dust and allergens, with one study finding that breathing in air cleaned by this type of filter could reduce symptoms of depression. (R) However, if an air purifier has an ionizer, it can produce ozone, which has negative effects on asthma and other lung issues. Ionizers also only remove particles from the air — they do not remove gases or odors.

Ranking the best ozone free air purifiers

While Consumer Reports (CR) has published buyers’ guides for air purifiers for years, Long doesn’t necessarily recommend following their advice. He contends that IQAir is the best air purifier on the market, hands down, while Consumer Reports doesn’t even rank IQAir in its latest guide (it was ranked 20 in 2007).

Long says most brands on CR you can buy at a big-box store, like Sears, Target, or Walmart, and therefore the focus may be on what’s most budget-friendly for consumers rather than longevity of the product. He says he sees it with vacuum rankings, as well.

Still, it helps to know a little about the process and do some research yourself. CR tests for how well air purifiers remove dust and smoke from an enclosed space, their performance at high and low speeds, and how quiet they are. According to CR, “air purifiers that draw air through fabric filters are among those that do the best job of removing dust and smoke from the air without producing any ozone.” (R) HEPA filters fall under this category.

Air purifier CADR above 350

Additionally, CR suggests looking for portable air purifiers with a CADR (Clean Air Delivery Rate) above 350, which is considered excellent, and to look for that rating with an Association of Home Appliance Manufacturers (AHAM) logo. Prices for what CR considers good air purifiers range from $250 to over $1,000; the IQAir costs about $900.

Note that while you’ll pay for the cost of the air purifier up front, there are other costs such as replacing filters and energy costs to take into consideration — typically about $175 to $200 per year. A standard air purifier operating continuously may use more energy per year than your refrigerator, for instance.

Here are a few of the top-rated air purifiers for large rooms, 350-650 square feet, according to Consumer Reports.

Air purifier brand comparison

Air purifier brandType of technologyAHAM effectiveness ratingOzone safety
Blueair Blue Pure 211Activated carbon filterNot rated, but claims to cover 540 square feetNo ozone
Blueair Classic 605HEPA filter (activated carbon filter option sold separately)Per 698 square feet: dust CADR > 400, pollen and tobacco smoke CADRs > 450No ozone
Honeywell HPA300Activated carbon and HEPA filtersPer 465 square feet: dust CADR > 320, pollen and tobacco smoke CADR > 300No ozone
Alen BreatheSmartFour HEPA filter optionsNot rated, but claims to cover 1,100 square feetNo ozone
IQAir HealthPro PlusHyperHEPA filterNot rated, but IQAir is tested and certified to filter 99.5% of all particles down to 0.003 micronNo ozone
IQAir GC Multigas Air FilterHyperHEPA filterNot rated, but same as other IQAir filter and covers 1,125 feetNo ozone

Sources: Consumer Reports, Association of Home Appliance Manufacturers, California Air Resources Board, product websites

Blueair (recommended, no ozone)

Blueair Blue Pure 211 (Amazon.com)

Both the Blueair Blue Pure 211 ($250) and Blueair Classic 605 ($750) ranked in the top spots on Consumer Reports’ latest guide to air purifiers. Both were found to be “especially effective at removing dust, smoke, and pollen at its highest speed,” though the Blue Pure 211 was much louder on its lowest speed than the Classic 605. However, the Classic 605 was “very noisy” at its highest speed, while the cheaper model was average noise at high speed.

Blueair Classic 605 (Amazon.com)

The Blue Pure 211 has a high annual cost because it’s not Energy Star-qualified like the Classic 605, but both had “relatively high” operating costs and filter replacement costs, according to Consumer Reports. The Blue Pure 211 has a washable pre-filter for larger particles.

Although the Blue Pure 211 technically ranked highest on Consumer Reports’ list, with a score of 89, the agency does not recommend this model. Instead, it recommends the more-expensive Classic 605, which scored an 88, in addition to recommending the next two models from Honeywell and Alen.

Honeywell (recommended, no ozone)

Honeywell HPA300 (Amazon.com)

The Honeywell HPA300, at $250, is the next-recommended air-purifier model by Consumer Reports. It scored a 76 overall and was effective at removing dust, smoke, and pollen at its lowest speed, which matters for a purifier you may use in your bedroom. It was also among the quietest air purifiers tested when running on its highest speed. It’s Energy Star-qualified and easy to carry; it comes with a carrying handle, should you need to move it from room to room. It also has a programmable timer. This model also carries high operating and filter costs, per Consumer Reports.

Alen (not recommended, ozone possible)

Alen BreatheSmart (Amazon.com)

The Alen BreatheSmart also is recommended, and the last of the brands tested to score in the 70s, with an overall score of 72. This $600 air purifier also performs well at low speed, like its competitors, and is among the quieter air purifiers running on high. However, it includes an ionizer — though Consumer Reports claims it “produces no significant ozone.” It has a carrying handle and is easy to use, but like other air purifiers, you’ll be paying for filters and relatively high operating costs.

IQAir (recommended, zero ozone)

Now a little more about Long’s baby, IQAir HealthPro Plus, which John has purchased two of for his home. (He also recommends the IQAir GC MultiGas Air Purifier for people who smoke or live close to highways.)

IQAir (Amazon.com)

According to IQAir’s website, this HEPA filtration system produces the “cleanest hospital-grade air in your room.” Its HealthPro Series is rated No. 1 for allergies and asthma, and Long says its patented HyperHEPA filtration system sets it apart. It is tested and certified to filter 99.5% of all particles down to 0.003 microns while other brands may only attack larger particles.

“Everybody else is still chasing IQAir trying to get it to clean as well as it does, but it’s 99.5% effective,” Long says. “It gets the air 100 times cleaner than the competition.”

IQAir just released a desktop model, but Long doesn’t sell it yet. He’s waiting for any bugs to be worked out and to ensure it’s not a “placebo,” like other brands’ desktop air purifiers.

Should I put an air purifier in my bedroom or living room?

Should you decide an air purifier is for you, there is a particular set-up you should use. Note again that HVAC whole-house air purifiers do not work — they can’t penetrate walls, Long says, so don’t believe any advertisements that tell you otherwise.

You’ll need an air purifier for each large room of your house that you want cleaned. The most important would be where you sleep; the next-most important is your main living area, where you spend the most time awake.

“You absolutely want to sleep under an air purifier,” Long says. “That’s the six to eight hours a person is stationary, so you want them breathing the freshest air possible to endure the next 16 hours they’re awake.”

Improving air quality without an air purifier

The EPA has some good tips to improve indoor air quality, which is where you should start before even purchasing an air purifier. This includes preventing mold by controlling moisture in your home and reducing any sort of allergy triggers. The U.S. Consumer Product Safety Commission also goes in depth on maintenance of household appliances and includes a reference guide to major indoor air pollutants in the home that is worth reviewing. It is also a good idea to try to live as far away from a major freeway as possible, as living within 500 feet of a highway can cause increased exposure to harmful chemicals like benzene.

In addition, Consumer Reports also suggests the following:

  • Vacuum often and thoroughly using a HEPA vacuum (Long says a quality vacuum and air purifier make a great team).
  • Do not smoke indoors (and we’d add, at all).
  • Make sure to change the air filters in your home and perform regular maintenance on heating/cooling equipment.
  • Cut down on your candle use — if you’re looking to relax, try essential oils or bath salts instead.
  • A fireplace also can be a big source of irritants, so cut down on its use or at the least, make sure it’s regularly cleaned.
  • Don’t forget to use an exhaust fan while cooking and in your bathroom and laundry rooms.
  • Finally, always store chemicals, solvents, glues, and pesticides away from your home.

Do you have an air purifier that works best for you in your home? Let us know in the comments!

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