Best Air Purifiers

Do Air Purifiers Really Work?

Medical experts warn that not even the very best air purifier can make any health claims, and the EPA bluntly advises that air cleaners be only part of an air treatment plan that includes controlling the source of pollutants and improving ventilation. Still, reviewers generally agree that high-performing air purifiers are worth the investment. Many consumers with allergies, respiratory problems, sensitivity to odors, and pets report an air purifier offers welcome relief in the form of improved comfort and health.

Pricey vs. Cheap Air Purifiers

The market for air purifiers is growing, with new brands and technologies emerging at a steady clip. High-end names such as IQAir, Blueair, Austin, and Alen sit well outside the budget zone with air cleaners that often start at $500 or so. In general, pricey air purifiers do a better job scrubbing the air and pushing it back out, run more quietly and efficiently, and feature more advanced filter systems than cheaper models. Some hit medical-grade air-quality standards. They often boast conveniences such as remote and smart controls and come with longer warranties.

Still, the inexpensive air purifiers highlighted on our list can hold their own. Bearing the labels of trusted household appliance brands such as Whirlpool and Hamilton Beach, along with specialty brands like Holmes, Winix, and GermGuardian, they may be short on bells and whistles, but they win endorsements from users and experts for effective and reliable performance at a value price.

Air Purifier Types

The first step in choosing an air purifier is to identify the air quality issue(s) you want to address, such as dust, pollen, chemical vapors, and so on. Some cheap air purifiers focus more on particulates than on odors or gases, and vice versa. The Environmental Protection Agency dedicates an entire section of its website to the topic of indoor air quality and the performance characteristics of different types of air cleaners.

Models that clean the air with a physical filter are the most common and arguably the most effective, especially when outfitted with a high efficiency particulate air filter. In this setup, air is pulled in by a fan and passes through a filter that traps airborne irritants. The cleaned air is circulated back into the room. HEPA filters come in several grades, or classifications, with a "true" HEPA filter capable of trapping 99.97 percent of airborne particles -- think dust, pollen, mold spores, pet dander -- as small as 0.3 microns (the average human hair is 50 microns across).

Several of our top picks boast a true HEPA filter, and anyone who suffers from severe allergies or asthma should opt for an air cleaner with the highest-grade HEPA filter. Others on our list use "HEPA-grade" filters that capture 99 percent of invisible airborne particles. Reviewers hold that some of these models are absolutely viable choices for mild or seasonal allergies.

The best air purifiers rely on multi-level filtration. Typically this involves a pre-filter that traps larger particles, like pet hair and dander, and an activated carbon filter that helps absorb odors, smoke, and volatile organic compounds emitted by draperies, carpeting, upholstery, household cleaning agents, paints, varnishes, waxes, and certain building materials, among other substances. In some models, the pre-filter and carbon filter form one unit; in others they are separate.

The number of times air flows through the filter each hour is referred to as "air changes per hour, or ACH. Many experts recommend a minimum of four, although this specification is not often reported by the manufacturer.

UV Air Purifiers

Some models, including several of our picks, also incorporate an ultraviolet light (UV-C) that's meant to destroy bacterial microorganisms as the final level of filtration. Experts note, however, that the amount of time required to do the deed is longer than the amount of time the particles are exposed to the light, thus minimizing the technology's effectiveness. Reviewers who keep an air purifier in their bedrooms often gripe that the light on some of these models is too bright for nighttime use. It can be switched on or off at the user's discretion.

Ozone Air Purifiers

The most controversial air purifiers intentionally convert air molecules into ozone to tackle odors. The EPA warns that ozone can damage the lungs and, at the very least, exacerbate respiratory problems. Consequently, many experts recommend against ozone-generating air purifiers.

Ionic Air Purifiers

Ionic air purifiers also produce small amounts of ozone, but supposedly at levels that do not exceed current safety standards. Instead of using a filter, ionic air purifiers catch contaminants on electrically charged plates/blades or cells. They send out negatively charged ions that attach to airborne particulates, which are then pulled down out of the air and lured back to a positively charged collector plate. Reports dating back to at least 2003 have questioned the efficacy of air ionizers. And yet, these types of purifiers remain popular with some consumers, at least in part because they have no fan, so they're nearly silent. But the absence of a fan also means the machine catches only contaminants that happen to drift within close range. Experts note that often the particles on the charged plates can loosen and be recirculated, and some wind up settling on other surfaces.

Our inclination is to avoid models outfitted with ionic technology unless they include other means of removing airborne irritants and offer the option of shutting it off. Several of our picks include an ionizer as an optional step in the air cleaning process.

The Winix line of air cleaners uses a proprietary PlasmaWave as the final stage in the filtering process. This technology emits both positively and negatively charged ions to combine with water vapors in the air to create oxidizers that neutralize germs, odors, vapors, and gases without emitting any ozone. Also, the charge on these plasma ions is weaker, so they dissipate more quickly, leaving less potentially harmful particles floating about in the air. The PlasmaWave function can be turned on or off.

Large vs. Small Room Air Purifiers

The next step in choosing an air cleaner is determining where you will place it, as the room's square footage affects both size and price. Small-room models intended for less than 200 square feet are always cheaper than large-room air purifiers meant for 350 square feet and up, regardless of features or performance. But a model that's too small for the space won't filter and recirculate the air into the room often enough. Many rooms straddle the line between small and large, so err on the large side when deciding on the best model for your space.

Determining which air purifier is best for your needs, especially at the lower end of the price spectrum, can be frustrating. To identify the best budget air purifiers, we turned to comments posted by users on retailer sites including Amazon, Best Buy, Home Depot, Walmart, Target, Staples, as well as manufacturers' websites. For expert advice we looked to sources including Consumer Reports, TopTenReviews, Reviews.com, Wirecutter, TechGearLab, and TechHive, which conduct testing. We also sought online advice from long-standing industry professionals on sites such as AllergyandAir.com and AchooAllergy.com.

As with many consumer products, reviewers often stake out opposing opinions: The positive experiences of many are offset by the negative experiences of others. Most users report good results with the models on our list, writing that they leave the air feeling and smelling clean and fresh, even in the presence of multiple pets. Still, each gets dinged by some reviewers as a total waste of money. Other common complaints include excessive noise from the fan, the cost of replacement filters, and the demands of maintenance (the filters need frequent cleaning).

Pollutant Removal

Judging the performance of an air purifier starts with the simple question of whether or not it cleans the air. Reviews of our top picks say they handily vanquish the usual airborne irritants and also seem to have good staying power. Users report noticeable differences in dust levels and credit their air purifiers with mitigating sneezing, coughing, and wheezing in humans and animals alike. Our favorite air cleaners also are lauded for reducing pet and cooking odors, alleviating the smoke and smell from cigarettes and cigars, ingesting the floating detritus of construction projects, and for clearing the indoor air in the aftermath of wildfires. For models with an air quality indicator, hard evidence comes in the form of lower readouts, users write.

Keep in mind, however, that airborne particles often settle before being drawn into an air purifier, so even a true HEPA filter sandwiched between other layers of filtration won't eliminate all airborne pollutants. For best results, place the unit away from walls and obstructions, in a spot where the air can circulate freely.

CADR

The "clean air delivery rate" indicates how much air is circulated back into a room following the filtering process. This measure should correlate with the size of the room(s) where the air purifier will be used. The CADR is calculated for three types of pollutants: tobacco smoke, pollen, and dust. Each is determined separately by the Association of Home Appliance Manufacturers, an independent third party, as part of a voluntary program. The numbers, which indicate the cubic feet per minute (cfm) that the unit can clear, generally are listed on the packaging for participating products. Note that some manufacturers specify one combined number only.

The maximum CADRs, based on the testing protocols, are 400 for dust and 450 for pollen and smoke. AHAM recommends looking for a CADR for tobacco smoke that's at least two-thirds the square footage of the room where the air purifier will be used. An air purifier with a higher CADR relative to the room size will clean the air faster and more often.

Noise Level

One important thing to remember about noise is that one person's white noise is another person's distraction. Most air purifiers have at least three speed settings. The faster the fan whirs, the noisier it gets. Users report that the lowest setting is the least intrusive, although this reduces the rate at which air is circulated. Some budget models are equipped with a sleep mode that reduces nearly all noise, and some are equipped with a turbo setting that ramps up the action for rapid cleaning.

Ongoing Expenses and Maintenance

It would be ideal if an air purifier could be purchased, plugged in, and left alone. Much to the chagrin of reviewers, many air purifiers demand two ongoing expenses: energy and, more significantly, replacement filters.

To cut the energy cost, which corresponds to the size of the air purifier and the frequency with which it's used, experts recommend using the lowest setting and leaving the machine off when you don't need it. Closing the windows and doors to the room being refreshed also helps concentrate the cleaning power. Air cleaners designed for midsize and large rooms are often Energy Star certified, indicating they are at least 40 percent more efficient than models lacking the certification.

On most air purifiers, both the primary filter and the (carbon) pre-filter must be vacuumed frequently and replaced on schedule. Occasionally the pre-filter can be washed in between replacements, and a few air purifiers use a permanent HEPA or pre-filter that requires only regular cleaning. The HEPA filters on other room air purifiers should be changed at least every 12 to 18 months, and some users report replacing them as often as every three months. The pre- and carbon filters usually last three to six months. Some models feature indicator lights or a replacement timer to remind users when filters are due for a change.

Depending on the specific size and model, and the type of filter (pre-filter, carbon, HEPA), the cost of a replacement ranges between $15 and $80, give or take a few dollars. Make sure to follow the manufacturer's guidelines for filter maintenance and replacement (most models take proprietary filters only). Failure to do so will limit the unit's effectiveness and longevity.