By Glenda Taylor and Jamie Birdwell Branson | Updated Sep 28, 2021 12:25 PM

A. Sorry to hear about your allergies. Allergic rhinitis (commonly known as hay fever), as well as allergies to pet dander, smoke, and/or dust, can make you feel as miserable as you do with a common cold—but one you can’t seem to shake (because, alas, there’s no cure for allergies). No wonder the constant sneezing, wheezing, and itchy, watery eyes have you seeking solutions!

Seasonal allergies can also be problematic for those who suffer from asthma, and exposure to increased pollen levels and other allergens can cause flare-ups. The answer to your question, “Do air purifiers work?”, ultimately depends on the type and quality of purifier you choose and whether you take other steps to eradicate allergens in the home.

Fortunately, whether your suffering is due to pollen in the air or your boyfriend’s cat sitting on your lap, an air purifier may provide you with some relief. Here’s how these handy little appliances can make living with allergies a bit more bearable.

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An air purifier is a small device designed to remove such airborne contaminants as pet dander, smoke, and dust. According to the Environmental Protection Agency (EPA), a portable air cleaner is one of the most effective ways to improve the indoor air quality in a single room or area. However, no matter the quality of the air purifier you buy, no model in the world can banish all of the pollutants in your home.

Here’s how an air purifier works: Air gets sucked into the device via an internal fan system and is then passed along to the filter inside. The filter traps airborne pollutants like dust, and then a fan pushes clean air out into the room. There are two basic types of air filters in air purifiers: One eliminates particles and one removes gases—some of these even purport to remove volatile organic compounds (VOCs).

If you want an air purifier to remove particles like dust, dirt, and soot, check the packaging or product description for a clean air delivery rate (CADR). The higher the CADR, the better the purifier is at trapping particles. Another sign of an effective air purifier is the use of a high-efficiency particulate air (HEPA) filter. An air purifier with a HEPA filter is likely to have a relatively high CADR. Filters themselves also have ratings. One acronym that often appears on filters is the MERV rating, which stands for minimum efficiency reporting value. For filters used in residential air purifiers, MERV ratings range from about 7 to 12, with the higher number indicating more effective pollutant trapping.

You never know just how contaminated the air inside your home is until you use an air purifier and see the particles collected on the filter. Depending on the model you own, you can just pop off the back panel to take a peek inside at the filter. Filters generally need to be changed about twice a year, or whenever the filter looks completely full.

But will you feel any different? Hopefully, yes—and perhaps in more ways than one. A small-scale study in China found that air purifiers reduced fine particulate matter in the air (dust, pollen, dander) and improved participants’ blood pressure levels and lung function.

If you’re not feeling a positive effect on your allergy symptoms after using an air purifier for a month or two, you might want to reevaluate its placement in the room (maybe moving it closer to your bed or couch or further away from a door or window). If you notice an improvement at first only to have it wane, remember to check the filter to see if it needs to be changed.

Some people are allergic to household mold (often caused by water damage inside the home), with some symptoms similar to those triggered by seasonal, dust, and animal dander allergies. Unfortunately, air purifiers aren’t designed to remove mold, nor can the devices eliminate the musty odors associated with mold. To solve the problem, investigate and repair the source of any water damage and then contact a mold remediation service. These professionals use antimicrobial agents to remove mold.

If routine allergies or asthma symptoms negatively impact your life, the evidence that a HEPA filter improves respiratory health may encourage you to shop around for an air purifier. The best air purifiers generally cost between $200 and $900 on the high end, but since it’s recommended to run them constantly, expect a spike in your electricity bill. Though some devices are more energy-efficient than others, the average HEPA air purifier will consume 50 to 200 watts of electricity and run you an extra $30 to $90 annually to keep it plugged in and working. If you’re concerned about your bottom line, look for the blue Energy Star sticker when shopping to take home a certified model that uses 40 percent less energy to operate.

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An air purifier draws in air, traps pollutants, and then emits the cleaned air back into the room. Still, every time you walk across the floor, your feet can stir up more particulates from the carpet, sending them airborne, and each time you sit on an upholstered sofa or open the curtains, more particles can be released into the air. To cut down on the amount of airborne particles and other allergy triggers, it’s important to keep them from getting into the house in the first place and to remove those that are already in the home. Here are a few recommended strategies for doing this:

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Wood-burning fireplaces, pies that bubble over during baking, and even burning candles can all create smoke in the home that can trigger allergy symptoms. Air purifiers can remove smoke from the air, but it takes time, and some are better at the task than others. While a HEPA filter will trap airborne ash, to remove the smell of smoke, look for an air purifier that contains an activated carbon filter.

As the name implies, activated charcoal is the main ingredient in an activated carbon filter. This type of filter can absorb smoky smells as well as volatile organic chemicals (VOCs) that are hazardous to breathe. The quality of the carbon filter will determine how effective it is at trapping smoke, VOCs, and odors. For the best overall results, select an air purifier that uses an activated carbon filter in combination with other filters, such as a HEPA filter.

For effective smoke removal, the Association of Home Appliance Manufacturers (AHAM) suggests that the CADR of an air purifier should be equal to—or exceed—2/3 of the room’s square footage.

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Air purifiers are labeled to indicate the size of the room in which they can be effectively used. Typically, the packaging will provide a maximum square footage rating, or specify that the air purifier is suitable for a small, medium, or large room. When in doubt, go up a size.

Like smoke, odors can be eliminated by using an air purifier with an activated carbon filter. The charcoal in the filter absorbs distasteful smells like those of body odor, litter boxes, and cooking fish. But make sure your air purifier also has a HEPA filter to deal with particles—a carbon filter alone will not trap dust or pollen.

Don’t expect immediate results, however. It takes time for all of the air in the room to circulate through the purifier, so odors can linger for an hour or so. The cleaner’s CADR number and the size of the room will determine how quickly an air purifier can freshen a room and remove odors. When you’re determining the appropriate CADR for a room, be sure to take the ceiling height into consideration. If the ceiling is over 8 feet high, move up to an air purifier with the next highest CADR rating.

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An air purifier is only as good as its filters. When they become clogged, the unit can’t operate effectively. Change the filters as recommended by the manufacturer. To make this easier, many air purifiers have indicator lights to signal that it’s time to replace the filter.

Some air purifiers are equipped with washable HEPA filters. Though some manufacturers do not recommend it, you may still be able to wash a HEPA filter and reuse it—they’re pricey, after all—at least until you can order a new one. To wash a HEPA filter, make sure the unit is unplugged before completing these steps:

1.    Remove the filter from the air purifier. This usually involves opening a grille on the purifier and lifting the filter out.

2.    Fill a sink basin with warm water and add a squirt of liquid dish soap.

3.    Submerge the filter in the water and let it soak for 10 minutes.

4.    Carefully rinse away dirt using a light spray.

5.    Set the filter aside to dry completely. This could take anywhere from a couple of hours to overnight.

6.    Vacuum the grilles on the air purifier to remove built-up dust before putting the dry filter back in the unit.

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