Air purifiers are certainly a luxury, but they’re a luxury you can’t afford to skip or neglect. Even if your home isn’t as polluted as the outdoors, and even if you go to great lengths to keep your indoor environment spotless, you can absolutely benefit from having one.


Yes, air purifiers can be pricey. And yes, they aren’t so crucial that you need to go out and buy one right now. You can put it off for a while if necessary, but we highly recommend getting one sooner rather than later. The benefits are real and you’ll kick yourself for putting it off.

The Benefits of an Air Purifier

An air purifier is a device that pulls in air from its surrounding environment, extracts certain kinds of particles from that air, and then recirculates it back into the environment. Don’t confuse it with a dehumidifier, which pulls moisture out of the air instead (see our dehumidifier guide for more on that).


So what kinds of particles can be removed from the air?

  • Pollen: During Spring and Fall, plants release pollen. Pollen can enter your home through open windows or by hitching a ride on your clothes. If you’re allergic, pollen can turn your home from a place of comfort into a place of irritation.
  • Pets: Cats and dogs can leave dander and fur on furniture, which get kicked into the air every time you sit down or stand up. Dusty cat litter can also contaminate the air.
  • Dust: No matter how well you clean, there will always be dust in the air. And every time you clean your shelves, desks, stands, etc., dust gets kicked back up. Dust can irritate the lungs, and dust mites can cause skin irritation.
  • Mold: Mold can grow in damp areas and spread through normal air circulation. Not all kinds of mold are deadly, but many can still cause breathing issues.
  • Odors: Pungent and overwhelming smells are caused by odor molecules. By pulling them out of the air, you can freshen up the overall smell of your home. This is especially true for food (e.g. curry, chili, stews) and cigarette smoke.

If you aren’t sure whether or not you’d benefit from an air purifier, you can get one of these indoor air quality monitors that’ll alert you when problems arise. Then again, you may want to start purifying your air right now to preemptively avoid such problems in the first place.

Not all air purifiers extract the same kinds of particles though, and not all air purifiers are effective to the same degree. Let’s look at what you need to know before buying one.

What to Look for in an Air Purifier

Filtration Type

There are five main types of air purification technologies:

  1. HEPA (High-Efficiency Particulate Air): Extremely effective because it can extract particles as small as 0.3 microns, including dust and allergens, but aren’t effective for eliminating odors. HEPA filters should be replaced annually, preferably twice a year.
  2. Carbon: Great for general use and purification, effective for removing odors, chemicals, and smoke. The activated carbon bonds to particles as they pass through. Unfortunately, ineffective for allergens, mold, and bacteria.
  3. Ozone: Great for removing odors in the air, but ineffective for extracting particles like allergens. The EPA states that ozone gas can cause respiratory issues when breathed in, so regular use is discouraged.
  4. Electrostatic (Ionic): The most effective because it can extract particles as small as 0.1 microns, but doesn’t work on odors. Unfortunately, electrostatic purifiers produce ozone gas as a byproduct, which can cause respiratory issues when breathed in.
  5. UV (Ultraviolet): Very good for purifying live contaminants, including mold, mildew, fungus, bacteria, and even some viruses. Completely ineffective for non-living pollutants like smoke, allergens, dust, and odors.

Clean Air Delivery Rate (CADR)

The clean air delivery rate is a measurement of how quickly the purifier can clean the air. It’s actually comprised of three different ratings depending on particulate type:

  • Smoke (10 to 450)

  • Dust (10 to 400)

  • Pollen (25 to 450)

The measurements are in cubic feet per minute. In other words, the CADR rating shows how much clean air it can deliver in a certain amount of time. The higher the CADR rating, the more “clean air” gets added to your room every minute. CADR ratings are expressed in the form of 300/200/200 — first smoke, then dust, then pollen.

Note that CADR ratings are only reliable when certified by AHAM (Association of Home Appliance Manufacturers). If a purifier isn’t AHAM-certified, you should not trust its CADR rating because it hasn’t been independently verified.

Air Changes per Hour (ACH)

The air changes per hour describes how many times the purifier can clean the entire volume of air in a room every hour. This is calculated using the purifier’s CADR rating and the size of the room it will be in.

For example, consider a purifier that has a CADR rating of 450 for smoke (that’s cubic feet per minute) in a 300 sq. ft. room with 8 ft. walls. Multiply 450 by 60 to get 27,000 cubic feet cleaned per hour. Multiply the room’s square footage by its wall height to get 2,400 cubic feet. Divide 27,000 by 2,400 to get 11.25 air changes per hour for smoke.

This means the purifier in the example would clean the entire room’s air just over 11 times every hour. A higher ACH means cleaner overall air.

You should never buy a purifier that has an ACH lower than 4 because it won’t be effective enough. If you know your room’s total volume, use the formula below to find the minimum CADR needed to reach an ACH of 4. Replace 4 with a higher ACH if you want:

Minimum CADR = (4 x [Room Volume]) / 60

Noise Level

Since air purifiers need to run all the time, the noise level is one of the most important quality-of-life considerations to make. Most people aren’t willing to sacrifice peace and quiet for cleaner air, and there’s no point in cheaping out on a loud purifier if you end up never using it because it drives you crazy.

Air purifiers don’t have a standard noise rating, so our recommendation is to opt for a larger model and run it at its lowest speed rather than buying a smaller model and running it at its highest speed. This means a higher upfront cost, but sanity and peace in the long run.

Best Value Air Purifier: Honeywell HPA300

The AHAM-certified Honeywell HPA300 has a CADR rating of 300/320/300 and is recommended for large rooms up to 465 sq. ft. It uses HEPA filters, has four cleaning levels (General, Germ, Allergen, and Turbo), and an automatic shutoff function that you can set for 2, 4, or 8 hours. It’s ugly but it works well and provides great value.

Runner-Up Air Purifier: Coway AP-1512HH

The AHAM-certified Coway AP-1512HH has a CADR rating of 233/246/240 and is recommended for medium rooms up to 361 sq. ft. It has a pre-filter (so you don’t have to change the HEPA filter as often), three speed settings, air quality indicator, filter replacement indicator, and quieter-than-normal operation.

Budget Air Purifier: Winix 5300-2

The AHAM-certified Winix 5300-2 has a CADR rating of 232/243/246 and is recommended for medium rooms up to 360 sq. ft. It has a pre-filter (to prolong the life of the HEPA filter) and uses both HEPA and carbon filters to clean the air. It’s equipped with a smart indicator that senses air quality and adjusts the speed accordingly.

Other Ways to Improve Your Home

There’s more to do with indoor air quality than just filtration and purification. We recommend checking out these indoor air quality boosting devices if you really need extra help with keeping your home nice and clean.

We also recommend keeping tabs on temperature and humidity, both of which can have adverse effects on health if left unchecked. See our articles on the benefits of monitoring temperature and humidity, smart thermostats that save you money, and gadgets to keep you warm and happy in the winter.

What’s your biggest concern when it comes to air quality? Got any other tips we missed? Let us know in the comments below!

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