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Smart Home

What is an air purifier? Everything you need to know

We sort out these cleaning machines and clear the air on why you might want one in your home.


Dyson's line of air purifying fans control air pollutants in style.  

Sarah Tew/CNET

If your home is feeling dusty, moldy or just kind of funky, there are several small appliances ready to come to the rescue. Dehumidifiers and humidifiers mediate the moisture in your home, solving a host of climate issues and problems like mold growth. Air purifiers, sometimes referred to as air cleaners, also work to keep your home's climate healthy by removing polluting particles like dust and pollen. Often packaged as portable units and fans, here's how these cleaning machines help you breathe easier. 

What does it do? 

Portable air purifiers remove pollutants from the air. Indoor air pollutants fall into three main categories: 

  • Particulate matter. This includes biological pollutants like molds, dust mites, bacteria, animal dander and viruses.
  • Gaseous pollutants. Things like paints, varnishes, adhesives and pesticides.

Air purifiers work to filter these contaminants out of your air.  Anyone sensitive to allergens or with asthmatic symptoms might benefit from an air purifier. Of course, it's hard to imagine anyone who wouldn't be better off with a cleaner atmosphere inside their home, and air purifiers can certainly play a helpful role.


Vacuuming your home regularly is a good way to stay ahead of accumulating dust and allergens.

Colin West McDonald/CNET

However, an air purifier isn't a replacement for keeping your home clean and ventilating it when possible. The most effective way to manage pollutants in your air is to avoid introducing them in the first place. Preventive measures like not smoking indoors, vacuuming regularly, allowing fresh air in on occasion and keeping solid surfaces sanitized are still the best ways to combat indoor air issues.  

How do air purifiers work? 

Air purifiers remove these pollutants from the air using one of three common methods: filtration, electrostatic precipitation and ionizing. The EPA warns about the risk of ozone created by some electrostatic and ionizing air purifiers. Using a filter-based air purifier is widely considered the healthiest and most effective option. That's the method we'll focus on here. 

The most effective form of air filtration (and likely the one you've heard the most about) is a HEPA (high-efficiency particulate absorber) filter. Models with filters pull in your home's air and move it through the filter with a circulating fan. When the air moves through each filter, any pollutants and particles are caught in the filter. The clean air is then pushed back out into your space. HEPA filters do a better job here than a standard filter because they can catch finer particles. 

Buying tips

Air purifiers range from under $100 to well over $1,000, and the major difference is typically the quality of the air or the amount of air (how big a space) it is able to effectively purify. Most models are designed to sit on the floor, but you can find tabletop models and even wall-mounted designs. Read the descriptions carefully to be sure you get a purifier big enough to fit your room, but remember that a larger model will likely also use more energy. 

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You might see the abbreviation and value for "CADR" on an air purifier's packaging, which stands for "clean air delivery rate." That's a measure of how quickly the purifier can deliver clean air. The higher the CADR, the more quickly the air purifier can filter your air, though some manufacturers have suggested this lab testing method isn't an accurate simulation of an average home. Dyson even came up with their own testing method, called the Polar test. Another way air purifier efficiency is measured is with by  MERV (minimum efficiency reporting value), where the lowest rating is 1 and the highest is 20. HEPA filters rate between 17 and 20. Here are a few notable options available on Amazon: 

If dust, allergens and other pollutants are taking over your home, try a good deep clean and consider an air filter for those extra irritating spaces. 

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