Smart air purifiers can help you pay close attention to indoor air quality and make breathing easier. From HEPA filtration to ion technology, we help you understand your options and choose the best networked air purifier based on your needs and budget.

Between allergies, COVID-19 and wildfires, there are many reasons to worry about the quality of the air you breathe. Since these problems are more prominent than ever before, it is no wonder that the demand for air purifiers continues to increase. 

High-quality air purifiers can remove bacteria, dust, industrial emissions, mold, odor, pet dander, pollen, viruses and other pollutants in the air. But not all air purifiers are the same. With so many eye-catching models on the market, it is difficult to narrow your choice. In the past year, PCMag has prioritized testing various smart air purifiers to help you choose the product that best suits your needs and budget. (We even tested the Razer Zephyr, a "wearable air purifier," which is actually just a high-tech mask.)

Personally, my interest in air purifiers began in the fall of 2019 shortly after I adopted Bradley the Pitbull in the fall of 2019. Not long after he was adopted, my allergies turned into asthma. In desperate relief, I bought the refurbished Dyson Pure Cool Link TP02 on eBay during the Black Friday sale. My refurbished machine works like new, and although I can't say that it cured my asthma and allergies alone, it helped reduce my symptoms (as well as medication and daily vacuuming). 

Since then, I have purchased a large number of smart air purifiers from various brands for testing and review. I still take Xyzal allergy medicine every day, but I haven't had an asthma attack or have to use my salbutamol inhaler for more than a year. I tell you this is a testament to electric air purifiers (as well as robotic vacuum cleaners and modern medicine). 

If you want to improve indoor air quality, a good purifier is essential. But before investing, please read on some important factors to consider. 

Most air purifiers (not just smart purifiers) usually have sensors to measure the density of various air pollutants, such as nitrogen dioxide (NO2, a toxic gas mainly produced by car exhaust and power plants), PM2 .5 (particulate matter smaller than 2.5 microns) size, including industrial emissions and tobacco smoke), PM10 (particulate matter up to 10 microns, including dust, mold and pollen) and VOC (volatile organic compounds, or from items such as cleaning products and paint Potentially harmful gases). 

Smart air purifiers usually have Wi-Fi for phone and/or voice control, and collect information about the above-mentioned pollutants and send it to a companion app, where you can monitor the air quality in your home. Some apps provide a graph of your air quality over time. Dyson broke it down by pollutant and showed a chart for each pollutant. 

Most smart air purifiers have an automatic mode that can automatically adjust the fan speed of the machine according to the degree of pollution detected. They usually also allow you to set up an air purification plan so that the machine automatically turns on and off at the time you specify. Some models support Amazon Alexa, Google Assistant, and Apple Siri, so you can control them using voice commands. 

Some indoor air pollution sources are obvious, such as cigarette smoke, household cleaning products, and pet dander. Others are not. 

The U.S. Environmental Protection Agency (EPA) stated that "thousands" of products-including air fresheners, dry cleaning clothes, and office equipment such as copiers and printers-emit volatile organic compounds, which can cause a range of health effects. From headache to cancer. In addition, the concentration of indoor VOCs is usually much higher than outdoors. 

Anything that produces smoke—such as cooking, burning candles or incense, or lighting a fireplace—will cause the concentration of particulate matter to increase. The EPA says that PM10 and smaller PM10 can "deep into your lungs" and in some cases also enter your blood. Inhalable particulate matter, especially PM2.5, is 30 times thinner than the average human hair, and may pose a greater risk to people with heart and lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), congestive heart failure and coronary arteries disease. Most smart air purifiers can detect PM10 and PM2.5, but LG's PuriCare 360, which sells for $1,299, is the only model in this list that reports the density of PM1.0 (particulate matter 1 micron or smaller). 

Humidifiers can help relieve chapped lips and dry skin, but if you accidentally use distilled water and clean them frequently, they can provide a fertile breeding ground for bacteria and mold, which can then be sucked into the air. Gas stoves, especially when poorly ventilated, emit unsafe levels of nitrogen dioxide, which can stimulate the respiratory system and aggravate or promote the development of asthma. 

Another gas pollutant to worry about, especially when you decorate or redecorate your house, is formaldehyde. Many household items will release formaldehyde, such as carpets, floors, furniture, carpets, insulation materials, particleboard, plywood, paint, varnish and wallpaper. Long-term exposure to low concentrations of formaldehyde can cause inflammation of the skin, eyes, nose and throat. Higher levels can cause certain types of cancer. 

Dyson said that formaldehyde is 500 times smaller than 0.1 micron, so it is difficult to capture. Not all air purifiers can detect and decompose formaldehyde (Dyson charges more than $100 for models that can detect and decompose), so you need to consider this when considering your options. Check out our personal reviews to learn about the pollutants detected and captured by each model. 

In some cases, exposure to air pollutants may not cause symptoms immediately, but it may cause serious health problems. For this reason, the U.S. Environmental Protection Agency stated that "even if the symptoms are not obvious, we must carefully try to improve the indoor air quality in the home."

Buying an air purifier is not the only way to improve indoor air quality. Other measures you can take include eliminating sources of air pollution, opening windows (as long as the outdoor air quality is good), and regularly vacuuming and dusting surfaces. 

The machines on this list use high-efficiency particulate air (HEPA) filters, activated carbon filters, ion technology, and/or ultraviolet light to combat air pollutants. 

HEPA air purifiers are the most popular and account for the largest part of the market. To comply with current benchmark standards, HEPA filters have been tested and certified to remove at least 99.97% of dust, pollen, mold, bacteria and any other airborne particles as small as 0.3 microns. There are different levels of HEPA filters, but in general, you need to make sure that the model you buy meets the baseline standard (many models are labeled "True HEPA") and stay away from products that are labeled as "HEPA-like", "HEPA type" "Or "HEPA type", this may not be so effective. 

As Wirecutter reported late last year, a NASA study found that HEPA filters can actually capture almost 100% of particles as small as 0.01 microns (10 nanometers), far exceeding the baseline standard. From this perspective, COVID-19 is approximately 60 to 140 nanometers. H1N1 flu is about 80 to 120 nanometers. 

At the same time, the activated carbon filter is filled with porous carbon, which can capture gases such as NO2 and VOC and bad odors from the air. Activated carbon filters are usually used in combination with HEPA filters that do not remove gas.

Our first choice, the $549.99 Dyson Purifier Cool TP07, is equipped with a 360-degree filter with a HEPA layer that captures allergens, bacteria, mold spores, pollen and other pollutants, and an activated carbon layer that removes gases and odors. It also doubles as a swing fan. The version that destroys formaldehyde, called the purifier cool formaldehyde TP09, is priced at $649.99. Dyson said that its latest air purifiers, including TP07 and TP09, not only meet the baseline HEPA filter standard, but are also completely sealed to the HEPA H13 standard, which means they can remove 99.95% of particles as small as 0.1 micron.

LG PuriCare 360​​ is another model that combines HEPA and activated carbon. The only disadvantage of the HEPA and activated carbon models is that replacing the filter can be expensive (approximately $50 to $100) and wasteful.  

Other models, such as Sharp FXJ80UW and Aura Air, combine HEPA, activated carbon and ion technology. Sharp’s model has an ion generating device that uses water and oxygen molecules in the air to generate positively and negatively charged ions and disperse them throughout the room. Then, these ions will actively attach and decompose pollutants in the air, such as bacteria, molds and viruses, and then return to the air in the form of invisible water vapor. Sharp said that this technology reduced 94% of E. coli, up to 87.7% of mold and 90.3% of MS2 virus in a closed laboratory within four hours. Aura Air's patented sterilizer disinfection technology works in a similar way. 

The main problem with ionic air purifiers is that they may produce ozone gas molecules, a lung irritant that can exacerbate asthma symptoms and cause many other health problems. The safety of ionic air purifiers was questioned in the mid-2000s because the Sharper Image Ionic Breeze air purifier, which was popular at the time, produced ozone (a problem that eventually led to the company's bankruptcy). 

As the California Air Resources Board (CARB) warned, some ozone-producing devices are still sold as air purifiers. The Clean Air Agency maintains a list of potentially dangerous models for avoidance. 

All models in our list that use ion technology meet EPA standards, CARB certification, and are considered safe for long-term use at home.

Dyson Pure Humidify+Cool is unique in that it can be used as an air purifier, fan and humidifier. Remember when I mentioned that humidifiers can release bacteria and mold into the air? Dyson's model solves this problem by combining UV-C light and silver mesh. A column in the water tank uses UV-C light to denature its DNA to kill aquatic bacteria so that they no longer multiply. Dyson said the system can kill 99.9% of water-borne bacteria during the first pass. As a second line of defense, the machine's 3D Air-Mesh evaporator (the part that converts the treated water into steam) has interwoven silver threads, which Dyson claims provides biological static properties that inhibit bacterial growth.

Except for Dyson, most smart air purifier manufacturers will tell you the maximum room size that their machine can effectively clean. A Dyson spokesperson stated that the company’s latest air purifier is “designed to clean all rooms-it’s just how long it takes (the larger the room, the longer it takes for the purified air to reach every corner).” In other words, Dyson tested its Pure Cool purifying fans to ensure that they can circulate purified air in a 290 square foot space (about the size of a large living room). 

LG PuriCare 360​​ is equipped with two large 360-degree HEPA filters and is recommended for rooms up to 512 square feet. In the test, PuriCare 360​​ purifies the air faster than Dyson Pure Humidify+Cool, so although it is definitely one of the more expensive smart air purifiers you can buy, it is also one of the more effective.

LG said that the fan of PuriCare 360​​ can push the purified air up to 24 feet away. Its lower part blows out purified air 19 inches from the ground, which is good for babies and children.

Sharp FXJ80UW is recommended for rooms below 502 square feet and is another great choice for large rooms. Once during a test, I accidentally burned toast, and FXJ80UW sensed smoke from another room. Its air quality monitoring light turns red, and the machine automatically increases the fan speed.

In my single-story house of approximately 1,000 square feet, most smart air purifiers I have tested can even detect elevated air pollution levels from a few rooms outside. Sometimes, when I was frying vegetables in the kitchen, the Dyson TP07 located across from my office house would detect cooking smoke that I didn't even notice, and start automatically. 

According to the US Environmental Protection Agency, there is still some controversy whether air purifiers can really reduce allergies caused by larger particles such as pollen, dust, mold and animal dander. 

The EPA said: "Most of these particles reside where they fall on the surface of the home, not in the air." "Unless they are disturbed and resuspended in the air, they cannot be removed by air purifiers."

Before using an air purifier to relieve allergies, please consider your type of allergies. Compared with other types of allergens, air purifiers may be better at catching pet dander. According to the American Lung Association, pet allergens "suspend in the air for a long time, much longer than allergens from cockroaches or dust mites." On the other hand, dust mites “attach to particles that are too heavy to stay in the air for a long time” and fall into pillows, bedding, furniture and other items “within a few minutes”. 

In my experience, air purifiers are not a panacea for pet allergies, but they certainly help. To eliminate my dog's dander, I usually keep at least one air purifier running 24/7. I find that blowing clean air on me at night is especially helpful because my symptoms often get worse. 

My allergic asthma is now under control, and my doctor allowed me to stop trying my montelukast prescription. I have stopped the medication for several months and have not experienced any asthma. Needless to say, I am a big fan of air purifiers and plan to continue using and testing new models for the foreseeable future. 

Going forward, I will continue to update this list as we review new models that we think are worth including. At the same time, if you want to view any specific smart air purifier, please let us know in the comments. 

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Angela is a smart home and wearable device analyst for PCMag. She previously worked as a PCMag reporter for eight years. Prior to that, she was a reporter for SC Magazine, covering hackers and computer security. She has also written for several newspapers, including the North Valley Suburbs in New Jersey, the Dominion Post in West Virginia, and the Union Town Herald in Pennsylvania. She graduated from the Perely Isaac Reed School of Journalism at West Virginia University.

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