We don’t have an indoor air quality law. Are air purifiers the solution?

The howling winds are unlike anything I’ve heard before as they hit the windows. The sky is a strange gray – not from the clouds, but from the smoke. A massive forest fire is raging nearby. Disaster is imminent.

In our second-floor apartment, my partner and I pack our most essential belongings and a few precious possessions. We tape the seals of our windows to prevent smoke and ash from seeping inside and keep our eyes glued to a map of the fire’s spread.

The increasing stress and deteriorating air quality are too much. We head south to a hotel, where we stay until the fire is better contained. Even there we see ash raining from the sky.

I live in Pasadena, and my apartment was just outside the evacuation zone for the Eaton Fire, which killed 19 people and destroyed more than 9,400 structures in January 2025. That month, the Eaton and Palisades fires raged simultaneously in Southern California, becoming the second and third most destructive wildfires in state history.

We were lucky, because the spread of the fire stopped five miles from our apartment. While many lost their homes, we were able to regain ours. Yet our sealed windows didn’t stop ash and smoke from seeping through the cracks and covering everything in our apartment.

With unhealthy outdoor air quality, we couldn’t open the windows for fresh air, so we relied on our air purifier. At the time we only had one in our living room. We have since added another one to our room, as well as two air quality monitors in each zone.

The atmospheric dangers have not gone away: as I write this article, smoke from a Boyle Heights warehouse fire is blowing toward us, making opening windows once again inadvisable.

Fires are a major contributor to poor air quality, but they are not the only ones. Power plants burning fossil fuels release pollutants, as do exhaust fumes from highways and city streets. There’s a reason why the weather apps on our phones report the Air Quality Index, or AQI, every day. And while overall outdoor air quality in the United States has improved over the decades, it has not improved everywhere, particularly in communities of color.

We also face indoor respiratory hazards, from gas appliances and furnaces to myriad household chemicals and off-gassing from furniture and other belongings. Outdoor air pollution creeps indoors.

As a health and wellness writer for 12 years, I’ve often seen concerns about health risks from the air we breathe 12 to 20 times a minute take a back seat to more tangible human needs, such as crystal clear water And foods free from contaminants. But there are simple steps we can take to improve the air quality in our homes.

Air purifiers can protect our airways from certain contaminants, like CNET Labs foundbut they are not the best or only line of defense against poor air quality.

Are air purifiers the breath of fresh air we need?

Air purifiers look a lot like speakers: rectangular or cylindrical electronic devices less than 3 feet tall, with perforated metal or plastic housings. You’ll usually find them on the floor or on a table in high-traffic areas like the bedroom, living room, or kitchen. Air purifier prices can range from $50 to $1,000.

I didn’t grow up in a house with air purifiers, but my mother now has two in her suburban New York home. She relied on her HVAC system’s filter, but when COVID-19 cases increased during the pandemic, she invested in air purifiers.

Experts from air-handling technology companies like Dyson, Blueair, Airthings, Coway, and Oransi all tell me they’ve seen sales of air purifiers increase during events that raise concerns about the impact of what’s in our air on our health. Think about the COVID-19 pandemic, wildfires, smoggy days of urban pollution and allergy season.

My colleague Tara Brown, CNET’s social media manager, recently purchased her first air purifier. It wasn’t technology she had grown up with, and at first it seemed like a luxury item.

“My mother’s way of dealing with a dusty house was to open the windows when cleaning, and during pollen season we tried to keep the windows closed and take allergy pills daily,” says Brown, who lives in the East Coast suburbs. “As I get older and now have my own money, I would like to try one because I am allergic to dust and pollen.”

It turns out that Brown’s mother was right to open the windows in her house. As I learned, this is the second step to take to remedy poor air quality, even before turning on an air purifier.

The first two steps to purifying the air

Your first line of defense is to focus on controlling the source of pollution.

“In cities, the largest source of volatile organic compounds used to be vehicles, but vehicles have become cleaner, and over time it now appears that the largest source is actually the substances we use in our residences,” Linsey Marr, a distinguished professor in Virginia Tech’s department of civil and environmental engineering, told me.

This includes common goods like shampoo, lotion, hairspray, deodorant, cleaning supplies and paints.

If you’re looking for low-cost or no-cost methods to control VOCs, Brigit Hirsch, press secretary for the U.S. Environmental Protection Agency, recommends carefully following product instructions to ensure you’re not using more than recommended and to determine what type of ventilation is required. If you’re painting the walls, for example, you should keep your windows open.

As for gaseous and particulate pollution released when you cook on the stove or in the oven, turn on your hood to evacuate it. If your range exhausts air outside, avoid using it on days when outdoor air pollution is high. Instead, an air purifier near the stove can help trap these cooking particles and, if it has an activated carbon filter, some gases.

To remove particles from surfaces before they are disturbed and end up in the air, vacuum regularly with a filtered vacuum cleaner and dust with a damp cloth. To dampen this cloth, use low-toxic cleaners, such as soap and water, that do not contain ammonia or chlorine, which can deteriorate air quality.

“The most important thing to do about air pollution is source control, so let’s reduce the sources that cause pollution first and foremost,” Glory Dolphin Hammes, CEO of IQAir North America, told me. IQAir is the world’s largest free, real-time air quality monitoring platform and also sells air purifiers.

Once you’ve exhausted your source control options, it’s time to vent. To prevent pollutants from building up indoors, open your windows, turn on kitchen or bathroom fans that exhaust air outside, and use window or attic fans.

When ventilation is not an option due to heavy outdoor air pollution, such as during a wildfire or during rush hour if you live near a busy road, you will want to focus on air purification.

HVAC vs air purifier: who is your ally when it comes to air?

You may be surprised to learn, as I was, that your HVAC filters were originally designed to protect the system’s heating and cooling coils, not human health.

On top of that, Theresa Pistochini, co-director of engineering at the UC Davis Energy Efficiency Institute and the Western Cooling Efficiency Center, tells me that to save energy, home HVAC systems typically only turn on when the air is being heated or cooled, so the fan isn’t constantly running. This means it doesn’t filter your air all the time, and even when it does, you may not have the highest quality filter.

You’ll want to pay attention to MERV, which stands for Minimum Efficiency Reporting Value and is based on a testing method developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers. While most people buy cheaper MERV 8 filters for their HVAC systems, they should get MERV 13 to improve their air quality.

“To get a certain MERV value, you have to be able to remove a certain percentage of particles,” Pistochini says. “The higher the MERV rating, the higher the fraction of particles removed.”

However, a HEPA (high-efficiency particulate air) filter, which is the filter of the p read high quality and what you should look for in an air purifier, is the best because it removes at least 99.97% of particles measuring 0.30 microns and above. However, a HEPA filter is not recommended for HVAC systems because its dense nature creates too much resistance to airflow. This is why a MERV 13 filter is used instead, and it removes at least 50% of particles between 0.30 and 1.0 microns in size, with the percentage increasing as the particle size increases.

Note that neither removes gases – for this, many air purifiers come with an activated carbon filter, which is just one step in the filtration process.

Since it’s more efficient to run a portable air purifier than to run an entire HVAC system through ductwork that’s prone to leaks and can contribute to energy losses, Pistochini says it’s best to use air purifiers right in the room, especially in the kitchen, where you cook, and in your bedroom, where you tend to spend long periods of time.

But if you’re wondering whether you should upgrade your HVAC filter to MERV 13 or buy an air purifier with a HEPA filter, Joseph G. Allen, director of Harvard’s Healthy Buildings program and professor at the Harvard TH Chan School of Public Health, tells me you should do both, because they’re not major expenses. Plus, they have important health benefits.

“Air purifiers solve a key problem, which is poor or no general filtration in homes,” says Allen. “Most filters in a home are low quality and are designed to protect equipment. Air purifiers have filters designed to protect people. This is a key distinction.”

The past, present and future of our air, indoors and outdoors

Nationally, a key element in achieving better air quality is the sweeping government regulation known as the Clean Air Act of 1970. A landmark achievement of the environmental movement, this law requires state, local, tribal, and federal agencies to work together to clean our air.

As a result, “air quality in the United States has improved significantly over time, particularly over the past 20 years,” says Hirsch.

According to the EPA’s 2025 Our Nation’s Air report, since 1970, combined emissions of reference or “criteria” pollutants have decreased by 79 percent. Using monitors across the United States, the EPA measures six pollutant criteria: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter and sulfur dioxide.

But even though the Clean Air Act has improved the overall quality of our outdoor air, poor air quality remains an invisible guest in our own homes.

“Hundreds of thousands of lives have been saved [because of the Clean Air Act]”, says Allen. “But this only concerns outdoor air pollution. Our indoor air pollution has continued to get worse. We don’t have an indoor air quality law. »

Inside our homes, we are exposed to volatile organic compounds emitted as gases from everyday items such as cleaning products, upholstered furniture and cosmetics. We are enveloped by particles from cooking and burning candles, as well as biological contaminants such as pollen, mold spores, pet dander, viruses and bacteria. With the flip of a switch, unvented gas stoves and kerosene and gas heaters release carbon monoxide and nitrogen dioxide. Through windows, doors and hidden cracks in our homes, outdoor air pollution seeps inside.

At the same time, our buildings have become more airtight. On the positive side, this prevents energy loss; On the negative side, pollutants remain trapped inside once you close your windows.

Although indoor air quality data is difficult to obtain, our outdoor air quality is something we can easily measure, track, and visualize in our weather apps. And despite the Clean Air Act, we still can’t escape the pollutants in the air we breathe once we leave our homes, especially in specific neighborhoods.

“Just because air quality has improved for a while doesn’t mean the air in your community is better, especially if you have a highway, warehouse or power plant nearby,” Laura Kate Bender, the American Lung Association’s vice president for national advocacy and public policy, told me.

Since 2000, the ALA has published an annual report on the state of the air. In its 2026 report, the ALA found that more than one in four Americans, or 152.3 million people, live in places with unhealthy levels of air pollution. Perhaps even more alarming is that nearly half of America’s children, or 33.5 million people under the age of 18, live in counties with a failing score on at least one measure of air pollution.

A person of color is also twice as likely as a white person to live in a place with a failing grade on all three pollution measures. Hispanics are three times more likely.

Climate change has started to show up in ALA reports, “and it’s reversing some of the progress the country has made in cleaning up these polluting sources,” Bender says.

The majority of experts I spoke with mentioned wildfires, which are intensifying due to climate change. NASA reports that wildfire activity has more than doubled worldwide over the past 21 years. Its satellites detect active forest fires twice a day.

Because of the wildfires, there has been an increase in particulate matter, says Priyanka deSouza, an assistant professor in the department of city and regional planning at the University of Colorado Denver. Research also suggests that levels of ozone, a highly reactive gas both natural and man-made, will increase due to rising temperatures and wildfires.

“It doesn’t look great,” deSouza says.

In February 2022, the United Nations Environment Program reported that extreme fires around the world would increase by up to 14% by 2030, 30% by the end of 2050, and 50% by the end of the century.

A series of proposed and finalized reductions in air pollution limits on gas and coal-fired power plants and on cars by the Trump administration have undermined progress toward clean air. EPA’s Hirsch says the agency is committed to protecting clean air.

Out of breath: the consequences of air pollution on our health

Poor air quality has undeniable immediate effects: breathing difficulties, coughing, irritation of the eyes, nose and throat. Some people may also experience headaches, dizziness, fatigue, and chest pain.

As for long-term exposure to polluted air, it has been linked to lung damage, a higher risk of respiratory infections, chronic diseases like bronchitis and chronic obstructive pulmonary disease, and even cancer. High levels of certain air pollutants can increase the risk of heart attack, stroke, irregular heartbeat and high blood pressure.

Children are more susceptible to the health effects of poor air quality because their lungs are not fully developed, Srikanth (Sri) Nadadur, chief of the exposure, response and technology branch at the National Institute of Environmental Health Sciences, told me. The same goes for older people, due to compromised lung function and the higher likelihood that they will suffer from a lung disease like asthma or COPD.

People with hay fever, heart problems and pulmonary fibrosis (scarring in the lungs) are also more likely to be affected as air quality in the home decreases, according to Dr. Brian W. Christman, national spokesman for the American Lung Association.

Wildfires, in particular, can alter the development of children’s lungs. They are also linked to premature death, heart disease, stroke and lung disease.

Because of their size, ultrafine particles can penetrate deeper into the lungs and release anything they have absorbed along the way, such as VOCs. If these compounds enter the lung fluid, they can enter the circulatory system, potentially affecting cardiovascular function.

“Lately, the literature indicates that it has effects on the brain as well as the reproductive system,” says Nadadur. “There is good evidence from several epidemiological cohorts of an increased incidence of lung cancer due to long-term exposure to outdoor PM2.5, but the association with other cancers is not yet clearly known.”

If you live in an area with poor air quality or have been affected by a wildfire, you should see your doctor if you notice symptoms such as shortness of breath. If you have a lung disease like asthma or other health conditions that a wildfire could make worse, it’s important to plan for these events, especially as they become more common. Make sure you have your medications on hand and know what to do if evacuation is required.

As for poor indoor air quality, remember the three steps to remedying it: Source control, ventilation and air purification.

What your air purifier can (and can’t) do for you

An air purifier uses its fan to draw air indoors, where it passes through various filters to trap airborne pollutants. The freshly filtered air is then expelled to circulate throughout the room.

Each filter is designed to capture different sizes and types of pollutants. Chloe Waller, sales director at Airthings, explains that a well-designed air purifying filter system works in three stages.

Step 1: The pre-filter

Usually made of fabric and designed to extend the life of other filters in the system, this exterior filter is coarse to capture larger particles, such as pet hair, lint and visible dust. Some units make this filter washable or vacuumable.

Step 2: The f HEPA ilter

HEPA filters can capture microplastics and some nanoplastics, dust, pollen, mold spores, some bacteria and viruses as well as PM2.5 particles, which can come from smoke from wildfires, cooking, using a fireplace, vehicle exhaust and industrial pollution.

CNET’s 2025 lab tests in a smoke chamber confirmed that air purifiers with a true HEPA filter can capture viruses that could cause diseaseincluding influenza and SARS-CoV-2, which causes COVID-19.

In 12 models tested, CNET Labs found that with a low fan setting, the Shark HP232 The air purifier performed best in removing fine particles 2.5 microns and smaller, averaging 1 minute and 15 seconds. At high fan speed, the Coway Airmega 400S was best at removing fine particles in 34 seconds on average.

Step 3: The activated carbon or carbon filter

While HEPA captures particles, an activated carbon filter targets gases such as VOCs and odors from smoke, pets, and cooking. Peter Mann, CEO of Oransi, creator of CNET’s ‘Best for Pet Hair and Dust’ Air Purifieradded that activated carbon filters can also absorb gases such as ammonia, formaldehyde and hydrogen sulfide.

Although activated carbon filters can remove ozone, the effectiveness of this process depends on the amount of activated carbon in the filter. However, there is no system for evaluating the performance of filters designed to remove gases.

But there is a rating system for particles: clean air flow. The higher the CADR, the larger the area an air purifier can filter.

“My general rule of thumb is you want to have 300 CADR for every 500 square feet,” says Allen. “Depending on the exact size of your room, we try to target four, five or six air changes per hour.”

Although many air purifier manufacturers list the room size on their packaging, they may not display the CADR. This means that the air purifier might not be effective unless you use it in a smaller room than indicated on the product packaging.

After all, your air purifier can’t filter what it can’t capture, which is why you need to make sure it’s properly sized for your space. Harvard’s Healthy Buildings Program has a sizing tool for this purpose.

“Most consumer purifiers are rated for rooms up to 500 to 600 square feet,” says Waller. “In large open spaces, or where doors and windows are regularly opened during a smoke event, a single unit operating in automatic mode may not maintain clean air throughout the space.”

You’ll also want to make sure your air purifier has a true HEPA filter, not one labeled HEPA-type or HEPA-type.

Changing the HEPA and activated carbon filters is crucial. Collected pollutants build up and clog filters, and dirty filters can actually release them back into your home, making the air quality even worse than it was before you installed your air purifier.

What an air purifier can’t capture

Air purifiers capture airborne particles and some gases as air passes through the machine, meaning whatever they remove must first be suspended in the air and drawn into the purifier.

There are a few things they can’t fully address: “Hazardous gases like carbon monoxide and radon require dedicated detectors and professional remediation,” says Nedra Ogden, senior product manager at Blueair, maker of CNET’s Most Recommended Air Purifier.

Radon is an invisible, naturally occurring radioactive gas that enters homes through cracks and gaps in the ground as radioactive metals break down in soil, rocks and groundwater. Carbon monoxide is also an invisible gas, and its sources include gas stoves, leaking fireplaces, and unvented kerosene and gas heaters.

Air purifiers also can’t capture the carbon dioxide we exhale.

“When you don’t have proper ventilation and lots of people are breathing, carbon dioxide levels can increase, which can lead to migraines and headaches,” says deSouza.

Although activated carbon filters can absorb VOCs, there is a limit, especially if they become saturated and are not replaced regularly.

Air purifiers also can’t handle temperature and humidity. Although they can capture moisture-loving mold spores floating in the air, Petra Oman, vice president of marketing at air and home care technology company SharkNinja, tells me that these products can’t eliminate mold growing on surfaces or solve a widespread mold problem in your home. For the latter, the EPA recommends a professional mold remediation service.

To determine if your air purifier is effective, experts recommend investing in one air quality monitor. THE the one I have in my living room measures radon, PM2.5 particles, CO2, VOCs, atmospheric pressure, humidity and temperature.

Some air purifiers have a built-in air quality monitor, so the purifier automatically adjusts its speed based on the level of certain pollutants. However, air purifiers may not display pollutant numbers like a dedicated monitor, and will only show pollutants around the machine – not the entire room.

“It’s a classic business maxim: What gets measured gets managed,” says Allen. “If we don’t know what the levels are, we don’t really know what we’re trying to manage.”

Are special features just hot air?

Beyond a true HEPA filter, you don’t need fancy air purifier features.

Air purifiers that tout UV light filters or ozone and ion-producing technologies may do more harm than good because they produce ozone, a pollutant that can worsen airway inflammation and exacerbate asthma and hay fever.

For this reason, in 2008, the California Air Resources Board adopted air purifier regulations aimed at limiting ozone emissions from indoor air purifiers, requiring the board to certify all indoor air purifiers sold in the state.

“There’s a lot of marketing around air purifiers,” says Mann. “I think part of this is because consumers can’t see what an air purifier removes from the air.”

The pure potential of future air purifiers

Eventually, air purifiers could have more built-in sensors that adjust speed in real time to capture more pollutants, so a separate air quality monitor would not be necessary.

We may at some point see air purifiers connected to HVAC systems and other smart home and health devices, so that all technologies – cooling, heating, humidification, air quality, health – can work holistically to create a healthy environment. This would help link indoor air quality to sleep, productivity, illness and other vital health factors.

Air purifiers could even be integrated into walls, furniture and lighting rather than being standalone devices, according to Gil Jung, director of Coway USA, manufacturer, to CNET. favorite air purifier for the whole house.

“AI-based predictive purification is also a possibility, so rather than reacting to pollution, systems will anticipate it,” says Waller. “Imagine a purifier that precharges into boost mode when it senses from external data sources (air quality forecasts, local wildfire tracking) that conditions are about to deteriorate.”

Your air purifier would turn on before you even smell smoke.

Stuart Thompson, senior design director for environmental protection at Dyson, tells me we’ll see innovations in filtration systems, going beyond HEPA and activated carbon, with “multiple specialized layers to target an even wider range of pollutants.” They will be able to capture ultrafine particles, absorb more complex gases and break down certain pollutants at the molecular level.

Although true HEPA filters are currently not reusable, according to Hirsch, research indicates that reusable filtration systems are a future product development.

Once air passes through these filters, motion sensors could direct the purified air to people based on where they are in the room. Thompson expects future air purifiers will throw air further and circulate it more efficiently through larger spaces, so that every corner of the room will receive clean air.

It would be great to see air purifiers produce less noise, which could encourage more people to use them.

According to CNET Labs 2025 tests, at low fan speeds, the quietest air purifier was the BlueAir 311i at 34.84 dBA. At high fan speeds, the quietest model that still effectively filtered particles measuring 0.30 microns was the 51.56 dBA Shark HP102. This compares to about 60 dBA for people speaking 3 feet away.

But while we wait for the air purifiers of the future, there is still much to be done to prevent future generations from having to worry about air pollution.

Air awareness and action

Although air purifiers can improve indoor air quality, we can’t expect much from a device when it comes to combating air pollution as a whole.

“Until we stop burning fossil fuels and other harmful fuels for our energy, transportation and production, we are essentially trying to make the health impacts as less serious as possible, but we are not “We’re not really stopping,” says Bender.

Education and awareness are essential. Just like you monitor the weather, you need to monitor your air quality, both indoors and outdoors. Not only to know when to stay indoors, avoid outdoor ventilation, or turn on your air purifier, but also to see the problem firsthand, as I did during the Eaton fire.

The problem of air pollution is more than a single household can solve, which means collective action is needed. This will require reaching out to policymakers, whether it’s your school board, city council, state officials, federal agencies, or the White House, to share your stories and thoughts on air pollution and climate change in an effort to promote change.

Just like you wouldn’t drink a glass of dirty water or eat food visibly covered in microplastics, you shouldn’t have to breathe polluted air. After all, breathing is not an option. Breathing clean air shouldn’t be either.

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