The strong winds pound against the windowpanes with an intensity I have never experienced. The sky appears a strange gray - not due to clouds, but from smoke. A large wildfire burns close by. Danger feels near.

In our apartment on the second floor, my partner and I gather our key items and a few valued belongings. We seal the window edges with tape to block smoke and ash from entering and watch a map showing the fire's movement.

The growing tension and worsening air conditions become overwhelming. We drive 20 miles south to a hotel and remain there until the fire is better contained. Even at that location, ash falls from above.

I reside in Pasadena, and our home sat just beyond the evacuation area for the Eaton Fire, which claimed 19 lives and damaged more than 9,400 buildings in January 2025. That month, the Eaton and Palisades fires burned at the same time in Southern California and ranked as the second- and third-most damaging wildfires in the state's history.

We were fortunate because the fire halted five miles from our building. Although many people lost their homes, we returned to ours. Still, the sealed windows failed to stop ash and smoke from entering through gaps and settling on surfaces throughout our space.

With poor outdoor air quality, we avoided opening windows, so we depended on our air purifier. At that point, we owned only one unit in the living room. Since then, we have added a second unit in the bedroom along with air quality monitors in both rooms.

The air risks continue: As I write, smoke from a warehouse fire in Boyle Heights drifts our way, making it unwise to open windows once more.

Fires add greatly to bad air quality, but they are not the sole cause. Power plants that burn fossil fuels release pollutants, as does vehicle exhaust from roads and highways. This explains why weather apps on phones show the daily air quality index, or AQI. Although outdoor air quality across the US has improved over the years, gains have not occurred everywhere, especially in communities of color.

Do air purifiers provide the fresh air we seek?
The initial two steps to improve air quality
HVAC systems versus air purifiers: Which helps more?
The history, current state and outlook for our air, both inside and outside
The health impact of air pollution
What an air purifier can and cannot achieve
Items an air purifier cannot remove
Are added features worthwhile?
The future promise of air purifiers
Building awareness and taking action

Indoor air also carries risks from gas appliances, furnaces, household chemicals and emissions from furniture and products. Outdoor pollution finds its way inside as well.

After 12 years as a health and wellness writer, I have noticed that worries about the air we breathe 12 to 20 times each minute often receive less attention than needs such as clean water and safe food. Yet basic actions can enhance air quality at home.

Air purifiers can reduce certain contaminants, as tests have shown, but they are not the top or only defense against poor air.

Do air purifiers provide the fresh air we seek?

Air purifiers resemble speakers - rectangular or round devices under three feet tall with vented metal or plastic exteriors. They usually sit on the floor or a table in busy spots such as the bedroom, living room or kitchen. Costs range from 50 to 1,000 dollars.

I did not have air purifiers growing up, but my mother now owns two in her suburban New York home. She once used only her HVAC filter, yet when COVID-19 cases rose during the pandemic, she bought air purifiers.

Representatives from air care firms such as Dyson, Blueair, Airthings, Coway and Oransi report increased sales during events that raise health concerns about air, including the COVID-19 pandemic, wildfires, urban smog and allergy season.

My colleague Tara Brown, CNET social media manager, recently purchased her first air purifier. It was not something she knew from childhood, and it initially felt like an extra expense.

"My mother handled dust by opening windows during cleaning, and in pollen season we kept windows shut while taking daily allergy medication," Brown, who lives in an East Coast suburb, says. "Now that I am older and manage my own budget, I want to try one because I react to dust and pollen."

Brown's mother was correct to open windows. As I have learned, that ranks as the second step when addressing poor air quality, even before using an air purifier.

The initial two steps to improve air quality

The first action is to limit the pollution source.

"In cities, vehicles once produced the most volatile organic compounds, but cars have improved, and now the main source appears to be products used in homes," Linsey Marr, a distinguished professor in Virginia Tech's Department of Civil and Environmental Engineering, explains.

This covers everyday items such as shampoo, lotion, hairspray, deodorant, cleaners and paints.

For low- or no-cost ways to manage VOCs, Brigit Hirsch, press secretary for the US Environmental Protection Agency, advises following product directions closely to avoid overuse and to check needed ventilation. When painting, for example, keep windows open.

For gas and particle pollution from stovetop or oven cooking, activate the range hood to vent it outside. If the hood vents outdoors, skip it on days with high outdoor pollution. An air purifier near the stove can capture cooking particles and, with an activated carbon filter, some gases.

To clear particles from surfaces before they become airborne, vacuum often with a filtered vacuum and dust with a damp cloth. Dampen the cloth with mild cleaners such as soap and water that lack ammonia or chlorine, which can harm air quality.

"The key step for air pollution is source control, so reduce the sources causing the pollution first," Glory Dolphin Hammes, CEO of IQAir North America, states. IQAir operates the world's largest free real-time air quality monitoring platform and sells air purifiers.

After addressing sources, ventilate. Open windows, run kitchen or bathroom fans that vent outside and use window or attic fans to stop pollutants from accumulating indoors.

When ventilation is not possible due to high outdoor pollution, such as during a wildfire or rush hour near a busy road, turn to air purification.

HVAC systems versus air purifiers: Which helps more?

Many are surprised to learn that HVAC filters were first made to protect system coils, not human health.

Theresa Pistochini, co-director of engineering at the UC Davis Energy Efficiency Institute and Western Cooling Efficiency Center, notes that home HVAC systems often run only when heating or cooling to save energy, so the fan does not operate continuously. This means the system does not filter air constantly, and even when running, the filter may not be the best grade.

Pay attention to MERV, or minimum efficiency reporting value, based on a test from the American Society of Heating, Refrigerating and Air Conditioning Engineers. While many choose lower-cost MERV 8 filters, MERV 13 filters improve air quality.

"A certain MERV value requires removing a set percentage of particles," Pistochini says. "Higher MERV ratings remove a greater share of particles."

A HEPA filter, the top grade found in air purifiers, removes at least 99.97 percent of particles 0.30 microns and larger. HEPA filters are not suited for HVAC systems because they restrict airflow too much. A MERV 13 filter removes at least 50 percent of particles from 0.30 to 1.0 microns, with higher removal for larger sizes.

Neither type removes gases. Many air purifiers include an activated carbon filter for that purpose as one stage of cleaning.

Running a portable air purifier uses less energy than an entire HVAC system with leaky ducts, Pistochini says, so place purifiers in the room - especially the kitchen and bedroom where people spend more time.

If choosing between upgrading an HVAC filter to MERV 13 or buying an air purifier with a HEPA filter, Joseph G. Allen, director of Harvard's Healthy Buildings Program and a professor at the Harvard T.H. Chan School of Public Health, recommends both, as costs are modest and health gains are clear.

"Air purifiers address a main issue: low or absent filtration in homes," Allen says. "Most home filters are basic and protect equipment. Air purifiers use filters designed to protect people. That difference matters."

The history, current state and outlook for our air, both inside and outside

Nationally, the Clean Air Act of 1970 stands as a major rule for better air quality. This law, a key win for the environmental movement, requires state, local, tribal and federal groups to work together to clean the air.

As a result, "air quality in the US has improved greatly over time, especially in the last 20 years," Hirsch says.

The EPA's 2025 Our Nation's Air report states that since 1970, combined emissions of key pollutants have dropped 79 percent. The EPA tracks six criteria pollutants across the US: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter and sulfur dioxide.

In this article:

Do air purifiers provide the fresh air we seek?

The initial two steps to improve air quality

HVAC systems versus air purifiers: Which helps more?

The history, current state and outlook for our air, both inside and outside