How to improve indoor air quality

Indoor air pollutants to look out for and how to tell if your indoor air quality is bad.

Amanda Capritto
8 min read
close-up of a dirty AC filter

How dirty is the air in your home?

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Ever since the spate of wildfires broke out across the West Coast this year, a certain statement has been circulating social media: Your indoor air quality is worse than the outdoor air quality. I wanted to find out if there was any truth to this, so I asked a few indoor air quality experts. 

According to the Environmental Protection Agency (EPA), indoor air quality can be two to five times worse than outdoor air quality. David Bloom, chief science officer of Green Home Solutions, says that it's not unusual to see indoor air quality levels even worse than that. 

Yikes, right? 

But, this social media frenzy about indoor air quality began as fires raged across several states, leaving a haze around millions of residences. Is it possible that one's indoor air quality could be worse than the outdoors, even in the event of a wildfire? 

"A wildfire is taking outdoor pollution to an extreme," Bloom says. "However, there are many pollutants generated indoors totally unrelated to what is happening outside. Part of the issue is that, as we build tighter and tighter homes, the building loses its ability to breathe unless there is sufficient mechanical ventilation." 

So, although it's unlikely that your living room is less safe than a wildfire-ridden forest, indoor air on a regular basis can be quite polluted. Knowing how to monitor your indoor air quality and what specific pollutants to look out for can save you a lot of acute (read: achoo!) symptoms and long-term health consequences.

Indoor air pollutants to watch for

a woman vacuuming up dust from beneath a bed

Dust is always lurking, whether you know it or not.

PeopleImages/Getty Images

Turns out, there are more than a handful of pollutants that could be in your home at any given moment. 

Dust: A common indoor air pollutant, dust gets tracked in from outside, but can also accumulate from indoor sources, including pet dander, dead skin, food debris and more. 

Lint: You probably take care to remove the dryer lint from the lint trap after each load of clothes. However, lint can get trapped in places you can't see, like the dryer vents behind your clothes dryer, says Jason Kapica, president of Dryer Vent Wizard. "Lint mixed with water from a clogged dryer vent can create a pasty mess," he continues. "A clogged dryer vent will spew this concoction from the back of your dryer, causing it to harden in the vent and stick to the wall behind the dryer." This can create a dangerous situation for families with gas dryers , which can push carbon monoxide into homes when this happens.

Mold and mildew: When moisture and warm temperatures combine, "the result is mildew and mold spores," Kapica says. "These microscopic spores compromise air quality causing respiratory issues and driving asthma attacks."

Animal droppings: No, not like your new puppy's accident on the carpet. Small animals and pests look for cozy spaces to sleep and breed -- and this often means nooks and crannies within your home. These animals lay eggs and leave droppings, and inhaling dust laced with rodent and bird droppings can contribute to health problems, Kapica says.

Environmental tobacco smoke or secondhand smoke: As someone who's lived next door to a cigarette smoker, I know unwelcome secondhand smoke can make its way into your home. Environmental smoke, such as from wildfires, can leak in through doors and windows that aren't airtight, as well as any time you open a door or window.


Fires, like the ones currently happening in the US West, can send particles inside your home.

Getty/Josh Edelson

Pollen: Pollen from trees, grass and other plants outdoors can easily make its way inside, especially if you leave windows open regularly. 

Pesticides: Lawn and garden pesticides can make their way into your home, even if you don't necessarily use them on your own property, Bloom says. 

Vehicle exhaust: This is a common one for apartment dwellers in big cities, Bloom says, especially where the apartments are situated above a garage. 

Pet dander: Pets are a known household pollutant, but this definitely doesn't stop people from adopting fur babies. Keeping your pets brushed and clean can help reduce pet dander. 

Volatile organic compounds: This class of chemicals is the most common indoor air quality issue, said all of the experts tapped for this story. VOCs are emitted as gases from liquids and solids, including common items such as paints, hair spray, furniture, cookware, cleaning supplies, glue, markers, printers and ink and more. 

Radon: "A known human carcinogen, radon is a very common pollutant that occurs naturally in the ground [and] can make its way indoors," Bloom says. 

Asbestos: Newer homes don't (or shouldn't) have asbestos, but many older homes still do. This group of carcinogenic minerals is known to cause cancer, mesothelioma and other fatal health conditions.

Your own skin: Ick. Dead skin cells fall all over your home every day and attract dust mites, says Marla Mock, vice president of operations for Aire Serv. "Skin cells are a primary food source for dust mites, which then become another source of indoor air pollution. Dust mite allergies range from mild to severe depending on the individual. We further contribute to the problem as we exhale carbon dioxide, as so few homes are properly ventilated for dilution."

How to monitor your indoor air quality


There are several indoor air quality monitors on the market, like this one from Kaiterra.


Now you know what to look out for, but how do you actually watch for those things? Things like dust and pet hair can be obvious in certain parts of the home, but other pollutants are invisible to the human eye -- or just hidden in ducts, vents, walls and other nooks and crannies.

One easy thing you can do is know the physical signs of poor air quality in humans and pets. If you have poor indoor air quality, you might suffer from allergylike symptoms, such as a runny or stuffy nose, watery eyes, sneezing and a scratchy throat. You might also experience mild headaches. If your indoor air quality is particularly bad, you could develop more severe symptoms, such as chest tightness or shortness of breath, fatigue, dizziness or nausea. 

If you already have allergies, monitor your symptoms to determine whether they're worse than usual, or if you develop any new or unusual symptoms. People with seasonal allergies can experience allergy-like symptoms even during their "off-season." Symptoms that are actually due to poor indoor air quality should subside when you leave your home (unless the outdoor air quality is worse), so that's one way to tell if your home truly needs some air purification. 

The hows and whys of monitoring air quality in the home

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In pets, similar symptoms can manifest. Monitor your pet for coughing, sneezing, gagging, watery eyes, excessive scratching, open-mouth breathing (even in cool environments) disorientation and decreased appetite or thirst (PDF). 

If monitoring your symptoms is too tough, you can buy a device that'll monitor your indoor air for you. Indoor air quality monitors work by tracking temperature, humidity and levels of particulate pollutants. For example, some air quality monitors check for radon, while others check for carbon dioxide, dust or formaldehyde. 

Most indoor air quality monitors can't check for every single indoor air pollutant, so if you choose to buy one, it's up to you to decide which pollutants are most important to you. Those who live on the West Coast, for instance, may find it most beneficial to buy an indoor air quality monitor that tracks environmental smoke in the home.

How to improve your indoor air quality


Air Purifiers, like the Dyson Pure Cool, can help improve your indoor air quality.

Ry Crist/CNET

Nearly all indoor air pollution, depending on the intensity, can be controlled with "proper ventilation, filtration and in some cases, additional air treatment devices to eliminate bacteria, viruses and other unwanted material," Mock says.

Invest in an air purifier: An air purifier is often the first defense against stuffy indoor air. A high-quality one can significantly reduce allergens and pollutants in your home and help circulate clean air.

Introduce fresh air: If the outside air in your area isn't affected by wildfires, dust storms or other natural disasters, letting fresh air in can help. "This may sound silly, but often 'the solution to pollution is dilution,'" Bloom says. 

Get your ducts and vents cleaned: If you have a lot of buildup in your air vents and ducts, you may need to bring in a professional to clear things out first. 

Clean AC ducts regularly: Keeping your AC ducts clean is probably one of the best things you can do to improve your indoor air quality, Bloom says, as is using a high-quality AC filter. 

Clean dryer vents regularly: Leading appliance manufacturers recommend dryer vents be thoroughly cleaned once a year to prevent hazards to your health, Kapica says. Dryer vent cleaning removes lint, dust, hair and other debris to ensure proper and clean air flow, he says.

Consider additional AC filtration: Dr. Neeta Ogden, an allergy, asthma and immunology specialist, encourages people to use high-quality air filters for air conditioning units and even box fans. Placing a HEPA filter on the backside of a box fan can act as a DIY air purifier.

Avoid burning candles and wood inside: As much as you love your candles (guilty here), reducing or eliminating your use of them can significantly improve your air quality, says Bloom.

a purple candle burning on a silver background

Candles smell nice, but they can contribute to poor indoor air quality.

Image Source/Getty Images

Make sure your doors and windows are airtight: Leaky doors and windows allow outdoor pollutants such as smoke, dust and pollen to enter and build up inside your house.

Stay indoors during fires: This might sound obvious, but avoid as many trips outside your house as possible if there is a wildfire near you. Every time you open the door, you not only risk pollution irritation outside, but you also risk allowing smoke inside your home. 

Use no- or low-VOC personal care products: Many VOCs come from personal care products such as hair spray, Bloom says. Look for personal care products with reduced VOCs or none at all to reduce indoor air pollution.

Buy no- or low-VOC furniture and household goods: Deborah DiMare, a non-toxic focused interior designer who works with the National Asthma Foundation, recommends avoiding sheets, furniture and other household items that might be ridden with formaldehyde and other VOCs. 

"Ditch 'wrinkle-free' sheets, which may cause respiratory issues, and replace them with organic cotton or bamboo bedding," she says. "Swap out pillows with synthetic stuffing or memory foam that may off-gas benzene, and replace them with non-toxic options such as kapok, organic cotton or 100% natural latex stuffing." Checking for the Global Organic Textile Standard (GOTS) badge can ensure you avoid VOCs in household goods.

Invest in pest control: Keeping pests out of your home can prevent air quality problems by reducing eggs, droppings, dust and animal hair. 

Check for and fix water leaks: Water leaks are a leading cause of mold, which is a leading indoor air pollutant. 

Carefully store gas-powered equipment and lawn care items: We all love a trimmed yard and nice landscaping, but achieving those things usually requires equipment like a lawn mower and weed-eater, as well as pesticides. Bloom recommends keeping these items away from the perimeter of your home -- don't even put them in your garage, he says, as fumes can easily track inside from there. 

Finally, stay knowledgeable on your local air quality: Smoke levels can change throughout the day, so monitor the air in your area, Dr. Ogden says.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.