Asthma

What asthma is

Asthma is a chronic disease of the airways, the tubes that carry air in and out of the lungs. In a person with asthma, those airways are inflamed and overly sensitive, so they react to triggers that healthy lungs would ignore.

When a trigger hits, three things happen at once. The airways swell, the muscles around them tighten, and they produce extra mucus, the American Lung Association reports. Together those changes narrow the passages and make breathing hard, producing the wheezing, coughing, chest tightness, and shortness of breath of an asthma attack. There is no cure. The disease is managed by controlling inflammation with medication and, just as importantly, by reducing the exposures that set attacks off. That second part is where the home comes in, because a person can take every prescribed medication and still struggle if the air around them keeps triggering the disease.

How environmental triggers drive asthma

Asthma attacks do not come from nowhere. They are set off by triggers, and many of the most common ones live inside the home. The EPA identifies indoor allergens and irritants as major asthma triggers, and it lists several that turn up in ordinary houses.

Dust mites top the list. These microscopic creatures live in bedding, carpet, and upholstery, and their waste is one of the most common indoor asthma triggers in the country. Mold is next. It grows wherever moisture collects, and the EPA reports that damp, moldy homes raise the risk of asthma symptoms. Pet dander, the tiny flakes of skin animals shed, triggers attacks in people sensitized to it. Cockroach droppings and body parts are a major trigger, especially in older and urban housing. Secondhand smoke inflames airways directly, and the CDC reports that it triggers attacks and worsens asthma in children who breathe it. Add the fumes from cleaning products, the nitrogen dioxide from a gas stove, and the fine particles from cooking and candles, and the home becomes a collection of triggers stacked in the one place a person spends most of their time.

How indoor and outdoor exposures connect

The triggers inside a home do not stay separate from the pollution outside it. Outdoor air drifts in through windows, doors, and the gaps in every building, so the air quality on a street sets the baseline for the air in a living room.

Three outdoor exposures reach indoors and hit people with asthma hardest. Ground-level ozone, which forms when sunlight cooks pollution from traffic and industry, inflames the airways and is a well-documented asthma trigger, the EPA reports. Fine particulate matter, or PM2.5, travels deep into the lungs and can set off attacks within hours. Pollen drifts inside during allergy season and lingers in carpet and bedding long after the outdoor count drops. Wildfire smoke ties them together, since it carries huge loads of PM2.5 across entire regions and forces an impossible choice for a person with asthma: open the windows for relief from indoor heat, or keep them shut to block the smoke. The indoor and outdoor sources combine into a single load on the airways, and for someone with asthma, the combination is what matters.

Who is most at risk

Asthma does not fall evenly across the country. Three groups carry a far heavier burden, and the gaps trace back to where and how people live.

Children come first. Asthma is one of the most common chronic diseases in American children, affecting about 4.5 million of them, the CDC reports, and it is a leading cause of missed school days. Children breathe faster than adults and take in more air relative to their body size, so they absorb more of whatever a home holds, and their airways are still developing.

Race and income widen the gap sharply. Black Americans are far more likely to have asthma than white Americans, and the CDC reports that Black children are about twice as likely to have asthma as white children and several times more likely to die from it. Puerto Rican Americans have among the highest asthma rates of any group in the country. The reasons are environmental, not genetic. Low-income families and families of color are more likely to live in older housing with mold, pest infestations, and deteriorating conditions, and more likely to live near highways, industrial sites, and other sources of pollution. A 2021 study in the journal Science Advances found that Americans of color are exposed to higher levels of fine particulate pollution than white Americans across nearly every source of it. The families with the most asthma are often the ones with the least power to change the air around them.

The scale of asthma in the United States is large and steady. About 25 million Americans have the disease, the CDC reports, a number that has held near the top of its range for years after climbing through the late 20th century. Roughly 1 in 12 people and 1 in 12 children live with it.

The cost is measured in more than diagnoses. Asthma causes about 1 million emergency room visits a year and more than 3,500 deaths, the CDC reports, and it drives millions of missed school and work days. The American Lung Association estimates asthma costs the US economy more than $80 billion a year in medical bills, lost productivity, and early deaths. The disease also concentrates geographically, clustering in places with older housing stock and higher pollution, which is why asthma rates can vary sharply from one neighborhood to the next within the same city.

What a household can do

Control moisture first, because damp is what feeds mold and dust mites, two of the most common indoor triggers. Keep indoor humidity between 30 and 50%, fix leaks fast, run bathroom and kitchen exhaust fans, and dry any wet material within 24 to 48 hours. A dehumidifier helps in a basement or any space that stays damp.

Attack the specific triggers next. Wash bedding weekly in hot water and use allergen-proof covers on mattresses and pillows to cut dust mites. Vacuum with a HEPA filter and dust with a damp cloth to capture allergens rather than scatter them. Keep the home smoke-free, since the CDC reports secondhand smoke is a major trigger for children, and never let anyone smoke inside or in a car. Seal cracks and store food in sealed containers to keep cockroaches out, and use bait rather than sprays, which add irritating fumes. If pets trigger attacks, keep them out of bedrooms at a minimum.

Clean the air the household breathes all day. Run the kitchen exhaust fan every time you cook, especially on a gas stove, which releases nitrogen dioxide. Check the Air Quality Index at AirNow.gov before outdoor activity, and on high ozone, high particulate, or wildfire smoke days, keep windows closed and run a portable air cleaner with a HEPA filter sized for the room. Choose fragrance-free, low-VOC cleaning products, since strong fumes trigger attacks. And work with a doctor on an asthma action plan, because reducing triggers and using prescribed medication together control the disease far better than either alone. If you rent, know that most states require landlords to fix serious hazards like mold, pest infestations, and broken ventilation, and local health departments can enforce those rules.