Air isn’t as light as it seems. It’s pushing on your skin right now with up to 15 pounds of pressure per square inch, a weight so familiar you can’t feel it. Your lungs feel it, though, especially when it’s bogged down with toxins. And while we tend to think of air pollution as an outdoor threat, it can be even worse inside the buildings where we live and work.
The causes of indoor air pollution vary from region to region, house to house and even room to room. Contaminated air seeps in from outside, but it also wafts up from a smorgasbord of indoor sources like construction materials, consumer products, mold, insects and pets. Poor ventilation can let it accumulate to dangerous levels, a problem that often spikes in fall and winter as we seal up buildings to conserve heat.
If you’re concerned about the air inside your home or office — two places where many people do the bulk of their breathing — you might want to pick it apart with indoor air-quality testing. To help you clear the air once and for all, here’s a look at some of the most common indoor air pollutants, how to detect them and how to deal with them.
Gases and particles from combustion are the leading sources of indoor air pollution worldwide. Household cookstoves alone kill about 4 million people every year, mostly in developing countries, but this category also includes heating stoves, fireplaces, furnaces, space heaters and tobacco smoke. The top pollutants released by combustion are carbon monoxide (CO), nitrogen dioxide (NO2) and particulate matter.
CO causes an array of symptoms — from headaches and nausea to confusion and unconsciousness — and kills about 500 people in the U.S. per year. NO2 irritates mucous membranes and causes shortness of breath, and long-term exposure to low levels may raise the risk of lung infections or emphysema. Airborne particulates can lodge in the lungs, potentially damaging tissue and even working their way into the bloodstream.
Another colorless and odorless gas, radon, is the No. 2 cause of lung cancer in the U.S., killing about 21,000 Americans every year. Nearly all soil contains low levels of decaying uranium, which emits radon, although certain regions have more than others. It normally dissipates harmlessly into outdoor air, but it can also flow into buildings through gaps in the foundation, eventually reaching unsafe levels in basements and lower floors.
While the EPA’s radon zone map can hint at your general risk, air-quality testing is the only way to be sure. DIY radon test kits are available online and in home improvement stores, but the EPA suggests contacting your state radon office first, as some states offer free or discounted kits. And since careful steps must be taken to ensure an accurate reading, many people opt for a qualified radon inspector, especially when buying a home.
The average indoor radon level is 1.3 pico curies per liter (pCi/L), and the EPA recommends taking action if you detect a level of 4 pCi/L or higher. Radon remediation involves sealing off the building’s interior from exposed soil, a complex task typically best left to professionals.
Like radon, asbestos occurs naturally in soil, posing little health risk until it gets indoors. While radon sneaks in, however, most asbestos is an invited guest that has overstayed its welcome. The heat-resistant mineral fiber has long been used as a building material and insulator, but its stock crashed in recent decades amid news that inhaling its fibers can cause lung cancer, mesothelioma and long-term lung scarring.
Most modern homes and offices now use alternative materials, but older buildings may still contain asbestos. Even then, the fibers only become airborne when they’re disturbed, so the most practical solution is often to simply leave asbestos alone.
Given the risks involved, DIY asbestos remediation is rarely a good idea. Even taking your own samples for testing isn’t recommended. If you suspect a material contains asbestos, look for signs of damage without touching it, then contact a professional inspector to learn more. Federal law doesn’t require accreditation for asbestos work in single-family homes, but some states and municipalities do. See this list of state asbestos contacts for help.
4. Mold and mildew
Fungi are notorious indoor air polluters, seizing on warm, humid conditions to colonize and contaminate. Outbreaks often begin in basements and bathrooms, but can quickly spread with enough moisture. Health effects vary by mold type and personal sensitivity; symptoms may include nasal stuffiness, wheezing and skin irritation. Studies have also linked indoor mold exposure to asthma development in children.
The best way to fight mold is to fight moisture. Keep the relative humidity indoors below 60 percent, and use a dehumidifier or fan to dry out the air if needed. Pockets of mold can be removed from hard surfaces by scrubbing with soap and water, a bleach solution or hydrogen peroxide, but check EPA guidelines for larger-scale cleanups.
5. Dust, dander and droppings
Mold isn’t the only biological polluter of indoor air. Many buildings are plagued by dust mites and cockroaches, two very different arthropods that both leave a trail of allergenic feces and body parts. Fumes from rodent urine and droppings can also cause breathing problems, as can pet dander and airborne proteins from cat saliva. On top of that, indoor air may be invaded by pollen and bacteria from outside.
These contaminants often trigger allergic reactions and asthma, and symptoms can grow worse with chronic exposure. Children, elderly people and people with other breathing issues are especially at risk from biological agents in confined areas, the EPA warns.
Testing can sniff out some biological pollutants, but as with mold, it may be easier to use visual clues. Regular sightings of roaches, rats or their droppings point to an infestation, in which case pest control is likely the best way to clear the air. Dust mites aren’t visible to the naked eye, but we can see piles of their namesake food — and cleaning up dust may also alleviate allergies from pet dander. Beyond good housekeeping, ventilation can help keep unavoidable allergens from reaching high concentrations.
Even though rodents, insects and other pests are a common source of indoor air pollution, eradicating them with poisons can raise the risk of trading one problem for another. Pesticides are inherently toxic, the EPA notes, often featuring organic compounds that add to existing levels of airborne VOCs. Health effects vary depending on the chemical and dosage, but symptoms of pesticide exposure range from headaches and nausea to long-term brain damage and increased risk of cancer.
Three-quarters of U.S. households have used at least one pesticide indoors during the past year, according to the EPA, mostly insecticides and disinfectants. These indoor chemicals account for up to 80 percent of most people’s total exposure to pesticides.