10 Mistakes You're Making That Could Hurt Your Home's Air Quality

When you think of pollution, outdoor air probably comes to mind, but the quality of the air inside your home matters, too. Dust mites, gases like carbon monoxide, mold, pollen, volatile organic compounds (VOCs), and other pollutants can float unseen through the air, triggering allergies or serious health concerns. And though they might seem harmless, certain everyday activities, such as cooking, cleaning, or taking a shower, can make your indoor air quality worse. Fortunately, a few simple tweaks can help you and your family breathe a bit easier. Avoid these common mistakes to help ensure the air in your home is as clean as it can be.

1. You're bringing pollutants into your home.

Taking off shoes at the front door can reduce the allergens and germs tracked in. "Pollens are microscopic particles that get stuck in your eyes, nose, and hair, and on your clothing," says Amy Shah, M.D., a board-certified allergist and immunologist and internal medicine physician in Phoenix. A pair of doormats—one outside and another right inside—will limit the number of outdoor allergens that make it beyond the threshold. For the outdoor mat, coir (made from coconut husks) is a good pick because it's water-resistant, so it won't get musty, says professional organizer and certified house cleaning technician Donna Smallin Kuper. The indoor mat should be easy to pick up and shake outside, though it's still smart to vacuum this area often; every day is not overkill when allergies are at full force. Keep a stiff boot brush on your doorstep to help get extra gunk off muddy boots and sneakers.

2. You're not keeping humidity in check.

If a room feels damp or smells musty, that's a red flag that mold could be growing and dust mites are proliferating. To measure humidity, buy an inexpensive hygrometer ($11, The Home Depot) at your local hardware store or online and make sure the humidity stays below 60%, says David Corry, M.D., professor of medicine in the section of immunology, allergy, and rheumatology at Baylor College of Medicine in Houston. If it's above that, consider adding a dehumidifier.

"Being warm and wet makes the bathroom the main place that dust mites and mold grow," Shah says. Wash towels at least once a week and crack a window or turn on an exhaust fan every time you shower. Exhaust fans are designed to pull moisture out of the air and can get dirty, so consider having a professional come in to clean and maintain the system annually.

3. You don't regularly replace your HVAC system's filter.

Your heating and air-conditioning system continuously filters the air whenever it's running. To get the best results, pay attention to the filters. First, replace them at least every six months (set a calendar reminder). Second, use the right kind of filter. "HEPA filters remove almost all particles from air that flows through them, but most residential HVAC systems aren't designed to use a HEPA filter," says Richard Corsi, Ph.D., dean of the Maseeh College of Engineering & Computer Science at Portland State University. If you can't use HEPA, research the filters you're considering. "Most air filters have a MERV [minimum efficiency reporting value] rating. The higher the number, the more particles a filter removes from the air. Go as high as your HVAC system can handle. Anything higher can damage the system." (The crew servicing your heater and AC can tell you.)

Also, if your system has a setting that runs the fan even if the AC or heat is off, think about turning it on so the air constantly recirculates through the filter.

4. You always keep windows closed.

Even a few minutes of fresh air can improve indoor air quality. Opening a window increases airflow, moving any pollution out. On high ozone days though, keep windows closed. Check the AirNow website to see current levels in your area.

However, if you have seasonal allergies, opening windows means letting pollen inside. You're much better off keeping things sealed off in the bedroom, where you spend so much time, and turning on the air-conditioner, says Tania Elliott, M.D., a spokesperson for the American College of Allergy, Asthma & Immunology (ACAAI).

5. You burn scented candles in closed rooms.

They smell good, but scented candles aren't great for air quality. That's because anything with a scent contains VOCs, or volatile organic compounds. "There are thousands of different VOCs. Some are harmless; others are pretty bad for you. And there isn't a simple way to tell one from the other," Collins says. "If VOC concentrations are high in your house, they can mix with other things in the air and form hazardous chemicals like formaldehyde."

Another downside: Many VOCs tend to stay inside, partly because of how well-sealed modern, energy-efficient homes are and partly due to the vapors clinging to walls and surfaces then slowly coming off into the air, says Delphine Farmer, Ph.D., associate professor of chemistry at Colorado State University. If you want to burn a favorite scented candle for a little bit, crack a nearby window. Unscented candles produce fewer VOCs, so they're not a big problem.

6. You overuse disinfectants.

Cleaning chemicals like ammonia, bleach, and hydrogen peroxide disinfect well but can irritate airways. Try to use them only when you need to disinfect and kill bacteria, and stick to one cleaner at a time (this prevents chemicals mixing in the air, which can dial up the toxicity). Open windows in the room you're cleaning, and leave after you're done so you're not inhaling fumes while the air clears. Also try to avoid lemon- or pine-scented cleaners; VOCs from those scents are especially reactive with other chemicals in the air. For general cleaning, consider using a natural product, something homemade with vinegar, or good old soapy water.

7. You mask odors with aerosol sprays.

Aerosol sprays quickly cover up icky odors, but beware: They put fine particulate matter into the air, which you inhale. "If you're not sensitive to essential oils, those are a better option," Shah says. "Lavender and peppermint are usually OK for most people." Add a drop or two to a diffuser or, in the bathroom, put a dab on the inside of the toilet paper roll. If you're sensitive to fragrance, choose fragrance-free products, not unscented ones, or crack a window to air out the room.

8. You don't ventilate when cooking.

"If you have a gas stove with an open flame, it emits carbon monoxide and nitrogen oxides, which are pollutants," Collins says. Although electric stoves and toaster ovens may not have an open flame, they still churn out particles you don't want to breathe in. That's why it's important to use ventilation while cooking. Check what kind of exhaust fan you have: The most effective type of vent filters the air and shuttles toxins outside. If yours recirculates the air instead, open a window.

9. Your shower curtain is made of PVC.

If you can't install a glass shower door, which is easier to keep clean, consider a shower curtain made with PEVA, which functions like vinyl but with none of the chemical off-gassing that PVC produces. "Wipe it with a damp cloth sprayed with a solution including hydrogen peroxide or thyme oil to kill bacteria and mold," says Leah Segedie, author of Green Enough: Eat Better, Live Cleaner, Be Happier. One catch: PEVA is made from petrochemicals, so "It's not the greenest option," she says. A better, more environmentally friendly choice is a shower curtain made from hemp, cotton, linen, or recycled sailcloth. Pull it closed (unbunched) after use to help it air-dry and wash it at least monthly.

10. You don't have a portable air cleaner.

When they first hit the market, stand-alone air filters got mixed reviews, but they have dramatically improved since then and can be a worthwhile investment. Do your homework to ensure you purchase a good model. "The higher the clean air delivery rate [CADR] on the portable HEPA filter, the better the system," Corsi says. Check that your unit's CADR is certified by the Association of Home Appliance Manufacturers, which also lists how much floor space units can handle. "A high-quality air cleaner can be expensive. But they're worthwhile and especially helpful for people with respiratory conditions," says Douglas Collins, Ph.D., assistant professor of chemistry at Bucknell University.