We think of outdoor air quality most often, but indoor pollution is a hazard, too

A truck spewing exhaust prompts many of us to hold our breath when it passes by on the street. But when it comes to pollution, your own home might be just as insidious.

People spend 90 percent of their time indoors, and your home can be two to five times as polluted as the air outside, according to the Environmental Protection Agency. Poor indoor air quality can cause health problems like asthma or sinus issues. And a lot of those problems are triggered by what is in your house, including cleaning products, furniture and carpets. "Taking care to recognize your house is properly ventilated and minimizing toxins you're bringing into your home and in your shopping bag is important," said Thor Peterson, the Residential Green Building Specialist with Seattle Department of Planning and Development.

It's not pretty once you break it down. Mold grows as a result of too much moisture, dust mites set up camp in pillows and mattresses, and outdoor grime and pollution are tracked in on your shoes. Your furniture might be off-gassing formaldehyde and, if not stored properly, paint cans are probably leaking volatile organic compounds, which can cause nose and lung irritation, rashes and headaches.

It gets worse in the winter, when people shut windows and seal their homes up to be energy efficient and trap everything inside.

Stop smoking, for starters

So what can you do to minimize your exposure?

For smokers, the No. 1 thing is to stop smoking at home, said Aileen Gagney, asthma and environmental health program manager for the American Lung Association of Washington.

For everyone, there are a few easy steps to get started: Use fewer chemicals, stop wearing shoes in your home and open windows even in winter.

"With all these chemicals, we're really torturing our lungs," Gagney said. "It's invisible, the air is invisible, but boy, are they [lungs] important."

To make your home even healthier, see the home-improvement tips below:

Easy improvements

Check your ventilation. Moisture results in mold, particularly in the bathroom. Test your bathroom's ventilation by placing a sheet of paper against a working fan. If the paper sticks, the fan is strong enough. If not, the motor might be old or the ducts may need work. Also, make sure air vents to the outside, not into the attic.

Keep dry. Make sure the crawl space is maintained and dry, that water spouts are directed away from the house's foundation and that the ground is graded to drain away from the foundation. Keep gutters clean and clear to keep water out of the house.

Buy a good vacuum. Air-quality experts dislike carpeting in general, but if you have carpeting, use a vacuum with a HEPA (high efficiency particulate air) filter and a dirt sensor, a light that lets you know when all the particles from a patch of carpet are vacuumed. "A lot of times, people do not vacuum as long as they need to," Peterson said.

The fewer cleaning products, the better. Castile (vegetable oil) soap, vinegar and baking soda will take care of most cleaning duties at home, Peterson said. If you still want to buy products, look for those with the Good Housekeeping Seal of Approval (www.goodhousekeepingseal.com), which usually are less toxic and work better.

The Washington Toxics Coalition Web site (www.watoxics.org) has information on toxins in the home, and Green Seal (www.greenseal.org) is another organization that evaluates household products for their environmental impact and toxicity.

One easy way to reduce toxins is to pick cleaning products without hazard warnings on them, Peterson said.

"If it says 'caution' or 'danger,' it's telling you there are toxins in the product," he said.

But Gagney recommends helping the environment by using up what you already have instead of tossing it, then switching to safer products.

Prevent lead paint exposure. Homes built before 1978 generally have lead-based paints, which produce lead dust when they chip, Peterson said. Wipe down surfaces in your home weekly with a lightly dampened cloth to minimize dust.

Fireplace. Woodburning fireplaces are probably one of the biggest pollutants in your home in the winter, Gagney said. Fires spew carcinogens and carbon monoxide into the air, and wood smoke damages lungs.

Eliminate dust mites. Dust mites like warm, moist places like pillows, but also live in furniture. Vacuum upholstered furniture, buy covers for your mattress and pillows and wash your sheets weekly in hot water. The water must be 130 degrees to kill dust mites, Gagney said, so if your water heater is set lower, increase the temperature about an hour before doing your laundry, or add a kettle of boiling water to the load.

Lock toxic compounds in a cabinet. Paints will leach volatile organic compounds once they're opened, as will other smelly household products. Either use them up when you buy them, or place them in a locked cabinet in a ventilated area like the garage.

Change filters. The EPA recommends changing filters on central heating and cooling systems and air cleaners according to manufacturer recommendations. If instructions are not available, change every month or two. Write down the old filter's model number and size before heading to the store.

Major changes

Replace carpeting. Carpeting picks up and holds on to dirt and toxins, and adhesives used to put the carpet together off-gas VOCs. Experts recommend installing as much hard flooring as you can, but if you still want carpet, natural materials like wool are better than synthetics. If you buy synthetic carpeting, ask the installer to unroll the carpet in the factory 48 hours before installing to let the adhesives dry. To find carpets with lower levels of off-gassing, see greenseal.org.

Pick safer floor finishes. Floor finishes often contain high levels of VOCs, so you should choose water-based finishes, which are less toxic than oil-based versions. You also might consider finishes that don't contain carcinogens or toxins, zinc or ammonia and have a VOC concentration of a maximum 7 percent by weight, according to Green Seal.

Seal exposed composite woods. Particle board and medium-density fiberboard are made with formaldehyde-based resins.

Formaldehyde is considered a probable human carcinogen, and it can cause respiratory problems and off-gasses for years, Peterson said. Countertops, cabinets and desks usually include some kind of composite wood inside.

If composite wood is made for exterior use, it is most likely sealed and safe, Peterson said.

If it is installed inside a cabinet, and part of the wood is exposed, it probably is off-gassing into your home. Look underneath desks, in bookshelves, inside cabinets and under countertops. If there is exposed composite wood, you should seal it, experts say. Peterson recommends Safecoat, a special sealant that locks in gas.

The Ikea factor. Sweden-based Ikea is required to adhere to stricter European standards for toxins, and has phased out fire retardants and uses low formaldehyde-based resins. It is one of the best sources for low-cost flooring and furniture that is safer for indoor air quality, Peterson and Gagney said.