It's not just adults who get anxious and depressed by all those cars on the roadways.

When a child gets diagnosed with behavioral problems, all too often parents look to their child's immediate environment to find causes or potential solutions. But a growing body of research is finding that the cause could be months or even years behind them. Exposures to endocrine-disrupting chemicals such as BPA and phthalates while a baby is still in the womb can interfere with brain development, leading to behavioral problems during childhood.

You can add air pollution to that list of damaging exposures. A new study published today in the journal Environmental Health Perspectives points the finger at polycyclic aromatic hydrocarbons, or PAHs, which are created when oil, coal, gasoline, and other fossil fuels are burned. They also exist in cigarette smoke, food that's been blackened or charred over charcoal, the coal-tar sealants used on driveways and parking lots, and, to a lesser extent, candles made from petroleum-based paraffin wax.

The new study was based on data collected from a larger-scale analysis of mothers living in New York City and their children. While pregnant, the mothers wore air-pollution-monitoring devices, and they provided samples of their own blood and blood from their babies' umbilical cords after birth. When the children were between the ages of 6 and 8 years old, they took psychological tests.

Mothers who had had higher levels of PAH exposure had children who exhibited more symptoms of anxiety and depression in the psychological tests when they turned 6. Those same moms had PAH exposure levels that you might expect of anyone living in a large urban area, and were not unusually high, says Frederica P. Perera, PhD, director of the Columbia Center for Children's Environmental Health, also in New York, who conducted the study. "Outdoor pollution penetrates quite readily indoors," she adds.

Though urban areas are the most heavily polluted, your home—and your body—can still be polluted with PAHs from tobacco smoke (if you allow that in your house), food, and cooking, even if you don't live in the city. Charred meats contain high levels of PAHs, and cooking oils that aren't designed for high heats, for instance, margarine and vegetable oil, release PAHs when they're overheated. "The proportion of the total PAH that is contributed by any one source will vary according to factors like location of residence and whether there are smokers in the home," says Perera, adding that none of the women in her study smoked.

Unfortunately, PAHs in air aren't regulated. The Environmental Protection Agency sets maximum limits for PAH levels in drinking water, but as far as your lungs are concerned, it's up to you to keep them clean.

Here's what you can do about it:

• Ban smoking in your home. A good idea for innumerable reasons.

• Consider air filters. If you're pregnant and live near a busy roadway, buy an air filter designed to remove ultrafine particles, which would help remove airborne chemicals that fall under the umbrella of PAHs.

• Don't char your meats. With warm weather coming early, chances are your grill will be getting an extra workout this summer. Any cooking method that exposes meats to smoke or hot metal contributes to PAH formation. Keep the PAHs to a minimum by not letting your meats get that blackened char on the exterior and by keeping a piece of foil between the meat and the grill. If you do get any blackened bits on your meat, scrape them off before you eat it.

• Rip up your driveway. The coal-tar sealants used on driveways and other paved surfaces have high PAH levels that you track indoors on your shoes. Pull up your driveway and repave it with permeable stone or concrete. Want a cheaper solution? Insist that everyone leave his or her shoes by the front door.

• Burn cleaner candles. Likely a small source of PAH exposure, paraffin-wax candles do release PAHs into your indoor air. Help your lungs out and switch to clean-burning beeswax, for less-polluting ambiance.