Scientists find more evidence that air pollution could cause autism.

Throughout the years, there have been many studies—some credible, some not—trying to figure out what causes autism. What is increasingly clear is the disease seems to occur when a child with a genetic predisposition is exposed to certain environmental factors within a specific timeframe. In the latest study to make the case, researchers from University of Southern California found a connection between autism and traffic-related air pollution.

In the new study published in the The Archives of General Psychiatry, researchers discovered that children who were born to mothers exposed to high levels of air pollution during pregnancy and who were themselves exposed to the highest levels of air pollution during the first year of life faced a more than twofold greater risk of being diagnosed with autism, a condition that now affects 1 in 88 children in the United States. "This is a highly credible study by very competent and respected researchers that further strengthens concern that environmental exposures contribute to the causation of autism," says autism expert Philip Landrigan, MD, professor of pediatrics and director of the Children's Environmental Health Center at Mount Sinai School of Medicine. He was not involved in this study.

This isn't the first time researchers have found a connection between air pollution and autism. In fact, particulate air pollution has been linked to the condition in previous studies. While researchers continue to try and tease out the details of exactly what causes autism—and how—there are plenty of other good reasons to avoid air pollution: It triggers heart attacks, stunts the growth of children, increases breast cancer risk, and is associated with anxious and depressed children.

Here are 3 easy ways to reduce your exposure to traffic-related air pollution:

1. If you can, work from home more often.

2. On high pollution days, close your windows and turn on your air conditioner. Make sure the model contains a clean HEPA filter.

3. Consider investing in a high-quality air purifier. Be careful, though. Some actually create ozone, a dangerous air pollution component that can damage your lungs. IQ Air has had favorable reviews in the past from reputable sources. And while inside, be sure to use nontoxic cleaners, preferably 9 parts water to one part white vinegar, to protect your indoor air.