Air pollution plays a role in the rising rate of autism among children in the U.S. and worldwide. According to the U.S. Centers for Disease Control, one in every 50 children in the U.S. has been diagnosed with autism. This is a 72% increase in the rate since 2007. The rate for boys is even higher. In areas with elevated pollution levels, autism rates are even higher than the national average. In New Jersey, for example, one in 48 children have autism. For boys in New Jersey, the rate is one in 28.

What is autism?

Autism and autism spectral disorder (ASD) are both terms for a variety of disorders affecting brain development. Those with autism may have problems with social interaction. They may lack verbal and nonverbal communication skills or exhibit repetitive behaviors. Many with autism excel in visual skills, music, math and art. A minority of autistic individuals have intellectual or other disabilities. There is no single cause of autism, “but it is generally accepted that it is caused by abnormalities in brain structure or function,” according to the Autism Society of America.

Autism awareness groups say most cases of autism involve a combination of a genetic predisposition and environmental factors. The age of a child’s parents at the time of conception can play a role. Illnesses during pregnancy can also affect the risk of a child being born with autism.

Air quality and autism

Environmental factors, including air quality, also play a role. A recent study from the University of Southern California found that children with a specific gene variant (known as the “MET gene”) who also lived in high pollution areas were three times more likely to develop autism than children without the gene and living in low-pollution areas.

In another recent study, researchers at Harvard University found a link between specific pollutants and autism. Women exposed to high levels of airborne diesel particulates or mercury while pregnant were twice as likely to have a child with autism. Women exposed to lead, manganese and methylene chloride were also more likely to have a child with autism. The risk for this group was not as high as for those exposed to diesel particulates and mercury. The researchers used air pollution data from the EPA to estimate women’s exposures while pregnant.

Steps to reduce environmental risk

Autism awareness groups say pregnant women should take steps to reduce exposure to chemicals and other pollutants associated with autism. This is especially important for women who live in areas with elevated pollution levels. Here are a few suggestions:

1. Mercury.Pregnant women should follow EPA and state guidelines on fish consumption. Avoid shark, swordfish, king mackerel, tile fish and large tuna. Some cosmetics may also contain mercury and should be avoided.
2. Lead.Avoid jobs or hobbies that may involve lead exposure, including exposure to dust from repairs and renovations in homes built before 1978. Also, avoid cosmetics, food additives or medicines from overseas.
3. Pesticides.Wash produce thoroughly before eating. Avoid using tick and flea collars for pets if the collars contain pesticides. Remove shoes before entering the home to avoid tracking in lawn and garden chemicals.
4. Endocrine-Disrupting Chemicals.This includes BPA and phthalates. Decrease consumption of processed and canned goods. Avoid foods or drinks in plastic containers with recycling codes #3, #4 and #7, as they may contain chemicals such as BPA.
5. Diesel particulates.The size of diesel particulates that are of greatest concern to human health are fine and ultrafine particles, according to the EPA. Avoid unnecessary exposure to traffic pollution, including sitting in an idling car when avoidable. Also, those who live or work close to a freeway should use a high performance air purifier to remove fine and ultrafine diesel particulates from the air.

Research suggests that women who take folic acid during early pregnancy may reduce their child’s risk of the most serious form of autism. However, experts point out that folic acid alone cannot prevent every child from developing autism.

For more information on autism, including additional ideas on how to avoid environmental hazards during pregnancy, visit the Autism Speaks website.