According to Autism Speaks, a new study found that children and adults diagnosed with autism spectrum disorder (ASD) has increased by 175% over a decade in the U.S. Now, new research reveals that the drastic rise may be linked to air pollution.

According to the Daily Mail, women who breathe polluted air during pregnancy have a higher risk of giving birth to a child with ASD. Research conducted by Israeli scientists found that babies who are genetically predisposed to autism and are exposed to four common pollutants were at greater risk of developing the disorder.

Haitham Amal, a world-leading expert in nitric oxide (NO) and brain disorders and the head of The Laboratory of Neuromics, Cell Signaling, and Translational Medicine at Hebrew University, has found that NO is a major culprit in ASD. NO is a gas released when cars burn fuel.

The researchers also noted that four components to air pollution, including small particulate matter of dust or smoke, sulfur dioxide, nitrogen oxides and ozone may also contribute to the development of ASD.

“Different kinds of neurological disorders, including autism spectrum disorder, can be associated with air pollutants,” said Amal, senior author of the study that was published in Brain Medicine. “The timing of exposure appears crucial, with heightened vulnerability during prenatal development.”

According to BBC Science Focus, it’s important to note that 80% of ASD cases are believed to be hereditary, so it’s the interaction between genetic and environmental factors that affects how many children develop the disorder.

Pollutants may be able to cross the placenta and affect the brain growth of the fetus suggest scientists, who have proposed pathways where they could disrupt the body. Previous research by Harvard scientists found that fine particulate matter found in air pollution increased the risk of ASD by 64% during early childhood and by 31% during prenatal periods. During the prenatal period, the greatest risk was found during the third trimester.

The new Israeli study comes at a critical time, as the American Lung Association reveals in its 2024 State of the Air report that 131.2 million people, or 39% of the U.S. population, live in areas with unhealthy levels of air pollution. This is an increase of 11.7 million people from the previous year's report.

Bakersfield, California is the most polluted city in the U.S. for year-round air quality. Other cities with poor air quality include Sacramento, California; Reno, Nevada; Eugene, Oregon; and Spokane, Washington.

The Israeli researchers theorize that ASD, a developmental disorder that affects how people interact, communicate and behave, may be the result of air pollution interfering with certain brain chemicals such as dopamine and norepinephrine. Pollutants may also cause nerve tissue inflammation during development, said the researchers.

But there is also the possibility that the increase in autism is due to more public awareness, Amal acknowledges. However, he says that his team has clearly found that NO plays a key role in autism.