Autism spectrum disorder (ASD) and other neurodevelopmental disorders could be triggered by air pollution, including the type emitted in car exhaust, a new study suggested — though it had some limitations.

The review, led by Hebrew University of Jerusalem, analyzed multiple studies related to autism and cellular activity. The findings were published in the journal Brain Medicine.

The researchers focused on four specific types of particles that make up air pollution: fine particulate matter (PM), nitrogen oxides (NO, NO2), sulfur dioxide (SO2) and ozone (O3).

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They also investigated four different ways in which these particles could impact the fetus.

Those four ways were neuroinflammation, oxidative/nitrosative stress (an imbalance of free radicals and antioxidants that causes cell damage), epigenetic modifications (chemical changes to DNA) and disruptions to certain neurotransmitters, according to the study.

“Increasing air pollution may significantly raise the risk of neurodevelopmental disorders, particularly ASD, due to gene-environment interactions,” lead study author Haitham Amal, PhD, an associate professor at The School of Pharmacy at Hebrew University of Jerusalem, told Fox News Digital.

“Key air pollutants — such as fine particulate matter, nitrogen oxides, sulfur dioxide and ozone — are implicated in triggering harmful processes in the brain, including neuroinflammation, oxidative stress and neurotransmitter imbalances,” he added. 

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The risk is highest during times of accelerated development, such as prenatal and early childhood periods, according to Amal, who is also a visiting professor at Boston Children’s Hospital within Harvard Medical School. 

“The brain starts developing at birth and continues to develop until the mid 20s,” Georges Ghacibeh, M.D., a neurologist at Hackensack University Medical Center in New Jersey, told Fox News Digital. He was not involved in the study. 

The risk is highest during times of accelerated development, such as prenatal and early childhood periods, the researcher said. (iStock)

“During the early years, from conception until about age 5, the brain undergoes the most changes and therefore is more susceptible to the impact of external factors,” added Ghacibeh.

In a previous study published in 2023, the same research team found that nitric oxide (NO), which is one of the particles in air pollution, is a “key pathological factor in autism,” Amal noted. 

The brain is most susceptible to external factors from conception until age 5, experts say.

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Ghacibeh agreed that air pollution could increase autism risk.

“Chemicals inhaled by a pregnant mother or a young child, if they enter the bloodstream and make it to the brain of the fetus or developing child, can affect various metabolic pathways, either by interfering directly with certain chemical reactions inside the cells, or by reducing the amount of oxygen delivered to the brain,” he told Fox News Digital. 

In the U.S., autism affects one in 36 children, or about 2.3%, as of 2024, according to statistics from the CDC. (iStock)

This can interrupt the process of normal brain development, according to the doctor, causing brain cells to lose their normal function. 

“The mechanism would be similar to the effect of certain medications ingested during pregnancy that can lead to developmental delay or autism in the child,” Ghacibeh said.

Study doesn’t prove cause

Amal acknowledged that the study had some limitations.

“The data is based on epidemiological studies,” he said. “Extensive experiments in our labs should be done to validate and prove this connection.”

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Ghacibeh agreed, noting that epidemiological studies prove association but not causality. 

“In other words, if two phenomena occur simultaneously, such as high levels of air pollution and a rise in autism, this does not necessarily prove that one caused the other — it just means that both phenomena occurred at the same time. It is possible that additional, unknown factors might have played a role as well,” he said.

Air pollution affects approximately 131.2 million people, or 39% of the U.S., as noted in the 2024 American Lung Association’s State of the Air report.  (iStock)

Future research should aim to better understand pollution’s effects on “genetically susceptible individuals” and to find ways to protect those at greatest risk, according to Amal.

“This knowledge could inform public health policies aimed at minimizing ASD risk from environmental pollutants,” he added.

In the U.S., autism affects one in 36 children, or about 2.3%, as of 2024, according to statistics from the Centers for Disease Control and Prevention (CDC). 

This is an increase from one in 44 children two years ago.

“Chemicals inhaled by a pregnant mother or a young child, if they enter the bloodstream and make it to the brain of the fetus or developing child, can affect various metabolic pathways,” an expert warned. (iStock)

Air pollution is also on the rise, affecting approximately 131.2 million people, or 39% of the U.S., as noted in the 2024 American Lung Association’s State of the Air report. 

This is an increase of 11.7 million people from 2023. 

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Living in areas with lower pollution levels — away from factories or airports, for example — could help to prevent potentially harmful effects of air pollution, Ghacibeh said.

“Increasing air pollution may significantly raise the risk of neurodevelopmental disorders, particularly ASD, due to gene-environment interactions,” the study researcher said. (iStock)

“Using good air filters, especially when you live in a higher-pollution environment, also helps mitigate those risks,” he added.

Good nutrition and limited exposure to smoking, alcohol and drugs also helps to promote optimal brain development and neurological health, according to Ghacibeh.

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The study was funded by grants from the U.S. Department of Defense (DoD) and the Eagles Autism Foundation, which raises funds for innovative research and care programs, according to its website, along with others.

Fox News Digital reached out to the Autism Foundation, Autism Spectrum Disorder Foundation and Autism Society for comment on the study.

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A teenager has been left in critical condition after contracting the first presumptive human case of avian influenza (H5N1, or bird flu) in Canada.

B.C. provincial health officer Dr. Bonnie Henry announced the patient’s status at a news conference Tuesday, noting that the teen was healthy “prior to this, so no underlying conditions.”

“It just reminds us that in young people, this is a virus that can progress and cause quite severe illness, and the deterioration that I mentioned was quite rapid,” she said.

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Canada’s Health Minister Mark Holland confirmed the first human case in a post on X last week.

“To date, there has been no evidence of person-to-person spread of the virus in any of the cases identified globally,” he wrote. “Based on current evidence in Canada, the risk to the general public remains low.”

Holland also noted that the Public Health Agency of Canada is working with the BC (British Columbia) Centre of Disease Control and Office of the Provincial Health Officer, and that the agencies “will remain in close contact to protect Canadians.”

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The BC government wrote in a press release last week that a “public-health investigation has been initiated to determine the source of exposure and identify any contacts.”

“The source of exposure is very likely to be an animal or bird, and is being investigated by B.C.’s chief veterinarian and public health teams,” the province stated.

Sam Scarpino, PhD, director of AI and life sciences at Northeastern University in Boston, said the potential H5N1 infection in Canada is “concerning” for two reasons.

“First, the individual is hospitalized, which suggests a more severe infection than we have typically seen in the U.S.,” he told Fox News Digital.

“Assuming they do not have underlying health conditions, it’s uncommon for teenagers to be hospitalized for an influenza infection.”

This also represents the first known locally acquired H5N1 infection in Canadian history, Scarpino noted.

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“Reading between the lines in the official press release from British Columbia, it sounds as though they have reason to suspect the hospitalized individual may have had recent contact with livestock and/or wildlife, suggesting they were infected via spillover from an animal host,” he said.

“However, if evidence emerges of possible human-to-human transmission, that would raise the threat level considerably.”

Evidence of potential human-to-human transmission of bird flu would “raise the threat level considerably,” Scarpino said. (iStock)

Regardless of how this infection occurred, Scarpino said, “It’s becoming more and more clear that H5N1 has become a persistent threat in North America.”

In the U.S., as of Nov. 8, there were a total of 46 confirmed reported human cases of bird flu, according to the Centers for Disease Control and Prevention (CDC).

A majority of the U.S. cases have been in California (21), Washington (11) and Colorado (10).

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Earlier this month, a CDC study revealed that among farm workers who were exposed to H5N1-infected dairy cattle, 7% had bird flu antibodies. This suggests that they were previously infected with the virus.

Based on these findings, the CDC is calling for “active monitoring of exposed workers and testing to detect and treat HPAI A(H5) infections, including those in persons with very mild symptoms.”

Last week, a CDC study revealed that among farm workers who were exposed to H5N1-infected dairy cattle, 7% had bird flu antibodies. (AP Photo/Vadim Ghirda, File)

The agency also recommends expanded access to personal protective equipment (PPE) for farm workers.

“It’s clear we need broader, more systematic serosurveillance efforts and to triangulate the results of those studies with clinical and wastewater surveillance data,” Scarpino told Fox News Digital. 

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“We also need to offer H5N1 vaccines to dairy farm workers and ensure they have access to proper PPE … We can’t afford to keep letting this virus spill over into humans,” he went on. 

“It’s only a matter of time before someone dies an unnecessary death and/or we start seeing human-to-human transmission.”