Air pollution can aggravate symptoms in autistic children, esp boys: Study

London, Sep 21: Autistic children who are exposed to air pollution for even relatively brief periods may be at higher risk of being admitted to hospital, with boys more at risk than girls, a study suggests.

The research, published in the journal BMJ Open, found that admissions for issues such as hyperactivity, aggression, or self-injury might be prevented by minimising these children's exposure to air pollution.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a range of symptoms and severity. It is often accompanied by neuroinflammation and systemic inflammation meaning drugs, supplements, and diet can improve the core symptoms. It is believed that short-term exposure to air pollution (days to weeks) can induce systemic inflammation and neuroinflammation, potentially increasing the risk of hospital admission in autistic people.

The researchers from Seoul National University Hospital, Korea, drew on official government data on daily hospital admissions for autism among children aged 5 to 14 between 2011 and 2015.

They collected information on national daily levels of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) in each of the 16 regions in the Republic of Korea for up to six days. The average daily number of hospital admissions for autism during the study period was 8.5 for autistic children and was much higher for boys (7) than for girls (1.6).

Analysis of the data showed that short-term exposure to PM2.5, NO2, and O3 was associated with a heightened risk of hospital admission for autism, and that boys were at greater risk than girls. A 10 microgrammes per cubic metre (µg/m3) increase in PM2.5 levels was associated with a 17 per cent higher risk of hospital admission for autism, the researchers said.

A 10 parts per billion increase in NO2, and O3 was associated with a 9 per cent and 3 per cent higher risk, respectively, they said. The researchers calculated that exposure to these pollutants was associated with a one-quartile increase, which corresponds to a 29 per cent higher risk of hospital admission for autism, with NO2 exerting the strongest effects, according to the researchers.

The team acknowledged that it used regional air pollution levels rather than individual ones, which could have affected the findings. Also, autistic children with mild symptoms might be less likely to receive psychiatric treatment and so might not have been included, they said.

“This study suggests that short-term exposure to air pollution affects ASD symptom aggravation, which is more prominent among boys than among girls," the researchers said. “These results emphasise that reduction of air pollution exposure should be considered for ASD symptom management, with important implications for the quality of life and economic costs,” they added.