Even short-term exposure to higher levels of air pollution may increase the likelihood that children with autism will be hospitalized for hyperactivity, aggression or self-injury, a new study suggests.

In a first-of-its-kind study, researchers looked at data on autism-related hospital admissions for children ages 5 to 14 between 2011 and 2015 in South Korea. They compared that information with national daily levels of fine particulate matter, nitrogen dioxide and ozone in the country’s 16 regions.

Hospital admissions for autism were 17% higher when fine particulate matter increased by 10 micrograms per cubic meter, according to findings published recently in the journal BMJ Open.

Similarly, when nitrogen dioxide or ozone grew by 10 parts per billion, hospitalizations for autism jumped by 9% and 3% respectively, the study found.

The impact on hospitalizations was more pronounced for boys than girls.

“This study suggests that short-term exposure to air pollution affects ASD symptom aggravation,” the researchers concluded. “These results (emphasize) that reduction of air pollution exposure should be considered for ASD symptom management, with important implications for the quality of life and economic costs.”

Previous research on autism and air pollution has focused on longer-term exposure during the prenatal period and during early development. The researchers note that brief exposure to higher levels of air pollution has been shown to increase the risk of hospitalization among those with psychiatric disorders, but that further study is needed to best understand any link with autism.