• Posted December 16, 2024

Prenatal Exposure to Air Pollution May Hurt Baby's Brain

Air pollution could be harming the brain development of children before they are even born, a new study warns.

A 10 parts-per-billion increase in ozone exposure during the second trimester of pregnancy was associated with a 55% increased risk of intellectual disability among children compared to their siblings, researchers found.

“Ozone exposure during pregnancy is a clear risk factor for intellectual disability,” said lead researcher Sara Grineski, a professor of sociology with the University of Utah.

“We were particularly struck by the consistency of the findings across all trimesters and the strength of the sibling-based analysis,” Grineski added in a university news release.

For the study, researchers analyzed data drawn from the Utah Population Database, a long-term research project into genetics and health among Utah residents. 

The team linked data on children with intellectual disabilities born between 2003 and 2013 to county-level daily estimates of ozone exposure gathered from the U.S. Environmental Protection Agency

In particular, the data allowed researchers to compare siblings born with different levels of exposure to ozone pollution, researchers said.

“Sibling designs allow us to control for some of these population factors that just would be really challenging to do,” said researcher Amanda Bakian, a research associate professor of psychiatry with the University of Utah’s Huntsman Mental Health Institute. “It just gives another layer of robustness of rigor to this study.”

Ozone is a harmful air pollutant caused when sunshine prompts a chemical reaction in airborne nitrogen and volatile organic compounds emitted from cars, power plants, refineries and other sources, researchers explained in background notes.

Ozone pollution is an increasing summertime hazard, particularly in the face of global warming, researchers said.

The second trimester showed the strongest associations between ozone exposure in the womb and a child’s future brain development.

During the second trimester, the fetal brain undergoes rapid growth, with neurons developing at a rate of 250,000 per minute, researchers said.

Federal health standards for ozone exposure is 70 parts per billion, researchers noted.

A 10 parts-per-billion increase in average ozone levels was associated with a 23% increased risk of intellectual disability when kids were compared to the population at large, and 55% higher when compared to their siblings, results show.

“When it comes to intellectual disability, we have a prevalence estimate of about 1.3% or so, and that has been pretty consistent over time,” Bakian said.

“That’s 1.3% of the kids that are born in any one year, and we still don’t have a great understanding of all the risk factors that are involved,” Bakian added. “What are the underlying mechanisms that drive this risk? Having intellectual disability has lifelong implications.”

The new study was published recently in the Journal of Exposure Science & Environmental Epidemiology.

Given these findings, places with lots of ozone pollution have a higher risk of kids with intellectual disabilities, researchers said.

“Salt Lake City ranks 10th for the most polluted cities in the U.S. in terms of ozone, and 2023 ozone levels were higher than 2022 levels,” Grineski noted.

Reducing ozone levels will be critical to protecting the brains of children, researchers said. Clean car standards, transitioning to electric vehicles and improving manufacturing and agricultural processes will help lower air pollution.

“We don’t want to neglect these issues related to ozone and cognitive health moving forward," Grineski said. "Our findings here for Utah suggest a troubling association. This is just one study in a sea of papers documenting the harmful effects of air pollution on health.”

More information

The U.S. Environmental Protection Agency has more about ozone pollution.

SOURCE: University of Utah, news release, Dec. 11, 2024