Prenatal Ozone Exposure and Risk of
Intellectual Disability in Children

Salt Lake City, Utah — A recent study conducted by researchers from the University of Utah has unveiled compelling evidence of a connection between prenatal exposure to ozone pollution and an increased risk of intellectual disability (ID) in children. Published in the Journal of Exposure Science & Environmental Epidemiology, the interdisciplinary research highlights critical implications for public health and environmental policy in Utah and beyond.

The study was led by sociology professor Dr. Sara E. Grineski, in collaboration with Dr. Timothy W. Collins, professor in the School of Environment, Society and Sustainability, Dr. Amanda Bakian, research associate professor in the Departments of Psychiatry, Dr. James VanDerslice, professor in the Department of Family and Preventative Medicine, as well as graduate student Roger Renteria and undergrad Camden J. Alexander, both from the Department of Sociology.

Their research utilized Utah’s Population Database and raw ozone data from the US EPA Downscaler spanning nearly two decades (2002-2020), allowing researchers to look at daily estimates of ozone for all census tracts in the US. From there, they were able to examine the dates in each child’s trimesters to calculate ozone exposure metrics unique to each child, based on when they were born, length of gestation, and where the mother lived at the time of birth. The findings offer new insights into how environmental pollutants can influence neurodevelopmental outcomes during pregnancy.

Key Findings
The study focused on ozone exposure during pregnancy, using exposure data linked to children with ID, their siblings, and population controls. Researchers discovered:

• Second Trimester Impact: The second trimester emerged as the most critical period for ozone exposure, with a 10 parts-per-billion (ppb) increase in average ozone levels associated with a 55.3% higher likelihood of ID compared to full siblings and a 22.8% increase compared to population controls.
• Consistent Risk Across Trimesters: Although the second trimester showed the strongest associations, exposures in all pregnancy stages correlated with elevated ID risk.
• Sibling Analysis Strength: Findings from sibling-comparison analyses were robust, demonstrating the validity of the results even when controlling for genetic and familial factors.

“This research emphasizes that ozone exposure during pregnancy is a clear risk factor for intellectual disability,” said Dr. Grineski. “We were particularly struck by the consistency of the findings across all trimesters and the strength of the sibling-based analysis.”

The research community has noted that current knowledge about ozone and cognitive health is insufficient, and that gaps with respect to ozone and cognition are perhaps widest for children. During the second trimester, the fetal brain undergoes rapid growth, with neurons developing at a rate of 250,000 per minute. Ozone’s potential interference with these processes, along with its impact on placental health, provides plausible mechanisms for the observed associations.

A Focus on Utah’s Air Quality
Utah’s Wasatch Front, which often experiences elevated ozone levels, provided a unique backdrop for the study. The findings underscore the potential impact of environmental pollutants on children’s health, especially given predictions that climate change will exacerbate ozone pollution.

“High ozone concentrations are a frequent problem in Utah. Salt Lake and Davis counties as well as portions of Weber, Tooele, Utah, Uintah, and Duchesne counties are often out of compliance with federal ozone standards. Salt Lake City ranks 10th for the most polluted cities in the US in terms of ozone, and 2023 ozone levels were higher than 2022 levels,” Dr. Grineski added.

Implications for Public Health and Policy
The study’s authors stress the importance of reducing ozone levels to protect vulnerable populations, particularly pregnant individuals. Public health measures such as implementing clean car standards, transitioning to electric vehicles, and updating manufacturing and agricultural processes are among the recommended strategies.

“The body of evidence suggests that it is important that we never take our foot off the gas in terms of working to reduce the levels of air pollution that Utahns are breathing,” said Dr. Grineski. “We don’t want to neglect these issues related to ozone and cognitive health moving forward. 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.”

This study highlights the need for further research into ozone exposure and neurodevelopmental outcomes. Dr. Grineski and her team hope their findings will encourage policymakers, public health officials, and the public to prioritize air quality improvements.

Research was supported by funding from the National Institute of Environmental Health Science, with collaborative support from the University of Utah, Intermountain Healthcare, Utah Registry of Autism and Developmental Disabilities, Utah Department of Health and Human Services, and the Pedigree and Population Resource.

Media contacts:

Andrew DeQuiroz
PR/Communications Manager
University of Utah College of Social and Behavioral Science

Andrew.dequiroz@csbs.utah.edu