A new study has found that exposure to PM2.5 during early pregnancy is associated with higher blood pressure and an increased risk of hypertension in children aged 5 to 12 years old.
This research, published in the journal Environmental Research, is the largest of its kind in the United States and reinforces growing concerns about the lifelong health impacts of air pollution, starting from the womb.
The analysis, part of the National Institutes of Health’s ECHO Program, involved data from 4,863 children across 20 pregnancy cohorts across the US. Researchers used advanced spatiotemporal models to estimate mothers’ exposure to PM2.5 with biweekly precision during pregnancy.
A key discovery of the research points to early pregnancy as a particularly sensitive period. Specifically, higher maternal exposure to PM2.5 during the first trimester was associated with more pronounced systolic blood pressure and a greater likelihood of a child being classified as having high blood pressure.
It was found that for every 5 µg/m³ increase in PM2.5 during that window, there was a corresponding rise in a child’s systolic blood pressure percentile and a 16% higher risk of being classified as having high blood pressure in childhood.
The average PM2.5 exposure levels in the study were between 7.6 and 7.9 µg/m³, which are below the current U.S. annual regulatory standard of 12.0 µg/m³.
In a surprising turn of events, the study found that nitrogen dioxide had exactly the opposite effect. Higher prenatal exposure to NO₂ was linked to lower childhood blood pressure. The authors suggest this may be due to the complex chemistry of air pollution mixtures or other confounding factors not captured in the model, highlighting that pollutants do not act in isolation.
Childhood hypertension is a growing concern and children with elevated blood pressure are at a higher risk of heart disease and other chronic conditions later in life.
Study author Yu Ni, PhD, of San Diego State University, said: ‘These findings add to growing evidence that early-life exposure to fine particulate air pollution may affect children’s cardiometabolic health, even at relatively low levels.
‘The unexpected findings related to nitrogen dioxide suggest that more research is needed to understand how this type of air pollution may affect children’s developing bodies, as well as whether other environmental factors could be playing a role, such as transportation noise.’
The full research can be read here.
Photo: Natalia Marcelewicz / Unsplash
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