Third-trimester exposure to airborne particulate matter (PM) smaller than 2.5 mcm in size (PM2.5) has been linked to higher levels of systolic blood pressure during childhood.
Mingyu Zhang of Johns Hopkins Bloomberg School of Public Health, Baltimore, and his associates found that the highest tertile exposure was tied to an increased likelihood of childhood elevated BP, defined as systolic blood pressure higher than the 90th percentile, compared with those in the lowest tertile (relative risk, 1.60; 95% confidence interval, 1.12-2.27).
Previous studies have shown a relationship between exposure to PM2.5and elevated BP in children and adults. Mouse models suggest that PM2.5 may interfere with in utero development of the cardiovascular system. One previous study found evidence that third-trimester exposure to PM2.5was linked to heightened BP in newborns, while a retrospective analysis showed no association with BP in adolescents.
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They identified PM2.5 exposure by matching the mother’s residential address to the U.S. Environmental Protection Agency’s local air quality monitors, from which they extracted daily PM2.5 values.
For every 5 mcg/m3 increment in PM2.5 exposure, the relative risk for heightened BP in a child at a single visit was 1.46 (95% CI, 1.17-1.83). The relative risk increased after independent additions to the confounder model of birth weight (RR, 3.39; 95% CI, 0.63-6.15), gestational age (RR, 3.08; 95% CI, 0.33-5.82), and child body mass index (BMI) z score (RR, 2.75; 95% CI, 0.01-5.50).
A multivariable-adjusted cubic spline model revealed a significant increase in risk of elevated BP at a cutoff threshold of 13 mcg/m3 (RR, 1.80; 95% CI, 1.33-2.44).