To evaluate the association of long-term ambient fine particulate matters (PM_2.5) exposure with elevated blood pressure in children.

From April 2012 to June 2013, we used cluster randomized sampling method to investigate 9 354 children aged 5-17 years old from 68 primary and middle schools in the seven Northeastern Cities (Shenyang, Dalian, Fushun, Anshan, Benxi, Liaoyang and Dandong) in Liaoning Province, and measured their blood pressure (BP). A spatial statistical model nested by aerosol optical depth (AOD) was used to inverse PM_2.5 concentrations. Generalized additive model was used to quantify the association between PM_2.5 exposure and blood pressure in children. To examine the associations, two-level regression model was used to evaluate individual characteristics′ modifying effect on the health influence of PM_2.5.

The prevalence of hypertension in children was 13.78% (1 289/9 354). The results showed that there was an associations between hypertension and pollutants, and the multivariable regression analysis indicated that the increase in mean systolic blood pressure (SBP), diastolic blood pressure (DBP), and the OR of hypertension associated with a 10 μg/m³ increase for PM₂.5 were 3.12 (95%CI: 2.71-3.54) mmHg (1 mmHg=0.133 kPa), 1.45 (95%CI:1.12-1.78) mmHg, and 1.55 (95%CI: 1.10-2.19), respectively. Compared with non-breastfeeding children (OR=2.10, 95%CI: 1.39-3.17), children who were breastfeeding (OR=1.49, 95%CI: 1.00-2.20) exhibited consistently weaker effects, and the interaction effect of P value was 0.002.

Study findings indicate that long-term exposure to PM_2.5 is associated with increased arterial BP and hypertension among the children. Breastfeeding may reduce this association.

Blood pressure; Child; PM₂.5