Blood Pressure and Same-Day Exposure to Air Pollution at School: Associations with Nano-Sized to Coarse PM in Children

Abstract

Ultrafine particles (UFP) may contribute to the cardiovascular effects of particulate air pollution, partly because of their relatively efficient alveolar deposition. In this study, we assessed associations between blood pressure and short-term exposure to air pollution in a population of school children. In 130 children (aged 6-12 years) blood pressure was determined during two periods (spring and fall 2011). We used mixed models to study the association between blood pressure and ambient concentrations of particulate matter and ultrafine particles measured in the schoolsˈ playground. Independent of gender, age, height and weight of the child, parental education, neighborhood socio-economic status, fish consumption, heart rate, school, day of the week, season, wind speed, relative humidity and temperature on the morning of examination, an interquartile range (860 particles/cm3) increase in nano UFP fraction (20-30 nm) was associated with a 6.35 mmHg (95% CI: 1.56, 11.14; p=0.01) increase in systolic blood pressure. For the total UFP fraction, systolic blood pressure was 0.79 mmHg (95% CI: 0.07, 1.51; p=0.03) higher, while no effects on systolic blood pressure were found for the nano-sized fractions with a diameter larger than 100 nm, nor PM2.5, PMcoarse and PM10. Diastolic blood pressure was not associated with any of the studied particulate mass fractions. Children attending school on days with higher UFP concentrations (diameter smaller than 100 nm) had higher systolic blood pressure. The association was dependent on UFP size, and there was no association with the PM2.5 mass concentration.