title: Blood Pressure and Same-Day Exposure to Air Pollution at School: Associations with Nano-Sized to Coarse PM in Children.
abstract: BACKGROUND
  Ultrafine particles (UFP) may contribute to the cardiovascular effects of particulate air pollution, partly because of their relatively efficient alveolar deposition.
  
  
  OBJECTIVE
  In this study, we assessed associations between blood pressure and short-term exposure to air pollution in a population of schoolchildren.
  
  
  METHODS
  In 130 children (6-12 years of age), 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 schools' playground.
  
  
  RESULTS
  Independent of sex, age, height, and weight of the child, parental education, neighborhood socioeconomic 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-sized 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, but no effects on systolic blood pressure were found for the nano-sized fractions with a diameter > 100 nm, nor PM2.5, PMcoarse, and PM10. Diastolic blood pressure was not associated with any of the studied particulate mass fractions.
  
  
  CONCLUSIONS
  Children attending school on days with higher UFP concentrations (diameter < 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.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Nicky
authors.initials: N
authors.lastname: Pieters
authors.forename: Gudrun
authors.initials: G
authors.lastname: Koppen
authors.forename: Martine
authors.initials: M
authors.lastname: Van Poppel
authors.forename: Sofie
authors.initials: S
authors.lastname: De Prins
authors.forename: Bianca
authors.initials: B
authors.lastname: Cox
authors.forename: Evi
authors.initials: E
authors.lastname: Dons
authors.forename: Vera
authors.initials: V
authors.lastname: Nelen
authors.forename: Luc Int
authors.initials: LI
authors.lastname: Panis
authors.forename: Michelle
authors.initials: M
authors.lastname: Plusquin
authors.forename: Greet
authors.initials: G
authors.lastname: Schoeters
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
mesh_terms: D000397:Air Pollution / Q000009:adverse effects*; D001530:Belgium; D001794:Blood Pressure; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D053758:Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D012574:Schools; D012621:Seasons
chemical_list: D052638:Particulate Matter