title: Traffic-related air pollution and acute changes in heart rate variability and respiratory function in urban cyclists.
abstract: BACKGROUND
  Few studies have examined the acute health effects of air pollution exposures experienced while cycling in traffic.
  
  
  OBJECTIVE
  We conducted a crossover study to examine the relationship between traffic pollution and acute changes in heart rate variability. We also collected spirometry and exhaled nitric oxide measures.
  
  
  METHODS
  Forty-two healthy adults cycled for 1 hr on high- and low-traffic routes as well as indoors. Health measures were collected before cycling and 1-4 hr after the start of cycling. Ultrafine particles (UFPs; ≤ 0.1 μm in aerodynamic diameter), particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5), black carbon, and volatile organic compounds were measured along each cycling route, and ambient nitrogen dioxide (NO2) and ozone (O3) levels were recorded from a fixed-site monitor. Mixed-effects models were used to estimate associations between air pollutants and changes in health outcome measures relative to precycling baseline values.
  
  
  RESULTS
  An interquartile range increase in UFP levels (18,200/cm3) was associated with a significant decrease in high-frequency power 4 hr after the start of cycling [β = -224 msec2; 95% confidence interval (CI), -386 to -63 msec2]. Ambient NO2 levels were inversely associated with the standard deviation of normal-to-normal (NN) intervals (β = -10 msec; 95% CI, -20 to -0.34 msec) and positively associated with the ratio of low-frequency to high-frequency power (β = 1.4; 95% CI, 0.35 to 2.5) 2 hr after the start of cycling. We also observed significant inverse associations between ambient O3 levels and the root mean square of successive differences in adjacent NN intervals 3 hr after the start of cycling.
  
  
  CONCLUSIONS
  Short-term exposures to traffic pollution may contribute to altered autonomic modulation of the heart in the hours immediately after cycling.
authors.affiliation: Air Health Sciences Division, Health Canada, Ottawa, Canada. scott.weichenthal@hc-sc.gc.ca
authors.forename: Scott
authors.initials: S
authors.lastname: Weichenthal
authors.forename: Ryan
authors.initials: R
authors.lastname: Kulka
authors.forename: Aimee
authors.initials: A
authors.lastname: Dubeau
authors.forename: Christina
authors.initials: C
authors.lastname: Martin
authors.forename: Daniel
authors.initials: D
authors.lastname: Wang
authors.forename: Robert
authors.initials: R
authors.lastname: Dales
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D018592:Cross-Over Studies; D004784:Environmental Monitoring; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000187:drug effects; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000633:toxicity; D010126:Ozone / Q000633:toxicity; D052638:Particulate Matter / Q000633:toxicity; D012119:Respiration / Q000187:drug effects; D012129:Respiratory Function Tests; D001335:Vehicle Emissions / Q000633:toxicity; D014797:Vital Capacity / Q000187:drug effects; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D001335:Vehicle Emissions; D010126:Ozone; D009585:Nitrogen Dioxide