title: Air Pollution and Emergency Department Visits for Hypertension in Edmonton and Calgary, Canada: A Case-Crossover Study.
abstract: BACKGROUND
  Ambient air pollutant exposures have been associated with a wide variety of cardiovascular events; however, few studies have evaluated their impact upon acute emergency department (ED) visits for hypertension.
  
  
  METHODS
  The purpose of this study was to examine the associations between ED visits for hypertension and ambient air pollution concentrations among 6,532 patients during the period of January 2010 to December 2011 in Edmonton and Calgary, Alberta, Canada. The associations were evaluated using a case-crossover design.
  
  
  RESULTS
  Odds ratios and their 95% confidence interval have been calculated for 1 unit increase in their interquartile range for lags (the time between air pollutant measurement and exposure-response) 0-8 days. During the cold season, statistically significant positive results were observed for SO2 among lag days 4-6 and 8 for females and lag days 5 and 6 for males. Moreover, statistically significant positive results were observed for NO2 on lag day 7 for females and for PM2.5 on lag days 5 and 7, for females and lag day 6 for males. During the warm season, statistically significant positive results were observed for O3 on lag days 3 and 4 and for SO2 on lag days 2 and 8 for females.
  
  
  CONCLUSIONS
  These findings support the hypothesis that recent exposures to ambient levels of several air pollutants can be capable of elevating blood pressure to a clinically significant extent such that it leads to ED visits for hypertension.
authors: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA;
authors: Robert D
authors: RD
authors: Brook
authors: Department of Mathematics and Statistics, University of Ottawa, Ottawa, Ontario, Canada. tkousha@uottawa.ca.
authors: Termeh
authors: T
authors: Kousha
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D000416:Alberta / Q000453:epidemiology; D001794:Blood Pressure; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D018592:Cross-Over Studies; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D000393:Air Pollutants
keywords: Alberta; air pollution; blood pressure; case-crossover; emergency department visit; hypertension.