title: Effect of ambient air pollution on the incidence of appendicitis.
abstract: BACKGROUND
  The pathogenesis of appendicitis is unclear. We evaluated whether exposure to air pollution was associated with an increased incidence of appendicitis.
  
  
  METHODS
  We identified 5191 adults who had been admitted to hospital with appendicitis between Apr. 1, 1999, and Dec. 31, 2006. The air pollutants studied were ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and suspended particulate matter of less than 10 micro and less than 2.5 micro in diameter. We estimated the odds of appendicitis relative to short-term increases in concentrations of selected pollutants, alone and in combination, after controlling for temperature and relative humidity as well as the effects of age, sex and season.
  
  
  RESULTS
  An increase in the interquartile range of the 5-day average of ozone was associated with appendicitis (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.03-1.25). In summer (July-August), the effects were most pronounced for ozone (OR 1.32, 95% CI 1.10-1.57), sulfur dioxide (OR 1.30, 95% CI 1.03-1.63), nitrogen dioxide (OR 1.76, 95% CI 1.20-2.58), carbon monoxide (OR 1.35, 95% CI 1.01-1.80) and particulate matter less than 10 micro in diameter (OR 1.20, 95% CI 1.05-1.38). We observed a significant effect of the air pollutants in the summer months among men but not among women (e.g., OR for increase in the 5-day average of nitrogen dioxide 2.05, 95% CI 1.21-3.47, among men and 1.48, 95% CI 0.85-2.59, among women). The double-pollutant model of exposure to ozone and nitrogen dioxide in the summer months was associated with attenuation of the effects of ozone (OR 1.22, 95% CI 1.01-1.48) and nitrogen dioxide (OR 1.48, 95% CI 0.97-2.24).
  
  
  CONCLUSIONS
  Our findings suggest that some cases of appendicitis may be triggered by short-term exposure to air pollution. If these findings are confirmed, measures to improve air quality may help to decrease rates of appendicitis.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Calgary, Teaching Research and Wellness Center, Calgary, Alta. ggkaplan@ucalgary.ca
authors.forename: Gilaad G
authors.initials: GG
authors.lastname: Kaplan
authors.forename: Elijah
authors.initials: E
authors.lastname: Dixon
authors.forename: Remo
authors.initials: R
authors.lastname: Panaccione
authors.forename: Andrew
authors.initials: A
authors.lastname: Fong
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Szyszkowicz
authors.forename: Amanda
authors.initials: A
authors.lastname: Wheeler
authors.forename: Anthony
authors.initials: A
authors.lastname: MacLean
authors.forename: W Donald
authors.initials: WD
authors.lastname: Buie
authors.forename: Terry
authors.initials: T
authors.lastname: Leung
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Heitman
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Villeneuve
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D000416:Alberta / Q000453:epidemiology; D001062:Appendectomy / Q000379:methods; D001064:Appendicitis / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D016001:Confidence Intervals; D018592:Cross-Over Studies; D004784:Environmental Monitoring / Q000379:methods; D062665:Epidemiological Monitoring; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D008452:Maximum Allowable Concentration; D008875:Middle Aged; D016017:Odds Ratio; D052638:Particulate Matter / Q000009:adverse effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D012621:Seasons; D012720:Severity of Illness Index; D017678:Sex Distribution; D013997:Time Factors; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter