title: Short-term effects of ambient air pollutants on asthma-related emergency department visits in Indianapolis, Indiana, 2007-2011.
abstract: OBJECTIVE
  We estimate the short-term associations between daily changes in ambient air pollutants and daily asthma-related emergency department (ED) visits in Indianapolis, IN.
  
  
  METHODS
  We identified asthma-related ED visits among Indianapolis residents aged ≥5 years. We used Poisson regression in a time-series framework to estimate the increased risk for asthma-related ED visits from exposure to ambient SO2, PM2.5 and ozone during the warm season (April-September) and SO2 and PM2.5 during the cold (October-March) season, from 2007 to 2011. Our models controlled for measured confounders, including weather and respiratory infections, as well as unmeasured confounders using a natural cubic spline to account for long-term seasonal trends.
  
  
  RESULTS
  During 2007-2011 in Indianapolis, 165,056 asthma-related ED visits occurred. We found statistically significant positive associations (p < 0.05) between ambient air pollutants and ED visits during the warm season for persons aged 5-44 years. Interquartile range increases in daily ozone concentrations with same day, 2-day lagged, and 3-day moving average were associated with increased risks for ED visits of 3.2% (95% CI: 0.2%, 6.3%), 4.4% (0.1%, 8.9%) and 4.8% (0.2%, 9.6%), respectively. Interquartile range increases in 3-day moving averages for SO2 were associated with an increased risk of 3.3% (95% CI: 0.2%, 6.5%). We identified statistically significant associations (p < 0.05) between increased SO2 and PM2.5 levels and decreased ED visits among some age groups, primarily during the cold season, and no significant positive associations between changes in PM2.5 concentration and asthma-related ED visits.
  
  
  CONCLUSIONS
  During the warm season, increases in ozone and SO2 concentrations were associated with increased asthma morbidity in children and young adults in Indianapolis. These results will enable reliable estimation of the health impacts of increases in these pollutants on asthma-related ED visits in Indianapolis and similar communities.
authors.affiliation: a Indiana Department of Environmental Management , Indianapolis , IN , USA .
authors.forename: Nathan
authors.initials: N
authors.lastname: Byers
authors.affiliation: b National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention , Atlanta , GA , USA .
authors.forename: Matthew
authors.initials: M
authors.lastname: Ritchey
authors.affiliation: c National Center for Environmental Health, Centers for Disease Control and Prevention , Atlanta , GA , USA , and.
authors.forename: Ambarish
authors.initials: A
authors.lastname: Vaidyanathan
authors.affiliation: d Indiana State Department of Health , Indianapolis , IN , USA.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Brandt
authors.affiliation: c National Center for Environmental Health, Centers for Disease Control and Prevention , Atlanta , GA , USA , and.
authors.forename: Fuyuen
authors.initials: F
authors.lastname: Yip
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis*; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D007196:Indiana; D008297:Male; D008875:Middle Aged; D010126:Ozone / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D012044:Regression Analysis; D012621:Seasons; D013458:Sulfur Dioxide / Q000032:analysis; D014887:Weather; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone
keywords: Lagged effects; ozone; particulate matter; sulfur dioxide; time-series