title: The effect of evacuation on the number of victims following hazardous chemical release.
abstract: OBJECTIVE
  In response to chemical releases, evacuation is considered an important strategy to limit victim exposure. To our knowledge, no previous studies have provided evidence-based information on the effect of evacuation on limiting the number of victims following a hazardous chemical release (HCR). This study attempts to evaluate the impact of evacuation on the number of victims resulting from different types of HCR.
  
  
  METHODS
  The Hazardous Substances Emergency Events Surveillance (HSEES) database was used to test the hypothesis that evacuation is associated with a reduced risk of victims resulting from a HCR. A series of logistic regression models were developed in which the presence or absence of a victim was the primary outcome, with the specific chemical agent as the predictor. Where possible, the dataset was adjusted for confounding factors. The analysis was then stratified by presence or absence of evacuation, and odds ratios were compared for specific hazardous chemicals across strata.
  
  
  RESULTS
  Of the recorded HCR events in our sample, 7.77% (2, 930 total evacuations) resulted in evacuation. Compared to no evacuation order, evacuation was associated with a significantly lower number of victims, per HCR, when the chemical involved was acid, ammonia, or chlorine.
  
  
  CONCLUSIONS
  Evacuation remains the mainstay for prehospital care to limit victims of a HCR. Our analysis suggests that some types of HCR events are associated with fewer victims when evacuation is ordered.
authors.affiliation: Department of Surgery, Division of Emergency Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Preston
authors.forename: David
authors.initials: D
authors.lastname: Marcozzi
authors.forename: Raquel
authors.initials: R
authors.lastname: Lima
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pietrobon
authors.forename: Larissa
authors.initials: L
authors.lastname: Braga
authors.forename: Danny
authors.initials: D
authors.lastname: Jacobs
mesh_terms: D016001:Confidence Intervals; D016208:Databases, Factual; D004632:Emergency Medical Services / Q000458:organization & administration*; D015386:Hazardous Substances / Q000009:adverse effects / Q000145:classification*; D006801:Humans; D054527:Mass Casualty Incidents; D011634:Public Health; D012036:Refugees / Q000706:statistics & numerical data; D012189:Retrospective Studies; D017751:Safety Management / Q000458:organization & administration* / Q000706:statistics & numerical data; D014187:Transportation of Patients; D014481:United States; D014483:United States Dept. of Health and Human Services
chemical_list: D015386:Hazardous Substances