The effect of evacuation on the number of victims following hazardous chemical release

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.