Warnings Heard and Protective Behaviors Taken By Individuals During the Historic Tornados — Alabama, April 2011

Warnings Received and Protective Behaviors Taken By Individuals During the April 27, 2011 Tornado Outbreak in Alabama

CDR Rebecca S. Noe MN, MPH, FNP, CDR David Sugerman MD, MPH, Amy F Wolkin MSPH

This session will present findings from two epidemiologic studies in Alabama following the April 27, 2011 tornados. The Centers for Disease Control and Prevention (CDC) conducted a descriptive study of fatalities and a case-control study of persons hospitalized with injuries. This session will highlight the warnings received and behaviors taken in response to the approaching tornados.

Of the 247 fatalities, at least 102 (41.3%) of the deceased received some form of warning; the most common warning mechanisms were word of mouth (n=26, 25.5%) and hearing a siren (n=15, 14.7%). Of those who heard a warning, 59 (59.7%) took protective action after hearing a warning, including taking shelter in CDC recommended locations (e.g., interior room, bathroom) in their homes (n=44).

The second epidemiologic study was a case-control telephone survey of 98 tornado injury cases from the April 27, 2011 event treated in the Alabama hospital system along with 200 uninjured community controls. After controlling for age, sex, race in a logistic regression analysis, the odds of being injured were lower for those who received warnings via the Internet (aOR, 0.20; 95% CI: 0.09-0.49), NOAA weather radio (aOR, 0.40; 95% CI: 0.19-0.84), television (aOR, 0.45; 95% CI: 0.24-0.83), and sirens (aOR, 0.50; 95% CI: 0.30-0.85) compared to 23 (23.5%) cases and 35 (17.5%) controls who did not receive a warning. Among those who reacted to sirens on the day of the event, seeking further information was the only action significantly associated with lower odds of injury (aOR, 0.41; 95% CI, 0.18-0.93). Being located in a mobile home at the time of tornado impact compared to a permanent residence (e.g., homes with a foundation) had the greatest odds of injury (odds ratio [OR], 9.06; 95% confidence interval [CI]: 1.12–73.40). Within all types of residences, location in a basement (OR, 0.15; 95% CI, 0.04–0.59), bathroom (OR, 0.25; 95% CI: 0.05–1.31), or closet (OR, 0.18; 95% CI, 0.04–0.76) had significantly lower odds for injury compared to being in a living room, kitchen, or family room.

In summary, many people in the path of the April 27, 2011 tornados received warnings through multiple communication channels. Discovered protective behaviors included people sheltering in recommended places (e.g., closet, bathroom, and basement) and seeking more information. Finally, tornado messages should encourage specific protective behaviors such as seek cover in a safe location such as a safe room, basement, and if possible, avoid sheltering in trailers.