Risk of Tornado-related Death and Injury in Oklahoma, May 3, 1999

Abstract

On May 3, 1999, powerful tornadoes, including a category F5 tornado, swept through Oklahoma. The authors examined all tornado-related deaths, hospital admissions, and emergency department visits to identify important risk factors. Data on deaths and injuries directly related to the tornadoes and information obtained from a survey of residents in the damage path of the F5 tornado were used in a case-control analysis. The direct force of the tornadoes caused 40 deaths, 133 hospital admissions, and 265 emergency department outpatient visits. The risk of death from the F5 tornado was greater for persons who were in mobile homes (odds ratio (OR) = 35.3, 95% confidence interval (CI): 7.8, 175.6) or outdoors (OR = 141.2, 95% CI: 15.9, 6,379.8) when the tornado struck than for those in permanently anchored houses. Risk of severe injury was also greater for persons in mobile homes (OR = 11.8, 95% CI: 3.4, 51.7) or outdoors (OR = 34.3, 95% CI: 4.4, 1,526.2). However, the risk of death (OR = 0.0, 95% CI: 0.0, 9.9), severe injury (OR = 0.0, 95% CI: 0.0, 2.0), or minor injury (OR = 0.8, 95% CI: 0.1, 3.1) was not greater among persons in motor vehicles than among those in houses. The risk of death (OR = 0.6, 95% CI: 0.1, 1.7), severe injury (OR = 0.2, 95% CI: 0.1, 0.6), or minor injury (OR = 0.3, 95% CI: 0.2, 0.7) was lower among those fleeing their homes in motor vehicles than among those remaining. Recommendations involving the relative safety of motor vehicles during a tornado should be evaluated using experience from recent tornado events.

Spatial Analyses of the 2011 Joplin Tornado Mortality: Deaths by Interpolated Damage Zones and Location of Victims

“…Tornado fatalities in the United States have been studied over time, by month, by time of day and the day of week, by state/region, by F scale or EF scale rating, by lead time, by place or location of death, by age and sex of the deceased, and so forth (e.g., Daley et al 2005;Ashley 2007;Wurman et al 2007;Simmons and Sutter 2008;Sutter and Simmons 2010;Sutter 2011, 2012;Simmons et al 2012). Simmons and Sutter (2011) have identified four major vulnerabilities for tornado casualties: tornadoes that occur overnight, tornados that occur during the fall/winter months, residence in a mobile home, and location in the United States (specifically, the southeastern part of the United States; see also Schmidlin et al 2009;Chaney and Weaver 2010).…”

“…If the path passes over highly populated areas, deaths are likely to be higher than if it passes over less populated areas. Tornado deaths also depend on the nature of tornado warnings and compliance with such warnings (Daley et al 2005 (Simmons and Sutter 2011). 3 The number of homes and businesses damaged or destroyed differs not only over time, but also from one source to another.…”

“…Available studies (e.g., Gruntfest 1987;Daley et al 2005) suggest that the vulnerabilities and effects of natural disasters are not distributed evenly by gender and age. Using NWS records on tornado victims from 1996 to 2007, Simmons and Sutter (2011) claim that fatalities are reasonably balanced between the sexes.…”

“…5 The percentage of fatalities in mobile homes compared to permanent homes is remarkable, because mobile homes accounted for only 7.6% of U.S. housing units in 2000, and only 6.9% of the population lives in mobile homes (Simmons and Sutter 2011). This clearly suggests that residents of mobile homes face a more significant risk of death than residents of permanent homes (Brooks and Doswell 2002;Brown et al 2002;Daley et al 2005).…”

Comments

“…But, Speheger et al (2002) found that only 13% of the total path area affected in the OKC tornado was associated with F4 or F5 damage levels, which is typical of the few F5 tornadoes whose paths have been surveyed reasonably thoroughly. Thus, the other estimates that include either destroyed homes or damaged or destroyed homes [i.e., the Oklahoma Department of Emergency Management, which counted destroyed housing, regardless of the F-scale rating, and Daley et al (2005), based on a survey of residents in damaged or destroyed housing in the path] more accurately reflect the distribution of damage in F5 tornadoes. These fatality rates range from 0.1% to 1%, which are one to two orders of magnitude less than those of W2007.…”