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Epidemiologic Notes and Reports Tornado Disaster -- Pennsylvania

On the afternoon and evening of May 31, 1985, 27 tornadoes swept across parts of Ohio, Pennsylvania, western New York, and Ontario, killing at least 91 persons, injuring more than 800 others, and leaving thousands more homeless. This disaster was the worst tornado storm in the United States since April 1974, when 315 people were killed by twisters that swept through 11 states, causing damage totaling more than $600 million.

In Pennsylvania, the hardest-hit state, these tornadoes resulted in 65 dead, 700 injured, 1,000 homes destroyed, and hundreds of millions of dollars in property damage. The 13 tornadoes that struck Pennsylvania ranged in speed from 75 mph to 250 mph, in width from 100 yards to 2 miles, and in distance on the ground from 4 to 56 miles. According to the Pennsylvania Emergency Management Agency, Pennsylvania has averaged eight tornadoes a year since 1953. The 1985 tornadoes were the worst to hit the state since record-keeping began in 1854. The worst previous tornado had been in June 1944, when 45 people were killed, 362 injured, and 800 homes damaged in the southwestern part of the state.

Previously, CDC evaluated tornado disasters in Texas (1), Illinois (2), and the Carolinas (3). These studies assessed various factors hypothesized to influence the risk of injury from tornadoes. For the Pennsylvania tornado disaster, a study was designed to document information on deaths and hospitalizations to evaluate selected factors that may influence why some people die from their injuries, while others do not. The study focused on five contiguous counties (Erie, Crawford, Mercer, Venango, and Forest) that were hardest hit (46 of the 65 fatalities). Due to the total relocation of highly affected neighborhoods and the inability to identify a representative sampling frame for uninjured persons in the immediate post-tornado period, the study looked at fatally injured and hospitalized injured persons. The latter were frequency matched to fatally injured persons 2:1 on two variables, tornado track and age stratum, and compared to detect risk factors for lethality. Public health nurses from the Pennsylvania Northwestern District Health Department were trained to use a standardized questionnaire and conducted the interviews in person whenever possible. Interviews were completed with respondents (next-of-kin, neighbor) for 89% of the fatally injured and with respondents (self, next-of-kin) for 90% of the hospitalized persons.

Certain demographic and impact-phase characteristics (age, sex, location, protective warning, and protective measures) have been found in previous studies to be risk factors for injury; however, in this study, these characteristics did not appear to explain severity of injury (Table 1). Assessment of injury outcome characteristics in this study revealed that fatally injured persons were more likely to sustain injuries to the head and/or neck than were seriously injured persons. Further review of fatally injured persons showed that all but a few appeared to have been killed "instantaneously" and did not die en route to or in hospitals. Reported by F Sellers, PhD, Northwest District, Meadville, D Reid, MD, AB Rakow, DO, JN Logue, DrPH, EJ Witte, VMD, State Epidemiologist, Pennsylvania Dept of Health; Div of Environmental Hazards and Health Effects, Center for Environmental Health, CDC.

Editorial Note

Editorial Note:Public health consequences of tornadoes are very important in the United States. During the 1970s, 507 tornado-related disasters resulted in 830 persons killed, 20,969 persons injured, and 490,316 persons treated with emergency care (4).

The present study shows that, for selected known risk factors, fatally injured persons did not differ significantly from seriously injured (hospitalized) persons. Since deaths were usually "instantaneous," differences among postevent factors, recovery/transport times, and efficacy of emergency medical care do not appear to have contributed to fatal outcome. More likely explanations include differences in amounts of mechanical energy impacting critical body parts and/or unrecognized preevent or event-phase risk factors. Future research and public health attention should be geared to such preventive activities as early warning and education.

Overall statistics showed that 52% of the persons both fatally and seriously injured had less than 1 minute's warning, and 65% had less than 5 minutes' warning. Furthermore, 31% of the initial warnings to seriously injured persons consisted of the person seeing or hearing the tornado, high winds, or flying debris. In some other tornado disasters, citizens have had earlier and more explicit warnings (1).

This study also showed that only 34% of the seriously injured persons knew the difference between a tornado warning and a tornado watch. Another study has shown that 36% of persons who sighted tornadoes did not know what they were (5).

Further emphasis needs to be placed on public health strategies for preventing or mitigating tornado-associated morbidity and mortality in high-risk areas. Community action programs should be oriented towards disseminating tornado warning/watches from the National Weather Service and tornado education for citizens. This tornado disaster, along with the majority of all tornadoes, occurred during the late afternoon when radio/television audiences are at their lowest (6). Therefore, utilization of positive alerts (sirens) are important.

Citizens should be taught what the warning systems are in their communities and what should be done when the warning systems are activated. They should know and practice the following safety measures:

  1. Persons in buildings should seek shelter indoors, on the lowest floor, preferably in a basement. Central rooms, including closets and stairwells, are safer than rooms along the outside of the house, and areas near windows should be avoided.

  2. Drivers should not attempt to drive away from a tornado. Instead, they should seek shelter indoors immediately on hearing a tornado warning.

  3. If drivers in open country cannot find indoor shelter, they should drive away from the tornado path at right angles. If there is not time to escape, persons outdoors should lie flat in the nearest ditch or ravine.

  4. Even properly anchored mobile homes are unsafe when wind speeds exceed 50 mph. In tornado-prone states, mobile-home parks should have alternative tornado shelters.


  1. Glass RI, Craven RB, Bregman DJ, et al. Injuries from the Wichita Falls tornado: implications for prevention. Science 1980;207:734-8.

  2. CDC. Assessment of tornado-related deaths and injuries--Marion, Illinois. Unpublished data, 1982.

  3. CDC. Tornado disaster--North Carolina, South Carolina, March 28, 1984. MMWR 1985;34:205-6, 211-2.

  4. American Red Cross. Special statistical summary--deaths, injuries, and property loss by type of disaster 1970-1980. In: Gordon PD. Federal Emergency Management Agency, April 1982.

  5. Wallace AFG. Tornado in Worcester. An exploratory study of individual and community behavior in an extreme situation. Washington, DC: National Academy of Science-National Research Council, 1956; publication 392.

  6. National Oceanic and Atmospheric Administration. The widespread tornado outbreak of April 3-4, 1974. A report to the Administrator. Rockville, Maryland: U.S. Department of Commerce, 1974; National Disaster Survey Report 74-1.

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