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Tornado Disaster -- Illinois, 1990

MMWR 40(2);33-36

Publication date: 01/18/1991

Table of Contents


Editorial Note




On August 28, 1990, from 3:15 to 3:45 p.m., the strongest tornado in northern Illinois in greater than 20 years struck the towns of Plainfield, Crest Hill, and Joliet in Will County. As a result of the storm's impact phase, 302 persons were injured (28 fatally). This report summarizes an investigation of injuries and deaths that resulted from the tornado's impact.

The tornado's path was up to -mile wide and 16.5 miles long; wind speeds were greater than 260 mph. National Weather Service criteria for issuing a tornado warning were not satisfied until the tornado had already touched the ground. Electrical power service to 65,000 customers and phone service to 10,000 residences were severed; in addition, the tornado destroyed three schools, a church, many businesses, 106 apartment units, and 470 single-family dwellings. The estimated cost of damages was $200 million (Will County Emergency Services Disaster Agency, unpublished data, 1990). Because no warning was provided, few persons sought a tornado shelter.

The investigation included a review of 350 emergency-room and inpatient medical records from eight hospitals to identify injuries sustained during the impact phase and the postimpact phase of the tornado. Ninety percent of affected persons were white and lived in predominantly residential subdivisions in three communities (1). Because many persons who were rendered homeless by the tornado relocated with relatives living in the area, more than 84% of the victims who sought medical care at hospitals could be contacted for telephone interviews.

An impact-related injury or death was defined as an injury or death caused by the direct mechanical effects of the tornado. Postimpact injuries were defined as injuries that would not have occurred in the absence of the tornado and that occurred within a 48-hour period following the tornado (e.g., from walking through the debris or cleaning up debris).

While most impact-related deaths occurred instantaneously, four persons with impact-related injuries died 2-8 weeks after the tornado. Of these four, one man died 8 weeks later from complications of chest trauma suffered during the impact phase.

Most (221 (63%) of 350) victims were treated initially at one of the eight hospitals; several of the more severely injured were transferred to tertiary-care facilities in other areas. Because the disaster occurred simultaneously with the change of work shifts for the nursing staff, approximately twice as many persons were available as would be expected in an average staffing pattern for that hospital; many physicians and off-duty nurses also volunteered services.

Of the 28 persons who died from impact-related injuries, eight were less than 20 years of age (range: 1 month-69 years; mean: 34 years); 14 were male (Table 1). Seven persons died in one large apartment complex; eight, in vehicles; five, in schools; four, in houses; and two, outside. Three persons died at one high school, where greater than or equal to 10 students crouched against the only hallway wall that did not collapse and, therefore, may have been protected from fatal or severe injury.

Reported by: Staffs of the following hospitals: St. Joseph Medical Center, Silver Cross Hospital, Joliet; Loyola Univ Medical Center, Maywood; Christ Hospital and Medical Center, Oak Lawn; Copley Memorial Hospital, Aurora; Edward Hospital, Naperville; Palos Community Hospital, Palos Heights; Morris Hospital, Morris. R Empereur, G Wold, Will County Health Dept; D Krieger, J Sapala, MD, Will County Coroner's Office; Illinois Emergency Svcs Disaster Agency; ML England, MS, BJ Francis, MD, State Epidemiologist, Illinois Dept of Public Health. Disaster Health Svcs, American Red Cross, Washington, DC. Health Studies Br, Div of Environmental Hazards and Health Effects, Center for Environmental Health and Injury Control, CDC.

Editorial Note

Editorial Note: Tornadoes are one of the most lethal and violent of all natural atmospheric phenomena (2). Tornadoes usually appear as rotating, funnel-shaped clouds that extend toward the ground from the base of thunderclouds with whirling winds of high velocity. The wind clouds rotate around a hollow cavity in which centrifugal forces produce a partial vacuum (3). Severe tornadoes may be greater than 0.6 miles wide, travel as far as 185 miles, and attain wind speeds of up to 310 mph. In the United States, the frequency of tornadoes varies by season: most occur from April through July during the late afternoon. Each year, almost 700 tornadoes occur in the United States; however, only about 3% result in casualties (3). Since 1950, tornado-related deaths have declined substantially because of improved warning systems and public response to warnings. Nevertheless, from 1953 through 1989, 3522 persons died as a result of tornadoes in the United States (4).

The tornado in Will County was atypical for several reasons. First, it was not characterized by a classic funnel appearance; instead, eyewitnesses described it as having a wall-like appearance. Second, it occurred in late August; 75% of tornadoes and almost all tornado-related fatalities occur by late July. Third, the Will County tornado approached from northwest to southeast; most tornadoes follow a southwest to northeast path (5). Fourth, it did not weaken or leave the ground for the entire 16.4 miles of its path. Finally, this tornado attained a rating of 5 on the Fujita scale--the maximum intensity for a tornado; based on this rating, the Will County tornado is among the highest 3% of the most violent tornadoes in U.S. history.

Because the tornado developed extremely rapidly, it was not detected by the conventional radar systems in use; a more sensitive Doppler radar was not in use because of a previous malfunction. The affected area was served by two emergency warning sirens; however, because official tornado spotters had not observed funnel clouds, the sirens were sounded only after the tornado began its destructive course through the town of Plainfield. A new radar system (NEXRAD (Next Generation Weather Radar)) to be installed in this area in 1992 uses Doppler and computer technology; tornado forecasting accuracy is expected to increase 66%.

Based on studies of previous tornadoes, persons aged greater than 60 years are seven times more likely to be injured than persons aged less than 20 years because of factors such as medical illnesses, decreased mobility, decreased ability to comprehend and rapidly act on tornado warnings, and greater susceptibility to injury (6). In Will County, the relatively higher proportion of deaths and injuries among persons less than 20 years of age (37.9%) than among those greater than 65 years (9.7%) may reflect both the population at risk (primarily a suburban, family-oriented community, with a median age of 27.5 years), the time of day (3:15 p.m., when homemakers and young children are at home), and the absence of warning. Compared with minor injuries, the risk for death may have been greater for persons aged greater than 65 years than for those aged less than 20 years (odds ratio=2.5; 95% confidence interval=0.5-10.9).

Based on previous studies, recommendations to reduce the risk for injury include seeking shelter indoors in the basement, on the lowest floor, or in a centrally located room; identifying shelters before a disaster; and using blankets or other materials for protection from flying objects (6-10). In addition, tornado-related morbidity and mortality may be reduced by 1) instituting improved early warning systems and methods of detecting tornadoes in all highly tornado-prone areas; 2) constructing tornado-resistant buildings or shelters; and 3) promoting behaviors that maximize the possibility of survival when a tornado strikes.



  1. Bureau of the Census. 1980 Census of population: characteristics of the population--general social and economic characteristics, Illinois. Washington, DC: US Department of Commerce, Bureau of the Census, 1983; report PC80-1-C15.
  2. National Research Council. Confronting natural disasters: an international decade for natural disaster reduction. Washington, DC: National Academy Press, 1987.
  3. Sanderson LM. Tornadoes. In: Gregg MB, ed. The public health consequences of disasters 1989. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1989:39-49.
  4. National Climatic Data Center. National summary of tornadoes 1989. Asheville, North Carolina: National Climatic Data Center, 1989. (Storm data; vol 31, no. 12).
  5. Fujita TT. U.S. tornadoes, part one: 70-year statistics. Chicago: The University of Chicago, Department of the Geophysical Sciences, 1987:103.
  6. Glass RI, Craven RB, Bregman DJ, et al. Injuries from the Wichita Falls tornado: implications for prevention. Science 1980;207:734-8.
  7. Duclos PJ, Ing RT. Injuries and risk factors for injuries from the 29 May 1982 tornado, Marion, Illinois. Int J Epidemiol 1989;18:213-9.
  8. CDC. Tornado disaster--Pennsylvania. MMWR 1986;35:233-5.
  9. CDC. Tornado disaster--North Carolina, South Carolina, March 28, 1984. MMWR 1985;34:205-6,211-3.
  10. Koehler UF. Designing for tornado safety: structural failure and occupant behaviour. Journal of Architectural Research 1976:10-1.


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