Factors associated with injuries among tornado victims in Yancheng and Chifeng, China

Tornadoes are amongst the deadliest natural disasters and pose a major threat to worldwide public health. Between 1950 and 1994, over 4115 deaths and 70,063 injuries were reported as directly related to tornadic storms in the United States, with over 20 trillion US dollars’ worth of tornado-related damage [1].

Recent years, two violent tornadoes struck China, which caused massive loss of life and economic damage (Fig. 1). In the afternoon on June 23, 2016, an Enhanced Fujita 4 (EF-4) tornado tore through Yancheng City, Jiangsu Province, east China, with highest speed of 266 km/h (Enhanced Fujita scale categories for tornadoes range from 0 to 5, with the strongest being 5) [2, 3] (Fig. 1). The tornado affected 7 townships and 22 villages, resulting in 99 deaths and 846 wounded. In total, 29,371 houses, 2 primary schools, and 8 factories were damaged; more than 50,000 people were directly affected by the tornado [4]. This tornado was one of the largest disasters in recent decades in Jiangsu Province, and the deadliest tornado in China in nearly half a century [2, 5]. In the afternoon on August 11, 2017, a Fujita 3 (F-3, which is similar to EF-3) [6] tornado hit Keshiketeng County and Wengniute County in Chifeng City, Inner Mongolia (Fig. 1). This tornado affected 4 villages in 2 townships, causing 5 deaths and leaving 58 wounded. More than 30 houses collapsed, more than 2000 households were affected, and 1238 people were relocated [7].

At present, the research on the causes of the injuries and deaths caused by tornadoes mainly focuses on demographic factors, individual behaviors, architectural factors, and early warning information [8, 9]. For example, some studies [10‐12] argue that old people are more vulnerable to injury in tornadoes. Maybe it is because their body is weaker and their movement ability is worse. Female was thought to be more vulnerable to injury [10, 11]. There are few studies on disaster avoidance behaviors, and there are controversies about the impact of fleeing by motor vehicle on injuries [1, 13‐15]. Having safe helmet or car seats was a protective measure for children. Research shows that the majority of casualties are caused by the collapse of buildings and blunt force trauma from heavy objects [8, 11, 14]. Building with windows [12], or made by wood [1], or mobile car-house [13] increased the injury risk [1, 12]. However, sturdy shelter decreased the injury risk [13, 14]. Staying outside increased the injury risk [10], and basement of a house was a protective measure for residents [13]. That receipt of tornado warnings can reduce casualties [12, 13, 16]. However, at present China’s research on these aspects, especially pertaining to the complicated factors associated with tornado casualties, is basically non-existent.

Tornadoes in China mostly happen in coastal areas such as the Yangtze River Delta and Pearl River Delta [17]. These areas are densely populated with a high level of economic development, and therefore have the potential for mass casualties and huge economic losses. In terms of human characteristics, building environment, disaster prevention capabilities, tornadoes happened in China contribute to varying casualty results. Therefore, from the perspective of casualty prevention, it is especially important to analyze the factors influencing tornado injuries in China and reduce the probability of injuries by improving tornado casualty prevention and reduction. This study intends to analyze the factors influencing injury occurrences during the Yancheng tornado on June 23, 2016 and the Chifeng tornado on August 11, 2017; the factors that are herein examined include demographic characteristics, disaster environment, and individual behaviors. The study will provide clarification of risk factors and expand the research on tornado casualties.

The respondents include victims from two separate tornado disaster events in China. There are three reasons we chose Yancheng and Chifeng. First, the two cities vary geographically. Chifeng is located in the highland part of Inner Mongolia, whereas Yancheng is located in the plains. Second, the structure of buildings differs between the two cities. The buildings in Yancheng consist of brick and cement, while they are made of mud tiles in Chifeng. Third, Yancheng has a much higher population density than Chifeng. In addition, these were the only areas in China that had been struck by fatal tornadoes in the past three years. The Yancheng tornado affected seven separate towns, from which we randomly chose four towns. The Chifeng tornado affected four villages, fewer than in Yancheng; therefore, we administered the survey to residents from all four villages. Hence, this study conducted a comprehensive survey of these eight areas. Since family members living together shared similar experiences, it was deemed to be more efficient to investigate individuals from different families to gather a more holistic view of the tornado and the related injuries.

Figure 2 shows the flowchart about the sampling process. Two-step sampling was used in the research to avoid sampling bias. A random sampling method was used in both the first step (selecting the families) and the second step (selecting the specific family member). With the help of the Yancheng and Chifeng governments, random sampling was conducted through the household registration system in which every family was given a code [18]. Then, the family member whose birthday was closest to the investigation day was chosen as the participant. Parents completed the survey if the participants were under the age of 18. If the selected participant did not wish to participate for some reason, the individual with the second closest birthday was asked. This sampling method was used until we found a participant from each family. Inclusion criteria included experiencing tornado in Yancheng or Chifeng during the respective tornado disaster, and having their houses destroyed or damaged.

The questionnaire was designed by our research team. (Additional file 1) After modification by disaster emergency medical rescue experts and health service management experts, 10 victims were recruited for pre-testing (these 10 research results are not included in the final analysis). This was done before the formal survey administration in order to avoid a low response rate and unreasonable entry to ensure the quality of the questionnaire. The questionnaire has been widely used in disaster investigations, and has a good validity and reliability [19]. In this study, the Cronbach’s Alpha value is 0.796 for reliability, and the Kaiser-Meyer-Olkin value is 0.619 for validity. Based on other relevant studies that grouped factors of tornado injuries and deaths into demographic characteristics, circumstances, and behaviors [11, 13], the final questionnaire included three categories: first, the demographic characteristics of the victims, including sex, age, marital status, education level, and income level; second, the disaster environment, including being indoors (yes/no), living alone (yes/no), finding refuge (yes/no), the degree of housing collapse, house type, and years in which the house was built; and third, individual behaviors, including disaster avoidance behavior, fear level, and the need for tornado escape drills (yes/no).

The selected research method was a one-on-one questionnaire with the researcher filling out the questionnaire based on the victims’ oral responses. The investigators were master’s degree students in social medicine and public health service management. Unified training for investigators was provided in order to become familiar with the disaster situation and research considerations in advance. A local university volunteer was recruited as a language and culture guide. The survey was entirely anonymous. The interview time for each victim was 15–20 min. Four researchers from the research group traveled to the disaster-stricken area of Yancheng, Jiangsu Province, from July 12 to July 30, 2016, and to the disaster-stricken area in Chifeng, Inner Mongolia Autonomous Region, from August 15 to August 20, 2017.

Tornadoes are amongst the deadliest natural disasters and pose a major threat to worldwide public health. This is the first study to investigate factors associated with tornado injuries in China, which is an important topic to consider for the reduction of casualties. Our findings have some important implications for public health. First, governmental disaster preparedness is very important for community public health in disaster areas. It is necessary to provide reinforcements for the prevention of tornado injuries, especially for high risk groups such as the poor and the elderly. One way to do this would be to improve community shelters and build tornado-safe shelters and basements according to standardized safe building criteria. Second, public health preparedness education should be implemented. The use of disaster prevention programs should be increased, which can help victims to learn coping behaviors while also reducing their fears. Personal and family preparedness planning should be employed, and access to warnings and safe shelters should be enhanced. Third, warning preparedness and hospital plans are critical for community safety. Community tornado warning alarms should be improved, and hospital emergency disaster rescue plans for tornadoes should be standardized to improve rescue effectiveness and efficiency.