Abstract
The school bus is an important mode of transportation for school-age children, and safety-related issues are always the focus of public concern. Fatal hyperthermia occurring in school buses is an uncommon type of school bus-related injury. An internet search using Chinese internet search engines based on various combinations of keywords including ‘vehicles’, ‘school bus’, ‘children or babies’, ‘hyperthermia or heat stroke’ and ‘death’ was performed. Forty-seven cases of fatal hyperthermia in children which occurred in school buses were retrieved in the study. High ambient temperature, younger age and poor management were identified as risk factors. There is a lack of consensus regarding the legal nature and liability for fatal hyperthermia occurring in school buses. Pre-employment education should be focused on awareness of the dangers of leaving children alone in a school bus. Most importantly, the relevant legislation and regulations on school buses should be implemented. An internal alarm-raising system is recommended to avoid this kind of tragedy.
Introduction
The school bus is an important mode of transportation for children, 1 and safety-related issues are always the focus of public concern. The leading cause of school bus-related fatalities is undoubtedly traffic accidents, while fatal hyperthermia in school buses – which has received far less attention – is a poorly recognised type of school bus-related injury in children. Fatal hyperthermia in school buses has occurred in children who were forgotten or locked in after re-entering a closed school bus over an extended period. Many studies have demonstrated that the temperature inside a parked car exposed to direct sunlight can rapidly reach dangerously high levels. 2 This situation is undoubtedly life-threatening for children trapped inside the car. A survey in the USA showed that approximately 25% of parents reported that they had left a child in their car at some time, which included 14% intentionally left and 11% forgotten. 3 The hyperthermia fatalities of children caused by being left in vehicles were reported in different studies.4–8 In the present study, we collected information from 47 cases of school bus-related fatal hyperthermia in China and analysed the geographic distribution, circumstances and characteristics of the victims. We aimed to raise awareness about these incidents and propose prevention strategies to avoid such tragedies in the future.
Materials and methods
The dataset was based on information obtained from news resources, referring to previous studies.9,10 Various combinations of keywords including ‘vehicles’, ‘school bus’, ‘children or babies’, ‘hyperthermia or heat stroke’ and ‘death’ were searched in internet search engines (including Baidu and Sogou Browser). Each case we selected had a well-documented time and location, as well as pictures of journalist interviews. Moreover, the same case could be found in multiple news media reports in the same period, proving the authenticity of the case. All cases occurred in China. The first identified report was in 2007 and the last in 2019, thus providing a dataset that spanned approximately 12 years. There were few reports about these events before 2007. Although only some reports mentioned a medical or police investigation, it is usually routine management that the cause of death is identified by a physician or forensic pathologist in this kind of case. Fatal hyperthermia in school buses was mainly reported in the provincial and municipal news media outlets. A standardised form was designed to collect data on the date, location, age and sex of the child, circumstance(s) in the school bus (e.g., child forgotten or re-entry), length of time the child stayed in the vehicle before being discovered, meteorological conditions and the individual(s) responsible for each identified case. The exclusion criteria were as follows: (1) Cases where the death was irrelevant to the school bus; (2) cases which lacked explicit geographic and climate information; and (3) duplicated reports.
Results
From 2007 to 2019, a total of 55 cases of paediatric hyperthermia-related deaths in vehicles were reported according to the news sources in China. After the review, 47 cases met the inclusion criteria. The characteristics of the child and the circumstances of being left in the school bus are summarised in Table 1. The majority of the deceased were ≤4 years of age, which is also the school age for day-care in China. There was an approximately equal distribution of males (47%, 22/47) and females (51%, 24/47), and one case with unknown sex. In terms of circumstances, 98% of the children were left in the school bus because they were forgotten by the driver, and 91% of victims were trapped for more than 5 h. In addition, more incidents occurred in rural districts. It should be noted that 17% (8/47) of day-care institutes in the dataset did not have designated school buses for young children, with day-care workers using their private vehicles for pick-up services.
Characteristics and circumstances of 47 fatal hyperthermia in school bus.
The spatial and temporal patterns of fatal hyperthermia in school buses were also investigated. All the incidents occurred in China's eastern and southern regions, with no incidents reported in the western and northern regions. The geographical distribution corresponded to the climate characteristics of China, where the climate is hotter with higher humidity in the eastern and southern regions than in the western and northern regions. According to the news report or the local data published by the meteorological department, maximum daytime temperatures in these cases were collected to characterise meteorological conditions. The findings revealed that the mean daytime temperature was 32±3.5 °C and ranged from 25 °C to 42 °C. Cases of fatal hyperthermia according to temperature are summarised in Figure 1. Remarkably, the number of fatalities was not always associated with increased temperatures. Most fatalities occurred in the temperature range of 30–32 °C (26%, 12/47). Thereafter, the number of cases decreased as the temperature increased. The temporal distribution of fatal hyperthermia in school buses clearly exhibited seasonal variation. Child deaths due to school bus-related hyperthermia occurred mostly between April and October, with the highest number of cases in July (Figure 2). No such fatalities were reported during the winter months. However, the distribution of such cases did not reveal any clear differences according to year.
The cases of fatal hyperthermia in different temperatures.
Incidents of hyperthermia death of children in school bus in different months.
Discussion
With global warming contributing to the increased frequency and severity of heat waves, hyperthermia has become a new threat to human health. Hyperthermia is a kind of heat-induced illness that occurs when an individual's core body temperature is elevated beyond the normal range because the person's body produces or absorbs more heat than it dissipates, eventually leading to dehydration and multiple organ failure. Clinical diagnosis is predominantly based on symptom presentation, an abnormally high body temperature of the patient, high temperature environment exposure, routine physical exams and laboratory tests. Although some autopsy findings such as visceral congestion, diffuse petechiae and haemorrhages of serosal membrane were observed in fatal hyperthermia,11–13 the pathognomonic histological feature was absent at post-mortem. To avoid overestimating or underestimating the number of heat-related deaths during the heat wave of 1995 in Chicago, the Medical Examiner's Office in Cook County proposed the criteria for heat-related death which majorly included a core body of 40.6 °C, environmental or circumstantial evidence and heat wave condition. 14
Our study identified several distinct characteristics of fatal hyperthermia in school buses. First, these events occurred under specific meteorological conditions. We found that the ambient temperature in fatal hyperthermia cases was 32 ± 7 °C, which was similar to a previous study that reported a temperature range of 32 ± 5 °C. 15 Deaths from fatal hyperthermia were increased between 26 and 32 °C, and then decreased from 32 to 40 °C. McLaren et al. 16 showed that the internal temperature of a vehicle can reach 47 °C within 60 min in direct sunlight when the ambient temperature is 22 °C. Thus, it is still dangerous to leave a child in a relatively non-high temperature due to the rapid heating of closed vehicles. High internal temperatures and poor ventilation in school buses influence heat dissipation of the human body. It is generally recognised that the children died of multiple organ failure induced by high temperatures. 17
Second, fatal hyperthermia in school buses usually occurs in children <5 years of age. Children at this age are still dependent on adult care because their cognitive ability and physical constitution are very immature. When trapped in a school bus, they are neither aware of the danger nor able to exit an enclosed school bus without help. Our study revealed that 91% of victims were trapped in a school bus for >5 h, while a previous study reported that a young child left in a closed vehicle could die within 2 to 4 h if undiscovered. 18 The factors that make the children more prone to hyperthermia than adults are attributed to their underdeveloped thermoregulatory system which is less efficient at regulating body temperature, the high surface area to mass ratio which increases transepidermal water loss and immature sweat glands which affects their ability to dissipate heat effectively. Finally, all these factors make the children vulnerable to high temperatures and more likely to develop fatal hyperthermia in enclosed school buses. 19
Third, our study revealed that fatal hyperthermia in school buses is more likely to occur in rural areas, which accounted for nearly two-thirds of all reported cases. The socioeconomic basis of this phenomenon is worth exploring. With the development of urbanisation in China, an increasing number of adults have moved to urban centres, and voids have appeared in rural districts. During this process, many rural schools have been closed or consolidated. From 2001 to 2010, the total number of rural schools decreased by 50%. 20 This meant that children had to travel further to go to school, and school buses became increasingly necessary. However, due to the lack of timely relevant legislation and regulations, there were many problems with transportation for the students. From 2010 to 2011, school bus-related accidents led to >60 child deaths and 146 injuries. 21 In rural districts, governmental financial support for day-care centres was limited. Some day-care centres ignored safety rules for school buses due to limited budgets. In our dataset, some day-care workers used their private vehicles – rather than a designated school bus – to transport students. A large security risk may result from such substandard management. Our study identified 30 fatalities that occurred in rural districts, which accounted for 64% of all cases. Moreover, considering the selected prejudice among news media outlets, the actual incidence of these tragedies may be underestimated.
Fatal hyperthermia in school buses usually involved complicated judicial issues. The adjudication of legal responsibility is controversial in such cases. According to news reports and China Judgements Online, the day-care workers and bus drivers in every case were taken into custody, and the day-care centres involved were suspended immediately after the victims were found. Among these cases, only two cases received further reports about judicial outcomes, while the verdict of the other cases remains unknown. In the first case, the driver was charged with gross negligence and involuntary manslaughter and was ultimately sentenced to jail for 18 months. At the same time, the victims’ families obtained civil compensation from the day-care centre. However, in the second case, the day-care centre and the victims’ families reached an out-of-court settlement, and no one was sentenced to jail. In addition, the responsibility of the Education Bureau for managing day-care centres was not reported. Diamond 22 also reported one lethal hyperthermia case where the mother unintentionally left her nine-month-old baby boy in a car. The mother had been prosecuted for felony child neglect and second-degree murder initially, then reduced to involuntary manslaughter, and found not guilty ultimately. Diamond thought that the loss of awareness of a child in a car is due to a failure of prospective memory. The different judicial outcomes of these cases revealed a lack of consensus regarding the legal nature of and liability for fatal hyperthermia occurring in vehicles.
Prevention of these tragedies requires the appreciation and effort of society. There are a series of measures on childcare that need to be improved. First, relevant legislation and regulations on school buses should be perfected to enhance safety, such as standardised school buses. Currently, the manufacturing requirements for school buses in China are based on the 2012 standards in which only several technical standards such as bus structure, power, safety belts, child seats and etc. are involved. 23 No standards have been put in place to guarantee the safety of all the children under guardianship in this kind of situation, such as two caretakers provided for each school bus. Thus, national legislation is urgently needed. Second, it is important to improve the qualification requirements of the professional staff in day-care centres. The service staff should receive professional pre-service training and be fully aware of the danger of leaving a child unattended in all types of environments, including the school bus. Third, internal warning devices in school buses are helpful that can send an alert message to the driver in time when detecting young children left in the school bus. Such devices have already been used in private vehicles to alert parents when they forget their child. 24
Conclusion
Forty-seven cases of fatal hyperthermia occurring in school buses between 2007 and 2019 were reported. High ambient temperatures, younger age, lack of awareness of danger and poor management were risk factors for this type of accident. To date, there is a lack of consensus regarding the legal nature and the liability for fatal hyperthermia occurring in school buses. The focus should be on the awareness of the dangers of leaving children unattended in school buses and the installation of warning devices. Most importantly, relevant legislation and regulations on school buses should also be promptly enhanced. Finally, we also hope to raise awareness of this under-recognised risk especially in countries which are less equipped to handle hot weather.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Natural Science Foundation of China (grant number 82072117).
