A Cross-Sectional Study of Heat-Related Knowledge, Attitude, and Practice among Naval Personnel in China

Background: Heat-related illnesses have signicant impacts on health, and military personnel were widely exposed to risk factors of heat-related illness. Knowledge, attitudes and practices (KAP) are the three of the most important factors to prevent the heat-related illness. A cross-sectional study was designed to explore heat-related KAP of military personnel in China. Methods: This survey was conducted in June 2019. A total of 646 military personnel were recruited from 2 navy troops in tropical zone and one in temperate zone. Data regarding demographic characteristics and KAP scores were collected using questionnaires. Univariate analysis and Scheffe's method were used for data analysis. Results: The mean K-score was relatively high (10.37, SD=1.63), but the subscore of awareness of exertional heatstroke and the risk of alcohol and soda drinks were inadequate. There are noticeable differences in the mean K-score according to age, military ranks and education levels(P<0.05). The mean A-score was 7.76(SD=2.65). The participants from tropical zone or had relevant experience had higher A-score (P<0.05). The mean P-score was 3.80 (SD=1.12), and participants from temperate zone had higher P-score (P<0.001). Conclusions: Military personnel's awareness of the prevention and rst-aid measures of heat related illnesses need to be strengthened, and it is very important to develop educational programs and enrich systematic educational resources of heat-related illness.


Background
The Intergovernmental Panel on Climate Change (IPCC) projects that the frequency, duration and intensity of extreme weather may increase in the coming decades [1]. The extreme weather of exceed 3consecutive-day with maximum temperature over 35 °C could be described as heat wave [2]. The frequency of heat waves has increased in most parts of Asia [3], Europe and Australia. Furthermore, episodes of heat waves can have signi cant impacts on health and present a challenge for occupational health protection. Heat-related illness includes heat stroke, heat exhaustion, rhabdomyolysis, heat spasm, heat syncope and heat rash. The inverse effects of heat-related illnesses on mortality have been widely reported. Mortality from heatstroke among the elderly exceeds 50% [4]. Another study, conducted in 66 cities in China, showed that 5.0% of excess deaths may be associated with heat waves [5]. The global estimate for the number of heat-related deaths will increase by about 90,000 annually in 2030 and more than 255,000 in 2050 [6]. Therefore, more attention should be paid to the insidious health effects of heatrelated illness.
Risk factors associated with heat-related illness may be environmental or individual. As exogenous factors, environmental risk factors may include high temperature, humidity, direct sun exposure, etc. The individual risk factors, also known as endogenous factors, may include insu cient uid intake, physical exertion, physical condition, medications, pregnancy, etc [7]. Military personnel, especially those in low latitude area where soldiers routinely pay high levels of physical exertion in high ambient temperature and humidity environment, are widely exposed to both exogenous and endogenous risk factors of heatrelated illness. Military endeavors in heat waves can alter the judgment and physical performance of military personnel, and end with signi cant impairment of individual's ability to work, or even lead to death [8,9]. Therefore, reducing heat-related illness is one of the key factors to ensure the combat effectiveness of the army in heat waves condition.
The Knowledge, Attitudes and Practice (KAP) study among speci c populations is to collect data on people's knowledge, perception and behaviors about a certain topic. literatures showed that knowledge of heat waves, attitudes to risk factors and adaptation practices are the three of the most important factors to prevent the heat-related illness [10]. KAP studies on heat waves has been mostly performed in different occupations. For instance, a KAP study about health professionals in Victoria found that an opportunistic, reactive approach in conjunction with gaps in knowledge leave the aged at risk of preventable harm from extreme hot weather [11]. For military personnel, only a few studies have focused on the knowledge of heat related illnesses among Chinese soldiers, but there is a lack of investigation and correlation analysis on the three aspects of knowledge, attitude and practice. Therefore, in this study, three troops with different risk factors in low latitudes were selected to explore heat-related KAP of military personnel in Chinese Navy for the rst time, which aimed to provide data for future policy formulation and implementation in response to heat waves and associated adverse impacts.

Climate Zone of Study Area
A total of 3 navy troops took part in the study. Two of the sampled troops are located in the tropical zone (geographic coordinates, approximately 9° north latitudes), under high temperature and humidity stress the whole year. The annual mean temperature is 28-30℃, while the highest surface temperature is up to 60℃ in summer. The precipitation and summer sunshine hours are 1200-3300mm and 6.03h. The other sampled troop is situated in a warm temperate continental monsoon climate zone (geographic coordinates, approximately 30° north latitudes), characterized by solar-rich sunshine (6.4h in average), with an annual mean temperature of 8.8℃ and the precipitation of 428.8mm. There are about 18 days per year called "heat day", in which the maximum temperature exceeds 35℃ [2].

Study Participants
The convenience sampling method was utilized to selected military personal from 3 navy troops. The target population of this study was active-duty Navy members without health care work experience. A platoon is a military units containing 30-50 Navy members. A total of 15 platoons of troops in the tropical zone were included in the study, with 560 navy members participated in the study. In the temperate zone, three platoons were included in the study with totally 86 navy members.

Design and Data Collection
A questionnaire was developed based on a literature review on heat waves and heat-related illness. The questionnaire consisted of four sections: (1) socio-demographic information, including age, year of military service, education level, marital status, military ranks and heat-related illness experience; (2) Knowledge section: 18 questions on knowledge about heat-related illnesses (13 true-false items and 5 multiple-choice items), including symptoms and treatment about heat-related illness and risk factors of heat waves. (3) Attitude section: 4 attitude-related questions, i.e., whether measures were taken by navy members to prevent heat-related illnesses in heat waves. (4) Practice section: 6 questions on practices for preventing heat-related illnesses.
Data were collected in June 2019. Participant were interviewed by well-trained researchers using the structured questionnaires. Various actions were taken to ensure the quality of the questionnaire. Firstly, a panel of experts were consulted at the questionnaire development stage, and then a small scare of pilot study was performed to do semantic analysis. Before the survey, all the researchers were trained systematically to be familiar with the uni ed guide language and lling methods. All questionnaires were lled in and collected on the spot to increase the return rate. Two independent researchers performed data collation and entry to minimize errors in the data processing.

Statistical Analysis
There were eighteen, four, and six items in knowledge (K), attitude (A), and practice (P) section respectively. For K section, the true-false items and multiple-choice questions were assessed by assigning 1 point to correct answer, or otherwise 0. In the multiple-choice questions, however, if a wrong option was ticked, it counted as 0. In A section, a 4-point scale that was used as the marking scheme (the options were arranged from 1-4 with no higher or lower score). For P section, scores were assessed by assigning 1 point to each response of "Yes" and 0 point to response of "No." The score ranges for the K, A, and P sections were 0-18, 1-16, and 0-6, respectively.
The SPSS for Mac version 25.0 program was used for data analysis. Mean and standard deviation (SD) values were calculated for continuous variables. Categorical variables were computed as a percentage of subjects with the perspective attribute. Univariate analysis of variance was used to test the association of each demographic characteristic with the K, A, and P-scores and the overall score. Scheffe's method was used in further paired comparisons if necessary. Pearson correlation analysis was performed to clarify the correlations among the K, A, and P scores. p < 0.05 was considered statistically signi cant.

Ethical Statement
The study was approved by the ethics committee of the institutional review board of the Naval Medical University. Written informed consent was obtained from all participants before the survey. All the data obtained was anonymous.

Participant Demographic
In the baseline survey, a total of 646 subjects were approached and invited to join this study, but 6 participants did not complete the questionnaires, leaving 640 (99.1%) in the nal analysis. The socialdemographic characteristics of the participants is presented in

Responses to Questions on Attitude and Practice
In the Attitude section, the ratio of the participants who selected very concern about the risk of heatrelated illnesses was only 26.2%. 40.4% of the participants considered they were somewhat sensitive for heat-related illnesses, while less than 12.8% answered "Not at all". In respect of the Practice section, most of the participants (79.7%) reported that their leaders generally arranged outdoor activities at relative cooler time and the medics took intervention measures (74.4%) when a high temperature warning is released. Additionally, 71.9% of the participants were aware of that it is necessary to implement good heat-related illnesses preventive measures. However, only 64.8% of participants received health education before eld training, and nearly three-fourth of the participants (74.4%) stated that they drank water only when thirsty (Table 3).

Mean Score of Knowledge, Attitude and Practice
The detailed mean KAP score and mean overall score according to the demographic characteristics were showed in Figure 1. The mean K-score was 10.37(range 3-13, SD = 1.63). There are noticeable differences in the mean K-score according to age, military ranks and education levels(P<0.05). The paired comparisons using Scheffe's method indicated that mean K-score was lower in the participants younger than 20 years old compared with the other age groups (P<0.05), and was higher among junior o cers(P<0.05) and those had bachelor or above degree(P<0.05).

Correlation among Knowledge, Attitude and Practice
Correlation analyses suggested a signi cant positive correlation between A and P scores (r = 0.170, P<0.001), however, the correlations were weak. A positive correlation was found neither between K and A score nor K and P score (Table 4)..

Discussion
Several studies have reported that heat waves have adverse effects on human health [12]. People's awareness to risk, protective practices and knowledge about of heat-related illness are crucial elements for reducing harmful effects of heat waves [2]. However, to our knowledge, this is the rst study to survey the military personnel's KAP with regard to heat-related illnesses in Chinese Navy. Study on this eld may be great signi cant as military personnel were widely exposed to risk factors of heat-related illness. Therefore, the nding of this study may provide essential references for military training and health education to military personnel.
In this survey, the majority of the participants had high score on most K-questions and had well awareness and protective practice towards heat-related diseases. However, some subgroups showed lower K, A, P scores, which were related to demographic factors, environmental difference and personal experience.
Knowledge plays an important role to mitigate the adverse effects of heat waves [13]. By analyzing participants' answers to K-questions in this study, we nd that military personnel had high score on most common-sense questions about heat-related illness, such as 95% of the participants knew that cool environment, drink uids, apply cool water, ice packs and fanning were interventional measures for heatrelated illness. However, the rates of correct answers for exertional heatstroke were extremely low. Only 37.5% of the participants recognized the severity of exertional heatstroke and 25.2% of the participants identi ed no sweating as danger signal. Exertional heatstroke is a medical emergency, which is directly related to intense physical activity. Military personnel under conditions of exercise intensity and environmental exposure is vulnerable to exertional heatstroke [14]. An epidemiological survey on military personnel showed steady increase in morbidity and mortality of exertional heatstroke in the past decade [15], but effective recognition and promptly treatment can greatly reduce its mortality rate [16]. Therefore, it is necessary to strengthen military personnel's awareness of the prevention and rst-aid measures of exertional heatstroke.
It is stunning to note that 85% of the participants chosen soda drink for the heat victim, and 93.4% of them believed that alcohol beverages were bene cial for preventing one from heat-related illnesses during eld training. The misinformation that alcoholic beverages and soda drinks contributing to the prevention and treatment of heat-related diseases may be related to the media channel. Military personnel may access information through television, internet and smart phone [17]. However, the information from these media usually has commercial purposes, which may be misleading to the audience. For example, advertisements often link ice beer to the hot summer, and show the image of a sportsman in high ambient temperature drinks ice soda drink delightedly. The erroneous information may be fatal at the critical moments of rescuing severe exertional heatstroke. According to a literature report from New England Journal of Medicine, alcohol heightens the metabolic response to physical activity and is the risk factor for exertional heatstroke [4]. Therefore, administrators of the army should pay efforts to develop educational programs to improve the military personnel's knowledge with regard to heat-related illness, moreover, governments and relative institutions should call on the dissemination of relevant knowledge on mass media.
Through the analysis of demographic characteristics, we nd that participants younger than 20 had lower K-score(p<0.05). This result was in contrast to the ndings of Jing Li et al [2]. The reason may be that the age span of objects in Jing Li's study was large, ranging from 15-91, whereas the military personnel involved in our study were all young with the mean age of 25.1 years old. Additionally, K-score was higher among junior o cers(p<0.05) with higher educational levels, which was similar to those of previous studies [18]. This results suggest that we should carry out health education on heat-related illness especially for young soldiers. Simultaneously, the advantage of military o cers with high education level and good mastery of relevant knowledge should be taken, and they could be further developed to be instructors in health education projects.
The majority of the participants had well awareness towards heat-related diseases. 87.5% of the participants intended to take preventive measures in high ambient temperature, and 75.1% of the participants considered themselves sensitive for heat waves. Moreover, participants from a humid tropical zone had a higher mean A-score than those from temperate zone. However, with regarded to the risks of heat-related illnesses, participants expressed opposite attitudes. Most of them (44.5%) reported only little concern about the risks, which is probably due to insu cient knowledge of the risks of heatrelated illness [19]. Hence, it is very important to enrich systematic educational resources to promoting such information.
The Pearson correlation analysis indicated that there is weak correlations between A and P score, consistent with the results of previous studies[20], in which the authors reported that risks awareness and adaptation practices were positively correlated. The explanation as to this correlation could be provided by the Health Belief Model. This model asserts that health-related practices are determined by whether people recognized the seriousness of the problem and perceived themselves to be susceptible to heatrelated illness [21]. Therefore, a positive attitude or well awareness towards heat-related diseases will promote preventive practices, which would reduce the adverse effects of heat waves. But a subgroup in this study showed an interesting result that military personnel worked in tropical zone had positive awareness, but low P-score. These nding may be partially explained by three factors. Firstly, people in low latitudes are better adapt to heat through behavioral and structural adjustment than people in high latitudes, which called thermal acclimatization [22]. Therefore, although positive attitude toward heatrelated illness, military personnel in tropical zone had limited protective behaviors. Second, the majority of military personnel were young man who may be more willing to take risk and believe that they can handle heat. In addition, motivation and pressure from peers and instructors are likely to drive the young to perform beyond their physiological capability, which is also one of the major risk factors for exertional heatstroke [23]. It shows that many factors might in uence people's behavior, so further studies are needed to explore the production of protective behaviors.

Limitation
There are several limitations in our research. Firstly, our present study only investigated KAP of heat related illnesses in Chinese naval o cers and soldiers, thus, caution should be applied when the results were generalized to other military services. Secondly, most of the participants came from the tropics and only a small sample were from the temperate zone, which devalued the representativeness of the study results. Thirdly, the questions in the questionnaires relating to KAP of heat related illnesses are limited and not comprehensive and detailed enough, which may not explore the knowledge mastery, behaviors and attitudes in depth.

Conclusion
Our research revealed that participants had high score on most common-sense questions and had well awareness and protective practice towards heat-related illness. However, the risk of exertional heatstroke and alcohol and soda drinks were inadequate. In addition, some subgroups showed lower K, A, P scores, which were related to demographic factors, environmental difference and personal experience. Thus, military personnel's awareness of the prevention and rst-aid measures of heat related illnesses need to be strengthened. In order to address these issues, it is very important to develop educational programs and enrich systematic educational resources of heat-related illness.

Abbreviations
The Intergovernmental Panel on Climate Change (IPCC); The Knowledge, Attitudes and Practice (KAP); Standard Deviation (SD).

Declarations
Ethics approval and consent to participate: The study was approved by the ethics committee of the institutional review board of the Naval Medical University. Written informed consent was obtained from all participants before the survey. All the data obtained was anonymous.

Consent for publication
This manuscript does not contain any individual person's data. All participants were informed of the publication of research ndings through information sheets. Permission to publish the results from this study was granted by the ethics committee of the institutional review board of the Naval Medical University.
Availability of data and materials: Data is not available for online access, only members of the research team have access to the data.
Competing Interests: The authors declare that they have no competing interests.
Funding: This study was supported by Shanghai Municipal Education research projects (C17008).
Author Contributions: LG and SX conceived and designed the study, and administrative support; XW undertook data analysis, results interpretation and manuscript preparation; DX organized the eld works and collected the data; YW was responsible for critical revision of the manuscript.  Table 2. Responses to knowledge items (n=640).

Figure 1
Detailed mean KAP score and mean overall score according to the demographic characteristics