1 INTRODUCTION Global environmental change and climate change have increasingly impacted onnations in the world It’s estimated that each year climate change contrubutes to 150.000 deaths, million sick people Heart rate and blood pressure (hereinafter called BP) regularly change and are undereffect of various factors including weather, air pollution, activity state, lifestyle, to name but a few The impact of weather is frequently complex with the combination of a series of meteorological elements in close interaction despite of their different natures Meteorological elements have direct impacts and play a role in involving the effects of outside factors onvariations in BP depending on human body’s sensitivity to each outside factor The complexity in the nexus of the aforementioned factors and the variation of heart rate and BP undoubtedly increases in tropical climatic conditions which are characterized by the intensity of weather changes and the great hygrothermal potential of atmospheric processes The People’s Public Security Forceworks in different environmental conditions Road Traffic Police isconstantly exposed to adverse environmental factors Hence, the research topic of "The effects of microclimateson 24-hour heart rate, blood pressure of policemen and Proposed intervention solutions" was carried out under the State-level Project "Research real situation, developing forecasting and control modelsofa number of diseases related to climate change in Viet Nam, ID number DTDL.2012-G/32" The research deals with the followings: Description of changes in 24-hour heart rate and BP in policemen groups in Hanoi City in 2014 - 2015 Analysis of the correlation between selected microclimates factors and 24-hour heart rate and BP of the research subjects Evaluation ofimprovementof the microclimate conditions by equipment set in workplaces of the Road Traffic Police Contributions of the thesis The thesis describes new data on characteristics of variationin 24-hour heart rate and BP of policemen, the correlation between microclimate factors andtheir heart rate and BP and evaluates the effectiveness of microclimate improvement by heat-resistant umbrellas setin workplaces of the Road Traffic Police Moreover, this research providesthe Public Security sector with useful scientific basis in policy making, promulgation ofworking regulationsand mechanismsin order to help policemen in general and the Road Traffic Police with minimizing risks to health from their working environment Structure of the thesis The thesis consists of 115 pages, 14 tables, pictures, 26 figures and 117 references, including 79 foreign language materials There are six main parts with respective lengths as follows: pages of the Introduction, 35 pages of the Literature Review, 16 pages of Research Subjects and Methodology, 39 pages of Research Results, 20 pages of Discussion, and pages of Conclusion and Recommendations 3 Chapter LITERATURE REVIEW 1.1 Microclimates and effects of microclimates on human health: 1.1.3 Effects of climate change on human health: Climate change is projected to have an adverse affect on human health The main direct effects are on accidents, injuries, mental health, thermal shock and so forth while the main indirect effects are on communicable diseases, chronic diseases, malnutrition, maternal and pediatric health, and occupational health 1.1.4 Effects of bad microclimateson human health: 1.1.4.1 Detrimental effects of hot microclimates: Diseases aredoubled inhot microclimate conditionswith common syndromes of heatstroke and convulsions that lead to dizziness, nausea, headache and lumbago In severe cases, human body is stunned with small vessels, shallow breathing, and convulsions due to water and electrolyte imbalance 1.1.4.2 Detrimental effects of cold microclimates: When the body is cold, voluntary muscles and involuntary muscles shrunk along with shivering and goosebumps to produce heat Partial cold causes vasospasm that leads to numbness, itchyand tingling sensation in hands and feet that lead to the reduction of motor ability, loss of sensation, and subsequently result in muscle pain, steroid myopathy, peripheral neuropathy, and so forth Additionally, coldness causes allergy likeasthma, decrease of resistance and immunity, acute respiratory infections, and rheumatism 1.1.4.3 Detrimental effects of heat radiation: Infrared radiationcan cause skin burns and blistery; it goes through the skull, heats up the brain organization and meninges which heatstroke is its direct consequence Ultraviolet radiation is responsible for eye diseases such as vision loss, or skin diseases containing skin burnand skin cancer Laser beams has beenmostly used in industry and scientific research, nevertheless, it results in skin burn and retina burn 1.2 Cyclic variability of heart rate and blood pressure: 1.2.1 Circadian rhythm: In 1964, F Halberg first coined the term "Circadian" with the definitionof“a cycle with a period of about 24 hours that regulates the regular repeats of events roughly at the same hourin any biological process daily” 1.2.2 Variation of heart rate and blood pressure by Circadian rhythm: Frequency of heart rate and BP frequently varies depending on body’s Circadian rhythm, especially in relation to the sleep-wake cycle - At night: Heart is in a resting state and heart rate, BP is going to decrease that reaches the lowest value during sleep is inapproximately between 2:00 AM to 3:00 AM The highest and DBP at night decrease by about 20% lower while sleeping than during daytime, then itraises gradually in the morning - During the day: Heart rate, BP reaches the highest valuesat around 9:00AM to 12:00PM and 17:00PM, and then slightly decreases 1.2.3 Variation of heart rate and blood pressure by ages 1.2.4 Variation of heart rate and blood pressure by body’s posture and movement 1.3 Effects of microclimates on heart rate and blood pressure: 1.3.1 Effects of temperature, humidity, and pressure on heart rate and blood pressure: Previous studies by domestic and international researchers have reported the effects of badmicroclimates on human health Not only workers’ health affected by microclimate in polluted working places, but also the population is suffered from extreme factors such as urban heat island, wave cold phenomenon, heat and humidity, and so forth in their daily living environment 1.3.2 Effects of indoor and outdoor microclimates on heart rate and blood pressure: Studies of Barnett AG indicatethe association between systolic BP and indoor and outdoor temperature from the risk factors surveys from 25 populations in 16 countries The survey results show thata degrees C increase in indoor temperature reduced systolic BPby an average of 0.31 mmHg, and a degrees C increase in outdoor temperature reduced BPby the smaller average of 0.19 mmHg 1.3.3 Variation of heart rate and blood pressure by seasons: Viet Nam is in a tropicalzone It is characterizedby high humidity and a strong monsoons and tropical influences Climate differentiation in different regions occurs due to the complex interrelationship between regional atmospheric circulation and diverse topographies In each region, weather regimeis diverse and relatively complicated with different types of weather, accompanied by sudden changes in weather that lead to increasing the frequencies and levels of variations in heart rate and BP Although some research has been conducted on this issue, there is very little scientific understanding of the aforementioned nexus 1.3.4 Effects of working conditions on heart rate and blood pressure 1.3.5 Other factors having effects on heart rate and blood pressure 1.4 Measurement of 24-hour heart rate, blood pressure and microclimates: 1.4.1 Heat index The actual temperature that human body is affected and felt is not the sameas air temperature, whereas it depends on other factors such as humidity, wind speed, and it is known as Thermesthesia Thermesthesia describes more precisely theeffects of environmental temperature on humans 1.4.2 Measurement of 24-hour heart rate and blood pressure: An automatic Holter blood pressure device records the changes in heart rate and BP over a 24-hour period at regular intervals throughout the day 1.4.3 Measurement of 24-hour microclimates: The application of scientific and technical achievementsin this area is helpful in developing microclimate measuring devices into a diverse, portable, convenient fashion which is applicable in different working conditions and meets dissimilar purposes 1.5 Control measurement of hot microclimates: Including measurements such as properworking organization, workshop and equipmentplanning, ventilation, cooling, equipment and technological processes, personal safety, healthy diet 1.6 Natural characteristics of Hanoi City Chapter RESEARCH SUBJECTS AND METHODOLOGY 2.1 Time frame and location: 2.1.1 Duration: Six years (from October 2013 to June 2019) 2.1.2 Location: Hanoi City 2.2 Research subjects: The research intentionally selected groups of policemen working in different environmental conditions: 2.2.1 Road traffic police (outdoor working group) 2.2.2 Police officers (indoor working group with air conditioner) 2.2.3 Students of Police Academy (indoor working group without air conditioner) 2.2.4 Ambient 24-hour microclimate factors:temperature andhumidity 2.3 Research methodology: 2.3.1 Research design: Research in two stages 2.3.2 Cross-sectional descriptive study (stage 1): 2.3.2.1 Sample size and selection: The calculation of sample size by R software developed by Daniel Ludecke is applied with a coefficient of 0.37, statistical significance of 0.05, power of 0.8, three groups, thus, a minimum size isa population of 231 people We eventually have a selection of 244 participants which is sufficient for the research sample The sample comprises of 61 police officers, 87 police students, and 96 road traffic policemen 2.3.2.2 Information areas to be collected: - 24-hour heart rate and BP of the research subjects - Microclimate factors (temperature, humidity) in 24 hours where subjects are heart rate and BP monitored - Confounding factors to control: + Demographic information: ages, sexes, localities, occupations + Anthropometric information: height, weight + Information on the working conditions and daily life: indoor, outdoor, with air-conditioning, without air-conditioning + Behavioral and lifestyle characteristics: Smoking; intake of alcohol and caffeine, tension, etc 8 + Medical history: cardiovascular disease, diabetes, metabolic disorders, psychosomatic, etc + Personal information at each time of 24-hour BP and microclimate monitoring: activity intensity, clothing, consumption, environmentand health feeling 2.3.2.3 Data collection tools: - 24-hour ambulatory heart rate and BP monitor with the brand of WatchBP O3 (Holter BP) produced by Microlife Switzerland - Mobile 24-hour ambulatory microclimate (temperature, humidity) meter with the brand of RTH20 produced by Extech USA - Questionnaire - 24-hour log 2.3.2.4 Datacollection technique 2.3.3 Intervention research (stage 2): 2.3.3.1 Selection of experimental intervention: Research results in the Stage indicate that Road Traffic Policemen is the most impactedgroup by environmental factors than other ones with noticeable effects of hot microclimate in summer on the variation of the policemen’s heart rate and BP 2.3.3.2 Content of experimental intervention: Testing three types of heat-resistant umbrella (ordinary umbrella, heat-reflective umbrella, and heat-insulation umbrella) at the intersection of Pham Van Dong street and Hoang Quoc Viet street, andthe intersection of Lang Street and Nguyen Chi Thanh Streetduringforecasted hot days (over 350C) in June and July in 2016 The effectiveness of heatresistant umbrellas is evaluated by measuring temperature and humidity under thoseumbrellas At the same time, 36 voluntarily policemenin the test shallscore the heat level of each umbrella type 2.4 Data processing and analysis: The research uses STATA 13 and MLwiN 3.1 for data analysis Moreover, hierarchical multiple regressionis applied in order to identify factors related to the SBP/DBP and heart rate 2.5 Research errors and solutions: The research errors caused bypolicemen’s psychological tension while being Holter monitored, device attachment forgotten, and incomplete 24-hour log will be resolved 2.6 Research ethics: The research is a part of the State-level Project and has been approved by the Ethics Committee in National Biomedical Research of the Ministry of Health and ensures itsstrict compliance with regulations of confidentiality and the rights of research subjects Chapter RESEARCH RESULTS 3.1 General information: The research sample consists of amajority of male (91%), with fairly young average age (26.7 years old) in which the group of between 20-29 years old is the most (54.5%) The percentage of policemen with high blood pressure history is small (1.6%), however, there are a lot of policemen maintaining harmful habits for health with high daily smoking rate (77.5%) and 30.3% of the population having coffee intake every day In addition, policemen are affected by other adverse factors such as working pressure (98%), family issues (99.2%) Notably, 38.1% of those who were interviewed indicate that they are daily under pressure from work while 65.6% of those have irregular pressure from family issues 3.2 Characteristics of 24-hour heart rate and blood pressure variation of policemen 3.2.1 Heart rate and blood pressure vary according to the circadian rhythm (day and night rhythm): 10 Blood Pressure (mmHg) The systolic BP (SBP) changes according to circadian rhythm (day and night rhythm), tends to increase gradually in the early morning (about 5:00AM to 6:00AM), then slightly fluctuates throughout the day, gradually decrease in the evening (about 21:00PM to 23:00PM), and drop at night (about 1:00AM to 4:00AM) This trend is observed in both seasons (summer and winter) BP in summer, SBP value first reaches the peak is earlier thanit does in winter (9:00AM compared to 12:00PM), and tends to decrease significantly earlier than that in winter (21:00PM compared to 22:00PM) with more times that the SBP value are at peak than in winter (4 times compared to times) 125 123 121 119 117 115 113 111 109 107 105 103 101 99 97 95 Summer Winter 101112131415161718192021222324 Time (hour) Figure 3.1: Variation of 24-hour systolic BP of policemen (n=244) Similarly, the diastolic BP (DBP) varies by the circadian rhythm (day and night rhythm), tends to increase gradually in the early morning (about 5:00AM to 6:00AM), then slightly fluctuates throughout the day and gradually decrease in the evening (about 21:00PM), and sharply drop at night (about 1:00AM to 4:00AM) This trend is observed in both seasons (summer and winter) The 11 DBP value in summer is higher than that in the winter at most of the time at night and in the morning, nevertheless, the values in the afternoon and in the evening are not much different The value of DBP during daytime (7:00AM to 18:00PM) is higher than that at night (1:00AM to 6:00AM) In summer, the DBP first reaches its peak earlier than in the winter (8:00AM compared to 12:00PM), it tends to decrease significantly at the same time (21:00PM) in both seasons, the number of peaks in summer is higher than in the winter Blood Pressure (mmHg) as well (3 times compared to times) 80 78 76 74 72 70 68 66 64 62 60 58 56 54 52 50 Summer Winter 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hour) Figure 3.2: Variation of the 24-hour diastolic BP of policemen (n=244) The comparison of characteristics of groups suggest some differences In summer, the SBP value of the Road Traffic Police is higher than that of the Police officers and Police students at most of times during the day (from 8:00AM to 20:00PM) The SBP of the Police officers and Police students first reaches its peak earlier (at about 8:00AM) compared to the Road Traffic Police (at about 9:00AM) The SBP of Road Traffic Police and Police officers tends to decrease at the earlier (21:00PM) than that of the Police students 12 (23:00PM) The DBP value of the Road Traffic Police is higher than that of the Police officers and Police students at most of times during the day (from 9:00AM to 23:00PM) The DBP of the Police officers and Police students first reaches its peak earlier (at about 7:00AM) compared to the Road Traffic Police (at about 11:00AM) The DBP of the Police officers and Police students tends to decrease at the earlier (21:00PM) than that of the Road Traffic Police (23:00PM) The same thing happens in winter when the SBP value of the Road Traffic Police is higher than that of the Police officers and Police students at most of times during the afternoon and night (from 13:00PM to 20:00PM) The SBP of Police students first reaches its peak earlier (7:00AM) compared to the Police officers and Road Traffic Police (at about 11:00AM) The SBP of Road Traffic Police tends to decrease at the earliest (21:00PM) while the SBP of Police officers tends to decrease later (22:00PM), and those of Police students decrease at the latest (23:00PM) The DBP value of Road Traffic Police is higher than that of Police officers and Police students in most of the times in afternoons and evenings (from 11:00PM to 20:00PM) Further more, the DBP of the Police officers and Police students reaches the first peakearlier (7:00AM) compared to that of the Road Traffic Police (at about 11:00AM) The DBP of the Road Traffic Policetens to decrease earlier (21:00PM) compared to that of the Police officers and Police students (22:00PM) The heart rate is in the same way with BP, which tends to vary according to the circadian rhythm (day and night rhythm), gradually increases in the early morning (at around 5:00AM to 6:00AM), then slightly fluctuates throughout the day, it switches to a gradual decline in the evening (at around 19:00PM to 22:00PM) and reaches the lowest value at night (at around 1:00AM to 4:00AM) This trend is observed in both seasons (summer and winter) 13 heart rate (time/mint)) 90 Summer Winter 85 80 75 70 65 60 55 50 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hour) Figure 3.7: Variation of 24-hour heart rate of policemen (n=244) The heart rate between summer and winter is different but not significant In summer, Police students’ heart rate tends to decrease at the earliest (at around 20:00PM), in the meanwhile, the heart rate of the Police officers decreases later (at around 21:00PM), and the Road Traffic Police’s one reduces at the latest (at around 22:00PM) In winter, those of Police students tend to decrease at the earliest (at around 19:00PM), followed by the heart rate of the Police officers and the Road Traffic Police (at around 21:00PM) 3.2.2 Variation of heart rate and blood pressure during sessions of a day: Survey of variation of the SBP during sessions in a day (morning, afternoon, evening, and night), indicates that, daytime SBP (in morning and afternoon) is higher than at night (evening and night) At night, the SBP has the sharpest reduction, forming a BP gap The comparison of the SBP values among the sessions proves thatthere is a biggest difference between the SBP pressurevalue in morning and that in night compared to the other sessions during a day These characteristics are found in both summer and winter 14 Blood Pressure (mmHg) Remarkably, in summer, the night-time SBP does not drop as low as it in the winter Correspondingly, the daytime DBP (morning and afternoon) is higher than that at night (evening and night) Nighttime DBP reaches its trough and creates a BP gap as well 120 118 116 114 112 110 108 106 104 102 100 Summer Evening Night Winter Morning Afternoon Time (session) Blood Pressure (mmHg) Figure 3.10: Average SBP by day sessions of Policemen (n=244) 76 74 72 70 68 66 64 62 60 58 56 54 Summer Evening Night Morning Time (session) Winter Afternoon Figure 3.11: Average DBP by day sessions of Policemen (n=244) Additionally, the comparison of the DBP values among sessions of a day demonstrates similar results with the SBP The DBP values 15 at night and in morning have the largest difference compared to those values in other sessions during a day And these characteristics are found in both summer and winter In summer, the drop of the DBP at night is not as low as it is in winter Road Traffic Police group, there is the biggest difference of the heart rate (time/min) SBP, DBP values between night and morning Summer 86 84 82 80 78 76 74 72 70 68 66 64 62 60 58 56 Evening Night Morning Winter Afternoon Time (session) Figure 3.16: Average heart rate by sessions of Policemen (n=244) The comparison of the heart rate difference between sessions indicates that the heart rate values at night and in the morning have the biggest difference compared to other sessions in a day These features are found in both summer and winter Road Traffic Police group, there is the biggest difference in the heart rate values between night and morning 3.3 The correlation between selected microclimates and 24hour heart rate and blood pressure The correlation between temperature, humidity and heart rate, BP in all research groups has been found that these natural factors have a weak effect on heart rate and BP (the SBP and the DBP) of the Policemen 16 The results of multi-level regression analysis prove that each increased unit in temperature, humidity, or any changes in humidity during the day, or shift from winter to summer, or a comparison between males and females, the SBP shall decrease Even so, any changes of temperature during the day, or any random correlation between temperature and humidity, or any transition of time zones (sessions in the day) compared to the first time zone(1:00AM to 6:00AM), or any increase in supplemented BMI, or increase in any risk point, the SBP shall increase accordingly Similarly, for the DBP, each increased unit in humidity, or shift from winter to summer, or comparison between males and females, the DBP shall decrease Conversely, any conversion of time zones (sessions in the day) compared to the first time zone (1:00AM to 6:00AM), or any additional BMI increase, or increase in any risk point, the DBP shall increase accordingly There are two factors without statistical significance in influencingthe SBPbut affecting the DBP by ages and occupations For the heart rate, only the change of humidity during the day, or the transition of the time zones of the day, or the change of season, ages, occupationsshall statistically contribute towards the increase of the heart rate Interestingly, although the risk points play a significant role in the increase ofthe SBP and the DBP, they have insignificant effect on heart rate In general, the change in ambient temperature or humidity and personal characteristics have an important effect on the variation of Policemen’s heart rate and BP The change in temperature and humidity factors over the period of 24 hours contribute the most to the total change of the SBP and the DBP and heart rate, while personal characteristics contribute the least to the total change of the SBP, the DBP and heart rate (26%, 25%, and 23% respectively) In 17 other words, the temperature and humidity of the environment contribute about 74%, 75% and 77% to the change of the SBP, the DBP and heart rate of the research subjects 3.4 The improvement of microclimate conditionsby equipment set in workplace of Road Traffic Police: Table 3.9: Comparison of heat feeling scoresamong types of sunscreen umbrella of Policemen Comparison pairs Averagescore of heat feeling (n = 36) X SD 7.92 4.97 ± 0.937 ± 0.941 Ordinary and heat-insulation umbrellas: - Ordinary umbrella Heat-insulation umbrella Ordinary and heat-reflection umbrellas: - Ordinary umbrella Heat-reflection umbrella Heat-reflection and heatinsulation umbrellas - Heat-insulation umbrella - Heat-reflection umbrella p