The effects of microclimateson 24 - Hour heart rate, blood pressure of policemen and Proposed intervention solutions

e 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 6 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 2 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: 7 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 1 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 35 0 C) in June and July in 2016. The effectiveness of heat- resistant 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 9 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 3 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 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 3 times). 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 95 97 99 101 103 105 107 109 111 113 115 117 119 121 123 125 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 B lo o d P re ss u re (m m H g) Time (hour) Summer Winter 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 as well (3 times compared to 2 times). 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 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 B lo o d P re ss u re (m m H g) Time (hour) Summer Winter 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 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 4 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. 50 55 60 65 70 75 80 85 90 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 h e ar t ra te (t im e /m in t) ) Time (hour) Summer Winter 14 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). Night- time DBP reaches its trough and creates a BP gap as well. Figure 3.10: Average SBP by day sessions of Policemen (n=244) 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 100 102 104 106 108 110 112 114 116 118 120 Evening Night Morning Afternoon B lo o d P re ss u re (m m H g) Time (session) Summer Winter 54 56 58 60 62 64 66 68 70 72 74 76 Evening Night Morning Afternoon B lo o d P re ss u re ( m m H g) Time (session) Summer Winter 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 SBP, DBP values between night and morning. 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 24- hour heart rate and blood pressure The correlation between temperature, humidity and heart rate, BP in all 3 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. 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 Evening Night Morning Afternoon h ea rt r at e (t im e/ m in ) Time (session) Summer Winter 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 3 types of sunscreen umbrella of Policemen Comparison pairs Averagescore of heat feeling (n = 36) X SD p Ordinary and heat-insulation umbrellas: <0.0001 - Ordinary umbrella 7.92 ± 0.937 - Heat-insulation umbrella 4.97 ± 0.941 Ordinary and heat-reflection umbrellas: <0.0001 - Ordinary umbrella 7.92 ± 0.937 - Heat-reflection umbrella 3.19 ±1.091 Heat-reflection and heat- insulation umbrellas <0.0001 - Heat-insulation umbrella 4.97 ± 0.941 - Heat-reflection umbrella 3.19 ±1.091 Interview results of 36 voluntary policemen with the content of cores on heat feeling when standing under three types of umbrellas, with a scale from 1 (corresponding to a Very pleasant feeling) to 10 (corresponding to a Very uncomfortable feeling) demonstrates that, with heat-insulation umbrellas, Road Traffic Police feel more pleasant (4.97 points) than ordinary ones (7.92 points), this difference is statistically significant (p <0.0001). Similarly, when comparing the heat feeling scale for ordinary and heat-relative 18 umbrellas, it is also shown that, the Road Traffic Police feel more comfortable (3.19 points) with the heat-relative umbrellas than the ordinary ones (7.92 points), this difference is statistically significant (p<0.0001). Comparison results of heat feeling between heat- insulation and Heat-reflection umbrella found that, the Road Traffic Police feel more comfortable (3.19 points) with the heat-relative umbrellas than the heat-insulation ones (4.97 points), this difference is statistically significant (p <0.0001). Table 3.10: Comparison of temperatures among three types of sun protection umbrellas Comparison pairs Average temperature ( 0 C) (n = 6619) X SD P Ordinary and heat-insulation umbrellas: <0.0001 - Ordinary umbrella 35.71 ± 5.30 - Heat-insulation umbrella 34.08 ± 4.18 Ordinary and Heat-reflection umbrellas: - Ordinary umbrella 35.71 ± 5.30 <0.0001 - Heat-reflection umbrella 34.22 ± 4.25 Heat-reflection and heat- insulation umbrellas <0.0001 - Heat-insulation umbrella 34.08 ± 4.18 - Heat-reflection umbrella 34.22 ± 4.25 Comparison of the average temperatures of the sun protection umbrellas indicates a significant difference, the temperature in the heat-insulation umbrella (34.08 0 C) is lower than the temperature in the ordinary umbrella (35.71 0 C) which has statistical significance (p <0.0001), the temperature in the Heat-reflection umbrella (34.22 0 C) 19 is also lower compared to the temperature in the ordinary umbrella (35.71 0 C) which gains a statistical significance (p <0.0001) but higher than the temperature in the heat-insulation umbrella (34.08 0 C) which is statistically significant (p <0.0001). CHAPTER 4 DISCUSSIONS 4.1. Characteristics of variation in 24-hour heart rate and blood pressure of policemen 4.1.1. Policemen’s heart rate and blood pressure varies by 24- hour circadian rhythm The data suggests that there is a common trend in which heart rate and BP gradually increases in the morning (between 5:00AM and 6:00AM), reaches the first peak at about 8:00AM to 12:00PM, then it slightly fluctuates throughout the day and gradually decreases in the evening (about 21:00PM to 23:00PM), and reaches the trough at night (about 1:00AM to 4:00AM). This finding is similar to a number of previous studies describing the BP decrease at night with the lowest at about 2:00AM to 3:00AM, and increase in the morning, at about 9:00AM to 12:00PM and 17:00PM when BP increases and then slightly drops). Nguyen Huu Tram Em et al. pointed out the line graph regarding two BP peaks during the day from 7:00AM to 9:00AM and from 6:00PM to 8:00PM. In addition to that, in her study, she identifies a trough in the period of 1:00AM to 3:00AM and BP start to increase at 5:00AM to 6:00AM. Although the trends of heart rate and BP are similar, each policemen group has their respective characteristics as well as the differences between the highest BP and the lowest BP. The Police officers’ highest BP reaches their first peak at about 8:00AM to 11:00AM, in the meanwhile, Police students’ one is at about 7:00AM to 8:00AM, and Road Traffic Police’s first peak is at about 9:00AM to 11:00AM. The Police Officers’ lowest BP decreases at about 21:00PM to 22:00PM while Police students’ one is at 23:00PM and 20 Road Traffic Police is at 21:00PM. The point of time when the Police Officers’ highest BP goes down is at about 21:00PM to 22:00PM whilst Police Students’ one is at about 23:00PM and Road Traffic Police’s is at 21:00PM. Correspondingly, for the lowest BP, it is 22:00PM for Police Officers and Police Students, and at 21:00PM to 23:00PM for Road Traffic Police. It is obviously shown that the Road traffic police reach their peak at the later time compared to those oftwo other groups, however, there is insignificant difference among points of time for BP to decrease. This shall be explained in the following part. In this study, data on difference of heart rate and BP points out that the average difference is biggest between night and morning in comparison to differences among other sessions during a day. In other words, when night shifts to morning, heart rate and BP has a sudden increase (sharp raise) compared to the BP variation in other sessions by day. It is described by many relevant researches that hypertension goes up in the morning shall adversely lead to stroke. BP sharply raises in early morning, including diastolic and systolic BP, forfirst hours is a change pattern related to a poor prognosis. The Road Traffic Police in this study have the BP sharp raise in the morning compared to the rest. It is suggested that this group is more likely to have cardiovascular events than other groups. This issue shall be discussed in the part regarding impacts of work environment on cardiovascular risks. 4.1.2. Variation of 24-hour heart rate and blood pressure by seasons: Based on the analysis of heart rate and BP variation by seasons in this research, it is indicated that the highest BP in summer reaches its peak earlier than that in winter (except the Police Students with insignificant difference between 8:00AM and 7:00AM) and BP values at peak more times than they are in winter. Remarkably, BP in summer is higher than it is in winter at most of the times during a 21 day. Nevertheless, it is not obviously different when observing heart rate of Police Students and Road Traffic Police. On the contrary, for Police Officers’ heart rate in summer is lower than it is in winter with insignificance. The results obtained from this research are unlike what J. Goodwin et al. discussed earlier, showing that the 24- hour BP in elderly groupsin winter was higher than it is in summer compared to young people. The explanation for this difference is that in the UK, where the research of J. Goodwin et al. was carried out, the weather was pleasant in summer with temperature ranges between 18 to 20 0 C, while the winter was chilly with temperature ranges between 6 to 7 0