Summary of PhD thesis in Medicine: The effects of microclimateson 24-hour heart rate, blood pressure of policemen and Proposed intervention solutions

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.

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, 5 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:

1 Description of changes in 24-hour heart rate and BP in policemen groups in Hanoi City in 2014 - 2015

2 Analysis of the correlation between selected microclimates factors and 24-hour heart rate and BP of the research subjects

3 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, 4 pictures, 26 figures and 117 references, including 79 foreign language materials There are six main parts with respective lengths as follows: 3 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 2 pages of Conclusion and Recommendations

Chapter 1 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 1 degrees C increase in indoor temperature reduced systolic BPby an average of 0.31 mmHg, and a 1 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 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:

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

+ 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 350C) 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

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):

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

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

(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)