Heat-Related Health Impact and Public Health in Thailand: Gaps and Suggestions

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1 Heat-Related Health Impact and Public Health in Thailand: Gaps and Suggestions Assoc. Prof. Dr. Phongtape Wiwatanadate LL.B., M.D., Ph.D. Department of Community Medicine, Faculty of Medicine Chiang Mai University

2 Definition Heat stress is the net (overall) heat burden on the body from the combination of the body heat generated while working, environmental sources (air temperature, humidity, air movement, radiation from the sun or hot surfaces/sources) and clothing requirements. (ACGIH, 2008).

3 Definition Heat stress is a combination of four aspects of thermal environments which include air temperature, radiant heat, humidity, and air movement. (Parsons, 2003)

4 Definition Heat wave is periods of unusually hot and dry or hot and humid weather that have a subtle onset and cessation, a duration of at least two to three days and a discernible impact on human activities. (WHO, 2015)

5 Physiology of Heat Stress to Human Body Thermoregulatory system Increases in cardiac output and heart rate to deliver blood to the skin surface Producing sweat

6 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss Radiation Convection Conduction Evaporation of sweat

7 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss: Radiation Outward flow of thermal energy or heat loss from an internal heat to the surrounding environment by electromagnetic waves No media is needed.

8 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss: Convection Transfer process of heat from skin surface to environment through movement of surrounding air or water

9 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss: Conduction Process of heat transferring between surfaces of body through direct contact to an adjacent cooler surface

10 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss: Evaporation Cooling process of sweat droplets at skin surface changing state from liquid to gas (water vapor) suspended in air (Parsons, 2003)

11 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss When the air temperature is higher than 35 C, only evaporation of sweat can lower body temperature. (Parsons, 2003).

12 Physiology of Heat Stress to Human Body Physical methods used by humans for heat loss Evaporation of sweat works less effectively when the relative humidity is higher than 80%. (Parsons, 2003).

13 Heat Acclimatisation Physiological ability to tolerate heat after repeating exposure to heat stress (Wyndham et al., 1968)

14 Heat Acclimatisation After being repeatedly exposed to heat, the loss of electrolytes, the blood flow, the heart rate and the body temperature will gradually decrease and become stable. Usually takes about a week. (Parsons, 2003)

15 Heat Acclimatisation Ability for heat acclimatisation is limited by High heat exposure Aging Low fitness Overweight Alcoholism Dehydration Sleep deprivation Existing health problems Using some medications

16 Heat Stress Effects on Health Physical health Mental health Human well-being Occupational health Heat-related deaths

17 Acute Physical Health Chronic

18 Acute Physical Health Effects Heat rash (prickly heat), which occurs when the sweat ducts to the skin become blocked or swell, causing discomfort and itching. Heat cramps, which occur in muscles after exercise because sweating causes the body to lose water, salt, and minerals (electrolytes). Heat edema, which can occur when sitting or standing for a long time in a hot environment. Heat tetany (hyperventilation and heat stress), which is usually caused by short periods of stress in a hot environment.

19 Acute Physical Health Effects Heat syncope (fainting), which occurs from low blood pressure when heat causes the blood vessels to dilate and body fluids move into the legs because of gravity. Heat exhaustion (heat prostration), which generally develops when a person is working or exercising in hot weather and does not drink enough liquids to replace those lost liquids. Heatstroke (sunstroke), which occurs when the body fails to regulate its own temperature and body temperature continues to rise, often to 105 F (40.6 C) or higher. Heatstroke is a medical emergency.

20 Chronic Physical Health Effects Chronic effects on cardiovascular and respiratory systems (Parsons, 2003) Increasing platelet, red blood cell count and plasma viscosity leading to dehydration and hypertension (Wyndham et al., 1968) Hospital admission or deaths with cardiovascular, cerebrovascular and respiratory diseases in many countries Acute or chronic kidney disease due to dehydration (Schrier et al., 1970) Accident and injury due to fainting, confusion, poor concentration, and psychological distress (Hancock, 1981)

21 Mental Health Increase in the number of hospital admissions with dementia, mental and mood disorders during the heat waves (Hansen et al., 2008a) Higher rates of aggressive behavior and suicide (Anderson et al., 2000; Anderson, 2001)

22 Human Well-being Disrupting time spent on personal activities including work, travel, sleep, and leisure time (Kjellstrom, 2009b) by reduced physical and work performance

23 Occupational Health Heavy work in hot environment, especially those with low incomes, such as poor farmers or laborers Severe psychological distress caused by heat exhaustion, such as chronic depression or anxiety disorders (Hansen et al., 2008a) Heat stress has impacts on work capacity and productivity (Hancock and Vasmatzidis, 1998) Heat stress affects well-being of workers by reducing their income and decreasing their life satisfaction (Kjellstrom et al., 2009b)

24 Occupational Health Impacts in Thai Workers Working under heat stress conditions was associated with both worse overall health and psychological distress (Tawatsupa et al., 2010). Workers experienced occupational heat stress were associated with occupational injury (Tawatsupa et al., 2013). There was an association between self-reported occupational heat stress and self-reported doctor diagnosed kidney disease in Thailand (Tawatsupa et al., 2012). Negative health and well-being outcomes (low-energy level, emotional problems and low life satisfaction) associated with increasing frequency of heat stress interfering with daily activities (Tawatsupa et al., 2012)

25 Occupational Health Impacts in Thai Workers Heat-related deaths increased in the hot and wet months compared to the cold months (Tawatsupa et al., 2012). Thai workers in the industrial and agricultural workplaces faced the excessive heat conditions in which heat-related illness were likely to happen (Langkulsen et al., 2010). Those workers who worked under heat stress were likely to have heat symptoms (Jakreng, 2010).

26 Heat-related Deaths A number of studies show that high temperatures during heat waves are associated with marked short-term increases in mortality.

27 (Wikipedia. Heat wave. Effects of Heat Wave European heat wave of 2003 In France, the temperature was above 40 C for 7 days killing 14,802 people. Totally in Europe there were 46,000 deaths. European heat wave in 2007 caused Greek forest fires. In early 2009, South Australia was hit by a heat wave with temperatures reaching 40+ C for six days in a row causing forest fires and killing 210 people.

28 Forest Fires in Greece

29 Forest Fires in Australia

30 Heat-related Deaths Many studies found association between the temperature variation during hot or cold seasons and daily changes in the number of deaths: Myocardial infarction, strokes and pneumonia (Bull and Morton, 1978) Cerebrovascular diseases (Haberman et al., 1981)

31 Risk Factors for Heat Stress Effects on Health and Well-being Individual risk factors: Age: Elderly and Infants Heavy physical activity Insufficient heat protection Existing chronic illness

32 Risk Factors for Heat Stress Effects on Health and Well-being Individual risk factors: Taking medicines: Antidepressants, antipsychotics, and antihistamines reduce the capacity of central nervous system to control body temperature (Bark, 1998; Kaiser et al., 2001; Coris et al., 2004; Kwok and Chan, 2005). Diuretic drugs increase the level of dehydration (Coris et al., 2004). Some medicines (anticholinergic, antipsychotics) can inhibit sweating (Kwok and Chan, 2005).

33 Risk Factors for Heat Stress Effects on Health and Well-being Socioeconomic factors: Poverty Social isolation Housing condition: shading of the building, green spaces, or natural ventilation Air conditioning Urban residents: informal settlements or slums Air pollution: heat stress and air pollution (such as O 3, NO 2, PM 10 ) have synergistic effects on health (Katsouyanni K et al., 1993) Urban climate: urban heat island

34 Urban Heat Island (Heat Island Group:

35 Heat-Related Public Health of Health Sectors in Thailand Research team at Faculty of Public Health, Thammasat University in collaboration with the High Occupational Temperature: Health and Productivity Suppression (HOTHAPS) worked on the climate change and occupational heat stress among Thai workers (Sutthanusorn et al., 2012). Ministry of Public Health has set up the thematic working group to do research and to coordinate the project of health impact assessment from climate change in Thailand (Department of Health, 2009).

36 Heat-Related Public Health of Health Sectors in Thailand Understanding of the heat stress-related health outcomes in relation to climate change has tended to receive less attention. According to the statistics, the diagnosis of heatrelated illness or causes of death from heat stress is under-reported. There are very few published studies investigating the association between heat stress and health impacts in Thailand.

37 Gaps Fewer research on heat-related illness No heat-related surveillance system Heat Health Warning Systems are not well established.