““HEAT STRESS, HEALTH AND WELLBEING:HEAT STRESS, HEALTH AND WELLBEING: FINDINGS FROM A LARGE NATIONAL FINDINGS FROM A LARGE NATIONAL

COHORT OF THAI ADULTS”COHORT OF THAI ADULTS”Benjawan Tawatsupa1 ,

Vasoontara Yiengprugsawan2, Tord Kjellstrom3, Sam-ang Seubsman4, Adrian Sleigh2

1Department of Health, MOPH, Thailand2National Centre for Epidemiology and Population Health, ANU, Australia,

3Centre for Global Health Research, Umeå University, Sweden,4Nonthaburi, School of Human Ecology, Sukhothai Thammathirat Open University, Thailand,

Area 5: Social, Environmental and Cultural Issues in Health Promotion26 August 2013

Heat stress in Thailand Tropical developing country: 65 M population

Rapid urbanization: 40% in urban areas (60% in 2030)

High average temperature: 28-30 °C

High relative humidity: 80-90%

Rising temperature By 0.74°C (from 1950 to 2007) (Limjirakan, 2008)

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Annual average of daily maximum temperature 1980-2090Source: SEA START RC, 2009

Objective: To examine the association between heat stress interference with

daily activities and health & well-being

Climate Change

Human exposure

HealthImpacts

Well-beingOverall life satisfaction

HeatStress

Physical health:Energy level

Socioeconomic status & Individual behaviour

(age, sex, marital status, work status, education, income, urban-rural residence, exercise, housework, hours of sleep,

BMI, smoking , and drinking)

Mental Health:Emotional problems

Daily activities: Sleeping Work Daily travel Housework Exercise

Health & wellbeing impacts

MethodsData from a large national Thai Cohort Study (TCS) of distance-

learning open-university adult students aged 15-87 years in 2009 (N=60,569)

Researching the health-risk transition in the Thai population (Sleigh et al, 2008)

Cross-sectional study using multinomial logistic regression analysis and adjusting for a wide array of potential confounders

For each health outcome, we report Odds Ratios (ORs) and 95% confidence intervals

Daily activities and heat interference category

Daily activities

N = 60,569

Heat interference (%)

Not applicable* Never Sometimes Often

Daily travel 3.0 33.7 25.8 37.5Work 14.0 30.3 21.2 34.5Housework 1.3 37.1 31.7 29.9Sleeping 15.7 24.3 32.5 27.4Exercise 0.8 43.1 30.1 25.9*e.g. Use air conditioning

Results

Health and wellbeing outcomes

Overall life satisfaction (score ranged from 0-10) %

9-10 very satisfied (highest) 37.68 (high) 28.86-7 (medium) 21.70-5 not very satisfied (low) 12.0

Energy level %

very much 14.9quite a lot 44.0some 32.0a little or none 9.1

Emotional problems %

not at all 11.3slightly 48.4moderately 25.8quite a lot/extremely 14.5

Daily activities and heat interference category

Adju

sted

Odd

s Ra

tios

Association between heat interference with daily activities and low energy level

Daily activities and heat interference category

Adju

sted

Odd

s Ra

tios

Association between heat interference with daily activities and worse emotional problems

Daily activities and heat interference category

Adju

sted

Odd

s Ra

tios

Association between heat interference with daily activities and low life satisfaction

ResultsNegative health and wellbeing outcomes associated

with increasing frequency of heat stress interfering with daily activities.Worse emotional problems (adj.ORs 1.5 - 4.8)Low energy level (adj.ORs 1.3 - 2.9)Low life satisfaction (adj.ORs 1.1- 2.5)

Adverse health outcomes were when heat stress interfered with Sleeping > daily travel > work > housework > exercise.

Limitations of this study1) Cannot prove that adverse health outcomes occurred at the

same time as the heat stress

2) Difficulties in interpreting causality between heat stress and health outcomes

3) we were not able to make direct measurement of environments or health outcomes - Must classify this study as preliminary in nature- Further studies are needed for more detailed direct observations

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ConclusionsIn tropical Thailand, there already are substantial

heat stress impacts on health and wellbeing

Increasing temperatures from climate change as well as the growing urban population could significantly worsen the situation

Results from this study point to the need for Improved public health surveillance & public awareness

regarding the risks of heat stress in daily life

Thank you• National Centre for Epidemiology

and Population Health, ANU,

Australia

• The Thai Cohort Study team (TCS)

• The ‘High occupational temperature

health and productivity suppression'

programme (Hothaps)

• Department of Health, Ministry of

Public Health, Thailand

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Heat lossCooling by Evaporation

Na+Cl-

H2OH2O

H

Heat gainFrom internal heat source

(Physical activity)

Heat gainFrom external heat source

(Environment)

"Heat stress" (ACGIH, 2008)

Overall heat burden on the body from the combination of:

Body heat generated

Environmental sources Air temperature Humidity Air movement Radiation from the sun or hot

surfaces/sources

Clothing requirements

Background

Motorcyclists were using any shade they could find to get through one of the hottest days in April 2012.

(Ainakul, Bangkok post 21/04/2012)

Heat stress interfered with daily travel

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Why heat stress is interesting:

1) Worldwide interest but insufficient evidence on heat stress & health outcomes in Thailand

2) Heat stress is already a problem in tropical countries

3) Rising temperature may influence the future pattern of deaths or illness

What we know:

1) Increasing temperature in Thailand already occurring (Limjirakan, 2008)

2) The effects of daily heat stress exposure can have a major influence on human daily activities but there is limited information regarding the impact on overall health and wellbeing

What we do not know (research questions):

1) If temperature increases over time, are there any impacts of heat stress on overall health and wellbeing?

Aim: To examine the association between heat stress interference with daily activities and health and wellbeing outcomes

Research questions & Aim of study

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1) Access to a large national cohort (TCS) Represents well the Thai population for geographic location, age,

and socioeconomic status for both sexes

2) Epidemiologic results remained statistically significant When adjusted for a variety of potential explanatory variables

3) Self-reported heat stress was unlikely to be biased Questionnaires included a substantial number of questions on

different exposures and health outcomes Respondents would not be aware of any connection to health

outcomes & would not benefit by over or under reporting

Strengths of this study

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