BackgroundGlobal climate change is already increasing the average temperature and direct heat exposure in many places around the world.ObjectivesTo assess the potential impact on occupational health and work capacity for people exposed at work to increasing heat due to climate change.DesignA brief review of basic thermal physiology mechanisms, occupational heat exposure guidelines and heat exposure changes in selected cities.ResultsIn countries with very hot seasons, workers are already affected by working environments hotter than that with which human physiological mechanisms can cope. To protect workers from excessive heat, a number of heat exposure indices have been developed. One that is commonly used in occupational health is the Wet Bulb Globe Temperature (WBGT). We use WBGT to illustrate assessing the proportion of a working hour during which a worker can sustain work and the proportion of that same working hour that (s)he needs to rest to cool the body down and maintain core body temperature below 38°C. Using this proportion a ‘work capacity’ estimate was calculated for selected heat exposure levels and work intensity levels. The work capacity rapidly reduces as the WBGT exceeds 26–30°C and this can be used to estimate the impact of increasing heat exposure as a result of climate change in tropical countries.ConclusionsOne result of climate change is a reduced work capacity in heat-exposed jobs and greater difficulty in achieving economic and social development in the countries affected by this somewhat neglected impact of climate change.

This paper presents the spatial differentiation to biothermal conditions in the Ziemia Kłodzka region of Poland, the basis for the assessment being the Universal Thermal Climate Index (UTCI), with spatial analysis relating to maps made using a GIS application. The differentiation to UTCI values was defined for several types of weather.The greatest spatial differentiation to values for heat stress is to be observed in sunny, hot and dry weather in the presence of only gentle winds. Forests stand out from other types of landscape in the way they mitigate heat loads significantly.

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It is accepted that the earth's climate is changing in an accelerating pace, with already documented implications for human health and the environment. This literature review provides an overview of existing research findings about the effects of heat stress on the working population in relation to climate change. In the light of climate change adaptation, the purpose of the literature review was to explore recent and previous research into the impacts of heat stress on humans in an occupational setting. Heat stress in the workplace has been researched extensively in the past however, in the contemporary context of climate change, information is lacking on its extent and implications. The main factors found to exacerbate heat stress in the current and future workplace are the urban 'heat island effect', physical work, individual differences, and the developing country context where technological fixes are often not applicable. There is also a lack of information on the effects on vulnerable groups such as elderly people and pregnant women. As increasing temperatures reduce work productivity, world economic productivity could be condensed, affecting developing countries in the tropical climate zone disproportionately. Future research is needed taking an interdisciplinary approach, including social, economic, environmental and technical aspects.

Investigating claims that a clothed person's mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34 degrees C in ambient temperatures of 10, 20, and 34 degrees C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (E(mass)) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (E(app)) were compared. A clear discrepancy was observed. E(mass) overestimated E(app) in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34 degrees C, apparent latent heat (lambda(app)) of pure evaporative cooling was lower than the physical value (lambda; 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, lambda(app) increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, lambda(app) even exceeds lambda by four times that value at 10 degrees C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

The Universal Thermal Climate Index (UTCI) was conceived as a thermal index covering the whole climate range from heat to cold. This would be impossible without considering clothing as the interface between the person (here the physiological model of thermoregulation) and the environment. It was decided to develop a clothing model for this application in which the following three factors were considered: 1: typical dressing behaviour in different temperatures, as observed in the field, resulting in a model of the distribution of clothing over the different body segments in relation to the ambient temperature, 2: the changes in clothing insulation and vapour resistance caused by wind and body movement, and 3: the change in wind speed in relation to the height above ground. The outcome was a clothing model that defines in detail the effective clothing insulation and vapour resistance for each of the thermo-physiological model's body segments over a wide range of climatic conditions. This paper details this model's conception and documents its definitions.

Increasing concern about energy consumption and the simultaneous need for an acceptable thermal environment makes it necessary to estimate in advance what effect different thermal factors will have on the occupants. Temperature measurements alone do not account for all climate effects on the human body and especially not for local effects of convection and radiation. People as well as thermal manikins can detect heat loss changes on local body parts. This fact makes it appropriate to develop measurement methods and computer models with the corresponding working principles and levels of resolution. One purpose of this thesis is to link together results from these various investigation techniques with the aim of assessing different effects of the thermal climate on people. The results can be used to facilitate detailed evaluations of thermal influences both in indoor environments in buildings and in different types of vehicles. This thesis presents a comprehensive and detailed description of the theories and methods behind full-scale measurements with thermal manikins. This is done with new, extended definitions of the concept of equivalent temperature, and new theories describing equivalent temperature as a vector-valued function. One specific advantage is that the locally measured or simulated results are presented with newly developed "comfort zone diagrams". These diagrams provide new ways of taking into consideration both seat zone qualities as well as the influence of different clothing types on the climate assessment with "clothing-independent" comfort zone diagrams.Today, different types of computer programs such as CAD (Computer Aided Design) and CFD (Computational Fluid Dynamics) are used for product development, simulation and testing of, for instance, HVAC (Heating, Ventilation and Air Conditioning) systems, particularly in the building and vehicle industry. Three different climate evaluation methods are used and compared in this thesis: human subjective measurements, manikin measurements and computer modelling. A detailed description is presented of how developed simulation methods can be used to evaluate the influence of thermal climate in existing and planned environments. In different climate situations subjective human experiences are compared to heat loss measurements and simulations with thermal manikins. The calculation relationships developed in this research agree well with full-scale measurements and subject experiments in different thermal environments. The use of temperature and flow field data from CFD calculations as input produces acceptable results, especially in relatively homogeneous environments. In more heterogeneous environments the deviations are slightly larger. Possible reasons for this are presented along with suggestions for continued research, new relationships and computer codes.Key-words: equivalent temperature, subject, thermal manikin, mannequin, thermal climate assessment, heat loss, office environment, cabin climate, ventilated seat, computer model, CFD, clothi...

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