2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
PRACTICAL USE OF THERMAL MODEL FOR EVALUATION OF
HUMAN STATE IN HOT ENVIRONMENT:
SUMMARY OF FRENCH - UKRAINIAN PROJECT
Irena Yermakova 1 & Victor Candas 2
1 International Center for Information Technologies and Systems UNESCO, Kiev, Ukraine.
2 Centre d`Etudes de Physiologie Appliquée (CNRS), Strasbourg, France.
Contact person: irena@zeos.net
INTRODUCTION
One advantage of thermoregulatory modelling is the prevention of thermal injury during
exposure to hot environments. In particular, the ability to predict the dynamics of the
regulatory processes and to study quantitative changes that take place in the thermal system.
The scientific field of modelling the human thermoregulatory system has a long and
distinguished history, with many eminent scientists contributing to this effort. A milestone in
this historical development is certainly the contribution of Stolwjik (1970).
Although perhaps curiosity-driven at first, thermoregulatory models are of increasingly
practical value in different areas: aerospace industry, building, textile industry, automobile
industry, etc.
The aim of this paper is to illustrate the abilities of the developed computer simulator for
practical analysis of thermophysiological behaviour of the human in hot environments. This is
a short summary of a French-Ukrainian cooperative project.
METHOD
Multicompartmental thermal models were implemented in an object-oriented approach and
were realised as a computer simulator [1]. The mathematical foundation of the models is a set
of differential equations describing heat exchange, and the control thermal processes in
humans. The human thermoregulatory system is divided into passive and active systems. The
passive system takes into consideration heat production in organs and tissues, heat transfer by
blood flows and by conductive pathways, evaporation from skin and respiratory system, heatexchange
with the environment through convection and radiation. The active system includes
afferent pathways from the skin and core to the brain, and efferent pathways involved in the
regulatory responses of vasomotor activity, sweating and shivering. The computer simulator
accounts for any non-uniformity of the environment, and different levels of physical activity.
It allows simulation of different clothing composed from available textile databases [2, 3]. A
microclimate cooling analysis was also incorporated [4], allowing two modes of simulations:
whole body, or regional cooling (torso, head and/or others). The model allows the simulation
of not only the effects of the environment, but also of clothing, physical activity, and
microclimate cooling system
Simulations illustrate transient and steady state responses of body temperatures, total and
local sweat evaporation, evaporative and dripping sweat rates, total water losses, wettedness
and sweat efficiency, cardiac output and heart rate, and skin blood flow.
We present the results of two modelling experiments investigating the impact of humid and
dry hot environmental conditions on human thermoregulatory responses.
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