2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
results also showed that the mean performance time of the 'search-and-rescue' task
during the combined bicycle ergometer test / ‘search-and-rescue’ task was 6,2%
higher when compared to the single ‘search-and-rescue’ task.
Table 2 Results of search and rescue task
198
Search and rescue with pre-exercise Search and rescue without pre-exercise
Mean SD Min Max Mean SD Min Max
Tcore (°C) 37.9 0.3 38.4 37.4 0.4 38.2 0.00
Δ Tcore (°C) 0.31 0.14 0.59 0.37 0.08
Tskin (°C) 36.4 0.8 33.4 1.4 0.54
RPE 13.6 1.5 11 15 13.0 1.3 11 15 0.08
TS 1.9 0.7 1 3 2.5 1.2 1 4 0.49
Perf.time
(mm:ss)
P-
value
15:07 00:29 14:39 15:43 14:44 01:00 12:47 15:37 0.38
DISCUSSION
The main conclusion that can be drawn, is that heat stress is a multidimensional
problem, but that the main cause of the problems, as previously determined by these
fire fighters, is not their protective clothing. We noticed that behavioural aspects of
fire fighters are more important in causing heat stress. It is concluded that moderate,
non-fire fighting related exercise prior to a fire fighting task leads to a higher core
temperature during fire fighting. Consequently, earlier onset of symptoms of heat
stress during a common fire fighting task then may occur.
The conclusions on the sub questions are as follows:
Textile properties may change in time due to use and ageing; most important is the
decreased water vapour permeability. Decreased water vapour permeability may lead
to a worse evaporation and subsequently to an increase in heat load on the body.
However the duration of smoke diving tasks is generally shorter than is predicted by
THDYN even with the deteriorated water vapour membrane. Changes in the other
properties of the textile material of the garments in this study are of minor influence
on the thermal load of the fire fighter.
The structured interviews showed that heat stress is a multidimensional problem that
can be divided into two main categories, namely human related causes and technical
causes. However the seriousness of the problem of heat stress is often still not
recognised. The common thought is that it is part of the job.
The experiments on the influence of pre-exercise showed that elevated exercise levels
prior to a fire fighters’ search and rescue task may lead to shorter exposure times.
More research to the heat balance of fire fighters on duty is needed to regulate the
work rest cycles of their job.
ACKNOWLEDGEMENTS
We would like to thank the Amsterdam Fire Brigade for their financial support of this
study and the cooperative participation of the fire fighters in the experiments.