2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
Table 1: Mean skin temperature response by condition (mean ± SD).
C n
202
Mean
Duration
(min)
Skin Temperature
"Start"
( ° C)
"Stop"
( ° C)
Rise ( ° C)
Rate of Rise
( ° C.min -1 )
C1 10 58.3 ± 5.6 33.7 ± 0.4 35.9 ± 0.6 2.2 ± 0.6 0.04 ± 0.01
C2 8 59.9 ± 14.2 34.3 ± 0.6 36.8 ± 0.4 2.5 ± 0.6 0.04 ± 0.01
C3 12 55.9 ± 10.1 33.6 ± 0.4 35.8 ± 0.5 2.2 ± 0.4 0.04 ± 0.01
C4 10 61.4 ± 13.6 33.9 ± 0.6 36.9 ± 0.4 3.0 ± 0.8 0.05 ± 0.01
Total 40 58.7 ± 10.9 33.9 ± 0.6 36.3 ± 0.7 2.5 ± 0.7 0.04 ± 0.01
Thermal sensation
9
8
7
6
5
4
3
2
1
0
Figure 2: Ratings of thermal sensation by condition.
Start Stop
C1 C2 C3 C4
Sweat rate averaged 0.022 L.min -1 across all conditions, and whilst there was no
significant difference (p=0.114), the highest sweat rate was seen in Condition 4 (GTS
and travelator on), corresponding to a rate of ~1.6 L.hr -1 . At this sweat rate, it would
take approximately 60 min to achieve a ~2% loss in body mass.
Ratings of thermal sensation showed slightly lower, although not significant, baseline
and final values for the NPPE conditions (C1 and C3) compared to the GTS
conditions (C2 and C4) (Figure 2). This may be the result of the different
microclimate within the GTS. Although there was little difference in the temperature
between wear conditions (~22ºC) the GTS conditions did produce a far greater
relative humidity (~96% RH versus ~45% RH).
DISCUSSION
In summary, these data show that both ensembles elicited a high Tc response, with
temperatures exceeding 39 ° C in 28% of subjects. Thirteen percent of subjects had to
be withdrawn from the trials and actively cooled due to attaining the threshold Tc
(39.5°C). Further rises in Tc in these subjects could have resulted in significant health
complications together with marked reductions in work capacity. Sweat rate was also
high, the highest observed being equivalent to a body mass loss of 2% in one hour, a