6
was located (Figure 5f, 5g, 5h). The combustion container,
within the 3-story maze (25 m × 7 m) had an average
of around 90 to 100 degrees Celsius and a maximum of
140 degrees Celsius, where smartphones may have a high
chance of being shut down. This is where firefighting exer-
cises were undertaken.
After completion of the daily training, all record-
ing devices were deactivated, and the collected data was
explained to the participants. After the 3-day testing period
RESULTS AND DATA ANALYSIS
Quantitative Assessment
The correlation of measured HR and estimated TC to vari-
ous mine rescue activities and job functions was examined
to determine the feasibility of using HR as an indicator for
the monitoring and prevention of heat stress and physi-
ological strain (1). The ECTemp algorithm used sequen-
tial HR values and a Kalman filter to estimate TC, (29).
Figure 6 shows the trial’s participants’ HR and estimated
TC throughout the trial. Figure 6a shows the HR of the
participants for the last day of the trial. Average baseline
HR was 99.50 ± 21.49 BPM and rose to an average peak
HR value of 159.12 ± 14.99 BPM. The range of HR was
92.88 ± 13.60 BPM. During the trial, TC changed gradu-
ally from an average baseline TC of 37.46 ± 0.45 °C to an
average peak TC of 38.20 ± 0.44 °C (Figure 6b). The range
of TC was 1.22 ± 0.41 °C.
Figure 7 further highlights the personal nature of TC
and its alignment with various activities throughout the day.
Generally, individuals’ TC peaked between 13:30 and
14:30 hours. This specific timeframe coincides with the
period during which participants were actively engaged in
physically demanding activities i.e., firefighting or search
&rescue within the maze in hot and humid conditions.
The synchronized elevation in both HR and TC during this
phase underscores the intricate connection between the car-
diovascular system and the body’s TC regulation mecha-
nisms, offering valuable insights into the participants’
physiological responses during these challenging condi-
tions. Participants 006 and 007, who participated as train-
ees, vice-captain and FAB on that day: exhibited a rise and
fall of the HR and TC, which meaningfully corresponds
with their type of activity as well as their intensity of work.
For instance, between 13:45 and 14:30, while Simtars 001
and Simtars 006 are resting after the firefighting activity,
allowing their HR and TC to decrease, Simtars 007 starts
cleaning the room, which elevates his HR and TC.
These findings are consistent with prior findings [28,
29, 30], which indicate that HR as a potential marker of
heat stress, displays a similar pattern to TC, albeit with a
slight time delay. The estimated TC data was compared
with the established guidelines [31], which allowed an
assessment of an individual’s temperature concerning
safe limits (Figure 7) and thus allowing a quick and clear
evaluation of whether TC values were approaching a criti-
cal point, helping in the early detection of potential heat-
related health risks.
Metabolic rate was estimated by SafeGuard using HR
values measured by the PVS. Metabolic rate can provide
useful insights in assuring that participants were not sub-
jected to excessive physical strain, which can lead to fatigue,
accidents, and injuries over extended periods. Figure 8
shows the data acquired for Simtars 001, who had an
increase in metabolic rate during the firefighting activity.
However, since a specific amount of time that universally
Figure 5. Field trial activities. a) LDBA preparation, b) LDBA pack marching, c-d) container training, e) FAB, f) maze, hot
and humid training, g) mine rescue, h) firefighting
was located (Figure 5f, 5g, 5h). The combustion container,
within the 3-story maze (25 m × 7 m) had an average
of around 90 to 100 degrees Celsius and a maximum of
140 degrees Celsius, where smartphones may have a high
chance of being shut down. This is where firefighting exer-
cises were undertaken.
After completion of the daily training, all record-
ing devices were deactivated, and the collected data was
explained to the participants. After the 3-day testing period
RESULTS AND DATA ANALYSIS
Quantitative Assessment
The correlation of measured HR and estimated TC to vari-
ous mine rescue activities and job functions was examined
to determine the feasibility of using HR as an indicator for
the monitoring and prevention of heat stress and physi-
ological strain (1). The ECTemp algorithm used sequen-
tial HR values and a Kalman filter to estimate TC, (29).
Figure 6 shows the trial’s participants’ HR and estimated
TC throughout the trial. Figure 6a shows the HR of the
participants for the last day of the trial. Average baseline
HR was 99.50 ± 21.49 BPM and rose to an average peak
HR value of 159.12 ± 14.99 BPM. The range of HR was
92.88 ± 13.60 BPM. During the trial, TC changed gradu-
ally from an average baseline TC of 37.46 ± 0.45 °C to an
average peak TC of 38.20 ± 0.44 °C (Figure 6b). The range
of TC was 1.22 ± 0.41 °C.
Figure 7 further highlights the personal nature of TC
and its alignment with various activities throughout the day.
Generally, individuals’ TC peaked between 13:30 and
14:30 hours. This specific timeframe coincides with the
period during which participants were actively engaged in
physically demanding activities i.e., firefighting or search
&rescue within the maze in hot and humid conditions.
The synchronized elevation in both HR and TC during this
phase underscores the intricate connection between the car-
diovascular system and the body’s TC regulation mecha-
nisms, offering valuable insights into the participants’
physiological responses during these challenging condi-
tions. Participants 006 and 007, who participated as train-
ees, vice-captain and FAB on that day: exhibited a rise and
fall of the HR and TC, which meaningfully corresponds
with their type of activity as well as their intensity of work.
For instance, between 13:45 and 14:30, while Simtars 001
and Simtars 006 are resting after the firefighting activity,
allowing their HR and TC to decrease, Simtars 007 starts
cleaning the room, which elevates his HR and TC.
These findings are consistent with prior findings [28,
29, 30], which indicate that HR as a potential marker of
heat stress, displays a similar pattern to TC, albeit with a
slight time delay. The estimated TC data was compared
with the established guidelines [31], which allowed an
assessment of an individual’s temperature concerning
safe limits (Figure 7) and thus allowing a quick and clear
evaluation of whether TC values were approaching a criti-
cal point, helping in the early detection of potential heat-
related health risks.
Metabolic rate was estimated by SafeGuard using HR
values measured by the PVS. Metabolic rate can provide
useful insights in assuring that participants were not sub-
jected to excessive physical strain, which can lead to fatigue,
accidents, and injuries over extended periods. Figure 8
shows the data acquired for Simtars 001, who had an
increase in metabolic rate during the firefighting activity.
However, since a specific amount of time that universally
Figure 5. Field trial activities. a) LDBA preparation, b) LDBA pack marching, c-d) container training, e) FAB, f) maze, hot
and humid training, g) mine rescue, h) firefighting