‘Alarm’ and ‘Danger’ Criteria in Foot Temperature to
Prevent Heat Stroke in Workers Wearing Personal Protective Clothing
Joo-Young
Kouhei
1
NAKAO ,
Methods
 A total of 20 experimental conditions through 2 series of studies with
16 subjects (8+8 subjects)
o [Series 1] 12 conditions
= three clothing ensembles ×
two air temp. (25 & 32oC,
50%RH) × two activities
o [Series 2] 8 conditions
= Four types of firefighter’s PPE ×
two air temp. (22 & 32oC, 50%RH) × o
ne activity
SCBA (Self-Contained Breathing Apparatus)
No SCBA
Control
3 Clothing ensembles
Control Tyvek Vinyl
Type A
Type B
Type C
 In most cases,
mean Tsk was lower
than Tfoot,
10
9
8
7
• 1,245 g
• 1.46 clo
2 Activities
Old straps
0
10
19.27 kg
> 14.67 kg =
Sitting
30
40
o
25 C-Vinyl
34
Run
Run
Run
Run
Run
Run
38
36
Tre
Tfoot
35
Mean Tsk
34
Run
20
Run
40
Run
60
80 0
32oC-Vinyl
32oC-Tyvek
32oC-Control
Run
Run
20
40
60
Time (min)
Time (min)
80 0
20
Run
40
60
80
Time (min)
Fig. 1. [Series 1] Time course of rectal (Tre), foot (Tfoot)
and mean skin temperatures (mean Tsk) during exercise.
-3 r=-0.618, p<0.01
Very
uncomfort. (N=48)
r=0.863, p<0.01
(N=48)
4 r=-0.640, p<0.01
Very
(N=48)
hot
-2
3
Uncomfort.
Hot
6
5
-1
4
3
37.6oC Tfoot 6.0 PSI
38.6oC Tfoot 8.0 PSI
2
Slightly
uncomfort.
0
2
Old strap
Heavy Gas-cylinder
Old Strap
Light Cylinder
New strap
Light Cylinder
Running
Stabil.
Sitting
60
80 min
0
10
Improved straps
Running
Sitting
40
60 min
180
160
140
120
100
80
60
165bpm
Tfoot
HR
Exercise
Exercise
32oC-Control
Exercise
Exercise
32oC-Type B
32oC-Type A
32oC-Type C
Danger
Alarm
165bpm
Exercise
0 10 20 30 40 50 60 0 10 20 30 40 50 60
Time (min)
180
160
140
120
100
80
60
Exercise
Exercise
0 10 20 30 40 50 60 0 10 20 30 40 50 60
Time (min)
Time (min)
Heart Rate (bpm)
Temperature (oC)
Tfoot
Alarm
Fig.3. [Series
2] Alarm and
Danger
criteria on the
time course of
rectal (Tre),
foot (Tfoot) and
heart rate
during
exercise
wearing
various SCBA .
Time (min)
37
0
25 C (3 conditions)
32oC (3 conditions)
22oC-Type C
 The ‘Alarm’ and ‘Danger’ criteria in Tfoot were then evaluated with new
data set drawn from Series 2 (Fig. 3).
39
33
o
22oC-Type B
Heart Rate (bpm)
35
22oC-Type A
Tre
Exercise
36
Warm
37.4oC Tfoot
38.6oC Tfoot
Uncomfortable
Very uncomfortable
36
37
38
39
Foot temperature, Tfoot (oC)
1
37.4oC Tfoot
38.4oC Tfoot
Hot
Very hot
36
37
38
39
Foot temperature, Tfoot (oC)
14.67kg
Exercise
6-8 km·hr-1
Running
37
Fig. 2. [Series 1] Relationships of foot temperature with physiological strain index
(Left), thermal comfort (middle), and thermal sensation (Right)
 PPE total weight 8.27 kg
Stabil.
38
33
36
37
38
39
Foot temperature, Tfoot (oC)
Rest
25oC-Tyvek
25oC-Control
39
38
37
36
35
34
33
32
22oC-Control
 PSI: Tfoot of 37.6oC & 38.6oC  PSIs of 6.0 & 8.0, respectively
 Thermal comfort: Tfoot of 37.4oC & 38.6oC  ‘uncomfortable’ &
‘very uncomfortable’.
 Thermal sensation: Tfoot of 37.4oC & 38.4oC  ‘hot’ & ‘very hot’
Tfoot of 38.5oC was set as a ‘Danger’ level. For an initial warning value
(Alarm), Tfoot of 38.0oC was tentatively determined from the half value
between ‘uncomfortable’ and ‘very uncomfortable’, ‘hot’ and ‘very hot’.
 Fig. 4 (Left): The point of showing the identical value between Tfoot
and Tre was 38oC. This indicates that as Tfoot rises up to 38oC, Tfoot then
becomes greater than Tre, which means that temperature distribution
between the core and shell is rever-sed at the Tfoot of 38oC.
Fig. 4. [Series 1 & 2]
Relationships
between foot
temperature and
rectal temperature
(left); foot
temperature and
heart rate (right)
39.0
200
[Series 1] Tair 32oC
[Series 2] Tair 32oC
Heart rate, HR (bpm)
invasive and simpler criterion to assess the heat strain of PPE-workers.
 Tfoot reached Tre
for the cases where
Tyvek coverall was
worn at 32oC.
 For Vinyl condition
at 32oC, Tfoot finally
exceeded Tre during
exercise.
39
39
38
37
36
35
34
33
32
Rectal temperature (oC)
 Purpose: Investigation of the feasibility of foot temperature as a non-
Results
Temperature (oC)
ment (PPE) in hot environments often encounter
severe heat stress. To prevent heat stroke, numerous criteria have been put forth as guidelines:
ISO 7243 (Wet Bulb Globe Temperature Index ,
WBGT) set “Safe” WBGTs.: ISO 7933 (2004)
Japan Atomic Energy Agency provides physiological criteria for determining
the maximum allowable exposure. However, the real-time monitoring of
physiological variables during working is relatively less feasible for
workers equipped with full protective clothing. To facilitate the assessment of the thermal state of PPE-workers, the development of nonInvasive and simpler measurements is needed as a valid criterion.
Temperature (oC)
 Workers wearing personal protective equip-
Vinyl suit
• 787 g
• 1.39 clo
Yutaka
1
TOCHIHARA
 Measurements
: Skin temp. on 11 sites (2s), Rectal temp: Tre (2s), Heart rate (2s),
Total sweat rate, Thermal sensation (10min),Thermal comfort (10min).
 Calculation
: Physiological Strain Index (PSI)
Temperature (oC)
Backgrounds
• 590 g
• 1.05 clo
Ilham
1.3
BAKRI
Department of Human Science, Kyushu University, Japan; 2Japan Society for Promotion of Science (JSPS); 3 Engineering Department, Hasanuddin University, Indonesia
Physiological Strain Index, PSI
1
1,2*
LEE ,
38.5
38.0
37.5
38.05
r=0.486,
p<0.01
37.0
Alarm
36.5
36.5
37
37.5
38
Danger
38.5
Foot temperature (oC)
39
190
180
170
174bpm
164bpm
160
150
140
r=0.593,
p<0.01
130
Alarm
120
36.5
37
37.5
38
Danger
38.5
39
Foot temperature (oC)
Summary and Conclusions
Tfoot of 38.0 and 38.5oC were determined as Alarm and Danger
criteria, respectively.
The Alarm level was set at the point that Tfoot reached rectal
temperature during exercise.
The Danger level was determined at the moments that extreme
subjective perceptions were given (very uncomfortable, very hot,
and very hard).
The Alarm and Danger criteria that derived from Tfoot are valid for
workers wearing full protective clothing (including protective boots)
in hot environments, but cannot be applied to workers wearing light
work wear in thermal neutral environments.
*Correspondence: Joo-Young LEE (leex3140@design.kyushu-u.ac.jp)