The Effects of Metabolic Work Rate and Ambient Environment on Physiological Tolerance Times While Wearing Explosive and Chemical Personal Protective Equipment

Table 2

Tolerance time (mean, range) and termination criteria across the different environmental conditions and work rates ( = 12).

WBGT (°C)	Speed (km·h^−1)	Tolerance time (min)	HR (>90% max)	(>39°C)	Fatigue or nausea	Duration (=60 min)
21	2.5	52.1 (27.5–60)^b,c	4			8
	4	36.0 (18–53)^b	8	1	3
	5.5	20.4 (6.5–39)	11	1
30	2.5	39.1 (18.5–51.5)^a,b,c	9	2	1
	4	27.4 (12–47.5)^b	11		1
	5.5	16.9 (9–28.5)	12
37	2.5	33.5 (13.5–44.5)^a,b,c,d	8	1	3
	4	24.7 (9–33)^a,b	11	1
	5.5	15.1 (6–25.5)	11		1

Values are mean (range). Main effect observed for environment (WBGT37 < WBGT30 < WBGT21; < 0.001), work intensity (5.5 < 4 < 2.5 km·h⁻¹; < 0.001), and their interaction ( < 0.001). WBGT, wet bulb globe temperature; HR, heart rate; , core temperature. ^aSignificantly different to the same speed at WBGT 21°C ( < 0.05); ^bsignificantly different to 5.5 km·h⁻¹ at the same environmental condition ( < 0.05); ^csignificantly different to 4 km·h⁻¹ at the same environmental condition ( < 0.05); ^dsignificantly different to the same speed at WBGT 30°C ( < 0.05).