Industrial Hygiene

Fort Detrick
Industrial Hygiene & Environmental Health Office

Heat Stress Index

Heat Stress Index is OFFLINE and will resume when hot weather arrives.

Work/Rest Cycles & Water Intake

Use heat condition information below to determine required water intake and work/rest cycles.

Heat
Category		 WBGT
INDEX
(° F)		 Easy
Work/Rest
(Minutes)		 Water
Intake/Hr
(Qts)		 Moderate
Work/Rest
(Minutes)		 Water
Intake/Hr
(Qts)		 Hard
Work/Rest
(Minutes)		 Water
Intake/Hr
(Qts)
0 < 78 NL N/A NL N/A NL N/A
1 78-81.9 NL 1/2 NL 3/4 40/20 3/4
2 82-84.9 NL 1/2 50/10 3/4 30/30 1
3 85-87.9 NL 3/4 40/20 3/4 30/30 1
4 88-89.9 NL 3/4 30/30 3/4 20/40 1
5 > 90 50/10 1 20/40 1 10/50 1

N/A - Not Applicable
NL - No Limit

Definitions

Easy Work Moderate Work Hard Work
  • Weapon Maintenance
  • Walking Hard Surface at 2.5 mph, with ≤ 30 lb Load
  • Manual of Arms
  • Drill and ceremony
  • Marksmanship Training
  • Walking in loose sand at 2.5 mph, no load
  • Walking Hard Surface at 3.5 mph, < 40 lb Load
  • Calisthenics
  • Patroling
  • Individual Movement Techniques. i.e. low crawl, high crawl
  • Defensive Position Construction
  • Field Assaults
  • Walking in loose sand at 2.5 mph with load
  • Walking Hard Surface at 3.5 mph, with ≥ 40 lb Load
  • The work/rest time and fluid replacement volumes will sustain performance and hydration for at least 4 hours of work in the specified heat category. Individual water needs will vary ± ¼ qt/hr.
  • NL= no limit to work time per hour.
  • Rest means minimal physical activity (sitting or standing) and should be accomplish in shade if possible.

CAUTION

  • Hourly fluid intake should not exceed 1 ½ quarts.
  • Daily fluid intake should not exceed 12 quarts.
  • Wearing body armor adds 5°F to WBGT index.
  • Wearing MOPP over garment adds 10°F to WBGT Index