(1) The amount of heat produced by the body increases directly with
increasing work. Therefore, reduction of workload markedly decreases the total heat
(2) Workloads and/or duration of physical exertion should be less during the
first days of exposure to heat and should be gradually increased to allow
(3) Decisions to modify work schedules must be governed by the particular
local situation, but generally heavy work should be scheduled for the cooler hours of the
day--early morning or late evening.
(4) Alternate work and rest periods are desirable. Under moderately hot
conditions, five-minute rest periods in the shade alternating with 25 minutes of work in
the sun may be desirable. Under severe conditions, the duration of rest should be
(5) Exposure to high temperature at night as well as in the daytime will
decrease the amount of work individuals can perform effectively.
(6) Reduce work loads at high temperatures when personnel become
dehydrated from excess sweating and there is a lack of water. When there is a
shortage of water, schedule work in the early morning and evening. At these times,
individuals can accomplish more work with less expenditure of water (sweating) than
possible in the hotter hours of the day.
Avoid having any individual work in the direct sun on hot days, as far as
(8) Avoid personnel standing at attention in the heat unnecessarily.
Continued standing places an added burden on the body's circulation.
(9) Curtail physical work when the temperature is excessively
high; under extreme conditions, suspend work. The temperature at which work should
be curtailed or suspended depends on the humidity, radiant heat, air movement,
character of the work, degree of acclimatization of personnel, and other factors. Heat
casualties have been observed when the wet bulb globe temperature (WGBT) is 75F
(24C) and lower. Overexertion can cause heat injury at even lower temperatures,
especially if the person is wearing a heavy uniform or mission-oriented protective
posture clothing, commonly called MOPP gear. MOPP gear is vapor impermeable
clothing and allows no airflow to get through the clothing; consequently, the person
wearing it can become very hot.