a. The amount of heat produced by the body increases directly with increasing
work. Therefore, reduction of workload markedly decreases the total heat stress.
b. 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 acclimatization.
c. While decisions to modify work schedules must be governed by the particular
local situation, heavy work should be scheduled for the cooler hours of the day, such as
early morning or late evening.
d. Alternate work and rest periods may prove desirable. Under moderately hot
conditions, 5-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 periods should be
e. Exposure to high temperature at night as well as in the daytime will decrease
the amount of work men can perform effectively.
f. Workloads must be reduced at high temperatures when dehydration resulting
from excess sweating and lack of water replacement occurs. When water is in short
supply, working in the early morning and evenings will allow much more work to be
accomplished for the expenditure of a given amount of water than working during the
hottest hours of the day.
g. Work in the direct sun should be avoided as far as possible on hot days.
h. Unnecessary standing at attention in the heat should be avoided, because
continued standing places an added burden on the circulation.
i. When the temperature is excessively high, physical work should be curtailed
or, under extremely severe conditions, even suspended. The temperature at which
work should be curtailed or suspended depends on the humidity, heat radiation, air
movement, character of the work, degree of acclimatization of personnel, and other
factors. Heat casualties may be expected at wet bulb temperatures of 75F and above
unless preventive measures are instituted. Overexertion can cause heat injury at even
4-19. PROTECTION FROM THE ENVIRONMENT
Except when exposed to the sun's rays, an individual in a hot environment is
better off wearing the least allowable amount of clothing. Clothing reduces the
exposure of the body surface to solar radiation but to get that advantage of its benefits
and minimize its disadvantage, clothing should be loose fitting---especially at neck,
wrists, and lower legs--to allow circulation of air. Protection from the environment also
includes such simple but frequently overlooked things as marching troops over grass
rather than concrete and operating in as much shade as is available.