(1) Prevention of heat injuries depends largely on educating two groups of
people: personnel who will be exposed to extreme heat and those who supervise these
personnel. Everyone who will be exposed to unaccustomed high temperatures,
personnel and their supervisors or commanders, should be aware of the following:
(a) The potentially serious results of heat injury.
The general nature of heat injuries.
How heat injuries can be prevented.
(2) Supervisors and responsible officers must be able to identify
environmental conditions which make heat injuries likely to happen. They should be
able to recognize the earliest signs of heat injury and take appropriate action to prevent
the heat injury from happening. For example, mental confusion and overactivity
commonly precede collapse from heatstroke. Supervisors must be alert to detect these
conditions, then to enforce rest, and next to obtain medical assistance promptly.
(3) Responsible medical officers should assist commanders in the
development of local programs for heat injury prevention and continuously observe and
advise in its application.
(4) All personnel should be trained so that each person is capable of
administering effective first aid for heat injury.
4-29. WET BULB GLOBE TEMPERATURE (WBGT) INDEX
a. Equipment. The WBGT index is computed from readings of the following: a
stationary wet bulb thermometer exposed to the sun and to the prevailing wind; a six
inch black globe thermometer similarly exposed; and a dry bulb thermometer shielded
from the direct rays of the sun. All readings are taken at a location representative of the
conditions to which people are exposed. The web bulb and globe thermometers are
suspended in the sun at a height of four feet above ground. A period of at least 20
minutes should elapse before readings are taken.
(1) The wet bulb thermometer. This thermometer is a standard laboratory
glass thermometer with its bulb covered with a wick (heavy white shoe-string). The wick
dips into a flask of clean, preferably distilled, water. The mouth of the flask should be
about three-fourths of an inch below the tip of the thermometer bulb. The water should
be changed daily after rinsing out the flask and washing the wick with soap and water.
To avoid incorrect readings, the water and wick must be free of salt and soap.