Page 127 - Participant Manual

Exposure Injuries and Illnesses

Thermoregulation, or the body’s ability to maintain an
internal temperature within an acceptable range despite
external conditions, is important for human survival. The
body uses various methods to achieve thermoregulation.
For example, sweat evaporating from the skin helps to cool
the body, and the muscle contractions caused by shivering
help to warm the body. Usually the body is able to maintain
a normal body temperature despite exposure to hot or cold
external temperatures. However, under certain conditions
(such as prolonged exposure to heat or cold, heavy exertion,
inadequate fluid intake, or exposure to extreme heat or
extreme cold), the body’s thermoregulatory mechanisms can
become overwhelmed, leading to life-threatening illness.
People who are at increased risk for experiencing a first aid
emergency due to exposure to heat or cold include:

■ Those who work or exercise outdoors.
■ The elderly and the young.
■ Those with medical conditions that cause poor
blood circulation.
■ Those who take diuretics (medications that
promote the elimination of water from the
body).

Heat-Related Illnesses

Heat-related illnesses are caused by
overexposure to heat and the loss of fluids and
electrolytes. While being outdoors is a risk
factor for developing a heat-related illness,
these illnesses can also affect people who are
indoors. People who live or work in buildings
that are inadequately cooled or ventilated are at
risk, as are those who perform indoor jobs in hot
environments (e.g., kitchen and laundry workers,
© 2011, 2016 The American National Red Cross. All rights reserved.
factory workers). People who habitually work or
exercise in hot environments tend to become
more tolerant of the heat over time but may still
be at risk for developing heat-related illnesses,
especially when environmental temperatures are
very high (e.g., greater than 100° F or 38° C).

Although extremely high environmental temperatures increase the risk for heat-related illnesses, these
illnesses can also occur at more moderate environmental temperatures. For example, a person who is doing
strenuous work and is clothed in heavy protective clothing may be at risk for experiencing a heat-related
illness at a lower environmental temperature. Similarly, a person who is unaccustomed to doing strenuous
labor or exercising in the heat may develop a heat-related illness at lower environmental temperatures. Other
factors, such as humid air, inadequate fluid intake and personal characteristics (e.g., the presence of certain
medical conditions, the person’s age) can increase the risk for heat-related illness.
The three types of heat-related illnesses (in order from least to most severe) are heat cramps, heat exhaustion
and heat stroke.

Chapter 7 Environmental Injuries and Illnesses | 119 | First Aid/CPR/AED Participant’s Manual