Page 205 - Safety Memo

HEAT STRESS PROGRAM

There are a number of steps that can be taken, either alone or in combination with others, to reduce and
control the hazards of heat stress in the workplace. These guidelines are designed to aid in that task.

This section applies to all Company operations.

POLICY

Occupational heat-related disorders and accidents must be prevented. A Heat Stress Program will be
implemented whenever a heat stress environment exists. If preventive measures are not effective, worker
monitoring and control measures will be implemented.

GENERAL

Although no one questions that there is an association between heat stress and occupational accidents, it is
difficult to predict just who will be affected and when. Two people can work at the same job, under the
same conditions, and while one will be affected by the heat, the other will not. Age, weight, physical
fitness, metabolism, alcohol or drug use, and medical condition are some of the determining factors
affecting a person's sensitivity to heat and susceptibility to heat disorders. Even the type of clothing worn
must be considered. In addition, the measurement of a hot environment involves more than just
measuring the ambient air temperature: radiant heat, air movement, and relative humidity are all factors
that must be determined.

Heat-induced occupational illnesses, injuries and reduced productivity occur in situations in which the
total heat load exceeds the capacities of the body to maintain normal body functions without excessive
strain. Many of the bodily responses to heat exposure are desirable and beneficial. However, at some
level of heat stress, the worker's compensatory mechanisms will no longer be capable of maintaining
body temperature at the level required for normal body functions. As a result, the risk of heat-induced
illnesses, disorders and accidents substantially increases.

HEAT DISORDERS (Table 1)

Heat stress causes body reactions, and as we have mentioned above, there are four environmental factors
that affect the amount of stress a worker faces in a hot work area temperature, humidity, radiant heat
(such as from a furnace or live steam pipes), and air movement. The body reacts to high external
temperature by circulating blood to the skin which increases skin temperature and allows the body to give
off its excess heat through the skin. However, if the muscles are being used for physical labor, less blood
is available to flow to the skin and release the heat.

Sweating is another means the body uses to maintain a stable internal body temperature in the face of
excessive heat. However, sweating is effective only if the humidity level is low enough to permit
evaporation and if the fluids and salts lost are adequately replaced. Of course, there are many steps a
person might choose to take to reduce the risk of heat stress, such as moving to a cooler place, reducing
the work pace or load, or removing or loosening some clothing. But this is not always practicable or
possible during the work situation.

If the body cannot dispose of excess heat, it will store it. When this happens, the body's core temperature
rises and the heart rate increases. As the body continues to store heat, the individual begins to lose
concentration and has difficulty focusing on a task, he may become irritable or sick, and often loses the

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