Heat-related Illnesses
???? Know that heat exhaustion and other heat-related illnesses can occur even when the outside temperature isn’t extremely high. Use the National Weather Service’s heat index (which combines air temperature and relative humidity) to tell you how hot it actually feels. *
???? Drink small amounts of water every 20 to 30 minutes when the threat of heat illness is high. Avoid coffee, other drinks with caffeine, and alcohol, which increase your risk of heat illness.
???? Be sure you and your workers are acclimatized to working in the heat. Know that persons who are over 40, overweight, in poor physical condition, or have a past history of heat illness are often more sensitive to the heat.
???? Choose the coolest possible personal protective equipment (PPE) when applying pesticides or other chemicals in hot, humid conditions. Read the product label for the minimum amount of PPE that’s required.
???? Wear light-colored, loose-fitting clothing that reflects the heat and allows your body to release heat. Materials such as cotton or cotton/polyester blends “breathe” and allow air circulation.
???? Take sufficient breaks out of the sun when the heat index is high. Also, try to schedule your most strenuous tasks early in the morning or later in the day.
???? Train your workers to recognize the signs of heat-related illnesses, and to respond appropriately. Know that heat stroke – characterized by excessively high body temperature, confusion, irrational behavior, slowed down or no sweating, rapid breathing and pulse (if conscious), and possible convulsions – can occur suddenly and is a life-threatening medical emergency. Call 911 immediately if heat stroke is suspected.
???? Know that the symptoms of heat exhaustion and organophosphate (OP) poisoning are very similar, but their treatments are very different. Call 911 if you suspect either but are uncertain.

Heat stroke occurs when the body’s system of temperature regulation fails and body temperature rises to critical
levels. This condition is caused by a combination of highly variable factors, and its occurrence is difficult
to predict. Heat stroke is a medical emergency. The primary signs and symptoms of heat stroke are confusion;
irrational behavior; loss of consciousness; convulsions; a lack of sweating (usually); hot, dry skin; and an
abnormally high body temperature, e.g., a rectal temperature of 41°C (105.8°F). If body temperature is too
high, it causes death. The elevated metabolic temperatures caused by a combination of work load and environmental
heat load, both of which contribute to heat stroke, are also highly variable and difficult to predict.
If a worker shows signs of possible heat stroke, professional medical treatment should be obtained immediately.
The worker should be placed in a shady area and the outer clothing should be removed. The worker’s
skin should be wetted and air movement around the worker should be increased to improve evaporative cooling
until professional methods of cooling are initiated and the seriousness of the condition can be assessed.
Fluids should be replaced as soon as possible. The medical outcome of an episode of heat stroke depends on
the victim’s physical fitness and the timing and effectiveness of first aid treatment. Regardless of the worker’s
protests, no employee suspected of being ill from heat stroke should be sent home or left unattended unless a
physician has specifically approved such an order.
The signs and symptoms of heat exhaustion are headache, nausea, vertigo, weakness, thirst, and giddiness.
Fortunately, this condition responds readily to prompt treatment. Heat exhaustion should not be dismissed
lightly, however, for several reasons. One is that the fainting associated with heat exhaustion can be dangerous
because the victim may be operating machinery or controlling an operation that should not be left unattended;
moreover, the victim may be injured when he or she faints. Also, the signs and symptoms seen in heat
exhaustion are similar to those of heat stroke, a medical emergency.
Workers suffering from heat exhaustion should be removed from the hot environment and given fluid
replacement. They should also be encouraged to get adequate rest.
Performing hard physical labor in a hot environment usually causes heat cramps. These cramps have been
attributed to an electrolyte imbalance caused by sweating. It is important to understand that cramps can be
caused by both too much and too little salt. Cramps appear to be caused by the lack of water replenishment.
Because sweat is a hypotonic solution (±0.3% NaCl), excess salt can build up in the body if the water lost
through sweating is not replaced. Thirst cannot be relied on as a guide to the need for water; instead, water
must be taken every 15 to 20 minutes in hot environments.
Under extreme conditions, such as working for 6 to 8 hours in heavy protective gear, a loss of sodium may
occur. Recent studies have shown that drinking commercially available carbohydrate-electrolyte replacement
liquids is effective in minimizing physiological disturbances during recovery.
In heat collapse (fainting), the brain does not receive enough oxygen because blood pools in the extremities.
As a result, the exposed individual may lose consciousness. This reaction is similar to that of heat exhaustion
and does not affect the body’s heat balance. However, the onset of heat collapse is rapid and unpredictable. To
prevent heat collapse, the worker should gradually become acclimatized to the hot
environment.
Heat rashes are the most common problem in hot work environments. Prickly heat is manifested as red
papules and usually appears in areas where the clothing is restrictive. As sweating increases, these papules give
rise to a prickling sensation. Prickly heat occurs in skin that is persistently wetted by unevaporated sweat, and
heat rash papules may become infected if they are not treated. In most cases, heat rashes will disappear when
the affected individual returns to a cool environment.
A factor that predisposes an individual to heat fatigue
is lack of acclimatization. The use of a program of
acclimatization and training for work in hot environments
is advisable. The signs and symptoms of heat
fatigue include impaired performance of skilled sensorimotor,
mental, or vigilance jobs. There is no treatment
for heat fatigue except to remove the heat stress
before a more serious heat-related condition develops.

An effective heat stress program does not begin and end with measurements. Sound industrial hygiene practice
includes worker training and site-specific controls. All managers and workers working in the hot environments
need to be trained on the signs and symptoms of heat stress, how to recognize problems with
themselves and coworkers, how to prevent heat injuries, and what first aid should be administered.
General and job-specific controls can be implemented once the job demands and constraints are understood.
General controls may include: medical screening for fitness; acclimating workers to the heat; allowing selflimited
exposures; encouraging healthy diets and lifestyles; and providing cool water or electrolyte replacement
drinks to encourage frequent drinking. Job specific and engineering controls may include: limiting
exposure times; moving the most strenuous tasks to cooler times of the day; reducing workloads through the use of machinery and tools; using cooling vests; shielding the heat source or providing a sun shade; or
increasing the air flow using fans.

Why should companies be concerned with work to rest regimens when they haven’t had a heat stress related injury in a long time?

INTRODUCTION
At a conference on heat stress, a manager asks: “Why should I put efforts into a heat stress program when I
have not seen a single heat stress injury report over the past nine years?” When this manager was asked if he
looked for trends relating the number of accidents and injuries to
the heat, he admitted that he had not. Reflecting on this, the
manager began to show a deeper interest in the topic. Why? The
potential for accidents and injuries to occur as a result of
heat-induced disorders can represent a greater risk of loss than
the heat-induced disorder itself. A single worker experiencing a
heat-induced disorder can put the safety of an entire work crew,
plant or community at risk.
USER APPLICATION NEWS NOTE 4
HEALTH & OTHER RISKS
Heat tends to promote accidents due to dizziness, the slipperiness
of sweaty palms, or the fogging of safety glasses. Aside from these
more obvious dangers, the frequency of accidents, in general appears to be higher in hot environments than
in more moderate environmental conditions. One reason is that working in a hot environment lowers the
mental alertness and physical performance of an individual. Increased body temperature and physical
discomfort promote irritability, anger, and other emotional states, which sometimes cause workers to
overlook safety procedures or to divert attention from hazardous tasks. Heat stroke, exhaustion, cramps,
collapse, rashes and fatigue are all forms of heat-induced disorders that are either serious health risks
themselves or can lead to serious compromises in safety.
Work/Rest Regimens as a
Heat Stress Management Tool
RO OT CAUSES
Operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with
hot objects, or strenuous physical activities have a high potential for inducing heat stress in employees
engaged in such operations. Such places include: iron and steel foundries, nonferrous foundries, brick-firing
and ceramic plants, glass products facilities, rubber products factories, electrical utilities (particularly boiler
rooms), bakeries, confectioneries, commercial kitchens, laundries, food canneries, chemical plants, mining
sites, smelters, and steam tunnels.
Outdoor operations conducted in hot weather, such as construction, refining, asbestos removal, and hazardous
waste site activities, especially those that require workers to wear semi-permeable or impermeable protective
clothing, are also likely to cause heat stress among exposed workers.

Early in the spring, companies with employees that are exposed to the intense outdoor heat begin their awareness programs. Implementing proper hydration procedures is imperative when working in the heat.

Outdoor Action Guide to Heat-Related
Illnesses & Fluid Balance
by Rick Curtis - Outdoor Action Program, Princeton University

Heat injuries can be immediately life-threatening. Be aware of the temperature conditions and your hydration levels. The information provided here is designed for educational use only and is not a substitute for specific training or experience. Princeton University and the author assume no liability for any individual’s use of or reliance upon any material contained or referenced herein. This article is prepared to provide basic information about heat related illnesses for t e lay person. Medical research is always expanding our knowledge of the causes and treatment. It is your responsibility to learn the latest information. The material contained in this article may not be the most current. Copyright © 1997 Rick Curtis, Outdoor Action Program, Princeton University.

Fluid Balance

All the body’s fluids make up one large body fluid pool. Losses of fluid from any one source is reflected in the levels of all the body’s other fluids: e.g. profuse sweating will ultimately result in decreased blood volume. If a patient loses enough fluid through any manner-bleeding, sweating, vomiting, or diarrhea-the end result is the same: dehydration and, potentially, volume shock. Adequate fluid is also critically important in hot environments to help our body thermoregulate (see Heat llnesses page 00). Remember, dehydration can kill!

If someone is chronically losing fluid (from diarrhea or vomiting), then you have a real emergency on your hands. Treat the cause of the fluid lose as best you can (see Shock page 00, Bleeding page 00, Heat Illnesses page 00, Abdominal Infections page 00) and rehydrate the patient. Be prepared to evacuate your patient.

Dehydration is always easier to prevent than it is to treat. So it is important to ensure that all members of your group replace their regular fluid losses by drinking adequate amounts of water (see below). Your body absorbs fluids best when you drink frequently and in small amounts rather than drinking large amounts at one time. It also helps with fluid absorption if you drink while eating. A pinch of salt and sugar in the water will do if no food is available. Very dilute mixtures of ports drinks like Gatorade® (add just enough to taste) work well for this purpose.

Don’t depend on feeling thirsty to tell you when to drink. Thirst is a late response of the body to fluid depletion. Once you feel thirsty, you are already low on fluids. The best indicator of proper fluid levels is urine output and color. You, and all the people in your group should strive to be “copious and clear.” Ample urine that is light colored to clear shows that the body has plenty of fluid. Dark urine means that the body is low on water, and is trying to conserve its supply by hoar ing fluid which means that urine becomes more concentrated (thereby darker).

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