HEAT STRESS INFORMATION AND PREVENTION

Heat Stress Information & Prevention

High temperatures place stress on our bodies. When the body's cooling system has to work too hard to reduce excessive heat, it can strain itself. This physical strain, in combination with other related factors such as work, loss of fluids or fatigue, could lead to heat disorders, temporary or permanent disability, and, even death.

WHO IS "AT RISK"?

Anyone who lives, works or vacations in warm or seasonally warm climates or works in hot, humid places can be affected by heat stress, even when they are young and healthy. Typical victims of heat disorders include, but are not limited to, the following:

1. Athletes (particularly runners) ,
2. Farmers,
3. Cooks in hot, humid kitchens,
4. Laborers,
5. Boiler room workers,
6. Landscape maintenance crews.

HAZARDS OF HEAT STRESS

In addition to the significant medical problems associated with heat disorders, there is also a higher frequency of accidents in hot environments. Direct causes of accidents associated to heat include:

1. Fogged glasses,
2. Sweat in the eyes,
3. Slippery hands,
4. Dizziness or fainting.

Indirect causes of accidents include:

1. Physical discomfort,
2. Irritability and anger,
3. Poor judgment,
4. Diverting attention from the job,
5. Slower mental and physical job reactions (response times).

COPING WITH HAZARDS

Heat disorders are preventable with proper planning, supervision and training. Steps that you can take to cope with the hazards of heat stress include:

1. Understand the effects of heat stress;
2. Know the symptoms and treatment for heat disorders;
3. Take personal precautions against heat disorders.

HOW YOUR BODY HANDLES HEAT

To understand the effects of heat stress you need to know how your body handles heat.

CONDITIONS AFFECTING BODY HEAT

Your body always generates internal heat. The amount of heat that stays in your body depends on several factor that include:

1. Surroundings (temperature and humidity),
2. Level of physical activity,
3. Type of work,
4. Time spent working,
5. Recovery time between work periods (work rests).

HEAT GAIN OR LOSS

Your body has a thermoregulation (heat control) mechanism that attempts to maintain inner body (core) temperature at a constant 98.6 degrees Fahrenheit. Your body gains or loses heat in four ways:

1. Radiation - transfers heat to or from surrounding objects that are not in direct contact with the body;
2. Convection - transfers body heat to or from air moving over the skin;
3. Conduction - is direct contact with objects that are colder or warmer than the body;
4. Evaporation - causes cooling when air absorbs body moisture from the lungs or skin.

The amount and speed of heat transfer (gain or loss) depends on a number of factors:

1. Temperature of the air and surrounding objects
2. Air movement (wind or fans)
3. Humidity (amount of water vapor in the air).

EFFECTS OF HEAT STRESS

When resting, your body loses 75% of its heat through conduction, convection or radiation from the blood vessels just below the skin surface. As your internal body heat rises due to work or high temperatures, surface blood vessels get bigger and the pulse rate goes up. This action puts a strain on your heart and circulatory system.

YOUR BODY'S COOLING SYSTEM

When more blood is pumped close to your skin for cooling, less blood goes to your brain. Bending, squatting or standing up suddenly can result in dizziness or a momentary blackout which can cause secondary injuries or accidents at a job site. If the temperature of the air and surrounding objects in your work area rises above body temperatures, then conduction, convection and radiation cause the body to gain heat instead of losing it. The evaporation of sweat becomes the body's most important - and sometimes only - cooling method.

Sweating can also make things worse by causing you to lose body fluids and minerals. Most people will lose about a quart of sweat an hour while working in extreme heat. This puts even more strain on the circulatory system since it actually lowers the amount of blood (reduces blood volume)in your body. Just because you're sweating, you may not be getting rid of heat, since sweat must evaporate to cool your body. Normally, the faster the air moves over the body, the more sweat evaporates. However, if the air is too full of water vapor to absorb any more moisture, you can work directly in front of a fan and still not lose any heat.

Finally, if your body's natural defense mechanisms against heat are pushed beyond their limits, they may simply shut down, leading to uncontrolled and explosive rise in body temperature that can cause heat stroke, permanent damage to the central nervous system or death. This situation is a critical medical emergency.

MINOR HEAT STRESS DISORDERS

SUNBURN

Sunburn is often overlooked as a danger when working outdoors in direct sunlight. Besides the discomfort of the burn itself, sunburn can prevent your body from eliminating heat efficiently and can contribute to one of the more serious and dangerous heat disorders.

CAUSE
Exposure of unprotected skin to ultraviolet light.

SYMPTOMS

1. First degree - red, painful skin
2. Second degree - blistering and/or peeling
3. Third degree - severe blistering, bleeding and deep tissue destruction.

TREATMENT

1. Skin lotions,
2. Topical anesthetics,
3. Staying in shaded (protected) area.

PREVENTION

1. Limit exposure on bare skin,
2. Frequent and liberal use of sun screen,
3. Never use tanning oils or lotions!

HEAT RASH

Heat rash, also known as prickly heat, is another minor annoyance that can lower the body's ability or regulate heat.

CAUSE

1. Hot, humid environment
2. Sweat ducts become plugged
3. Sweat won't evaporate
4. Skin stays wet most of the time.

SYMPTOMS

1. Red rash
2. Itching.

TREATMENT

1. Lotion to relieve the symptoms. Ointments may block sweat ducts and exacerbate the problem.

PREVENTION

1. Bathe regularly
2. Keep skin clean and dry.

MAJOR HEAT EXPOSURE RELATED DISORDERS

HEAT CRAMPS

Heat cramps are always a danger signal since they may occur alone or be combined with one of the other major heat exposure disorders. These are painful - sometimes severe - cramps of the muscles used while working, such as the arms, legs or stomach. They often occur later, when relaxing after work.

CAUSE

1. Sweating heavily
2. Replacing water without minerals.

SYMPTOMS

1. Sudden onset
2. Hot, moist skin
3. Normal pulse
4. Normal to slightly high body temperature.

PREVENTION

1. Move into shade or improvise shade
2. Loosen clothing
3. Drink lightly salted liquids (0.1% saline solution)
4. Wait to see if symptoms go away
5. Seek medical assistance if the cramps persist.

HEAT EXHAUSTION

Heat exhaustion occurs when the body's heat regulating mechanism is overactive but hasn't broken down completely. The victim may also be having heat cramps, and there is a high risk that the victim will continue on to a state of heat stroke. This disorder also causes special risk to older persons or those with coronary artery disease or emphysema.

CAUSE

1. Surface blood vessels that enlarged to cool the blood collapse from loss of body fluids and minerals.

SYMPTOMS

1. 1. Heavy sweating
2. 2. Intense thirst from dehydration
3. 3. Cool, moist skin (clammy and pale)
4. 4. Weak and rapid pulse (120 to 200 beats per minute)
5. 5. Low to normal blood pressure (>120/80)
6. 6. Fatigue, weakness or loss of coordination.

OTHER SYMPTOMS OF HEAT EXHAUSTION

1. Anxiety or agitation
2. Clouded senses, impaired judgment or fainting
3. Tingling in hands and feet and/or headache
4. Loss of appetite, nausea or vomiting
5. Hyperventilation (rapid breathing or panting)
6. Oral temperature slightly low (if hyperventilating).

FIRST-AID TREATMENT
When and you suspect a coworker is experiencing heat exhaustion, you will need to do the following:

1. Move victim into the shade (or improvise shade)
2. Loosen or remove clothing and boots
3. Cool the victim as fast as possible
4. Fan the victim
5. If necessary, pour water on the victim
6. Elevate the victims legs and massage limbs
7. Have the victim drink water - with salt - if available. Sport drinks are best as they provide the proper balance of salts lost through sweat. (Note: Never give liquid unless the victim is conscious.)
8. Stay with the victim until medical help arrives

Victims of heat exhaustion must be examined by a qualified medical practitioner and should not participate in strenuous activity for the rest of the day. Bed rest and restoration of body water and salt usually are all the treatment needed.

HEAT STROKE

Heat stroke is a MEDICAL EMERGENCY requiring IMMEDIATE MEDICAL ATTENTION! It is considered a catastrophic illness and has a high death rate. Outwardly, it may first progress through the symptoms of heat cramps and/or heat exhaustion, with a dramatically sudden onset of heat stroke symptoms followed by rapid deterioration of the victim.

CAUSE

When the body depletes its salt and water supplies, sweating stops and heat loss by evaporation of sweat is blocked. The victim's body temperature soars to fatal levels. Heat stroke occurs more readily when the body has suffered a previous heat disorder.

EARLY SYMPTOMS

1. High body temperature - above 103 degrees F
2. Absence of sweating - in most cases
3. Hot, red or flushed, dry skin
4. Rapid pulse
5. Difficult breathing
6. Constricted pupils
7. High blood pressure
8. Headache or dizziness
9. Confusion or delirium
10. Bizarre behavior
11. Weakness
12. Nausea or vomiting.

ADVANCED SYMPTOMS

1. Seizure or convulsions
2. Collapse
3. Loss of consciousness
4. Deep coma
5. No detectable pulse
6. Body temperature over 108 degrees F.

FIRST-AID TREATMENT

The most important step is prompt recognition of heat stroke symptoms and immediate treatment. Follow the same steps as for heat exhaustion, but start the cooling process without delay.

1. You must lower the victim's body temperature as fast as possible.
2. Immerse the victim in water.
3. Massage their body with ice.
4. Don't give liquids to unconscious victims.
5. Call an ambulance and evacuate the victim to a hospital.

CONTROLLING HEAT STRESS

You owe it to yourself and your fellow workers to recognize the signs of heat stress and know the proper first-aid measures. But you can also take precautions to prevent heat disorders including:

1. Acclimatization
2. Proper work procedures
3. Food and water intake

ACCLIMATIZATION

If you can't control temperature or humidity in your workplace, you must become acclimatized to it. Acclimatization is the ability to perform a maximum amount of strenuous work in the heat by gradually getting yourself used to the climate in which you must work.

First, get yourself into good physical condition. Physical work in the heat is necessary for full acclimatization, but should consist of increasingly longer work periods each day, alternating with rest or lighter work.

Some workers reach full acclimatization within a week, while others take longer. If you go on vacation, remember, you will start losing your resistance to heat after one week and you'll lose it completely in a month's time.

WORK PROCEDURES

Another important method for reducing the ill effects of heat stress is to follow scheduled work/rest cycles that keep any individual from overdoing it. In this case, rest means minimal activity, not stopping work completely. Workers may alternate light and heavy work, indoor and outdoor work, etc. Duties may also be rotated among several workers to protect them from heat, changing work shifts to avoid excessive afternoon heat for outdoor workers, and workload can be adjusted based on body size or physical strength.

FOOD AND WATER INTAKE

Most people don't realize that hot food adds directly to body heat. Heavy meals reduce your ability to get rid of heat because they redirect blood flow to your digestive tract instead of your skin surface. Be sure your noon meal is light and cool, then try to rest for a while right after eating. Plan your heaviest meal of the day for evening after the workday is over.

The most important step you can take is to replenish water and salt used up by your body's cooling mechanisms. Fluid intake should equal fluid loss throughout the day. Be sure you have enough cool drinking water at your job site and drink 5 to 7 ounces of water every 15 to 20 minutes, even if you don't feel thirsty. Water temperature should be 50 to 60 degrees F for best absorption by the body.

Consuming drinks designed to replace blood fluids and electrolytes is okay, but NEVER drink alcoholic beverages in an attempt to replace fluids since alcohol dehydrates the body.

Except when treating heat disorders, salt supplements are not recommended, since too much salt can cause higher body temperature, increased thirst and nausea. The normal diet usually has enough salt in it, but if you sweat continuously or repeatedly, you may use extra salt at the table. Salt tablets are considered harmful because the salt doesn't enter your system as fast as water or other fluids.

If you use salt for treating heat disorders, make a 0.1% saline solution by adding , one teaspoon of table salt per quart of water. If only salt tablets are available, crush two of them completely so they will dissolve quickly to make the solution.

FACTORS AFFECTING HEAT DISORDERS

Some of the factors affecting heat disorders are things you can control, such as the amount of salt you eat, while others are not. For your safety, a summary of physical conditions that can hurt your body's natural ability to withstand high temperatures follows:

1. Dehydration (water loss);
2. Diarrhea and anti-diarrheal medications;
3. Exposure to high temperatures at night;
4. Fatigue (it takes work to lose heat);
5. Improper work procedures;
6. Lack of acclimatization;
7. Loss of sleep;
8. Obesity;
9. Age (over 40 years of age);
10. Medications that inhibit sweating, such as antihistamines, cold remedies, diuretics, tranquilizers, etc.;
11. Previous occurrence of heat stroke;
12. Poor physical conditioning;
13. Recent immunization (they can give you a fever);
14. Recent drug or alcohol use (within 24 hours);
15. Skin trauma (heat rash or sunburn);
16. Wrong type of clothing - tight clothes restrict circulation and keep air from flowing over the skin.

For additional information consult your private medical provider.

Note: Heat stroke is even more deadly because its true symptoms can be masked. For example, in heat stroke caused by exertion, the victim may still be sweating. Also, cool skin may hide a high core body temperature. On the job, collapse from heat stroke is often mistaken for heart attack or head injury.