Take care of yourself this summer

Heat Stress*

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. The body temperature of man is controlled at a constant 37 degrees Centigrade by the thermoregulatory centre in the brain. Heat is produced by cellular metabolism and lost through the skin by dilating of the superficial blood vessels (through conduction and radiation) and sweating. Some heat is also lost via the lungs through expired air. Sweating occurs when the temperature exceeds 32o C, and during exercise. Evaporation of sweat is an important mechanism in keeping the body temperature down.
Acclimatization
It is possible to minimize the adverse effects of hot environment by allowing time for your body to adapt. This adoption is almost completed in about 10 days but is lost quickly in about 2-3 days.

Heat Cramps
These are painful cramps that usually occur in the leg muscles after exercise or heavy work in hot weather. They often occur in fit young people who are well acclimatized. Cramps appear to be mostly caused by the lack of water replenishment. Because sweat is a hypotonic solution 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 DURING WORK IN HOT ENVIRONMENTS.

Under extreme conditions, such as working for 6 to 8 hours in heavy protective gear, a loss of sodium may occur and this lack of salt can also cause cramps. Research has shown that drinking commercially available carbohydrate-electrolyte replacement liquids is effective in treating this problem.

Heat Fatigue
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, 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.

Heat Exhaustion
This usually occurs in subjects who are not acclimatized and who undertake heavy exercise in hot conditions. It is commonly seen in troops who are quickly transported to a hot climate without prior acclimatization. Water and salt depletion is the cause: water and salt loss through sweating can be as high as 6 liters and 20 g per day respectively. Symptoms include headache, thirst, nausea, vertigo, giddiness, generalized fatigue, weakness, and syncope. Sweating usually continues. Low blood pressure and rapid pulse may be present and the body temperature can rise to as high as 39oC. This condition responds readily to prompt treatment but should be treated seriously both due to the danger of fainting and because its symptoms are similar to those of Heat Stroke which is a medical emergency.
Treatment

Workers suffering from heat exhaustion should be moved to cool environment and given oral fluid replacement. They should also be encouraged to get adequate rest. Medical advice should be sought. In severe cases, intravenous fluid replacement is required.

Heat Stroke
This is an acute, life threatening condition. The patient suffers from headache, nausea, vomiting, diarrhea and weakness. The primary signs and symptoms of heat stroke are confusion, irrational or aggressive behavior, loss of consciousness, convulsions, a lack of sweating (usually, but there may be profuse sweating), hot, dry skin, and an abnormally high body temperature, e.g., 41°C (105.8°F).

Heat stroke can occur under hot, humid conditions when there is no wind or air movement, even without work or exercise. Susceptible people include the una acclimatized and the elderly. Diabetes, drugs, and alcohol can make a person more susceptible to heat stroke.

If a person shows signs of possible heat stroke, professional medical treatment should be obtained immediately. The patient should be placed in a shady area and have their outer clothing removed. The skin should be wetted and air movement around the person should be increased (e.g. by fans) 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. This condition can be fatal and the outcome depends on the victim's physical fitness and the timing and effectiveness of first aid treatment.

REGARDLESS OF HOW MUCH THEY MAY PROTEST, 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.

*copied from QPNET