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Occupational heat stress and occupational health services
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Occupational Heat Stress& Occupational Health Services
By Dr Zahid Khan
Senior Lecturer King Faisal University, Saudi Arabia
Heat Stress
Heat StressTypes of Heat Transfer
Conduction. Convection. Radiation. Evaporation.
Heat Stress
Heat Stress Convection
Heat Stress Radiation
Heat Stress Normal Body Cooling The average 160 lb. adult has approx. 10 pints
(5 quarts) of blood and approx. 60,000 miles of plumbing.
When the body core temperature rises, blood is pumped to the skin to dissipate heat.
Sweating increases (evap cooling). Heart rate increases to speed up the flow of
blood to the skin.
Heat Stress If everything is working correctly, the excess heat will
dissipate and the core temp. will drop and stabilize. Primary cooling of the body is by radiation. Secondary is by evaporation (sweating).
Heat Stress Acclamation
Heat StressRisk Factors
Age- young children and the elderly & over 40 years of age.
Overweight or obese. Poor health. Coronary problems. Poor diet High Body fat
Risk Factors Medication & use of
Recreational drugs Use of alcohol. High blood pressure. Fever. Sleep deprivation. Dehydration prior to activity
Manifestations of Heat Stress Heat fatigue Heat rashes Heat cramps Heat collapse
Heat Exhaustion Heat stroke
Heat Fatigue Lack of adaptation to environment causes heat fatigue. S/S include impaired functioning of mental and
sensorimotor systems. No treatment available except to remove heat stress
before serious problems arise.
Heat rashes
Heat Rashes
The most common problem in hot work environment. It is manifested as red papules and usually appears in areas where
the clothing is restrictive. As sweating increases these papules give rise to 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.
Heat cramps
Painful muscle spasms that occur when a person drinks large amounts of water but fails to replace the body’s salt loss
– Usually controlled by drinking fluids that contain electrolyte replacements
Heat Exhaustion Some Symptoms of Heat Exhaustion
Intense thirst Fatigue Weakness Dehydration Moist, clammy skin Pale or flushed complexion Body temp normal or slightly higher
Typically treated by resting in a cool place and replacing fluids and minerals
Heat collapse Blood pools in the extremities in case of heat collapse causing
decreased oxygen supply to brain. 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.
If heat cramps or heat exhaustion is not properly treated, the
condition can quickly escalate into a HEAT STROKE
Body will no longer be able to cool itself
Temperatures can rise dangerously high resulting in
brain damage or death
Heat Stroke
Hot, dry, flushed skin
Very small pupils Extremely high
body temperature (106o or higher)
Mental confusion, convulsions or coma
Symptoms of a Heat Stroke
What does the "heat index" mean The heat index tells you how hot it feels outside in the
shade. It is not the same as the outside temperature. The heat index is a measurement of how hot it feels when relative humidity is combined with the effects of the air temperature. When you are standing in full sunshine, the heat index value is even higher. A heat index of 90° or above is dangerous.
How can I prevent heat illness?
When the heat index is high, stay indoors in air-conditioned areas when possible. If you must go outside, take the following precautions:
Wear lightweight, light-colored, loose-fitting clothes. Protect yourself from the sun by wearing a hat or using an umbrella. Use sunscreen with a sun protection factor (SPF) of 15 or more.
(cont.) Drink plenty of water before starting an outdoor activity. Drink fewer
beverages that contain caffeine such as tea and coffee & Alcohol etc. Schedule vigorous outdoor activities before 10 am and after 6 pm during off
days. Take frequent breaks during outdoor activities. Drink water or other fluids
every 15 to 20 minutes, even if you don't feel thirsty. If you have clear, pale urine, you are probably drinking enough fluids.
If you have a chronic medical problem, ask your doctor about how to deal with the heat, about drinking extra fluids and about your medicines.
What should I do after having heat exhaustion or heatstroke?
Having heat exhaustion or heatstroke makes you more sensitive to hot conditions for about a week afterwards. Be especially careful not to exercise too hard, and avoid hot weather. Ask your doctor to tell you when it is safe to return to your normal activities.
Any Questions !!!!!
•Thank You