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 !!!!!

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