Occupational heat stress and occupational health services

1. Occupational Heat Stress&
Occupational Health Services
By Dr Zahid Khan
Senior Lecturer King Faisal
University, Saudi Arabia

2. Heat Stress

3. Heat Stress
Types of Heat Transfer
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Conduction.
Convection.
Radiation.
Evaporation.

4. Heat Stress

5. Heat Stress
Convection

6. Heat Stress
Radiation

7. Heat Stress
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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.

8. Heat Stress
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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).

9. Heat Stress
Acclamation

10. Heat Stress
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Risk Factors
Age- young children and the
elderly & over 40 years of
age.
Overweight or obese.
Poor health.
Coronary problems.
Poor diet
High Body fat
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Risk Factors
Medication & use of
Recreational drugs
Use of alcohol.
High blood pressure.
Fever.
Sleep deprivation.
Dehydration prior to activity

11. Manifestations of Heat Stress
Heat fatigue
 Heat rashes
 Heat cramps
 Heat collapse
 Heat Exhaustion
 Heat stroke
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12. 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.
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13. Heat rashes

14. Heat Rashes
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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.

15. Heat cramps
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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

16. Heat Exhaustion
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Some Symptoms of Heat Exhaustion
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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

17. Heat collapse
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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.

18. Heat Stroke
If heat cramps or heat exhaustion is not properly treated, the
condition can quickly escalate into a HEAT STROKE
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Body will no longer be able to
cool itself
Temperatures can rise
dangerously high resulting in
brain damage or death
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19. 
Symptoms of a Heat Stroke
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Hot, dry, flushed
skin
Very small pupils
Extremely high
body temperature
(106o or higher)
Mental confusion,
convulsions or
coma

20. What does the "heat index" mean
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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.

21. How can I prevent heat illness?
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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.

22. (cont.)
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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.

23. What should I do after having heat exhaustion or
heatstroke?
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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.

24. Any Questions !!!!!
•Thank You