Thermal Stressors - Bowen Flashcards
What is metabolic heat?
Metabolic heat is the energy generated while the body is being active
What is external work?
The physical work produced by the body. it is the work performed by moving a mass from point A to point B
What is a psychrometric chart?
The psychrometric chart provides a graphical relationship of water vapor pressure, dry bulb temperature, wet bulb temperature, relative humidity, and dew point.
What heat illnesses can result from overexposure to heat?
Heat stroke, heat hyperpyrexia, heat exhaustion, heats syncope, heat cramps, heat rash, and heat fatigue
What is heat stroke?
Emergency medical condition. The most severe of the heat illnesses. It occurs when the body fails to regulate body temperature.
- Skin is hot and dry.
- Confused behavior.
- Loss of consciousness.
- Convulsions.
- Medical emergency
What is heat exhaustion?
It is excessive loss of water through sweating.
- Fatigue.
- Nausea.
- Headache or giddiness.
- Cold, clammy skin.
How do you treat heat exhaustion?
Get the person to a cooler location and replace body fluids
What is heat syncope?
Non-acclimitized person standing in the heat faint. blood flow reduced to the brain.
What is the treatment for heat syncope?
Remove victim to cooler location and have them lie down
What are heat cramps?
- Painful muscle cramps during or following work in hot environments
- Body salts lost through sweating
How do you treat heat cramps?
Replace fluids containing appropriate salts
What is a heat rash?
- Small blister like eruptions during heat exposure
- Plugged sweat glands swell
How do you treat heat rash?
Keep skin clean and dry
What is heat fatigue?
- Reduced performance on workers
- Non-acclimated workers are most susceptible
What are ways to prevent heat illness from occurring?
- Drink plenty of fluids during hot weather.
- Take frequent breaks as necessary.
- Personal protective equipment.
- Engineering controls.
- Acclimization
What engineering controls can help prevent Heat illness?
- Air conditioning.
- Mists in the air.
- Fans moving air, only if the ambient temperature is below body temperature (cooling fan)
- Cooled seats or benches for rest breaks
- Use of mechanical equipment to reduce manual work (such as conveyors and forklifts).
What are the different types of cold illnesses?
- Body combats called temperatures through shivering and circulation adjustments.
- Trench foot.
- Chilblains.
- Cold urticaria.
- Frostbite.
- Hypothermia.
What is Trench foot?
Trench foot occurs after several days of exposure to cold (not freezing) temperatures and moist skin.
- Vasoconstriction in feet and legs.
- Pale appearance and numbness.
What is cold urticaria?
Urticaria = hives
Cold can cause histamine releases in body tissue.
- Produces itchy, red blotches.
- Only occurs in some people.
- May cause vomiting, rapid heartbeat, and swelling of breathing passages.
What is frostbite?
- Must occur at temperatures below 0°C / 32°F
- Freezing of body tissue.
- White, or grayish yellow skin.
- Damage dependent on depth of freezing.
What is hypothermia?
Defined as having a core body temperature less than 95°F / 35°C
Symptoms:
- Shivering initially occurs.
- Numbness.
- Disorientation.
- Confusion.
- Amnesia.
- Impaired judgment.
What are three ways to prevent cold illness?
- Provide heat source where feasible.
- Minimize exposure time.
- Protective clothing.
What is the body’s core temperature that should be maintained?
37C / 98.6 F
At what temperature does tissue freezing occur at?
Frostbite occurs when tissue temperature decreases below 32F / 0C
At what temperature should machine controls be designed for operation with gloved hands?
Less than 16°C / 60.8°F
Primary objective for heat stress TLV?
- Maintain body core temperature within +1C of the normal (37C, 98.6F) temperature for the average person.
The TLV tries to prevent core body temperature from dropping below..
36°C / 96.8°F
Personal risk factors for heat strain?
- Prior heat stroke
- Repeated heat exhaustion
- Cardiac or kidney disease
- Pregnancy
- Obesity (less fit people are more susceptible to heat stress)
- Older age (elderly more susceptible to heat stress)
- Certain medications
- Alcohol use
Difference between heat stress and heat strain?
Heat stress it the net heat load a worker may be exposed to, heat strain is the body’s physiological response to heat stress.
What is acclimatization?
The gradual physiological adaptation that improves an individual’s ability to tolerate heat stress.
TLV clothing adjustment factors of 0
- Work clothes (long sleeve shirt and pants)
- Cloth (woven material) coveralls
Clothing factor for limited use vapor barrier coveralls?
11
Clothing factor for Polyolefin coveralls?
1
Clothing factor for double-layered woven clothing?
3
Clothing factor for SMS polypropylene coveralls?
0.5
Sustained heart rate should not be in excess of
180 bpm - person’s age
Recovery heart rate after one minute of peak work effort should not be greater than
120 bpm
Body core temperature should not be greater than…
- 38.5°C (101.3°F) for acclimatized workers
- 38°C (100.4°F) for un-acclimatized workers
What physiological symptoms can indicate excessive heat stain?
-Sustained (several minutes) heart rate is in excess of 180 bpm minus the individual’s age in yeras (180- age) for individuals with assessed normal cardiac performance
- Body core temperature is greater than 38.5 C (101.3F) for medically selected and acclimatized personnel; or greater than 38C (100.4F) in unselected, unacclimatized workers
- Recovery heart rate at one minute after a peak work effort is greater than 120; or
- There are symptoms of sudden and severe fatigue, nausea, dizziness, or lightheadedness
What is convection
Heat transfer between the skin and air
Think convection oven
How does the body lose heat
- Sweating (evaporation)
- Increase heart rate and blood flow
- Vasodilation - body pumps more blood to surface to lower internal body temperature (Radiate heat out)
- Controlling loss of H2O and salt via ADH and aldosterone
What is conduction
Physical contact with a surface and a transfer of heat takes place from the hotter object to the cooler object
Think electrical conductor
How does clothing impact heat exchange?
It affects convective and evaporative heat exchange
What environmental factors affect heat stress?
- Air movement
- Temperature
- Radiant heat loss
Radiant heat stress controls
- Provide shields between the heat source and the people
- Use reflective screens
- Use reflective clothing
- Cover exposed parts of the bodyA
What are the three types of heat transfer?
- Conduction
- Convection
- Radiation
