Heat Stress Safety Meeting Series

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Heat StressSafety Meeting Series
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What is it?

• Heat stress is the buildup in the body of heat
  generated by the muscles during work and of heat
  coming from warm and hot environments.
• Heat illnesses result when the body is subjected
  to more heat than it can cope with.

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Why worry about it?

• Heat can kill!
• Work-related heat stroke fatalities
• 1990 student, second day collecting garbage
• 2001 bakery worker in Barrie
• According to Environment Canada on August 9, 2001
  outdoor temperature in Barrie is 33.4C, and
  humidity was 30 so the outdoor humidex was 36C
  and the outdoor WBGT was 24.8C
• If temperature in the bakery was estimated to be
  52C and if the humidity inside was 10, then
  humidex would have been 54C for the workplace

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True or False?

• High internal temperature makes blood vessels
  expand and the heart rate quicken.
• A heat stroke can be fatal.
• Sweating cools the body.
• Operation of the bodys cooling system can result
  in
• Rashes
• Dizziness
• Swelling
• Fainting
• Death
• If you dont feel thirsty, there is no need to
  drink water.
• As long as you drink a sufficient amount, the
  timing of it doesnt matter.

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Physiology of Heat Stress

• During both rest and activity, the human body
  tries to maintain an internal temperature of
• 37 C or 98.6 F.
• (/- 1 C or 1.8 F)

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Physiology of Heat Stress

• Hot weather, heat sources, and hard work raise
  the bodys core temperature.
• Heated blood is pumped to the skins surface,
  where body heat transfers to the environment, if
  cooler.
• If heat has to be shed faster, sweat carries it
  outside skin and evaporates to aid cooling.

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Physiology of Heat Stress

• During heavy work, a body can lose 1-2 liters of
  water per hour.
• After 2-3 hours of fluid loss, a person is likely
  to
• Lose endurance
• Become uncomfortable
• Feel hot
• Become thirsty

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Physiology of Heat Stress

• The longer a body sweats, the less blood there is
  to carry excess heat to skin or oxygen and
  nutrients to muscles.
• After 3 hours, a dehydrated worker may
  experience
• Headaches
• Muscle fatigue
• Loss of strength
• Loss of accuracy and dexterity
• Heat cramps
• Reduced alertness
• Nausea

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Physiology of Heat Stress

• Water is key to cooling body and combating heat
  stress.
• Without fluid replacement during an extended
  period of work, the body is at risk of
  exhaustion.
• Untreated heat exhaustion may lead to heat
  stroke.

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Health Effects

• When heat gain exceeds the ability of the body
  to compensate, heat illnesses can result
• Heat rash, other skin ailments
• Sunburn
• Heat cramps
• Fainting
• Heat exhaustion
• Heat stroke

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Everyones Different

• People come in many shapes and sizes and with
  different tolerances for heat.
• Personal factors affecting tolerance include
• Activity level (metabolic heat)
• Fluid intake and electrolyte replenishment
• Alcohol and drug use
• Acclimatization
• Age
• Physical fitness
• Body fat
• Diet

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Controlling Heat Exposure

• Acclimatization
• Engineering controls
• Administrative controls work practices
• P.P.E.

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Controlling Heat Exposure
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Hydration

• Fluid Replacement is extremely important!
• More than you want just to satisfy your thirst
• Sources of water are
• 1. Fluids - 1 cup or 8 oz 240 mL every 20 min
• 2. Foods - fruit veggies are 90 water
• Maximize the amount you drink by ensuring the
  water is not too cold, but not lukewarm

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Things You Can Check

• Look for typical heat strain symptoms feeling
  over-heated, fatigue, headache, nausea, weakness,
  dark concentrated urine, etc.
• Sweat that drips off your body no longer allows
  for cooling by evaporation thus, unless theres
  another medical reason for it, this is a sign
  that your body is heating up.
• Check your pulse heat stress is unlikely if your
  pulse rate is under 100 beats per minute after 1
  minute rest.