Heat Stress

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Heat Stress

• UW-EC
• Facilities Planning Management
• By Chou Lor

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Heat Stress

• Training Objectives
• Background Factors
• Heat Stress Hazards
• Heat Stress Control Measures
• Prevention of Heat Stress

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Heat Stress

• What is Heat Stress?
• The combination of environmental and physical
  work factors that constitute the total heat load
  imposed on your bodys cooling system.

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Heat Stress

• Bodys Cooling System
• Blood is pumped close to skin for cooling
  reducing blood going to the brain and rest of
  your body.
• As temperatures rise, surface blood vessels get
  bigger and pulse rate goes up.
• As temperatures rise your body gains heat instead
  of losing it.

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Heat Stress

• Bodys Cooling System Cont.
• Most people lose about a quart of sweat/hr in
  extreme heat.
• This adds a strain to your circulatory system
  which now has to lower the amount of blood in
  your body.

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Heat Stress
Mechanisms for heat loss/transfer
Evaporation
Radiant Heat
Convection
Conduction
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Heat Stress

• Mechanisms for heat loss/transfer
• Evaporation
• The body transfers water vapor to the skin
  through pores and sweat glands

• Background Heat Exchange

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Heat Stress

• Background Heat Exchange Cont.
• Mechanisms for heat loss/transfer
• Conduction
• The direct transfer of heat from skin to the
  surrounding air as the ambient temp rises
• Convection
• Air blowing over the skin e.g. use fan
• Radiation
• The transfer of heat to or from surrounding
  objects that are not in direct contact with the
  body

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Heat Stress

• Types of Heat Stress

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Heat Stress

• Heat Stress Hazards Cont.
• Heat Rash
• Cause
• Hot humid environment
• Skin is constantly wet from sweat
• Sweat gland ducts become plugged
• Signs Symptoms
• Painful or itchy skin
• Blister-like rash
• Treatment
• Keep skin clean and dry
• Stay cool with air conditioning
• Fans and cool showers
• Wear lightweight loose-fitting clothing
• Prevention
• Shower after working in hot environment
• Keep skin clean and dry

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Heat Stress

• Heat Stress Hazards Cont.
• Heat Fatigue
• Cause
• Lack of acclimatization
• Depletion of water and salt due to sweating
• Signs Symptoms
• Discomfort
• Feeling of weakness and tiredness
• Impaired performance of skilled tasks in heat
• Inability to concentrate
• Treatment
• No treatment necessary unless other signs of heat
  illness are present
• Prevention
• Acclimatization of workers for work in the heat

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Heat Stress

• Heat Stress Hazards
• Heat Cramps
• Cause
• Heavy sweating during hot work, drinking large
  amount of water without replacing salt loss
• Signs Symptoms
• Painful muscle spasms of arms, legs and stomach
• Usually occur after heavy sweating and may begin
  towards the end of the workday
• Treatment
• Drink water, move to a cool shaded area
• Spray the person with water and massage the cramp
• Adequate salt intake at meals, try eating more
  fruits
• Prevention
• Adequate salt intake with meals, and adequate
  water intake
• Drink fluids regularly

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Heat Stress

• Heat Stress Hazards Cont.
• Heat Exhaustion
• Cause
• Dehydration causes blood volume to decrease
• Inadequate salt and water intake causes a
  persons bodys cooling system to break down
• Signs Symptoms
• Fatigue, weakness, dizziness, faintness
• Nausea, headache, heavy sweating
• Low to normal blood pressure
• Treatment
• Move person to a cool shaded area
• Provide cool water to drink
• Fan and spray with cool water
• Prevention
• Acclimatize worker using a work rest
• Drink plenty of water

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Heat Stress

• Heat Stress Hazards Cont.
• Heat Stroke
• Cause
• Partial or complete failure of sweating mechanism
• Body cannot get rid of excess heat
• Sign Symptoms
• Hot dry skin, elevated body core temperature,
  confusion, loss of consciousness
• Fatal if treatment is delayed
• Treatment
• Medical emergency
• Move the victim to a cool shady area
• Remove excess clothing
• Spray the person with cool water
• Prevention
• Monitor workers in sustained work in severe heat
• Drink plenty of water
• Drink cool fluids that do not contain caffeine

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Heat Stress

• Heat Stress Control Measures
• Engineering Controls
• Reduction of Humidity
• Reduce the temperature and humidity through air
  conditioning
• Provide air-conditioned rest areas.
• Ventilation and Air Conditioning
• Use of air-circulating fans
• Better ventilation, to draw heat and steam away
  from work areas
• Shielding between workers and heat sources

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Heat Stress

• Heat Stress Control Measures
• Administrative Controls
• Changing the rate of work
• Schedule hot jobs to cooler times of the day.
• Increase the frequency and length of rest breaks
  if possible
• Encouraged employees to take a rest break should
  any sign of heat stress or heat disorder develop.
  
• Allow for slower-paced work during the hottest
  periods of the day
• Limiting duration of exposure time
• Rotate work activities

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Heat Stress

• Heat Stress Control Measures Cont.
• Protective Clothing
• Light summer clothing should be worn to allow
  free air movement and sweat evaporation.
• Outside, wear light-colored clothing.

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Heat Stress

• Prevention of Heat Stress
• Supervisor
• Identify all hot work environments under his/her
  authority
• Ensure that employees have been trained in hot
  working environments
• Train workers to recognize signs symptoms of
  heat stress disorders and be prepared to give
  first aid if necessary.
• Avoid placing employees in hot work environments
  for extended time periods. Realize individual
  employees vary in their tolerance to heat stress
  conditions.

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Heat Stress

• Prevention of Heat Stress
• Employees
• Learn to recognize the symptoms of heat stress.
  Change work location, taking adequate rest
  periods (in shade or cooler environment).
• Become familiar with the hazards associated with
  working in hot environments
• Use adequate fans for ventilation and cooling,
  especially when wearing personal protective
  equipment (PPE).
• Wear light colored, loose (unless working around
  equipment with moving parts) clothing.
• Keep shaded from direct heat where possible
  (e.g., wear a hat in direct sunlight).
• Drink plenty of water. In hot environments the
  body requires more water than it takes to satisfy
  thirst.

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