Heat Stress

UW-Eau ClaireFacilities Management

By: Chaizong Lor, FM Safety Coordinator

Heat Stress

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

Heat Stress

• What is Heat Stress?– The combination of environmental and

physical work factors that constitute the total heat load imposed on your body’s cooling system.

Heat Stress• Body’s 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.

Heat Stress• Body’s 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.

Heat Stress

Heat Stress

– Mechanisms for heat loss/transfer• Evaporation

– The body transfers water vapor to the skin through pores and sweat glands

• Background – Heat Exchange

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:

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

                              

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

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

Heat Stress• Heat Stress Hazards Cont.

– Heat Exhaustion• Cause

– Dehydration causes blood volume to decrease– Inadequate salt and water intake causes a person’s body’s

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

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

• 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

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

Heat Stress

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.

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.

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.

Any Questions

??Revision Dated: July 22nd, 2014