HEAT STRESS

AUGUST 2009

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Working in the Heat

If you work outside you may be at increased risk for heat related illness. The combination of heat

and humidity can be a serious health threat during the summer months.

Heat stress is caused when our core body temperature exceeds the body’s capacity to maintain body temperature at normal levels.

Untreated, heat stress can create numerous serious health conditions or even death.

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Heat Stress – Risk Factors

Insufficient water intake – #1 factor leading to heat related illnesses – drink plenty of water – don’t wait until thirsty

High temperature – heat flows from warmer objects to cooler objects; higher temperature = higher risk

High humidity – reduces the rate of sweat evaporation (which is how the body cools down)

Limited air movement – slows the evaporation (cooling) process Poor physical condition – may affect how well a person can

adopt to and tolerate hot & humid work environments Acclimation – our bodies adapt to the environment - basically

getting “used to” the heat.  After a period of acclimatization, a worker performing the same activity will sweat earlier and more efficiently (causing better evaporative cooling) - more easily able to maintain normal body temperatures. 

Improper clothing – the type of clothing you wear may affect the amount of heat your body absorbs and retains

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Heat Related Health Issues

Heat Rash - occurs in hot, humid environments where sweat can't easily evaporate from the skin.  • The procedures to prevent or minimize this condition is to

rest frequently in cool places - bathe regularly & thoroughly dry the skin

Heat Exhaustion - is a state brought on by the loss of fluids lost during excessive sweating.  • Individuals with heat exhaustion still sweat, but they

experience extreme weakness and may even collapse• They may experience nausea and headache.  Their skin is

clammy and moist, their complexion is usually pale and the body temperature is usually normal or slightly higher 

• Treat the employee by taking them to a cool place, applying cool compresses, elevating the feet and giving plenty of fluids

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Heat Related Health Issues

Heat Stroke - is a severe medical emergency which could result in death – call 911.  The body’s failure to regulate its own core temperature (loss of sweating) can lead to mental confusion, loss of consciousness, and death.

• An individual suffering from heat stroke will have hot and dry skin, their pulse will be high and their blood pressure will fall 

• This condition must be treated by immediately cooling the victim's body with water or wrapping them in cool wet sheets.  Immediately seek medical attention – call 911

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Preventing Heat Stress

Drink Fluids - Fluid intake must be maintained throughout the course of the work day. Start drinking water before work. Do not rely on thirst as an indicator of dehydration because your body loses water faster than you realize. • You are expected to bring your own water supply to

drink throughout the work day; landscaping crews will also have a 5-gallon water cooler on-site

• Avoid alcohol because it is a diuretic, which increases dehydration and can interfere with heat loss

• Avoid drinks with caffeine and large amounts of sugar

Acclimation - Accustom yourself to the weather prior to long durations of physical activity. Gradually build up to heavy work.

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Preventing Heat Stress

Plan the Work / Rest Periods – Pace your work activities at a slower rate during high temperatures.• Schedule heavy work during the coolest parts of day;

get an early start (6 AM)• Take more breaks in extreme heat and humidity

(5-7 minute breaks every hour) • Don’t over-exert - take breaks in the shade or a cool

area whenever possible

Proper Diet – Eat light and stay away from heavy foods. They increase metabolic heat production and also increase water loss. Eat smaller, well-balanced meals more often.

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Preventing Heat Stress

Dress Light – Lightweight, light-colored clothing reflects heat and sunlight and helps your body maintain normal temperatures. • Wear light-colored, loose-fitting, breathable clothing

such as cotton. Avoid non-breathing synthetic clothing.

Stay Fit and Healthy

Be Aware - Recognize the sign & symptoms of heat stress and report them to your Supervisor immediately.

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Heat Index

There are a number of heat stress indexes available to determine the degree of hazard, although no single one is universally used.

For predicting weather related stress, the National Weather Service uses a heat index that calculates an apparent temperature based on temperature and humidity.

This widely used measure can serve as a practical indicator in certain occupational settings.

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Heat Index

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Heat Index

Heat Index Danger Category Possible Heat Disorders

130°F or higher Extreme DangerHeat stroke highly likely with continued exposure.

105° - 130°F DangerHeat stroke, heat cramps or heat exhaustion likely; heatstroke possible with prolonged exposure and/or physical activity.

90° - 105°F Extreme CautionHeat stroke, heat cramps and heat exhaustion possible with prolonged exposure and/or physical activity.

80° - 90°F CautionFatigue possible with prolonged exposure and/or physical activity.

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QUESTIONS ??

Please feel free to ask any questions about the material we’ve covered…