Transcript HEAT STRESS

HEAT STRESS
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Heat Sources
Prepared by Paul Young
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Temperature
Humidity
Radiant Heat
Air Velocity
All of these have an effect on the human
body and the amount of stress that is
imposed.
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Skin Temperature
Prepared by Paul Young
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The body reacts to external temperature by
circulating blood to the skin. This increases
epidermal temperature and allows the body
to give off excess heat through the skin.
If the muscles are being used for physical
labor, less blood is available to flow to the
skin and give off heat.
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Perspiration
Prepared by Paul Young
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“Men sweat, women perspire, ladies merely
glow,” or so said a southern belle in a time
of extreme stress.
Sweating is another mechanism the body
uses to regulate internal temperature.
This is effective only if the humidity level is
low enough to permit evaporation, and if
lost fluids and salts are replaced properly.
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Effects of heat
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If the body cannot shed excess heat, it stores the heat internally.
As the body’s core temperature rises, there is an increase in heart rate
and other effects may occur, depending on temperature, physical
activity rate, humidity, etc.
As core temperature increases, individuals may experience:
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Lost concentration
Difficulty focusing on tasks
Irritability
Sickness, vomiting
Loss of desire to drink fluids
Fainting
Unconsciousness
Death
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HEAT INDEX
Prepared by Paul Young
Relative
Humidity
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Air Temperature
70
75
80
85
90
95
100 105 110
Apparent Air Temperature (Degrees Fahrenheit)
64
69
73
78
83
87
91
95
99
65
70
75
80
85
90
95
100 105
66
72
77
82
87
93
99
105 112
67
73
78
84
90
96
104 113 123
68
74
79
86
93
101 110 122 137
69
75
81
88
96
107 120 135 150
70
76
82
90
100 114 132 149
70
77
85
93
106 124 144
71
78
86
97
113 136 157
71
79
88
102 122 150 170
72
80
91
108 133 166
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Calculating Heat Index
Prepared by Paul Young
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Check the weather forecast:
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On the chart:
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Find today’s forecast high temperature
Find today’s expected humidity.
Temperature is across the top of the chart
Humidity is down the left side.
Cross the two values to find today’s apparent temperature.
Remember that these values are for shaded areas with
light wind conditions. Exposure to full sun will typically
increase these values by 15°. Working on hot asphalt will
also add 10°. Strong winds, especially hot, dry winds, also
increase hazards because of the drying effect on the skin.
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Dangers related to heat stress
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Heat Index 90 to 100 degrees:
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Heat Index 105 to 129 degrees
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Sun stroke, heat cramps and heat exhaustion are
all possible with prolonged exposure and
physical activity.
Sun stroke, heat cramps and heat exhaustion are
all likely.
Heat stroke is possible with prolonged exposure
and physical activity.
Heat Index 130 and above
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Heat stroke is imminent.
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Heat Exhaustion
Prepared by Paul Young
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Symptoms:
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Headaches; dizziness; weakness; mood changes; upset stomach;
vomiting; fainting; pale, clammy skin.
What to do:
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Act immediately. If not treated, heat exhaustion can quickly become
heat stroke.
Move the victim to a cool, shaded area. Don’t leave the victim alone.
If symptoms include dizziness or lightheadedness, lay the victim on
his or her back and raise the feet 6 to 8 inches. If symptoms include
nausea, lay the victim on his or her side.
Loosen or remove heavy clothing.
Have the victim drink a cup of cool water every 15 minutes.
Cool the victim by fanning or spraying
If the there are no signs of recovery after 15 minutes, call 911.
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Heat Stroke
Prepared by Paul Young
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Symptoms:
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Dry, pale skin with no sweating; hot, red skin that looks sunburned;
mood changes; seizures or fits; unconsciousness with no response.
What to do:
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Call 911 immediately.
Move the victim to a cool, shaded area and lay the person
on his or her back.
Loosen and remove any heavy clothing.
Have the person drink a cup of cool water every 15 minutes
(if conscious).
Cool the body by fanning or spraying with a cool water mist, damp
cloths or a wet sheet.
Place ice packs under the armpits and in the groin.
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Electrolytes
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Electrolytes can take two forms:
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Simple inorganic salts of sodium, magnesium,
potassium or calcium.
Complex organic molecules.
Electrolytes flow through muscle cells to
help maintain the normal cell function.
Electrolytes are lost through perspiration
and urination, and this depletes muscle
cells and weakens the muscle tissue.
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Fluid intake
Prepared by Paul Young
While it is important to replace body fluids
through drinking adequate quantities of
cool water, this does not replace those
valuable electrolytes.
 Water is still “nature’s perfect drink”, but
studies have shown that electrolyte
replacement products are absorbed
NINETY-EIGHT PERCENT {98%}
faster in the first minute after intake.
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Thirst
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While involved in physical activity, especially as
the temperature increases, most people
experience the sensation of thirst, and drink
water or other fluids to offset this sensation.
As heat stress increases, many people lose the
sensation of being thirsty, and so they don’t
replace the lost fluids, leading to dehydration
and the other harmful effects of heat stress.
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Types of Fluid
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Fluids that help quench thirst:
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Water
Sports drinks like Gatorade
Electrolyte replacement drinks
Fluids that DON’T help quench thirst
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Carbonated drinks (soda pop)
Caffeinated drinks (soda pop, coffee, tea)
Alcoholic drinks (beer, wine)
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Taste
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Taste has a marked effect on how employees
help prevent dehydration.
Not too long ago, employees exposed to high
levels of work-related heat were required to drink
salted fruit juices and other poor tasting drinks.
Modern electrolyte replacement fluids have a
taste that many people prefer to water.
If people prefer the taste, they will be more likely
to drink the fluid.
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The Buddy System
Prepared by Paul Young
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As in many other work-related hazardous
situations, it’s important that we look out for
ourselves and each other:
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Always be aware of your own thirst. Drink when you
feel thirsty. Working in direct sun on a hot day, you
need about a quart of fluid every hour to replace what
you lose through perspiration, etc.
Watch your crew mates. If you see any signs of heat
stress, encourage the team member to drink water or
electrolyte replacement fluids.
Notify your crew boss if you see a fellow worker
exhibiting signs of heat stress.