HEAT WAVE A NATIONAL PROBLEM
Heat kills by taxing the human body beyond its
abilities. In a normal year, about 175 Americans
succumb to the demands of summer heat. Among
the large continental family of natural hazards,
only the cold of winter-not lightning, hurricanes,
tornadoes, floods, or earthquakes-takes a greater
toll. In the 40-year period from 1936 through 1975,
nearly 20,000 people were killed in the United
States by the effects of heat and solar radiation.
In the disastrous heat wave of 1980, more than
1,250 people died.
And these are the direct casualties. No one can
know how many more deaths are advanced by
heat wave weather-how many diseased or aging
hearts surrender that under better conditions
would have continued functioning.
North American summers are hot; most summers
see heat waves in one section or another of the
United States. East of the Rockies, they tend to
combine both high temperature and high humidity
although some of the worst have been
catastrophically dry.
Gnaws National Weather Service
Heat Index Program
Considering this tragic death toll, the National
Weather Service (NEWS) has stepped up its efforts
to alert more effectively the general public and
appropriate authorities to the hazards of heat
waves-those prolonged excessive heat/humidity
episodes.
Based on the latest research findings, the NEWS
has devised the "Heat Index" (HI), (sometimes
referred to as the "apparent temperature"). The
HI, given in degrees F, is an accurate measure of
how hot it really feels when relative humidity (RH)
is added to the actual air temperature.
IMPORTANT: Since H values were devised for
shady, light wind conditions, EXPOSURE TO
FULL SUNSHINE CAN INCREASE HI VALUES BY UP TO 15 F. Also, STRONG
WINDS, PARTICULARLY WITH VERY HOT, DRY AIR, CAN BE EXTREMELY
HAZARDOUS.
The "Heat Index v. Heat Disorder" table that follows relates
ranges of HI with specific disorders, particularly for people in
higher risk groups.
HEAT INDEX/HEAT DISORDERS
Heat Possible heat disorders for people in higher
Index risk groups
130 or HEATSTROKE/SUNSTROKE HIGHLY
Higher LIKELY WITH CONTINUED EXPOSURE.
105-130 SUNSTROKE, HEAT CRAMPS OR
HEAT EXHAUSTION LIKELY AND
HEATSTROKE POSSIBLE WITH
PROLONGED EXPOSURE AND/OR
PHYSICAL ACTIVITY.
90-105 SUNSTROKE, HEAT CRAMPS AND
HEAT EXHAUSTION POSSIBLE WITH
PROLONGED EXPOSURE AND/OR
PHYSICAL ACTIVITY.
80-90 FATIGUE POSSIBLE WITH
PROLONGED EXPOSURE AND/OR
PHYSICAL ACTIVITY
Summary of News Alert Procedures
The NEWS will initiate alert procedures when the
HI is expected to exceed 105 F-110 F (depending on local climate)
for at least two consecutive days.
The procedures are:
* Include HI values in zone and city forecasts.
* Issue Special Weather Statements and/or Public
Information Statements presenting a detailed
discussion of (1) the extent of the hazard
Including HI values, (2) who is most at risk,
(3) safety rules for reducing the risk.
* Assist state/local health officials in preparing Civil
Emergency Messages in severe heat waves.
Meteorological information from Special Weather
Statements will be included as well as more
detailed medical information, advice, and names
and telephone numbers of health officials.
* Release to the media and over NOM's own
Weather Radio all of the above information.
How Heat Affects the Body
Human bodies dissipate heat by varying the
rate and depth of blood circulation, by losing
water through the skin and sweat glands, and-as
the last extremity is reached by panting, when
blood is heated above 98.6 degrees. The heart
begins to pump more blood, blood vessels dilate
to accommodate the increased flow, and the
bundles of tiny capillaries threading through the
upper layers of skin are put into operation. The
body's blood is circulated closer to the skin's
surface, and excess heat drains off into the cooler
atmosphere. At the same time, water diffuses
through the skin as perspiration. The skin
handles about 90 percent of the body's heat
dissipating function.
Sweating, by itself, does nothing to cool the
body, unless the water is removed by
evaporation-and high relative humidity retards
evaporation. The evaporation process itself works
this way: the heat energy required to evaporate
the sweat is extracted from the body, thereby
cooling it. Under conditions of high temperature
(above 90 degrees) and high relative humidity, the
body is doing everything it can to maintain 98.6
degrees inside. The heart is pumping a torrent of
blood through dilated circulatory vessels; the sweat
glands are pouring liquid-including essential
dissolved chemicals, like sodium and chloride-
onto the surface of the skin.
Too Much Heat
Heat disorders generally have to do with a
reduction or collapse of the body's ability to shed
heat by circulatory changes and sweating, or a
chemical (salt) imbalance caused by too much
sweating. When heat gain exceeds the level the
body can remove, or when the body cannot
compensate for fluids and salt lost through
perspiration, the temperature of the body's inner
core begins to rise and heat-related illness may
develop.
Ranging in severity, heat disorders share one
common feature: the individual has overexposed
or overexercised for his age and physical
condition in the existing thermal environment.
Sunburn, with its ultraviolet radiation burns, can
significantly retard the skin's ability to shed excess
heat.
Studies indicate that, other things being equal,
the severity of heat disorders tend to increase with
age-heat cramps in a 17-year-old may be heat
exhaustion in someone 40, and heat stroke in a
person over 60.
Acclimatization has to do with adjusting sweat-salt
concentrations, among other things. The idea is to
lose enough water to regulate body temperature,
with the least possible chemical disturbance.
Cities Pose Special Hazards
The stagnant atmospheric conditions of the heat
wave trap pollutants in urban areas and add the
stresses of severe pollution to the already dangerous
stresses of hot weather, creating a health problem
of undiscovered dimensions. A map of heat-related
deaths in St. Louis during 1966, for example,
shows a heavier concentration in the crowded
alleys and towers of the inner city, where air
quality would also be poor during a heat wave.
The high inner-city death rates also can be read
as poor access to air-conditioned rooms. While air-
conditioning may be a luxury in normal times, it
can be a lifesaver during heat wave conditions.
The cost of cool air moves steadily higher,
adding what appears to be a cruel economic side
to heat wave fatalities. Indications from the 1978
Texas heat wave suggest that some elderly people
on fixed incomes, many of them in buildings that
could not be ventilated without air conditioning,
found the cost too high, turned off their units, and
ultimately succumbed to the stresses of heat.
Preventing Heat-Related Illness
Elderly persons, small children, chronic invalids
those on certain medications or drugs (especially
tranquilizers and anticholinergics), and persons
with weight and alcohol problems are particularly
susceptible to heat reactions, especially during
heat waves in areas where a moderate climate
usually prevails.
Heat Wave Safety Tips
Slow down. Strenuous activities should be
reduced, eliminated, or rescheduled to the coolest
time of the day. Individuals at risk should stay in the
coolest available place, not necessarily indoors.
Dress for summer. Lightweight, light-colored
clothing reflects heat and sunlight, and helps
your body maintain normal temperatures.
Put less fuel on your inner fires. Foods
(like proteins) that increase metabolic heat
production also increase water loss.
Drink plenty of water or other non-alcohol
fluids. Your body needs water to keep cool.
Drink plenty of fluids even if you don't feel
thirsty. Persons who (1) have epilepsy or heart
kidney, or liver disease, (2) are on fluid
restrictive diets or (3) have a problem with fluid retention
should consult a physician before increasing their consumption of
fluids.
Do not drink alcoholic beverages.
Do not take salt tablets unless specified by a physician.
Persons on salt restrictive diets should consult a physician
before increasing their salt intake.
Spend more time in air-conditioned places. Air conditioning in
homes and other buildings markedly reduces danger from the heat.
If you cannot afford an air conditioner, spending some time each
day (during hot weather) in an air conditioned environment
affords some protection.
Don't get too much sun. Sunburn makes the job of heat
dissipation that much more difficult.
Know These Heat Disorder Symptoms
HEAT
DISORDER SYMPTOMS FIRST AID
SUNBURN Redness and pain. Ointments for mild cases
cases swelling of skin, if blisters appear
blisters, fever, headaches. and do not break. If
breaking occurs, apply dry
sterile dressing. Serious
extensive cases should be
seen by a physician.
HEAT Painful spasms usually in Firm pressure on cramping
CRAMPS muscles of legs and abdomen muscles, or gentle massage
possible. Heavy sweating. to relieve spasm. Give sips
of water. If nausea occurs,
discontinue use.
HEAT Heavy sweating, weakness, Get victim out of sun.Lay
EXHAUSTION skin cold, pale and clammy. down and loosen clothing
Pulse thready. Normal Apply cool,wet cloths.
temperature possible. Fan or move victim to air
Fainting and vomiting. conditioned room.Sips of
water. If nausea occurs
discontinue use. If
vomiting continues, seek
immediate medical atten
tion.
HEAT High body temperature(106F HEAT STROKE IS A SEVERE
STROKE or higher) Hot dry skin MEDICAL EMERGENCY. SUMMON
Rapid and strong pulse. EMERGENCY MEDICAL ASSIST-
Possible unconsciousness. ANCE OR GET THE VICTIM TO
A HOSPITAL IMMEDIATELY.
DELAY CAN BE FATAL.
Move the victim to a
cooler environment.
Reduce body tempera
ture with cold bath or
sponging. Use extreme
caution. Remove clothing,
use fans and air condi
tioners. If temperature
rises again, repeat
process. Do not give
fluids.
*For more information contact your local American
Red Cross Chapter. Ask to enroll in a first aid course.
Produced as a cooperative effort of NOAA's National
Weather Service, the Federal Emergency Management
Agency, and the American Red Cross.
American
Red Cross
*U.S. Government Printing Office 1992 322-758 NOAA/PA 85001
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