Heat Wave: A Major Summer Killer

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Heat Wave: A Major Summer Killer 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.

 

NOAA’s National Weather Service Heat Index Program

Considering this tragic death toll, the National Weather Service (NWS) 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 NWS 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.

 

To find the HI, look at the Heat Index Chart. As an example, if the air

temperature is 95°F (found on the left side of the table) and the RH is 55%

(found at the top of the table), the HI-or how hot it really feels-is 110°F.

This is at the intersection of the 95° row and the 55% column.

 

IMPORTANT: Since HI 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.

 

Heat Index/Heat Disorders: Possible heat disorders for people in higher risk

groups.

Heat Index of 130° OR Higher: HEATSTROKE/SUNSTROKE HIGHLY HIGHER LIKELY WITH

CONTINUED EXPOSURE,

 

Heat Index of 105°- 130°: SUNSTROKE, HEAT CRAMPS OR HEAT EXHAUSTION LIKELY,

AND HEATSTROKE POSSIBLE WITH PROLONGED EXPOSURE AND/OR PHYSICAL ACTIVITY.

 

Heat Index of 90°- 105°: SUNSTROKE, HEAT CRAMPS AND HEAT EXHAUSTION POSSIBLE

WITH PROLONGED EXPOSURE AND/OR PHYSICAL ACTIVITY.

Heat Index of 80° - 90°: FATIGUE POSSIBLE WITH PROLONGED EXPOSURE AND/OR

PHYSICAL ACTIVITY

 

Note on the HI chart the shaded zone above 105°F. This corresponds to a level

of HI that may cause increasingly severe heat disorders with continued exposure

and/or physical activity.

 

The “Heat Index vs. Heat Disorder” table (next to the HI chart) relates ranges

of HI with specific disorders, particularly for people in higher risk groups.

 

Summary of NWS’s Alert Procedures

The NWS will initiate alert procedures when the HI is expected to exceed 105°-

1 10°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

Extent of the hazard including HI values

Who is most at risk

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 NOAA‘s own Weather Radio all of the above

information.

How Heat Affects the Body Human

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 over exercised 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.

 

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 SUNBURN: Redness and pain. In severe

cases swelling of skin, blisters, fever, headaches. First Aid: Ointments for

mild cases if blisters appear and do not break. If breaking occurs, apply dry

sterile dressing. Serious, extensive cases should be seen by physician.

 

HEAT CRAMPS: Painful spasms usually in muscles of legs and abdomen possible.

Heavy sweating. First Aid: Firm pressure on cramping muscles, or gentle massage

to relieve spasm. Give sips of water. If nausea occurs, discontinue use.

 

HEAT EXHAUSTION: Heavy sweating, weakness, skin cold, pale and clammy. Pulse

thready. Normal temperature possible. Fainting and vomiting. First Aid: Get

victim out of sun. Lay down and loosen clothing. Apply cool, wet cloths. Fan or

move victim to air conditioned room. Sips of water. If nausea occurs,

discontinue use. If vomiting continues, seek immediate medical attention.

 

HEAT STROKE (or sunstroke): High body temperature (106° F. or higher). Hot dry

skin. Rapid and strong pulse. Possible unconsciousness. First Aid: HEAT STROKE

IS A SEVERE MEDICAL EMERGENCY. SUMMON EMERGENCY MEDICAL ASSISTANCE OR GET THE

VICTIM TO A HOSPITAL IMMEDIATELY. DELAY CAN BE FATAL. Move the victim to a

cooler environment Reduce body temperature with cold bath or sponging. Use

extreme caution. Remove clothing, use fans and air conditioners. If temperature

rises again, repeat process. Do not give fluids. Persons on salt restrictive

diets should consult a physician before increasing their salt intake.

*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. NOAA/PA 85001

 

http://www.nws.noaa.gov/om/brochures/heat_wave.shtml

 

 

" The care of the Earth is our most ancient and most worthy, and after

all our most pleasing responsibility. To cherish what remains of it and to

foster its renewal is our only hope. " Wendell Berry

 

 

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