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 airconditioning 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

Know These Heat Disorder Symptoms

HEAT

DISORDER SYMPTOMS FIRST AID*

SUNBURN Redness and pain. In severe

cases swelling of skin,

blisters, fever, headaches.

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.

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.

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.

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.

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.

*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.

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

NOAA/PA 85001
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 authorites 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 Chat-t. 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 95O row and the 55% column.

IMPORTANT: Since HI values were devised for

shady, light wind conditions, EXPOSURE TO

Heat Index/Heat Disorders

Heat Possible heat disorders for

Index people in higher 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

FULL SUNSHINE CAN INCREASE HI VALUES

BY UP TO 15°F. Also, STRONG WINDS,

PARTICULARLY WITH VERY HOT, DRY AIR,

CAN BE EXTREMELY HAZARDOUS.

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°- 110°F (depending

on local climate) for at least two consecutive days.

The procedures are:

l Include HI values in zone and city forecasts.

l 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.

l 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.

Heat Index

Chart

Air Temperature

and Relative

Humidity versus

Apparent

Temperature

RELATIVE HUMIDITY (%)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

140

135 Heat lndex

l Release to the media and over NOAA‘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 chlorideonto 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.