Mid-Atlantic Weather Station (General List) -
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"System designed to let cities know when heat has become dangerous"
(Source: Scripps Howard, 6/9/99)
The weather has begun to broil much of the United States over the past
few
days. Yet not all heat is equal: It takes some pecial circumstances for
a
scorcher to become "killer" heat.
Rural and suburban areas with more green and less brick and concrete
tend
to fare better than major cities in a heat wave. But researchers have
only
recently learned how to predict when a spell of unusually hot
temperatures
is likely to turn deadly for some urban residents.
One system, pioneered in Philadelphia by University of Delaware
scientists in 1995, has been picked up in Washington, D.C., and Rome. It
may be duplicated in other cities, such as Shanghai, China, under
sponsorship of the United Nations Environment Program.
Although the combined numbers for temperature and humidity are
regularly used to calculate an estimate of human discomfort - the heat
index - the Delaware program takes several other factors into account
to give city health officials up to 60 hours warning of deadly
oppressive
heat. The actual warnings can only be issued in concert with the
National
Weather Service, however.
"Our system saves lives by identifying and then forecasting the
specific type of oppressive air mass known to kill large numbers of
people within a given city," said Delaware climatologist Laurence
Kalkstein.
"Health authorities can then reach out to children, senior citizens,
anyone in poor health and those in high-risk neighborhoods, where
heat-trapping homes make people more vulnerable to very hot weather
conditions," Kalkstein added.
Heat is thought to be the nation's deadliest weather most years, killing
an estimated 2,000 people annually. Researchers for the National Oceanic
and Atmospheric Administration reported in December that the frequency
of
extremely hot and humid days has been increasing across the United
States
by about two days per decade since 1949.
"We saw the largest and most statistically significant trends in some of
the most populated parts of the country, the eastern and western thirds
of
the continental U.S.," said NOAA research meteorologist Dian
Gaffen. "There has also been an accompanying increase in the frequency
of
multi-day heat waves, with increases of about 88 percent nationwide
during
the study period."
Most researchers believe that no matter how extensive or extreme
global warming turns out to be, the spread of development across more
square miles each year will exacerbate the lingering effects of urban
heat
islands, making for a widening public health problems. The Delaware
program analyzes National Weather Service forecasts in light of a city's
historic mortality rates, along with variables of
temperature, humidity and cloud conditions.
"A clear blue sky may be beautiful, but it can kill people if the
temperature rises high enough to cook residential buildings, which
stay shaded and cooler on cloudy days, even in heavy heat," said
Kalkstein.
The heat warning system also takes into account the type and severity
of a predicted hot air mass, the duration and timing of the heat wave
and the city's specific 'threshold" for temperatures that are known to
boost death rates.
The heat threshold varies widely among cities, Kalkstein said, because
people who live in warmer regions adapt to the environment, so that
southern and southwestern cities are built to accommodate warmer
weather.
Philadelphia and New York, for example, are less able to stand excess
heat
than Miami and Phoenix. Other cities that have high summer heat death
rates include Detroit, Chicago, Newark and St. Louis.
"Urban structures in these cities are often designed to trap heat, and
people aren't prepared for sudden or long-lasting heat waves,"
Kalkstein said.
If a warning is issued for Philadelphia, for instance, health officials
issue media alerts, activate phone hotlines, alert neighborhood
volunteers, open air-conditioned cooling centers and expand outreach to
the homeless to reach the most vulnerable residents.
"Putting into place an emergency response program involving a large
number of agencies and individuals requires a rapid shift of people
and resources," said Lawrence Robinson, a Philadelphia deputy health
commissioner who runs the city's emergency heat program.
The prediction system "allows us to launch these special services
exactly when they are needed to save lives," he said.
HOW HEAT CAN HURT YOU
Heat kills by pushing the body beyond its limits for naturally cooling
itself. Normally, evaporating perspiration is sufficient. But in extreme
heat - days of temperatures 10 degrees or more above the average high
for
an area, and high humidity - evaporation slows down.
Men tend to sweat more than women and are more susceptible to heat
illness
because they become dehydrated more quickly. Sunburn can also
significantly reduce the skin's ability to cool the body. If you feel
burned, try taking a shower to remove oils that may block pores and
prevent cooling.
Heat cramps are painful spasms that normally affect leg and abdominal
muscles, accompanied by heavy sweating. First aid calls for putting
pressure on the cramp, or a gentle massage, and sips of water.
Heat exhaustion is marked by heavy sweating, weakness, cool, pale
and clammy skin, a weak pulse and possibly fainting or vomiting. The
victim's temperature may still be normal. Treatment: Lie down in cool
place, loosen clothing. Apply cool wet cloths. Fan or move the patient
to a cool place. Give sips of water, but stop if nausea occurs. If
vomiting occurs, get medical help.
Heat stroke or sunstroke is marked by hot dry skin, very rapid pulse,
and a body temperature in excess of 106 degrees Fahrenheit and
possible loss of consciousness. The victim will probably not sweat.
This is a real medical emergency: Call 911 or get the victim to a
hospital. When waiting for ambulance, move to coolest place possible,
use a cool bath or sponges, fans, remove clothing. Do not give fluids.
Sources: Federal Emergency Management Agency, American Red Cross.
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