Watch CBSN Live

Nature's Deadliest Killer

During a heat wave, deaths come miserably, one here, another there, with none of the drama of a hurricane or twister, flood or lightning. Yet an unyielding sun claims more lives than any of those events.

Year after year, only winter's cold kills more people than heat, according to the National Weather Service.

From 1979 through 1996, a yearly average of 381 people died of heat in the United States, the federal Centers for Disease Control and Prevention in Atlanta said. It calculated 6,864 heat deaths in that time span.

And the heat wave now baking much of the nation promises to add to the toll.

In the 40-year period from 1936 through 1975, almost 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, the agency said.

In 1906, an earthquake and fire in San Francisco claimed 452 lives, fewer than Los Angeles-area heat waves that caused 546 deaths in 1939; 946 in 1955, and 580 in 1963, a study in the journal Environmental Research found.

And many believe the tolls are understated, listing only those who succumb directly to temperature-related conditions such as heatstroke.

"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," the Weather Service reports.

Indirect casualties can be staggering, with the stress leading to a jump in deaths from heart attacks and other causes. During a 1966 heat wave, the mortality rate more than doubled in New York City and leaped fivefold in St. Louis.

The Centers for Disease Control noted that age is a major factor in succumbing to the heat, as half the victims are 65 or over.

Annual averages hide the huge tolls that can occur in severe years. For example, in 1980 an estimated 1,250 died and in 1995, a Chicago heat wave took 700 in that area.

Between 1936 and 1975, the Weather Service estimates, 20,000 Americans were killed by the heat.

Some deaths can be attributed to lack of air conditioning in a city home that is usually cooler. Others can be traced to power outages. Many occur simply because people don't consider the danger of heat.

Many who died in the 1995 Chicago heat wave were frail, frightened or alone. Some died behind boarded windows, their fear of intruders contributing to their demise. Others lost their lives when no one came to check on them.

The tragedy prompted Chicago to institute a heat emergency plan. When the heat index reaches 90 for three days, phone banks begin calling residents whose lives are most at risk and taking them, if necessary, to air-conditioned relief centers. Other cities have similar plans.

Cities are particularly dangerous in heat waves. Paving and buildings absorb heat and warm the temperature, and air movement is restricted by buildings.

The Weather Service uses a heat index, sometimes referrd to as the apparent temperature, to help gauge the danger. It is a measure of how hot it feels when relative humidity is added to the air temperature.

Written By Randolph E. Schmid

View CBS News In