Lessons from a heat wave

As the death toll in Paris rises as a result of the summer heat wave, government officials are coming under heavy criticism that is sure to intensify in coming days. This script, familiar to us here in the Midwestern United States, played out in 1995 when over 700 Chicagoans died during a similar heat wave. The French are in the midst of learning a painful lesson—that urban heat waves are among the deadliest of all weather emergencies, especially when the government fails to prepare the public.

While hurricanes, tornadoes, floods, and lightning get most of the television time and newspaper headlines, heat waves are more deadly than any of those calamities. In the decade from 1992 through 2001 more persons in the United States died from excessive heat than from those other four causes combined. In contrast, with even a small number of deaths during a tornado or hurricane, any deaths due to the effects of heat are rarely reported until a prolonged heat wave affects a highly populated area.

This relative lack of notoriety feeds on itself. Even in urban areas, when people begin to succumb to excessive heat, public officials and epidemiologists are slow to take note. Many of the persons who die do not die directly from heat stroke; they are often victims of an increased incidence of cardiovascular disease as hot weather takes its toll on the heart. These deaths may not be considered heat related. Further, mortality tends to occur in groups in which death is not considered unusual—those at the extremes of age, the sick, and the grossly obese. Studies have shown that perhaps the greatest risk factor for death during hot weather is social isolation, such as the elderly shut-in or the mentally disturbed individual on psychiatric medication, victims unlikely to attract undue attention.

Because of these circumstances heat-related deaths in past decades were often underreported. This was the case in Chicago in 1995 when city officials consistently undercounted the number of persons who died when temperatures rose above 100°F. (The inner city hospital where I worked lacked central air conditioning, and at least two persons were found dead in their beds, victims of what was probably unrecognized and unreported heat stroke). Not until funeral homes and morgues started reporting tremendous increases in corpses was there a systematic approach to counting the number of individuals who were dying as a result of the heat.

To the credit of Mayor Richard Daley, he and his staff have learned their lessons well. The city works in concert with the National Weather Service, private meteorologists, and community organizations and if temperatures in Chicago are forecast to exceed 90°C, about 32°C, for any prolonged period, a graded series of warnings are issued on television, radio, and in the newspapers. Private and public resources are mobilized so that air conditioned cooling centers are made available to the public with transportation available to those unable to travel. The public (and the police) are encouraged to check on their neighbors, especially the elderly and infirm. Public health officials and hospitals are alerted to look for early patterns of emergency room admissions and deaths. Every summer Chicago has a "Heat Awareness Week" to prepare the population for hot weather emergencies. So far this approach seems to have had a measurable impact. While Chicago has had no prolonged heat waves comparable to that of 1995, in several smaller heat spells there has been little or no measurable increase in deaths.

Perhaps this is the beginning of a rapprochement. The less than cordial relations between France and America have only deteriorated during the current friction generated by international affairs. The recent hot-weather disaster demonstrates that we have much to share in terms of environmental emergencies. The French Government would do well to implement their own version of Chicagos's Heat Emergency Plan. In turn, they can share their experience so that the United States, with its more erratic climate and more frequent heat emergencies, can refine its urban heat plan. Once in a while, it takes heat to reduce friction.

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Correspondence to Cory M. Franklin.

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Franklin, C.M. Lessons from a heat wave. Intensive Care Med 30, 167 (2004). https://doi.org/10.1007/s00134-003-2024-4

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