Heat Waves

Leading Weather Fatality

These EHEs are the cause of the largest number of weather fatalities in the United States and, most likely, worldwide. In the United States, between 1998 and 2007, the 10-year average for heat fatalities was approximately 170 per year. Although international statistics are not available, the August 2003 heat wave in Europe was reported to cause over 15,000 deaths in France and an estimated 35,000 throughout all of Europe. In addition to heat-related fatalities, the incidence of medical conditions such as heat cramps, heat exhaustion, and heatstroke are also threats to human health. This type of weather also threatens the health of certain at-risk groups including the elderly, diabetics, those with heart disease, persons taking certain types of medications, social isolates, and other vulnerable groups. EHEs also may have unanticipated consequences on the health needs of others. For example, in 2008, Philadelphia area Red Cross blood donations were 1,000 units below the average of 1,200 per day because of donor cancellations due to a heat wave.

The incidence of EHE-related deaths is difficult to determine because of varying standards for determination of death across national and international jurisdictions. Typically, the cause of death is inferred from the circumstances of the death as well as the current weather. In addition, some deaths are accelerated due to the presence of high temperatures impacting individuals with various health-related vulnerabilities. Vulnerabilities are individual, such as advanced age and pre-existing conditions, but are also impacted by the physical and social environment of the individual.

EHEs are considered an increasing societal threat because of a number of factors. These include climate change; an increase in the size of the population, especially those of advanced age; and the increasing urbanization of contemporary societies. Urban environments enhance the effects of high temperatures by absorbing heat in highways and buildings. In addition, tall buildings, typical of metropolitan areas, also restrict airflow and trap heat from motor vehicles, air conditioners, and manufacturing activities. Urban areas also are less likely to have green spaces that can help to dissipate heat. The multiplier effect of urban areas on EHEs has led to the use of the term urban heat island (UHI) effect.

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