As extreme summer temperatures contribute to the uptick in blackouts across the country, a new study shows that when the two events coincide the public health risks can be profound, especially in the Southwest.
The study, published last week in the journal Environmental Science & Technology, found that if a multi-day blackout occurs in Phoenix, Arizona, during a heat wave, more than half of the city's population would require emergency medical care to treat heat-related illnesses, and up to 1% of the population – about 13,000 people – would die.
“A blackout and a heat wave at the same time is probably the greatest health risk for the United States,” said Brian Stone, the study's lead author and a professor of environmental planning at Georgia Institute of Technology. “That has only become all the more probable and frequent since we started this study [six years ago].”
Stone and his team modeled how many deaths and hospitalizations would occur if a heat wave happened during a five-day blackout. They ran simulations based on historical data from three climate-representative cities – Atlanta, Georgia; Detroit, Michigan; and Phoenix – and factored in a number of variables, like the temperature outside versus inside a home, different types of buildings and how power is restored in different sectors of the city over time.
Stone said the study's alarming numbers partly come down to human biology.
“We really do have a very well-defined physiologic threshold for heat risk, and that's our core body temperature – 98.6 degrees,” he said. “If we can't sustain that core body temperature in the range of that critical threshold, we can get sick and succumb to heat illness very quickly. It doesn't take very long. And so as environmental temperatures approach that core body temperature, we're getting closer and closer to seeing more and more people at risk.”
The scenarios in the study also showed that Atlanta and Phoenix wouldn't have enough beds to accommodate those needing to be hospitalized.
Stone said the study's findings are also applicable to other parts of the Mountain West.
“I would not expect the numbers to be so dramatically different from Phoenix,” he said. “The fraction of the population getting ill would be within an order of magnitude. I mean, we're going to see heat waves that can be quite extreme in dry regions of the country, even at higher elevations."
The Environmental Protection Agency reports that the average heat wave in major U.S. urban areas has been about four days long — an entire day longer than in the 1960s. Stone said cities are not prepared for these changes once blackouts are added to the equation.
“We would expect to see a large number of people getting sick, potentially a large number of people dying," Stone said. "An emergency response system and health care system that could not handle that could be overwhelmed by that demand and risk.”
Along with ensuring sufficient emergency response, Stone said cities should invest in large cooling centers with backup power generation to dramatically reduce the urban heat island effect. More shade structures and cool roofs would also help and would not require electricity.
“In Phoenix, if every house and every building had a cool roof, you would reduce the number of people who would potentially die or go to the hospital by about two-thirds,” Stone said.
As temperatures start to hit record highs before the summer months really begin, Stone emphasized that the prospect of such scenarios is “quite real.”
“We should all be taking this quite seriously now, and not in ten years — right now,” he said. “This could happen in the summer.”
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
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