Last year, there were 580,000 homeless persons in the United States, with 28 percent living in California, where seven out of ten people live outside. This is roughly nine times the amount spent in any other state.

Heat Wave Grips New York
NEW YORK - AUGUST 02: A thermometer in the sun on the sidewalk indicates a temperature of 120 degrees Fahrenheit as people eat ice cream on the Upper West Side August 2, 2006 in New York City. Forecasters have called for high temperatures of 100 degrees in the city with the heat wave continuing through tomorrow. Photo by Chris Hondros/Getty Images

Heat Waves Endangering the Homeless

Heat Dome Over Northwest Brings Record Temperatures To Portland
PORTLAND, OR - JUNE 27: Austun Wilde rests with her two dogs, Bird Is The Wurd and Fenrir at a cooling center in the Oregon Convention Center on June 27, 2021 in Portland, Oregon. Record breaking temperatures lingered over the Northwest during a historic heatwave this weekend. Photo by Nathan Howard/Getty Images

Heat waves are only one of the many health risks homeless people face.

"The same weather that allows individuals in California to live without shelter also puts them at risk for a wide range of heat-related health issues that can lead to end-organ damage and even death," Tarik Benmarhnia said. He is a senior author of a recent study on homelessness and emergency department visits and an associate professor at the University of California, San Diego.

"People who are homeless are considered to be among the most vulnerable to extreme weather impacts, due to their exposure to the elements and high rates of preexisting health conditions like mental illness, as well as higher rates of smoking, drug, and alcohol use," Benmarhnia explained in a university news release.

San Diego's Homeless Population

His team studied emergency department data from two San Diego hospitals and temperature data for the city for the current study. San Diego has the nation's fifth-largest homeless population.

The data revealed that roughly 25,000 of the more than 242,000 emergency room visits between 2012 and 2019 were made by homeless persons.

The research focused on the summer months of May through September. During the most intense two-day heat waves observed, homeless persons attended ERs 1.29 times more during those months.

According to data published this month in the American Journal of Public Health, visits rose during lengthier heat waves with more intense temperatures.

Increased Mental Illness

According to the researchers, mental illness increases a homeless person's risk of heat-related disease, maybe because these people are less able to notice heat-related symptoms, seek a cool place, and rehydrate.

"Activating heat action plans to safeguard those suffering homelessness from heat waves is not only reasonable but is required," says research co-author Edward Castillo, a professor of emergency medicine at UCSD.

"Adapting therapies to specific populations might successfully reduce the impact of this increasingly widespread exposure on both patients and health care systems," Castillo noted.

Climate Change Involvement

A man drinking water due to extreme heat
Getty Images

The study's authors cautioned that climate change would raise the risk of heat disease among the homeless.

"As the threat of increasingly frequent and intense heat waves grows in the United States, particularly in California," study first author Lara Schwarz, a doctoral student in public health, said, "understanding and prioritizing the needs of this rapidly growing vulnerable population will be a critical action in developing and deploying effective adaptation strategies such as heat action plans to attenuate this burden."

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