May 24 (UPI) -- Socioeconomically disadvantaged areas are particularly vulnerable to the health effects of extreme heat and high ozone levels, a study published Monday by the Proceedings of the National Academy of Sciences found.
Over a 10-year period, neighborhoods with lower household incomes and higher levels of unemployment experienced increased hospitalizations due to respiratory problems caused by heat and air pollution, the data showed.
In addition, these neighborhoods also had higher populations of people who lacked health insurance and had slightly elevated levels of air pollution compared to wealthier areas, the researchers said.
"Exposure to ozone and extreme heat drive synergistic effects on respiratory hospitalizations in some areas of California," study co-author Lara Schwarz told UPI in an email.
"Neighborhoods with a lower median income and higher unemployment rates are particularly vulnerable to these effects," said Schwarz, a doctoral student in public health at University of California-San Diego with a master's degree in public health.
The findings suggest that public health officials "need to prioritize certain neighborhoods" in crafting approaches to minimize the health effects of extreme heat and air pollution, particularly "in the context of climate change," she said.
These include providing access to cooling centers and reaching out to at-risk populations during conditions of extreme heat and high ozone, Schwarz said.
Ozone, which often referred to as "smog," is a gas created from vehicle exhaust and industrial emissions. In high concentrations, it can damage the lungs and make breathing difficult, according to the American Lung Association.
Up to 40% of the population of the United States lives in cities with unhealthy air, recent research estimates.
For this study, Schwarz and her colleagues analyzed data on nearly 820,000 hospitalizations for respiratory problems in California from 2004 to 2013, based on the ZIP codes in which the patients lived.
ZIP codes that had more days with temperatures above 102 degrees Fahrenheit accounted for more of these hospitalizations than cooler regions, the data showed.
These ZIP codes also tended to have higher levels of unemployment, lower household incomes and higher uninsured populations.
In addition, ZIP codes with the highest rate of hospitalization also had ozone levels of more than 85 parts per billion, above the range recommended by the Environmental Protection Agency, they said.
"[Our] results can be used to inform early warning systems that consider both ozone and extreme heat," Schwarz said.
"Understanding what factors make a ZIP code vulnerable to these joint effects can be used to prioritize resources in particularly susceptible areas during an extreme heat event and ozone peak to maximize public health benefits and promote health equity," she said.