June 18 (UPI) -- Nearly 11,000 Americans died from natural heat exposure between 2004 and 2018, according to data released Thursday by the U.S. Centers for Disease Control and Prevention, which describes such deaths as a "continuing public health concern."
Ninety percent of the deaths from heat-related causes occurred during the summer, the agency found.
Three states -- Arizona, California and Texas -- accounted for the largest portion of these deaths, 37 percent, despite comprising just 23 percent of the nation's population, CDC researchers said.
Adults 45 years old and older, infants 1 year old and younger and men were up twice as likely to die from heat exposure, they said. In addition, black people were up to twice as likely to suffer a heat-related death than white people, according to the findings.
Most of the deaths were reported in urban centers and metropolitan areas, researchers said.
"Understanding patterns in heat-related mortality associated with comorbidity, age group, sex, race/ethnicity and urbanization levels could assist CDC and its public health partners in developing more effective ... intervention strategies," the agency researchers wrote.
Between 2004 and 2018, an average of 702 heat-related deaths were reported annually in the United States, with heat as the underlying cause in 415 cases and as a contributing factor in 287, the CDC report said.
Natural heat exposure was a contributing cause of death attributed to certain chronic medical conditions, alcohol poisoning and drug overdoses, the agency added.
When heat-related conditions were a contributing factor, major heart diseases were listed as the underlying cause of death in nearly half of all cases, making it the most common underlying cause of heat-related deaths, the CDC said.
Alcohol poisoning and drug overdoses were the underlying cause of 18 percent of all heat-related deaths, according to the agency.
A study published in the journal Environmental Research Letters in May estimated that the number of dangerously hot days in the United States would double by 2050 due to climate change.