Heat waves deadliest for blacks, diabetics

Heat waves, like the one that scorched the country in July, are more deadly for some people than for others.

Poor blacks and diabetics fare the worst. As you might guess, extreme heat is also hard on the elderly. But as you might not guess, extreme cold has a greater impact.

Also, the increase in risk on extremely hot days is smaller for deaths due to heart disease, such as heart attacks, than for other causes. Conversely, the increase in risk of dying from heart disease on extremely cold days is greater. Deaths from cardiac arrest show the largest increase at such times.

These revelations come from a study of almost 8 million deaths in 50 cities from 1989 to 2000, just completed by researchers at the Harvard School of Public Health (HSPH). Cities ranged from Minneapolis to Miami, from Boston to Honolulu.

Researchers counted the coldest and hottest 1 percent of days in each city as extreme temperature days.

"We aimed to identify specific causes of death that show the largest relative increases on extreme temperature days, an issue that has not been addressed by previous studies," says Mercedes Medina-Ramon, lead author of the study report. "Recognition of factors that convey susceptibility to die from a specific disease on extreme temperature days may provide relevant information to develop public health programs that will better target those most vulnerable."

Results of the statistical comparison of weather and deaths over 12 years show that blacks and those with a high school education or less are most likely to die on extremely hot days. That, the researchers conclude, could be related to poorer health, limited access to medical care, and lower quality housing.

In other words, heat waves of the kind that are becoming more common with global warming take their biggest toll on the socially disadvantaged.