Health Problems Mount After Day Three of a Heat Wave

PADOVA, Italy, Aug. 10 -- It the number of back-to-back hot days, not record setting temperatures, that transforms "dog days" from public discomfort to public health concern, reported researchers here.

At least four consecutive, hot, humid days were needed to observe a major increase in heat-related hospitalizations for people ages 75 or older, Giuseppe Mastrangelo, M.D., of the University of Padova, and colleagues, reported in the August issue of BMC Public Health.

After four days, hospitalizations for heat-related conditions increased more than twofold (P

Hospitalizations for fracture of the femur or for circulatory disease did not "show any increase with duration or intensity" of the heat wave, they wrote.

One explanation for the lack of increase in hospitalizations for cardiovascular disease may be that "deaths from circulatory diseases occur rapidly in isolated people before they reach a hospital" or the finding could just be a matter of chance, the investigators wrote.

Finally, they concluded, their findings support the current public health approach to heat waves in which alerts are usually issued after three consecutive days.