MONDAY, Feb. 23 (HealthDay News) -- Climate change will push summer temperatures higher and lead to more hospitalizations for respiratory problems, a European study finds.

The researchers analyzed a minimum of three years of hospital admission data in 12 European cities. They found that for every degree increase over 90 percent of a city's maximum apparent temperature (Tappmax), there was a 4 percent increase in respiratory-related hospitalizations. A rise in temperature was not linked to increases in admissions for cardiovascular or neurovascular-related conditions.

The Tappmax, which accounts for both air temperature and humidity, ranged from 14.7 degrees C (58 F) in Dublin, Ireland to 29.5 degrees C (85 F) in Valencia, Spain.

Respiratory-related hospital admissions increased among residents of all ages when temperatures moved above 90 percent of Tappmax, but people aged 75 and older were especially affected, the study found.

It's known that increased temperatures can boost cardiovascular emergencies, so the finding that cardiovascular-related hospitalizations did not increase with temperature came as a surprise. But the researchers suggested this may be because many patients who experience cardiovascular emergencies die before they can receive medical treatment.

The study appears in the first issue for March of the American Journal of Respiratory and Critical Care Medicine.

"These findings are important for public health because the prevalence of chronic diseases, such as [chronic obstructive pulmonary disease], is expected to increase in developed countries as a result of population aging," wrote Paola Michelozzi, head of environmental epidemiology in the epidemiology department at the Local Health Authority in Rome, Italy.

"Furthermore, under climate change scenarios, the increase in extreme weather events and certain air pollutants, especially ozone, are likely to further aggravate chronic respiratory diseases. Public health interventions should be directed at preventing this additional burden of disease during the summer season. The observed (differences) of the health effects indicates a need to tailor programs for individual cities," Michelozzi concluded.

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