HEART ATTACK Study: Humidity heightens risk

Those over 70 had a higher risk of heart attack during periods of high humidity.
SCRIPPS HOWARD
It's not the heat, it's the humidity, people complain on sticky summer days. But a new study suggests that high humidity, even when it's chilly, boosts the risk for a heart attack among elderly people.
The study, published in the June issue of Heart, a specialty journal published by the British Medical Journal, looked at heart-attack deaths in Athens, Greece, for an entire year (2001) and compared rates against weather trends for temperature, atmospheric pressure and humidity levels recorded by the National Meteorological Society of Greece.
The number of heart attacks during the year was 3,126, 1,953 in men.
Overall, the proportion of deaths was a third higher in winter than in summer, with deaths among those aged 70 and older accounting almost entirely for the variation.
Among the elderly, death rates from heart attack were 3.5 times higher in June and seven times higher in December than rates for other age groups.
Yet the lowest recorded temperature for the coldest three days in December was 34 degrees Fahrenheit, with an average of 43 degrees for the month. The highest temperature, on two days in August, was 102 degrees, with an average high that month of 93 -- actually fairly temperate for the city, the researchers said.
Implications of study
Dr. Georios Giannopoulos, a professor of cardiology at the University of Athens and lead author of the study, said the higher death rate among the elderly in December shows that more effort needs to be made to educate seniors about the hazards of cold even in cities with climates as moderate as Athens'.
"It is apparent that more effort to protect the elderly during cold as well as hot weather is necessary, but that health-care and civil authorities also must consider the association of relative humidity with [heart-attack] mortality," Giannopoulos said.
The average daily temperature for the preceding week was the most significant factor influencing the daily heart-attack death rate in the elderly throughout the year. However, humidity was the biggest factor in the average monthly heart-attack death rate in the over-70 group.
In Athens, the most-humid month was December, with a relative humidity of about 73 percent. The least-humid month was August.
The researchers said it's not entirely clear how higher humidity levels could influence heart-attack mortality even when the weather's cool, but the fact that the relationship turned up only in monthly analysis suggests that the effect is felt over a longer range of time than are changes in temperature.
Many studies have noted a December peak in heart-attack deaths. Heart specialists often refer to the "Merry Christmas coronary" brought on by a combination of overindulgence in food and alcohol and the emotional stress of the holiday. But Giannopoulos noted that in Greece, Easter is celebrated much more intensely than Christmas, yet there is no equivalent peak in heart-attack deaths around that holiday in the spring.