If the temperature is extremely high or low, the number of deaths caused by heart failure or stroke increases significantly, a study showed on Monday.

The study published in the trade journal "Heart" was carried out by the Helmholtz Zentrum Munich and the German Research Center for Environment and Health.

According to the Helmholtz Zentrum Munich, statistics continued to suggest that the number of deaths rises in the extrem hot weather, as the heat in the summer of 2003 in Western Europe claimed around 22,000 lives.

A team of researchers, after examining in three Bavarian towns the impact of extreme temperatures on the number of deaths caused by cardiovascular diseases, also found the low temperature was also a cause of deaths.

As the results showed, if the temperature increases from 20 celsius to 25 celsius, or drops from 1 celsius to celsius, the number of deaths increase significantly by 9.5 percent and 7.9 percent respectively, due to the cardiovascular diseases.

Meanwhile, the study also pointed out that mainly elderly people are affected by the hot or cold weather.

"Our findings confirm results from our previous studies that already gave evidence that older people and people with underlying medical conditions are particularly sensitive to heat and cold," says Alexandra Schneider from the Institute of Epidemiology II at Helmholtz Zentrum Munich.

"If we're aware of the health effects resulting form the air temperature, we can identify the most vulnerable groups and take preventive measures," said Schneider.