Continued exposure to noise boosted the risk of a heart attack 140 percent, while air pollution led to more hospitalizations for people who had previously had heart attacks, according to two separate studies presented at a congress by the European Society of Cardiology in the southern city of Munich.

"There was a direct relationship between the degree of air pollution and the frequency of illnesses," said Stephanie von Klot of the GFS environment and health research center in the southern German town of Neuherberg.

"You see the increased risk (of heart attacks) even below the current legal limits (for air pollution)," added the GSF project director Annette Peters.

A slight rise in diesel exhaust in the air led to a 2.5 percent increase in hospitalizations.

The findings were based on a EU-backed study of 22,000 heart patients in the European cities of Augsburg, Barcelona, Helsinki, Rome and Stockholm.

Noise pollution, meanwhile, was found to send stress hormone levels soaring, affecting blood pressure and blood lipid concentration, according to a study by the Charite University Clinic in Berlin.

The researchers examined 4,115 heart patients' exposure to excessive noise levels.

Women who faced a constant level of noise at home had a significantly higher risk of heart attacks. Although the study found no increased likelihood of attacks among men under similar conditions, a similarly elevated risk was observed among men in a noisy workplaces.

The experts put the difference down to varying psychological reactions to noise based on the priorities of the patient.

"The risk for men can be realistically decreased with appropriate noise protection measures at the workplace. But advising women to seek out a quieter environment is not as easy to implement," said Professor Stefan Willich of Charite.