Exposure to traffic noise increases the risk of suffering from a heart attack, researchers have found.
The noise from main roads and railway lines can lead to cardiovascular diseases such as myocardial infarction (MI), a German study shows.
Researchers examined information from state health insurers of over a million Germans over 40 living in Rhine-Main region of Germany.
Where they lived was matched to road, rail, and traffic noise exposure measurements for 2005.
When the analysis was restricted to patients who died of heart attack up to 2014/2015, a statistically significant association was found between noise exposure and the risk of heart disease.
Professor Dr Andreas Seidler of the Technical University Dresden said: "Traffic noise noise can trigger complex psychological and physiological stress reactions.
"In terms of the effects of traffic noise on the cardiovascular system, activation of the sympathetic nervous system is regarded as the chief mechanism, along with activation of the hypothalamus-pituitary-adrenal axis
"The World Health Organisation estimates that in the western part of Europe at least one million disability-adjusted life years (DALYs) are lost due to diseases induced by traffic noise."
The results show only an association between noise from road, rail and air traffic, and heart attack.
He added: "The comparably high estimated risks for all three modes of traffic noise in the subgroup of those who died-well above the respective estimated risks in the study population as a whole-suggest that traffic noise may affect not just the onset, but also the course of a MI.
"A large proportion of the population is exposed to levels of traffic noise that our case-control study indicates to be associated with increased-if only slightly increased-risks of MI.
"For this reason, effective control of traffic noise is a matter of great importance."
The study was published in journal Deutsches Arzteblatt International.