By 2050, the global population is expected to reach 10 billion people, most of whom live in urban areas that are full of harmful environmental influences.2 Two recent publications in the journal Circulation Research have dealt with the topic of traffic noise, which epidemiological studies have shown to be associated with an increased cardiovascular risk. The evidence is particularly strong for ischaemic heart disease, heart failure, and apoplexy.2,3 Studies in animals and humans describe disturbances in sleep, redox balance, and vascular function as well as disturbances in autonomic, epigenetic, and metabolic processes due to noise exposure.
Constant noise from road traffic, trains and aeroplanes leads to activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, which causes the release of stress hormones such as cortisol and catecholamines.2 This has two consequences: the stress hormones activate the renin-angiotensin-aldosterone system and, if chronically elevated, can promote cardiovascular risk factors such as hyperglycaemia, hypercholesterolaemia and high blood pressure. Elevated cortisol levels are also associated with truncal obesity and several studies have documented a link between traffic noise and obesity and obesity markers.2
Night-time traffic noise in particular leads to a fragmentation and shortening of sleep, an increase in stress hormone levels and increased oxidative stress in the blood vessels and brain. These factors can create a breeding ground for endothelial dysfunction, inflammation and arterial hypertension and thus increase cardiovascular risk.
"Exposure to noise not only exacerbates the negative health consequences of conventional cardiovascular risk factors, such as arterial hypertension and diabetes, but also accelerates atherosclerotic processes and increases the overall risk of cardiovascular disease," summarises the international group of noise experts.3