New study shows exposure to plane noise at night causes vascular endothelial dysfunction, hence cardiovascular disease
A new study shows exposure to plane noise at night causes higher circulating levels of stress hormones eg. adrenaline, stiffened blood vessels, and these caused vascular endothelial dysfunction. These increase the chance of atherosclerosis leading to cardiovascular events. The scientists said: “In addition to being associated with an increased incidence of coronary heart disease, noise may serve as an acute trigger of cardiovascular problems. For example, a study published earlier this year established that for nighttime deaths, noise exposure levels two hours preceding death were significantly associated with heart-related mortality.” And “Importantly, comparing participants exposed to 30 versus 60 aircraft noise events per night revealed a dose-dependent worsening of endothelial function. Moreover, previous exposure to 30 aircraft noise events caused 60 events to have larger adverse effects on endothelial function. Thus, rather than any sort of habituation to the noise, there appeared to be a priming effect: prior exposure amplified the negative effect of noise on endothelial function.”
How Environmental Noise Harms the Cardiovascular System
Sound from cars, aircraft, trains, and other man-made machines is more than just annoying. It increases the risk of cardiovascular disease.
By Thomas Münzel and Omar Hahad (The Scientist)
Jun 1, 2021
Study shows exposure to plane noise at night higher circulating levels of stress hormones eg. adrenaline, stiffened blood vessels, and caused vascular endothelial dysfunction. These increase the chance of atherosclerosis leading to cardiovascular events
Some extracts from the article:
“The cardiovascular burden of traffic noise is particularly insidious, with annoyance reactions and sleep disturbances leading to an increased risk of heart disease. A 2015 report from the European Environment Agency linked exposure to car, truck, plane, and train sounds with nearly 1.7 million additional cases of hypertension, 80,000 additional hospital admissions, and 18,000 premature deaths due to coronary heart disease and stroke in Europe each year. A few years later, a metaanalysis conducted on behalf of the WHO supported these conclusions, with seven high-quality longitudinal studies collectively establishing that road traffic noise exposure was associated with an 8 percent increased risk of coronary heart disease.
Exposure to transportation-related noise is related to the annual loss of up to 1.6 million cumulative years of healthy life among people in Western Europe.—World Health Organization, data from 2011
In addition to being associated with an increased incidence of coronary heart disease, noise may serve as an acute trigger of cardiovascular problems. For example, a study published earlier this year established that for nighttime deaths, noise exposure levels two hours preceding death were significantly associated with heart-related mortality.
Translational aircraft studies in people
In 2013, to take a more controlled look at the effects of traffic noise, we and our colleagues conducted our first field study involving the exposure of healthy subjects to simulated aircraft noise overnight in their homes. On control nights, we simply had participants play a recording of normal background noise in their home on a standard portable audio system placed on their nightstands. On other nights, we had them play a looped recording of aircraft noise taken in the bedroom of a resident living in the vicinity of Düsseldorf airport in Germany with a window tilted open.
Using questionnaires, blood analyses, and physiological tests of endothelial function, we established that one night of simulated aircraft noise exposure reduced self-reported sleep quality, elevated circulating levels of stress hormones such as adrenaline, stiffened blood vessels, and caused vascular endothelial dysfunction, the latter two reflecting early subclinical signs of atherosclerosis and being independent predictors of future cardiovascular events and disorders. Importantly, comparing participants exposed to 30 versus 60 aircraft noise events per night revealed a dose-dependent worsening of endothelial function. Moreover, previous exposure to 30 aircraft noise events caused 60 events to have larger adverse effects on endothelial function. Thus, rather than any sort of habituation to the noise, there appeared to be a priming effect: prior exposure amplified the negative effect of noise on endothelial function.
More recently, we exposed healthy subjects to simulated nighttime train noise and similarly found that one night of exposure greatly impaired sleep quality and endothelial function. In addition, proteomic analysis of participant blood samples revealed substantial changes in circulating proteins that pointed to a higher susceptibility to inflammation and blood clotting.
Noise Damage Pathways
Epidemiological data have long linked exposure to noise such as aircraft, railway, or traffic sounds to increased risks of cardiovascular disease. And in recent years, experimental work has been revealing the biological mechanisms underlying that link. Specifically, researchers are finding that noise activates the brain’s limbic system, which plays a role in emotional regulation, the release of stress hormones into the blood, and controlling of the sympathetic nervous system. These stress responses can lead to cerebral and vascular inflammation, oxidative stress, and altered gene expression, sometimes culminating in endothelial dysfunction and cardiovascular disease.
Only a few other studies have provided mechanistic insight into the relationship between traffic noise exposure and cardiovascular disease. In 2017, Maria Foraster and her colleagues at the Swiss Tropical and Public Health Institute found, much as we did, that a decade of exposure to nighttime noise events, mainly related to road traffic noise, was associated with increased arterial stiffness in a cohort of 2,775 Swiss participants. That same year, a pooled analysis of more than 144,000 people in two large European cohorts from Norway and the Netherlands indicated that long-term exposure to road traffic noise was associated with higher levels of inflammation, blood lipids, and fasting glucose.
Molecular mechanisms of noise-induced harm
A surprising result to come out of our first field study was that the adverse effects of nighttime noise on endothelial function were ameliorated by the administration of vitamin C, which we gave to some participants after noise exposure. Vitamin C is an antioxidant, a scavenger of oxygen-derived free radicals. Thus, this finding hinted that increased oxidative stress within the vasculature may be responsible for noise-induced endothelial dysfunction.
To further elucidate the molecular mechanisms responsible for nonauditory noise-induced cardiovascular side effects, we established a novel mouse model and employed various noise pollution protocols. In the first study, we exposed mice to simulated aircraft noise around the clock for four days and observed increased blood pressure and elevated concentrations of stress hormones such as cortisol, noradrenaline, angiotensin II, and dopamine, along with raised blood pressure, suggesting the animals were stressed. This was accompanied by endothelial dysfunction and increased production of reactive oxygen species (ROS) within the vascular wall.
Blood vessels are lined with endothelial cells that produce powerful vasoconstricting and vasodilating substances such as the radical nitric oxide (NO.). But ROS—which are produced in cases of hypertension, high cholesterol, diabetes, chronic smoking, and other conditions that are risk factors for cardiovascular disease—attack and degrade NO., thus limiting its bioavailability. This leads to stiffer vessels, higher blood pressure, and the initiation of plaque buildup in arteries. It appeared that this might be the initial pathway by which noise causes cardiovascular damage.