Houston, Texas, USA : Exposure to environmental noise appears to increase the risk of heart attacks and strokes by fueling the activity of a brain region involved in stress response. This response in turn promotes blood vessel inflammation, according to preliminary research to be presented in Chicago at the American Heart Association’s Scientific Sessions.
The findings reveal that people with the highest levels of chronic noise exposure—such as highway and airport noise—had an increased risk of suffering cardiovascular events such as heart attacks and strokes, regardless of other risk factors known to increase cardiovascular risk.
The results of the study offer much-needed insight into the biological mechanisms of the well-known, but poorly understood, interplay between cardiovascular disease and chronic noise exposure, researchers said.
“A growing body of research reveals an association between ambient noise and cardiovascular disease, but the physiological mechanisms behind it have remained unclear,” said study author Azar Radfar, M.D., Ph.D., a research fellow at the Massachusetts General Hospital in Boston. “We believe our findings offer an important insight into the biology behind this phenomenon.”
Researchers analyzed the association between noise exposure and major cardiovascular events, such as heart attacks and strokes, among 499 people (average age 56 years), who had simultaneous PET and CT scan imaging of their brains and blood vessels. Diagnostic validation was done in a subset of 281 subjects.
All participants were free of cardiovascular illness and cancer at baseline. Using those images, the scientists assessed the activity of the amygdala—an area of the brain involved in stress regulation and emotional responses, among other functions. To capture cardiovascular risk, the researchers examined the participants’ medical records following the initial imaging studies. Of the 499 participants, 40 experienced a cardiovascular event (e.g., heart attack or stroke) in the five years following the initial testing.
To gauge noise exposure, the researchers used participants’ home addresses and derived noise level estimates from the Department of Transportation’s Aviation and Highway Noise Map.
People with the highest levels of noise exposure had higher levels of amygdalar activity and more inflammation in their arteries. Notably, these people also had a greater than three-fold risk of suffering a heart attack or a stroke and other major cardiovascular events, compared with people who had lower levels of noise exposure. That risk remained elevated even after the researchers accounted for other cardiovascular and environmental risk factors, including air pollution, high cholesterol, smoking and diabetes.
Additional analysis revealed that high levels of amygdalar activity appears to unleash a pathway that fuels cardiac risk by driving blood vessel inflammation, a well-known risk factor for cardiovascular disease.
The researchers caution that more research is needed to determine whether reduction in noise exposure could meaningfully lower cardiovascular risk and reduce the number of cardiovascular events on a population-wide scale.
In the meantime, however, the new study findings should propel clinicians to consider chronic exposure to high levels of ambient noise as an independent risk factor for cardiovascular disease.
“Patients and their physicians should consider chronic noise exposure when assessing cardiovascular risk and may wish to take steps to minimize or mitigate such chronic exposure,” Radfar said.
A separate study found that air pollution and noise increases risk for heart attacks.
Air pollution and noise increase risk for heart attacks
Where air pollution is high, the level of transportation noise is usually also elevated. But car, train and aircraft noise also increase the risk for cardiovascular diseases and diabetes, as previous research has demonstrated. Studies investigating the effect of air pollution without sufficiently taking into account the impact of noise on health might overestimate the effect of air pollution. These are the results of a comprehensive study conducted by the Swiss Tropical and Public Health Institute (Swiss TPH), which was published today in the peer-reviewed European Heart Journal.
The study looked at the combined effects of air pollution and transportation noise for heart attack mortality by considering all deaths that occurred in Switzerland between 2000 and 2008. Analyses that only included fine particulates (PM2.5) suggest that the risk for a heart attack rises by 5.2 percent per 10 μg/m3 increase in the long-term concentration at home. Studies that also account for road, railway and aircraft noise reveal that the risk for a heart attack attributable to fine particulates increases considerably less; 1.9 percent per 10 μg/m3 increase. These findings indicate that the negative effects of air pollution may have been overestimated in studies that fail to concurrently consider noise exposure.
“Our study showed that transportation noise increases the risk for a heart attack by 2.0 to 3.4 percent per 10 decibels increase in the average sound pressure level at home,” said Martin Röösli, head of the Environmental Exposures and Health Unit at Swiss TPH, and lead author of the published research. “Strikingly, the effects of noise were independent from air pollution exposure.”
Effect of noise and air pollution are additive
The study also found that people exposed to both air pollution and noise are at highest risk of heart attack. Hence, the effects of air pollution and noise are additive. “Public discussions often focus on the negative health effects of either air pollution or noise, but do not consider the combined impact,” said Röösli. “Our research suggests that both exposures must be considered at the same time.”
This has implications for both policy as well as future research. Hence, Röösli and co-researchers recommend including transportation noise exposure in any further research related to air pollution and health to avoid overestimating the negative effects of air pollution on the cardiovascular system.
Data from across Switzerland
The study included all deaths (19,261) reported across Switzerland from the period 2000 to 2008. The air pollution (PM2.5) was modeled using satellite and geographic data, calibrated with air pollution measurements from 99 measurement sites throughout Switzerland. Nitrogen dioxides (NO2) were also modeled using 9,469 biweekly passive sampling measurements collected between 2000 and 2008 at 1,834 locations in Switzerland. Transportation noise was modeled by well-established noise propagation models (sonRoad, sonRAIL and FLULA 2) by Empa and n-sphere. The air pollution and the transportation noise models were applied for each address of the 4.4 million Swiss adult citizen (aged 30 years and above).
Citation for second study: Harris Héritier et al. A systematic analysis of mutual effects of transportation noise and air pollution exposure on myocardial infarction mortality: a nationwide cohort study in Switzerland, European Heart Journal DOI: 10.1093/eurheartj/ehy650
A third study found that transportation noise increases risk for cardiovascular diseases and diabetes.
Transportation noise increases risk for cardiovascular diseases and diabetes
Transportation noise increases risk for cardiovascular diseases and diabetes. This is shown by the first results of the SiRENE study under the lead of Swiss TPH, which was presented in the framework of the ICBEN Congress (International Commission on Biological Effects of Noise) in Zurich.
How transportation noise affects the health of people remains in many aspects unexplained. Since 2014, an interdisciplinary Swiss consortium has been studying the short- and long-term effects of transportation noise for the population in Switzerland in the frame of the SiRENE study of the Swiss National Science Foundation (SNSF).
Increased risk for developing cardiovascular diseases
The results published so far show that aircraft, rail and road traffic noise in Switzerland leads to adverse health effects. For cardiovascular disease mortality, the most distinct association was found for road noise. The risk of dying of a myocardial infarction increases by 4 per cent per 10 decibel increase in road noise at home. Also the risk of hypertension and heart failure increases with transportation noise. “Particularly critical are most likely noise events at night regularly disturbing sleep,” says Martin Röösli, principal investigator of SiRENE and professor of environmental epidemiology at Swiss TPH and the University of Basel. “The threshold for negative health impact is lower than previously suspected.”
Noise also favours Diabetes
In addition to cardiovascular diseases, transportation noise also increases the risk of developing diabetes. This is shown by an examination of 2,631 people exposed to different degrees of noise pollution. “Two mechanisms play a role,” explains Nicole Probst-Hensch, Head of the Department of Epidemiology and Public Health at Swiss TPH. “On the one hand, the chronic release of stress hormones influences insulin metabolism. On the other hand, sleep problems are known to negatively affect metabolism in the long term.”
More effective noise protection
The results that were published in the frame of the SiRENE study will provide important information for the Swiss authorities with regard to improving noise protection and to potentially adjusting the noise limits in the Noise Abatement Ordinance (NAO). The health impact of transportation noise is substantial when considering the entire population in Switzerland, causing external costs of an estimated CHF 1.8 billion each year. For the health of individuals, however, factors such as exercise and smoking are much more important according to Röösli.
The study results were presented at the ICBEN (International Commission on Biological Effects of Noise) meeting on 20 June 2017 in Zurich. ICBEN is the world’s largest congress on the health effects of noise and takes place every three years.
A fourth study found that long term exposure to aircraft noise is linked to high blood pressure
Long term exposure to aircraft noise linked to high blood pressure
Long term exposure to aircraft noise, particularly during the night, is linked to an increased risk of developing high blood pressure and possibly heart flutter and stroke as well, suggests research published online in Occupational & Environmental Medicine.
The research team drew on data from 420 people living near Athens International Airport in Greece, where up to 600 planes take off and land every day.
They formed one of six groups of people living near six large European airports who had taken part in the HYENA study, which assessed the potential health impacts of aircraft noise in 2004-6.
The aircraft and road traffic noise exposure levels estimated for their postcodes at that time—less than 50 decibels to more than 60 dB—were used for the current study.
Daytime aircraft noise was defined as that occurring between 0700 and 2300 hours, and that occurring between 2300 and 0700 hours was defined as night-time aircraft noise.
Around half of the participants (just under 49%) were exposed to more than 55 dB of daytime aircraft noise, while around one in four (just over 27%) were exposed to more than 45 dB of night-time aircraft noise. Only around one in 10 (11%) were exposed to significant road traffic noise of more than 55 dB.
Over a nine year period, 71 people were newly diagnosed with high blood pressure and 44 were diagnosed with heart flutter (cardiac arrhythmia). A further 18 had a heart attack.
Exposure to aircraft noise, particularly at night, was associated with all cases of high blood pressure, and with new cases.
When all cases of high blood pressure were included, every additional 10 dB of night-time aircraft noise was associated with a 69% heightened risk of the condition. When only new cases were included, every additional 10 dB was associated with a more than doubling in risk.
Exposure to night-time aircraft noise was also associated with a doubling in risk of heart flutter diagnosed by a doctor, but this only reached statistical significance when all cases, not just new ones, were included in the calculations.
A heightened risk of stroke was similarly linked to increasing aircraft noise exposure, but this was not statistically significant, possibly because of the small number of cases involved, suggest the researchers.
The associations between road traffic noise and ill health were much weaker and less consistent, the findings showed.
This is one of the first long term follow-up studies of aircraft noise so it’s not possible to draw conclusions about cause and effect at this stage until more evidence/studies become available, say the researchers.
They point out that they were unable to look at specific causes of death among the 78 people who died between 2004-6 and 2013. The numbers studied were also relatively small, and it wasn’t possible to account for the potential effects of air pollution.
Nevertheless, a growing body of evidence links noise exposure to ill health, they emphasize.