In a recent study published within the Canadian Journal of Cardiology, researchers assessed the association between heart problems and transportation noise.

Study: Too loud to handle?: transportation noise and heart problems. Image Credit: bibiphoto/Shutterstock

The variety of studies indicating adversarial health impacts because of this of traffic noise is on a gradual rise, with cardiovascular diseases (CVD) comparable to ischemic heart disease, arrhythmias, stroke, and heart failure being probably the most prevalent. Pathophysiological studies have revealed that nighttime noise may end up in sleep disturbances, comparable to too short sleeping periods and frequent interruptions of sleep, leading to an elevation in circulating stress hormone levels and, subsequently, a remarkable increase within the generation of reactive oxygen species (ROS) and inflammation throughout the vasculature in addition to the brain. Consequently, vascular dysfunction and arterial hypertension may raise the danger of heart problems.

The connection between noise and arterial hypertension

Several studies have assessed the impact of noise on blood pressure since noise results in mental stress reactions. Over 35 cross-sectional studies have found an elevated risk of 1.05 for hypertension as a consequence of road traffic noise. Subsequent studies yielded contradictory results, so the WHO panel considers the evidence supporting this link to be “very low.”

The connection between noise and hypertension found was higher with respect to nighttime noise than daytime noise. One other study found a correlation between aircraft noises and night and prevalent hypertension. However, no correlation was observed between daytime aircraft noise and blood pressure in patients with pre-existing coronary artery disease, which is consistent with nighttime noise events impacting endothelial function and arterial stiffness.

Noise and ischemic heart disease

Research has found a considerable correlation between road, aviation, and railway noise with ischemic heart disease. Yet, nearly all of experts have evaluated the standard of the evidence as low or extremely low. The strongest relationship was found between ischemic heart disease incidence and road traffic noise. Other noise studies have since established a link between aircraft noise and cardiovascular illness and even acute fatality.

Moreover, the best noise exposure group was substantially correlated with mortality for all CVD-related causes. Ischemic heart disease, heart failure, arrhythmia, and myocardial infarction displayed the strongest and most consistent relationships. Associations were stronger for females, individuals living in locations with low railway and road background noise, and people residing in pre-1970 buildings. Studies have also derived a population-attributable proportion of three% of the research population and concluded that nocturnal aircraft noise could cause acute cardiovascular mortality.

Noise and endothelial dysfunction

The endothelial function is a biomarker for subclinical atherosclerosis which is often noted in patients with cardiovascular risk variables like arterial hypertension, hypercholesterolemia, chronic smoking, oxidative stress, and diabetes. The elevated stress hormone levels by aspects like noise are typically accompanied by evidence of the increased generation of vascular ROS in addition to enhanced inflammation defined by elevated levels of infiltrating macrophages and cytokines like IL-6.

To find out whether transportation noise can affect endothelial function, the team examined the results of nocturnal airplane noise on flow-mediated dilation (FMD) in healthy participants. Healthy subjects exposed to overnight aircraft noise had poor sleep quality, higher stress hormone levels, endothelial dysfunction, and shortened pulse transit time. Effects of nighttime airplane noise on endothelial dysfunction in participants with preexisting coronary artery disease were even worsened. In response to nighttime railway noise, substantial endothelial dysfunction was observed as well. Endothelial dysfunction attributable to airplane and railroad noise responded favorably to the antioxidant vitamin C, indicating that oxidative stress is the underlying mechanism.

Noise and cardiovascular negative effects

On account of eNOS uncoupling, the noise boosts eNOS expression but decreases vascular nitric oxide (NO) levels. The noise increased the amounts of nitrotyrosine, interleukin (IL)-6, the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit (Nox2), nitrotyrosine-positive vascular proteins, and endothelin-1 within the bloodstream. Flow cytometry revealed a rise in natural killer cells and neutrophils infiltrating the vasculature.

Conclusion

The study findings showed that transportation noise could also be a major cardiovascular risk factor. Noise induces endothelial dysfunction, inflammation, oxidative stress, disruption of the vascular and cerebral circadian rhythm, and downregulation/decoupling of the neuronal NO synthase in humans. Future research will determine if conventional cardiovascular drugs, like angiotensin 1 receptor blockers (AT-II type 1) statins, angiotensin-converting enzyme inhibitors, antioxidant enzyme mimetics, or heart-healthy city design with the incorporation of more greenery, can effectively mitigate the adversarial health effects of noise.