Cardiovascular Health And Noise Pollution

Noise pollution is a term used to describe the human-created noise that may damage the human, animal and environmental welfare. Excessive noise represents not only an auditory disturbance in itself, but it also causes non-auditory adverse effects. It impacts normal sleep patterns, concentration, relaxation and communication.

In recent years, the noise pollution became a hot topic in popular media. The noise is also emerging as one of the main public health concerns. Since the sound information captured by the auditory system is later received and processed by different parts of the brain, it is thought that noise pollution can be an underlying stimulator for the development of a number of problems, including cognitive development of children, endocrine imbalance and cardiovascular disorders.

High level of noise does influence physiological parameters of human body

On his “Cardiovascular Effects of Noise” for the Encyclopedia of Environmental Health, Wolfgang Babisch explained that noise has a stress-inducing nature which causes it to deeply influence the functioning of the endocrine and the autonomic nervous systems. According to studies carried out by the World Health Organization, when people are exposed to high levels of noise for a short period of time, their blood pressure, heart rate, cardiac output and blood vessel constriction rates are altered. These are parameters naturally controlled by the autonomic nervous system.

Our body is designed to respond to stress and it can do so when faced with a variety of averse stimuli, noise included. The problems seem to arise in the long-term. Physiological setpoints (i.e. the values and conditions the body deems as “normal”) deregulate, and functional changes in the physiological stress mechanisms set in. This exerts an adverse effect on the vital body functions, inducing alterations in blood pressure, cardiac function, blood lipids, blood clotting factors and blood sugar levels. As a consequence, individuals will possess an increased risk of suffering from hypertension, ischemic heart disease and atherosclerosis (i.e. accumulation of fat deposits that clog the major arteries) in the future. And one of the most important things to note is that this not only affects adults, but also children.

Read More: Tea Drinking Improves Cardiovascular Health

Significant effect of noise on children is well documented

One of the first studies conducted in children, in 1968, consisted of exposing different groups to different levels of road traffic noise. Astoundingly, it was found that the school children in the group exposed to the highest level of noise had blood pressure readings that were 10 mmHg higher than usual immediately after exposure. In 1995, in Bratislava, a similar study of the effect of varying degrees of noise in school children found even more significant differences between the kids who had been exposed to low levels and those who had been exposed to high levels of noise. This confirmed the existence of a dose-response relationship. Many other studies have observed similar differences and it is known, to some extent, that blood pressure levels in infancy and adolescence can influence the blood pressure levels in adulthood. However, studies over the full age range are missing, making it difficult to predict any future health problems that children who are exposed to intense noise pollution will suffer from.

Noise Pollution Does Affect Cardiovascular Health, But The Extent Of Problem Needs To Be Further Investigated

When it comes to adults, a number of studies also suggest the existence of a relationship between the blood pressure levels and the high levels of traffic or aircraft noise. Interestingly enough, other studies (conducted in Germany, Austria and the Netherlands) found an inverse relationship, with the subjects in the highest noise category showing lower blood pressure readings. Therefore, there doesn’t seem to be enough evidence that exposure to noise increases mean blood pressure. And if we’re talking about hypertension per se, the pattern is also inconsistent. For example, when the association between noise from road traffic and railway traffic and the prevalence of hypertension was studied in the Swedish town of Sollentuna in 1998, researchers found a significant relative risk in the road traffic exposed group. However, similar studies conducted in Amsterdam didn’t reveal any increase in the risk of hypertension in subjects that were more disturbed by noise in comparison to those who were less disturbed by noise. 

A meta-analysis published in the Environmental Health Perspectives journal which analyzed over 40 occupational and community centered studies contains several interesting findings. Occupational noise studies, i.e. the studies of people who are exposed to high levels of noise in their workplace, are as contradictory as the findings mentioned above regarding the blood pressure. However, when it comes to the risk of hypertension, there seems to be indeed a relationship with occupational noise, but not with road traffic noise, confirming the conclusions of previous researchers.

High level of aircraft noise can be a serious concern

More recently, a group of investigators decided to evaluate the existence of a relationship between aircraft noise and the risk of stroke, coronary heart disease and cardiovascular disease in general. The study, published this year in the British Medical Journal, involved the assessment of several residents living in a number of neighborhoods surrounding Heathrow Airport in London. It was found that for all of the above-mentioned ailments (stroke, coronary heart disease and cardiovascular disease) the risk of hospital admission was related to increased aircraft noise areas. When it came to mortality, the same relationship was found, although the number of events registered was much smaller than the number of hospital admissions. The data were particularly convincing of the existence of a relationship between the daytime noise and the coronary heart disease-related mortality.

Here are some of the biggest noise pollutants linked to cardiovascular concerns:

1. Road Traffic Noise: This is one of the most studied and prevalent sources of noise pollution in urban settings. Chronic exposure to road traffic noise has been linked to an increased risk of hypertension, ischemic heart diseases, and other cardiovascular disorders.

2. Railway Noise: Those living close to railways, especially busy transit lines, can experience increased cardiovascular risks due to the chronic noise exposure.

3. Industrial Noise: Industries, factories, and construction sites often produce significant levels of noise. Workers and nearby residents exposed to these noise levels can face increased cardiovascular risks.

4. Recreational Noise: Loud music events, festivals, or venues can expose attendees to high noise levels for prolonged periods. While these are often short-term exposures compared to the continuous noise from traffic or industry, they can still pose risks if exposure is frequent.

5. Wind Turbine Noise: Some studies have suggested that the infrasound and low-frequency noise produced by wind turbines might have health impacts, including cardiovascular effects, but the evidence is not as robust as that for road traffic or aircraft noise.

Read More: Signs and Symptoms of High Blood Pressure

Although the biologic mechanism underlying the assumption that cardiovascular problems must be seen as a consequence of noise-induced stress is plausible and supported by several studies, this connection involves a very complex mechanism. Many variables come into play and some populations might be more sensitive to the effects of noise pollution. To this day, the scientific validity of this theory hasn’t been fully validated. However, the absence of scientific evidence does not necessarily mean the absence of a relationship between the noise pollution and cardiovascular diseases.