February 20, 2020
Dr. Ma. Haidee Ibanez, M.D.
Sound is a valuable part of our everyday life because it allows us to communicate. Distinguishing sound from noise is important because noise can have negative effects in both our physical and mental health. Noise is one of the underestimated threats that can cause numerous short and long-term health problems.
Prolonged or excessive exposure to noise has been associated with a number of health effects both in psychosocial and physiological health responses. Psychological problems such as sleep disturbance, stress, poor work and school performance could occur. Recent studies have proved that noise exposure could not only cause auditory effects but it could result to cardiovascular problems ranging from hypertension and ischemic heart disease.
A recent study done in Taiwan showed that various types of noise exposure was associated with small but significant increase in both systolic blood pressure (SBP) and diastolic blood pressure (DBP). The researchers found that the general effect of noise on cardiovascular parameters seemed to be slightly greater in men than women. The result of the study suggests that exposure to noise, particularly high frequency noise, negatively impacts blood pressure. Tonality and fluctuation strength of noise impacts systolic blood pressure.
What is Noise?
Noise is defined by the American National Standard Acoustical Terminology as any unwarranted disturbance within a useful frequency band, such as undesired effects of electric waves in a transmission channel or device. To define it simply, noise is an unwanted or disturbing sound which can interfere with normal activities such as sleeping, conversation, reproduction, and communication and it can disrupt or diminish one’s quality of life.
The human ear is extremely sensitive and it does not cease to function even though a person is asleep. During sleep, the ears still pick up and transmit the sounds to the nerves and the brain still processes sounds or noise, causing the body to react in different ways. Noise heard during sleep could set off the acute response of the body which could cause a rise in the blood pressure and heart rate thus potentially activating a state of hyperarousal. This response can lead to cardiovascular disease and other health problems.
The intensity of sound or noise is measured in decibels or dB. The intensity of sounds could range from 10-100 dB. Sounds more intense than 30 dB are called noise. Scientist has set the maximum sound limit to 75- 85 dB, after which hearing can be damaged. The WHO considers the sound of 45 dB as ideal for cities but most big cities have a measurement that exceeds 90 dB.
Where Does Noise Come From?
Sources of noise pollution could be divided into two categories namely: environmental and human sources. The environment produces various sounds coming from lightning, thunderstorms, earthquake, landslides, volcanic eruptions and etc.
Human sources of noise pollution could be a result of rapid industrialization and urbanization in order to meet the demands of the increasing population.
Noise pollution is an integral part of the industry. Factories and commercial establishments have machines that create a variety of sounds that could be enough to damage hearing and concentration. Residential areas in cities are adjacent to each other, hence the noise of radios, television, and various types of sounds are evident. An increase in the population could mean an increase in domestic noise.
In constructing establishments, buildings, and even houses, heavy equipment’s and machines are needed. Even the use of a simple hammer could create noise that could already disturb a person. Uncontrolled fireworks could cause noise pollution especially during festivals and fairs. Political activities which include demonstrations and rallies could also be sources of noise.
Effects of Noise Pollution and Diseases Caused by Noise Pollution
Noise exposure has been associated with a number of health effects both in psychosocial and physiological health responses. Psychosocial effects caused by noise could range from annoyance, disturbance of daily activities, reduction in sleep and, poor job performance. The most common physiological effect of noise exposure is mostly auditory. There is less agreement in studies to the non-auditory physiological effects of noise exposure.
Cardiovascular effects of Noise Pollution
Cardiovascular diseases are the leading cause of mortality in most developed countries. Recent research has indicated that chronic exposure to noise is associated with increased risk of cardiovascular diseases such as coronary heart disease and hypertension.
A study done by Shih Yi Lu and company last 2017 showed that acute exposure of noise between male and female young adults had a significant difference in the mean values for SBP, DBP, and heart rate. The study estimated a blood pressure increase of 0.85 mmHg/10 dB and 0.71 mmHg/10dB in SBP and DBP, respectively. Men are generally at greater risk for cardiovascular and renal disease than age-matched, premenopausal women. Blood pressure was higher in males than in females at similar ages, while heart rate was statistically and significantly higher in females than in males.
Noise exposure accelerates the heart rate by increasing blood flow in the arteries. There are two possible mechanisms that could explain hypertension from noise exposure. (1) Acute noise exposure can activate an immediate sympathetic reflex and then accelerate the development of structural changes in the cardiovascular system, ultimately resulting in sustained elevation of blood pressure. Stress related activation of neuroendocrine pathways through high cortisol levels can give rise to metabolic syndrome, resulting to hypertension and other cardiovascular effects.