Noise is defined as unwanted sound.

 

Noise pollution is an often-overlooked source of environmental stress that can raise your risk of serious health conditions, including heart disease.

Just how much noise a person can reasonably handle without health consequences is still relatively unknown… but what is clear is that excess noise is a serious risk factor for your health. 

Noise Pollution and Air Pollution Often Go Hand-in-Hand. Those who live near busy roadways, airports, and industrial areas are those most likely to be exposed to both noise pollution and air pollution.

Interestingly, both fine particle matter of air pollution and noise pollution are believed to increase your cardiovascular disease risk through similar biologic pathways, including by causing an imbalance in your autonomic nervous system (ANS).

The WHO has documented categories of adverse health effects of noise pollution on humans. Noise-Induced Hearing Loss. Hearing impairment is typically defined as an increase in the threshold of hearing as clinically assessed by audiometry.

The major cause of hearing loss is occupational exposure, although other sources of noise, particularly recreational noise, may produce significant deficits.

Noise-induced hearing loss (NIHL), can occur from one very loud noise exposure (such as an explosion) or continuous exposure to loud noise over time (such as working in a factory). 

Recreational activities that can put you at risk for NIHL include target shooting and hunting, listening to MP3 players at high volume through earbuds or headphones, playing in a band, and attending loud concerts. 

Harmful noises at home may come from sources including lawnmowers and woodworking tools. Those working in clubs, bars, and other places of entertainment are also at risk. It is well known that rock musicians frequently have noise-induced hearing loss.

Apart from the musicians themselves, employees of music clubs, where noise frequently exceeds safe levels, are at risk. 

WHO recommends that unprotected exposure to sound levels greater than 100 dB (for example, the sound of a jackhammer) should be limited in duration (4 h) and frequency (four times/yr).

Firecrackers and other toys can generate sufficient sound levels to cause sudden and permanent hearing loss. Levels greater than 165 dB, even for a few milliseconds, are likely to cause acute cochlear damage.  

Sound is measured in units called decibels. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. 

There is also general agreement that exposure for more than 8 hours to sound levels in excess of 85 dB is potentially hazardous; 85 dB is roughly equivalent to the noise of heavy truck traffic on a busy road.

 

Long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen. Here are the average decibel ratings of some familiar sounds:

The humming of a refrigerator: 45 decibels

Normal conversation: 60 decibels

Noise from heavy city traffic: 85 decibels

Motorcycles: 95 decibels

An MP3 player at maximum volume: 105 decibels

Sirens: 120 decibels

Firecrackers and firearms: 150 decibels

Your distance from the source of the sound and the length of time you are exposed to the sound are also important factors in protecting your hearing.

A good rule of thumb is to avoid noises that are too loud, too close, or last too long. Studies suggest that children seem to be more vulnerable than adults to noise-induced hearing impairment. 

Noise-induced hearing impairment may be accompanied by abnormal loudness perception (loudness recruitment), distortion (paracusis), and tinnitus.

Tinnitus may be temporary or may become permanent after prolonged exposure.  The best way to prevent NIHL is to reduce the noise if possible, and if not wear earplugs or other protective devices to protect your hearing.

If you can’t do either of these, move away from the noise. How Does Noise Pollution Harm Your Heart? Long-term exposure to traffic noise may account for approximately 3 percent of coronary heart disease deaths (or about 210,000 deaths) in Europe each year. 

But how exactly does noise harm your heart?

One of the key ways is by elevating stress hormones such as cortisol, adrenaline, and noradrenaline, which, over time, can lead to high blood pressure, stroke and heart failure.

Arousal associated with nighttime noise exposure increased blood and saliva concentrations of these hormones even during sleep.

Noise is a major stressor that can influence health through the endocrine, immune, and cardiovascular systems.

Noise can trigger both endocrine and autonomic nervous system responses that affect the cardiovascular system and thus may be a risk factor for cardiovascular disease.

These effects begin to be seen with long-term daily exposure to noise levels above 65 dB or with acute exposure to noise levels above 80 to 85 dB. Acute exposure to noise activates nervous and hormonal responses, leading to temporary increases in blood pressure, heart rate, and vasoconstriction.

 

Noise pollution interferes with the ability to comprehend normal speech and may lead to a number of personal disabilities, handicaps, and behavioural changes.

These include problems with concentration, fatigue, uncertainty, lack of self-confidence, irritation, misunderstandings, decreased working capacity, disturbed interpersonal relationships, and stress reactions.

Some of these effects may lead to increased accidents, disruption of communication in the classroom, and impaired academic performance. 

Particularly vulnerable groups include children, the elderly, and those not familiar with the spoken language. 

Sleep disturbance. Uninterrupted sleep is known to be a prerequisite for good physiologic and mental functioning in healthy individuals. 

Environmental noise is one of the major causes of disturbed sleep. When sleep disruption becomes chronic, the results are mood changes, decrements in performance, and other long-term effects on health and well-being.

It is known, for example, that continuous noise in excess of 30 dB disturbs sleep. For intermittent noise, the probability of being awakened increases with the number of noise events per night. 

The primary sleep disturbances are difficulty falling asleep, frequent awakenings, waking too early, and alterations in sleep stages and depth, especially a reduction in REM sleep.

Apart from various effects on sleep itself, noise during sleep causes increased blood pressure, increased heart rate, increased pulse amplitude, vasoconstriction, changes in respiration, cardiac arrhythmias, and increased body movement. 

Secondary effects (so-called after effects) measured the following day include fatigue, depressed mood and well-being, and decreased performance.  

 

Mental illness. Noise pollution is not believed to be a cause of mental illness, but it is assumed to accelerate and intensify the development of latent mental disorders.

Noise pollution may cause or contribute to the following adverse effects: anxiety, stress, nervousness, nausea, headache, emotional instability, argumentativeness, sexual impotence, changes in mood, increase in social conflicts, neurosis, hysteria, and psychosis.

Children, the elderly, and those with underlying depression may be particularly vulnerable to these effects because they may lack adequate coping mechanisms. 

Noise levels above 80 dB are associated with both an increase in aggressive behaviour and a decrease in behaviour helpful to others. Cognitive task performance.

Noise pollution impairs task performance at school and at work, increases errors, and decreases motivation. Reading attention, problem-solving, social and emotional development, and memory are most strongly affected by noise.

Deficits in performance can lead to errors and accidents, both of which have health and economic consequences. 

These findings suggest that more attention needs to be paid to the effects of noise on the ability of children to learn and on the nature of the learning environment, both in school and at home.  

Social and behavioral effects of noise exposure are complex, subtle, and indirect.

These effects include changes in everyday behaviour (e.g. closing windows and doors to eliminate outside noises; avoiding the use of balconies and yards; and turning up the volume of radios and television sets); changes in social behaviour (e.g. aggressiveness, unfriendliness, nonparticipation, or disengagement..

Noise exposure per se is not believed to produce aggressive behaviour. However, in combination with provocation, preexisting anger or hostility, alcohol or other psychoactive agents, noise may trigger aggressive behaviour.                    

Annoyance. This is defined as a feeling of displeasure associated with any agent or condition believed by an individual to adversely affect him or her. 

Annoyance increases significantly when noise is accompanied by vibration or by low frequency components.  

The degree of annoyance produced by noise may vary with the time of day, the unpleasant characteristics of the noise, the duration and intensity of the noise, the meaning associated with it, and the nature of the activity that the noise interrupted.  

Other less direct effects of annoyance are disruption of one's peace of mind, the enjoyment of one's property, and the enjoyment of solitude.

 Sound levels produced by the average refrigerator or the sounds in the typical quiet neighbourhood measure about 45 dB. Sound levels above this produce annoyance in significant numbers of people.

The results of annoyance are privately felt dissatisfaction, publicly expressed complaints to authorities (although underreporting is probably significant), and the adverse health effects already noted.

Given that annoyance can connote more than slight irritation, it describes a significant degradation in the quality of life, which corresponds to degradation in health and well-being.

Long-term psychosocial effects have been related to nocturnal noise. Noise annoyance during the night increases total noise annoyance for the following 24 hours.

Particularly sensitive groups include the elderly, shift workers, persons vulnerable to physical or mental disorders, and those with sleep disorders.