Thursday, August 13, 2009

Inconvenient Smog? Nuisance Noise?

A report published in 2007 titled, Noise Pollution: A Modern Plague, reviews much of the literature on the subject and abstracts the findings to date.

I really like this quote:

Former U.S. Surgeon General William H. Stewart said in 1978, “Calling noise a nuisance is like calling smog an inconvenience. Noise must be considered a hazard to the health of people everywhere.”

... and these paragraphs from the Background section:

"Because their wheels clattered on paving stones, chariots in ancient Rome were banned from the streets at night to prevent the noise that disrupted sleep and caused annoyance to the citizens. Centuries later, some cities in Medieval Europe either banned horse drawn carriages and horses from the streets at night or covered the stone streets with straw to reduce noise and to ensure peaceful sleep for the residents. In more recent times in Philadelphia, the framers of our Constitution covered nearby cobblestone streets with earth to prevent noise-induced interruptions in their important work. These examples pinpoint two major effects of noise from which men in all ages have sought relief: interruption of sleep and interference with work that requires concentration...."

"(M)odern technology produce(s) increasing levels of unwanted noise of varying types and intensities throughout the day and night that disturb sleep, concentration, and other functions. This noise affects us without our being consciously aware of it. Unlike our eyes, which we can shut to exclude unwanted visual input, we cannot voluntarily shut our ears to exclude unwanted auditory input. Our hearing mechanisms are always “on” even when we are asleep."

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Adverse Health Effects of Noise are grouped into seven categories:

1. Hearing Impairment
2. Interference with Spoken Communication
3. Sleep Disturbances
4. Cardiovascular Disturbances
5. Disturbances in Mental Health
6. Impaired Task Performance
7. Negative Social Behavior and Annoyance Reactions:

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Selected excerpts, with emphasis added:

3. Sleep Disturbances: 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.

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

Other factors that influence the problem of night-time noise include its occurrence in residential areas with low background noise levels and combinations of noise and vibration such as produced by trains or heavy trucks [or icemaker compressors!]. Low frequency sound is more disturbing, even at very low sound pressure levels; these low frequency components appear to have a significant detrimental effect on health.

4. Cardiovascular Disturbances: A growing body of evidence confirms that noise pollution has both temporary and permanent effects on humans (and other mammals) by way of the endocrine and autonomic nervous systems. It has been postulated that noise acts as a nonspecific biologic stressor eliciting reactions that prepare the body for a “fight or flight” response. For this reason, 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. Studies of individuals exposed to occupational or environmental noise show that exposure of sufficient intensity and duration increases heart rate and peripheral resistance, increases blood pressure, increases blood viscosity and levels of blood lipids, causes shifts in electrolytes, and increases levels of epinephrine, norepinephrine, and cortisol. Sudden unexpected noise evokes reflex responses as well. Cardiovascular disturbances are independent of sleep disturbances; noise that does not interfere with the sleep of subjects may still provoke autonomic responses and secretion of epinephrine, norepinephrine, and cortisol. These responses suggest that one can never completely “get used to” nighttime noise.

Temporary noise exposure produces readily reversible physiologic changes. However, noise exposure of sufficient intensity, duration, and unpredictability provokes changes that may not be so readily reversible. The studies that have been done on the effects of environmental noise have shown an association between noise exposure and subsequent cardiovascular disease.

5. Disturbances in Mental Health: 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. Population studies have suggested associations between noise and mental-health indicators, such as rating of well-being, symptom profiles, the use of psychoactive drugs and sleeping pills, and mental-hospital admission rates.

6. Impaired Task Performance: The effects of noise pollution on cognitive task performance have been well-studied. Noise pollution impairs task performance at school and at work, increases errors, and decreases motivation. Reading attention, problem solving, and memory are most strongly affected by noise. Two types of memory deficits have been identified under experimental conditions: recall of subject content and recall of incidental details. Both are adversely influenced by noise. Deficits in performance can lead to errors and accidents, both of which have health and economic consequences.

7. Negative Social Behavior and Annoyance Reactions: Annoyance is defined as a feeling of displeasure associated with any agent or condition believed by an individual to adversely affect him or her. Perhaps a better description of this response would be aversion or distress. Noise has been used as a noxious stimulus in a variety of studies because it produces the same kinds of effects as other stressors. Annoyance increases significantly when noise is accompanied by vibration or by low frequency components. The term annoyance does not begin to cover the wide range of negative reactions associated with noise pollution; these include anger, disappointment, dissatisfaction, withdrawal, helplessness, depression, anxiety, distraction, agitation, or exhaustion. Lack of perceived control over the noise intensifies these effects.

Social and behavioral effects of noise exposure are complex, subtle, and indirect. These effects include changes in everyday behavior (e.g., closing windows and doors to eliminate outside noises; avoiding the use of balconies, patios and yards [and bedrooms!]; and turning up the volume of radios and television sets); changes in social behavior (e.g., aggressiveness, unfriendliness, nonparticipation, or disengagement); and changes in social indicators (e.g., residential mobility, hospital admissions, drug consumption, and accident rates); and changes in mood (increased reports of depression).

Noise exposure per se is not believed to produce aggressive behavior. However, in combination with provocation, preexisting anger or hostility, alcohol or other psychoactive agents, noise may trigger aggressive behavior. Our news is filled with examples of this kind of behavior.

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. Annoyance may be influenced by a variety of non-acoustical factors including individual sensitivity to noise. These include fear of the noise source, conviction that noise could be reduced by third parties, individual sensitivity, the degree to which an individual feels able to control the noise, and whether or not the noise originated from an important economic activity. 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.

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. In this regard, it is important to note that annoyance does not abate over time despite continuing exposure to noise.

Effects of Multiple Sources of Noise Pollution

Most environments contain a combination of sounds from more than one source (e.g., aircraft, motor vehicles, and trains). In urban environments, boom cars, car horns, car alarms, and public transit systems may be the offenders. In suburban areas, leaf blowers, other power equipment, and barking dogs may be the source. There is, as yet, no consensus on a model for measuring total annoyance from multiple noise sources. Adverse health effects appear to be related to total noise exposure from all sources rather than the noise from any single source.

The evidence related to low-frequency noise is sufficiently strong to warrant immediate concern. It is a special concern because of its pervasive nature, because it arises from multiple sources, and because of its efficient propagation, which is essentially unimpeded by conventional methods of either building or ear protection. Adverse health effects from low-frequency noise are thought to be more severe than from other forms of community noise. This form of noise is underestimated with the usual types of sound measuring equipment.

Conclusions and Recommendations

As a society, our history is filled with failures to recognize the agents that cause disease; once the causes have been recognized, we have responded reluctantly, slowly, and often inadequately. The case with tobacco is an instructive one. It took many years of lobbying by dedicated individuals before legislators and the general public recognized the links between the hazards of tobacco smoke and disease; as a result laws were finally enacted and behaviors changed accordingly.

Despite the evidence about the many medical, social, and economic effects of noise, as a society, we continue to suffer from the same inertia, the same reluctance to change, and the same denial of the obvious that the anti-tobacco lobby faced a couple of decades ago. This inertia and denial are similar to those that delayed appropriate action on lead, mercury, and asbestos. Now we seem unable to make the connection between noise and disease, despite the evidence, and despite the fact, which we all recognize, that our cities are becoming increasingly more polluted with noise.

Noise makers and the businesses that support them are as reluctant as smokers to give up their bad habits. Legislators at all levels should protect us from noise pollution the same way they protected us from tobacco smoke and other forms of pollution. It is clear that laws can change behaviors in ways that benefit society as a whole.

Noise represents an important public health problem that can lead to hearing loss, sleep disruption, cardiovascular disease, social handicaps, reduced productivity, impaired teaching and learning, absenteeism, increased drug use, and accidents. It can impair the ability to enjoy one’s property and leisure time and increases the frequency of antisocial behavior. Noise adversely affects general health and well-being in the same way as does chronic stress. It adversely affects future generations by degrading residential, social, and learning environments with corresponding economic losses. Local control of noise has not been successful in most places [especially Manteca!]. This points out the need for improved methods of local control that should include public education, enlightened legislation, and active enforcement of noise ordinances by local law enforcement officials. Part of the solution may require federal or state legislation aimed at supporting local efforts or the restoration of federal funding for the Office of Noise Abatement and Control.

Forty-six References are cited.

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