Dr. Louis Hagler was a resident of Marina Bay until train horns drove him away to the relative quietude of the Berkeley Hills last year. Before he left, however, he played a major role in establishing Richmond’s four railroad Quiet Zones, and he continues to meet with the Quiet Zone Task Group in hopes of establishing more. Dr. Hagler is an expert on the physiological and psychological harm that noise does to humans, and he has recently published a paper in the Southern Medical Journal that can be accessed at http://www.nonoise.org/library/smj/smj.htm.

Like childhood obesity, diabetes and asthma, the public health impacts of noise are hard for many to get excited about in a city plagued with homicides; however, the number of people adversely affected and the cumulative harm exceeds that of even our unacceptable homicide rate.

Like many cities, Richmond has laws against excessive noise, but they are not seen as a priority and are seldom enforced. The elimination of all train horns in Richmond is actually possible, but it will require the support of the City Council to fund grade crossing improvements and litigate against railroad companies.

Following are some questions and answers provided by Dr. Hagler about noise in an urban environment:

Why is environmental noise considered a form of pollution?

Pollution is the presence of harmful chemical, physical, or biological agents in air, water, food, or soil.  Pollutants adversely affect the health and well being of biological systems.  They do so either because they are present where they don’t belong or because they have reached a certain threshold level at which they begin to produce unwanted effects.  Most pollutants result from human activities.

Noise is a pollutant because it meets the two requirements of the definition.  It is a physical agent that can (and does) adversely affect the health and well being of biological systems.

Defining noise is not easy, because noise is unlike other pollutants in several important respects.  Most pollutants are substances that adversely affect health.  Noise is energy that adversely affects health.  Exposure to most pollutants is not perceived by the exposed individual.  Noise, however, produces a keen awareness of it presence.  Most pollutants create well defined physical effects on a single target organ or system.  Once perceived, noise produces both physical and psychological effects, the latter being the ones that are most readily apparent.  Lastly, noise is the only pollutant that can destroy its target organ (the organ of Corti).  The definition proposed by Kryter over 20 years ago still seems fitting.  Noise is audible, acoustical energy that adversely affects the physical or psychological well being of people.

This definition is consistent with the usual definition of noise as being “unwanted sound.”  I believe “unwanted” is an important part of the definition, since it describes the choice of the individual who hears the noise and is affected by it.  Other pollutants generally do not create an awareness of their presence in the same way that noise does.  When we hear sounds produced by others, to us they are second hand sounds.  Thus, noise can also be defined as any unwanted, second hand sound.

What are some common sources of environmental noise?

Noise pollution is an ancient problem.  In 45 BCE in Rome, the Julian Municipal Law banned chariot traffic at night because the wheels clattered on paving stones, disrupting sleep and annoying the citizens.  Juvenal (around the 1^st Century CE) wrote about the noise of carts going through the winding streets of ancient Rome.  He complained, “The sick die here because they cannot sleep.” 

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 of their important work.  These examples pinpoint two major effects of noise from which people in all ages have sought relief: interruption of sleep and interference with work that requires concentration.

The noises emanating from the various roadways of today are still among the most important sources of environmental noise, even though the types of noise are not the same as those that existed in Rome, Medieval Europe, or 18^th century Philadelphia.  Several recent studies have confirmed general traffic noise as the most frequent source of public annoyance.  Our modern roadways are traversed by motor vehicles of all types, by trains, and by aircraft.  These and other products of modern technology produce increasing levels of harmful noise of varying type and intensity throughout the day and night; noise that continues to disturb sleep, concentration, and other functions.   Much of the noise to which we are exposed may affect us without our being consciously aware of it, since our hearing mechanisms are always “on” and functioning, even when we are asleep.

The amounts and types of noise to which people are exposed today are greater than those experienced at any time in the past.  EPA research documented that noise levels in communities are directly related to population density. Thus, as the population grows, so does noise.  In addition to population growth, noise pollution continues to grow in extent, frequency, and severity as a result of progressive urbanization and an increasing number of highly mobile, powerful, and varied noise polluting devices.  

The noises to which we are exposed in our daily lives (excluding all those sounds in the workplace) come from more widespread and varied sources than ever before.  Some but not all of the noise falls below the level of our conscious awareness.  It is like the wallpaper on our walls, present but not really noticed.  Consider the noise pollution produced in and around our homes by garbage disposals, dishwashers, clothes washers and dryers, refrigerators, furnaces, air-conditioners, vacuum cleaners, yard maintenance equipment, and the many other mechanized time - and labor - saving devices, which we all use, rely upon, and in some cases tolerate, despite the noises they produce.  We and our children are exposed to the noise of radio, television, and related technologies.  Our children are exposed to a wide variety of noisy toys.  We are all exposed to the noise of internal combustion engines (modulated by legally required mufflers), jet engines (modulated by improved design and by altered flight paths), and train horns at grade crossings (modulated by new Federal Quiet Zone rules).  The sirens of emergency vehicles routinely shatter the silence, both day and night.

But that listing only begins to identify the countless sources of noise exposure.  Our children risk ear damage from the almost universal use of personal sound systems.  We are all bombarded by so-called boom cars (many with infants and children strapped into the back seat) that are little more than roving, pulsating, public address systems.  Excessively amplified sounds that are audible for great distances accompany boating excursions on rivers and lakes.  We are assaulted by uncomfortable sound levels at concerts, in theaters, and public sporting events.  We are forced to listen to the horns of slow moving trains in urbanized areas, the early morning sounds accompanying garbage collection, and the back up alarms on many larger vehicles.  Some have to contend with all the noise accompanying construction activities.  We have no choice but to hear the noise on our streets to which buses, trolley cars, automobiles, motorcycles, car horns, blaring car alarms, beeping, chirping and honking car locking systems, and un-muffled vehicular exhaust systems contribute.  Many of us are troubled by the noise of low flying aircraft.  The noise produced by neighbors is an almost universal urban problem; it is one that is growing in suburban and rural areas.  Many are annoyed by the ringing of cell phones and by their public use, allowing us to unwillingly eavesdrop on what should be private conversations; this is just one example that confirms unwanted sound does not have to be loud to be objectionable.  In addition to all the other sources of noise, those in suburban areas must tolerate barking dogs, leaf blowers, and various types of recreational vehicles. Some hear the sounds of gun clubs and shooting preserves.   Our society is beset by noise, which is intrusive, pervasive, and ubiquitous; most of it is unwanted and most important of all, it is unhealthy.  It is the effects on health that are at the heart of our concerns.

How does the body react to noise?

Auditory mechanisms are fully developed by the 24^th week of gestation; by the 26^th week, the fetus can perceive, react, and store auditory information.  Maturation of the auditory pathways in the central nervous system continues for several years after birth.

The healthy newborn demonstrates a significant reaction to noise.  Noise over 80 dB elicits a stress response that includes changes in respiratory, vascular, visceral, and motor systems.  Stress heightens autonomic responses leading to abrupt fluctuations in blood pressure, heart rate and oxygen saturation.  If stress from noise continues, the initial increases in cardiac and respiratory rates may disappear and the neonate may become bradycardic and apneic.  Thus, the neuroendocrine and cardiovascular responses to noise are established early in life and continue throughout the remainder of the individual’s life. 

In adults, awareness of the neuroendocrine and cardiovascular responses is often overshadowed by the psychological effects of noise, which will be covered in detail in the following paragraphs. 

Noise, even at levels that are not harmful to hearing, is perceived subconsciously as a danger signal, even during sleep.  The body reacts to this signal with a “flight or fight response” with resultant nervous, hormonal, and vascular changes that have far reaching consequences.  Noise is a stressor, producing the same kind of neuroendocrine and vascular responses that are produced by other forms of stress.  During the course of an ordinary day, the countless number of unwanted sound to which we are exposed contribute to the stresses of our modern society – stresses from which it is increasingly difficult to escape.  

What are some direct health consequences of noise pollution?

The World Health Organization has documented seven categories of adverse health effects of noise pollution on humans. In addition to these effects, noise is a   major source of recurring and often unrecognized stress, which, itself, degrades the quality of life and adversely affects health.

1. Hearing Impairment:  Hearing damage is related to duration and intensity of noise exposure and occurs at levels of 80 dB or greater, which is equivalent to the noise of heavy truck traffic.  Children seem to be more vulnerable than adults. 

2. Interference with Spoken Communication:  Noise pollution interferes with the ability to comprehend normal speech and may lead to a number of personal disabilities, handicaps, and behavioral changes.  These include problems with concentration, fatigue, uncertainty, lack of self confidence, irritation, misunderstandings, decreased working capacity, disturbed interpersonal relationships, and stress reactions. 

3. Sleep Disturbances:  Uninterrupted sleep is known to be a prerequisite for good physiological and mental functioning in healthy persons.  Noise pollution is a major cause of sleep disturbances.  Apart from various effects on sleep itself, noise pollution during sleep causes increased blood pressure, increased heart rate, increased pulse amplitude, vasoconstriction, cardiac arrhythmias, and increased body movement. These effects do not decrease over time.  Secondary effects include fatigue, depressed mood and well-being, decreased performance, and an increased frequency of accidents of all types.  Combinations of noise and vibration have a significant detrimental effect on health, even at low sound pressure levels. 

4. Cardiovascular Disturbances:  A growing body of evidence confirms that noise pollution is a risk factor for cardiovascular disease.  Acute exposure to noise activates nervous and hormonal responses.  If the exposure is of sufficient intensity, there is an outpouring of stress hormones (epinephrine, norepinephrine, and cortisol) leading to an increase in heart rate and peripheral resistance; an increase in blood pressure, and vasoconstriction. 

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.  Children, the elderly, and those with underlying depression are particularly susceptible to these effects.

6. Impaired Task Performance:  The effects of noise pollution on task performance have been well-studied.  Noise pollution impairs task performance, increases errors, and decreases motivation.  Reading attention, problem solving, and memory are most strongly affected by noise.  Noise produces negative after-effects on performance, particularly in children; it appears that the longer the exposure, the greater the damage.

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.  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.  Social and behavioral effects are complex, subtle, and indirect.   These effects include changes in everyday behavior (closing windows and doors to eliminate outside noises), changes in social behavior (aggressiveness or disengagement), and changes in social indicators (residential mobility, hospital admissions, drug consumption, and accident rates), and changes in mood (increased reports of depression).   Noise above 80 dB is consistently associated with decreased helping behavior and increased aggressiveness.

What are the other effects of noise pollution?

In addition to adversely affecting health and well being, noise pollution has significant social and economic effects. 

Some of the social effects have been discussed in the preceding paragraphs.   

Noise pollution has economic effects as well.  It is estimated that the costs associated with noise pollution range from 0.2 to 2.0% of a nation’s gross domestic product.  Noise pollution decreases the value of property, making it less desirable to own or live in.

In time of war, noise induced hearing loss becomes a significant issue for returning veterans.  In 1999, the United States paid over 291 million dollars to compensate affected veterans. With ongoing military actions today, one can safely assume that the amount of compensation will be substantially higher.

What are the sound thresholds in dB that cause negative impact?

This is an interesting area in which new and important data are emerging.  There is general agreement that exposure to noise levels below 70 dB is not harmful to hearing in adults, irrespective of duration of exposure.  As noise levels increase, permissible exposure times decrease.  At 80 dB, permissible exposure time is 8 hours.  According to NIOSH and the CDC, permissible exposure time falls to 15 minutes when noise levels reach 100 dB – a level produced by a power lawn mower or a boom car.

It is not possible to identify a precise decibel level of noise that disturbs sleep.  Disturbed sleep will depend on several factors including the difference between the noise event and the ambient noise level, the frequency (i.e., the number of cycles per second) and duration of the noise, and the age and sex of the individual.  To avoid negative effects on sleep, the World Health Organization recommends that continuous noise levels should not exceed 30 dB and that intermittent noise should not exceed 45 dB - and should be limited in number.  Noise induced disturbances of sleep have profound individual and societal effects.  At the individual level, disturbed sleep decreases alertness and disrupts circadian rhythms.  These lead to accidents, injuries, and death.  At the societal level, major catastrophic events such as the Three Mile Island, Bhopal, Chernobyl, and Exxon Valdez disasters occurred during the night shift.  Shift schedules, fatigue, and sleepiness were cited as major contributing factors in each incident.

There are a number of studies going back 30 years or more that demonstrate noise adversely affects the ability of children to learn, concentrate, and solve problems.  Cognitive functions of whole classrooms are affected by noisy environments.  These effects of noise may ultimately influence educational success, job opportunities, earning power, achievement of one’s goals, and satisfaction with life in general.

Within recent years, it has become increasingly apparent that noise produces a number of unwanted and potentially serious effects on the cardiovascular system.  Up to about 20 years ago, it was thought that adverse cardiovascular effects were seen with long-term daily exposure to noise levels above 65 dB or with acute exposure to noise levels above 80 to 85 dB.  Over the past 20 years, it has become apparent that these levels are too high; we now know that exposure to sound levels above 50 dB at night and 60 dB during the day may damage the cardiovascular system.  Such damage takes the form of high blood pressure, abnormal heart rhythms, and heart attacks.  A large scale review of several epidemiologic studies demonstrated a clear increase in the cardiovascular risk between 2000 and 2006.  A recently convened panel of experts in Europe concluded that 3% of all deaths from heart attacks were noise induced.  This makes noise induced heart disease a real and pressing public health issue.

According to the World Health Organization, noise levels above 80 dB are associated with both an increase in aggressive behavior and a decrease in behavior helpful to others.  The news media regularly report violent behavior arising out of disputes over noise; in many cases these disputes end in injury or death.

What research needs to be done on this topic?  Why is it difficult to demonstrate that chronic exposure to noise can produce illness?

Unlike other pollutants, noise produces physical and psychological responses, both of which are significant. For the most part, it is our psychological response that determines whether or not a given sound is deemed to be noise.  In contrast to other pollutants (which don’t produce a psychological response), the study of noise is more difficult because of its psychological component.

Noise is commonplace; it has been with us for centuries.  As time has passed, and as our society has become noisier, we have become more and more accustomed to it, so that, now, many consider it to be a “normal” part of our 21^st Century society.  It is not a new biohazard or technology that seems to be threatening, such as radiation, pesticides, or the AIDs virus.

Big business has effectively sold noise as a commodity.  The profit motives of big business (Sony, Pioneer, JBL, Harley Davidson, and others) have made noise an increasingly common part of our everyday existence.  Each of us, as individuals, contributes more or less to our noisy environment.  For those who are major contributors, regulation poses a threat of governmental intrusion and personal sacrifice, both of which seem contrary to current social norms. 

What efforts are underway to inform the public about environmental noise?

Many individuals across the United States take every possible opportunity to inform others about the hazards of noise.  They write their legislators and their newspapers about noise related matters.   Noise is newsworthy; the news media are filled with reports of citizen complaints about noise, of attempts to mitigate and control noise through more stringent noise laws,  and of noise related violence. 

There are numerous Internet sites that contain relevant information about noise and the ongoing efforts to restore quiet in communities across the United States.  For additional information about these sites, the interested reader should consult NoiseOFF (www.NoiseOFF.org), the Noise Pollution Clearinghouse (www.nonoise.org), Noise Free America (www.noisefree.org), Lower the Boom (www.lowertheboom.org), the Noise Abatement Society (www.noiseeabatementsociety.com), or the League for the Hard of Hearing (www.lhh.org/noise).  There are similar organizations around the world; two of the more active ones are the United Kingdom Noise Association (www.ukna.org.uk) and the Right to Quiet Society in Canada (www.quiet.org).