Effects of Noise Pollution on Stress Levels in the Dominican Republic
Michigan State University
CIC 2006: Issues of Health, Nutrition, and
Environment in Latin America
Noise is defined as an invisible pollutant that studies have linked to hypertension and disturbed sleep, which are also known to be health effects of stress. The correlation of noise pollution with stress levels, however, is a topic that has been overlooked in research. This study evaluated noise pollution and its effect on stress levels and identified the major sources of noise in the Dominican Republic. Thirty residents living in the countryside, a town, and city participated in this study. Each subject completed two questionnaires concerning stress and noise factors. In the city, a correlation of 0.6703 between noise and stress factors was found to be greater than the correlation between the Life Stress Questionnaire and stress factors, 0.2945. From this, it was concluded that stressors other than noise did not contribute to the measured stress levels and that a high level of noise pollution negatively affects stress levels. The results from the other two sample sites were inconclusive. In addition, motorcycles and music were found to be the major sources of noise. For future studies, a more accurate means of measuring stress and noise would provide better results.
El ruido es definido como un contaminante invisible que investigaciones han unido a hipertensión y sueño molestado, el cual es también conocido como efectos de estrés. La correlación del ruido con los niveles de estrés es un tema que ha sido pasado por alto en investigaciones. Este estudio evaluó el ruido y su efecto sobre los niveles de estrés e identificó las mayores fuentes de ruido en la República Dominicana. Diez sujetos del campo, diez de un pueblo, y diez de una ciudad participaron en este estudio. Cada sujeto llenó dos cuestionarios sobre de estrés y ruido. En la ciudad, una correlación de 0.6703 entre los factores del ruido y el estrés fue encontrado a estar mayor que la correlación entre el control, 0.2945. Los resultados de este estudio descubrieron que los niveles altos de ruido tenían un efecto negativo sobre los niveles de estrés. Los resultados de otros lugares muestras fue inconcluso. También, este estudio descubrió que las mayores fuentes de ruido son las motocicletas y la música. Para las investigaciones en la futura, un medio más exacto para medir el estrés y el ruido facilitaría resultados mejores.
The word noise was first recorded around the beginning of the 13th century. It is thought to be traced back to the Latin word nausea, meaning “seasickness, feeling of sickness.” Today, the word noise is defined as an invisible pollutant that studies have linked to hypertension and disturbed sleep, which are also known to be health effects of stress. However, correlating noise pollution with stress levels is a topic that has been overlooked in research. This study will evaluate noise pollution and its effect on stress levels as well as identifying the major sources of noise in the Dominican Republic. It is hypothesized that noise will have a negative impact on stress levels.
Noise is the pollution of hearing with disturbing and unsolicited sound. Studies have found that this form of pollution is not only an annoyance, but also harmful to one’s health (Weinhold, 2002). One of the leading causes of permanent hearing damage is excessive noise (Blanchard, 1998). One study found that noise exposure may shift ones hearing threshold, which may result in the loss of hearing (Schneider, 1976). For example, the firing of a gun may cause a person to be temporarily deafened by a loud noise. This temporary deafness, known as Temporary Threshold Shift, is often accompanied by ringing in the ears (Bugliarello, 1976). Moreover, this noise exposure does not necessarily need to be loud to cause hearing loss (Blanchard, 1998).
Noise is calculated in units called “decibels” which measures how much pressure is created by the sound wave producing the sound (California-Arizona). The range of decibels is from zero to about 140, which is approximately the smallest sound human ears can hear to the sound level that will do damage to the ear (California-Arizona). Exposure of eight hours of more per day to sound levels of about 85 decibels, for example heavy traffic or a noise restaurant, will result in a loss of hearing after many years (Chouard, C.H., 2001). The Occupational Safety and Health Agency has set the danger level of noise exposure at 95 decibels and above for four or more hours per day (Nunez, 1998). This decibel level is equivalent to the sound emitted by a motorcycle (Noise Center of the League). However, noise less than 75 decibels could be linked to hypertension (Akin, 2004). A study performed by Peterson et. al confirmed this as they found that noise could produce sustained elevations in blood pressure, which did not return to baseline values after the noise ended. It was also found that noise is safe if it has no effect on one’s hearing threshold (Passchier-Vermeer, 2004).
In a study done by Berglund, 1999, sleep disturbance was found to be a major effect of environmental noise. They found noise was among the causes of sleep disturbance. Decibel levels for a good night’s sleep should not exceed 30 decibels, which is equivalent to a soft whisper (Manuel, 2005; Noise Center of the League). In the Berglund et.. al, study other physiological effects were also noted during sleep such as increased heart rate, increased blood pressure, and an increase in body movements. There has also been recent research of the effects of exposure, awareness, and annoyance reactions to aircraft noise on sleep disturbance (Graeven, 1974). Research performed close to London’s Heathrow airport indicated that the amount of people awakened by airplanes is approximately 50% greater than the number of awakened by other noises (Holland-Wegman, 1967). Aircraft and vehicle traffic are two of the largest sources of noise that increase at a rate of three to five percent annually (Blanchard, 1998). A study done by the US Environmental Protection Agency in 1980 found that among the sources of noise, motorcycles were the number one source followed by automobiles and large trucks (Nunez, 1998). Disturbed sleep is a consequence of noise pollution that has been found to affect stress (Kirmil-Gray et. al, 1984).
The definition of stress varies from person to person. It can be defined as an experience that causes one to feel tension, pressure, and lead to physiological changes such as increased heart rate and muscle tension. Stressors, or situations that initiate stress, may include traffic jams, work, or the death of a loved one. Situations like these may overwhelm a person’s ability to cope and function properly, causing them to feel stressed. Prolonged or excessive stress can result in stress-related illnesses such as irritable bowel syndrome or chronic headaches (Frey, 2002). Researchers from the Ohio State University found the immune system to be negatively affected by stress (Glaser & Kiecolt-Glaser, 2005). In their study, they found that stress could disrupt the process of wound healing and lead to a faster progression of AIDS among HIV-infected men. However, stress is an essential and healthy part of life (Franklin, 2004). For example, it releases norepinephrine, a principle excitatory neurotransmitter that improves mood and is needed to create new memories (Franklin, 2004).
Stress can also be defined as an unpleasant state of emotional and physiological stimulation that one experiences in situations that is perceived as dangerous or threatening to their well-being. Many of these situations are heralded by loud noises such as the screaming of child and the wailing of a siren (Franklin, 2004). This instinctual reaction to noise allows us to go from a deep slumber to a quick dash in a matter of seconds (Franklin, 2004). In today’s world, this instinctual reaction is triggered by car alarms or car stereo systems, contributing to the stress on ones health (Franklin, 2004). Emotionally, feelings of depression, anxiety, and anger can be brought on by stress (McEwen & Stellar, 1993). An example of this is posttraumatic stress disorder (PTSD), an enduring and distressing emotional ailment that precedes exposure to a severe helplessness or fear inducing threat (Wu & Perdomo, 2004).
Stress, as well as its debilitating effects, can be managed through relaxation and physical activity (Bratcher, 2006). People react to and cope with stress in several ways, but if left unmanaged it can lead to cardiovascular disease and gastrointestinal problems (Nilsson-Weiskott, 2001). Recent studies have linked stress to high health care costs (HeartMath, 2002; Manning et. al, 1996). According to the American Institute of Stress, it is estimated that 75% to 90% of visits to the doctor are stress-related (HeartMath, 2002). Workforce magazine estimated that seven of the top ten selling drugs worldwide are either anti-depressant or anti-ulcer medications, with stress as a primary factor in the need for both (HeartMath, 2002).
Linking Noise to Stress
Noise pollution is an issue that has been overlooked in research. The few studies performed have found that noise pollution negatively affects one’s health. These include permanent hearing damage and an increase in blood pressure (Blanchard, 1998; Peterson et. al, 1981). In addition, noise has been found to affect stress indirectly because of its negative impact on sleep (Berglund, 1999). In recent years, stress has been blamed for the high cost of healthcare (HeartMath, 2002). Thus, noise pollution and stress are two subjects that affect health and healthcare. However, very few studies have been conducted on the relationship between noise and stress. This study will investigate the effect noise pollution has on stress levels and identify the major sources of noise in the Dominican Republic.
The subjects included ten residents of Jarabacoa, a town of about 52,000 people, ten residents of Santiago, a city with a population of about 501,800, and ten residents living in a rural campo, Capilla, located in the northeast region of the Dominican Republic. These three areas were chosen in order to determine the effect of increasing noise on stress levels, with the noise intensity designated as low, medium, and high for campo, town, and city, respectively. Among the ten residents from each area of study, five were females and the other five were males. The age of the subjects ranged from 21 to 73. The subjects interviewed were randomly chosen near the noisiest areas in each study site.
This exploratory research was conducted according to the guidelines set forth by the U.S. Institutional Review Boards regarding human subjects research carried out specifically for education programs. Data was collected using a quantitative method where the subjects were asked questions off two sets of questionnaires. They were first asked 16 questions, 10 of which were of Likert format, from a noise pollution questionnaire. The noise questionnaire also contained questions concerning noise (questions 3, 5, 7, 11, and 15) and stress symptoms related to noise (questions 6, 9, and 10) (Appendix B). Thus, this questionnaire evaluated how noise pollution affects subjects’ daily lives, stress levels and exposure to noise in their place of residence.
The second questionnaire, a life stress questionnaire (LSQ) from the Wisconsin Department of Workforce Development, required them to identify stressors in their life (Appendix C). This questionnaire was used to control for other stressors not related to noise. The questionnaire included 34 stressors such as tension at work, changes in sleeping habits, and the loss of a loved one. Each stressor is assigned a number value that is used to measure each subject’s stress level when added up. The data obtained from the questionnaires were recorded using Microsoft Excel.
Scatter plots for results of these two questionnaires were made using Microsoft Excel. Two comparisons were made for each study site: one comparing results of the LSQ to stress levels caused by noise and the other comparing noise effects and stress levels. Correlations were determined and recorded using Microsoft Excel. Noise was determined to affect stress if a higher correlation was noticed for that between noise effects and stress levels than that of the LSQ to stress levels caused by noise.
The results from this study confirm the hypothesis that noise pollution, of high levels, has a negative effect on stress levels for the study sample in Santiago. Table 1 shows music, motorcycles, and cars as the most common sources of noise at each study site. They were also the most common noises that cause disturbed sleep according to the data in table 2. Subjects reported little or no usage of sleeping pills or tranquilizers as a sleep aid. Headaches and hypertension are the most common health problems among the interviewed subjects in all locations, as shown in table 3.
Table 1. Sources of Noise. The information in this table ranks the most common sources of noise at the different areas of study.
Area of Study
Sources of Noise
1. Music 2. Cars
1. Motorcycles 2. Music
1. Music 2. Motorcycles
Table 2. Noises Causing Disturbed Sleep. This table depicts the most common noises that cause disturbed sleep in the different areas of study. This data was obtained from the noise pollution questionnaire.
Area of Study
Sources of Noise
Table 3. Chronic Health Problems. The data in this table reveals the most common health problems at each area of study. This information was obtained from the noise pollution questionnaire.
Area of Study
Chronic Health Problem
The results from the Life Stress Questionnaire, noise, and stress factor questions can be viewed in tables 4 to 6. These values were used in calculating the data in table 7, which shows the correlation between the noise factor questions and the stress factor questions for each study site. The values in tables 4-6 were used to calculate the data in table 7.
Table 4. Campo Questionnaire Results. This table displays the scores obtained during the campo study from the two questionnaires. These values were used in calculating the correlations in table 7. Two outlying points, subjects 2 and 4, were removed from the study.
Table 5. Jarabacoa Questionnaire Results. This table shows the scores acquired during the Jarabacoa study from the two questionnaires. These values were used in calculating the correlations in table 7.
Table 6. Santiago Questionnaire Results. These values were used in calculating the correlations in table 7.
Table 7. Questionnaire Correlations. The information in this table shows the effect noise has on stress levels. The data was calculated from the values in tables 4-6.
Area of Study
Noise Factors vs. Stress Factors
Life Stress Questionnaire vs. Stress Factors
Of the three study sites, the effect noise has on stress levels was found to be the greatest in Santiago with a correlation of 0.6703. In the campo and Jarabacoa, the correlations between the Life Stress Questionnaire and stress factors were calculated to be 0.4116 and 0.4174. The control, the correlations between the Life Stress Questionnaire results with the stress factor questions, can also be seen in this table. These correlations can be seen in figures 1 to 3.
Subjects from Santiago showed the lowest tolerance for noise, followed by the campo and Jarabacoa. This trend can be seen in question 13 of appendices D, E, and F.
As it was mentioned earlier, our main purpose of this investigation was to determine if noise has a negative impact on stress levels. In the case of Santiago, the area of study with the highest level of noise pollution, the hypothesis is confirmed. Among the three study sites, the effect noise has on stress levels was found to be the greatest with a correlation of 0.6703 in the Santiago study sample. Because this number is greater than the correlation between the Life Stress Questionnaire and stress factors, 0.2945, stressors other than noise did not contribute to the measured stress levels. This correlation agrees with the finding that the Santiago subjects had the lowest tolerance for noise. In addition, the chronic health problems shown in table 3 may have been an influence. Headaches and hypertension are known to be effects of noise but also causes of stress. The results from the other study sites were inconclusive. For the campo and Jarabacoa, the correlations between the Life Stress Questionnaire, 0.4116 and 0.4174, were greater than the correlations between the noise factors and stress factors, 0.2957 and -0.5439. This indicates that stressors other than noise contributed to the measured stress levels or the level of noise was not enough to affect stress levels. However, the subjects may have had high tolerance for noise. Subjects showed high tolerance for noise in respect to stress levels. Yet, subjects claimed that noise does affect stress levels. This trend can be seen in appendices D-F, questions 11 and 12.
The language barrier is among the limitations of this study. The questionnaires, which were originally written in English, may not have been translated correctly into Spanish. This may have led to the misinterpretation of the questions and which might have produced the outlying points seen in table 4. Other limitations of this study include the small pool of subjects and the area of which subjects were interviewed may be louder or quieter than others.
The purpose of this study was to confirm the hypothesis that noise pollution will have a negative impact on stress levels and identify the sources of noise in the Dominican Republic.
This study was successful in linking noise with stress in the Santiago study sample. Results from the campo and Jarabacoa were inconclusive.
In addition, the major sources of noise were identified as music, motorcycles, and cars. This study could be improved with a larger subject pool and the use of an English-Spanish translator. It could also be improved with a more accurate means measuring stress and noise.
Noise Pollution & Life Stress Questionnaire
The purpose of this study is to investigate noise pollution and its effect on stress levels. The only personal identifiers recorded for this study will be age and gender. Your participation in this study is greatly appreciated as it will help in correlating noise pollution with stress levels and serve as reference for future studies.
Noise Pollution & Stress Questionnaire
Please answer the following questions to the best of your ability. Many of the questions utilize a number scale where a number answer is required.
1) How old are you?
2) For how long have you lived in (Jarabacoa/Santiago/the campo)?
3) Do you think that noise is a problem where you live?
[1(not a problem) 2 3 4 5(big problem)]
4) What are the sources of noise where you live? For example motorcycles, roosters, or loud music.
5) When you hear a loud noise, for example a passing motor cycle, how do you feel?
[1(not bothered) 2 3 4 5(very bothered)]
6) Do you sleep well each night?
[1(very well) 2 3 4 5(bad)]
7) Is your capacity to sleep effected by noise?
[1(no) 2 3 4 5(a lot)]
If yes, by which type(s) of noise?
8) Because of noise, are there times when you use sleeping pills or tranquilizers to sleep?
[1(never) 2 3 4 5(many times)]
9) Do you have chronic health problems? For example, hypertension, indigestion, headaches, anxiety, or depression.
10) Do you think these problems are agitated by noise?
[1(no) 2 3 4 5(a lot)]
11) How would you estimate your level of stress?
[1(low) 2 3 4 5(high)]
12) Do you think that your stress is agitated by noise?
[1(no) 2 3 4 5(a lot)]
13) Do you think that noise effects stress levels?
[1(no) 2 3 4 5(a lot)]
14) Until what point does noise bother you?
[1(low) 2 3 4 5(high)]
15) How many hours do you sleep each night?
16) Does noise affect this number?
[1(no) 2 3 4 5(a lot)]
17) Is your sleep interrupted by noise because it wakes you up, it impedes your sleep, both, or neither.
Your participating in this study is greatly appreciated.