Environmental Stress And Health Research Paper

2. Definitions Of Environmental Stress

Although there are many different concepts of stress in the respective fields of medicine, psychology, and sociology, it is generally understood that stress is aversive in some sense. Psychologists often favor the stress concept proposed by Lazarus (1966), and Lazarus and Launier (1978), which defines stress as a transaction between stimulus and response, i.e., the process that reflects the individual appraisal of a stimulus by persons who see an imbalance between environmental demands and their own response capabilities to cope adequately with the demands. It should be noted that this concept relies heavily on individual self-reports, but sometimes even the individuals concerned do not notice the dangers that a certain situation provides for health, e.g., the potential hearing loss implied by loud music.

2.1 Characteristics Of Environmental Stressors

Environmental stressors are usually considered to fall into one of four distinct classes: cataclysmic events, stressful life events, daily hassles, and ambient stressors (Evans and Cohen 1987). Cataclysmic events comprise sudden catastrophes that affect many individuals at the same time. For instance, floods, major storms, earthquakes, volcanic eruptions, nuclear power plant accidents, chemical plant accidents, and the discovery of toxic waste dumps belong to this category. Cataclysmic events are seldom predictable, neither with respect to their beginning, nor with respect to their course, but they are usually expected to be rather short.

Stressful life events are major incidents in the course of life that require major individual adaptive responses. Such events include major changes in work, or residential environment, e.g., beginning a new job, moving to a new residential area, major construction work in the present residential area, or a major perceptible change in the operating conditions of a nearby stressor. The event as such is usually short, but the behavioral consequences may be long, or permanent.

Daily hassles are repeatedly occurring aversive events of ordinary life, such as arguments with colleagues, crowded classrooms, and traffic congestions on the daily route to work. Although they typically are more or less predictable, the individual has little means to avoid such hassles, and the duration is rather short.

Ambient stressors is a term proposed by Campbell (1983), denoting more continuous and intractable background characteristics of the physical environment. They often go unnoticed, like the continuous hum of the air conditioning, the permanent dust in an industrial area, and the faint hiss of the central heating system. Most people believe that they can adapt to ambient stressors, and they consider the costs of coping with such stressors to be higher than simply enduring them.

In addition, each type of environmental stressor can be categorized along several dimensions, of which we mention only three.

(a) The major dimension is the degree of controllability over the environmental stressor. Control may be either direct (e.g., switching off the neighbor’s noisy lawn mover), indirect (e.g., closing the windows in order to reduce the noise penetration), social (e.g., calling authorities to stop the noise), or cognitive (e.g., knowing that the noise will stop in about an hour). It has often turned out that stress effects decrease with increased control, but sometimes control has secondary stress effects (e.g., closing the windows will increase the temperature inside the house).

(b) Related to cognitive control is the predictability of the stressor. High predictability of the occurrence and time course of an aversive agent may help people to cope with it. For instance, residents in the vicinity of city rail systems usually know exactly the time schedule of the trains and seldom complain about noise and vibration, but they feel irritated when a train is missing. Alternatively, knowing beforehand that a new airport will open in the neighborhood does cause greater stress effects than knowing that the old airport will close in the neighborhood (Hatfield et al. 1998).

(c) Stressors may be more or less perceptually salient or identifiable. Some environmental agents are of rather low intensity and may either be not detected at all (e.g., low radioactive radiation), others are only detected when intensity changes (e.g., the faint current of air conditioners). If an environmental agent is not perceptually salient, stress reactions may occur because people get informed about potential hazards, and the type and degree of stress reaction depends very much on the content of information and the credibility of its source.

2.2 Variables Intervening Between Stressors And Their Effects

Although it is true that varying degrees of environmental load cause varying degrees of stress reactions in the average, it is also well known that the same degree of environmental load does not cause the same degree of reaction in every person or in every situation. It depends on situational, personal, and social variables whether an environmental agent becomes a severe problem for a person or not. For instance, a faint burning smell or a sudden noise may cause greater alarm reactions at night than the same events occurring during daytime—this is an example of situational moderation. Individual differences in susceptibility are well known with respect to noise and smoke, i.e., persons who judge themselves to be rather susceptible to noise generally show greater noise reactions than persons who judge themselves less susceptible. A similar relation holds for smoke, and recent evidence (Winneke and Neuf 1992) fosters the belief that environmental susceptibility is a general individual trait, comprising susceptibilities for different environmental agents.

While individual differences are thought to be the result of the individual development of a person, social intervening factors are thought to be the result of social developments, shared by larger groups of the society. For instance, a plant that emits fumes and noise may cause less stress effects when a group evaluates the source positively in some other respect (e.g., as providing jobs). Of course, there is no clearcut distinction between personal and social factors, because the individual development usually takes place within a certain society, and there is also a considerable individual variation with respect to sharing the views and evaluations of society in general. For an extensive discussion of moderating variables for noise, see Guski (1999).

3. Effects Of Environmental Stressors

3.1 Effects Of Noise

Noise is defined generally as unwanted sound, i.e., a sound that is already evaluated by somebody or some group as being aversive. Since the degree of aversiveness usually increases with the level of sound, the scientific study of noise effects is restricted to the middle and upper levels of environmental sound. Sound levels are usually given in decibels (e.g., dB), but care should be given to the exact meaning of the term used for describing the sound level. For instance, a temporary maximum value of L_max=65 dB is easily reached by every speaker at 1m distance—it may be a nuisance, but will cause no harm—while the sound energy of L_Aeq =65 dB calculated for 16 hours of daytime is considered to be a risk for health. The main source of environmental noise-effect studies is transportation noise (road, rail, and air), because it affects almost everybody in the industrialized world. Lambert and Vallet (1994) estimated 20 percent of citizens of the European Community to be exposed to transportation noise with daytime levels of L_Aeq=65 dB or higher.

The studies considered in this research paper are interdisciplinary field studies, using residents in the vicinity of traffic routes as subjects. The noise level is usually given as daytime and/or night-time sound energy, calculated from data about traffic volumes, together with a few supporting measurements at the outside of the subjects’ lodgings. The questionnaires usually cover noise-effect questions (e.g., with respect to annoyance, disturbance of communication, disturbance of recreation, and sleep quality) in a closed response format, general questions about living conditions, demographic characteristics, and potential intervening variables, such as the individual noise sensitivity, health status, coping capacity, and trust/distrust in authorities of the sound source. Daytime environmental traffic noise has large statistical effects on the degree of annoyance, and the degree of reported disturbances of daily activities. Nighttime environmental traffic noise has somewhat smaller statistical effects on the degree of general annoyance and reported sleep quality. A very typical result is the linear relationship between physical parameters of sound and the mean response of residents, at least as far as raw scores are used. Sometimes, the responses are given as percent ‘highly annoyed’ (percent HA), selecting only those residents who chose the upper 27 percent of the original scale. Because of the selection process, the dose–response curve is nonlinear in that case. A typical dose–response relationship is given in Fig. 1, showing the nonlinear relationship between the level of daytime aircraft noise in the residential area, and the average percentage of residents who say that they are disturbed while engaged in different activities during the day.

In comparing the effects of different sources of transportation noise, it is generally found that the mean general annoyance response is somewhat higher for aircraft noise than for road traffic and railroad noise at the same overall noise levels, if the noise levels are converted to day night levels (Ldn), where night levels are weighted 10 dB stronger than day levels (Miedema and Vos 1998). The same authors (1999) conclude from a comparison of original data from several studies that personal attitudes to noise (e.g., fear or other negative evaluations of the source, and noise sensitivity) are very effective variables intervening between the physical impact and the annoyance response to noise.

With respect to somatic effects of noise, data are less clear, but there are several studies showing the prevalence of ischemic heart diseases to increase somewhat in middle-aged males with high levels of daytime road traffic noise (Babisch et al. 1999). Under nighttime transportation noise a fragmentation of the sleep structure is to be observed and can be classified as stress (Griefahn 1986, Griefahn and Muzet 1978). The effects can be observed by means of individual EEG recordings during the night, as well as by means of increased fallout of the stress hormones adrenaline, noradrenaline, and cortisol. Maschke et al. (1998) claim that an increased secretion of adrenaline and noradrenaline belongs to a defense situation, an increased secretion of cortisol marks a defeat situation. The results of an experimental longitudinal field study at Hamburg Airport show no uniform cortisol excretion reaction to persistent aircraft noise, but about half of 16 subjects display an increased cortisol excretion after a phase of adaptation during the disturbed night, and the increased cortisol levels are classified as exceeding the normal range.

3.2 Living On Polluted Soil

Residential areas are sometimes built in the vicinity of former industrial areas, and this can cause severe problems for health, if the soil is polluted. One of the best known examples is Love Canal (see Bell et al. 1995), where toxic agents had been disposed of over years into a creek, and several years after the closure of the chemical plant, residential buildings were erected in the area. When toxic evaporations were detected, health authorities alarmed the residents and offered financial help for those who wanted to move. The monetary compensations were judged to be insufficient by many residents, and a long-lasting public debate reflected the severe helplessness of many residents (Levine 1982).

Another example is a residential area in Dortmund (Germany), where toxic evaporations from a former chemical plant were detected and caused severe psychosomatic complaints (Matthies et al. 2000). The debate about possible health hazards, in combination with insensitive communication policy of the health authorities, led to ongoing psychosomatic effects even after the beginning of a complete soil exchange in the whole residential area. The amount and degree of complaints was not related to any chemical variable measured, but differed significantly from a control group in an unpolluted area.

3.3 Living With Nuclear Power Plants

Although the nuclear industry spends billions of dollars for public relations in the hope of changing public attitudes to nuclear power plants and nuclear waste, the general attitudes in Western societies seem rather skeptic. The skeptic attitudes are caused by the public experience of technological catastrophes like Three Mile Island (TMI) (1979) and Chernobyl (1986). The psychological effects of technological catastrophes on residents differ from those of natural hazards in many ways, e.g., they are more long lasting, and residents lose faith in public communications of authorities with respect to safety and control of health risks. Even seven years after the catastrophe at TMI, residents living near the damaged reactor reported more chronic stress symptoms and sleep disturbances than did control subjects (Davidson et al. 1987).

The catastrophe at Chernobyl caused severe psychological changes in the European population, especially with respect to the evaluation of nuclear power, the probability of a nuclear accident, and the health risks for children (Drottz-Sjoberg and Sjoberg 1990, Huppe and Janke 1994). Many social scientists believe that the inconsistent and reluctant communication policy of public authorities has contributed to the stress symptoms of residents who were only slightly exposed to direct nuclear radiation.

4. Conclusions

Environmental characteristics of residential areas (such as noise, polluted soil, and nuclear power plants) may lead to disturbances of intended behavior, psychological and physiological discomfort, and health aspects of residents. The relation between physical characteristics of the source and the aversive reactions can be described as a stress situation, because the reactions covary with the degree of emission, and residents usually cannot stop the emissions of the source directly. In addition, situational, personal, and social variables moderate the dose-response relationship.

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