Multiple environmental burdens and neighborhood-related health of city residents

Abstract

Urban living environments are known to influence human well-being and health; however, little is known about the multidimensionality of different environmental burdens. The aim of this study is to examine the relations between multiple burdens and self-rated health of city residents in Berlin. A spatial analysis was conducted to determine neighborhood street blocks with high versus low levels of three environmental burdens (traffic noise, air pollution, lack of public green space) as study sites for a cross-sectional household questionnaire. Burden level served as a dichotomous predictor to compare residents' self-reports of neighborhood satisfaction, life satisfaction, health behavior, and psychological and physical health symptoms. Residents from high-burden blocks appraised the environmental conditions more stressful, reported poorer health behavior and were less satisfied with their neighborhood than residents from low-burden blocks. However, they did not differ in regard to more general health symptoms. Three other burdens (behavior-related noise, litter and dirt in public space, lack of urban vegetation), which could not be varied objectively, were assessed by their perceived intensity. Regression analyses of the relations between the perceived levels of all six burdens and outcomes in the total sample revealed the following: Neighborhood satisfaction could be predicted from multiple stressors and resources that co-occur independently, while more general health symptoms were related only to perceived air pollution. The results have implications for both urban planning and public health.

Introduction

In the light of rapid world-wide urbanization processes, current public debate and research in multiple disciplines focuses on how to design, develop and manage cities sustainably so as to provide city dwellers with health-supportive habitats. According to the World Health Organization's definition of health (World Health Organization, 1946), urban neighborhoods must ensure not only the absence of disease or infirmity, but also support a state of complete physical, mental and social well-being.¹ Improving habitats within dense urban areas implies the use and increase of benefits from ecosystem services, as well as the reduction of pollution and environmental burdens (Bolund & Hunhammar, 1999; Endlicher et al., 2011). To date, the dominant research approaches have focused on health effects of singular environmental resources (i.e., potentially beneficial factors) or burdens (i.e., potentially harmful factors) and/or on singular levels of inquiry (e.g., individual, neighborhood, community). However, the demand for comprehensive research integrating multiple factors and multiple-level approaches to better understand the complexities of environmental factors has recently increased (cf. Galea, Freudenberg, & Vlahov, 2005). Consequently, the present paper aims at an integrative understanding of the relations between urban environmental stressors and resources, and neighborhood-related health. After presenting the existing theoretical approaches and empirical results from both research perspectives (environmental stress and environmental resources), we develop an integrative framework that we apply to our empirical study.

Many of today's urban environmental burdens that influence human health can be subsumed by the concept of ambient stressors. Ambient stressors are defined as environmental factors that are perceptible (although they may go unnoticed), chronically present, negatively valued, non-urgent and intractable, meaning an individual cannot alter these stressors structurally (Campbell, 1983). They might impact behavior and health not only by physical, but also subjective means in that they elicit stress reactions through different, context-dependent cognitive and emotional pathways that are illustrated in an eclectic model from Bell, Greene, Fisher, and Baum (2001). Following this model, environmental stimuli are perceived and appraised in regard to personal adequacy of stimulation. These processes – appraisal more than perception – are influenced by physical properties of the stimuli, as well as personal attributes and situational conditions. Homeostasis is sustained if stimuli are within the desired range of stimulation, which may contribute to positive affect, neighborhood satisfaction and thus, to life satisfaction (Amérigo, 2002; Francescato, 2002). However, individuals appraise environmental factors negatively when they perceive a shift from homeostasis toward disinclination (cf. Klix, 1983). Lazarus and colleagues have extensively described and studied this process as stress appraisal (Lazarus, 1991; Lazarus & Cohen, 1978; Lazarus & Folkman, 1984; Lazarus & Launier, 1978). Negative appraisal may result in heightened arousal, changes in emotional states, in cognitive functions and behavior. Subsequently, a coping strategy (i.e., an intentional behavioral or intrapsychic effort) is chosen to restore homeostasis and accordingly, the stimulus is reappraised. If coping was successful, the same stimulus is less likely to cause negative appraisal and/or the corresponding reactions the next time it is perceived. Otherwise, heightened arousal continues or stress is even intensified due to unsuccessful coping efforts. Prolonged or repeated exposure to stressors can enhance the risk of detrimental after-effects such as mood disturbances, social withdrawal, sleep loss or elevated blood pressure (Adler & Hillhouse, 1996; Cohen, Evans, Stokols, & Krantz, 1986; Dougall & Baum, 2001; Marsland, Bachen, Cohen, & Manuck, 2001). While the eclectic model is capable of explaining inter-individual differences in reaction to an acute environmental stimulus, it needs to be specified for field research on long-term effects of neighborhood burdens in three aspects: the concept of coping, physiological pathways, and the co-occurrence of multiple burdens.

First, coping strategies successful in mitigating stress reactions are likely to be maintained. While this is a well-adaptive mechanism in most cases, one stress-attenuating strategy deserves special interest because it poses a health risk on its own: Consumption of psychotropic substances such as alcohol and nicotine. For example, smoking was shown to increase with elevated levels of ambient stress (Cherek, 1985). Conversely, unsuccessful coping efforts are unlikely to be sustained over a longer period of time and may be displaced by passive mindsets (e.g., prolonged concern or resignation; Homburg & Stolberg, 2004; Ruff, 1990). Moreover, two other intrapsychic assimilation mechanisms occurring on a rather unconscious level are plausible with repeated or prolonged exposure to environmental burdens: Cellular adaptation occurs when neurophysiological sensitivity diminishes, resulting in modified perception (cf. Campbell, 1983). Cognitive habituation may occur because stimulus uncertainty is reduced or due to reduction of cognitive dissonance and results in modified appraisal (Festinger, 1957). In short, negative appraisal of permanent environmental conditions and frequent substance consumption can be regarded as a result of the inability to constructively cope with, adapt to or habituate to environmental burdens. Both phenomena are a health risk factor and thus, of central interest.

The second aspect in Bell et al.'s (2001) model to be explicated refers to the finding that subjective stress responses do not always predict the elevation of physiological responses (Kirschbaum, Kudielka, Gaab, Schommer, & Hellhammer, 1999). Thus, environments with high ambient stressor levels may permanently elicit neural and neuroendocrine responses, regardless of cognitive processes. When this state of ‘allostatic load’ (McEwen, 2000) coincides with other risk factors such as higher age, low social status or low social support (Picket & Pearl, 2001; Wills & Fegan, 2001), the risk of stress-related symptoms enhances (e.g., retarded speed of disease recovery, susceptibility to infectious diseases, hypertension, steroid diabetes, ulcers, etc.; for reviews, see Carlson, 2004; Dougall & Baum, 2001; Kaltsas & Chrousos, 2007; Marsland et al., 2001).

Finally, the model focuses on how singular stressors act. However, neighborhoods may be confronted with multiple ambient stressors that are present at the same time, as they might co-vary in spatial and temporal occurrence when emitted from the same source (e.g., road traffic emits noise, unpleasant odors, and air pollutants at the same time). According to Lepore and Evans (1996), multiple environmental stressors exert independent effects when one stressor does not deplete general coping resources, when it demands a different reservoir of resources (e.g., social vs. material resources), or different strategies (e.g., mental problem solving vs. passive acceptance) than other stressors. Thus, a potentiating effect is more likely when acute stress elicited by one factor reduces capacity to cope with or adapt to concurrent or subsequent stressors.

In the literature on ambient stressors, traffic noise has received more attention than other omnipresent forms of environmental pollution (e.g., unpleasant odor burdens, litter, heat waves, air pollution, noise from other sources such as industry or humans; for reviews see Bullinger, 1998; Cohen et al., 1986; Craik & Zube, 1976; Evans, 2001, 2003; Glass & Singer, 1972; Moser & Robin, 2006; Taylor, Repetti, & Seeman, 1997). While short-term stress reactions to acute ambient stressor exposure and negative appraisal reactions to long-term exposure are well accepted for most of these factors, clear evidence of long-term health effects is lacking. Clark and Stansfeld conclude in their review (2007) that traffic noise impacts subjective quality of life, increases psychological symptoms reporting, and is marginally associated with an enhanced risk of hypertension and coronary heart disease. Conversely, air pollution seems to have a small but significant relation with clinically diagnosable mental health outcomes (see Evans, 2003).

In regard to the effects of multiple stressor exposure, interactive effects of one ambient stressor with another kind of stressor (e.g., stressful life events, work and personal project stress, etc.) cannot be excluded (Evans, 2003; Wallenius, 2004; for reviews, see also Gump & Matthews, 1999; Lepore & Evans, 1996). However, there are few publications on how multiple ambient stressors co-occur. In experimental studies, an interactive effect was found for noise and social crowding, but not for noise and vibration (Ljungberg & Neely, 2007; Martimportugués-Goyenechea & Gómez-Jacinto, 2005). In neighborhood research, physical ambient and social stressors (e.g., loitering, incivility, neighborhood maintenance or structural problems, signs of crime, etc.) are often aggregated into one single stress indicator (Agyemang et al., 2007; Dalgard & Tambs, 1997; Ellaway, Macintyre, & Kearns, 2001; Feldman & Steptoe, 2004; Matheson et al., 2006; Silver, Mulvey, & Swanson, 2002; Weich et al., 2001). According to these studies, neighborhoods with higher stress scores tend to be of lower socioeconomic status than areas with lower stress scores. Moreover, their residents tend to report lower neighborhood satisfaction and poorer physical and mental health, controlling for individual-level socioeconomic status. These studies implicitly assume additive stressor effects, but the relative contributions of single stressors to overall effects and their interplays remain unrevealed (see also Winkel, Saegert, & Evans, 2009).

In addition to the impact of urban environmental stressors on human health, the beneficial effects of urban ecosystems have recently received growing interest (e.g., Ward Thompson, Aspinall, & Bell, 2010). There are two main research positions that argue for evolutionary-based benefits of natural environments, a psychophysiological approach and a cognitive mechanisms approach. In short, the first tradition arose from Ulrich's stress reduction theory (SRT) and focuses on the capacity of natural environments to foster restoration, that is, recovery from environmentally and otherwise induced stress (Ulrich, 1983). According to SRT, natural environments provide restoration by visual characteristics that signal resources relevant to survival and well-being. Due to an inherited tendency of humans to respond to such cues with positive affect, these environments aid return to moderate levels of autonomic arousal (see also Orians & Heerwagen, 1992). The other tradition is based on Kaplan and Kaplan's attention restoration theory (ART, 1989). ART assumes natural environments enable recovery from directed attention. This capacity is explained by specific qualities inherent in natural environments that allow for effortless attention. Kaplan (1995) suggests an integration of these two perspectives. Specifically, as stress reduction might enhance attention capacity, restored attention might contribute to stress reduction, or positive effects of natural environments on both functions could be plausible. Beyond these pathways, urban green spaces may support health in additional, indirect ways (cf. De Vries, 2010). That is, they might stimulate physical activity, which is in turn beneficial to health (see Phillips, Kiernan, & King, 2001, for a review). Moreover, they might enable or facilitate social contacts and thus help gaining social support, which protects against poor health, as discussed in Section 1.1.

Numerous studies have shown greater beneficial effects of natural vs. non-natural environments. Public green spaces in close proximity to home buffer the impacts of stressful life events (Van den Berg, Maas, Verheij, & Groenewegen, 2010; Wells & Evans, 2003). They are related to enhanced neighborhood satisfaction, self-reported physical health and longevity, and to reduced anxiety and depression (Maas, Verheij, Groenewegen, de Vries, & Spreeuwenberg, 2006; Maas et al., 2009; Takano, Nakamura, & Watanabe, 2002). While research has mainly focused on the use of green spaces, the frequency of visiting these areas does not fully explain such effects (Nielsen & Hansen, 2007). Some authors suggest that visual exposure to shared natural space or vegetation in general might explain the health effects of these resources (e.g., Aries, Veitch, & Newsham, 2010; Hur, Nasar, & Chun, 2010; Kaplan, 2001; Kearney, 2006; Kuo & Sullivan, 2001). Moreover, small patches of green and vegetation may stimulate the use of outdoor spaces and social activities (Sullivan, Kuo, & Depooter, 2004).

In light of the beneficial health effects of natural elements, urban neighborhoods with few health-relevant resources offer fewer opportunities for recreation. Thus, inadequate availability of urban vegetation and public green spaces can be considered environmental burdens and, therefore, potential health risks. These kinds of burdens might often co-occur with the health risks arising from ambient stressors. For example, as the number or size of urban green spaces increase in neighborhoods, physical environmental quality improves by function of air pollutant absorption, noise reduction and microclimate regulation (Bolund & Hunhammar, 1999; Kowarik et al., 2011; Langner, Kull, & Endlicher, 2011). Moreover, research findings suggest that such resources may counterbalance the psychological effects of ambient stressors in urban neighborhoods (see Gee & Payne-Sturges, 2004, for a review; Leslie & Cerin, 2008). For example, perceived availability of nearby green areas was found to decrease annoyance reactions to traffic noise (Gidlöf-Gunnarsson & Öhrström, 2007). Therefore, we argue for an integrative framework (see Fig. 1) that takes into consideration both ambient stressors and lack of natural resources, as well as their interplay, in order to enhance ecological validity of research on neighborhood health effects.

To our knowledge, this is the first study to assess and compare the relative relations and interplay of multiple ambient stressors and lack of natural resources in regard to self-rated neighborhood-related health outcomes. Using Geographical Information Systems (GIS), we analyzed the spatial variability of two ambient stressors (traffic noise, air pollution) and one ecological resource (provision with public green space) in order to identify inner-city neighborhood street blocks in Berlin with high and low burden levels. These factors were selected because, as the above-discussed literature suggests, they are the factors with most probable singular health effects. Afterward, a household questionnaire survey was conducted among residents of these sites. The perceived levels of three other ubiquitous and locally relevant environmental burdens (van der Meer et al., 2011) were assessed as additional predictors for which no suitable GIS-data exist: Litter and dirt in the public space, behavior-related noise and lack of urban vegetation. We hypothesize that objective variations of environmental burdens are reflected in subjective environmental evaluations and in neighborhood-related health indicators. Moreover, we consider perceived levels of additional non-varied environmental burdens for new insights regarding the multiple-burden framework. Predictions of either independent or interactive effects of multiple co-occurring burdens, as Lepore and Evans (1996) suggest, are impossible due to a lack of literature on burden-specific coping strategies. Thus, we investigate the relative strength of each of the factors, the potential interactions among them, and their covariation in an exploratory way.