A Framework for Examining Social Stress and Susceptibility to Air Pollution in Respiratory Health

Abstract

ObjectiveThere is growing interest in disentangling the health effects of spatially clustered social and physical environmental exposures and in exploring potential synergies among them, with particular attention directed to the combined effects of psychosocial stress and air pollution. Both exposures may be elevated in lower-income urban communities, and it has been hypothesized that stress, which can influence immune function and susceptibility, may potentiate the effects of air pollution in respiratory disease onset and exacerbation. In this paper, we attempt to synthesize the relevant research from social and environmental epidemiology, toxicology, immunology, and exposure assessment to provide a useful framework for environmental health researchers aiming to investigate the health effects of environmental pollution in combination with social or psychological factors.Data synthesisWe review the existing epidemiologic and toxicologic evidence on synergistic effects of stress and pollution, and then describe the physiologic effects of stress and key issues related to measuring and evaluating stress as it relates to physical environmental exposures and susceptibility. Finally, we identify some of the major methodologic challenges ahead as we work toward disentangling the health effects of clustered social and physical exposures and accurately describing the interplay among these exposures.ConclusionsThere is still tremendous work to be done toward understanding the combined and potentially synergistic health effects of stress and pollution. As this research proceeds, we recommend careful attention to the relative temporalities of stress and pollution exposures, to nonlinearities in their independent and combined effects, to physiologic pathways not elucidated by epidemiologic methods, and to the relative spatial distributions of social and physical exposures at multiple geographic scales.

An Agenda to Advance Integrative Resilience Research and Practice: Key Themes From a Resilience Roundtable

“…For example, repeat activation of the sympathetic nervous system in response to acute stressors can interfere with growth during child development. An extreme example of this phenomenon is psychosocial short stature (a version of failure to thrive), where the production of growth hormone is affected due to repeated release of stress hormones (Clougherty & Kubzansky, 2009). …”

Susceptibility Factors Relevant for the Association Between Long-Term Air Pollution Exposure and Incident Asthma

“…Some specific population groups seem to be more sensitive to air pollution effect such as children, elderly people, overweight or obese individuals [4], subjects with chronic respiratory disease such as asthma [5] or chronic obstructive pulmonary disease [6]. Sex differences have also been found [7]. Regarding air pollution, there is no consensus on specific susceptibility factors that would be common across all health outcomes.…”

Perspectives in Household Air Pollution Research: Who Will Benefit from Interventions?

“…Several investigators have hypothesized that those individuals who are more susceptible to the adverse effects of air pollution exposure may also be the groups that benefit most from efforts to reduce air pollution levels (e.g., traffic reduction plans, industrial facility closings, indoor air filter interventions) [47,48], yet this question has largely been ignored in the cookstove field. Valid assessments of the true exposureresponse relationships among various subpopulations are necessary to inform a more accurate estimate of the global burden of disease attributed to cookstove smoke, an identified research gap needed to convince governments and policy makers to enact interventions [49].…”

“…Challenges also arise when predicting health benefits for various subgroups of the population if the risk factor that defines the responder subpopulation has a nonlinear or threshold effect on the health endpoint of interest [48]. For example, improvements were not observed in symptoms following an allergen-reducing indoor air quality intervention in a public housing complex among asthmatic children reporting exposure to a psychosocial risk factor (e.g., fear of violence) [55].…”

“…Counter to initial hypotheses, those with factors typically thought to confer increased susceptibility to the adverse effects of air pollution exposures (e.g., psychosocial factors and obesity) did not experience greater benefits following reductions in air pollution exposures. These types of scenarios suggest that threshold or saturation effects occurring among those highly exposed to a secondary risk factor may overshadow or even negate any potential improvement resulting from a reduction in air pollution [48]. This phenomenon may be a particularly important consideration to discern when estimating benefits from cookstove interventions since the target populations are typically affected by several co-occurring risk factors (e.g., low socioeconomic status, poor nutrition, exposures to pesticides), many of which are increasing rapidly in some developing countries (e.g., obesity, diabetes).…”