摘要：Objectives. The indoor environment has not been fully incorporated into the environmental justice dialogue. To inform strategies to reduce disparities, we developed a framework to identify the individual and place-based drivers of indoor environment quality. Methods. We reviewed empirical evidence of socioeconomic disparities in indoor exposures and key determinants of these exposures for air pollutants, lead, allergens, and semivolatile organic compounds. We also used an indoor air quality model applied to multifamily housing to illustrate how nitrogen dioxide (NO2) and fine particulate matter (PM2.5) vary as a function of factors known to be influenced by socioeconomic status. Results. Indoor concentrations of multiple pollutants are elevated in low-socioeconomic status households. Differences in these exposures are driven by the combined influences of indoor sources, outdoor sources, physical structures, and residential activity patterns. Simulation models confirmed indoor sources’ importance in determining indoor NO2 and PM2.5 exposures and showed the influence of household-specific determinants. Conclusions. Both theoretical models and empirical evidence emphasized that disparities in indoor environmental exposure can be significant. Understanding key determinants of multiple indoor exposures can aid in developing policies to reduce these disparities. The persistence of racial/ethnic and socioeconomic health disparities in the United States remains a significant public health problem. One focus of the environmental justice (EJ) movement has been the contribution of the physical and social environments in shaping adverse health outcomes among poor communities of color. The emphasis of EJ has historically been on outdoor pollution sources such as industry or traffic, in part because of EJ's origins in addressing historical and continued institutional racism through the siting of industrial facilities, illegal and regulated dumping, and land use planning in communities lacking the political capital that would promote a more equitable distribution of risk. 1 – 5 Although these outdoor sources can clearly influence health disparities given uneven distributions across communities, 6 , 7 an underappreciated EJ issue relates to disparities in indoor residential environmental quality. The direct effect of dilapidated housing and poor sanitation on health has been documented since the 19th century, 8 – 12 because good public policy did not develop in step with rapid urbanization and population growth. Over the past century, understanding of the connections between housing and health has expanded beyond sanitation, infectious disease, and safety to include a broad list of agents associated with morbidity and mortality, such as radon; asbestos; lead; insect and pet allergens; chemicals in wall coatings, furnishings, and consumer products; penetrating outdoor toxics; pesticides; and secondhand smoke, combustion byproducts, and fungi. 13 – 15 Although the linkage between housing and health has been firmly established, it has occurred largely outside of the EJ movement. As researchers attempt to inform activities which may eliminate known and emerging disparities in environmental risks, addressing indoor environmental exposures will be critical, and doing so will require an understanding of the root causes of these uneven distributions. Addressing indoor exposures is challenging because they include contributions from both indoor and outdoor sources and because they may be influenced by variables that are socioeconomically patterned (e.g., dwelling size) and by institutional factors that define housing quality and neighborhood attributes (e.g., ambient pollution). However, residential indoor exposures are shaped by specific physical and chemical mechanisms that can be described and modeled. Physical models describing emissions, air exchange, dynamic partitioning, deposition, and other critical processes can aid in the evaluation of risk-reduction strategies. These models can also help identify underlying determinants of exposures, including root causes related to socioeconomic and demographic characteristics that add to the overall burden of health disparities. For example, indoor concentrations of airborne pollutants may be driven by the design or condition of the home's physical structure; resident behaviors; product use profiles; characteristics of household furnishings; presence, condition, and use of mechanical ventilation; air infiltration pathways (especially in multifamily settings); and outdoor pollutant concentrations. We describe the empirical evidence of socioeconomic disparities in indoor environmental exposures and exposure-related factors and discuss how a framework that identifies the dominant individual, place-based, and institutional drivers of these observed exposure disparities can inform interventions and risk reduction. Although exposure disparities may be observed in multiple settings, we focus our discussion and case study on urban, multifamily households to highlight some general principles and the unique challenges in these settings.
