摘要：Objectives. We assessed the spatial distribution of subsidized housing units provided through 2 federally supported, low-income housing programs in Orange County, California, in relation to neighborhood walkability, transit access, and traffic exposure. Methods. We used data from multiple sources to examine land-use and health-related built environment factors near housing subsidized through the Housing Choice Voucher Program and the Low Income Housing Tax Credit (LIHTC) program, and to determine these patterns’ associations with traffic exposure. Results. Subsidized projects or units in walkable, poorer neighborhoods were associated with lower traffic exposure; higher traffic exposure was associated with more transit service, a Hispanic majority, and mixed-use areas. Voucher units are more likely than LIHTC projects to be located in high-traffic areas. Conclusions. Housing program design may affect the location of subsidized units, resulting in differential traffic exposure for households by program type. Further research is needed to better understand the relationships among subsidized housing locations, characteristics of the built environment, and health concerns such as traffic exposure, as well as which populations are most affected by these relationships. Smart growth development strategies, which promote high-density, walkable neighborhoods with mixed land-use patterns, high accessibility to public transportation, and convenient local amenities, could encourage walking, cycling, and more active lifestyles and may be associated with potential health benefits such as a lower body mass index. 1–4 Such compact communities provide local amenities close to residences and can be associated with reduced vehicle travel and associated air pollution. 1,5 However, smart growth strategies also could exacerbate exposure to localized air pollution 6–9 because vehicle-related air pollutants, which are associated with health impacts such as heightened respiratory ailments, reduced lung function, and increased mortality, tend to be highly localized during the day in areas approximately 200 to 300 meters downwind of major roadways. 10,11 The health implications of smart growth for disadvantaged groups remain unclear. Although many existing low-income urban neighborhoods are highly walkable, their built environments are less consistently associated with positive health outcomes and lower body mass index. 12 These suboptimal outcomes may be attributable to other neighborhood characteristics, such as higher levels of deprivation, crime, and safety concerns and fewer clean streets with trees, which may inhibit physical activity 13,14 ; more traffic; and exposure to elevated, near-roadway concentrations of vehicle-related pollution. 15,16 Furthermore, smart growth developments that enhance local built environment amenities may increase market demand for nearby housing and decrease the availability of affordable housing. 3 Although previous research examined the impact of overcrowding and poor housing conditions on the health of low-income residents of public housing, 17,18 few studies have examined the extent to which publicly subsidized housing for low-income residents is distributed in relation to health-related built environment factors such as neighborhood walkability, transit access, and traffic exposure. Furthermore, the spatial distribution of affordable units and their proximity to these amenities and hazards could vary systematically by whether the requirements and regulations of affordable housing programs seek to incentivize housing developers to provide low-rent units in new residential buildings or to disperse residents by providing them vouchers to obtain subsidized housing in the wider rental market. We conducted the first comparative analysis of the spatial implications of 2 programs that provide housing units for low-income residents of Orange County in Southern California. Although historically a traditional suburban community, Orange County is rapidly becoming ethnically and socioeconomically diverse, with increasing income inequality. 19 The county does not have traditional public housing, which concentrates low-income residents in projects owned and managed by public housing authorities, but rather depends largely on 2 housing programs for low-income residents, which could result in different spatial distributions of units depending on programmatic approach and local conditions. The Low Income Housing Tax Credit (LIHTC) program is a supply-side program that uses tax credits to raise capital for affordable housing developments. LIHTC development proposals receive points in a competitive process for access to local amenities. Thus, they may be more sensitive to site feasibility considerations and may tend to be located in transportation corridors with lower property values and higher traffic because, in California, the LIHTC program considers access to public transportation in the evaluation of applications. 20,21 The Housing Choice Voucher Program is not place based and instead promotes poverty deconcentration and dispersal by allowing participants to locate a housing unit in the private rental market; the unit must be affordable within program guidelines (according to fair market rent as established by the US Department of Housing and Urban Development) and must pass a housing authority inspection. Furthermore, the landlord must be willing to participate in the program. Previous research identified some health, accessibility, and employment implications of relocating poor residents to nonpoor areas, 22–24 but we know very little about the built environment of neighborhoods chosen by voucher holders. Because many voucher households that move relocate to other poor communities, 25,26 we suspect that their new neighborhoods may be older, dense, and walkable and that they differ spatially from areas prioritized by developers leveraging capital through the LIHTC program.
