The loss of commercial and industrial employers in cities has increased the physical distance between inner city residents and available jobs [17
]. At one time, US metropolitan areas had strong downtown commercial districts surrounded by dense residential areas with industrial areas also close to worker housing. But decades of de-industrialization and suburbanization have resulted in a large transfer of jobs away from inner city neighborhoods towards suburban employment centers [18
]. The result is that inner city communities are no longer close to employment opportunities, a phenomenon that economists characterize as "spatial mismatch" [20
]. One consequence of this mismatch is that fewer inner city residents can walk or take local public transportation to work. They have long commutes, particularly the significant numbers that do not own cars, which ultimately could leave them little free time to be physically active or to socialize with their neighbors. To a great extent, this mismatch is not the result of zoning or government land use decisions that separate land uses in suburban areas. Rather it is the result of disinvestment and job loss in inner cities that has also contributed to the impoverishment of inner city governments and residents. Many of these economic changes have also resulted in a "loss of place" in that neighborhoods take on a tooth-gapped appearance with empty storefronts, abandoned buildings and vacant lots [21
], likely making them less attractive for walking or for children playing outside.
In suburbs, solutions to the problem of special mismatch might include zoning reform and design guideline changes to allow mixed use development and encourage the development of office and commercial properties close to residential areas [22
]. Inner city remedies, on the other hand, may require a different set of policy solutions, such as renewed investment in inner city neighborhoods, greater training and educational opportunities to increase skill match with existing jobs, and aggressive redevelopment of brownfields (contaminated urban parcels) for commercial/industrial development. Case studies and evaluation research of inner city neighborhood and brownfield redevelopment would help answer the question of whether and how resident physical activity is impacted by economic and neighborhood revitalization, and would garner lessons from neighborhood development models that are conducive to walking and other forms of physical exercise.
Of the non-residential land uses remaining in inner cities, many may well discourage walking and physical activity. Numerous studies have documented that hazardous waste facilities and factories that are required to report their toxic releases to the federal government (i.e., larger facilities) are disproportionately located in poor neighborhoods and communities of color [23
]. An early study in Houston showed that solid waste dumps were more likely to be found in Black neighborhoods [24
]. Toxic facilities in Los Angeles are more likely to be sited in minority and working class communities than in more affluent, white neighborhoods of the city [25
]. A recent study of hazardous and solid waste sites, power plants, and polluting industrial facilities in Massachusetts cities and towns, found that low income communities were cumulatively exposed to environmentally hazardous facilities and sites at four times the rate of high income communities. For high minority communities, the rate was twenty times that of low minority communities [26
]. Comparative studies of inner-city neighborhoods by health factors, such as exercise and prevalence of overweight, and by environmental factors, such as density and type, size, and proximity of polluting facility, would help identify the impact of local polluting facilities on residents' physical activity and overweight.
Coinciding with the health risk of physical inactivity in inner cities is the reality of food insecurity. Many older inner-city neighborhoods no longer have a local supply of fresh, healthful food and they often lack transportation access to more remote supermarkets [27
]. Supermarkets are less likely to locate in inner cities and small stores are more likely to sell low quality, non-fresh food and have higher prices, a situation that would contribute to poorer nutrition and lower health status [28
]. The separation of residential areas from commercial services and goods, such as large supermarkets in inner cities, is not the result of intentional zoning policy as in suburbs; rather it is a consequence of social and economic trends, including business flight, that have impoverished older urban neighborhoods. Studies of diet and nutrition among inner city residents need to include research on the prevalence of, proximity to, and transportation access to large supermarkets, as well as comparisons of price and food quality between urban and suburban food markets.
Decades of racial change, segregation, economic disinvestment and discriminatory lending and insurance practices have resulted in a severe reduction of the housing stock in many urban communities, often accompanied by new construction in distant areas [29
]. The social effect of abandonment has been termed "the broken window syndrome": Neighborhoods with broken windows and dilapidated housing encourage crime, pose safety hazards, isolate residents and reduce trust in the ability of the neighborhood to meet its challenges [30
]. One study has linked these factors of neighborhood quality to the risk of acquiring sexually transmitted diseases [31
]. Another consequence of this constellation of risks from a moldering environment would likely be reduced walking, physical activity and recreation in public.
Comparative studies of building conditions, rates of children's play out-of-doors and resident walking could reveal a relationship between residential conditions and physical activity. Poor built environment conditions beg the research question: What is the relationship between building condition, building tenancy, building abandonment and rates of physical activity and obesity?
Even when abandoned buildings are demolished, the resulting vacant land poses problems to the environment [32
]. If untended, these lots usually become overgrown with weeds and covered with litter, an invitation for illegal dumping (including demolition and construction debris, hazardous chemicals and medical wastes), and foster criminal activity. Does vacancy contribute to less walking, playing, and other physical activity in the affected neighborhood? This question, like its companion regarding abandoned housing, has yet to be examined.
If low density is a factor implicated in physical inactivity as some have posited it is important for policy implications to distinguish between lower density neighborhoods caused by abandonment and those resulting from zoning and land use decisions. While the latter is the intentional result of government decision-making, the former is a consequence of a more complex mixture of forces that include public and private sector lending and insurance practices as well as social relations among races in the United States. Solutions, which have centered around increased investment, elimination of discriminatory lending practices and the creation of new, beneficial land uses in inner city communities, such as side lot disposition programs, community gardens, and housing rehabilitation [33
], ought to be evaluated for their potential impact on multiple forms of physical activity, such as more time spent outdoors in walking, gardening, biking, and so on.