Introduction

For the first time in human history, more people reside in towns and cities than in rural settings. In the United States, 82% of the population is located in urban areas.[1] Urban living can provide benefits such as access to health, educational and social services, cultural resources, and a lively community life. Yet some urban locations are associated with seriously compromised life opportunities. It has been repeatedly shown that physical and social environments are important determinants of health. Therefore, the subject of urban health is important for professionals concerned with the well-being of individuals and populations. Urban health encompasses a broad range of issues from housing and diet quality, substance abuse, and violent crime to mental health and social cohesiveness. Because these factors are so intimately related, it is not possible to examine any single factor in isolation. Nevertheless, the scope of this essay will be limited mainly to urban physical environments and their impact on health.

We will begin with a historical overview of urbanism and its attendant health consequences. We will highlight some of the approaches employed in response to past urban health issues. Next, we will examine the relationships between contemporary urban physical environments and health behaviors and outcomes. Finally, we will discuss responses to these health issues, focusing on the roles of public health clinicians and other healthcare providers.

Historical Overview

The founding of the first cities in the Mesopotamian valley 7000 years ago marked a watershed moment in the development of human civilization. The agricultural surpluses from those fertile lands spurred a series of changes that profoundly affected the way people related to the natural environment and to each other. Instead of each household growing food for its own sustenance, individuals entered into specialized occupations and neighbors began to live in closer proximity to each other. Societal leaders organized and administered community resources, and for the first time, groups of people systematically planned and executed large-scale public works.[2]

These monuments and systems marked humanity's increasing mastery over the environment. People began to enjoy a new level of security from risks characteristic of a rural and agrarian way of life -- but with some tradeoffs. Although floods, famine, and wild beasts were of less concern, a new set of health risks specific to the urban milieu emerged in their place. Further, the division of labor and accumulation of wealth by a subset of the population set the stage for increased social stratification,[2] which we now know has its own independent effects on health.[3,4,5,6]

The industrial revolution provides a striking example of how differential access to resources and decision-making power led to an unequal distribution of risks to health and safety. During the early 19th century, millions of families relocated to urban areas, attracted by the availability of work and opportunities for social advancement. Because the nascent urban infrastructure was unprepared to deal with this influx, overcrowding and inadequate sanitation took their toll in the form of typhoid fever, cholera, and other infectious diseases that wiped out large segments of the population, particularly among the working classes.[7]

The landmark Report on the Sanitary Condition of the Labouring Population of Great Britain developed by Edwin Chadwick[8] in the 1830s brought attention to these issues and outlined the means for their abatement. Although change was slow in coming, the report ultimately led to the passage of legislation that laid the foundations of modern public health. The new law established a central Board of Health and allocated governmental resources to the provision of adequate sewer and water systems.[9] Similar measures were later implemented in the United States, although these were frequently delayed for years by the political interference of industrialists.[10]

By the late 1800s and early 1900s, rapid industrialization had led to such severe air pollution that daytime visibility was often reduced to a few yards.[11] Recognition of the hazards of industrial pollution led to the enactment of zoning ordinances in many US cities. For the first time, areas for commercial use, private dwellings, and industry were physically separated. Despite the salubrious intent of these policies, their practical application had some unintended consequences. Longer distances between places of residence and work meant that many more people were using motorized transportation. The few who could afford to make their daily commutes by automobile relocated to outlying areas, whereas people who relied on public transportation remained in the decaying central urban zones. In addition, many municipalities created zoning policies such as minimum residential lot and dwelling sizes that effectively excluded members of racial and economic underclasses.[12,13]

In the ensuing decades, mass production of affordable automobiles and the creation of the federally subsidized interstate highway system in the 1950s reinforced the trend towards increased car ownership. Auto ownership grew from 59% of all households in 1950 to 82% in 1970.[14]

At this point, the stage was set for the suburban explosion of the 1970s and 1980s. Areas around the outer perimeter of cities were developed into low-density settlements with strict separations of land uses. These neighborhoods necessitated the construction of more roads. In addition, lower-density settlements engender increased per capita costs for municipal services and infrastructure, meaning higher taxes for residents. Eventually, the inconvenience of long commutes, traffic congestion, air pollution, high tax rates, and rising gas prices began to outweigh the attractions of the suburbs. In recent years, demand for urban housing has been greater than that for suburban real estate.[15,16]

Modern Cities and Health

Most of the US population now resides in urban areas.[1] Contemporary urban centers bear little resemblance to the fledgling cities of the industrial revolution. Urban dwellers today enjoy greater educational and cultural opportunities than nonurbanites. Moreover, social and healthcare services are far more accessible to people living in or near cities. However, green space is rare in urban neighborhoods. Physical activity is not an integral part of work or transportation for many urbanites and their recreational activities are mostly sedentary. As in Chadwick's era, a disproportionate burden of environmental effects on health continue to be borne by racial and economic underclasses. Studies have shown associations between residing in areas with high levels of racial segregation, unemployment, or poverty and having a higher body mass index,[17] a greater incidence of coronary artery disease,[18] and higher overall mortality,[19,20] even after adjustment for individual behaviors and socioeconomic status.

Characteristics of the manmade, or "built," environment appear to be correlated with levels of physical activity. Neighborhoods with high street connectivity -- that is, streets organized in a grid pattern without obstacles to pedestrian travel -- are associated with more frequent walking.[21] Walking is also more frequent in areas where the distance between destinations is small, where sidewalks are present, and where parks and open space are accessible.[22] In addition, perceptions of neighborhood safety have been correlated with physical activity, particularly among older adults.[23] Conversely, higher levels of urban sprawl, characterized by low-density development, strict separation of land uses, and poor street connectivity, are associated with less time spent walking and higher body mass index.[24]

The relationship between the physical environment and physical activity behaviors is complex and incompletely understood. Most of the available data are from cross-sectional studies with measurements taken at 1 or 2 points in time. As a result, firm conclusions about the impact of the environment on behavior cannot be made. Nevertheless, the promising findings to date have generated immense excitement and unique collaborations among individuals and groups interested in health promotion, urban planning, active transportation, sustainable living, and environmental conservation.

One such enterprise is the Smart Growth Network, which is a collaboration between the US Environmental Protection Agency and governmental and nonprofit organizations. The Smart Growth movement aims to promote development that is transit- and pedestrian-oriented, has a greater mix of land uses, and preserves open space and other environmental amenities.[25] Its goals align closely with the Federal Transit Administration's Livable and Sustainable Communities Initiative, which aims to increase the availability of high-quality public transportation options, reduce transportation costs, and decrease emissions.[26] The federal Safe Routes to School program provides funds for the construction of pedestrian and cyclist-friendly infrastructure as well as educational and encouragement programs that promote walking and cycling to school by primary and middle school students.[27] In addition, the Robert Wood Johnson Foundation's Active Living by Design initiative sponsors research to delineate the relationship between environmental factors and policies and physical activity.[28]

The Health Impact Assessment (HIA) tool has the potential to bring a population health perspective to urban planning and development decisions. HIAs are similar in concept to Environmental Impact Assessments (EIA), which assess the possible environmental consequences of a proposed policy or project. Completion of an EIA is required by the federal government for proposed actions that could significantly affect the quality of the human environment.[29] Assessment of impact on human health has not traditionally been a part of the EIA process, but in some cases EIAs have included estimations of the carcinogenic or teratogenic potential of exposure to a specific toxin.[30] In contrast, HIAs focus on the broader determinants of health, including physical and social environments. These assessments will facilitate communication among health professionals, urban planners, transportation officials, and developers.

Addressing Physical Inactivity

The disappearance of physical activity from daily life, accompanied by a modern diet high in calorically-dense processed foods, has resulted in a rising prevalence of overweight and obesity and increasing rates of high blood pressure, diabetes, and cardiovascular disease.[21] Physical inactivity is now one of the most important modifiable causes of chronic disease in the United States.[31]

According to the 2009 Behavioral Risk Factor Surveillance System, only 50% of adults achieve the minimum amount of physical activity recommended by the Centers for Disease Control and Prevention (Table), and nearly a quarter of adults report that they are completely sedentary.[32] Even more alarmingly, only 18% of high school children reported meeting minimum activity recommendations in 2009.[33]

Table. Centers for Disease Control and Prevention Physical Activity Recommendations[34]

Children
Aerobic Activity Vigorous-intensity aerobic activity at least 3 days per week
Muscle Strengthening Gymnastics or push-ups, at least 3 days per week
Bone Strengthening Jumping rope or running, at least 3 days per week
Total 420 minutes per week (60 minutes per day)
 
Adults
Aerobic Activity 150 minutes per week of moderate or 75 minutes per week of vigorous activity
Muscle Strengthening 2 or more days a week, working all major muscle groups (legs, hips, back, abdomen, chest, shoulders, and arms)

US Department of Health and Human Services. Centers for Disease Control and Prevention: Division of Nutrition, Physical Activity, and Obesity. Physical Activity Guidelines for Americans. Available at: http://www.health.gov/PAGuidelines/

Given the enormous potential to improve longevity and quality of life, reduce the incidence of chronic diseases, and lower healthcare costs,[35] addressing physical inactivity must be an essential component of any serious effort to improve the health of the US population. Undoubtedly, achieving positive behavior change can be a time-intensive and frustrating endeavor. Chances of success are much improved when the issue is addressed at multiple levels of influence, including socioeconomic factors, environmental and policy changes, community or workplace-based programs, and clinical interventions.

Behavioral counseling. Individual behavioral change counseling is underused for a number of reasons, including inadequate training of healthcare providers, lack of reimbursement, and an absence of support systems in the clinical setting. Furthermore, counseling can be time-consuming and requires multiple provider-patient interactions. Even when it is applied properly, the impact achieved by any single provider is modest, with only a small percentage of patients who receive a counseling intervention making clinically significant changes. Nevertheless, these seemingly insignificant effects add up to substantial benefits to the health of the population when the intervention is systematically applied.[36]

The US Preventive Services Task Force (USPSTF) last reviewed the evidence for counseling to improve physical activity in 2002. They concluded that evidence was insufficient to recommend for or against routine counseling for all patients.[37] The USPSTF does recommend routinely measuring body mass index for all adults and providing intensive behavioral counseling for obese patients.[38] In addition, the American Heart Association recommends that all healthcare professionals advise patients to accumulate the recommended amounts of moderate-intensity physical activity. They further recommend that the advice be personalized to each patient's interests, needs, schedule, and environment.[39]

The 5 As construct for behavioral change counseling, adapted from clinical interventions for tobacco cessation, has been endorsed by the USPSTF for behavioral counseling in primary care.[36] A brief description of each component of the 5 As follows, along with suggestions for their implementation.[40]

1. Ask/Assess: Inquire about health behaviors

  • Ask about the patient's physical activity habits, including specific details about intensity, duration, frequency, location, and type of activity.

  • This step may include assessment of knowledge and beliefs about the importance of physical activity, degree of motivation to change, and preferences about types of physical activity.

  • Support staff may perform this step prior to the clinician visit.

2. Advise: Give clear, specific, and personalized advice, including information about personal health harms and benefits.

  • Clearly recommend that the patient participate in regular physical activity.

  • Link the advice to the patient's health concerns, past experiences, family history, and socioeconomic status.

  • Use teachable moments to relate the patient's symptoms, concerns, or laboratory test results to his or her behavior.

  • Deliver the advice on a level that is appropriate to the patient's health literacy.

3. Agree: Collaboratively select physical activity goals and tasks based on the patient's interest and motivation.

  • Make efforts to ensure that the patient actively participates in the goal-setting process.

  • Create an individualized action plan detailing short- and long-term strategies and goals. Specify the type(s) of physical activity, frequency, and duration. Print a copy of the action plan for the patient to take home.

  • Consider referral to another provider such as a health educator if lower-intensity counseling fails to achieve the desired results.

4. Assist: Using self-help resources and/or counseling, help the patient achieve his or her goals by acquiring skills, confidence, and social and environmental supports for behavior change.

  • Help the patient anticipate potential barriers such as inclement weather, lack of time, safety concerns, and childcare obligations.

  • Strategize together to create a list of possible solutions and ways to prevent relapse to less activity.

  • Provide information about available community resources such as community parks and pools, walking clubs, or shopping malls where individuals can exercise indoors.

  • Provide guidance in obtaining social support from friends and family.

  • Encourage self-monitoring and self-reward. Provide a log book for the patient to record physical activity. Agree on a healthy reward the patient will enjoy upon reaching his or her short-term goals.

5. Arrange: Schedule follow-up contacts (in person or by telephone) to provide ongoing support and to adjust the treatment plan as needed.

  • Schedule a follow-up appointment. It is best to schedule the initial follow-up within a short time frame (eg, 1 month).

  • Evaluate and adjust the behavior change plan, usually by briefly repeating the first 4 As, taking into account the patient's intervening experiences.

As noted above, the full benefit of behavioral counseling is realized only when it is applied systematically to large segments of the population at risk. Counseling interventions are delivered more consistently and effectively when they are supported by tailored office systems for preventive services. Support systems identify which patients need the service and remind the clinician of this need during a visit. Support systems may also link patients with community resources such as counseling and support services and may cue appropriate follow-up and referral. More advanced systems incorporate performance feedback to providers.[36,40]

Environmental and community-based approaches. The Task Force on Community Preventive Services recommends several interventions that complement clinical services by acting on levels of influence that have the potential to benefit all members of the community or population. The 4 recommended interventions that relate to urban environments are summarized below, along with suggested action items for clinicians and public health professionals.[41]

1. Point-of-decision prompts to encourage use of stairs. Signs placed near stairwells, elevators, and escalators reminding people about the health benefits of physical activity and encouraging individuals to take the stairs are an effective means of promoting activity. This intervention can be applied in almost any setting and can be a means through which clinician leaders set an example for their patients and the community.

Action items:

  • Institute point-of-decision prompts at your place of work and encourage others to do the same.

  • It is important that stairwells be visible and accessible. You may need to work with maintenance personnel to ensure the stairways remain unlocked during business hours.

2. Creation of or enhanced access to places for physical activity combined with informational outreach activities.Examples of this type of intervention include the construction of walking or cycling trails, building new playgrounds and parks, or opening existing facilities to the public.

Action items:

  • If you are an employer, consider offering employees subsidized membership to a nearby fitness center. This can be part of a more comprehensive workplace wellness program.

  • If you are a member of any neighborhood associations, advocacy groups, or service organizations, talk with them about the benefits of increasing access to places for physical activity in your area. They can be powerful advocates for the construction of parks, walking or cycling trails, and other amenities.

  • Work with local leaders to open public school facilities for community use after hours.

3. Street-scale urban design and land use policies. The goal of this intervention is to change the physical environment of small geographic areas (eg, a few blocks) in ways that support physical activity. Examples include zoning policies that allow for a mixture of land uses in close proximity to each other or encouraging development projects in the planning stages to incorporate high street connectivity and ample sidewalk space. Another means to support physical activity is to enhance the aesthetic and safety aspects of the environment by installing lighting, planting trees, or erecting public art.

Action items:

  • Talk with individuals who make decisions about zoning, planning, and development, such as city council members and county commissioners.

  • Attend public hearings at which proposed zoning changes or development projects are discussed and share your knowledge about the health effects of these decisions.

  • Invite elected officials on a walking tour to experience transportation infrastructure from the pedestrian perspective.

  • Install bicycle racks in a visible location outside your office.

4. Community-scale urban design and land use policies.This intervention is similar to the previous one but is applied on a larger scale. It aims to change the physical environment of urban areas (eg, several miles or more) in ways that support physical activity.

Action items:

  • Develop relationships with individuals who make transportation policy and urban planning decisions. These may include officials from the Department of Transportation, the Department of Public Works, or the Metropolitan Planning Organization.

  • Join the local or regional citizen advisory committee on transportation issues. Participating in this organization provides the opportunity to network with staff and help guide the planning process.

  • Find out if your city or state has a "complete streets" policy in place. Complete streets policies ensure that transportation agencies consider the needs of all users, including drivers, transit users, pedestrians, and bicyclists.[42] Schedule meetings with your elected officials to discuss the importance of having a complete streets policy that is consistently implemented.

Conclusion

Most of the US population now resides in urban areas, and the importance of the urban physical environment on human health is being increasingly recognized. Decades of urban development that encouraged automobile dependence has led to alarming levels of physical inactivity and contributed to an epidemic of obesity and rising rates of chronic disease. To effectively protect the health of the public, interventions must be targeted at all levels of influence. Personalized behavioral change counseling can have a significant population health impact if it is systematically applied. Nevertheless, clinical interventions must be supported by environmental and community-based approaches if healthy behaviors are to become the norm. Finally, if we as a nation are to make an impact on our severe and persistent health disparities, we must first find the means to alleviate the social and economic inequities that pervade our society.

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