We Don't Know Nearly As Much About the Link Between Public Health and Urban Planning As We Think We Do
In the mid-1800s, how we lived had a lot to do with how we caught disease. That's when we first discovered the connection between overcrowded, unsanitary housing and the spread of cholera, tuberculosis, and yellow fever. Back then, the fields of public health and urban planning were practically one and the same.
The two have long since moved in different directions. But there's growing concern that the communities we've built – full of highways, where few people walk, where whole neighborhoods lack food access – may be pushing us towards obesity, heart disease, and asthma. By this thinking, good architecture and urban planning could encourage us to walk more. It could mitigate pollution. It could illuminate the targeted need for amenities like parks and bike lanes in neighborhoods with the worst health outcomes.
An ambitious new decade-long project from the MIT Center for Advanced Urbanism and the American Institute of Architects is built on this premise. As Robert Ivy, the CEO of the AIA, wrote in an introduction to a thick new report on "the state of health + urbanism" from MIT:
When Americans think of health, we instinctively see in our mind’s eye the medical profession and the hospitals and clinics in which they treat illness. We usually do not think of architects and other design professionals. But what if we invited designers to help us reinvent aspects of preventive medicine? What if we adopted design strategies that lead to less sedentary lifestyles?
This is one of the most compelling challenges facing planners and architects in the 21st century. But the MIT report knocks down many of the assumptions that have become entrenched in how we think about health and cities: namely, that walkable cities are healthier than auto-oriented suburbs, that cars are a primary cause of our expanding waistlines, that too much fast food and too little fresh fruit are to blame for inner-city obesity.
In fact, MIT points out that American life expectancy has increased alongside motorization since 1950. Many inner cities actually have higher obesity rates than suburbs. Inner-ring suburbs have some of the best health outcomes. There's no evidence to suggest that sprawl causes obesity, although there is some research arguing that people who already are obese opt to live in sprawling places.
Evidence of direct causation is scant throughout this entire emerging field (in part because the determinants of what makes us healthy are so complicated). The science on food deserts is particularly weak, as is research showing that ubiquitous fast food causes diabetes.
Along the way, the report critiques a number of current projects in eight U.S. cities that seem to be counting a little too much on these simple narratives. The report questions a strategy in Los Angeles to build more transit-oriented development, which could actually wind up moving more people into the city's most highly polluted transportation corridors (trading one health problem for another). It dismisses a Chicago plan to build 17 grocery stores in low-income neighborhoods as an oversimplified solution to intractable obesity that will do little to dent it.
MIT also skewers Atlanta's BeltLine project for failing to consider the increased traffic pollution that people using its trails and parks would be exposed to. "In order for the BeltLine to function as a 'green lung,'" the report concludes, "vast new green space will be needed around the old rail line. This is economically and politically unfeasible in an area of higher density and land locked real estate."
A recurring thread throughout the report is one of humility: We don't know as much as we think we do, and there are certainly no silver-bullet design solutions for systemic public health problems. As MIT's Alan Berger, Casey Lance Brown and Aparna Keshaviah write:
The U.S. Centers for Disease Control and Prevention recommends a minimum of 150 minutes of aerobic activity at minimum each week. That regimen will not be met through increased stair climbing instead of elevators and slightly more walking between parking lots and office buildings. These examples point to the need for reliable, meaningful research on ways to have design more effectively impact urban health.
That's not to say we shouldn't try (the eight case studies in the report are full of recommendations on what Atlanta might do instead of the Beltline, or how Chicago could consider its health inequalities beyond food deserts). But perhaps it's a good moment to pause and take stock of what we can prove before old assumptions (cities are inherently unhealthy) simply get replaced by new ones (bike trails are good no matter where we put them – even next to congested highways).