The Healthy City

If you live in the Chicago area, there’s a digital representation of you in a computer server on the UIC campus.

Over the past 12 years, Kouros Mohammadian, head of the civil, materials, and environmental engineering department, and his students have compiled millions of lines of computer code, plus statistical data from the U.S. Census and many other sources, to simulate the behavior, motivations, and movements of all 9 million area residents. The result is ADAPTS, the Agent-based Dynamic Activity Planning and Travel Simulation: a digital twin of the real city in which researchers can trace virtual residents on a minute-by-minute basis as they travel for work, rest, and play.

Combined with models capturing statewide travel patterns and national freight shipments, ADAPTS is a virtual laboratory, letting researchers study the impact of major changes—from relocating supermarkets to introducing e-scooter rental programs—on the way people move through the city and the downstream impact their travel decisions have on energy use, emissions, water usage, and public health.

“There’s a strong relationship between your travel and activity choices and your overall health,” Mohammadian explains. “The whole idea of building this digital city was to give us a space to test new kinds of infrastructure, and new policies and ideas, that will ultimately result in cleaner air, healthier cities, and healthier people.”

Engineers have been spearheading the effort to build healthier cities since ancient times, when they constructed Rome’s cloaca maxima and drained swamps to prevent malaria. In fact, modern urban planning has its roots in engineered solutions to cholera outbreaks in the 19th century, when industrializing cities built new sewage and water-treatment facilities, says Curt Winkle, an associate professor in UIC’s Department of Urban Planning and Policy.

Over time, urban planners shifted their focus, seeking to improve health by expanding access to hospitals and medical technologies. But in recent years, Winkle says, the pendulum has swung back. Much of the low-hanging fruit from medical interventions has been harvested, and engineers are once more taking a leading role in efforts to make cities healthier.

“Historically, it was engineering that allowed people to live together in dense urban configurations,” Winkle says. “For a long time, planners focused on medical models of public health, but now we’re once again realizing that the physical environment is vital to encouraging healthy behaviors and managing health risks.”

One area where engineers excel is in helping planners to better understand cities. “Cities are completely man-made, but because they’ve grown up over centuries or millennia, we don’t understand all the interconnected processes at work,” explains Sybil Derrible, director of the College of Engineering’s Complex and Sustainable Urban Networks Laboratory.

Clean air, unpolluted water, and sanitary waste disposal are all crucial to urban health, but they don’t exist in isolation. The power needed to pump clean water can itself be a cause of air pollution, for instance, while transportation systems can be both a source of emissions and a vital means of accessing healthcare. The result is a tangled network of cause and effect that is challenging to grasp in its entirety. “To build healthier cities, we need new ways of thinking about complex urban systems,” Derrible explains.

Derrible uses artificial intelligence tools to model interactions among urban systems such as water, energy, and transport networks, and to dream up more efficient and resilient ways of designing and managing urban environments. Sometimes the answers can be counterintuitive: for example, computer modeling suggests that modern cities might be better served by low-tech, distributed water networks like those used in the developing world than by the centralized, leak-prone water mains that many first-world cities have. In that sense, Derrible says, U.S. cities could learn from countries such as Vietnam, where buildings have individual water tanks, pumps, and even treatment facilities to ensure steady supplies of clean water.

Water isn’t tied to public health only with regard to drinking. In many cities, stormwater runoff triggers dangerous floods or washes toxic waste into municipal waterways, causing significant health problems. That’s where Krishna Reddy, a UIC professor of civil, materials, and environmental engineering and a specialist in remediating soil and water pollution, comes in.

At Rainbow Beach on Chicago’s south side, for instance, Reddy worked with the U.S. Environmental Protection Agency and the Chicago Park District to install an experimental stormwater-runoff filtration system. Using low-cost, easily sourced components such as calcite, zeolite, iron filings, and sand, Reddy’s filtration system removed virtually all the heavy metals, fuel, chemicals, bird excrement, and other noxious substances found in the water gushing into Lake Michigan. By reducing pollution to near zero, the filter allows the beach—which was closed for more than 100 days between 2010 and 2014 due to water-quality concerns—to stay open longer, giving local residents a clean, safe, health-promoting space for exercise and recreation.

Like clean water, air quality is a major health concern for urban residents, and not just due to emissions from busy city streets. In many cities, disused landfills were converted into parks or other common spaces, and fumes from decomposing waste still bubbles out into the atmosphere.

At one such site in the northern Chicago suburbs, Reddy’s team came up with an affordable, accessible solution, layering slag and biochar on top of the waste. The slag sequesters carbon while the biochar encourages microbial activity that digests methane and other fumes rising from the decomposing contents below.

“Practically nothing comes out—we call it a zero-emissions cover,” Reddy says. “You simply put biochar and slag on top of the landfill, then some soil for vegetation, and then you walk away.”

There’s no way to eliminate urban air pollution altogether, of course. That’s why Professor Jane Lin’s Sustainable Transportation Research Group is working to help people monitor and reduce their exposure to toxic fumes. Her team has developed a smartphone app called MY-AIR, which stands for “monitoring your air-pollution intake risk.” It uses information from air-monitoring stations around the city and mobile air-quality sensors, combined with personal activity data and local factors such as weather, land use, and traffic, to tell users precisely how much air pollution they’re exposed to from hour to hour.

Lin’s work on air pollution also is helping in the fight against COVID-19. She is seeking U.S. Department of Defense funding to study the way in which coronaviruses combine with other tiny particles in the air to form “bioaerosols” that float through built environments, especially indoors. As part of the project, Lin and her collaborators will use novel nano-material filters to extract virus particles from indoor air. They also will explore ways to use airflow data to boost the accuracy of contact-tracing methods.

“From nursing homes to submarines and airplanes, these technologies will keep people safer and healthier,” Lin says.

Innovations born at UIC are rippling out into the private and governmental sectors. One of Lin’s former PhD students, Sudheer Ballare, spent his time in the College of Engineering studying a new form of parcel delivery called “crowdshipping,” in which packages are delivered by pedestrians and private car drivers instead of trucks, reducing delivery-related emissions by up to 80 percent. Engineering isn’t just about redesigning the built environment, Ballare says. It’s also about employing new technologies to help us interact with that environment in healthier and more sustainable ways.

Ballare now studies vehicle emissions as a researcher with the U.S. Environmental Protection Agency. “The time I spent at UIC has been really valuable,” he says. “Once you’ve trained as an engineer, you can tackle any problem, anywhere in the world.”

Chicago’s top urban planners say engineers are key allies in the effort to design healthier cities. “A lot of the new thinking is coming out of universities like UIC,” says Jamie Simone, a UIC graduate who helped create The 606, an urban trail for bikers and joggers built along a disused elevated railway track. She now serves as deputy commissioner for the Chicago Department of Transportation. “We can partner with UIC for research work, and meet students there, and learn from them what’s coming next in the field,” she says.

UIC’s engineers are helping city leaders to dream bigger as they work to make Chicago healthier, Simone adds. “As planners, we rely on engineers to make our visions a reality. It’s a really important relationship.”