By Courtenay Harris Bond & Amrita Balachandran

What if community parks offered free dance classes: Would people living nearby participate, and become healthier?

For Olga Lucia Sarmiento, an associate professor of public health at the Universidad de los Andes in Bogota, Columbia, the answer is yes.

Sarmiento was one of four presenters at the Urban Health Symposium session on research into urban policies and natural experiments, defined as “empirical studies in which individuals exposed to the experimental and control conditions are determined by nature or by other factors outside the control of the investigators.” When Bogota officials identified six new parks in which to install a physical activity program that had been in other parks throughout the city for more than 20 years, Sarmiento saw a chance to conduct a natural experiment about the impact of the policy on the health of individuals and their communities.

Her team took height and weight measurements of study participants, used accelerometers to gather data, conducted semistructured interviews with staff running the classes and reviewed literature about the program. They learned that the dance classes increased levels of moderate to vigorous physical activity and helped create community cohesion.

As a sociologist, Diana Hernandez didn’t know much about boilers - until she started studying the impact of New York City’s clean heat policies.

“I’m successful today if I make you or help you appreciate that sludge in boilers is problematic for the environment,” said Hernandez, an associate professor at Columbia University. “It’s also problematic for health and also has implications for disparities.”

The lived experience of dirty fuels is a “very real hardship,” Hernandez said. To illustrate this point, she quoted a subject from one of her studies: “It was like a volcano of black smoke that came directly into my kitchen window ... I realized immediately when it smelled like a city bus, like I was standing behind a city bus, that we needed to get the heck out of the apartment. I shut the window but it was too late ... I developed asthma in the same year, 2006. And I was 43 years old. I’d never had asthma in my life.”

Hernandez’s studies show how New York’s clean heat policies have impacted both the city’s environment and the health of its residents.

From 2012 to 2015, her team evaluated New York City’s efforts to get buildings to shift to cleaner fuels. What they found was that the implementation of the new policies was highly successful, with nearly 100 percent compliance over the course of three years. Air quality and community health improved, but researchers also found that compliance alone wasn’t enough. The laws needed strengthening to encourage more of the buildings to shift completely to natural gas.

Hannah Lawman, director of research and evaluation in the Philadelphia Department of Public Health’s Division of Chronic Disease Prevention, discussed her research into the efficacy of two public health policy “wins” for Philadelphia: last year’s passage of a beverage tax of 1.5 cents per ounce on all sweetened drinks and new tobacco retailer permit regulations that took effect this year.

The goal with the soda tax evaluation was to see what happens to consumption and price. To assess these factors, Lawman’s group examined millions of scanner records, conducted intercepts in stores, asking to inspect people’s bags, and made site visits to smaller shops in the city. They also conducted qualitative interviews. Lawman was set to present findings at the Obesity Society in November.

To evaluate the impact of new tobacco regulations designed to help control the density of tobacco retailers in Philadelphia and to create tobacco-free school zones, Lawman’s team analyzed a retailer database and used online panel surveys to ask people about their smoking habits and perception of retail environments.

“In Philadelphia, we see that people are just bombarded with tobacco,” Lawman said. Philadelphia has more sellers and advertising than many other cities and the highest youth tobacco sales violations in the state, she said.

Before she moved to the suburbs of Detroit in 2015, Roshanak Mehdipanah, an assistant professor of health behavior and health education at the University of Michigan, spent four years working with the public health department in Barcelona to evaluate the impact of the Neighborhoods Law.

Passed in 2004, the law created a massive urban renewal program aimed at improving the physical infrastructure, social integration and economic condition of residents of 143 neighborhoods in the region of Catalonia, Spain. At the time, it was the largest urban renewal project in Europe.

Using a mix of qualitative and quantitative methods, Mehdipanah’s team evaluated the perceptions of the program among residents in targeted neighborhoods, as well as assessing their health status before and after the intervention. The findings indicated that Neighborhoods Law intervention had improved self-rated health of residents and that urban renewal policies brought about the most significant improvements in health among the most deprived populations.

When a change in the regional government in Catalonia halted the implementation of urban policy improvements under the Neighborhoods Law, Mehdipanah’s evaluation of the program prompted vociferous community and media support. Two months later, the government resumed the program and later, expanded it.