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The allure of Denver's 300 days of sunshine is hard to resist. But this cherished sunny climate comes with a tradeoff: increased UV radiation levels in a city lacking robust shade design infrastructure.

According to the , in the U.S., more people are diagnosed with skin cancer each year than all other cancers combined. In Colorado, it’s the sixth most diagnosed cancer in the state. And while city planners and public health organizations have worked to enhance human health initiatives through advancing neighborhood walkability and bikeability in urban spaces, sun safety considerations, which increase with outdoor activity, have often fallen short.

Last summer, the Community Engagement Design and Research Center (CEDaR) partnered with the Colorado Department of Public Health and Environment (CDPHE) to explore the connection between sun exposure, skin cancer and the built environment, and work towards building sun-safe communities in the Mile High City.

Assistant Teaching Professor and CEDaR Research Associate Sara Tabatabaie has been involved with this work for nearly ten years and first conducted shade audits for neighborhoods in Denver as a PhD student. “At that time, it was part of my and ,” she said. “We did it for the CDPHE, but it was a small version. They contacted us again a year and a half ago, and they asked whether we could do it for the whole city.”

The project team, which consisted of Tabatabaie, Associate Professor and CEDaR Co-Director Jota Samper and four ENVD student interns: Logan Shockey, Cameron Cooper, Carl Eberly and Theodore Johnson Mencimer, worked to develop a methodology to assess sun exposure levels across the city. This required completing extensive shade audits within neighborhoods that varied across socio-economic level and built environment amenities.

To complete the audits, the team surveyed public areas like sidewalks, trails and urban parks at different times of day. Audits specifically noted and mapped both walkability of the blocks as well as objects that cast shade, whether from a cluster of trees or from a built structure. They also noted the physical activity within each neighborhood to better understand how often people use outdoor, sun-exposed spaces. 

The shade audits evolved into comprehensive shade models for the entire city. The team used ArcGIS to map shade from both trees and buildings, combining these into a shade factor for each neighborhood and block group. Through integrating shade, walkability scores and socio-economic status information, the team calculated the sun risk index for each neighborhood and block group within neighborhoods to help prioritize areas for shade improvement. 

According to the resulting maps, neighborhoods with high physical activity coupled with insufficient shade structure, which heightened risk of UV exposure, fell mainly to marginalized communities. In many cases, these at-risk neighborhoods also had higher percentages of children, a group that is particularly vulnerable to the impacts of radiation.

“Maybe not surprising, but disheartening, is this idea that the poorest neighborhoods are the ones who need the most intervention in these areas,” Samper said. “It's the ones who actually need the most shade that get the most exposure.”

Currently, Denver does not have a shade auditing component embedded within its Health Impact Assessment, a process that helps identify built environment impacts on community health. The CEDaR team hopes that the results of this study can be a first step in conducting comprehensive health assessments across Denver. They also believe that the CDPHE can use this research and the team’s recommendations as a policy leverage to support existing urban forestry initiatives, enhance streetscaping guidelines and direct more funding to the neighborhoods that need it. 

“We know that what we are doing has a positive impact for the city,” Tabatabaie said.

Samper and Tabatabaie also recognized the positive impact the project had on the team’s student interns. The students were given the opportunity to gain field experience, learn and apply GIS mapping, support data analysis, provide input into the final report’s design and create connections within a government entity. CEDaR hopes to hire more student interns in the future to continue the next phases of the project.

“This is just the first phase of the project, it was about assessing,” Samper said. “The others will be about changing policy. And in the future, it will be about developing prototypes, designing and building things. It’s the entire spectrum of environmental design experience.”