Chicago's skyline is pictured in this file photo.

As the city experiences its latest heat wave, officials with the city’s health department are waiting for the results of a heat study conducted last month that could provide crucial information about how to prevent and mitigate heat-related deaths and illnesses in the city.

In April, Chicago was among 18 communities selected by the National Oceanic and Atmospheric Administration (NOAA) to participate in this year’s urban heat island mapping campaign, a project NOAA has undertaken since 2017 and which is funded through the NOAA Climate Program Office, according to a NOAA spokesperson.  

In a news release announcing the 2023 communities, NOAA explains that urban heat islands are “areas with few trees and more pavement that absorbs heat,” and they “can be up to 20 degrees Fahrenheit hotter than nearby neighborhoods with more trees, grass and less black asphalt.” 

Related: Stemming urban heat island effect requires more vegetation, greener roofs: officials

The program involved communities enlisting volunteers to travel multiple routes on one of the hottest days of the year in those respective communities. That day in Chicago turned out to be July 28, when the city experienced temperatures upwards of 106 degrees Fahrenheit at O’Hare Airport.  

Chicago’s Heat Watch Campaign, organized by the Chicago Department of Public Health (CDPH) and Office of Climate and Environmental Equity, deployed dozens of volunteer drivers and navigators in response to the extreme heat July 28 to collect temperature data in the morning, afternoon and evening along 29 routes that touched all 77 of Chicago’s community areas, CDPH Director of Environmental Innovation Raed Mansour told The Daily Line.

The data is collected by sensors, provided by CAPA Strategies, that are attached to cars or bikes. The sensors collect air temperature and humidity data every second. 

The sensors were sent back to CAPA Strategies in Portland, Ore. for analysis, Mansour said. He estimated the department will receive a completed heat map that shows the citywide temperatures at three different times of day by September or October.  

According to NOAA Climate and Health Communications and Outreach coordinator Morgan Zabow, this methodology for studying heat is used because it captures “a better picture of the human experience of heat.”

“There are other ways in which the urban heat island is studied,” Zabow told The Daily Line in a statement. “But many efforts, like satellite data and land surface temperature, do not represent the human experience of heat, which needs to also look at air temperature, humidity, wind, and more.”

During the planning stages for the program, project leaders invited the public to submit locations for an online map to indicate particularly warm and hot spots in the city. The routes, which are about a mile each, were developed in a way so that the drivers would hit many of these pinned locations, Mansour said.

Each route also covers a diversity of locations themselves, Mansour explained.

“So the urban heat island, in order to do a respective comparison in the city, you want to pick up the cool areas and the hot areas,” Mansour said. “So you can see the differences within communities but also neighborhoods.”

Routes include lakefront streets, industrial areas, areas with varying levels of development, alleyways, streets with heavy tree canopies and completely exposed parking lots.

“This way we can see the relative difference and we could visualize that disparity basically and see how different communities experience heat differently,” Mansour said.

Joey Williams, Urban Heat Island mapping campaign manager for CAPA Strategies, said the data has often revealed that communities with more disinvestment and less tree cover, often communities of color, are experiencing higher levels of heat.

“We see redlining show up very commonly as a correlating variable with heat disparity, and of course also socioeconomic status and health impacts,” Williams said. 

After analysis of the Chicago data is finished, Williams said the city will be sent a summary report, an online interactive map of the heat disparities and access to the raw data itself.  

The information revealed by the heat map and report will be used to create a heat vulnerability index and to propose policy solutions for the heat disparities, Mansour said.

One of the solutions could be as simple as increasing the tree canopy in undercovered areas — Chicago has an ongoing effort to do just this. The city could also install additional splash pads and water features in areas that lack them, Mansour added.

Another solution could be the creation of a neighborhood-wide alert system for areas that are particularly susceptible to increased heat levels even when the whole city is not under a heat advisory. 

“One of the causes in the 1995 heat wave that killed over 700 people was the socially isolated,” Mansour said. “What if we create a neighborhood-level type of heat warning, where we don't activate the entire city, but we activate the areas where there's vulnerable people, and the community can do wellness checks.”