Take a deep breath: ‘Open Air Chicago’ map provides real-time air quality data

Hundreds of tiny air-quality sensors are tracking pollution across Chicago’s neighborhoods, and the data is now at your fingertips.

The Chicago Department of Public Health has launched “Open Air Chicago,” a new online tool that lets residents check hyperlocal air quality in their neighborhood. The city says it’s powered by 277 sensors that were installed in every ward last year, designed to provide estimates of common pollutants linked to traffic and other emissions.

“They provide hyperlocal estimates of different pollutants…so that’s NO2 (nitrogen dioxide), PM2.5 (particulate matter), like soot,” said Grace Adams, a project manager with CDPH who led the sensor rollout.

To use the new tool, residents can open the “Clarity Map” on the health department’s website, type in an address, and view color-coded air quality markings in that area. The map also provides automated guidance on what steps to take if air quality drops.

On Friday, most of the city was in yellow, or “moderate” status, a level she described as generally acceptable but worth monitoring.

“Moderate status is still okay,” Adams said. “You might want to keep an eye on it.”

Adams said the system has already detected short-term increases tied to colder weather patterns, when more residents idle vehicles and heating systems run more frequently.

“With the colder days that we had just in the last couple of weeks, we saw some higher spikes because cars were warming up outside,” said Adams. “There were furnaces going.”

City officials say the Clarity Map is especially important for people who are more vulnerable to pollution, including those with asthma or other respiratory conditions. They also point to extreme events like last summer’s smoke from Canadian wildfires, when air quality in Chicago deteriorated quickly.

Dr. Serap Erdal, an environmental and occupational health sciences expert at the University of Illinois Chicago, said the project can help residents reduce exposure and protect their health.

“It empowers the residents to take action to reduce their exposures and to protect their health,” Erdal said.

Erdal emphasized that the new sensors are not a replacement for federal air monitoring stations, which use regulatory-grade instruments. Instead, she said, Chicago’s network should be viewed as additional context, offering more localized insight than broader regional monitors can provide.

The program is expected to run for at least five years.

Funding for the program came from grants and bonds, according to CDPH.