This story is written by Grist chicago public mediaa public media company serving the Chicago metropolitan area.
Serap Erdal stopped at a utility pole in Chicago’s Grant Park, pulled out his cell phone and began pinching the screen. As she looked at the palm-sized map of the city, towering skyscrapers cut out the clear blue sky behind her. The researcher barely noticed the noise of city buses, cars and bicycles whizzing around her in the city’s crowded downtown. She was practicing something in the cool summer air.
Fixed to a pole above her was one of the city’s new solar-powered air quality monitors. The tracker, encased in a silver metal shell about the size of a tissue box, is part of the nation’s largest community air quality monitoring network. The network currently has 277 air quality monitors across Chicago, collecting air pollution data from every borough and community area, with increased concentration in already overburdened areas.
A bright green dot flashed on Erdal’s cell phone. she smiled.
“Right now, the air quality index here is 31,” said Erdal, a professor of environmental and occupational health sciences at the University of Illinois at Chicago. This reading means air quality in the city’s public parks is in the Environmental Protection Agency’s safest category, posing little or no risk to public health. “It’s sunny and windy today, so the concentrations across the city are very even,” she added.
On that day in June, almost every monitor in the city was green. However, all but one on the south side had emissions flowing into nearby black and Latino neighborhoods from old industrial facilities and freight transportation. Over the next few years, monitoring systems are expected to shed light on dramatically uneven air quality in different regions, even on sunny, breezy days.
Serap Erdal shows a map of Open Air Chicago on his cell phone. Erdal helped launch the project last fall. Tyler Pasiak Lariviere / Chicago Sun-Times
The project, called Open Air Chicago, went live last fall and is part of a five-year project to collect hyperlocal air quality data and provide real-time pollution information to Chicagoans. The data is also intended to help authorities develop guidance on permitting, urban planning and air quality management. The network is heading into Chicago’s first summer, when air pollution typically worsens. Pollution from cars, heavy vehicles, and industry reacts with sunlight and heat to form ozone on the ground, a harmful pollutant and main component of smog in summer. As summers become longer and hotter due to climate change, conditions that produce smog are also becoming more common.
The surveillance effort began as a result of a dispute over the city’s decision to move General Iron Co.’s scrap metal crushing operations from the predominantly white Lincoln Park neighborhood to the predominantly Latino and black Southeast Side. In 2021, local environmental activists filed a civil rights lawsuit with the federal Department of Housing and Urban Development, claiming the measure discriminates against and harms the health of low-income communities of color.
The city and community groups reached a settlement that includes the launch of a regional air monitoring network in 2023. Chicago officials partnered with the University of Illinois at Chicago to launch it last fall at a total cost of more than $4 million to cover operations through early 2030.
“This air monitoring system creates a continuous record of Chicago’s air quality,” said Oscar Sanchez, director of the Southeast Environmental Action Council, one of the groups that filed the civil rights lawsuit.
On June 1, the Southside Avalon Park area had the highest air quality index in the entire city.
Tyler Pasiak Lariviere / Chicago Sun-Times
Until now, residents of the South and West Sides had limited ways to prove their air was unsafe. They tend to have higher rates of respiratory disease, but there was a lack of time-stamped data to establish a link between poor health and local air quality. Sanchez said the surveillance system will make a difference.
“This is something Chicago is working on in good faith,” he said. “We’re here to make sure information is out there so people don’t have to worry about their experiences.”
The distance between each air monitor is less than a mile. This low-cost device measures ground-level concentrations of two air pollutants. One is nitrogen dioxide, which is usually produced by burning fossil fuels, and the other is PM2.5. PM2.5 are tiny particles, just one-twentieth the width of a human hair, that can pass through a person’s respiratory system and into the bloodstream. Exposure to both pollutants has been linked to childhood asthma and cardiovascular problems. PM2.5 is increasingly highlighted as a major environmental health determinant worldwide, associated with acute mortality and morbidity in respiratory and cardiovascular health conditions.
Although air quality has improved in recent decades, it can still reach unhealthy levels during the summer months as sunlight and warm temperatures react with pollutants in the air to form ground-level ozone. Seasonal smog can mix with smoke from increasingly frequent wildfires, further worsening air quality. Daniel Horton, an assistant professor of earth and planetary sciences at Northwestern University, says climate change is exacerbating the situation in the Midwest.
“We must also address the effects of increased wildfire frequency and intensity,” Horton said. “This isn’t necessarily a problem in our backyard, but when the wind blows in the right direction, we suffer from the effects in the Midwest.”
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Wildfire smoke is definitely turning Chicago’s summer skies a hazy orange color right now. Smoke from record Canadian wildfires reached the Windy City in 2023, raising ground-level ozone levels by nearly 10 per cent above federal pollution standards, according to research published earlier this year. The study also found that areas in central, west and southeast Chicago are most affected by ozone.
So far, wildfires have already burned 2.5 million acres across the United States. This is almost double the average for the past 10 years for this time of year. A recent study published in the journal Science earlier this month says the recent spike in wildfires is partly related to climate change, reversing the country’s steady progress toward improving air quality.
The study found that from 2003 to 2015, stricter federal air quality rules succeeded in reducing the toxic gases that form ozone (smog) by about 11 percent. But since 2015, rising ozone levels have wiped out about a third of the country’s progress towards cleaner air, resulting in 318 more premature wildfire-related ozone deaths per year since 2013.
A jogger runs along the shores of Lake Michigan in June 2023, with thick smoke from the Canadian wildfires in the background.
Kamil Krzaczynski/AFP via Getty Images
Horton said that as air pollution in the Midwest and across the country is being reshaped by extreme heat, Open Air Chicago’s network can identify local pollution hotspots and provide an “unprecedented look into the state of air quality across the city.”
The local network is expected to build on existing data collected by NASA satellites and the EPA’s limited number of regulatory-grade air monitoring sensors, which Horton calls the “gold standard.” The EPA’s more sophisticated monitoring equipment more accurately measures pollutants such as PM2.5 and nitrogen dioxide, but is also more expensive to maintain. Chicago’s low-cost sensors capture more than 20,000 data points per day, albeit with less accuracy. The vast amount of data is expected to yield important discoveries about how air quality changes across cities.
Karl Mullins, a research associate at Morgan State University and NASA Goddard Space Flight Center, said the in-field data is especially important because satellites often take aerial images that combine the messy interactions of particles and gases across the layers of the atmosphere, making it difficult to resolve the components in the air people breathe near the Earth’s surface.
“If you see smoke rising from satellite data without any other information, it can be difficult to determine whether that smoke is actually reaching the ground and impacting air quality and people’s health, or whether it’s just rising above the ground and passing overhead,” Mullins said.
Grace Adams, a project manager for the Chicago Department of Public Health, looks at one of the individual air sensor readings on her cell phone. Tyler Pasiak Lariviere / Chicago Sun-Times
Back in downtown Chicago, Erdal said the program is scheduled to run through 2029. City officials hope to keep the network online for much longer. Beyond the noisy downtown traffic, she said the network is the culmination of 20 years of citizen-based research with communities on the city’s West Side and Southeast Side. Previously, she worked on a project to monitor vehicle emissions in several of the city’s Latino-majority neighborhoods, including helping local environmental justice activists install low-cost PurpleAir sensors.
Now, her big goal is that the data collected over the next five years will help create a roadmap for city officials and community leaders to reduce Chicagoans’ exposure to hazardous air.
“We hope to be able to strengthen the network in the future,” Erdal said. “Measure more pollutants and provide more data to the public.”
