That\u2019s why, a day before the smoke plumes descended, Saxon was using zip ties to fasten an air quality sensor to the railing of a house in McKinley Park, the latest of 15 or so installations she\u2019s done over the past few years. Her goal is to monitor pollution from the asphalt plant.<\/p>\n
\u201cI love this neighborhood so much, but if you were here yesterday or the day before around this time, it would smell like burning asphalt,\u201d she said. \u201cIt was almost unbearable to be outside.\u201d<\/p>\n
Air quality in Chicago is measured in different ways, from fairly cheap sensors such as the one Saxon installed to the sensors in the network set up last summer<\/a> by the city of Chicago and University of Illinois Chicago. Then there are the sophisticated regulatory monitors that are much more expensive and complicated to use.<\/p>\n UIC professor Serap Erdal, who leads the Open Air Chicago project, said it\u2019s the second-largest air monitoring network of its kind in the world behind London.<\/p>\n But even then, the sensors only measure static points spaced throughout the city. In the future, satellites could fill gaps in air monitoring coverage for the city and the many regions of the country where there is no coverage, according to recent studies.<\/p>\n Yet some advocates say better air quality tracking still doesn\u2019t do enough to address the root causes of pollution.<\/p>\n \u201cOur goal is not to know how bad the air we\u2019re breathing is,\u201d said Anthony Moser, board president of Neighbors for Environmental Justice, a community group based on the Southwest Side. \u201cThe goal is to breathe clean air.\u201d<\/p>\n Neighborhood air sensors<\/p>\n Saxon, 39, is a community science organizer at the environmental advocacy group. It focuses especially on the MAT Asphalt plant in McKinley Park. Ever since opening in 2018, the plant has faced criticism<\/a> over its proximity to a school, major public park and homes.<\/p>\n Saxon said she\u2019s installed sensors manufactured by PurpleAir in McKinley Park and other neighborhoods with elevated levels of air pollution. These sensors cost $289 each, according to PurpleAir\u2019s website. Saxon said the monitor she recently installed was purchased with a grant from UIC.<\/p>\n Data from these sensors is available to the public online.<\/a> The sensors measure a few things, including fine particles known as PM2.5.<\/p>\n PM2.5 can be emitted by factories, power plants, diesel and gasoline vehicles, residential fireplaces and wildfires. The fine particles can harm human health and sometimes be deadly.<\/p>\n The sensor freshly installed by Saxon on July 15 first showed a PM2.5 rating of 58 \u2014 then jumped to 71 two minutes later.<\/p>\n Both numbers are within a range PurpleAir lists as acceptable, but the website details potential risks with a full day of exposure, especially for people unusually sensitive to air pollution.<\/p>\n As Cook County filled with record-breaking PM2.5 levels from wildfire smoke on July 16, the sensor read 595. AirNow<\/a>, a website that combines data from county, state and federal air quality agencies nationwide, reported PM2.5 levels in similar ranges in Chicago that night.<\/p>\n Anything above 300 is considered a \u201chealth warning of emergency conditions.\u201d These conditions are hazardous to everyone.<\/p>\n In September, Chicago and UIC finished installing sensors for Open Air Chicago. Solar-powered sensors were placed on light poles across the city.<\/p>\n Industrial neighborhoods with a heavier pollution burden identified by the Chicago Environmental Justice Index<\/a> received more sensors. Thirteen organizations, one of which was Neighbors for Environmental Justice, helped decide sensor locations. Many of them were placed near daycares, schools and hospitals, according to UIC\u2019s website.<\/a><\/p>\n Erdal said findings from Open Air Chicago aren\u2019t ready to be shared yet.<\/p>\n Angela Tovar, the city\u2019s chief sustainability officer, said the city\u2019s sensors are not used to enforce air quality regulations but instead give residents real-time information about the air in their neighborhoods.<\/p>\n \u201cIt\u2019s an important tool as we talk about air quality. We want people to understand the data in their community,\u201d Tovar said. \u201cWe\u2019ve even used that as a resource as recently as last week during the wildfires, making sure people knew there was a tool that could show, at a very granular level, what air quality looked like in their community.\u201d<\/p>\n She said the network helps city officials identify pollution patterns that could inform future enforcement plans.<\/p>\n \u201cIt certainly allows us to see trends and concentrations of air pollution that we should be concerned about,\u201d she said. \u201cThat could help inform future strategies for how we approach enforcement across the city.\u201d<\/p>\n Residents who want to check the air quality in their neighborhood can go to the Open Air Chicago map<\/a> and click on a sensor nearest to their location to find readings on pollutants.<\/p>\n Erdal said a website for Open Air Chicago will launch in the next few weeks with sensor data and educational resources.<\/p>\n \u201cThe website not only will serve as a data-dissemination platform, but most importantly, it will also serve as a community education platform,\u201d Erdal said. \u201cWe are trying to really make the data to be useful, understandable, to the public.\u201d<\/p>\n Within legal limits<\/p>\n Even though Open Air Chicago is operational, Neighbors for Environmental Justice members still install their own air sensors. That\u2019s for a few reasons. Moser said although the city\u2019s air sensors are \u201can achievement,\u201d they can still be a mile or more apart, leaving gaps in coverage.<\/p>\n The environmental advocacy organization also started installing sensors before Open Air Chicago put up its own devices and made the data publicly available. Additionally, showing people data on their own streets or homes can help air pollution seem more tangible, Moser said.<\/p>\n \u201cI find (sensors) to be a compelling way to get people to engage with the idea of air pollution as a real thing,\u201d he said. \u201cIt\u2019s easy for it to be kind of invisible.\u201d<\/p>\n The relationship between Chicago\u2019s asphalt plants and air pollution is well documented, Moser said, and knowing the levels only does so much.<\/p>\n Zoning and planning laws also make it easier for developers to build in certain neighborhoods, particularly in communities where many residents are low-income and people of color, Moser said.<\/p>\n MAT Asphalt facility manager Joe Haughey said he gets calls regularly from a member of Neighbors for Environmental Justice complaining about odors coming from MAT Asphalt.<\/p>\n \u201cI\u2019ll say, \u2018Where are you standing, what intersection? I don\u2019t need to know your home, but I would like to meet you somewhere in the area where you\u2019re smelling this,\u2019\u201d he said. \u201cNot once has that person ever taken me up on that.\u201d<\/p>\n Haughey pointed to testing showing MAT Asphalt was well within legal limits for emissions. According to a 2022 MAT Asphalt news release, CleanAir Engineering, a testing and consulting firm in Palatine, found the plant\u2019s particulate matter emissions to be less than 1% of permitted levels.<\/p>\n Haughey said if parts of McKinley Park have noxious odors, it\u2019s due to sources other than MAT Asphalt.<\/p>\n \u201cI personally believe odors are a chosen complaint because of how arbitrary they are, meaning no one is going to tell somebody that they didn\u2019t smell anything,\u201d Haughey said. \u201cIt\u2019s a very hard thing to prove if someone is being disingenuous about what they smell.\u201d<\/p>\n Truck traffic<\/p>\n A lot of air pollution doesn\u2019t come from plants but from industrial corridors in the city and suburbs where large trucks bring materials in and out. Little Village<\/a> and south suburban Elwood<\/a> residents are among those who have organized after diesel emissions near their homes were predicted to increase significantly because of warehouse developments.<\/p>\n A state bill requiring emission targets and buffer zones between warehouses and nearby neighborhoods failed to advance in the General Assembly\u2019s spring session.<\/p>\n Baltazar Enriquez, president of the Little Village Community Council, said the group organized a commission focused on improving air quality in the community.<\/p>\n \u201cWe\u2019re fighting for our children to have a place to play, and they\u2019re, later down the road, not going to be diagnosed with asthma or lung problems,\u201d he said.<\/p>\n Air monitoring is also on his mind. Enriquez said the community has PurpleAir sensors set up. But these sensors can only detect so much, and he said some haven\u2019t functioned as they should due to the weather or being incorrectly calibrated.<\/p>\n \u201cWe want a more efficient air monitor that detects everything,\u201d Enriquez said.<\/p>\n Sensors vs. monitors<\/p>\n Chicago has six federal air monitoring sites, according to the city\u2019s website. These sites contain \u201cregulatory monitors\u201d more sophisticated than the sensors used by the community group and Open Air Chicago.<\/p>\n \u201cIt takes, you know, a very well-trained person, a chemist, to operate and interpret these instruments, but they\u2019re both accurate and precise,\u201d said Zac Adelman, executive director of the Lake Michigan Air Directors Consortium.<\/p>\n Regulatory monitors are used to \u201cassess compliance\u201d with federal air quality standards, according to the city of Chicago\u2019s website. Adelman said there\u2019s not many regulatory monitors due to how expensive they are.<\/p>\n That makes the cheaper sensors an attractive option for many. Adelman even has one from PurpleAir attached to his house. However, he said there are limitations to tracking air quality with sensors.<\/p>\n The ability for sensors to accurately measure air pollution is lower, and they\u2019re more vulnerable to environmental conditions such as temperature or humidity changes, Adelman said. Sensors that show up on a public map could be placed anywhere.<\/p>\n \u201cWhen you look across the PurpleAir map, sometimes you see sensors that are reading, like, anomalously high compared to the other sensors in the map,\u201d Adelman said. \u201cThat could be in somebody\u2019s kitchen or on top of their barbecue.\u201d<\/p>\n Satellite tracking<\/p>\n Another issue is there\u2019s just not enough regulatory air monitors to measure the whole country.<\/p>\n \u201cThere\u2019s more than 3,000 counties in the U.S., but less than 1,000 of them have any kind of monitoring at all for one of these pollutants,\u201d said Kevin Stewart, director of environmental health for the American Lung Association.<\/p>\n![\"Sonia](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS06_264778497.jpg\")
Sonia Monet Saxon, community science organizer at Neighbors for Environmental Justice, installs an air quality monitor at a home in the McKinley Park neighborhood on July 15, 2026. (E. Jason Wambsgans\/Chicago Tribune)<\/p>\n![\"Sonia](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS01_264778467.jpg\")
Sonia Monet Saxon, community science organizer at Neighbors for Environmental Justice, installs an air quality monitor at a home in the McKinley Park neighborhood on July 15, 2026. (E. Jason Wambsgans\/Chicago Tribune)<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS07_265037659.jpg\")
An air quality sensor that is part of the citywide network Open Air Chicago hangs on a pole on July 24, 2026. The system is run by the Chicago Department of Public Health and the University of Illinois Chicago. (Terrence Antonio James\/Chicago Tribune)<\/p>\n![\"Pipes](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS-2-03_265012353.jpg\")
Pipes that connect silos at MAT Asphalt are visible from across the 2000 block of West Pershing Road at the south end of McKinley Park as area resident Cuitlahuac Arriaga rests on a hill on July 23, 2026, in Chicago. (John J. Kim\/Chicago Tribune)<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS-2-08_265012359.jpg\")
An asphalt truck passes a jogger running along the south end of McKinley Park, across the street from MAT Asphalt in the 2000 block of West Pershing Road on July 23, 2026, in Chicago. (John J. Kim\/Chicago Tribune)<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/07\/CTC-L-AIR-MONITORS08_264778563.jpg\")
An air quality monitoring website shows monitors collecting data in the McKinley Park neighborhood, July 15, 2026. (E. Jason Wambsgans\/Chicago Tribune)<\/p>\n