Trying to get a handle on how much diesel pollution is being pumped into the air by Chicago's cars, trains and trucks is serious work.
Over the past few months, an air monitor has been set up in popular public places, including the Shedd Aquarium and in Chicago neighborhoods such as Pilsen, which until a few years ago was home to one of the dirtiest coal power plants in the country.
Susan Mudd, senior policy advocate with the Environmental Law and Policy Center, says the focus has moved from coal to diesel pollution to help assess the risk.
"Diesel pollution is very dangerous for people's health," she states. "It is linked with asthma, COPD - it's even linked with some cancers."
The Environmental Protection Agency tried to collect data on diesel pollution in Illinois a few years ago, but those samples were deemed unusable.
Mudd says her group's project is too narrow to replace the EPA's work, but she hopes it will give people an idea of how and where diesel emissions are affecting residents.
Later this year, when the Environmental Law and Policy Center is done collecting air samples, Mudd says a chemist will run through the numbers help identify diesel pollution hotspots.
"The other important reason for us to have a monitor is to help citizens learn about air pollution, and over time hopefully figuring out things that can be done to reduce the asthma and other health problems associated with diesel pollution in Chicago," she says.
Diesel pollution is not known to cause asthma, but it can make the problem worse. Compared to the preceding few years, the Centers for Disease Control and Prevention says asthma rates, especially among children, are at a new high.