Attached is the link to the 2011 Illinois Annual Air Quality Report from the Illinois EPA. In it, it quantifies the pollution from 2011 with respect to the major categories that are monitored. Several Sample bits of information are as follows
This is a map of where the air quality sensors are located within Cook County. One thing that is obvious is that there is not enough sensors within the actual City of Chicago. Most of these sensors are on the periphery of the city.
This is the breakdown of the number of sensors within all of Illinois. One problem is that there are only 1 CO2, 5 Particulate matter, and very few of the other important sensors throughout the state.
Here are the sampled days. The samples are taken every 3 days.