The agency conducted air quality monitoring at Union Station for three weeks during June and July, taking measurements throughout a 12-hour period from 6 a.m. to 6 p.m. The EPA also conducted testing on nearby streets for comparison. In total, investigators undertook 101 tests, 64 on the platforms and 35 background tests.
The results, released on Thursday, show that the train platforms have an increased concentration of particulate matter, ranging from 23 to 96 percent higher than nearby streets. The levels were highest during rush hours and on the south platforms, and were also elevated closer to the locomotives.
Particulate matter consists of liquid droplets and particles smaller than 2.5 micrometers in diameter. Because of its small size, it can cause health problems for several vulnerable groups, including asthmatics, as the particles travel deep into the lungs.
The agency is seeking to remedy Union Station’s air quality through partnerships with Metra and Amtrak, amongst others, and by optimizing and upgrading the station’s ventilation system.