By Brent Stephens on May 1, 2014
We recently partnered with investigative reporter, Dave Savini, from CBS 2 Chicago to make air quality measurements in and around Metra trains and train stations in downtown Chicago. The Chicago Tribune had previously reported high concentrations of soot (black carbon particles) onboard trains over 3 years ago, which were thought to be caused by re-entrainment of diesel engine exhaust. We know that diesel exhaust emits a number of pollutants that are problematic for respiratory and cardiovascular health, including ultrafine particles, black carbon particles, metals, and VOCs and SVOCs. This report prompted Metra to take action, primarily by installing particle filters on the cabin ventilation systems (MERV 13 instead of MERV 8) and by installing (or planning to install) devices that shut-off the diesel engines as they enter stations. The filters were shown in 2011 to measurably reduce black carbon particle concentrations in the rail cars, which was good to see. I’ve also found links to documents showing that Metra was upgrading ventilation systems to include vent hoods on intakes and exhausts, manual closing of outdoor air dampers, and exhaust deflectors on the locomotives themselves. I’m not sure of the status of these repairs or the extent to which MERV 13 filters have been installed across the fleet.
UPDATE: Watch a video of the CBS 2 story