Experts believe vitamins A, C, and E -- the so-called ACE antioxidants -- combat oxidative stress in the lungs that can lead to COPD.

CNN: Vitamin E may protect lungs

In California, Thomas Reeves, manager of public affairs and communications for ACE's regional rail commission, says officials have talked about ways to combat the tension, which he says is generally minimal, and even considered ending the program.

WSJ: Shhh! 'Quiet Cars' Turn Commuters Into Librarians