You're breathing those fumes if you're in an auto stuck in traffic, too! At least on a bike, you're passing the zone rather than waiting in it (but probably breathing more too). If possible, I'd look to ride on side streets to avoid it, but I do think that the exercise benefits generally outweigh the exposure risk. As you get used to cycle commuting, you'll probably cut your time down. I take that as 55 minutes round trip. If you're at 55 minutes each way an electric assist might be a life changer; where it might merely be nice to have at less than 30 minutes each way.