Do car fumes ever bother you when you're biking?
I get extremely frustrated when I'm biking, trying to catch my breath, and I get stuck in a huge cloud (sometimes a full block in length) of car fumes or truck diesel fumes. There's nothing worse, in my opinion, when you're exhausted from pedaling hard and you take a deep breath to get some oxygen into your system and you end up inhaling toxic chemicals and carbon dioxide (or whatever it's called) that makes you even more tired. It's one of the reasons I stopped commuting by bike and stopped biking during the day altogether. Now I mostly ride at night.