Man,

I don't know about using it in a closed enviromnent. You aren't going to breathe too well for too long, imo. Sitting behind a bus at a red light is more than I want to be exposed to.

Also, be careful where you are using it.
A neighbor of mine (NJ State trooper) had a kerosene heater in his garage last winter and damn near burned his house down when he loosened a pressurized gas line on his Harley. Torched his garage pretty good and he suffered severe burns to his hands. Needed a bunch of skin graft operations, but is back to work.