i saw that happen to a friend competing in a 4 wd. truck race. he was strapped in with his helmet on waiting to be called up when he accidently pushed on the extinguisher. it was supposed to be safety pinned. anyway the cab fills up with yellowish smoke the door opens and he falls out. by the time he realized something was wrong he injested some of the crap and almost passed out. not a good experience. feets you were lucky it happened in a area where you could get off the road. could of been a lot worse.