Some other guys and myself were working on putting a cellar or basement if you will under an existing house-we were using an old Case Uniloader,gasoline powered and the choke was about half stuck shut and the motor was running rich.In just a little while we were sick and drowsy,ended up with a terrible headache-CO is nothing to trifle with,CO will burn its not completly oxidised(thats what the the old gasogen motors burned) thank God for catalytic converters,of course the new Diesel engines for the most part use Urea(diesel fluid to breakdown the NOX) This may be a stupid question but what does the nitrous oxide hurt?-Kevin