No, not oxygen. I just wasn't sure if it was carbon monoxide. It very well could be, but I've been out of chemistry for too long to remember. Hydrocarbon + burning + oxygen = possibly carboon monoxide? I do know from using them at work all day long to heat our shop, that the propane heaters put out a LOT less fumes than a multifuel version of these sytle heaters and therefore, cause me less headaches. They do approve propane powered forklifts for indoor use for some reason....
Maybe I've been around these fume too long. lol.