Too late! LOL. I've sat by fires plenty of times. The machine itself is kept well away, at least 25 feet. But if I'm wearing the tubes, I have sat as close as 3 feet to a fire with no problem. These have all bee "contained" fires, in fireplaces. Haven't sat out by an open campfire, because I haven't had electricity near one yet.
I'm also not supposed to wear it while using a heating pad, or on a bed with lots of pillows and blankets. I do that, too!
I think the main issue is not letting anything like clothing become overly saturated with oxygen and then getting those too hot so they combust. If I were to (continue) to be careful about that, I think it would be okay. If I'm not actually wearing a tube, I turn the machine off, rather than let it "leak" all over and get anything to a flammable point.