What's the health and safety issue with oxygen? It's not like it's a toxic substance or anything. When I'm burning out organic materials, like bugs or twigs, I often give the mold a shot of oxygen from my oxy-acetylene torch, with the acetylene turned off. That encourages stubborn residues to de-carbonize, and also helps push them out of the mold. Has oxygen been banned in Europe?
I'd be more concerned with the health and safety issues related to acetone, if you're using a lot of it for the vapor-smoothing process.