nicolai
Appreciate the info, thanks. The key thing here appears to be that we are talking about fumes from combusted oils, the properties of which are totally different from the fumes from the same oils in a non-combusted state.
Incidentally I asked the question because we live in a city where there are thousands of 2-stroke motorcycles on the road, the fumes from these beasts are pretty horrendous sometimes so it is a matter of concern to us.