I’m one of those people who has to take extra care when dealing with poor quality air. In fact, I’ve not been to steam train things for a while now for this reason. I have also chosen not to go to theatrical and artistic events due to the warnings about vapour effects being used and the effect it could have on people with long term breathing conditions. I’m asthmatic, and have to be extra careful. Once, I couldn’t go into pubs and cafes and other public spaces without suffering badly during and afterwards. I was so glad when the law was changed to stop smoking - it opened a lot of doors for me which were closed. Given the problems I had working in a smoke filled office in the 1980s, where I had numerous emergency interventions at my GPs to relieve severe asthma attacks, I’m pretty glad that the air is now relatively clear.
Vaping is a problem, though. We still don’t fully know what the substances do, and what the issues around second hand “vapour” are yet. I tend to apply the same rule to that as I do with cigarette smoke - if I can smell it, it’s doing me harm (and, yes, I know - cigarette smoke can be harmful when you can’t smell it, especially in an enclosed space). I tend to hold my breath for as long as possible. I have yet to be convinced that the exhaust from a vaper is any safer than that from a cigarette smoker. It is certainly more than just vaporised water - the smell tells you that. If it was pure water, there would no odour.