I had periodic asthmatic attacks when cleaning clients' bathrooms. I was initially diagnosed with COPD. Yes, good ventilation is a must. In the US, we have a product called Shower Power -- effective, but oh so potent. Don't want to breathe it.
I'm happy to hear you're managing the pain, GT, but it would be so much better if these aches and pains our elders complained about when we were younger had not been visited upon us!
The New System! The New System . . .
https://www.buyshowerpower.com/products/shower-power
Shower Power is not your average bathroom cleaner or soap scum remover, it is formulated to save you time and leave your bathroom with a dazzling shine. Shower Power has a proven reputation of being tough on scum, hard water stains, mineral deposits and more. But don't take our word for it, scroll down to read what our fans have to say about it.