During my apprenticeship. In week 1, introduction week, we had all day, everyday, health and safety lectures. We were told it was a tedious week, but if we took on board the health and safety message we would have a happy and safe life and career.
My safety lessons had actually started well before this, my great school woodwork craftsman / teacher had already taught me a sharp blade, knife / chisel can never cut you if your hands are BEHIND the blade. A lesson I always observe to this day, which makes me a bit slow and cack-handed when cutting veg. etc.
What did my introduction week teach me.
1. Personal responsibly for safety - Don't do anything without making an intelligent assessment on safety issues.
2. Safety of others. Make sure not only what you do is safe, but is also providing a safe environment for those around you.
Now, I have every sympathies for this unfortunate woman and also the tremendous guilt and suffering her daughter must be going though. IMHO personal events like this that have tragically happened, do not absolve the person from their personal responsibility to be safe and to be safe to those around you.
If you don't understand the substance what you are working with, then refrain, or look it up on the fregin Internet, that is what it is there for.
A good example of this was the post a few weeks a go on that unfortunate bloke welding a diesel tank and and the poisonous gas, that has completely destroyed his life. He had the decency to inform others of his unfortunate situation.
My next door neighbour had asked me to repair an oven seal for them, before I would do this. I Googled possible glues and their effects / fumes at high temperatures. Next door neighbour repaired it himself, the same person that drove with Merc in winter mode all the time until gearbox complained, and went into limp mode and I had to sort out and his granddad was helmsman on the Titanic