Caroline Williams in her protective suit. (possible spoilers)

The only part of this movie that I have seen is on youtube where they are testing the gas on a rat in a sealed laboratory. Caroline Williams/Molly is in her protective chemical suit with full faced gasmask, as are 4 or 5 other scientists. When the glass tank gets broken they all start to die very horrible deaths. Strangely Caroline survives longer than all the others even though she was right next to the tank when it gets broken.

My wife and I have the exact suits and gasmasks (even with the corrugated breathing hose) and wear them when we work on the weekends in our garage when we are casting things/ornaments in some potent resins (only when in liquid form) to sell at local markets. The suits are hot and uncomfortable, hard to communicate in but we work away safe in our protective suits, safe from all splashes and poisonous fumes.

So I have two questions:
1. With such protective gear on, why did they die such deaths (or at all).
2. Could something similar happen to us. This we doubt as we did research what we were doing first.

Everytime we suit up to work in our suits and masks, we both have a laugh to each other as my wife quickly re-enacts Caroline struggling at her mask and I help her. Any response to the two questions would be appreciated as well as anything else, whether about the movie or the suits. Thankyou.