It Keeps Reminding Me Of; "Spooks."

https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-54606692

Specifically Series 2, Episode 5;

http://www.bbc.co.uk/drama/spooks/series2_ep5.shtml

This was their submarine episode. Where the characters are locked together in a confined space as the tensions between them rise.

The excuse for this was a VX gas attack on London. Which you never know is real or not.

At one point the team's technical expert, Malcolm, breaks out the NBC PPE. Then goes on a long rant about how completely ineffective the masks will be.