Engineers in my line of work have to deal with loads of issue with fire extinguishers but the one long running issue noone has cured is rotten eggs!
What have rotten eggs got to do with fire extinguishers?
Well…. Cartridge fire extinguishers have to be opened each service session to inspect the internal part how ever most when opened up let of a strong smell of rotten eggs, Normally this smell is caused by sulpher.
Fire extinguishers only contain Water (H2O) and carbon dioxide (CO2) and no sulpher !

So, you may ask, What causes the smell?
As it turns out its caused by the CO2 ! Apparently when CO2 rises to above 5% it becomes an hallucinogen, and most people exposed always think the smell Rotten eggs (for me its most of the time). If a test machine could be hired cheaply I could verify this but alas that’s an impossibility.

There’s plenty of information on this but if you want to know what triggered this line of thought it was a program by the BBC.