This is to extend the usage time of the gas masks.
Activated carbon gas masks purify the air by using carbon particles to adsorb the poisonous gas in order to achieve the goal of protection.
However, this does not mean it can be used indefinitely or repeatedly.
When it reaches a certain saturation point, its adsorption effect on the gas particles significantly weakens, at which point the filter canister needs to be replaced.
During combat, it's certainly impossible to call for a pause to allow French Army soldiers time to replace the filter canister.
Shire thought of a way to utilize the trenches.
The air in the trenches before reaching the front line is usable, though it's mixed with various unbearable smells: sweat, urine, and even excrement.
In this regard, England and the French Army have failed.
The trenches of the English and French Army are often in utter disarray, not only chaotic and disorganized, but hygiene and personal issues are also very serious.
