US Army became the largest user of gas masks just before the American entry into the First World War. After the attacks in France, there is no way a modern fighting force to be deployed against the Germans without the best equipment available to protect them from poisonous gas attacks.
Plants were churning out small amounts of gas masks for firefighters suddenly got a big order to fill in for American soldiers and their allies. The money came pouring into the industry that mushroomed overnight into a large business enterprise. You can know more about the gas masks from Gas Mask Pro.
British first built a respirator carbon monoxide used during World War One before the first use of chemical weapons by the Germans. Scientists have discovered that the enemy shells exploded giving off a very high level of carbon monoxide gas.
This level is found high enough to kill soldiers within 100 yards of the device unexploded in the trenches, foxholes, and small, protected area another patron in which carbon monoxide can concentrate further. The effect is similar to car exhaust when the car is left running in a closed garage.
It was a Canadian who designed a "smoke helmet" with a single blowing tube filled with a chemical solvent to neutralize chlorine gas used in attacks. Using this design, smoke helmet adapted by allied forces and is widely regarded as the first mass-produced gas masks used to be used against Germany.