The US Army became the largest gas mask user prior to America's entrance into World War One. After that attack in France, there was no way a modern fighting force was going to be deployed against the Germans without the best equipment available to protect them from poisonous gas attacks. Plants that put out a small number of gas masks for firefighters suddenly have a large order to be filled for men fighting America and its allies.
It was a Canadian who designed the "smoke helmet" with a single tube exhaling filled with chemical solvents to neutralize the chlorine used in gas attacks. Using this design, the smoke helmet was adopted by the allied forces and is widely considered to be the first mass-produced military gas mask employed for use against the Germans. You can find more about the best military grade gas mask on https://www.gasmaskpro.com/gas-masks
The Germans countered with a gas mask (for use by their troops against the possibility of a wind shift blowing their own chemicals back over them) that employed an air filter drum screwed onto the front of the breathing apparatus that could be changed easily and quickly to keep the filtration system fresh during multiple attacks. The British countered with the SBR or Small Box Respirator which became the most widely used gas mask during the war.
The British first built a carbon monoxide respirator that was being used during World War one before the first use of chemical weapons by Germany. Scientists had discovered that unexploded enemy shells gave off extremely high levels of carbon monoxide gas. These levels were found high enough to kill soldiers within 100 meters of unplaced devices in trenches, protection holes and protective areas where carbon monoxide could concentrate further.