The British first built a carbon monoxide respirator that was in use during World War One before the first use of chemical weapons by the Germans. Scientists had discovered that unexploded enemy shells gave off extremely high levels of carbon monoxide gas. These levels were found to be high enough to kill soldiers within 100 yards of the unexploded devices in trenches, foxholes and other small, sheltered protective areas where the carbon monoxide could concentrate even further. The effect was similar to a car exhaust when an automobile is left running in a closed garage.

It was a Canadian who designed a “smoke helmet” with a single exhaling tube filled with chemical solvents to neutralize the chlorine used in the gas attacks. Using this design, the smoke helmet was adapted by the allied forces and is widely considered to be the first mass produced gas mask employed for use against the Germans. 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.