The concept of a protective mask against chemical assault dates back over 500 decades, to Leonardo da Vinci (Smart, 1997). From the mid-nineteenth century, protective masks were proposed in the United States and Europe for both military and industrial use.
The modern gas mask was developed by the Germans with sodium thiosulfate- and bicarbonate-soaked pads, and it was used during World War I (Joy, 1997). The English and French soon followed with their own variations of gas masks (Joy, 1997). You can check out this link to find different types of gas mask available today.
In 1916, the Germans introduced a mask that incorporated a canister through which the soldiers breathed (Joy, 1997). Initially, the American forces in World War I utilized gas masks obtained from allies fighting in the war (Smart, 1997). In 1918, the Americans introduced Richardson, Flory, and Kops (RFK) mask, a modified variant of the British mask.
Moreover, masks were developed for the animals, such as horses, that supported the war efforts. Decontamination efforts during World War I were rudimentary and included chemical neutralization and aeration of clothes and gear. Even though the need to find chemical agents was clearly identified, hardly any progress was made during World War I.