On 10 May 1915 Canadian physician Cluny Macpherson first presented his gas mask invention to the British War Office.

Cluny Macpherson (18 March 1879 – 16 November 1966) in the First World War was  a captain and Principal Medical Officer of the new 1st Newfoundland Regiment. The German army used poison gas for the first time against Allied troops at the Second Battle of Ypres, Belgium on April 22, 1915.

Cotton wool wrapped in muslin was issued to the troops by 1 May and followed by the Black Veil Respirator, a cotton pad soaked in an absorbent solution which was secured over the mouth using black cotton veiling.

Cluny Macpherson sought to improve on this and came up with a mask made of chemical absorbing fabric and which fitted over the head. A 50.5 cm × 48 cm (19.9 in × 18.9 in) canvas hood treated with chlorine-absorbing chemicals, and fitted with a transparent mica eyepiece. Macpherson presented his idea to the War Office Anti-Gas Department on May 10, 1915, with prototypes being developed soon after. The design was adopted by the British Army and introduced as the British Smoke Hood in June 1915.

To read more about Cluny Macpherson click on this link : Dr. Cluny Macpherson