Japanese instructions for the use of gas masks. Part of a civil defense booklet issued after the Doolittle Raid, these instructions covered the use of the Model 99 gas mask (top), the most common civilian-issued model. The bottom row shows the operation of the 16th Year, Model A gas mask. Early versions were made of tan canvas and later versions of olive drab rubber. Thousands of gas masks were issued to civilians, not only in case the Americans used chemical weapons, but for breathing during firefighting.