Gas mask
From Tardis Wiki, the free Doctor Who reference
Gas masks were devices invented in World War I to enable Humans to resist the effects of poison gas. In 1941 the plague caused by the Chula nanogenes, meant that anyone infected grew a gas mask for a face. (DW: The Empty Child/The Doctor Dances) In 2009 gas masks were used by UNIT during the Sontaran attack on Earth. (DW: The Poison Sky)
