Capt. W. D. Smith of Greenville, S.C., Camp Blanding Chemical Warfare Service officer, trains in the use of the gas mask in Camp Blanding, Florida on August 19, 1942. Just to be sure that his office force could work under any conditions, he issued instructions that for an hour each day all work be done in gas masks to prove that conversations, even on the telephone and in dictation, could be carried on and other work done efficiently. (Photo by AP Photo)





Two women wearing flu masks during the flu epidemic which followed the First World War, 1929. (Photo by Keystone/Getty Images)





This gas-masked nurse is pushing a baby carriage, although it looks like a field kitchen, there's a baby in it, in London, on December 22, 1938. Its inventor, E.W. Mills of Huxtable, Kent, England, says it is gas-proof, it works on the same principle as the mask worn by the nurse. Mills thought it up during the war scare. (Photo by AP Photo)





A patient wearing a flu mask during the flu epidemic which followed the First World War, 1919. (Photo by Topical Press Agency/Getty Images)





The children proceed with their lesson in writing, all are wearing their gas masks which does not seem to embarrass them in the least in England on July 1, 1941. The main object is to keep their minds constantly occupied, so they forget all about the masks. (Photo by Laurence Harris/AP Photo)





Navy, Army and Air Force are combining in coastal defense exercises which continued over a wide area of sea and land between Portsmouth and Plymouth, Devon. Among the innovations used, when an air raid black-out plunged Portsmouth into darkness was this new type of anti gas decontamination suit. It is absolutely air tight, and cannot be worn for more than 40 minutes. Ground engineers at an Air Force station near Portsmouth, Hampshire, on July 15, 1937, wearing the new decontamination suits in readiness for a raid. (Photo by AP Photo)





Dancers at the Windmill Theatre in London, practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)





This experiment was recently conducted to illustrate the new non-breakable glass which is being fitted into gas masks, October 19, 1932 in Germany. Sale of these masks is common in the markets of Berlin, and many of them sold for domestic animals. They are produced to fit tightly, and gas lessons are given in many places. (Photo by AP Photo)





An American policeman wearing a “Flu Mask” to protect himself from the outbreak of Spanish flu following World War I, 1918. (Photo by Topical Press Agency/Getty Images)





A teacher instructs his class in the correct gas mask drill in a school in Yorkshire, England, on September 15, 1939. (Photo by AP Photo)





Margaret Klein, left, and Mrs. Marvin Blumenfeld sacrificed glamour for expedience as they passed out a health bulletin,“A woman's view of air pollution”, in front of Kiel Auditorium in St. Louis, September 27, 1966. Inside, members of the East-West Coordinating Council were holding a hearing on air pollution in the metropolitan area. (Photo by AP Photo)