Where were gas masks used?

In Great Britain, the government announced in mid - 1936 that it would manufacture sufficient gas masks for the whole population. By the time they were issued in 1939 some 37 million gas masks had been produced and stockpiled. Once issued, it was compulsory to always carry you gas mask and in the early stages of the war failure to carry it led to prosecution. However, the various types of holders and bags for the masks quickly proved useful for carrying other items such as ladies cosmetics and make-up and even Sandwiches. As the war progressed the law regarding carrying the mask was enforced less rigorously. - I Warner