This is a 1939 Avon Gas Mask from our war and weaponry collection.
During World War I (1914-1918) many soldiers had been badly injured, or killed, when their enemies threw bombs at them which released poisonous fumes when they exploded. During World War II, Britain was very worried that these gas bombs would be dropped on the country during air raids and injure innocent civilians. So the authorities supplied everyone with gas masks so that they would be protected if this happened.
It was the responsibility of air raid wardens to ensure that everybody had been issued with a gas mask.
The gas masks had a filter near the mouth which prevented the gas from coming inside. The masks covered your whole face so your eyes were also protected.
Fortunately the gas masks were never used as no gas bombs were dropped in Britain during World War II.