Gas Tests On The Tube
Tests will be carried out on the London Underground this month to see how quickly poisonous gas spreads throughout the tube network.
The trials will see non hazardous gas pumped into 11 stations including Pimlico, Westminster, Oxford Circus and Leicester Square.
Its to check protocols and response times in the event of dangerous gases being released, either deliberately or accidentally.
The test is being carried out by the Department of Transport.