‘When the Central Line opened in 1900, it introduced hanging straps and proper windows, but drew renewed complaints of bad air. A bureaucrat in the Sudan Political Service said that it smelled like crocodile’s breath. The Central Railway retorted: ‘It has been practically demonstrated by physiological and chemical experiments that a live man might be sealed up in a lead coffin for half an hour without any resultant feeling of oppression – I say nothing of depression – provided he were treated as frozen mutton in a cold store, so that the air he breathed might still remain cold.’ Not until the 1930s was the atmosphere of the Tube made palatable by means of blowing filtered, ozonised air into it from the outside world.’
From James Meek’s LRB essay on the Tube, “Crocodile’s Breath.”