With no controls on the emissions of its armada of diesel-engined vehicles, Calcutta is cursed with heavy atmospheric pollution - as any visitor to the city soon learns. For its residents, lung problems are part of everyday life. Rush hours are especially noxious, with grey fumes frequently obscuring the sunset. During the long months when the city holds its breath and waits for the monsoons to hit, the still and heavy air can be unbearable; and when the rains finally roll in at the end of June, Calcutta becomes a swamp. Being obliged to wade thigh-deep through filthy water, along roads riddled with pot-holes and open manholes, contributes to further health problems. Calcutta's water table is contaminated to a depth of over 6m, and gastric disease is endemic. Anyone who can afford it equips their home with its own purification systems or tube well. On top of all that, the Calcutta Corporation is hopelessly unequal to the task of keeping the city clean; streets are strewn with litter and rubbish tips pile shoulder high.