Fog everywhere. Fog up the river... fog down the river, where it rolls defiled among the tiers of shipping, and the waterside pollutions of a great (and dirty) city... Fog lying out on the yards, and hoevering in the rigging of greta ships; fog dropping on the gunwales of barges and small boats. Fog in the eyes and throats of ancient Greenwich pensioners, wheezing by the firesides... Chance people on the bridges peeping over the parapets into a nether sky of fog, with fog all around them, as if they were up in a balloon and hanging in the misty clouds. - Charles Dickens, Bleak House. What major cause of the conditions described in the Passage