] All the same, the London of JA's period was nearly as nasty as in Dickens's time: it hadn't got so large, but there were still lots of coal fires, horses and industries.

There were local pockets in Jane Austen's time that were seriously polluted, but these areas wasn't anything like on the same scale and density as the polluted areas of the high Victorian period. (The construction of truly large-scale factories was only just beginning, for one thing.)

As I've said before, there was plenty of squalor in Jane Austen's day, but it was mostly old inherited rural squalor that hadn't changed all that much since the middle ages -- it was during the remainder of the 19th century after Jane Austen's death when the population of England increased about threefold, and mass urban slum squalor came to be characteristic. The first prominint event marking the transition was the Great London Cholera Epidemic of 1831 (14 years after Jane Austen's death).