Good point. It was too hot last week as well, though.
The air quality in London has vastly improved since the 1980s and 90s - I used to walk 20 minutes to work and by the time I got there, a tissue wiped across my face was black with soot and dirt (something that the congestion zone, LPG/electric buses and low emissions zones has dramatically changed in recent years). You're still dirty after a day, but at least it's not twenty minutes washing, then cleansing, then deeper cleansing, then toner and the cotton wool is still coming up black, so you end up starting again. It's been so bad for two centuries that the dominant type of Poplar Moth are/were almost black, rather than light grey, as the paler type were selected against by being more easily seen and eaten by birds.
On my first stay in Devon, my hair was a good shade lighter, my skin was better and I felt properly clean and fresh - part of this was soft water, but part was that dirt and soot wasn't immediately clinging on my face again. Because the air was clean.
However, the tube is still revolting and it's possible to get bedbugs and headlice hitching a ride on you from it, along with flea bites. Many companies in London changed from installing contract carpet and carpet tiles when hard floors became more fashionable because they had been spending far too much money on defleaing carpets - if you had to kneel down to file things in the bottom drawers of cabinets (because most things were still held on paper in the 90s), you'd frequently get a pin prick feeling in your knees. That wasn't the carpet texture, it was fleas - and they had to come from somewhere, most likely place being off people who used public transport to get there.