I recall reading a couple of articles on this subject about cities in general [1, 2]. London was called out as OK: "Our model indicates that in London health b

I recall reading a couple of articles on this subject about cities in general [1, 2]. London was called out as OK: "Our model indicates that in London health benefits of active travel always outweigh the risk from pollution. [1]" What I'd like to know is, given an accident rate, pollution level, and other factors, what is the "safety factor" of walking/cycling vs. tube/rail/bus/car/taxi? Edit: These graphs are great: https://ig.ft.com/sites/urban-cycling/assets/pollution-london-large.png https://ig.ft.com/sites/urban-cycling/assets/pollution-londo... https://ig.ft.com/sites/urban-cycling/assets/pollution-world-large.png https://ig.ft.com/sites/urban-cycling/assets/pollution-world... Interesting stats: - In 1% of cities worldwide, pollution levels are high enough that "active travel" is dangerous past 30mins of activity. - ~40,000 people in the UK die earlier every year due to air pollution. 1: http://www.cam.ac.uk/research/news/walking-and-cycling-good-for-health-even-in-cities-with-higher-levels-of-air-pollution http://www.cam.ac.uk/research/news/walking-and-cycling-good-... 2: https://ig.ft.com/sites/urban-cycling/ https://ig.ft.com/sites/urban-cycling/