Knowing where air pollution is particularly high can help you to avoid it - taking two extra minutes to take a smaller road can cut your exposure drastically.
walkit.com can provide a low pollution route for most areas of London.
Knowing when air pollution is particularly high can help you know when these decisions will make the most difference.
www.londonair.org.uk can tell you past, current and predicted levels, and where legal limits are being exceeded.
airTEXT provides forecasts of air quality for the next 48 hrs for Greater London