The map of pollution shows that there are higher levels of air pollution on the Great Wester railway line than on the M4 heading out of London. It also shows that although pollution levels on the M25 are very high, they aren't as high as Park Lane, Euston Road, or Catford town centre.
The geographic impact of planes on air pollution will depend on their altitude and the wind patterns. Generally speaking, the higher the planes the less close by or concentrated the pollution levels. So the Biggin Hill stack for Heathrow airport shows some of the lowest levels of air pollution in London.
The contribution of air traffic to air pollution appears to be relatively small compared to road traffic.