Sidmouth has several hot spots where the air pollution, including CO2, is quite high: “Significant air pollution” in Sidmouth – update – Vision Group for Sidmouth
You can get “a free Air Quality report for your address” here: addresspollution.org
There are some excellent maps available – with an interactive map of greenhouse gas emissions: Local Authority GHG Map
And a general emission map where you can chose the pollutant: UK Emissions Interactive Map
What can we do about it? How to tackle air pollution – Vision Group for Sidmouth
[Information also available on the CAPS website: CAPS – Climate Awareness Partnership Sidmouth