We're all aware of the old canary down a coalmine story. Miners would drop tools and flee if their caged canaries fell from their perch as it indicated the presence of poisonous gas.

Well, there is now a European study underway to establish if the decline of our common house sparrow, down 68 % between 1994 and 2009 (BTO Breeding Bird Survey data), is in any way linked with air pollution.

We know that a lack of food…