I’ve just spent two weeks cycling in rural France. During that time I don’t recall having a single bogey up my nose, nor for that matter any phlegm. I’ve only been back truck driving a week and everyday I get several hard bogeys up my nose.
My understanding is the nose is the first line of defence in cleaning the air entering the lungs. Given the bogey evidence I put it to you the air in rural France is much cleaner than the air on the highways of the UK