A method to survey the microbes in peoples respiratory tract would be useful for this.

It would be a delicate balance, but possibly aerosoled form of say particular pollens would give a base for certain advantageous microbes to flourish. They could provide innate immunity to some aliments.
-- lostmind, Dec 27 2011

If it has something to do with microbes, it's probably that there are simply less airborne ones that affect humans in the country.
-- rcarty, Dec 27 2011



random, halfbakery