system
Given the following post, respond as if you're commenting on Reddit:
human
Is mountain air really the healthiest/least polluted air?

Is there less polution in the mountains (for example the Alps in France) than in some desolate village at sea-level?
gpt
It's not so much the altitude as it is proximity to large cities and prevailing wind patterns.  There aren't a lot of large cities with manufacturing and chemical processing plants near the French Alps, for example, and the higher you go, the smaller the population is - therefore, the air is much cleaner.  

In Hawaii, some of "most pure" air in the world is blown in from the Pacific, because although these winds originate in China, they travel over the pacific for approximately 3 weeks before making landfall in Hawaii which allows all the pollution to settle out.