Interesting; could that be caused by most cities being near sea level and most people living near cities, and thus pollution rather than oxygen might be the root cause?
I don't have a link to the study, but the researchers of the study I read were very meticulous and did discard all other obvious explanations before concluding that altitude was the best explanation.
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Interesting; could that be caused by most cities being near sea level and most people living near cities, and thus pollution rather than oxygen might be the root cause?
I don't have a link to the study, but the researchers of the study I read were very meticulous and did discard all other obvious explanations before concluding that altitude was the best explanation.