I agree with some points you make- but there is no such thing as a free pollution country. The earth shares the same global wind patterns so no country is "pollution free". The wind patterns bring particles from one country to another. An easy example (or more easy visualized one) Is volcanic ash. When a volcano erupts, the particles are thrown in the atmosphere and moved by the wind. This happened 2 years ago or so when a Icelandic volcano erupted- the ash moved all the way to the UK- altering aviation and more. What you could say is countries that dont emit harsh pollutants most likely are free of "hotspots" usual found in big cities and high industry countries.

al13: Interesting post but it's ultimately just your opinion, which I disagree with. If you believe that acne is caused by modern civilization, how do you explain the fact that "acne" is an Ancient Greek word meaning "eruption on (or of) the face?" Please see links like this one to read a brief summary of age-old acne documentation: http://adultacnetreatmentreviews.com/acne-articles/history-of-acne

But you can research for yourself! Or just believe what you want. I do agree that diet is a BIG factor in the development of acne in Western civilization too. Exactly what in our diets causes acne? Well, I think the answer to that question depends on the person. Different people are affected in different ways and some people are more predisposed to suffering from the "disease." And, of course, don't forget the fact that the world's population is much larger and more diverse now than it was in the past. So, in the past, civilizations in which acne was present were much smaller, perhaps more closed-off, and more "local" than modern cities currently.

So, why do some people have the "acne gene" (if in fact something like that does exist, which I don't know) and why do others not have it? Look to your family tree. Your answers are in there somewhere!