system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Since the human body is covered in pores, why is acne mostly concentrated on the upper body?

I'm doing some reading of my biology textbook for homework and the current chapter is the integumentary system (skin, hair, nails, etc.) The book says the body is covered in pores, and then goes onto explaining what acne is, how pores get clogged, etc. But it doesn't explain why acne is (for the most part) concentrated on the face, neck, shoulders, back, and chest. Like, I've had one zit on my lower back near my butt and that's it. The rest of it is chest up. I get that if it's hot out and your forehead gets sweaty, obviously some of that sweat will be reabsorbed into the skin and become part of blackheads and whiteheads. But my feet are sweaty in my socks and shoes all day, even when I'm just sitting in class. Shouldn't my feet be covered in zits too? Just struck me as really odd.

I know this isn't NSFW in the sense that it's not about sex or anything, but if I saw one of my classmates reading this, my first thought would be "WTF are you reading?" Figured I'd rather be safe than sorry.

Edit: I don’t understand how this is almost to the point of my root beer comment. I wasn’t looking for awards or updoots, like I was genuinely curious about the concentration on different parts of the body, but thanks I guess haha.
gpt
Sebum is an oil produced by sebaceous glands. You have a concentration of these glands in your face and on your head. If they produce a little too much oil, your pores get clogged with oil/dead skin cells and you get acne.  So, you can get a clogged pore anywhere but it happens more often where you have more sebaceous glands due to oily buildup.