I've been trying to understand a little bit more on UV rays (and sun screen) and the good and bad of sun exposure. Anyone has any good materials to read about this ?

From the little i get, only 3% of sunlight is UV ray, and out of that 95% is UVA, 5% is UVB (UVC is blocked by the ozone)

cons of UVB - Excessive UVB is harmful and can cause skin cancer

pros of UVB - Stimulates Vitamin D3 production, increases seratonin (your happy drug), improves many skin condition and in fact UVB is reproduced as solar radiation (heliotherapy) or artificial UV radiation (phototherapy) to fix skin problems, produces melanin which protects the skin.

all sunscreen blocks UVB, and some blocks both

As for UVA, not too harmful apparently, but too much can cause collagen damage and premature aging. UV rays can also help reduce blood pressure, heart problems and kill bacteria.

This curiosity came abt as I was reading on sunscreens and wondering if there is more harm than good.

There are a lot more articles out there on how bad the sun is compared to the good of it. If you have more info on the good and bad of sun (and sunscreens), would love the input!