Ultraviolet radiation can be separated in three bands, depending on the wave frequency: Ultraviolet A, B and C (UVA, UVB and UVC). Each band inflicts a different effect over living organisms. UVA is mostly harmless, and is reflected by proteins, not abosrbed by the organism. UVB can damage the DNA, so animals, for example, produce melanin, which reflects the UVB, so it wonīt cause any harm. UVC is more rare, but is more powerful. DNA absorbs directly UVC, which causes a serious havoc over the mollecular interactions between nucleotids, causing either the death of the damaged cell, or mutations that can cause cancer.
The aproximated proportion between the 3 bands that hit our planet is 50% UVA, 48% UVB and 2% UVC. Donīt be paranoid about UVC hitting Earth all the time, because our cells have a very efficient DNA repairing system, that can prevent us from having any problems, if we take the correct precautions.
Ultraviolet rays of the 3 bands come naturally from the sun. So, avoid staying outside without protection when the sun is stronger, between 11am and 3pm. If you have to garden on those times, use protection for your skin, even if itīs cloudy, or the weather is cold.