School - how harmful is the sun rays?

Human skin has special cells, melanocytes. These cells provide natural, built-in sun protection. You can see it in action each time you tan. Melanocytes produce dark brown substance, called melanin, which does not allow sun rays to penetrate deep into the skin layers as it would be damaging. At the same time sun light stimulates cell generation, skin becomes thicker, and therefore more resistant to UV rays. Turns out the sun is actually good for the skin.

Well . . . People with fair skin don't have enough melanin producing cells, their sun protection mechanism is not strong, and these people get sun burns pretty quickly. UV rays have a very strong biological effect, they can damage protein molecules and even alter genetic material causing healthy cells to become malignant. So tanning is bad.

Could say so, but . . . Sun energy is good for health. Increased blood flow to the skin stimulates cell regeneration, helps to fight acne, smooth scars and minor skin imperfections. Sun light is a necessary factor for Vitamin D production. Sun stimulates immune system and makes us feel happier and healthier.