Answer:
Melanin absorbs dangerous UV rays that can do severe skin damage. But melanin can't absorb all the UV rays, and some people don't have much melanin in their skin.
Step-by-step explanation:
The sun is by far the strongest source of ultraviolet radiation in our environment. Solar emissions include visible light, heat and ultraviolet (UV) radiation. Just as visible light consists of different colours that become apparent in a rainbow, the UV radiation spectrum is divided into three regions called UVA, UVB and UVC. As sunlight passes through the atmosphere, all UVC and most UVB is absorbed by ozone, water vapour, oxygen and carbon dioxide. UVA is not filtered as significantly by the atmosphere.Ozone is a particularly effective absorber of UV radiation. As the ozone layer gets thinner, the protective filter activity of the atmosphere is progressively reduced. Consequently, the people and the environment are exposed to higher levels of UV radiation, especially UVB.
Ozone depletion is caused by human-made chemicals released into the atmosphere and will continue until the use of chlorine and bromine compounds is drastically reduced. International agreements, in particular the Montreal Protocol, are gradually succeeding in phasing out the production of ozone-depleting substances. However, the long life span of the chemicals already released will cause ozone depletion problems to persist for many years to come. A full recovery of the ozone level is not expected until 2050.Most UV-A does reach the surface, but UV-A does little genetic damage to tissues. UV-B is largely responsible for sunburn and skin cancer, though it is mostly absorbed by ozone before reaching the surface. Levels of UV-B radiation at the surface are especially sensitive to the amount of ozone in the stratosphere.