Earthquakes and global warming
Ultraviolet radiation is found naturally in sunlight. Exposure to ultraviolet radiation can cause:
We cannot see or feel ultraviolet radiation, but our skin responds to it by turning darker. This happens in an attempt to reduce the amount of ultraviolet radiation that reaches deeper skin tissues.
Darker skins absorb more ultraviolet light, so less ultraviolet radiation reaches the deeper tissues. This is important because ultraviolet radiation can cause normal cells to become cancerous.
Sunblocks can reduce the damage caused by ultraviolet radiation. They contain chemicals that absorb a lot of the radiation and prevent it from reaching our skin. They may also contain chemicals that reflect some of the radiation away from the skin.
Manufacturers of sunblocks make products with different sun protection factors:
If, for example, you would get sunburnt after ten minutes in the sun, with Factor 5 applied you could stay in the sun for 50 minutes - or for 1500 minutes with Factor 150 applied. But the real time is usually lower, because some of the sunblock gets absorbed by the skin, and some gets rubbed off.
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