Question

how much harmful UV rays are?

Answer 1

UV rays are very harmful for everyone. It's the major reason for skin cancer.It also deactivate photosynthesis.
Hope it helps you.

Answer 2

Hey ,
Here your answer is :-

Ultraviolet rays can also damage the eyes as more than 99 % of ultraviolet radiation is absorbed by the front of the eyes . Corneal damage cataract and macular degeneration are all possible chronic effect of ultraviolet exposure and can ultimately lead to blindness . Melanoma , a type of skin cancer , can also develop within the eyes .
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hope it helps you buddy .