Why do umbrellas protect against UV rays?

Sun umbrella
The sun umbrella can block about 70 percent of ultraviolet light, but it cannot block the reflected ultraviolet light. If there is no anti-ultraviolet coating umbrella, you can also use ordinary sun umbrella, black umbrella defense effect is relatively good, followed by pink, yellow, and red almost no anti-ultraviolet function.
What are the size of the sun umbrella
The size of the umbrella is generally 48 inches, 52 inches, 54 inches, 56 inches, 60 inches and so on. 48 inches of which are regular size. The 48-inch sun umbrella can open 2.4 meters, and we choose the sun umbrella to determine the size of the sun according to our actual needs.