UV rays and Clouds and Plastic?

Question

Is it true that there are less UV rays reaching ground level on a cloudy day? i.e do clouds block UV?

Also how much UV light do most generic plastics filter? 50%, 80% 100% ...?

Answer 1

As I know,

Yes, you do get a UV exposure on a cloudy day, UV type of B still reaching it, even tho u dont get burned by UV type A.

Generic plastics filter blocks almost 100%.

Answer 2

Clouds play a big role in the amount of UV radiation reaching the ground. On a cloudy day, depending on the shape and thickness of the clouds, they can absorb and reflect 35-85% of the sun’s radiant energy, and along with the other effects prevent all but a negligible amount of radiation from reaching the ground. Many reptiles seek the security of their burrows or hiding places during rain, stormy and overcast conditions

Generic plastics filter 99%