We do not recommend using this face shield as a form of protection from the sun. The shield was designed for protection from riding environments on the road (bugs, stones, etc). I would still invest in high quality riding glasses/googles with SPF for the eyes and high SPF sunscreen for the skin. The shield will help with additional blockage, but it was not designed for the level of protection you are looking for. The smoke colorway is for tinting not sun protection in this particular style.
A better alternative would be PN 98394-11VW. This ¾ Helmet with Retractable Sun Shield has a face shield that features 95% UV protection.