Saas-Fee - What sun factor is advisable?
At altitude the suns rays are extremely powerful even if it doesn't feel hot. You have to be especially careful when in the snow because it reflects extra ultraviolet radiation onto your skin. It is deceiving when it is cloudy and even snowing, as even then you can get burnt!
A high factor is advisable. Perhaps SPF 20+. Try to go for the better products such as Sunsense, Ambre Solaire or Piz Bruin. You need to check that the cream has a UVA and UVB rating. To learn more about sunscreens visit
www.dermnetnz.org/treatments/sunscreens.html