[Sun Care] Does this really mean we need to wear sunscreen indoors in every season?

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We know UVA penetrates from windows and I always see this truck driver's picture shown as evidence for why. I'm not convinced if this really means we need to wear sunscreen indoors every day though. This is why I hesitate.The left side of the truck driver's face is only a hand-size away from the window, even most of us who sit near windows at home or at work still have more space between our face and the window.There is no curtain in the truck.My question is this. I work from home and sit on the same couch every day that is about 7-9 hand spans away from the window. There's a net curtain that is always closed. I still wear sunscreen indoors in summer, but I wonder if I really need it on cloudy fall/winter days when I'll be at home all day. The main reason I hesitate is Vitamin D. I would prefer to get Vitamin D naturally and not with a supplement. I already spend most of my time indoors, I feel like if I also wear sunscreen on cloudy days indoors this might lead to Vitamin D deficiency, although I'm very fair skinned and need less exposure to the sun for Vit D.What do you think I should do? What is your sunscreen habit about indoors?
Girls Blog 2015
Submitted by Redhaired103