Do You Need Sunscreen Indoors in Winter? (The Window Answer)
Your desk-by-the-window setup has a UVA problem.
Standard window glass blocks most UVB but transmits much of the longer-wavelength UVA, which makes up roughly 95% of the UV reaching us and drives aging.
Dermatologists note that ordinary glass stops sunburn-causing UVB but lets aging UVA through, so a desk beside a sunny window delivers a slow, cumulative dose even in winter.
Questions we get a lot
Does UV really come through windows?
Yes for UVA. Standard glass blocks most UVB but lets UVA through, so windows at home, in the office, or a car's side windows still expose skin to deeper, aging rays (laminated windshields block most UVA). If you sit near a sunny window for hours, that exposure adds up.
Do I need sunscreen indoors in winter?
If you spend long stretches beside a window in daylight, a daily broad-spectrum sunscreen is sensible because UVA passes through glass year-round and its effects are cumulative. If you are away from windows in a typical room, the indoor UV dose is low and sunscreen is optional.
r/30PlusSkinCare: 'Do I need sunscreen if I sit by a window all day in winter?'