Can you get sunburned through a window?
Almost never. Ordinary glass blocks nearly all UVB — the wavelength that causes sunburn (and vitamin D synthesis). But standard glass lets through a large share ofUVA, which penetrates deeper and drives skin aging, pigmentation, and long-term damage. So: no burn through the window, but not "no harm" either.
Where it actually matters
- Cars. Windshields are laminated and block both UVB and most UVA — butside windows are ordinary tempered glass and often pass 50%+ of UVA. Studies of long-haul drivers show measurably more photoaging and skin cancers on the window-side arm and face. On long drives with high UV, that arm deserves sunscreen or a sleeve.
- Sunny desks and window seats. Hours beside a bright window add up in UVA terms — worth knowing for daily-basis exposure, irrelevant for an occasional afternoon.
- Planes. At cruise altitude UV is far stronger and windows pass some UVA; pilots show elevated melanoma rates. Passengers on occasional flights needn't worry.
- Vitamin D: since UVB is blocked, you make none through glass — a sunny window seat does not count toward your vitamin D window.