Why do I get sunburned through a window?

Know your glass: windshield = laminated (good UVA block); side windows = usually tempered (weaker).
SPF the driving side: long bright commutes earn sunscreen on the window-side arm and face.
Consider UV film: it upgrades any window to near-total UV block.
Get seen if: you notice one-sided sun spots, freckling, or rough patches - asymmetric sun damage deserves a skin check.

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Because glass filters sunlight unevenly - it stops most of the burning rays but waves the aging ones through. The physics from the photoprotection literature: all commercial and car glass blocks the majority of UVB (the main burn-and-tan wavelength), but UVA transmission depends on the glass type - and UVA penetrates deeper, drives photoaging and pigment changes, and contributes to skin cancer. Car windows are the classic trap: windshields are laminated and block UVA well, but side and rear windows are usually tempered glass, which lets much more UVA through - the review of window photoprotection notes laminated glass offers better UVA protection than tempered. That is why professional drivers and long commuters accumulate one-sided sun damage, and why you can pink up on a long bright drive with the windows up. The fixes: sunscreen on the driving side for long bright trips, UV-filtering window film (it upgrades any glass to near-total block), and do not trust shade-feel - glass that blocks heat glare still passes UVA. Home and office windows count too if you sit in direct sun for hours daily.

Why do I get sunburned through a window?

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