5 Things to Know About Sunscreen by the Window

UVB rays that cause sunburn are blocked by glass, but UVA rays that cause aging and skin cancer pass straight through. You won’t burn, but your skin is still getting damaged.

If you sit within arm’s reach of a window for hours—working from home, at a coffee shop, or in a reading chair—treat it like being outside without the burn risk. A lightweight moisturizer with SPF 30 is enough.

Car windows offer the same risk. Drivers who age more on one side of their face than the other are proof that UVA rays penetrate glass.

Your skin does not know you are inside. The window is not a force field against all UV damage.

You only need sunscreen by the window if you are near it for more than a few minutes daily. Brief exposure is not a concern.