Do I need sunscreen indoors?
Last updated September 3, 2026.
Mostly no - away from windows, indoor sunscreen adds little: lighting emits negligible UV and glass blocks the burning UVB. The exception dermatologists care about: hours of daily direct sun through glass, because UVA - the photoaging wavelength - passes through ordinary windows. A desk against a bright window for years is a real cumulative dose. Decision rule: sunny window seat most days = broad-spectrum SPF 30 in the morning; interior rooms = optional. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What to do
- Judge by the window: hours of direct glass-filtered sun daily = yes; interior rooms = optional.
- Use broad-spectrum SPF 30: UVA protection is the point indoors.
- Count the in-between exposure: walks, drives, and lunch breaks still count as sun.
- Get seen if: years of a sunny desk have left new spots or uneven pigment - a dermatologist can sort damage from normal aging.
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