On a sunny day, relaxing indoors by the window might spark curiosity: Can you still get a tan?
Answer: Yes, if you stay long enough. Sunlight's radiation spans wavelengths from 100 to 4000 ångströms. Tanning primarily comes from UV rays between 2900 and 3050 ångströms.
Are you protected behind glass?
Ordinary window glass blocks rays below 3000 ångströms, providing substantial but not complete protection. You can still tan or burn over time.
* An ångström is 1/10 of a billionth of a meter (0.1 nanometers).
