I know when I used to drive for a living my left arm would tan and burn.
Is it possible to absorb vitamin D, tan or sunburn when sitting near a window?
If the window was manufactured with low-e glass, the UV light will be blocked and no vitimin d will be absorbed. Many windows are made with low-e glass or they are coated to prevent UV light, which fades furniture, carpet, etc.
I have..... Sunburned..... Pfft. Lol!
Depends upon the window. Many have UV blockers designed to keep certain spectrum of light from heating up your house, and also protects against fading materials inside.
I imagine, the cheaper the window the less they block.