Photobleaching Construction Paper with Fluorescent Lights

I took down an old Bradley University Chemistry Club bulletin board and was impressed how, over the course of years, light from the fluorescent lights in the hallway in Olin Hall had penetrated thin copy paper (upper sheet in picture) and bleached the underlying construction paper from blue to gray (lower sheet in picture).  I was also impressed how ink on the paper had slowed that process sufficiently that the printed ink on the copy paper left an image on the construction paper.