Why are museums concerned about controlling... Art question?

Question

Why are museums concerned about controlling the humidity, temperature and light inside their buildings?

Answer 1

To protect the art. Light, humidity and heat damages and dries out old pigments and canvases. Go in the Degas pastels room at the Met in NYC - it is almost pitch black because the drawings are so fragile. Pax-C

Answer 2

Because any number of those things can ruin an old piece of art if you're not careful. They are trying to preserve the art for as long as they can.

Answer 3

It is for preservation. Some of the more fragile pieces of art can even be stored in cases where they are surrounded by nitrogen rather than a normal mixture of air. Some displays of older photographs will be shown in dimmed galleries with clothes the viewer has to lift up; all to reduced the amount of light the photographs are exposed to over time.