Every once in a while I come across something that says you shouldn’t recycle pizza boxes, but they never said why. I thought that it was because some pizza boxes might be coated with non-stick chemicals that would prohibit recycling. Since the place I get my pizza from uses a piece of wax paper, I figured the recycling was fine.
It turns out the problem is actually with grease that can drip off the pizza and onto the box. When the box is recycled the grease can ruin the whole batch of paper. So while you thought you were helping out the planet by recycling your pizza box, you really just ruined a huge batch of otherwise recyclable paper. Good going! That should make you feel guilty for a while.
This is the same reason you should not put things like paper napkins and plates in the recycling bin.
Read “The Pizza Box Mystery” on Earth911 for a deeper explanation on this topic.