You already knew that smoking isn't good for you.

It's been said for a long time that "second-hand" smoke isn't healthy either.

Now, some scientists say, there's evidence that "third-hand" smoke — the residue that clings to furniture, carpets, walls and other surfaces — puts toxins in the air as well.

Talk of the Nation's Science Friday explored the topic last week:

And today, the Proceedings of the National Academy Sciences released a study on the subject with findings that "raise concerns about exposures."

Our colleague Scott Hensley blogs about such subjects at Shots.