Narrator:        This is Science Today. If you've ever been in a house or a car that belongs to a smoker, you're familiar with the acrid, lingering scent of tobacco. What you may not know is that the residue from cigarette smoke remains in the fabrics and surfaces in indoor environments. It's called thirdhand smoke and its potential health risks are just now being studied.  Physical chemist Lara Gundel of the Lawrence Berkeley National Laboratory is looking into its effects.

Gundel:          It turned out nicotine stuck to the walls. Not only that, nicotine would be sucked up into materials like wall board that we use commonly in this country and it would be really hard to get it out, but it would diffuse out along with other compounds in the smoke.

Narrator:        Gundel says exposure may also include inhaling dust that contains residues from thirdhand smoke.

Gundel:          Ordinary house dust that our vacuums pick up can pick up thirdhand smoke from the air. So, that means the people most at risk of exposure are children. They tend to have more surface contact indoors because they crawl around on carpets.

Narrator:        For Science Today, I'm Larissa Branin.