Experts Warn Of Danger From 'Third-Hand Smoke'

(CBS) -- You've heard of second-hand smoke and the dangers non-smokers face from it. But, now, there's a new threat, from something called third-hand smoke.

CBS 2's Mary Kay Kleist tells us what it is and where we might encounter it.

You can smell it, but you can't see it. Someone's hair. an empty elevator; the strong scent of cigarettes when no cigarette is in sight.

Many people have no idea that third-hand smoke, the toxic brew of gases and particles, lingers in carpets, sofas and clothes for months after a cigarette is put out. The residue includes heavy metals, carcinogens and even radioactive materials that young children can ingest, as they play on the floor.

Chemist Lara Gundel collects fallout from smoke to see how it interacts with other materials.

"What we have found is that residues of tobacco smoke will get more toxic with time," as nicotine is inhaled into the lungs as dust, Gundel said. "Those particles are teeny particles and they're very irritating. They're more irritating than nicotine or cigarette particles themselves."

San Diego State University psychology professor Georg Matt was the lead researcher in a study on the effects of third-hand smoek.

"We find these compounds in some apartments, six months, maybe even a year or longer," Matt said.

In his study, Matt tested apartments after smokers moved out and non-smoking families moved in.

The apartments were cleaned and painted, yet he found nicotine all over, including on the hands of non-smoking adults and in the urine of children.

"This child, as well as the adults, are likely to get exposed to tobacco smoke that was smoked in that apartment months ago," Matt said.

Scientists said that children's exposure to third-hand smoke can be 10 times greater than adults', because of their small size and their tendency to put things in their mouths.

"You can't just open the window and it goes away. These are daily exposures. These are daily contact. When you live in an environment like this, you cannot escape it," Matt said.

The Surgeon General says that there is no safe level of tobacco toxic exposure. There are thousands of chemicals in tobacco smoke. They say the only way to fully protect your children, and non-smoking adults in your family, is to make your home and car smoke-free.