Most people haven’t heard of thirdhand smoke. Researchers said you can't see it. You may not smell it. But if someone smoked inside a home even years ago, the chemicals may still be there.
"When people smoke tobacco or vape, they leave behind a chemical residue," said Georg Matt, director of the Center for Tobacco and the Environment at San Diego State University. "They attach themselves to surfaces, to clothes, to upholstery, to carpets, to walls."
Matt said the residue can remain long after someone moves out.
"If someone has smoked in a home for 5, 10 years and for a generation, tobacco smoke has literally penetrated each and every square inch of that home," he said.
Unlike secondhand smoke, exposure isn't limited to breathing contaminated air.
"Thirdhand smoke exposure can also take place through the skin,” Matt said.
Matt's team analyzed more than 3,000 surface samples to create what they said was the first standardized way to measure how much thirdhand smoke is left behind. The new scale is designed for environmental testing professionals and property managers to assess contamination and determine when cleanup may be needed.
"In one of our studies, we looked at more than 200 apartments in San Diego County, and we could measure tobacco smoke residue in each and every one of them," Matt said.
He added that cleaning alone may not be enough in heavily contaminated homes.
"That chemical residue, just like after a house fire, has penetrated into these receptive surfaces and materials, and there is no washing and cleaning that can get rid of it," he said.
Dr. Anuja Vyas is a pulmonologist at Sharp Healthcare. She’s treated patients who have been affected by thirdhand smoke.
"The best analogy for thirdhand smoke is that it's like glitter," Vyas said. "Once it's out there, it's everywhere."
She said children, older adults and people with asthma, Chronic Obstructive Pulmonary Disease or other lung diseases are among those most vulnerable to its health effects.
"You may notice that if I live with somebody who smokes outside and I'm getting headaches all the time, I'm just not noticing a clear trigger, but it's still something that's there," Vyas said. "The only way you'll see a difference sometimes for our patients is if they move."
The findings come as a new California law requires sellers to disclose thirdhand smoke contamination during residential real estate transactions.
