- A new study finds that levels of thirdhand smoke can remain in homes for years at dangerous levels.
- Two of the three compounds in thirdhand smoke can cause cancer and can be ingested by inhaling air and dust and by contact with skin.
- Even in homes with no noticeable smoking odors, contaminants can remain.
Thirdhand smoke is what researchers use to describe what cigarettes leave on surfaces, walls, and furnishings of a home after the smoke clears.
When nicotine in cigarette smoke interacts with nitrous acid, a common molecule in indoor (and outdoor) air, it leaves behind a residue of three compounds, two of which (known by the acronyms NNK and NNN) are known carcinogens.
This trio of tobacco-specific nitrosamines (TSNAs) creates thirdhand smoke and can persist in a home for months or even years, jeopardizing the health of those living there.
Researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have published a new study on thirdhand smoke (THS) that predicts the potential exposure of non-smokers who live in residences where cigarette smoking has taken place.
The researchers found that the amount of these chemicals present in a home where smoking has regularly occurred can exceed California’s safety guidelines.
The study appears in the journal Environmental Science & Technology.
Should we worry about thirdhand smoke?
In California, the Office of Environmental Health Hazard Assessment (OEHHA) established a Prop. 65 No Significant
Risk Levels (NSRLs) of 14 nanograms per day for NNK. Exposure to the long lasting compounds via inhalation, dust ingestion, direct contact, air-to-skin deposition, and epidermal chemistry were all rated by the study to be above California’s NSRL.
Study co-author, Professor Georg Matt of San Diego State University, told Medical News Today:
“We know from other studies that thirdhand smoke can persist for years in homes that have been heavily smoked in. Let me give you an example: We found highly excessive levels of THS in the home of a non-smoker who had lived in this home for more than 20 years, was previously a one-pack-a-day smoker, quit 9 years ago, and had not smoked or allowed smoking in the apartment since.”
The study’s principal investigator, Dr. Hugo Destaillats, Senior Scientist at the Indoor Environment Group in the Energy Analysis and Environmental Impacts Division, spoke with MNT and pointed out some significant findings from a previous study that included more than 200 homes.
“I’m talking magnitudes from a few micrograms per square meter to thousands of micrograms per square meter,”
Dr. Destaillats said brief visits to such homes — or public spaces or restaurants at which smoking was previously allowed — should not be a cause for worry, even if they exceed the NSRL.
“We calculated the daily dose that somebody could be either inhaling or ingesting, or subject to uptake through the skin. These are chronic exposures over long periods of time. We all go to places where a lot of people are smoking. We could have extremely high exposures for short periods of time. If we integrate that over years, that exposure is nothing.”
— Dr. Hugo Destaillats
Thirdhand smoke smell test
“The presence of the smell of stale tobacco smoke is a reliable indicator of thirdhand smoke pollution,” said Prof. Matt. “However, the absence of the smell is not a reliable indicator of the absence of THS,” he stressed.
“This is because not all chemicals found in THS are odorant, and some of the odorant components of THS may have disappeared,” he explained.
Dr. Rachael A. Record, associate professor in the School of Communication at San Diego State University, who was not involved in the study, explained to Medical News Today, “Even in a freshly cleaned space, thirdhand smoke reservoirs can persist, re-emitting toxicants back into the environment.”
Noting that “Real estate agents have tools, and painting is a way to reduce odors temporarily,” Dr. Destaillats quoted a frequently heard comment: “We moved into the house, it smelled fine in the beginning, and now we have some doubts.”
Dr. Destaillats explained this may be because the gypsum powder inside the drywall is “a huge sink for tobacco contaminants.”
Clearing away thirdhand smoke
Dr. Record suggested a few steps people can take to remove or minimize thirdhand smoke from a place.
“The most effective way to protect ourselves from thirdhand smoke is to remove and replace all of the places where thirdhand smoke reservoirs can persist,” he said.
“This includes getting rid of furniture and decorations that were in the room, such as couches and drapes, as well as replacing carpets, drywall, and other materials where the thirdhand smoke can easily stick.”
— Dr. Rachael A. Record
“A more cost-effective solution,” said Dr. Record, “would be to regularly open windows to create a cross-breeze, frequently wash fabrics and wipe surfaces, and regularly vacuum with a HEPA filter. These solutions will not remove the reservoirs, but they will provide some relief.”
“The success of remediation efforts depends on the extent to which the indoor environment is polluted with thirdhand smoke,” said Prof. Matt.
“If you are buying a home where someone has smoked for many years, there is little you can do except gutting and remodeling.” He also endorsed the use of HEPA filters in vacuums and air purifiers.
Dr. Destaillats said cleaning with certain cleaning products might be a good first step: “Another thing people do is painting. Painting, with some products, blocks the contaminants.”
However, Dr. Destaillats noted concerns about a lack of research on the effectiveness of painting for the long-term neutralization of toxins.
Finally, he said, one might consider using an ozone generator, which “are effective, let’s say very short-term, to remove odors. And then the question is, again, the long term.”
Dr. Destaillats said his team is assessing how well ozone generators remove surface contaminants.
“We are not measuring odors. We are measuring concentrations on the surfaces,” Dr. Destaillats said.
Vaping nicotine and e-cigarettes
“Electronic cigarettes are a source of nicotine in the indoor environment,” said Dr. Destaillats. “We have shown that, and other many studies have shown that.”
He said the amount of smoke emitted by electronic cigarettes is lower than traditional cigarettes “for a simple reason, which is that e-cigarettes are activated only when the user puffs, and then, in-between puffs, there are no emissions. Whereas cigarettes emit whether the person puffs or not.”
E-cigarettes are also cleaner in that they put fewer chemicals into the air.
“However, the one chemical that is emitted at the same level is nicotine because that was the whole purpose of e-cigarettes: to substitute the dose of nicotine that people get with a regular cigarette with an electronic cigarette,” Dr. Destaillats added.
Detecting thirdhand smoke in homes
“At the beginning,” recalled Dr. Destaillats, “we [the Berkeley Lab] had a paper back in 2010 that was, I think, very influential, and in a way, initiated this interest in thirdhand smoke. And then after that, there were a number of studies that solidified our understanding.”
“What we are doing now in this paper is incorporating all of that into some simple models to predict what is the potential exposure of non-smokers that live in those environments.”
“So our research group,” Dr. Destaillats continued, “is part of a larger organization that we call the Thirdhand Smoke Consortium. The consortium has been active for almost a decade now. The money for the fund comes directly from sales taxes on cigarettes and electronic cigarettes.”
The consortium uses the funds for research and educational programs. “We have a significant activity in engaging the public, and in translating the research into actionable steps,” he said.
The consortium’s Thirdhand Smoke Resource Center is a comprehensive resource for those wanting to know more about thirdhand smoke in their homes.
Dr. Matt, also a member of the consortium, said, “We are inviting select participants — mostly parents with small children living in California — to participate in a small-scale pilot study using DIY [home-testing] kits.”
Visit the Thirdhand Smoke Resource Center’s FAQ page for more information. The Resource Center also welcomes email inquiries.
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