It's well known that smoking can have a serious effect on your health. It's also known that inhaling someone else's second hand smoke is bad for you too, but now a new report suggests third-hand smoke can also pose a health risk.
A US study led by researchers from the Lawrence Berkeley National Laboratory, has found that third-hand smoke - tobacco residue clinging to surfaces is also bad for you. The study is the first to quantify the reactions of third-hand smoke with nitrous acid.
The study, which was published in the Proceedings of the National Academy of Sciences (PNAS) found that when a cigarette burns, nicotine is released in the form of a vapor that collects and condenses on indoor surfaces such as walls, carpeting, drapes and furniture, where it can linger for months. Researchers discovered tobacco smoke residues found on everyday surfaces react with molecules in indoor air to form potent cancer causing chemicals.
"Our study shows that when this residual nicotine reacts with ambient nitrous acid it forms carcinogenic tobacco-specific nitrosamines, or TSNAs," said Hugo Destaillats, a corresponding author of the study.
Exposure
The most likely human exposure to TSNAs is through either inhalation of dust or the contact of skin with carpet or clothes - making third-hand smoke particularly dangerous to infants and toddlers.
They found that opening a window or turning on a fan to air out a room while a cigarette burns does not eliminate the hazard of third-hand smoke, neither does smoking outdoors.
"Smoking outside is better than smoking indoors but nicotine residues will stick to a smoker's skin and clothing," said Lara Gundel, a co-author of the study.
"Those residues follow a smoker back inside and get spread everywhere. The biggest risk is to young children.
"Dermal uptake of the nicotine through a child's skin is likely to occur when the smoker returns and if nitrous acid is in the air, which it usually is, thenTSNAs will be formed."
Substantial levels of TSNAs were also found in the truck of a heavy smoker, the study says, adding that most vehicle engines emit some nitrous acid that can infiltrate the passenger compartment of a vehicle.
The researchers said: "Implementation of 100 percent smoke-free environments in public places and self-restrictions in residences and automobiles are the most effective tobacco control measures, through elimination of the primary pollution source.
"In buildings where substantial smoking has occurred, replacing nicotine-laden furnishings, carpets and wallboard can significantly reduce exposures to third-hand smoking hazards."