'Thirdhand smoke' bigger health hazard than suspected

The study, published in "Environmental Science & Technology" journal, extends the known health risks of tobacco to people who encounter the smoke exhaled by smokers - the so-called secondhand or passive smoking.

Yael Dubowski and colleagues at the Civil and Environmental Engineering department of Israel Institute of Technology in Haifa describes "thirdhand smoke" as the residual smoke contamination that remains on surfaces after a cigarette is extinguished. They note that "thirdhand smoke" is a newly recognised contributor to the health risks of tobacco and indoor air pollution due to the role of indoor surfaces.

Their studies show that that nicotine in "thirdhand smoke" can react with ozone or nitrogen oxides in indoor air on surfaces like clothing and furniture to form other harmful pollutants.    

"The high absorption capacity of nicotine to household furnishings and clothing make these surfaces a potentially dominant source for exposure," the report said.
"Exposure to them can occur to babies crawling on the carpet, people napping on the sofa, or people eating food tainted by 'thirdhand smoke'," the American Chemical Society, which publishes the journal, has warned.

In an effort to learn more about "thirdhand smoke", the scientists studied interactions between nicotine and indoor air on a variety of different materials, including cellulose (a component of wooden furniture) cotton, and paper to simulate typical indoor surfaces. They found that nicotine interacts with ozone in indoor air to form potentially toxic pollutants on these surfaces.

Cumulative exposures to these airborne pollutants may be greater for an infant than an adult when both breathing rate and body weight are considered, the scientists said.
The scientists conclude that "given the toxicity of some of the identified products and that small particles may contribute to adverse health effects, the present study indicates that exposure to 'thirdhand smoke' may pose additional health risks".