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Introduction Thirdhand cigarette smoke is the fraction of cigarette smoke that remains in the environment long after a cigarette is extinguished. Methods The Truth Tobacco Industry Documents collection at the University of California San Francisco was searched for information on thirdhand smoke. Results In 1991, scientists at Philip Morris Inc conducted some of the first studies on thirdhand cigarette smoke. For 110 days, 8 hours a day, they ran sidestream cigarette smoke through a 30 m3 room that contained carpet, curtain, and textured wallpaper. The room was ventilated with clean air every night. By comparing the chemicals in the air during the 8-hour smoking period and during the clean air ventilation period, they showed that some smoke chemicals persist in the air 12 hours after smoking. By extracting the nicotine and nitrosamines from samples of the carpet, curtain, and wallpaper, they found that high concentrations of nicotine and the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) persisted in the room for more than 50 days; that surface chemistry affected nitrosamine concentrations; and that the concentration of NNK in the room, 110 days after the last cigarette was extinguished, could exceed the mass of NNK that entered the room as smoke. Conclusions These data, from a controlled environment where the total number of cigarettes smoked is known, provide further evidence that cigarette smoke chemicals remain in the environment for months after smoking, that they reemit back into the air, and that they react to form new toxins and carcinogens. Smoke-free policies are the best method to reduce exposure to thirdhand smoke. Implications This unpublished, original research from Philip Morris Inc demonstrates that majority of the nicotine and tobacco-specific nitrosamines in the secondhand smoke from each cigarette smoked indoors remains on indoor surfaces for months after the cigarette is extinguished. It also demonstrates that elevated concentrations of nicotine, ammonia, formaldehyde, and the gas-phase nitrosamine, N-nitrosopyrrolidine, can be found in the air for more than 12 hours after smoking; that surface chemistry affects nitrosamine formation and persistence; and that the amount of the carcinogenic nitrosamine NNK that persists months after smoking ends can exceed the amount that actually came out of the cigarettes.

Advances with para-hydrogen induced polarization open up new fields of applications for portable low-field NMR. Here we report the possibility of tracing drugs down to the micromolar regime. We could selectively polarize nicotine quantities similar to those found in one cigarette. Also less than 1 mg of harmine, a drug used for treatment of Parkinson's disease, and morphine extracted from an opium solution were detectable after polarization with para-hydrogen in single-scan (1)H-experiments. Moreover, we demonstrate the possibility to selectively enhance and detect the (1)H-signal of drug molecules with PHIP in proton rich standard solutions that would otherwise mask the (1)H NMR signal of the drug.