Introduction: The 2006 U.S. Surgeon General's Report found that there is no safe level of exposure to secondhand smoke (SHS). Many smokers attempt to protect others from exposure to SHS; however, it is difficult to assess effectiveness of these behavior changes. There is a need for personal monitoring devices that provide real-time SHS exposure data; at present, there is no device that measures ambient nicotine levels in real time. The development of such a sensor is the objective of this research.
Methods: A nicotine sensing film comprising the conductive polymer polyaniline was linked with a reporting layer, recording changes in chemiresistance due to adsorption of nicotine. Experiments were carried out in a microprocessor-controlled smoking chamber using sidestream smoke from standard reference cigarettes; up to 10 cigarettes were smoked simultaneously. The exposure chamber was calibrated for total suspended particle, carbon monoxide, and nicotine concentrations.
Results: We found significant real-time increases in the resistance of films upon exposure to SHS. The sensors were shown to be sensitive to the number of cigarettes consumed and ambient nicotine and demonstrated reasonable recovery between measurements. The sensors have sufficient sensitivity to detect off-gassing of nicotine or "thirdhand smoke."
Conclusions: A sensing element has been developed that can reliably detect secondhand and thirdhand tobacco smoke in real time through the adsorption of ambient nicotine vapor. The device was calibrated to the number of smoked cigarettes and to nicotine concentration. Development of integrated personal sensors to record exposure to SHS using this technology is currently underway.