The danger of third-hand smoke

Smoking is a well-known source of indoor air pollutants. As well as the obvious dangers of first‑hand exposure, unintentional inhalation of “second-hand smoke” is also known as a potential health risk. However, the dangers of third-hand smoke may also pose more of a risk than previously thought, according to a study in Environmental Science and Technology.¹

Third-hand smoke is a consequence of the residual smoke that remains on the surface after the cigarette is extinguished. Exposure can occur by re-emission or skin contact with the surface, as well as via other pollutants that can be generated when ozone in the air reacts with the nicotine deposited on the surface.

To better understand this process, researchers used gas chromatography and spectroscopic techniques to study the interaction between nicotine and indoor air on typical indoor surfaces including paper, cotton and cellulose (a component of wood furniture).

Reactions between the nicotine and ozone were found to produce mysomine and cotinine under wet and dry conditions, as well as two unique compounds under humid conditions. These components have been identified in the particulate phase of environmental tobacco smoke and, according to the study, highlight the relevance of indoor surface reactions to the indoor environment. Given the toxicity of some of the products identified, the study indicated that third-hand smoke could pose additional health risks.

1. L.M. Petrick, A. Svidovsky and Y. Dubowski, Environ. Sci. Technol., 45(1), 328–333 (2011).