三手烟：一个新发现的健康威胁

 三手烟是大部分民众尚未听闻或认知的新名词，它是指吸烟后残留在物体表面和灰尘中的烟雾污染物。三手烟的重要特征是其中某些化合物可与空气中的某些成份发生化学反应，生成新的有害物质，其毒性可随时间而逐渐加剧。三手烟的主要危害人群为儿童。本文总结了三手烟与二手烟的关联和区别、物理和化学特性、存在场所和污染途径，以及近年来在三手烟成份、检测和毒性等方面的重要研究进展，并展望了未来的研究方向。基于科学依据的三手烟概念及对其危害的认识，将有助于室内和公共场所禁烟，如何预防和清除三手烟也将成为大众关注的现实问题。

Thirdhand Smoke,a Newly Identified Health Threat

The thirdhand smoke (THS) is a new concept, so far unfamiliar to most people. It refers to the tobacco smoke toxicants that remain in indoor surfaces and in dust particles after the cigarettes are extinguished. Certain chemical constituents such as nicotine in the THS can react with atmospheric species to generate secondary hazardous products. The THS becomes more toxic during the aging process. The THS poses a great hazard to infants and young children who live with the smokers. This paper reviews the relationship and differences between the THS and the secondhand smoke (SHS). The physical and chemical properties, as well as the common pollution locations and exposure routes of the THS are discussed. The research progresses concerning the THS in recent years with respect to its composition and chemical transformation, the environmental and biological monitoring, and the cellular/tissue and genetic toxicity are reviewed. Finally, the future research directions and clinical implications of the THS exposure are commented. It is believed that the promotion of the THS concept based on scientific findings will impose a positive impact on the social, economic, and policy-making aspects of the overall tobacco control. How to prevent and cleanup the THS would also be of interest to the general public.