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Secondhand Smoke 二手烟

Secondhand smoke is the combination of “sidestream” smoke (the smoke given off by a burning tobacco product) and “mainstream” smoke (the smoke exhaled¹ by a smoker).
二手烟包括“侧流烟”（烟草产品燃烧释放的烟）和“主流烟”（吸烟者呼出的烟）。

People can be exposed to secondhand smoke in cars, the workplace, and public places, such as bars and recreational settings. The source of most secondhand smoke is from cigarettes.
人们可能在汽车、工作场所和公共场所，如酒吧和娱乐场所，暴露于二手烟之下。大部分二手烟来自香烟。

Does secondhand smoke contain harmful chemicals? Yes. Among the more than 7,000 chemicals that have been identified in secondhand tobacco smoke, at least 250 are known to be harmful, for example, hydrogen cyanide, carbon monoxide, and ammonia. At least 69 of the toxic² chemicals in secondhand tobacco smoke cause cancer.
二手烟是否含有有害化学物质？是的。已确定二手烟的烟雾中含有超过7千种化学物质，其中至少250种是有害的，比如氰化氢、一氧化碳和氨。二手烟中至少69种有毒化学物质会导致癌症。