被动吸烟是不吸烟者在吸烟环境中呼吸烟草的燃烧产物。烟草燃烧产生主流烟和从流烟 ,主流烟经过主动吸烟者的肺过滤后排放到空气中 ;从流烟较主流烟含有较多的氨、苯、CO、CO2 、尼古丁和其它致癌物质。1990年环境保护机构将从流烟定为一种致癌物质 ,并指出部分人吸入后可能患 Passive smoking is the product of non-smoker breathing tobacco in a smoking environment. Tobacco combustion produces mainstream smoke and from stream smoke, the mainstream smoke is filtered by the active smoker’s lungs and discharged into the air; from the mainstream smoke smoke contains more ammonia, benzene, CO, CO2, nicotine and other carcinogens. In 1990, the Environmental Protection Agency will decide to smoke from the smoke as a carcinogen, and pointed out that some people may be affected after inhalation