Cigarette smoke contains known carcinogens.香烟中含有多种已知的致癌物。Both are common pollutants and suspected carcinogens.两者都是常见污染物和可疑致癌物。The American government classifies both asbestos and environmental tobacco smoke as class one carcinogens.美国政府将石棉和环境中的香烟烟雾列为第一类致癌物。