| 1. | It contains more then 4 , 000 chemicals which includes poisons and carcinogens . e . g . tar , nitcoine , carbon monoxide , ammonia , dimethylnitrosamine , formaldehyde , hydrogen cyanide and acrolein . the u . s . environment protection agency has classified secondhand smoke as a group a carcinogen
二手烟雾含有4 , 000多种的化学粒子和气体，当中还包括了焦油、尼古丁、苯并芘等粒子，以及有毒气体如一氧化碳、亚摩尼亚、甲醛、丙烯醛等。 |
