在美国自从1954年采用过滤烟咀以来,纸烟释放出的烟焦油和烟硷含量已大大下降。一般不带过滤烟咀的纸烟,由于烟草品种的选择,采用匀化烟草和其他方法,它们所释放出的烟焦油和烟硷含量也较以前显著减少。本文报导了关于烟焦油和烟硷含量降低与吸烟者支气管粘膜上皮组织学改变之间的关系。实验者分成两组:A组病人死于1955—1960;B组病人死于1970—1977。 In the United States since the filter cigarette holder was adopted in 1954, the content of tobacco tar and haze released from cigarette paper has been greatly reduced. Tobacco cigarettes, which generally do not have a filter cigarette holder, have a significantly reduced content of smoke tar and haze as a result of the choice of tobacco varieties, using homogenized tobacco and other methods. This article reports on the relationship between the reduction in smoke tar and haze levels and the histological changes in bronchial mucosal epithelium in smokers. The experimenters were divided into two groups: Group A patients died from 1955 to 1960; Group B patients died from 1970 to 1977.