1 Introduction
Cigarette smoke is a major risk factor in carcinogenesis and heart disease. Among the various compounds in it, free radicals have been found to play ah important role in cigarette smoke-induced cytotoxicity. The cigarette smoke was composed of a gas-phase substance anda solid-phase substance. The solid-phase substance can be cleaned partly by filters; however, the damaging effects of gas-phase cigarette smoke GPCS) are more difficult to prevent. By stimulating lipid peroxidation, GPCS damages cell membrane lipids and proteins and affects the membrane fluidity as well as the activities of membrane-bound enzymes. By this mechanism, GPCS may be implicated in the pathogen-esis of many diseases.