Secondhand smoke comes from both the smoke that smokers exhale (called mainstream smoke) and the smoke floating from the end of the cigarette, cigar, or pipe (called sidestream smoke).

二手烟不仅来自吸烟者呼出的烟气（我们称之为主流烟气），而且来自从烟尾、雪茄或者烟管中飘散出的烟气（我们称之为测流烟）。

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Secondhand smoke comes from both the smoke that smokers exhale (called mainstream smoke) and the smoke floating from the end of the cigarette, cigar, or pipe (called sidestream smoke).

二手烟不仅来自吸烟者呼出的烟气（我们称之为主流烟气），而且来自从烟尾、雪茄或者烟管中飘散出的烟气（我们称之为测流烟）。

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