E-cigarette popularity has increased and with that another possible source of toxicity.
电子香烟开始变得流行，于是产生了另一种可能的毒性来源。
2
In fact, combined e-cigarette and cigarette use among adolescents in 2014 was higher than total cigarette use in 2009, according to the study.
事实上，据研究发现，2014年同时在抽烟和抽电子烟的青少年数量要比2009年显示的吸烟数据更高。
3
The growing popularity of e-cigarette has prompted debate about their safety and potential to help people quit tobacco smoking and the risk they may encourage some people to take it up.