sentences:  Since currently approved smoking cessation methods have a 90% failure rate, the use of e-cigarettes as a prominent THR modality is likely to substantially reduce tobacco-related illness in the United States, with the potential to save 4.8 million lives over the next 20 years.A survey of UK adults found that over two thirds of ex-smokers and over one third of current smokers report that one of the main reasons they use e-cigarettes is to help them stop smoking completely.Research into the safety and efficacy of e-cigarettes for smoking cessation, published up until January 2016, is limited, but suggests a potential increase in long term smoking cessation using e-cigarettes containing nicotine compared to those without, with no increased health risk compared to smokers with medium term use (two years or less).