Are e-cigarettes harmful? Can it help people quit smoking?
The U.S. centers for disease control and Prevention (CDC) estimates that e-cigarette is still a new thing and that the health effects of long-term use are unknown. E-cigarettes often contain nicotine, which is harmful to fetal development and cognitive development in people under the age of 25. In addition to nicotine, vapors from e-cigarettes are not entirely harmless. They contain some tiny particles that may cause cancer, and may also contain some heavy metals and volatile compounds . Some studies have also shown that e-cigarettes increase the risk of heart disease and cancer.
Public health England (PHE) released a 113-page report in 2015 detailing the risks associated with e-cigarettes. The report concluded that e-cigarettes are 95percent safer than smoking and that policies should encourage the use of e-cigarettes as a key tobacco control strategy to reduce the harm caused by smoking. Note that "smokers" are encouraged to use e-cigarettes to help them quit smoking . England's department of public health is sticking to its claim that e-cigarettes are 95percent safer than cigarettes in 2018, despite much skepticism. 
In February 2018, the American cancer society (ACS) also issued a position statement: while the long-term effects of e-cigarette use are yet unknown, it can be estimated that e-cigarettes are less harmful than regular cigarettes. The association explicitly encourages people to try e-cigarettes as a smoking alternative. And the clinicians are also suggested to recommend e-cigarettes to smokers as an alternative to conventional cigarettes. It is for sure that e-cigarettes are only a transitional state, and quitting smoking should always be the first choice .
In November 2018, the centers for disease control and Prevention (CDC) made its case to the public. They suggest that smokers should start using an e-cigarette and trying to quit smoking by it. However, it also reminds us that e-cigarettes are not harmless. Teenagers and pregnant women, as well as non-smokers, should not try them because they are less harmful than cigarettes .
After weighing the pros and cons, public bodies in both the UK and the US tend to agree that e-cigarettes are still better for smokers than cigarettes.
E-cigarettes may not help stop smoking
Nicotine replacement products (NRT) are the generic term for a number of smoking-cessation products that are primarily used in nicotine replacement therapy (NRT). Nicotine in cigarettes is an addictive substance. When you quit smoking, you will have a withdrawal reaction.
If nicotine patches, nicotine gum, or nicotine sprays are used to deliver nicotine to the blood during smoking cessation, the withdrawal response can be alleviated and the success rate of smoking cessation can be improved. In 1996, the world health organization (WHO) officially recommended nicotine replacement therapy to all countries. The FDA has also approved at least four legal nicotine replacement products to help people quit smoking. The same seems to be true for e-cigarettes, which the WHO, in fact, calls the "electronic nicotine delivery system" and looks at alongside other nicotine substitutes. But while e-cigarettes are similar to nicotine substitutes, they are also similar to smoking in terms of behavior, so you can't just assume that e-cigarettes will help you quit.
Researches are inconsistent on whether e-cigarettes can help people quit smoking.
For example, a 2014 paper published on JAMA showed no improvement in quit success and no reduction in cigarette consumption among e-cigarette users in a longitudinal analysis of 949 smokers who participated in a twice-yearly online survey. However, at the same time, the author of the paper also said that this survey relies on individual oral reports, and the respondents do not know enough about the usage, frequency, and habits of e-cigarettes .
Other studies have suggested that e-cigarettes can help smokers quit or reduce smoking. A meta-analysis study in 2016 showed that those who chose to quit smoking via e-cigarettes had a 28percent higher probability of successfully quitting smoking than those who did not choose e-cigarettes . A recent study published in the Cochrane systematic review database found that e-cigarettes helped people quit smoking, and it works better than placebo .
Another 2015 meta-analysis showed that smokers were more likely to quit smoking with nicotine-containing nape than without. This suggests that to some extent e-cigarettes do work as well as traditional nicotine replacement therapy. This study even shows that e-cigarettes are more successful than traditional nicotine replacement therapy in getting people to quit smoking (20percent success rate vs 10percent success rate) .
The department of public health credits e-cigarettes with an overall decline in smoking rates from 2011 to 2017.
In the UK, the situation is more optimistic. In 2018, the ministry of public health published a blog saying that e-cigarettes can help people quit smoking, at least in the UK. There are 2.9 million e-cigarette users in the UK, and more than half of it has given up smoking completely. And e-cigarettes are expected to help other 20,000 people quit each year. With the promotion of e-cigarettes, the smoking rate in Britain has been declining year by year, reaching a historical low of 15.5percent, which is only higher than Sweden in the whole of Europe .
To be conservative, according to WHO in 2014, the existing studies are not enough to prove that the use of e-cigarettes can help completely kick the habit of smoking, and the traditional nicotine therapy that has been proved to be effective is preferred .
WHO also believes that although quitting completely is hard, people can smoke and vape at the same time. Since they smokeless cigarettes, e-cigarettes can still be recommended to smokers .
Should e-cigarettes be banned
Should we emphasize that e-cigarettes are 95percent less harmful than cigarettes, or should we emphasize that e-cigarettes are harmful? It's a dilemma for public health.
If policies are biased toward promoting e-cigarettes as less harmful than cigarettes, then smokers are more likely to switch to e-cigarettes and cigarettes are less harmful. However, once teenagers know that e-cigarettes are less harmful, they may start vaping. It may even have increased smoking overall, which backfires. But just saying that e-cigarettes are harmful will cause smokers to distrust e-cigarettes and scare away smokers who want to change to e-cigarettes. In 2013, only 7 percent of Britons were under the mistaken belief that e-cigarettes were as bad as cigarettes, compared with 25 percent in 2018. The department of public health (moh) said that some of the comments focused too much on the dangers of e-cigarettes and ignored the comparison with cigarettes, which affected the public's correct understanding of the dangers of e-cigarettes and cigarettes. 
In the dilemma mentioned above, the specific side to focus on varies from country to country
The UK as a whole is inclined to support the promotion of e-cigarettes. The propaganda emphasizes that "e-cigarettes are less harmful than cigarettes", which can dispel smokers' doubts about the safety of e-cigarettes and emphasize the comparison between e-cigarettes and cigarettes. In December 2018, public health England (PHE) produced a short film, using cotton balls, to show people the difference between one month of smoking cigarettes and one month of e-cigarettes using .
Britain seems more optimistic about young people using e-cigarettes.
For example: in January 2019, a charity called cancer research UK said there was a lack of evidence in the UK that e-cigarettes were leading teenagers to smoke. Young people's smoking rate has been declining, and the probability of non-smoking young people using e-cigarettes is very low, around 0-1percent .
The document further points out that in Europe, although young people are more willing to try e-cigarettes, young people end up using e-cigarettes less than older people, which indicates that trying e-cigarettes does not cause smoking .
In December 2018, the department of public health released a short film showing that e-cigarettes are less harmful than traditional cigarettes. Call on the Public not to choose to smoke rather than try e-cigarettes because of the false perception that e-cigarettes are as harmful as cigarettes
There are more young people in the United States use e-cigarettes, so the US has a more cautious attitude toward e-cigarettes
From 2017 to 2018, the percentage of high school students exposed to e-cigarettes soared from 11.7 percent to 20.8 percent, up as much as 78 percent, according to the national youth tobacco survey. The number of junior middle school students increased from 3.3percent to 4.9percent, which increased by 48percent. In one year, there were 1.5 million people. It is estimated that 3.6 million middle school students have been exposed to e-cigarettes. (contact counted as having tried e-cigarettes within 30 days of the survey)
Both the material and the department of public health promo were released in December 2018, but different attitudes were expressed. This material emphasizes the conclusion that e-cigarettes are harmful, that e-cigarettes are not effective in quitting smoking, and that e-cigarettes are more likely to cause young people to smoke .
In a word, if you are a heavy smoker who has failed many times to quit smoking; e-cigarettes may be a choice to quit smoking. But if you've never smoked, don't try any e-cigarettes. At the same time, e-cigarettes are not completely harmless. It's just less harmful than cigarettes. There is a debate about whether e-cigarettes can help people to stop smoking.
Hartmann‐Boyce, J., McRobbie, H., Bullen, C., Begh, R., L. F., & Hajek, P. (2016). Electronic cigarettes for smoking . The Cochrane Library.
McNeil, A., Brose, L. S., Calder, R., Hitchman, S. C., Hajek, P., & McRobbie, H. (2015). E-cigarettes: an evidence update. A report commissioned by Public Health England. Public Health England, 111.
Grana RA, Popova L, PM. A Analysis of Electronic Cigarette Use and Smoking . JAMA Intern Med. 2014;174(5):812–813. doi:10.1001/jamainternmed.2014.187
Rahman, M. A., Hann, N., Wilson, A., Mnatzaganian, G., & Worrall-Carter, L. (2015). E-cigarettes and smoking : evidence from a systematic review and meta-analysis. PloS one, 10(3), e0122544. doi:10.1371/journal..0122544
Kalkhoran, Sara; Glantz, Stanton A (2016). "E-cigarettes and smoking cessation in real-world and clinical settings: a systematic review and meta-analysis". The Medicine. 4 (2): 116–128.
cancer research UK
Youth Tobacco Use: Results from the National Youth Tobacco Survey
Smokefree ‘Health Harms’ – Impact of smoking vs vaping demonstration
electronic nicotine delivery systems report by WHO
About Electronic Cigarettes (E-Cigarettes)
Public health matters-GOV.UK