Tobacco harm reduction (THR), is the replacement of tobacco cigarettes with lower risk products, to reduce tobacco related death and disease. THR has been controversial out of fear that tobacco companies cannot be trusted to produce and market products, that will reduce the risks associated with tobacco use. E cigarettes can reduce smokers' exposure to carcinogens and other toxic substances found in tobacco. Tobacco smoke contains 100 known carcinogens, and 900 potentially cancer causing chemicals, none of which has been found in more than trace quantities in the cartridges or aerosol of e cigarettes. According to a 2011 review, while e cigarettes cannot be considered "safe" because there is no safe level for carcinogens, they are doubtless safer than tobacco cigarettes.
A core concern is that smokers who could have quit completely will develop an alternative nicotine addiction insteadA 2014 review stated that promotion of vaping as a harm reduction aid is premature, but in an effort to decrease tobacco related death and disease, e cigarettes have a potential to be part of the harm reduction strategy.
Another review found e cigarettes would likely be less harmful than traditional cigarettes to users and bystanders. The authors warned against the potential harm of excessive regulation and advised health professionals to consider advising smokers who are reluctant to quit by other methods to switch to e cigarettes as a safer alternative to smoking. A 2015 Public Health England report concluded that e cigarettes "release negligible levels of nicotine into ambient air with no identified health risks to bystanders". A 2014 review recommended that regulations for e cigarettes could be similar to those for dietary supplements or cosmetic products to not limit their potential for harm reduction. A 2012 review found e cigarettes could considerably reduce traditional cigarettes use and they likely could be used as a lower risk replacement for traditional cigarettes, but there is not enough data on their safety and efficacy to draw definite conclusions. E cigarette use for risk reduction in high-risk groups such as people with mental disorders is unavailable.
A 2014 Public Health England report concluded that there is large potential for health benefits when switching from tobacco use to other nicotine delivery devices such as e cigarettes, but realizing their full potential requires regulation and monitoring to minimize possible risks. They found that a considerable number of smokers want to reduce harm from smoking by using these products. The British Medical Association encourages health professionals to recommend conventional nicotine replacement therapies, but for patients unwilling to use or continue using such methods, health professionals may present e cigarettes as a lower-risk option than tobacco smoking. The American Association of Public Health Physicians (AAPHP) suggests those who are unwilling to quit tobacco smoking or unable to quit with medical advice and pharmaceutical methods should consider other nicotine containing products such as electronic cigarettes and smokeless tobacco for long term use instead of smoking. In an interview, the director of the Office on Smoking and Health for the U.S. federal agency Centers for Disease Control and Prevention (CDC) believes that there is enough evidence to say that using e cigarettes is likely less harmful than smoking a pack of conventional cigarettes. However, due to the lack of regulation of the contents of e cigarettes and the presence of nicotine, the CDC has issued warnings. A 2014 WHO report concluded that some smokers will switch completely to e cigarettes from traditional tobacco but a "sizeable" number will use both This report found that such "dual use" of e cigarettes and tobacco "will have much smaller beneficial effects on overall survival compared with quitting smoking completely."