"Are e-cigarettes safe?" It's the question that almost every smoker asks before trying e-cigarettes for the first time -- and it has no simple answer. Many health experts believe that vaping could be a significantly less risky alternative to smoking. Other experts hesitate to recommend vaping because e-cigarettes still have many unknown factors. In this article, we'll try to present a balanced view that explains the positions of both sides.

There is one thing about which everyone can agree: Nicotine is a powerfully addictive substance. Vaping is an alternative for smokers who can't -- or don't want to -- quit. If you don't use nicotine already, don't start.

Vaping and Smoking Are Fundamentally Different

Apart from the fact that they both contain nicotine, e-cigarettes and tobacco cigarettes have almost nothing in common. When you vape, the vapour that you inhale is an aerosol of propylene glycol, vegetable glycerin, nicotine and flavours. When you smoke, you inhale the products of combustion. Tobacco smoke does contain nicotine, but it also contains tar, carbon monoxide and the products of various chemical reactions. Tobacco smoke also contains the many additives that tobacco companies use to make reconstituted tobacco taste better. The products of tobacco combustion are so complex that we are still learning about the full extent of smoking's effect on the body.

The Safety of Nicotine

Although it is an addictive substance, scientists generally agree that nicotine use among adults may not be particularly harmful. Since it is a stimulant, nicotine sharpens the mind and improves memory. Researchers are attempting to determine whether nicotine may have a positive effect on conditions such as Alzheimer's, Parkinson's disease and ADHD. In those who do not have heart disease, are already addicted to nicotine and cannot quit, there seems to be little harm in continuing nicotine usage as long as no smoke is involved.

The Known Factors of Smoking

Smoking causes more preventable deaths than anything else known. It kills millions of people around the world per year. Hundreds of thousands of non-smokers also die yearly from second-hand smoke. We may not know everything about the way in which nicotine interacts with the body, but we do know that tar is deadly. About half of the people who start smoking -- and never quit -- will eventually die from their habit. By the year 2100, as many as 1 billion people will have died from smoking.

The Unknown Factors of Vaping

So, we know that switching from smoking to using only nicotine is likely to reduce harm among those who already smoke and can't or won't quit. We also know that nicotine is the only active ingredient in e-cigarettes. Here's what we don't know:

• Are propylene glycol and vegetable glycerin safe to inhale?
• Are e-liquid flavours safe to inhale?
• Does an e-cigarette atomizer produce fine metal particles that could potentially be dangerous?
• Do wicks made from cotton and other compounds release harmful substances when subjected to high temperatures?

At present, researchers studying e-cigarettes are focusing their energy on determining whether e-cigarettes are safe in general terms. Specific research topics -- such as whether some flavours are safer than others -- have not received much attention because there is still so much more general research to be done.

Are There Any Scientific Studies About the Safety of E-Cigarettes?

There have been many studies about the safety of e-cigarettes. Most have produced positive results. These are a few:

• A 2014 study suggests that there is "no apparent concern" about the safety of those who inhale second-hand vapour.
• A 2014 study suggests that asthmatics who smoke can improve their lung health by switching to e-cigarettes.
• A 2015 study suggests that e-cigarettes are not as addictive as tobacco cigarettes and are comparable to nicotine gum in their addiction potential.
• A 2016 study suggests that switching to e-cigarettes can reduce the body's level of known carcinogens such as benzene and acrylonitrile. A 2017 study produced similar results.
• A 2017 study suggests that e-cigarettes are responsible for drastically decreased smoking rates in the United States.
• A 2017 study suggests that e-cigarette vapour has far less potential to cause cancer than tobacco smoke.
• 2019 Study: A Randomized Trial of E-Cigarettes versus Nicotine-Replacement Therapy.
• 2019 Vaping in England: Evidence update summary February 2019

In spite of this positive news, note that there isn't a single study suggesting that e-cigarettes are safe in absolute terms. The studies suggest that vaping is the better option for those who already smoke. If you do not smoke, you should not vape.

What Do Health Authorities Say About E-Cigarettes?

Because e-cigarettes still have so many unknown factors, the world's health authorities have struggled to determine how to regulate e-cigarettes and what to tell the public about them. Among the world's leading western nations, the United Kingdom is perhaps the most in favour of vaping. The website of the UK National Health System says that "e-cigarettes are a great way to help combat nicotine cravings and carry a fraction of the risk of cigarettes." In the United States, the Food and Drug Administration has delayed regulating e-cigarettes to "encourage innovation that has the potential to make a notable public health difference." Other nations -- such as Japan, Thailand and Brazil -- have banned e-cigarettes. Some nations have banned only e-cigarettes containing nicotine. The differing attitudes toward e-cigarettes reflect the fact that vaping has not existed long enough for us to fully understand its long-term effects.

Are E-Cigarettes Safe for You? Ask Your Doctor

Ultimately, you are the only one who can determine whether switching to e-cigarettes is the right decision for you. We recommend drawing your own conclusion from all of the scientific information available here and elsewhere. If you are a committed smoker who can't or won't quit, ask your doctor whether vaping may be a safer alternative.

Want to learn more about e-cigarettes? Read our vaping beginner's guide.