Is It "Vapor", "Aerosol", or "Particulate Matter"? What Should We Actually Call The Clouds E-Cigs Create?

E-cigarette vapor, e-cig aerosol, electronic cigarette particulate matter—in all of the articles that are being published on electronic cigarettes there seems to be a confusion on what to call the material that electronic cigarettes create.

E-cigarettes have grown in popularity over the past few years and in that time the term “vapor” has become the common term for what an e-cigarette creates. Although it makes sense, since an e-cig does “vaporize” the e-liquid, but technically the term shouldn’t be “vapor”. The paragraphs below will explain the different terms that have been used to label the material created by your e-cig.

So What Is Vapor?

In a regular definition of the term, vapor is the gas phase of something that is usually a liquid. In the glass of water that is in front of you tiny bits of that water are constantly evaporating into the air and that is “water vapor”. If the temperature of the liquid becomes warmer or more pressure is added, more of those molecules will escape the water and turn into vapor. This applies to any matter that is liquid.

So in turn this does mean that e-cig “vapor” does contain some vapor, but it is still mostly in its liquid phase. Meaning it contains very tiny droplets of the liquid suspended in the air, not actually in a gas phase, being that they are “suspended” and are physically mixed with the air. This suspension in the air is not vapor but an aerosol.

What Is An Aerosol?

Definitions of aerosol usually include solid particles that are suspended in the air and not just liquid droplets. For example, smoke could be considered an aerosol since it has both solid and liquid particles in it that are suspended in the air.

So, in its truest definition, the material that an e-cigarette produces should actually be called liquid aerosol, as the e-liquid doesn’t completely vaporize, rather it leaves very tiny liquid particles that mix with the air around you. In normal circumstances, the area that you are vaping in allows for the very tiny particles to evaporate quickly, this is why the “vapor” disappears very quickly. Unless of course you are at a cloud-chasing competition where huge clouds are being blown out changing the gas content of the air and suddenly it looks like you are in a cloud.

You should also know that matter being labeled an “aerosol” also means it is stable enough to be one. With normal air conditions e-cig “vapor” disappears very quickly so it is not really stable enough to be called an “aerosol”. But scientists often call the material “aerosol” even though it isn’t as stable as a usual aerosol, but it is still a practical label for it.

But What About Those Reporters Who Call It “Particulate Matter”?

Particulate matter by common scientific definition is anything that is suspended as an aerosol. With the definition of aerosol above this would lead to someone being able to say that droplets can be called particles, but particles are very tiny solid objects. So this is an inexact label and saying that liquid droplets are particles is misleading for scientific purposes.

Particles, as solids retain their size and shape, so the particle itself can cause damage. Whereas breathing in liquid droplets poses no damage risk, the tiny liquid droplets will just land and get absorbed conforming to the area it hits; rather than with a solid particle that could build up. You can think of this tiny particle like the tar that is in tobacco cigarette smoke and how it being a solid particle just clings and builds up in the lungs.

So What Should We Actually Call The Cloud That E-Cigs Create?

With the definitions above, e-cigarette vapor is definitely NOT particulate matter, but rather the true scientific title should be liquid aerosol. It isn’t actually a vapor as all of the liquid isn’t completely vaporized, rather suspended—but calling it “vapor” is a little bit catchier. :)