Two words describing different things
In physics, vapour refers to a substance in its gaseous phase; aerosol describes solid particles or liquid droplets suspended in a gas. A visible cloud should not be interpreted as proof that everything in it is water. For electronic cigarettes, the emitted mixture can include a particle phase and gaseous components: studying it requires more than a photograph.
Spain’s National Plan on Drugs mentions fine particles and substances emitted by these products in indoor spaces. That description helps explain why “it fades away” and “it contains nothing relevant” are different claims. An emission becoming invisible is not an analysis of what remains in the air. National Plan on Drugs: electronic cigarettes
The liquid and the emission are two samples
Imagine a report with two clearly identified envelopes. One corresponds to the liquid in the tank; the other to a sample collected from the aerosol during a test. Although they come from the same product, they answer different questions. The first characterises the starting material. The second examines what the system emits under particular conditions.
The European Commission’s SCHEER opinion examines substances and exposures in the aerosol, including aldehydes and metals. It also distinguishes levels of evidence according to the effect assessed. Reading it shows why a single figure about the liquid cannot summarise every question about emissions. European Commission: SCHEER opinion on electronic cigarettes
Detection is not a complete risk calculation
If a news story says “a substance was detected”, questions remain. In what amount? Using which method? In how many samples? Under which conditions? Were equivalent products compared? These are not excuses to ignore a finding; they are the details needed to interpret it correctly.
Nor is it reasonable to move to the opposite extreme and offer a guarantee: failing to detect something in one test does not establish its absolute absence from every product. A measurement has a scope, a limit and a sample. The same logic applies when reading a hemp certificate of analysis: the result matters, but so does the question asked of the laboratory.
An evidence scale is more useful than an adjective
SCHEER published its opinion in 2021 and assessed effects against not smoking. It distinguished moderate, weak and other categories of evidence according to the outcome studied, and highlighted the need to investigate long-term effects. Citing it as though every section had the same certainty, or as though it settled every comparison between products, distorts the document. European Commission: SCHEER opinion on electronic cigarettes
A good explanation can acknowledge two things at once: there are reasons for concern, and some estimates remain uncertain. That combination is more informative than a context-free list of chemical names or a promise of cleanliness based on how the cloud looks.
Eyes observe; methods compare
Think of two photographs of fog: lighting may make one look much denser. Something similar happens when emissions are interpreted visually: an image does not give concentrations or identify substances. To compare, look for the sample, test and conditions. Aerosol is less evocative than vapour, but it lets us ask much better questions.
Take this with you
A visible cloud is not a measurement. Understanding an aerosol requires distinguishing composition, amount, test conditions and the scope of the evidence.
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