The term “vape smoke” is technically inaccurate because vaping does not involve combustion. The visible cloud exhaled from an electronic cigarette is an aerosol, which is a suspension of fine liquid particles in a gas. This aerosol is fundamentally different from smoke, which is a byproduct of burning material. Vaping involves heating a liquid solution, known as e-liquid, until it vaporizes and then condenses into this visible mist upon cooling. Once exhaled, the aerosol’s components follow specific physical and chemical pathways into the environment.
What Vaping Aerosol Is Made Of
The primary ingredients forming the aerosol cloud are the solvent carriers: Propylene Glycol (PG) and Vegetable Glycerin (VG). These compounds generate the visible mist and are common substances found in many food and cosmetic products. The e-liquid solution also contains nicotine and various chemical flavorings.
When the e-liquid is heated by the device’s coil, chemical reactions can occur, producing additional compounds. Trace amounts of metals, such as nickel, lead, or tin, can leach from the heating element itself into the aerosol during the vaporization process. High temperatures can also cause the base liquids to break down, forming volatile organic compounds (VOCs) and aldehydes, such as formaldehyde and acetaldehyde. These irritants or toxins are then expelled into the surrounding environment.
How the Aerosol Disperses in the Air
Once the aerosol is exhaled, the physical process of dispersion begins immediately. The exhaled cloud consists of ultrafine liquid droplets, typically measuring around 150 nanometers in diameter. These liquid droplets are highly volatile and begin to evaporate almost instantly into the surrounding air.
This rapid evaporation causes the visible cloud to disappear quickly, often within a few seconds. The PG and VG components transition back into a gaseous state, or vapor, becoming invisible to the naked eye. The primary mechanism for the disappearance of the visible cloud is this phase change, not simply dilution or ventilation.
The concentration of airborne particles returns to background levels much faster than with conventional smoke, which is composed of more stable, non-volatile particles that persist longer in the air. While the visible cloud dissipates rapidly, the invisible compounds, including nicotine and volatile organic compounds, are dispersed into the room’s atmosphere. This dispersion occurs through airflow dynamics, causing the concentrations of these compounds to spread throughout the indoor space.
Residual Settling on Surfaces
While the visible aerosol quickly evaporates and disperses, certain non-volatile components do not transition back into a gas and instead settle onto nearby surfaces. This process is often referred to as thirdhand exposure, representing the residue left behind after the airborne particles have dispersed. Nicotine is one of the most prominent components that deposits onto materials like walls, floors, clothing, and furniture.
Studies have shown significant increases in nicotine residue on surfaces such as glass windows and floors in rooms where vaping has occurred. The residue is persistent and can remain on these surfaces for extended periods, from days to months.
This surface residue is concerning because settled nicotine can react with common indoor air pollutants, such as nitrous acid, to form new secondary compounds. These secondary compounds can include tobacco-specific nitrosamines (TSNAs), which are known carcinogens.
Young children are particularly susceptible to this exposure. They often crawl on floors and engage in hand-to-mouth behaviors, potentially ingesting or absorbing the residues through their skin. The chemical fate of the aerosol, therefore, is a two-part process: rapid airborne dispersion of the bulk material and slow, persistent settling of the non-volatile chemical residues.