The Aerosol Science: What's Actually in Vape Cloud—and Why It's Not Just 'Water Vapor'

The claim that vape aerosol is 'just water vapor' is wrong—and it has been used, by critics of vaping, to discredit the entire harm reduction argument. The aerosol produced by a vaping device contains propylene glycol, vegetable glycerin, nicotine, flavor compounds, and—depending on the device and the operating conditions—measurable levels of thermal degradation products (formaldehyde, acetaldehyde, acrolein). **The aerosol is not harmless. But it is dramatically less harmful than cigarette smoke—which contains over 7,000 compounds, including at least 70 known human carcinogens, generated by the combustion of tobacco at 900°C. The honest aerosol science: vaping is not safe. Vaping is substantially safer than smoking—by a factor of at least 20 to 1, and probably much more.**

**The thermal degradation products are the primary concern.** When e-liquid is heated to vaping temperatures (typically 200-300°C), the propylene glycol and vegetable glycerin can thermally decompose, producing low levels of carbonyl compounds—formaldehyde, acetaldehyde, acrolein—that are respiratory irritants and potential carcinogens. The levels are dramatically lower than in cigarette smoke (1-5% of smoke levels in most studies), and they are highly dependent on device characteristics and user behavior. **A well-designed device operated at appropriate temperatures produces minimal thermal degradation. A poorly-designed device operated at excessive temperatures ('dry puff' conditions) can produce levels that approach those in cigarette smoke. The device matters. The temperature matters. The user behavior matters.**

**💬 Before reading this, did you think vape aerosol was 'just water vapor'—or did you think it was as dangerous as cigarette smoke? Does knowing the actual chemistry change your assessment of the risk?**