| Dimension | Secondhand Smoke | Secondhand Vape | Difference |
|---|---|---|---|
| Source | Combustion (600-900C) | Heating (150-300C) | Fundamental process difference |
| Known carcinogens | 70+ (IARC Group 1) | 0 proven carcinogens at observed levels | Massive reduction |
| Carbon monoxide | Present (15-55 ppm) | Absent | CO eliminated entirely |
| PM2.5 peak | 200-1,000+ ug/m3 | 22-160 ug/m3 | 5-10x lower |
| Nicotine in air | 1-10+ ug/m3 | 0.1-3.3 ug/m3 | 3-30x lower |
| TSNAs | Present (NNK, NNN) | Absent | Eliminated |
| Proven disease links in bystanders | Cancer, heart disease, stroke, asthma | None proven | Key distinction |
| Odor persistence | Hours to days | Minutes to 1 hour | Faster dissipation |
| Surface residue ("thirdhand") | Significant (tar, nicotine) | Present but lower (nicotine, PG/VG) | Less persistent |
This comparison draws on the same combustion science framework as our vaping vs smoking health comparison — the fundamental difference is combustion vs heating, which determines the toxicological profile of the resulting aerosol.
