Characteristics of disposable and refill e-liquids by nicotine class
| Product type | Absent (n=4189) | Free-base (n=21 628) | NAIC (n=2961) | NSI (n=856) |
| Nicotine (or nicotine equivalent) concentration (mg/mL) | 0 | 6 (2–12) | 11 (6–20) | 14 (7–25) |
| Number of ingredients | 6 (2–13) | 8 (5–15) | 16 (9–34) | 20 (11–30) |
| Number of flavour ingredients | 3 (0–9) | 4 (1–11) | 12 (5–30) | 17 (7–27) |
| Flavour ingredients concentration (mg/mL) | 1.8 (0–25.7) | 7.4 (0.3–30.0) | 21.5 (10.7–47.1) | 31.0 (14.9–69.6) |
Values are median (IQR) values for the parameters mentioned. Nicotine classes: absent, nicotine absent; free-base, free-base nicotine.
NAIC, nicotine–organic acid ingredient combination; NSI, nicotine salt ingredient.