| Value | Category |
|---|---|
| 1 | No, I have not used an electronic cigarette in the past 30 days |
| 2 | Yes, with nicotine in crystals or salts |
| 3 | Yes, with liquid nicotine |
| 4 | Yes, without nicotine |
| 5 | Yes, both without and with nicotine |
| 6 | Yes, but I don't know if with or without nicotine |
| Sysmiss |