Table 2: Criteria for issuing volcano alerts.
| Level | SO2* | Action for susceptible subjects | Action for healthy subjects |
| 1 | > 0.2 | Stay inside; If any symptoms are noticed, wear gas mask. | |
| 2 | > 0.6 | Put gas mask on and leave the facility or go to an area with lower SO2 levels. | Avoid outdoor exercise |
| 3 | > 2.0 | Stay inside; If any symptoms are noticed, wear gas mask. | |
| 4 | > 5.0 | Wear gas mask on and leave the facility or go to an area with lower SO2 levels. |
*5 min average SO2 concentration (ppm).