Estimated proportion (%) of days with differing levels of dustiness based on measurement data (tables 3–5), reported levels of volcanic activity (MVO), and information from interviews with islanders
| Period | ||||
|---|---|---|---|---|
| 1996* | 1997 | 1998 | 1999† | |
| Note that Cork Hill has been unoccupied since mid 1997 and Salem was officially unoccupied between August 1997 and October 1998. | ||||
| *April to December. | ||||
| †January to August—rainfall data used to estimate proportion of days between January and April. | ||||
| Proportion of days with alert level dust concentrations (>300 μg/m 3 ) | ||||
| Cork Hill | 2 | 10 | 0 | 1 |
| Salem | 1 | 5 | 0 | 1 |
| North | 0 | 2 | 0 | 0 |
| Proportion of days with very high dust concentrations (100–300 μg/m 3 ) | ||||
| Cork Hill | 5 | 20 | 1 | 5 |
| Salem | 2 | 5 | 1 | 5 |
| North | 1 | 2 | 1 | 5 |
| Cork Hill | 10 | 50 | 15 | 50 |
| Proportion of days with raised dust concentrations (50–100 μg/m 3 ) | ||||
| Salem | 5 | 30 | 15 | 55 |
| North | 1 | 10 | 5 | 20 |