Approximate mean personal exposure concentrations (μg/m3) of respirable dust and cristobalite (assuming a mean cristobalite content of 15% in airborne dust) during the course of the current eruption (April 1996 to August 1999)
| Respirable dust | Cristobalite | |||||
|---|---|---|---|---|---|---|
| Cork Hill* | Salem† | North | Cork Hill | Salem | North | |
| The US (ACGIH) limit for workplace exposure to cristobalite adjusted for 24 hour exposure over 365 days/year is equivalent to 10 μg/m3. | ||||||
| *Assumes evacuation to Salem in June 1997 and then to north of island in August 1997. | ||||||
| †Asumes evacuated to north of island between August 1997 and October 1998. | ||||||
| Sedentary adults | 100 | 60 | 40 | 15 | 10 | 5 |
| Active adults | 140 | 90 | 60 | 20 | 20 | 10 |
| Adults with dusty occupations | 390 | 260 | 180 | 60 | 40 | 30 |
| Children | 200 | 130 | 80 | 30 | 20 | 10 |