Environmental concentrations of PM10 (containing approximately 10% crystalline silica) in μg/m3 as estimated from DUSTTRAK measurements made between June 1997 and September 1998
| Little volcanic ash | High volcanic ash, dry | |||
|---|---|---|---|---|
| Wet | Dry | Wind not from south | Southerly wind | |
| The ranges of measured 15 minute (approximate) means at each location are shown in brackets. High ash days are those in which indoor surfaces are covered with a visible layer of dust. | ||||
| Plymouth | 35 | 150 (70–180) | >1000 (1000–2000) | Not measured |
| Cork Hill | 30 (19–35) | 60 (35–75) | 1000 (1000–3500) | Not measured |
| Salem | 20 (15–30) | 30 (25–130) | 200 (55–500) | 800 (100–1000) |
| North | 20 (15–25) | 30 (20–60) | 50 (45–80) | 500 |