Table 4.
‘Dust event’ frequency for each site computed over their entire measurement period, the fraction of those cases which were accompanied by enhancement of at least one of the four metal/metalloids shown (Pb, As, Cu and Zn), and the fraction of events that exhibited an increase in the concentration of each specific metal/metalloid.
| Site | Dust event' frequency (per year) |
Fraction of cases with metal/metalloid enhancement |
Pb (%) |
As (%) |
Cu (%) |
Cu (%) |
|---|---|---|---|---|---|---|
| Chiricahua | 7 | 63% | 42 | 21 | 37 | 49 |
| Organ Pipe | 7.3 | 78% | 49 | 10 | 55 | 63 |
| Queen Valley | 3 | 55% | 35 | 27 | 41 | 41 |
| Tonto | 6.4 | 64% | 43 | 15 | 38 | 59 |
| Saguaro West | 7.1 | 89% | 56 | 16 | 63 | 81 |
| Saguaro NM | 4 | 82% | 52 | 18 | 54 | 73 |
| Phoenix | 6.8 | 88% | 70 | 21 | 68 | 78 |