Table 2.
Inhalable, thoracic, and respirable factors for each stage obtained from ACGIH/ISO size-selective curves and Simpson's rule
| Stage | Size range (㎛) |
Respirable factors | Thoracic factors | Inhalable factors | ||
|---|---|---|---|---|---|---|
| Lower limit | Upper limit | Midpoint∗ | ||||
| 1 | 21.3 | 42 | 31.55 | 0.000 | 0.010 | 0.580 |
| 2 | 14.8 | 21.1 | 17.95 | 0.000 | 0.104 | 0.671 |
| 3 | 9.8 | 14.8 | 12.30 | 0.005 | 0.338 | 0.740 |
| 4 | 6 | 9.8 | 7.90 | 0.065 | 0.669 | 0.812 |
| 5 | 3.5 | 6 | 4.75 | 0.360 | 0.861 | 0.876 |
| 6 | 1.55 | 3.5 | 2.53 | 0.819 | 0.930 | 0.930 |
| 7 | 0.93 | 1.55 | 1.24 | 0.962 | 0.964 | 0.964 |
| 8 | 0.52 | 0.93 | 0.73 | 0.979 | 0.979 | 0.979 |
| Backup | 0 | 0.52 | 0.26 | 0.992 | 0.992 | 0.992 |
ACGIH, American Conference of Governmental Industrial Hygienists; ISO, International Organization for Standardization; LL, lower limit; MP, midpoint; UL, upper limit.
∗
The midpoint of the lower and upper limits for each stage {MP = [(UL − LL)/2] + LL}.