Table 3.
Comparison of PM10, PM2.5, and UFP (adapted from Schraufnagel [30])
| Characteristics | PM10 | PM2.5 | UFP |
|---|---|---|---|
| Aerodynamic diameter (mm) | 2.5–10 | 2.5–0.1 | < 0.1 |
| Deposition in alveolar space | No | No | Yes |
| Surface area/mass ratio | + | ++ | +++ |
| Organic carbon content | + | ++ | +++ |
| Elemental carbon content | +++ | ++ | + |
| Metal content | +++ | ++ | + |
| Exposure metrics | Mass | Mass | Particle number or surface area |
| Central monitoring sites | Yes | Yes | None |
| National Ambient Air Quality Standards (NAAQS)/US EPA | 150 mg/m3 (24 h) | 35 mg/m3 (24 h) | None |