| Indoor Air Change per Hour (ACH) | Time that Particles Remain Suspended in the Air Before Settling at a 1-m Distance | |
| Aerosols* | Droplets** | |
| ACH = 0 | 6 min - 13 days | 3 sec - 19 min |
| ACH ≥ 1 | 6 min - 1 hour | 3 sec - 19 min |
| ACH ≥ 10 | 3 sec - 6 min | 3 sec - 6 min |