| ISO Class | Average number of air changes per hour |
| ISO 5 | 240 – 360 air changes per hour (unidirectional airflow) |
| ISO 6 | 90 – 180 air changes per hour |
| ISO 7 | 30 – 60 air changes per hour |
| ISO 8 | 10 – 25 air changes per hour |
| Conventional building | 1 – 2 air changes per hour |
| FS Cleanroom Class | ISO Equivalent Class | Air Change Rate |
| 1 | ISO 3 | 360 – 540 |
| 10 | ISO 4 | 300 – 540 |
| 100 | ISO 5 | 240 – 480 |
| 1000 | ISO 6 | 150 – 240 |
| 10000 | ISO 7 | 60 – 90 |
| 100000 | ISO 8 | 5 – 48 |
Recommended Air Changes and Ceiling Coverage
| ISO Class | Air Changes Per Hour | Ceiling Coverage |
| ISO 1 | 500 – 750 | 80 – 100% |
| ISO 2 | 500 – 750 | 80 – 100% |
| ISO 3 | 500 – 750 | 60 – 100% |
| ISO 4 | 400 – 750 | 50 – 90% |
| ISO 5 | 240 – 600 | 35 – 70% |
| ISO 6 | 150 – 240 | 25 – 40% |
| ISO 7 | 60 – 150 | 15 – 25% |
| ISO 8 | 5 – 60 | 5 – 15% |
