| Fabric permeability to allergens | |||
| Airflow through fabric | Mite | Cat | |
| Plastic or vinyl covers | Unmeasurable | <1.0 ng | <1.0 ng |
| Semipermeable fabrics* | <0.1 L/min | <1.0 ng | <1.0 ng |
| Unwoven synthetics | |||
| Type 1 (Filtrete) | 1.3 L/min | <2.0 ng | 2.3 ng |
| Type 2 (Propore) | 18 L/min | <2.0 ng | 1.5 ng |
| Finely woven fabrics[1] | |||
| 2 micrometers | 8 L/min | <1 ng | 2 ng |
| 6.6 micrometers | 16 L/min | <2 ng | 5.7 ng |
| 10 micrometers | 19 L/min | <2 ng | 78 ng |
| Traditional cotton or synthetic covers | 22 L/min | 133 ng | 580 ng |
