TABLE. III.
Combined face coverings and plastic shield acoustic attenuation RMS results in dB between 2 and 8 kHz relative to no mask condition.
| No Shield | With Shield | ||||
|---|---|---|---|---|---|
| Material | 3 ft | 6 ft | 3 ft | 6 ft | |
| III.1 | Polypropylene ASTM Level 2 (MediCom 2142) | 3.6 | 3.5 | 19.5 | 18.1 |
| III.2 | Polypropylene ASTM Level 3 (DemeTECH) | 4.2 | 4.2 | 19.9 | 18.0 |
| III.3 | KN95 respirator (Huixin GB-2626-2006) | 6.3 | 6.3 | 20.0 | 19.5 |
| III.4 | N95 respirator (3 M 8511) | 6.4 | 6.2 | 23.0 | 21.4 |
| III.5 | PM2.5 (Tworux) | 8.4 | 8.0 | 23.5 | 22.4 |
| III.6 | Cloth (handmade) | 5.4 | 5.1 | 20.5 | 18.3 |
| III.7 | Cloth with HEPA filter (handmade) | 6.1 | 5.7 | 22.1 | 20.2 |
| III.8 | The Communicator (Safe ‘N’ Clear) | 9.0 | 8.5 | 22.5 | 22.3 |
| III.9 | FaceView (Jeanne Hahne) | 9.8 | 9.4 | 23.6 | 22.2 |
| III.10 | Cotton/polyester blend and vinyl window 1 (handmade) | 14.2 | 13.0 | 25.0 | 23.6 |
| III.11 | Cotton/polyester blend and vinyl window 2 (handmade)a | 14.5 | 13.4 | 25.0 | 24.6 |
| III.12 | III.1 (Polypropylene 1) and III.4 (N95) doubled up | 9.3 | 9.0 | 25.7 | 24.9 |