Table II.
Decontamination methods and summary of results by outcome [21].
| Test agent and conditions | Intervention | Mask/component | Findings | Comments |
|---|---|---|---|---|
| Filtration efficiencya | FE% (absolute difference from control) | |||
| Charge neutralized polydispersed potassium sodium tartrate tetrahydrate droplets (results for 0.1 μm particle diameter). 5.95 L/min flow rate over mask pieces (stated to be equivalent to 85 L/min on full mask) |
Dry heat | Gauze | 85.6 (–1.3) | Dry heat caused the least reduction in FE; P-values not reported for this particle size |
| Spunlace | 40.6 (–4.3) | |||
| Autoclave | Gauze | 74.2 (–12.8) | ||
| Spunlace | 43.7 (–12.1) | |||
| Ethanol | Gauze | 70.5 (–16.5) | ||
| Spunlace | 31.0 (–13.8) | |||
| Isopropanol | Gauze | 50.8 (–36.1) | ||
| Spunlace | Not reported | |||
| Bleach | Gauze | Not assessable (mask destroyed) | ||
| Spunlace | 29.6 (–15.3) | |||
| Airflow resistanceb | Pressure reduction in mmH2O (absolute difference from control) | |||
| Applied: 5.95 L/min flow rate over mask pieces (stated to be equivalent to 85 L/min on full mask) | Dry heat | Gauze | 3.9 (+0.1), NS | No significant changes in airflow resistance following dry heat and ethanol decontamination (gauze mask only) |
| Spunlace | 1.4 (+0.1), P < 0.05 | |||
| Autoclave | Gauze | 3.1 (–0.7), P < 0.05 | ||
| Spunlace | 1.6 (+0.3), P < 0.05 | |||
| Ethanol | Gauze | 3.9 (+0.2), NS | ||
| Spunlace | 1.7 (+0.4), P < 0.05 | |||
| Isopropanol | Gauze | Not reported | ||
| Spunlace | Not reported | |||
| Bleach | Gauze | Not assessable (mask destroyed) | ||
| Spunlace | 1.6 (+0.3), P < 0.05 |
FE, filtration efficiency; NS, not statistically significant.
a
FE to testing agent used, expressed as a percentage. A higher percentage filtration efficiency indicates better mask performance. Results in study were presented as percentage particle penetration, and converted to filtration efficiency (FE % = 100 – particle penetration) for consistency of reporting in this systematic review.
b
Airflow resistance assessed the ‘breathability’ of the mask at tidal breathing. A lower airflow resistance means better breathability.