Figure 2

Filtration efficiency (FE) of a. KN95 and b. N95-3M masks for different particle sizes (0.3–5 µm) following gamma irradiation (GIR) at either typical (1.65 kGy/h) or low (0.5088 kGy/h) dose rates. Symbols represent the mean and error bars indicate the standard error. Statistically, both masks showed an overall significant (P < 0.001) reduction in FE with increased radiation doses, for both dose rates. Pairwise comparisons for KN95 masks irradiated with typical gamma radiation: particle sizes of 0.3, 0.5, 0.7 and 1 µm versus 2 and 5 µm were significant (P ≤ 0.016); particle sizes of 0.3 and 0.5 µm versus 0.7 and 1 µm were significant (P ≤ 0.002). Pairwise comparison for KN95 masks irradiated with low gamma radiation: 0.3 µm versus 5 µm P = 0.001; 0.5 µm versus 5 µm P = 0.002; 0.7 µm versus 5 µm P = 0.002; 0.3 µm versus 2 µm P = 0.014; 0.5 µm versus 2 µm P = 0.020; 0.7 µm versus 2 µm P = 0.020. Pairwise comparison for N95-3M masks irradiated with typical gamma radiation: particle sizes of 0.3, 0.5, 0.7, 1 and 2 µm vs. 5 µm were significant (P < 0.001); particle sizes of 0.3, 0.5, 0.7 and 1 µm versus 2 µm were significant (P ≤ 0.002); particle sizes of 0.3, 0.5 and 0.7 µm versus 1 µm were significant (P < 0.001); 0.3 and 0.5 µm versus 0.7 µm were significant (P < 0.001); 0.3 µm versus 0.5 µm P < 0.001. Pairwise comparison for N95-3 M masks irradiated with low gamma radiation: particle sizes of 0.3, 0.5, 0.7, 1 and 2 µm versus 5 µm were significant (P < 0.001); particle sizes of 0.3, 0.5, 0.7 and 1 µm versus 2 µm were significant (P ≤ 0.005); particle sizes of 0.3 and 0.5 µm versus 0.7 and 1 µm were significant (P < 0.001).