Question: how effective are dust masks?
Answer: The protective efficiencies were 33.3%, 11.3%, and 6.1% for the surgi- cal, bandana, and dust masks, respectively. The N95 mask protective efficiency was 89.6%. ... The mean aerosol concentration of a moderate dust storm is 0.040 mg/L, and the particle size is less than or equal to 2.5 ƫm (Chan, 2002; Selinus, 2005).