Table 2. Definitions and standards of detection indicators.

Detection indicator	Definition	Eligibility criteria
Pressure difference /Pa	The resistance of mask with the specified area and specified flow	≤49
Particle filtration efficiency /%	Under specified test conditions, the filter element filters out the percentage of particulate matter	≥30
Bacterial filtration efficiency /%	Percentage filtration of bacteria-containing suspended particles by mask material at a specified flow rate	≥95
Resistance to surface wetting	The resistance of fabrics to wetting or penetration by water, measured by the spray rating	≥3