The "95" in "N95" refers to their 95% efficiency at filtering particles of the size they are least efficient at (.3 microns IIRC). They are more effective at si

The "95" in "N95" refers to their 95% efficiency at filtering particles of the size they are least efficient at (.3 microns IIRC). They are more effective at sizes larger and smaller. The smaller particles get stuck to the mask via static electricity.