The filter material in the Sportsta mask is subject to testing which gives 99% filtration of particulates smaller than PM2.5 (2.5 microns); in fact almost ten times smaller, 0.3 microns. An important point with respect to masks is how well they fit. If they fit poorly then the air will just pass through the gap where it doesn’t fit, that’s why we have three sizes. To find out what size you are visit our sizing guide.