Below you will find the links to reports, images and explainer text for the independent third parties we have worked with to verify our filtration performance. Cambridge Mask has been tested by Nelson Labs USA with the result of 99.6% viral filtration efficiency and 99.7% bacterial filtration efficiency. During rigorous testing, the mask blocked 99% of particles sized 0.3 microns and up. The Cambridge Mask employs a series of filters designed to ensure only the cleanest possible air. Composed of a total of three layers, each layer acts as a barrier to the various pollutants typically found in both indoor and outdoor air. The three-layered filter system is made up of a Primary Filter, a Three Ply-Micro Particulate Layer, and a Military Grade Activated Carbon Filter.