We conducted a survey of mask in the inventory of major academic medical centers in Boston, MA to determine provenance and manufacturer. We performed tests of filtration performance at an academic lab and tested masks from the inventory. Based on these results, and in consultation with occupational health officers, we make six recommendations for end users to assist in acquiring legitimate products. More information available at this preprint.
Detailed information on how to build and use the mask filtration testing apparatus, as well as results generated using such a setup, can be found at cleanmask.org.