N95 facemasks have several historical predecessors. One was a design for a cloth facemask by Lien-teh Wu, who was working for the Chinese Imperial Court in the fall of 1910 during the Manchurian plague outbreak.[38] It was the first that protected users from bacteria in empirical testing, and inspired masks used during the 1918 flu pandemic.[39] Another predecessor was gas masks developed during World War I, which were adapted for use by miners. They were reusable but bulky and uncomfortable due to their fiberglass filters and heavy rubber construction.[3][39]