A structure for trapping hazardous dust in a work place which also serves as a walkway is disclosed. A removable cover member (12) includes a frame and a central support member (18), the frame and central support member (18) being covered with expanded metal mesh (22). The cover rests upon a shallow pan (10), the pan (10) having a raised central ridge (28) which is aligned with the central support member (18) in the cover (12) when the cover (12) is placed on the pan (10). The central support member (18) and the central raised ridge (28) cooporate to limit the deflection of the expanded metal mesh (22) under the weight of a user. The lower pan (10) is provided with a hook (34), for engaging other similar pans (10) for assembling a walkway or other desired configuration of dust collecting pans. The pan may be filled with a non-evaporating liquid to permanentaly retain dust falling into the pan, and also dust being scraped from the shoes of a user by the expanded metal mesh.