From the press release:
In keeping with the president’s memorandum on open government, the U.S. Labor Department’s Occupational Safety and Health Administration is releasing 15 years of data providing details of workplace exposure to toxic chemicals.
The data is comprised of measurements taken by OSHA compliance officers during the course of inspections. It includes exposure levels to hazardous chemicals including asbestos, benzene, beryllium, cadmium, lead, nickel, silica, and others. The data offers insights into the levels of toxic chemicals commonly found in workplaces, as well as insights into how chemical exposure levels to specific chemicals are distributed across industries, geographical areas and time.