COMPETING INTERESTS The author has published on respirator issues and has served as an expert witness in law suits pertaining to respirator efficacy. The opinions expressed are solely the author's. REFERENCES 1 (1978). History of respiratory protective devices in the U.S.—Pre World War I. Lawrence Livermore Laboratory, U.S. Energy and Research Administration. 2, , , , , , , & (2005). A survey of private sector respirator use in the United States: An overview of findings.