History of U.S. Respirator Approval.

This article is the second in a series of four articles on respirator history. The discussions presented in this article follow the history of respirator requirements, use, improvements, and certification in America. Included is a discussion of respirator evolution prior to American certification standards and discussion of the need, primarily from the mining industry, for government respirator certification. The reasons for government intervention and the origination of the American respirator certification program are discussed.