ACKNOWLEDGMENTS
This manuscript was prepared by a working group of the American Industrial Hygiene Association's Respiratory Protection Committee (RPC). David Abrams was a member of the working group, and his input is acknowledged. The authors would also like to thank the members of the RPC for their thoughtful comments on previous drafts of the manuscript. The findings and conclusions of this article are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health, U.S. Army Institute of Public Health, or the American Industrial Hygiene Association.