An official website of the United States government.
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.
The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.
From American Conference of Governmental Industrial Hygienists (ACGIH®), Date: 1-91, Figure VS-50-21, Industrial Ventilation : A Manual of Recommended Practice, 23rd Edition. Copyright 1998. Reprinted with permission.
