<sod>According to tests at Sandia, the Gravel Gertie successfully reduced the expected level of external airborne contamination by a factor of 10, which was considered satisfactory to limit exposure to the immediate area.<ref>Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons Since 1940. ed. Steven Schwartz. Brookings Institution Press, 1999. ISBN 9780815722946pp. pp. 49-51.</ref> The bunkers were installed at all US and British facilities that performed warhead arming and de-arming.<eod>
<sod>According to tests at Sandia, the Gravel Gertie successfully reduced the expected level of external airborne contamination by a factor of 10, which was considered satisfactory to limit exposure to the immediate area.<ref>Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons Since 1940. ed. Steven Schwartz. Brookings Institution Press, 1999. ISBN 978-0815722946 pp. 49-51.</ref> The bunkers were installed at all US and British facilities that performed warhead arming and de-arming.<eod>