On This Day:  August 5

1963 -- World nu­cle­ar pow­ers sign the Par­tial Nu­cle­ar Test Ban Treaty, which pro­hibits the sig­na­to­ry na­tions from det­o­nat­ing atom­ic bombs or spread­ing ra­dioac­tive pol­lu­tion on any­one but their own cit­i­zens.