This action promulgates revisions to ambient air monitoring requirements for criteria pollutants. These revisions include adding and harmonizing definitions; clarifying annual monitoring network plan public notice requirements; revising network design requirements; system modifications and operating schedules; clarifying data certification, data submittal and archiving procedures; reorganizing and clarifying quality assurance requirements; and revising certain network design criteria for non-source oriented lead monitoring. These revisions also address other issues in the Ambient Air Quality Surveillance Requirements, to help reduce the compliance burden of monitoring agencies operating ambient monitoring networks.