The Environmental Protection Agency (EPA) is taking final action to rescind its previously issued clean data determination (CDD) for the Yuma, Arizona "Moderate" nonattainment area (Yuma NAA) for the 1987 24-hour national ambient air quality standard (NAAQS) for particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM<INF>10</INF>) because recent complete, quality-assured monitoring data show that the area has subsequently violated this NAAQS. We are also determining that the Arizona State Implementation Plan (SIP) is substantially inadequate to attain or maintain the PM<INF>10</INF> standard in the Yuma NAA and calling for Arizona to revise the SIP to address this inadequacy.