The Nonattainment Area - Particulate Matter-2.5 Annual (1997) dataset was designated on April 05, 2005 by the Environmental Protection Agency (EPA) and is part of the U.S. Department of Transportation (USDOT)/Bureau of Transportation Statistics (BTS) National Transportation Atlas Database (NTAD). This dataset provides detailed information about areas identified in the U.S. where annual particulate matter (PM2.5) levels have not met the National Ambient Air Quality Standards (NAAQS) established in 1997 for particulate matter (PM2.5) and have been designated "nonattainment areas (NAA)". The 1997 Primary Annual PM-2.5 NAAQS is revoked in attainment and maintenance areas for that NAAQS. For additional information see the PM-2.5 NAAQS SIP Requirements Final Rule, effective October 24, 2016 (https://www.govinfo.gov/link/fr/81/58009). These data are weekly from an OAQPS internal database. However, that does not necessarily mean the data have changed. For more information about this non-attainment area, please see the website https://www.epa.gov/green-book/green-book-pm-25-1997-area-information. A data dictionary, or other source of attribute information, is accessible at https://doi.org/10.21949/1529068