Update on 2008 Ozone NAAQS Implementation



The 2008 Ozone National Ambient Air Quality Standards(NAAQS) - both the primary and secondary standards were promulgated on March 12, 2008 and became effective on May 27, 2008. The 8-hr ozone NAAQS was set in 2008 at a level of 0.075 ppm. Once a NAAQS is promulgated for a criteria pollutant, area designations need to be assigned; and this occurred by July 20, 2012 for this ozone standard. A full list of Nonattainment Areas can be found on the United States Environmental Protection Agency's (USEPA) Green Book Nonattainment Areas for Criteria Pollutant.

The USEPA published a final rule on March 6, 2015, regarding the "Implementation of the 2008 National Ambient Air Quality Standards for Ozone: State Implementation Plan Requirements". This rule addresses a range of nonattainment area state implementation plan (SIP) requirements for 2008 ozone NAAQS, including those requirements which pertain to demonstrating attainment, reasonably available control technology (RACT), reasonably available control measures (RACM), reasonable further progress (RFP), major new source review (NSR), emission inventories and emission control measures in the SIP submissions as well as compliance with emission control measures in the SIP.

The marginal non-attainment areas have three (3) years from the date of last designation (i.e., July 20, 2015) to show attainment with the 2008 8-hr ozone NAAQS. The attainment status is determined based on the ozone monitoring data from 2012 to 2014. If the monitoring data (over the reviewed time period) is threatening the area designations, per the provisions of the Clean Air Act (CAA), a state can request for a 1 to 2 year extension for showing attainment if the existing monitoring data meets certain criteria. The criteria includes that the 4th highest daily maximum 8-hr average in the attainment year is 0.075 ppm or less. Even after the added leeway in the CAA, it is possible that an area's monitoring data is not favorable for this extension; and the areas non-attainment designation could be affected (e.g., serious non-attainment for 8-hr ozone NAAQS from Moderate per the requirements of the CAA). However, the affected area may be able to demonstrate attainment, if the 2013-2015 monitoring data meets the criteria for an attainment per the provisions of the CAA.

The rule also discusses the revoking of the 1997 ozone 8-hr standard (effective April 6, 2015);and the applicable anti-back sliding requirements that apply when the rule is revoked. Anti-backsliding requirements are for retaining and preserving the air quality improvements that were achieved under the previous NAAQS. If the primary or secondary ozone NAAQS are revised in the future, the USEPA expects that this rule shall help facilitate implementation of any new standards.