Louisiana Designated as Attainment/Unclassifiable for the 2015 Ozone National Ambient Air Quality Standard (NAAQS)


On April 30, 2018, the Environmental Protection Agency (EPA) took the next step in the Clean Air Act (CAA) process to implement the 2015 Ozone NAAQS by designating nearly all the remaining areas.  The EPA touted a reduction in the number of areas of the country designated as nonattainment with the 2015 standard, relying on CAA waivers for emissions associated with natural “background” ozone and “exceptional events” such as wildfires to explain the reduction.

In somewhat of a surprise to some, all areas of Louisiana were designated as attainment/unclassifiable.  This was a big win for the 5 parishes in and around Baton Rouge and was made possible due to the EPA’s 2016 revisions to the 2007 Exceptional Events Rule (EER).

Exceptional events are naturally occurring or unusual episodic events that are not reasonably controllable and that can adversely affect air quality and may inhibit the ability of an area to attain and/or maintain the NAAQS.

On November 8, 2017 Louisiana Department of Environmental Quality (LDEQ) submitted an initial notification to EPA flagging the ozone exceedance episode on September 14th which was believed to be caused by wild fires in the Pacific Northwest. Further investigation and modeling supported the assertion that the regionally elevated ozone measurements and exceedance detected at the Dutchtown monitor was a direct result of the smoke transported from the fires. The information was public noticed on March 1, 2018 as “Exceptional Event Demonstration for Event at Dutchtown Monitor on September 14, 2017.”

Without the EER providing an avenue to identify the elevated ozone measurements recorded by the Dutchtown monitor, this monitored exceedance directly impacted the attainment status of the five parish area.

For more information on the EER and Wildfire/Ozone Implementation Guidance, the EPA developed this PowerPoint.

Background – NAAQS Designations Process

After EPA sets a new NAAQS or revises an existing standard for each criteria air pollutant, the Clean Air Act requires EPA to determine if areas the country meet the new standards.

States and tribes submit recommendations to the EPA as to whether or not an area is attaining the national ambient air quality standards for a criteria pollutant. The states and tribes base these recommendations on air quality data collected from monitors at locations in urban and rural settings as well as other information characterizing air quality such as modeling. After working with the states and tribes and considering the information from air quality monitors, and/or models, EPA will “designate” an area as attainment or nonattainment for the standard.

If the air quality in a geographic area meets or is cleaner than the national standard, it is called an attainment area (designated “unclassifiable/attainment”); areas that don’t meet the national standard are called nonattainment areas.  In some cases, EPA is not able to determine an area’s status after evaluating the available information.  Those areas are designated “unclassifiable.”

Counties and areas classified as nonattainment can face significant challenges in the form of air permitting delays, restrictions on industry expansion within the area, as well as impacts to transportation planning.  These challenges commonly lead to reduced economic development in and around the nonattainment area in addition to greater EPA involvement and oversight in air permitting.

Contributed by Isaac Smith, Environmental Compliance Manager