Air Quality


Why is air quality important and how do transportation (mobile) sources affect it? Having clean air is important to both our health and the environment. The cars, trucks, planes, trains, and boats that move people and freight emit pollutants such as carbon dioxide, nitrogen oxides, and fine particles (particulates). To keep these pollutants at a level that protects our health, the Environmental Protection Agency (EPA) has created National Ambient Air Quality Standards (NAAQS). Each county in Kentucky has been designated to have met the NAAQS (attainment) or not (nonattainment). To ensure those levels are not exceeded in the future, we must estimate future pollutant levels using computer models in a process called Transportation Conformity. 

Air Quality Nonattainment or Maintenance Areas

KY Air Quality Designations​

Areas where air pollution levels persistently exceed the standards may be designated as nonattainment. These areas may consist of a county, a partial county or a group of counties. Once the area emissions fall below the standard, the area may be redesignated as "attainment with an approved maintenance plan". For additional explanation of these terms, please see Air Quality Terms and Abbreviations. Further information can be found in the Air Quality FAQ Brochure.


In April 2012, EPA established that the Agency would be vacating the 1997 8-hour ozone standard which had originally designated Boyd, Boone, Bullitt, Campbell, Christian, Jefferson, Kenton and Oldham counties as nonattainment.  Boyd, Bullitt, Christian, Jefferson, and Oldham counties have been redesignated to attainment with an approved maintenance plan under the 1997 8-hour ozone standard.
On July 20, 2012, EPA designated the nonattainment areas for the 2008 8-hour ozone standard (0.075 ppm).  See EPA's 8-hour Designation.  Areas that are designated as nonattainment had a one year grace period.  By which time, on July 20, 2013, a conformity determination for all nonattainment areas was due.  EPA’s implementation of the 2008 Ozone standard changed the state designations. With the 2008 standard, only the partial (northern halves) of Boone, Kenton and Campbell counties are nonattainment.  All other areas within the Commonwealth meet the 2008 8-hour ozone standard.  See Map above.



 Fine Particulate Matter:

In April 2005, EPA designated 6 counties and 1 partial county in Kentucky as nonattainment for the 1997 fine particulate (PM2.5) standard.  Those counties include Boone, Boyd, Bullitt, Campbell, Jefferson, Kenton, and Lawrence (partial).  Since that original designation, Boone, Boyd, Campbell, Kenton and Lawrence (partial) counties have all been redesignated to attainment with an approved maintenance plan.  See map above.

 In December 2012, EPA announced that they were tightening the PM2.5 standard to 12µg/m3.  EPA is due to have designations for the 2012 PM2.5 standard by December 2014.  See EPA's Fine Particulate Matter (PM2.5) Designations.  Further updates will be monitored upon their release from the EPA



 Transportation Conformity:

The State Implementation Plan (SIP) defines the future maximum levels (called budgets) for each pollutant in each nonattainment and maintenance area. Transportation Conformity is a process that uses transportation and air quality models to examine future levels of emissions for each of these areas and ensures that the transportation plan does not worsen or cause air quality problems. Typically, a traffic model is developed based on planned roadway projects to determine projected traffic patterns, volumes, and speeds. These numbers, along with vehicle fleet characteristics and environmental information, are entered into the EPA MOVES 2010b emissions model to determine future emission levels. If the emission levels calculated are less than the budget for that pollutant, the area's long range transportation plan is determined to be "in conformity."

During the planning process, federal, state, and local transportation and environmental agencies consult and come to agreement on the inputs that are entered into the traffic model and MOVES 2010b model. Each time the Long-Range Transportation Plan (LRTP) or the short-range transportation plan, Transportation Improvement Program (TIP), is updated, transportation conformity must be examined. For information on transportation conformity at the federal level see,

Congestion Mitigation and Air Quality (CMAQ)

Federal transportation legislation established the Congestion Mitigation and Air Quality (CMAQ) program to provide funding for projects that improve traffic flow, reduce congestion, and ultimately improve air quality in designated nonattainment or maintenance areas. See Kentucky CMAQ Program for application and program requirements. For federal CMAQ information, see FHWA CMAQ Program.

Air Quality Information

Presentations, Reports, and Brochures

2014 Air Quality Conference Handouts

2014 Air Quality Conference Presentations

Past Air Quality Conference Agendas