Air Quality Division: Plans: Nitrogen Dioxide (NO2)

Revised National Ambient Air Quality Standard (NAAQS) for Nitrogen Dioxide (NO2)

After a public process period ending in a public hearing held on January 04, 2011, boundary recommendations were submitted by Governor Brewer to U.S. EPA Region 9 on January 25, 2011. Arizona's recommendation was that each county be designated "unclassifiable" for NO2. This was based on insufficient monitoring data for areas with high volume highway traffic. U.S. EPA guidance released on November 11, 2010, indicated that there is no need to complete a traditional factor analysis for this revised standard. On June 29, 2011, U.S. EPA informed states that they would be changing recommendations from "unclassifiable" to "attainment/unclassifiable." Arizona does not object to this change in classification.

For more information, please contact us.