The U.S. Environmental Protection Agency (EPA) recently designated the entire nation as “unclassifiable/attainment” for the new 2010 nitrogen dioxide (NO2) air quality standards, based on the most recent air monitoring data (2008-2010). However, EPA expects to redesignate areas after it has received three years of data from a new roadside air quality monitoring network, to be in place by 2013.
In 2010, EPA set the one-hour national ambient air quality standard (NAAQS) for nitrogen dioxide at 100 parts per billion (ppb). The agency retained the annual average standard of 53 ppb (see 75 Fed. Reg. 6,474, Feb. 8, 2010). The 2010 rule also established new ambient air monitoring and reporting requirements for NO2, requiring additional monitors near roadways and in urban areas. According to EPA, mobile sources are the largest source of nitrogen oxides emissions.
In a letter to EPA, AGC urged the Agency to remove the monitoring component from its NO2 NAAQS proposal and wait until the new air standard is finalized before proposing a subsequent rule for monitoring requirements. AGC’s comment letter also recommended that EPA consider a pilot study to determine how roadway monitoring of NO2 would function in the real world before imposing this costly new system.
Under EPA’s rule, the new roadside monitoring network must be in place by 2013. EPA plans to make updated attainment designations based on air quality data from the monitors in 2013, 2014, and 2015. The unclassifiable/attainment designations announced Feb. 17 are based on data from 2008, 2009, and 2010 in the current air monitoring system. The data show no violations of air quality standards. See 77 Fed. Reg. 9,532, Feb. 17, 2012.
“Although all existing community-based monitoring sites indicate attainment with the NO2 NAAQS, the existing NO2 monitoring network does not fully portray or represent the NO2 concentrations near roadways,” EPA said in the final rule. Nitrogen dioxide concentrations near major roadways, which will be measured by the new monitors, “are appreciably higher than those measured at monitors in the current network,” the Agency said.
Background
Within two years of setting a new NAAQS or revising an existing standard, the Clean Air Act directs EPA to formally identify or “designate” areas as “unclassifiable/attainment” (meeting the standard or no evidence indicating a violation), “nonattainment” (not meeting the standard), or “unclassifiable” (insufficient information to designate as attainment or nonattainment, but likely to be violating).
To learn more about the designation process for the NO2 standards, and to view individual letters from EPA to states and tribes, go to EPA’s website at www.epa.gov/air/nitrogenoxides/designations/.
For more information, please contact Leah Pilconis at pilconisl@agc.org.