National Ambient Air Quality Standard (NAAQS) for lead is a rolling three-month average of 0.15 µg/m3. The new standard, which became effective on January 12, 2009, represents a dramatic decrease from the prior standard of 1.5 µg/m3, measured as a quarterly average. The Federal Register Notice of the final rule is available.
Monitoring and designation
When a new standard is promulgated, states must determine if they attain the standard. The state usually does this through reviewing monitoring data. The state must then make a recommendation to EPA on whether all or part of the state should be designated as meeting the standard (attainment), not meeting the standard (nonattainment) or if insufficient data exists to make a recommendation (unclassifiable).
MPCA submitted a designation recommendation to EPA in October 2009, based on existing monitoring data. The MPCA recommended a nonattainment designation for an area surrounding Gopher Resource Corporation in Eagan, Dakota County. Gopher Resource is a lead smelter and battery recycler.
The area was previously a maintenance area for the prior lead standard. The designation recommendation was based on data from 2007 through 2009. You can view the official state designation recommendations, and EPA responses, for Minnesota and other states in Region 5.
In November 2010, EPA officially designated the MPCA’s recommended area of Dakota County as a nonattainment area. The official geographic designation of the nonattainment area is: A portion of the city of Eagan bounded by Lone Oak Road (County Road 26) to the north, County Road 63 to the east, Westcott Road to the south, and Lexington Avenue (County Road 43) to the west. The nonattainment area designation became effective on December 31, 2010.
EPA has published a full list of the 16 areas nationally that were designated as being in nonattainment with the new standard. EPA’s Lead Designation Table.
In addition, EPA required additional ambient air quality monitoring near sources that emit more than 0.5 tons per year of lead. The MPCA did not make any additional nonattainment designation recommendations based on this additional monitoring, as all new monitors are showing compliance with the standard.
More information on lead monitoring can be found by reviewing the 2011 Source-oriented Lead Monitoring Plan for Minnesota and Air Monitoring Network Plan.
The MPCA submitted a State Implementation Plan (SIP) for the nonattainment area in Eagan in June 2012. The MPCA has been working with Gopher Resource to ensure controls are in place that will allow the area to attain the new lead standard. The SIP requires some new controls and provides a demonstration that the standard can be attained by the required date of December 2015. Recent monitoring has shown ambient lead levels that are below the revised standard. Three years of data meeting the standard is necessary before an area can be redesignated to attainment.