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Revisions to the Federal Lead Ambient Air Quality Monitoring Requirements

Most Recent Action


Final revisions were released on December 14, 2010, and the effective start date was January 26, 2011.




The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for “criteria pollutants.” Currently, lead, ozone, nitrogen oxides, carbon monoxide, sulfur oxides, and particulate matter are listed as criteria pollutants. The law also requires EPA to periodically review the standards to ensure that they provide adequate health and environmental protection, and to update those standards as necessary. The latest update was issued in a final rule by the EPA on November 12, 2008.


In January 2009, the Missouri Coalition for the Environment Foundation, the Natural Resources Defense Council, the Physicians for Social Responsibility, and the Coalition to End Childhood Lead Poisoning petitioned for a reconsideration of the lead emission rate at which monitoring is required. On July 22, 2009, the EPA granted the petition to reconsideraspects of the monitoring requirements.


In response to the petition, the EPA reviewed and reconsidered the monitoring requirements proposed revisions to the requirements for both source-oriented and non-source-oriented monitoring for lead. The revised standards are 10 times stricter than the previous standards.




Two sections of the Clean Air Act (Act) govern the establishment and revision of the NAAQS.


Section 108 (42 U.S.C. 7408) directs the Administrator to identify and list each air pollutant that ‘‘in his judgment, cause or contribute to air pollution which may reasonably be anticipated to endanger public health and welfare’’ and whose ‘‘presence…in the ambient air results from numerous or diverse mobile or stationary sources’’ and to issue air quality criteria for those that are listed.


Section 109 (42 U.S.C. 7409) directs the Administrator to propose and promulgate ‘‘primary’’ and ‘‘secondary’’ NAAQS for pollutants listed under section 108. Section 109(b)(1) defines a primary standard as one ‘‘the attainment and maintenance of which in the judgment of the Administrator, based on [air quality] criteria and allowing an adequate margin of safety, are requisite to protect the public health.’’ A secondary standard, as defined in Section 109(b)(2), must ‘‘specify a level of air quality the attainment and maintenance of which, in the judgment of the Administrator, based on criteria, is requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of [the] pollutant in the ambient air.’’


Section 307(d)(7)(B) of the Clean Air Act (42 U.S.C. 7607) allows petitions objecting to rules if the person raising an objection can demonstrate to the Administrator that it was impracticable to raise such objection within the time for comments, or if the grounds for objection arose after the period for comments closed. If the objection is also of central relevance to the outcome of the rule, the Administrator shall reconsider the rule.




The revised lead emissions monitoring threshold is 0.50 tons per year (tpy), an increase from 1.0 tpy. There are three lead emissions sources in Wisconsin emitting between 0.50 and 1.0 tpy. Monitoring agencies will be required to conduct monitoring near lead sources that emit 0.50 tpy or greater, or request a waiver as allowed by 40 CFR part 58, Appendix D, paragraph 4.5(a)(ii).


The rule was finalized on December 14, 2010, so source-oriented monitors will begin operating in December 2011.  Monitors around the largest sources, those that that emit 1.0 tpy or greater, were already required to be operational by January 1, 2010.


Fuel used for piston-engine aircraft still contains lead. As a result, the EPA is going to treat airports identically to other sources of lead when determining if source-oriented lead monitoring is needed. The EPA identified 55 airports that may exceed the proposed 0.50 tpy emission threshold. State and local monitoring agencies will be required to monitor these airports, request a waiver as allowed under 40 CFR part 58 Appendix D, or demonstrate that the actual emissions from a given airport are less than 0.50 tpy.


As part of the November 2008 revisions to the lead NAAQS, the EPA required one lead monitor site in each Core Based Statistical Area (CBSA) with a population of 500,000 people or more—leading to 101 monitors. The revised rule will instead require lead monitoring at sites comprising the NCore Network.


The NCore Network is intended to be a long-term, multi-pollutant, monitoring network that not only provides information useful to NAAQS attainment decisions, but also provides data needed to broaden the understanding of air quality conditions and pollutant interactions, evaluate air quality models, develop emission control strategies, and support long-term health studies. The NCore Network will consist of approximately 80 sites—60 sites located in urban areas and about 20 sites in rural areas. The Mayville site in Dodge County is one of the rural sites. The EPA required monitoring agencies to commence lead sampling at NCore sites no later than January 1, 2011.


The EPA estimates these changes will collectively expand the existing lead monitoring network by approximately 140 sites. The proposal would modify the 2008 requirements for the lead monitoring network by requiring 160 additional monitors near sources of airborne lead and requiring 80 additional monitors at NCore stations instead of 100 monitors in CBSA’s with a population of 500,000 or more.


Proposed Standards Related Documents


Fact Sheet, December 2010


Final Revisions, December 14, 2010


Proposed Rule, Federal Register, December 30, 2009


Fact Sheet


Letter to petitioners granting reconsideration, July 22, 2009


Petition for reconsideration, January 12, 2009


2008 final rule being reconsidered, November 12, 2008


The EPA’s Lead Standards’ webpage


Locations of Lead Emission Sources


Implementation of the 2008 Standards


Although they are being reconsidered, the November 2008 rules are currently being implemented.


In the first round of designation, the EPA used data from currently operating monitors, with a goal of designating nonattainment areas by October 2010. On June 15, 2010 the EPA’s regional administrators sent letters to governors of all states and territories notifying them of their current status. The EPA notified twelve states that they have at least one area under consideration for a nonattainment designation based on the 2008 lead standards. States and tribes may comment on the plans outlined in the letters, and provide additional information to EPA by August 16, 2010.  The public may also review the agency’s plans and provide comment through August16, 2010.


The 2008 rules also established requirements for siting new lead air monitors that took effect on January 1, 2010. The EPA intends to make a second round of final designations in October 2011 using information from the new monitors. States and tribes may provide updated recommendations for the second round of designations by December 15, 2010.


The Wisconsin DNR recommended that the entire state be designated as in attainment of the revised NAAQS for lead in the first round of designations. However, the EPA is waiting to designate Wisconsin until the second round.


Implementation of 2008 Standards Related Documents


Map of the EPA’s Response to State Recommendations on 2008 Lead Designations, June 15, 2010


The EPA’s letter responding the Wisconsin’s first round designation recommendation, June 15, 2010


Letter outlining Wisconsin’s current lead monitoring network, August 11, 2009


2008 final rule being reconsidered and implemented, November 12, 2008