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Lead in Air

Fact Sheet - Revisions to Lead Ambient Air Monitoring Requirements


  • On December 23, 2009 the Environmental Protection Agency (EPA) proposed to revise the ambient monitoring requirements for measuring airborne lead.  These rule amendments would improve the lead monitoring network to better assess compliance with the revised National Ambient Air Quality Standards (NAAQS) established in November 2008.  The revised standards are 10 times tighter than the previous standards and will improve health protection for at-risk groups, especially children.
  • EPA is proposing to change the lead emissions monitoring threshold to 0.50 tons per year (tpy). Air quality monitoring agencies would use this threshold to determine if an air quality monitor is required to be placed near a facility emitting lead.  EPA also is requesting comments on alternative emission thresholds.  The current emissions threshold is 1.0 tpy. 
  • EPA proposes that these source-oriented monitors would begin operating one year after this rule is finalized.  Monitors around the largest sources (those that that emit 1.0 tpy or greater) are already required to be operational no later than January 1, 2010.
  • EPA is also proposing to require lead monitoring at sites comprising the “NCore Network” instead of the current requirement to place lead monitors in each Core Based Statistical Area (CBSA) with a population of 500,000 or more people.  Under this proposal, lead monitoring at NCore sites would begin January 1, 2011.
  • The NCore network is intended to be a long-term, multi-pollutant monitoring network that provides data useful for NAAQS attainment decisions, understanding of air quality conditions and pollutant interactions, evaluating air quality models, developing emission control strategies, and supporting long-term health studies.  The NCore network will become fully operational no later than January 1, 2011 and will consist of approximately 80 sites—  60 sites located in urban areas and about 20 sites in rural areas.  
  • Fuel used for piston-engine aircraft still contains lead.  (Commercial aircraft do not use leaded fuel.)  As a result, EPA is proposing to treat airports identically to other sources of lead when determining if source-oriented lead monitoring is needed.  The Agency is requesting comments on the availability of data that may be useful in setting an alternative emission threshold for airports.
  • EPA estimates these proposed changes would 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
    • requiring 80 additional monitors at NCore stations
    • no longer requiring approximately 100 monitors in CBSA’s with a population of 500,000 or more


  • The lead monitoring network measures concentrations of lead in the outdoor air, to assess compliance with the lead national ambient air quality standards (NAAQS).
  • EPA substantially strengthened those standards in a rule issued Oct. 15, 2008, revising the level of the primary (health-based) standard from 1.5 micrograms per cubic meter (μg/m3) to 0.15 μg/m3, measured as total suspended particles (TSP). The agency revised the secondary (welfare-based) standard to be identical to the primary standard.
  • In January 2009, EPA received a petition to reconsider the lead monitoring requirements from the Missouri Coalition for the Environment Foundation, Natural Resources Defense Council, the Coalition to End Childhood Lead Poisoning, and Physicians for Social Responsibility.
  • EPA granted the petition to reconsider on July 22, 2009.  This proposal represents the results of the EPA’s reconsideration of the lead monitoring requirements.
  • The reconsideration will not change the timeline for meeting the revised lead standards or the deadline for deploying monitors around sources that emit at least 1.0 tons per year of lead.


  • EPA will accept comment on the proposal for 45 days after publication in the Federal Register. Comments, identified by Docket ID No. EPA-HQ-OAR-2006-0735, may be submitted by one of the following methods:
    • www.regulations.gov: follow the on-line instructions for submitting comments.
    • E-mail: Comments may be sent by electronic mail (e-mail) to a-and-r-Docket@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2006-0735.
    • Fax: Fax your comments to: 202-566-1741, Attention Docket ID. No. EPA-HQ-OAR-2006-0735.
    • Mail: Send your comments to: Air and Radiation Docket and Information Center, Environmental Protection Agency, Mail Code: 6102T, 1200 Pennsylvania Ave., NW, Washington, DC, 20460, Attention Docket ID No. EPA-HQ-OAR-2006-0735.
    • Hand Delivery or Courier: Deliver your comments to: EPA Docket Center, 1301 Constitution Ave., NW, Room 3334, Washington, D.C. Such deliveries are only accepted during the Docket’s normal hours of operation, and special arrangements should be made for deliveries of boxed information.


  • Today’s proposed rule and other background information are also available either electronically at www.regulations.gov, EPA’s electronic public docket and comment system, or in hardcopy at the EPA Docket Center’s Public Reading Room.
    • The Public Reading Room is located in the EPA Headquarters , Room Number 3334 in the EPA West Building, located at 1301 Constitution Avenue, NW, Washington, DC. Hours of operation are 8:30 a.m. to 4:30 p.m. eastern standard time, Monday through Friday, excluding Federal holidays.
    • Visitors are required to show photographic identification, pass through a metal detector, and sign the EPA visitor log. All visitor materials will be processed through an X-ray machine as well. Visitors will be provided a badge that must be visible at all times.
    • Materials for this proposed action can be accessed using Docket ID No. EPA-HQ-OAR-2006-0735.
  • For more information about Pb in the air, and the recent NAAQS revision, go to EPA’s web site at: www.epa.gov/air/lead/.
  • For more information about today’s rulemaking, contact Kevin Cavender at EPA’s Office of Air Quality Planning and Standards at (919) 541-2364 or cavender.kevin@epa.gov.

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