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The New NAAQS for Lead – 30 Years Later, 10% of the Original Rule

Posted: January 16th, 2012

Author: All4 Staff 

The United States Environmental Protection Agency (U.S. EPA) has announced final rules that substantially strengthen the National Ambient Air Quality Standards (NAAQS) for lead (Pb).  U.S. EPA’s action marks the first time that the Pb standards have been changed in 30 years.  Citing a dramatic expansion of scientific evidence about the health impacts since the initial lead standards were set 30 years ago, U.S. EPA is revising both the primary (health-based) and secondary (welfare-based) standards to levels that are 10 times more stringent than the previous standards.  The final rule revising the Pb NAAQS is effective on January 12, 2009.  Areas that are classified as not attaining the revised Pb NAAQS will have until January 2017 to achieve attainment status.

What has U.S. EPA Changed?

The changes to the Pb NAAQS include revisions to the actual standards as well as changes to guidance and procedures for their implementation.

The Standards

The Pb NAAQS is defined by four (4) elements – level, indicator, averaging time, and form.

  • The level (or standard) of the previous primary (health-based) and secondary (welfare-based) standards, set in 1978, were each 1.5 µg/m3.  The primary and secondary standards have been reduced to a level of 0.15 µg/m3.
  • The indicator defines the measurement basis to determine attainment of the standards.  For the new standard, the indicator that was established in 1978 (Pb in total suspended particulate (Pb-TSP)) has been retained.  However, U.S. EPA is also providing that sampling data for Pb in particulate matter less than or equal to 10 µm in diameter (Pb-PM10) can be used in conjunction with the revised Pb NAAQS under certain limited circumstances and under certain conditions.  Such data may be allowed for measurements at non-source-oriented locations where ultra-coarse particles are not expected to be present and the Pb concentrations are expected to be well below the standard.
  • Averaging time refers to the time period over which monitoring results are averaged in order to develop values to compare to the standards. Form defines how the averaged values are evaluated to determine attainment of the standards.  The averaging time and form for the previous standards were a maximum (not-to-be-exceeded) arithmetic average of all valid samples that were collected during each calendar quarter.  The averaging time and form for the new Pb NAAQS is a maximum (not-to-be-exceeded) 3-month rolling average that is evaluated over a 3-year period.  The revised calculation method considers each rolling 3-month period in a given year (e.g., February – April, March – May, etc.), not just the four (4) calendar quarters.

Determinations of whether an area is in compliance with the new Pb NAAQS will be made according to the following steps:

  • Sampling results from each consecutive rolling 3-month period will be averaged together.  For each 3-year period, this will yield 36 3-month averages.
  • Each of the 36 3-month averages will be compared to the NAAQS.
  • To be in attainment, all 36 3-month averages must be equal to or less than 0.15 µg/m3.
  • The area is considered nonattainment if one (1) of these averages is greater than 0.15 µg/m3.

Are There Any Other Changes to the Standards?

Yes – in addition to changing the level, averaging time, and form of the standard, U.S. EPA has made the following changes and additions to the standards.

40 CFR Part 50, Appendix R

Appendix R (Interpretation of the National Ambient Air Quality Standards for Pb), has been added to 40 CFR Part 50.  Appendix R specifies the data handling procedures for the revised standards, as well as the calculations necessary for determining when the new Pb NAAQS is met.  Appendix R also addresses data reporting, sampling frequency, and data completeness considerations.

Ambient Air Monitoring and Reporting

Ambient Pb monitoring data are collected and reported by state and local agencies in accordance with the requirements in 40 CFR Parts 50, 53, and 58.  The new Pb NAAQS rulemaking finalizes changes to the Pb monitoring regulations within these rules.

New ambient monitoring network design requirements have been established to ensure adequate assessment of compliance with the tightened Pb standards.  Agencies are now required to conduct ambient air Pb monitoring that accounts for Pb sources.  At a minimum, there must be one (1) monitor placed to measure the maximum Pb concentration resulting from each source that emits one (1) ton or more of Pb per year based on the most recent National Emission Inventory (NEI) (or other justifiable methods and data such as improved emission factors or site-specific data).  U.S. EPA Regional Administrators may approve waivers of this source-oriented monitoring requirement for sites where the monitoring agency demonstrates that the emissions will not contribute to Pb-TSP concentrations greater than 50% of the new standard, based on monitoring data or other means.  In addition to the source-oriented monitoring, agencies must locate at least one (1) monitor in each urban area with a population greater than 500,000.

What is the Timeline for Implementing the New Standards?

States are primarily responsible for achieving and maintaining compliance with the NAAQS after U.S. EPA has set them.  States are required to submit recommendations for area attainment designations by October 2009.  U.S. EPA will make final attainment designations no later than January 2012.

States will deploy new monitors to comply with the new network design requirements.  Approximately half of the newly required Pb monitors must be operational by January 1, 2010, with the other half operational by January 1, 2011.  States must also develop State Implementation Plans (SIPs) to establish control programs that will largely be directed at stationary sources of Pb.  States must submit their SIPs to U.S. EPA by June 2013. Each SIP will need to describe how the state will achieve and maintain compliance with the new Pb standards.  Attainment of the new Pb NAAQS must be achieved no later than January 2017.

The 1978 Pb NAAQS will be retained until one (1) year after designations for the new standards, except in current nonattainment areas.  In these areas, U.S. EPA will retain the 1978 standard until the area submits, and U.S. EPA approves, attainment or maintenance demonstrations for the new standards.

How Will Sources Be Affected?

The revision to the Pb NAAQS has the potential to impact many facilities that were not previously associated with ambient Pb concentrations.  Based on U.S. EPA’s 2002 NEI, stationary source sectors of Pb emissions include not only the Pb smelting and metal mining industries, but also iron and steel foundries, glass and cement manufacturing plants, waste incinerators, and industrial/commercial/utility boilers.

Certain areas that have been in compliance with the 1978 standards may now be designated as nonattainment.  Currently only two (2) areas in the U.S. are designated as nonattainment with the 1978 Pb NAAQS.  Based on the most recent data available from the existing monitoring network, an additional 18 areas would violate the new standards.  However, U.S. EPA will be making designations based on data from the new expanded Pb monitoring network, which U.S. EPA estimates that 236 new or relocated monitoring sites will be necessary.  This expanded monitoring network could identify additional nonattainment areas. As a result, the revised Pb NAAQS may directly impact stationary sources in the following ways:

  • New Monitors:  States will be placing new Pb monitors in close proximity to stationary sources for which the most recent NEI shows emissions of one (1) or more tons of Pb per year.  Should the results from such a monitor indicate a violation of the new Pb NAAQS, the facility will be identified as the source of the violation and will become subject to additional control programs established in SIPs.
  • Reasonable Available Control Measures: Any state containing an area designated as nonattainment with respect to the new Pb NAAQS must develop a SIP meeting the requirements of Part D, Title I, of the Clean Air Act (CAA).  SIPs that are submitted to meet Part D requirements must, among other things, include Reasonably Available Control Measures (RACM) that address stationary sources of Pb.  U.S. EPA’s guidance for implementing the previous Pb NAAQS recommended that stationary sources that emit a total of five (5) tons per year or more of Pb (or Pb compounds) be the minimum starting point for requiring Reasonably Available Control Technology (RACT).  In setting the new Pb NAAQS, U.S. EPA has now set the recommended threshold for RACT at 0.5 tons per year or more of Pb.  Therefore, facilities that were not previously subject to RACT for Pb may now become subject to additional controls associated with RACM.
  • Permitting: Pb emissions may become more prominent during air quality preconstruction review and permitting of new and modified stationary sources.  Such programs include Prevention of Significant Deterioration (PSD), Nonattainment New Source Review (NNSR), and Minor New Source Review; all of which are collectively referred to as New Source Review (NSR) programs.  The current significant emission increase level for Pb emissions at existing major stationary sources is 0.6 tons per year.  If the significance level for Pb is lowered to a level that is commensurate with the new NAAQS, then many more modifications at major stationary sources could trigger NSR for modifications that result in small Pb emission increases. When NSR is triggered, additional requirements could include, but are not limited to, the following:
    • Determinations and installation of Best Available Control Technology (BACT) or Lowest Achievable Emissions Rate (LAER) control technology.
    • Ambient air quality impact analyses to demonstrate that the project will not cause a violation of the NAAQS.
    • Notification to Federal Land Managers.
    • Offsetting of new emissions with creditable emissions reductions.
    • Alternative siting analysis to demonstrate that the benefits of the project significantly outweigh the environmental and social cost of the new or modified source.
    • Public notice, comment, and the potential for a public hearing.

What Will This Cost?

The CAA does not allow U.S. EPA to consider costs in setting or revising NAAQS.  Nevertheless, U.S. EPA is required by executive order to analyze the costs of meeting the standards.  U.S. EPA’s analysis indicates that some areas will not reach attainment through application of currently existing and available control technologies.  Therefore, to estimate the costs of meeting the new Pb NAAQS, U.S. EPA analyzed the use of both existing controls and controls that might be developed in the future to reduce Pb emissions from sources.  U.S. EPA has estimated that the cost  to implement known control technologies is approximately $150 million, but the cost to implement the currently unknown source control technologies that will be needed to achieve full attainment could be as much as $2.8 billion.

What Should I Be Doing?

While it is the states that are required to initiate activities during the next year or so, there are steps that Pb-emitting facilities can take now to anticipate and manage the impacts of the revised Pb NAAQS:

  1. Develop and maintain a detailed Pb emission inventory for your facility based on the most recently available emission factors, test data, and operating information.
  2. Check the most recent NEI database to confirm that Pb emissions listed from your facility are consistent with what you had reported and submit corrections if necessary.
  3. Monitor and participate in the activities of your state or local air agency related to the revised Pb NAAQS.
  4. Identify information that could be used to demonstrate your facility’s minimal contribution to Pb-TSP concentrations (e.g., emissions, ambient Pb-TSP, and meteorological data for modeling) and consider beginning to collect this information now.


The revision to the Pb NAAQS represents a significant rule change with the potential to impact many facilities that were not previously associated with Pb emissions.  It will require such facilities to have a more detailed inventory of Pb emissions based on the most recent information available.  The rule may have a major impact on Pb-emitting facilities that are located in states containing areas that will be newly designated as nonattainment as a result of the lowering of the Pb NAAQS.


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