Overview and Status of Lead NAAQS Review and Overview of Agency Technical Documents on Lead NAAQS Monitoring Issues

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Overview and Status of Lead NAAQS Review and
Overview of Agency Technical Documents on Lead
NAAQS Monitoring Issues

• Kevin Cavender and Joann Rice
• Presented at CASAC AAMMS Meeting
• March 25, 2008

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Outline

• Summary and status of lead NAAQS review
• Monitoring considerations for indicator options
• Draft Federal Reference Method (FRM) and Federal
  Equivalent Method (FEM) criteria for Pb-PM10
• Network design options
• Sampling frequency options

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Summary and Status of Pb NAAQS Review

• Final Criteria Document - 10/06
• Final Staff Paper 11/07
• Final Risk Assessment 11/07
• ANPR signed 12/07
• CASAC Review 12/07
• Court ordered deadline for proposed rule 5/1/08
• Court ordered deadline for final rule 9/1/08

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Monitoring considerations for indicator options -
Background

• Pb in TSP (Pb-TSP) is the current NAAQS indicator
• CASAC has recommended switching to Pb in PM10
  (Pb-PM10) as the indicator
• Problems with high-volume Pb-TSP sampler
• Difficulty in capturing spatial variability of
  ultra coarse particulates
• Staff Paper
• Recommended retaining current Pb-TSP indicator
• Increase activities toward collection and
  development of datasets to improve understanding
  of relationships between Pb-PM10 and Pb-TSP to
  support more informed consideration in next
  review
• ANPR
• Recommended retaining current Pb-TSP indicator
• Suggested modifying FEM criteria to allow for
  development of a low-volume Pb-TSP FEM
• Potential use of Pb-PM10 data where site specific
  data demonstrate good relationship between Pb-TSP
  and Pb-PM10

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Monitoring considerations for indicator options

• Retain Pb-TSP as indicator and allow use of
  Pb-PM10 data with scaling factors
• Change to Pb-PM10 as indicator
• Retain Pb-TSP (no change)

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Monitoring considerations for indicator options
(continued)

• Retain Pb-TSP as indicator and allow use of
  Pb-PM10 data with scaling factors
• Pb-PM10 for non-source sites would use an overall
  average equivalency factor and Pb-PM10 for source
  sites would use a near-source equivalency factor
  to scale up to Pb-TSP
• Avoids need for expanded Pb-TSP network
• Utilizes existing PM10 monitors where sites
  coincide with Pb NAAQS needs
• Maintains focus on all size Pb particles as
  health concern

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Monitoring considerations for indicator options
(continued)

• Change to Pb-PM10 as indicator
• Pb-PM10 level derived by applying equivalency
  factor to selected Pb-TSP target level
• Must be based on single equivalency factor which
  handicaps ability to accommodate different
  particle size situations
• Potential for perception that larger Pb particles
  are not of health concern
• May lead to controls not being applied to sources
  of ultra-coarse Pb particles

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Monitoring considerations for indicator options
(continued)

• Retain Pb-TSP (no change)
• Explicitly recognizes that all sizes of Pb
  particles contribute to human exposures and
  associated risk
• However, because of spatial and methodological
  variability of Pb-TSP, this option handicaps
  implementation of an effective monitoring
  network, i.e., one that assures identification of
  areas with potential to exceed NAAQS
• Does not address CASAC advice to change indicator
  to Pb-PM10
• Current FRM/FEM have low enough detection limit
  for likely range of proposed NAAQS

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Monitoring considerations for indicator options
Potential Scaling Factors

• Data available on 33 collocated Pb-TSP and
  Pb-PM10 monitoring sites
• Data supports different relationships for source
  oriented versus non-source oriented sites
• Source oriented Pb-TSP ranges from 1.4 to 2.1
  times higher than Pb-PM10 (data from 2 sites)
• Non-source oriented Pb-TSP ranges from 1.0-1.3
  times higher than Pb-PM10 (data from 31 sites)

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Monitoring considerations for indicator options
Charge Questions

• Considering issues such as sampler performance,
  size cuts, operator maintenance, integration with
  other measurement systems, and usefulness as the
  measurement system for the indicator, what are
  the advantages and disadvantages of sampling and
  analysis of Pb-TSP versus sampling and analysis
  of Pb-PM10?
• Is it appropriate to monitor for Pb-PM10 near Pb
  sources? And if so, under what conditions?

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Monitoring considerations for indicator options
Charge Questions (continued)

• One indicator option suggests scaling Pb-PM10
  monitoring data up to an equivalent Pb-TSP level
  in lieu of Pb-TSP monitoring data. Under what
  circumstances would it be appropriate to scale
  data (e.g., non-source oriented sites, low
  concentration sites) and when would it not be
  appropriate to scale data?
• We have limited collocated Pb-PM10 and Pb-TSP
  monitoring data. What types and scaling
  factors are appropriate to create using this
  data (e.g., non-source oriented, source
  oriented)? What levels are appropriate for the
  types of scaling factors identified in the white
  paper?

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Background on current FRM for Pb-TSP

• Existing FRM based on high-volume TSP sampler
  with atomic absorption (AA) analysis.
• 21 existing FEM all based on high-volume TSP
  sampler with various analysis options
• CASAC and others have concerns with TSP sampler
• Cut point is affected by wind speed and
  direction

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Draft Federal Reference Method (FRM) for Pb-PM10

• Sampling and analysis method considerations for a
  new FRM for Pb-PM10
• Sampling considerations
• Recently promulgated low-volume (16.7 L/min)
  PM10c sampler with 46.2-mm PTFE filters from
  PM10-2.5 FRM
• Advantages
• More demanding performance criteria of Appendix L
  (PM2.5 FRM) with sampling at local conditions
• Sequential sampling capability to meet increase
  sampling frequency if needed
• Affords network efficiencies and consistencies
  with other PM monitoring networks with low-volume
  samplers
• Consistent with QA requirements for PM2.5 and
  PM10-2.5

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Draft Federal Reference Method (FRM) for Pb-PM10

• Analysis Method Considerations
• X-Ray Fluorescence (XRF)
• Advantages
• No complicated sample preparation or extraction
  with acids prior to analysis
• Non-destructive
• Relatively cost effective
• Relatively low method detection limits (MDLs)
• On the order of 0.001 µg/m3 for low-volume
  collection
• Also used in other PM speciation monitoring
  programs (e.g., CSN and IMPROVE)

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Draft Revisions to the Federal Equivalent Method
(FEM) Pb Criteria

• Existing FEM Criteria contained in 40 CFR, Part
  53, Subpart C
• Criteria would need revisions for consistency
  with a potentially lowered Pb NAAQS and addition
  of a new Pb-PM10 FRM
• Also want to allow for approval of other analysis
  methods that are expected to meet precision, bias
  and MDL needs (e.g., ICP/MS, GFAA)
• Potential revisions include
• Reduction in the FEM testing concentration
• Addition of an MDL criteria
• Reduction in the audit concentrations
• Accommodation for 46.2-mm PTFE filter type
• Precision and bias left unchanged
• Making FEMs more generic (i.e., not requireing
  every State lab obtain a separate FEM)

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Draft QA Requirements

• Modifications would be needed to the QA
  requirements for Pb in order to accommodate
  Pb-PM10 monitoring
• Collocated sampling requirement
• Flow rate verification requirement
• Semi-annual flow rate audit
• Pb filter audits
• Performance Evaluation Program

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FRM/FEM Charge Questions

• Is it appropriate to use the low-volume PM10c FRM
  sampler as the Pb-PM10 FRM sampler?
• What other PM10 samplers should be considered as
  either FRM or FEM for the Pb-PM10 FRM?
• Is XRF an appropriate Pb-PM10 FRM analysis
  method?
• What other analysis methods should be considered
  for FRM or FEM for the Pb-PM10 FRM?
• Have we recommended appropriate precision, bias,
  and method detection limit requirements for FEM
  evaluation?

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Network design options - Background

• Currently States are required to operate 2 lead
  monitors in any area where they have exceeded the
  NAAQS in the last two years
• Existing network has poor coverage
• Many large lead sources do not have nearby
  monitors (only 2 of 27 emitting gt 5tpy)
• If standard is lowered the network will need to
  be expanded for -
• Better coverage of large lead sources
• Better population coverage
• CASAC commented that network needed to be
  expanded to include monitors near Pb sources, in
  urban areas, and near roadways

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Map Of Lead Sources and Pb-TSP Monitoring Sites
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Layered Network Design
Source oriented monitors
Population oriented monitors
Near-roadway monitors
Increase monitoring with lower standard
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Source Oriented Monitors

• Require 1 monitor at all Pb sources with actual
  emissions gt than threshold which could lead to
  ambient Pb concentrations over the NAAQS
• Allow EPA Regional Administrators to grant
  waivers where monitoring agency can demonstrate
  that source will not result in Pb concentrations
  gt X of the NAAQS
• Threshold would be based on final NAAQS level
  (lower NAAQS level would require lower
  threshold).

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Non-source Related Monitors

• A secondary objective of the Pb surveillance
  network might be to gather information on
  population exposure to Pb in ambient air
• Expected that non-source oriented monitors will
  show substantially lower concentrations than
  source oriented monitors,
• Helpful in understanding the risk posed by Pb to
  the general population
• Provide support for evaluation of spatial
  variation across urban areas
• Options
• Require 1 monitor in urban areas with population
  gt some threshold
• Base the number of required monitors on the most
  recent design value and the population of the
  urban area

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Roadway Monitoring

• CASAC has indicated they believe that
  re-entrained Pb from roadways is a major
  contributor to urban Pb exposure
• Considerable uncertainty exists on Pb
  concentrations near roadways
• Options to facilitate collection of data on Pb
  concentrations near roadways
• Add additional minimal monitoring requirements
  for roadways
• Allow roadway monitors to be used to meet
  non-source monitoring requirements

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Network Design Charge Questions

• What types of monitoring sites should be
  emphasized in the network design (e.g., source
  oriented monitors, population monitors, near
  roadway monitors)?
• We are considering proposing requirements for
  monitoring near sources exceeding an emissions
  threshold and discuss a number of options for
  determining this threshold in the white paper.
  What options should be considered in establishing
  an emissions threshold?
• We are considering proposing requirements for
  non-source oriented monitoring in large urban
  areas to provide additional information on
  ambient air concentrations in urban areas.
  Considering other monitoring priorities and a
  potential requirement for Pb monitoring near
  sources, what size of a non-source oriented Pb
  network is appropriate?

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Network Design Charge Questions (continued)

• What factors should we base non-source oriented
  monitoring requirements on (e.g., population,
  design value)?
• We are considering proposing requirements for Pb
  monitoring near roadways and interstates. Is it
  appropriate to include separate monitoring
  requirements for near roadway monitoring, or
  should near roadway monitors be a part of the
  non-source oriented monitoring requirement?
• Under what conditions would it be appropriate to
  waive the monitoring requirements for either
  source or non-source oriented monitors?

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Sampling Frequency

• If we move to a monthly averaging time for the
  NAAQS, we anticipate a need to increase the
  required sampling schedule (currently 1 sample
  every 6 days)
• OAQPS will be developing DQOs for Pb sampling
  that will assist in selecting an appropriate
  sampling frequency
• Options
• Change to 1 in 3 days requirement, or
• Change to 1 in 3 day requirement with an option
  to relax to 1 in 6 day sampling if DV lt 85 of
  standard
• Note More frequent sampling is a key reason we
  need a low-volume FRM which will allow for
  sequential sampling

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Sample Frequency Charge Questions

• What sampling frequency would be appropriate if
  the Pb NAAQS is based on a monthly average?
• Is it appropriate to relax the sampling frequency
  in areas of low Pb concentration? If so, at what
  percent of the Pb NAAQS?
• Is it appropriate to relax the sampling frequency
  in areas considerably higher than the NAAQS? If
  so, at what percent of the Pb NAAQS?