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

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


1
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

2
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

3
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

4
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

5
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)

6
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

7
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

8
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

9
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)

10
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?

11
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?

12
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

13
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

14
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)

15
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)

16
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

17
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?

18
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

19
Map Of Lead Sources and Pb-TSP Monitoring Sites
20
Layered Network Design
Source oriented monitors
Population oriented monitors
Near-roadway monitors
Increase monitoring with lower standard
21
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).

22
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

23
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

24
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?

25
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?

26
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

27
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?
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