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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• 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)

Draft Federal Reference Method (FRM) for Pb-PM10

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• 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 FEM’s more generic (i.e., not requireing every State lab

obtain a separate FEM)

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

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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 > 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 w

ith lower standard

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Source Oriented Monitors

• Require 1 monitor at all Pb sources with actual emissions > 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 > 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 > 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 < 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?