Model For Relating PM2.5 Federal Reference Method & Nephelometer Measurements

Presented by

Jenny Parikh

04/21/23 2EPA AQI Conf. 2/3-5/02

Agenda

What was doneValue to PublicHow the model is developedWhat’s Next

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GOAL

Develop Statistical Linear regression model relating PM2.5 FRM and Nephelometers (continuous monitors)

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WHY

FRM is used for NAAQS compliance (FILTER based)• 1999-to date• PM2.5 measurement are below NAAQS• Continuous Monitor data is available

Temporally resolved data : Diurnal cycles Need to estimate PM2.5 in real time (AQI) Push from EPA to complete Real time network QA TOOL

04/21/23 5EPA AQI Conf. 2/3-5/02

VALUE TO PUBLIC

Ability to represent unhealthy air conditions while it is occurring

Part 58.50 of 40CFR requires all MSAs with population of 350,000 or greater to report daily AQI

04/21/23 6EPA AQI Conf. 2/3-5/02

METHODOLOGY

Determine required environmental measurements, suitable data and data reduction

Perform exploratory data analyses• Histogram • Scatter plots and outliers• Time series analyses

Determine the “best” model Evaluate the ability of the model to estimate PM2.5

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Guidance Document

04/21/23 8EPA AQI Conf. 2/3-5/02

Guidance document

http://www.epa.gov/ttn/amtic/files/ambient/monitorstrat/aqidqorept.pdf

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0 40 8020Miles

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Nephelometer Monitoring Sites

Nephelometer Sites

2005

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MODEL DEVELOPMENT

Eastern Sites• Chewelah, Coleville, Pullman, Ritzville, Walla Walla,• Kennewick, Yakima, Twisp, Moses Lake……

Western Sites• Longview, Lacey, North Bend, Yew Street, Beacon Hill,

Redmond, Bellevue Goldfarb, Vancouver…

04/21/23 11EPA AQI Conf. 2/3-5/02

RESULTS: Chewelah

FRM vs Modeled FRM

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5.0

10.0

15.0

20.0

25.0

FRM 2.5

Modeled FRM

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Next Step

Strong FRM- CM relationship indicated it was worth considering a comparison of CM and FRM that are not collocated

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How the E. WA model was developed

FRM and Neph Data for the sites started from 04/01 till todate, about 75 days of data

44 days where all five sites had data

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Comparison of Nephelometers

Comparison of Neph from all sites

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43

Colville Bscat

Chew elah Bscat

PullmanBscat

RitzvilleBscat

Ww alla Bscat

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Comparison of FRMs from all E. WA sites

Comparison of FRMs

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5.0

10.0

15.0

20.0

25.0

30.0

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43

Colville FRM

Chew elahFRM 2.5

PullmanFRM

Ritzville FRM

W Walla FRM

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Analysis of Data Strong CM-FRM relationship was observed

Compared CM and FRM data that are not co-located

Strong relationship indicated a possibility of developing a model using the average of the set of FRM measurements with CM measurements

This also gives measurements that are better representative of the overall region

04/21/23 17EPA AQI Conf. 2/3-5/02

Colville and E. Washington Model

Colville FRM and East. WA model

0.05.0

10.015.020.025.030.0

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43Colville FRMEast.Wa model

04/21/23 18EPA AQI Conf. 2/3-5/02

Pullman and E. WA Model

Pullman vs. Eastern Wa model

0.02.0

4.06.0

8.010.0

12.014.0

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43PullmanFRMEastern WA model

04/21/23 19EPA AQI Conf. 2/3-5/02

Eastern Washington Model

Colville FRM and East. WA model

0.05.0

10.015.020.025.030.0

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43Colville FRMEast.Wa model

04/21/23 20EPA AQI Conf. 2/3-5/02

Ritzville and E. Washington Model

Ritzville vs. Eastern WA model

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5.0

10.0

15.0

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43Ritzville FRM

Eastern WA model

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WallaWalla and E.WA Model

WWalla vs. Eastern Wa model

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5.0

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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43W Walla FRM

Eastern WA model

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Models All Eastern Sites PM2.5 correlated = 10 (0.710771(logBscat)+1.325303)

This model is applied to Lacrosse, Rosalia, Starbucks, Mesa)

Final NorthBend PM2.5 correlated = 10 (0.892521 (log Bscat)+1.394775) Previous North BendPM2.5 correlated = 10 (0.93537 (log Bscat)+1.424513)

Previous Beacon Hill PM2.5 correlated = 10 (0.689323 (log Bscat)+1.390065)

( R2 = 0.84) New Beacon Hill PM2.5 correlated = 10 (0.793263 (log Bscat)+1.420227)

( R2 = 0.90)

NWAPA Model PM2.5 correlated = 10 (0.755345 (log Bscat)+1.36943)

This is applied to Mt. Vernon

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IMPLICATIONS

Valuable tool for Eastern WA – covers large geographical area with Nephelometer

Divest from PM2.5 FRM network- optimization and modification

Resource allocations• Workforce demands• Monitor costs

04/21/23 24EPA AQI Conf. 2/3-5/02

WHAT’S NEXT

Refine and update with additional data for Western Washington Model• Quarterly / Seasonal basis

Additional sites e.g; Stevenson (Bonneville, Mt. Zion, Wishram), Leavenworth

04/21/23 25EPA AQI Conf. 2/3-5/02

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0 40 8020Miles

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Nephelometer Monitoring Sites

Nephelometer Sites w/correlated PM2.5Nephelometer Sites

2005

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Nephelometer/Correlated PM2.5

Most of our nephelometer site data has been analyzed to create a correlation to PM2.5 .

Those sites with a PM2.5 correlation are shown on the site operators’ page https://fortress.wa.gov/ecy/aqp/Site/ AND the public page as NPM2.5 https://fortress.wa.gov/ecy/aqp/Public/aqn.shtml