STN/IMPROVE Comparison Study Preliminary Results Paul Solomon, ORD Tracy Klamser-Williams, ORIA Peter Egeghy, ORD Dennis Crumpler, OAQPS Joann Rice, OAQPS Others PM Model Performance Workshop February 10, 2004

2 Discussion Topics Study Background STN and IMPROVE Protocol Differences Preliminary STN versus IMPROVE Data Comparison Results and Conclusions Next Steps

3 STN/IMPROVE Intercomparison Why did we do this study? To establish data comparison and relationships for historical data Collecting data since fall ’01 3 areas (1 urban/rural pair) Presenting Analysis of Oct ’01 to Sept ’02 data Finishing QA of first year data Final results early ’04

4 STN/IMPROVE Intercomparison

5 It is Not Just the Analysis Methods From Monitor Inlet* to Data Mgmt Sample Collection Handling, Shipping, and Storage (after collection) Chemical Analysis  Extraction  Analysis Methods Standards  Or Lack Thereof for Ambient Field PM Measurements Data Manipulation  Blank Subtraction and Artifacts Comparative Protocol Analysis * Begins w/ Filter Purchase, Acceptance Testing, Handling & Storage

6 How Protocols Might Affect Results Between Networks * Inlets  Effect on Slope of Efficiency Curve and Cutpoint Flow Rate Differences  Effect of Pressure Drop, Face Velocity and Residence Time Influences Collection of Semi-Volatiles Negative vs Positive Artifacts Blank Values Likely Different * Not an Exhaustive List

7 Between Networks (cont) * Shipping and Storage  STN at Reduced Temperatures  IMPROVE at Ambient Temperatures Influences Collection of Semi-Volatiles Use of IMPROVE in Urban Areas  Higher Flow Rate, Smaller Filters Filter Clogging Potential in urban areas Effect on Semi-volatiles  Denuder Capacity and Efficiency Na 2 CO 3 vs MgO Refurbishing Frequency of Na 2 CO 3 How Protocols Might Affect Results * Not an Exhaustive List

8 Bottom Line Given All these Differences, Do the Networks Provide Similar Results for Mass and the Components ?

9 Median Ratio of STN/IMPROVE

10 Urban – Rural Temporal Analysis: PM 2.5 Mass Haines PointDolly Sods Phoenix Tonto

11 Urban – Rural Comparison of Means: PM 2.5 Mass Annual Average Results  East Coast Sites Have Higher Conc. than West Coast Sites  Urban Site Levels Exceed Rural Sites by %  Similar Agreement, within ~10%, is Observed at Both Urban and Rural Sites, with Slightly Better Average Agreement at Urban Sites 9.0%* -5.1% 4.3% 11.0% 11.3% 3.3% 9.5% 10.8% 5.9% * Relative Percent Diff. (STN-IMP)/((STN+IMP)/2)*100 Urban ( E  W) Rural ( E  W )

12 Urban – Rural Temporal Analysis: Sulfate Haines Point Dolly Sods Beacon Hill Mt. Rainier

13 Urban – Rural Comparison of Means: Sulfate Annual Average Results  East Coast Sites Have Higher Conc. than West Coast Sites  Urban Site Levels Exceed Rural Sites By 50 to 70% (Avg 48%) Based on STN Data and By % (Avg 37%) Based on IMP Data  There Is Better Agreement On Average at Urban Sites  The Dolly Sods STN Sulfate Data For June & July 2001 Will Be Flagged as Invalid Due to a Flow Controller Problem – These Data Contribute Significantly to the Larger Difference Between the Two Networks at Dolly Sods -0.9% -23.4% -7.5% -24.2% 12.0% 9.5% -6.0% -13.7% -9.0% * Relative Percent Diff. (STN-IMP)/((STN+IMP)/2)*100 Urban ( E  W) Rural ( E  W )

14 Urban – Rural Temporal Analysis: Nitrate Haines Point Dolly Sods Beacon Hill Mt. Rainier

15 Urban – Rural Comparison of Means: Nitrate Annual Average Results  On Average, Nitrate Conc Are Low, < 1.4 µg/m 3  East Coast Sites Have Higher Conc. than West Coast Sites  Paired Urban Site Levels Exceed Rural Sites by ~ Factor of 3  By Site, Samplers Agree Within About 30% on Average  At Beacon Hill the Difference is Largest at Higher Conc as Seen in the Temporal Distribution 11.7% 13.1% -31.9% 13.7% -20.8% -3.3% 0.5% -2.8% -0.2% Urban ( E  W) Rural ( E  W ) *Relative Percent Diff. (STN-IMP)/((STN+IMP)/2)*100

16 Urban – Rural Temporal Analysis: OC Haines Point Dolly Sods Beacon Hill Mt. Rainier In General IMP < STN

17 Urban – Rural Temporal Analysis: OC Haines Point *Note Negative Values in STN After Blank Correction After STN Blank Correction IMP ~ STN* Mostly On Average Within 15% STN Values Blank Corrected

18 Annual Average Results  East and West Coast Sites Can Have Similar Concentrations  STN Urban Site Levels Exceed Rural Sites by %  Rural Sites Tend to Agree Better Than Urban Sites Before Blank Correction  Values Agree Better, but Blank Correcting STN Results in Negative Numbers That Seem to Be More Prevalent in the Fall & Winter Urban – Rural Comparison of Means: OC Blank Correcting STN OC Values Improves the Comparison Between STN and IMPROVE at Most Locations STN Blank Values Are Based on Trip and Field Blanks and Averaged Over the Time Period of the Study Anderson = 1.3 ug/m 3 Haines Pt, Dolly Sods MetOne = 1.4 ug/m 3 Phoenix, Tonto URG = 0.3 ug/m 3 Beacon Hill, Mt Rainier Urban ( E  W) Rural ( E  W )

19 Urban – Rural Temporal Analysis: EC Haines PointDolly Sods Beacon HillMt Rainier

20 Urban – Rural Comparison of Means: EC Annual Average Results  EC Data Did Not Require Blank Correction  Urban Conc Are ~ 2X Rural Conc  Factor of 2 Not Observed Between STN and IMPROVE At Urban or Rural Sites  Better Agreement at Urban Sites (<10%) than at Rural Sites (± ~ 30%) -9.6%* -1.4% 0.4% -28% 23% -41% -3.7% -15% -6.2% Urban ( E  W) Rural ( E  W ) *Relative Percent Diff. (STN-IMP)/((STN+IMP)/2)*100

21 Concentrations at Rural Sites Lower for Most Species at Most Sites Less Consistency (Greater Scatter) Observed at Rural Sites Higher Data Capture Observed at Urban Sites Mass and Sulfate Agreed Well Typically within 10% for Mass and 20% for Sulfate Organic Carbon Agreed Better After STN Data Blank Corrected Conclusions

22 Species at Higher Concentrations Agree Better MDL & Blanks Potential Issue Between Network Agreement Site-to-Site Variations Observed for All Species Even After a Thorough Review of the Data and Outliers Questionable Data Still Remain Factor of 2 Difference not Observed Between STN and IMPROVE EC Conclusions (cont’d)

23 Finalize report on first year of data from 6 sites Conduct study to determine the effects of shipping conditions Begin analyzing quartz filters from STN sites using IMPROVE protocol Sponsoring projects to specifically look at the effect of carbon meas. protocols on concentration data Next Steps

24 Expanding IMPROVE collocation to nine additional “STN” sites in 2003/2004 New York City Atlanta Pittsburgh Birmingham Detroit Chicago Houston (SS) Riverside-Rubidoux Fresno (SS) Next Steps

25 Disclaimer & Acknowledgements This work has been funded wholly by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products do not constitute endorsement or recommendation for use. Acknowledgements: This work was supported by the National Park Service and EPA. Staff from UC Davis, DRI and NPS personnel have played a significant role in collection and analysis of samples in the IMPROVE Network. Research Triangle Institute has played a significant role in preparing and analyzing samples for the STN network, as well as state site operators who have meticulously been collecting samples since October 2001, which continues to date. Complete Authors List: Solomon, Paul, A. (EPA, ORD, Las Vegas), Crumpler, Dennis (EPA, OAQPS, RTP), Klamser-Williams, Tracy (EPA, ORIA, Las Vegas), Egeghy, Peter, Homolya, James, Pitchford, Marc (EPA, OAQPS, Las Vegas), Rice, Joann, Ashbaugh, Lowell (UC Davis, Sacramento), Orourke, James (RTI, RTP), Frank, Neil, McDade, Charles, Flanagan, James, and Rickman, Edward