ARTS 110806

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Austin – Round Rock Toxics Study (ARTS): 

Austin – Round Rock Toxics Study (ARTS) Albert Hendler and Shona Briscoe URS Corporation November 8, 2006

ARTS Objectives: 

ARTS Objectives Measure and report levels of common urban air toxics Identify chemicals of potential concern Establish baseline for measuring trends Inform the public

Project Team: 

Project Team Sponsored by U.S. EPA Region 6 Managed by Capitol Area Council of Governments Field sampling by URS Corporation Laboratory Analysis by ERG

Austin-Round Rock Quick Facts: 

Austin-Round Rock Quick Facts 2005 population estimate – 1.2 million 38th largest U.S. MSA in 2000 Two largest counties, Travis and Williamson, ranked 85th and 376th in 1999 total NEI HAPS Emissions (among 1207 U.S. urban counties)

ARTS Overview: 

ARTS Overview 5 sampling sites 12-month sampling duration Jun 05 – Jun 06 24-hour sampling period Every 12th day sampling frequency Approximately 30 samples per site Field duplicates at one site 83 chemicals target chemicals: 59 volatile organic compounds 12 carbonyls 12 metals

Measurement Methods: 

Measurement Methods

ARTS Sampling Equipment: 

ARTS Sampling Equipment

Data Treatment: 

Data Treatment ½ the detection limit (DL) was substituted for all non detects ½ the DL was substituted for all values reported below the DL Average field blank levels for carbonyls and metals were subtracted from reported ambient values

Data Analysis: 

Data Analysis Comparison with reference levels Spatial variation Comparison with other cities

Reference Concentration Levels: 

Reference Concentration Levels EPA RfC and similar values as reported by EPA (2005) 'Health Effects Information used in Cancer and Noncancer Risk Characterization for the 1999 National-Scale Assessment' http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf 10-5 cancer risk level

ARTS Pollutants that Exceeded RfC: 

ARTS Pollutants that Exceeded RfC

U.S. 2005 Annual Average Acrolein Levelsfrom http://www.epa.gov/air/data/index.html: 

U.S. 2005 Annual Average Acrolein Levels from http://www.epa.gov/air/data/index.html 5 of the 6 highest annual averages in AQS were at Austin-Round Rock sites

Travis and Williamson County Acrolein and Total HAP Emissions Rankings (U.S. Urban Counties): 

Travis and Williamson County Acrolein and Total HAP Emissions Rankings (U.S. Urban Counties)

Travis and Williamson County Acrolein Sources (1999 NEI): 

Travis and Williamson County Acrolein Sources (1999 NEI)

Acrolein Time Series: 

Acrolein Time Series Highest levels measured in summer and fall

Acrolein Canister Duplicates Average RPD = 50% (N=15): 

Acrolein Canister Duplicates Average RPD = 50% (N=15) Good precision for 12 of 15 sample pairs

Comparison of NATA 1999 Acrolein Estimates with ARTS 2005-06 Measured Concentrations: 

Comparison of NATA 1999 Acrolein Estimates with ARTS 2005-06 Measured Concentrations Measured levels exceed 1999 NATA estimates by more than 10x

ARTS Pollutants that Exceeded 10-5 Cancer Risk Levels: 

ARTS Pollutants that Exceeded 10-5 Cancer Risk Levels

U.S. 2005 Annual Average Benzene Levels from http://www.epa.gov/air/data/index.html: 

U.S. 2005 Annual Average Benzene Levels from http://www.epa.gov/air/data/index.html Webberville Rd. benzene average was greater than 80% of 450 annual averages (2005) reported in AQS

Travis and Williamson County Benzene and Total HAP Emissions Rankings (U.S. Urban Counties): 

Travis and Williamson County Benzene and Total HAP Emissions Rankings (U.S. Urban Counties)

Travis and Williamson County Benzene Sources (1999 NEI): 

Travis and Williamson County Benzene Sources (1999 NEI)

Comparison of NATA 1999 Benzene Estimates with ARTS 2005-06 Measured Concentrations: 

Comparison of NATA 1999 Benzene Estimates with ARTS 2005-06 Measured Concentrations NATA estimates exceed measured averages by 35-111%

Comparison of NATA 1999 Excess Cancer Risk Estimates with ARTS 2005-06 Measured Levels: 

Comparison of NATA 1999 Excess Cancer Risk Estimates with ARTS 2005-06 Measured Levels NATA estimates within ± 40% of calculated excess risks

Percentages of Total Excess Cancer Risk Attributed to ARTS Pollutants – All Sites: 

Percentages of Total Excess Cancer Risk Attributed to ARTS Pollutants – All Sites

Percentages of Total Excess Cancer Risk Attributed to ARTS Pollutants – Webberville Rd.: 

Percentages of Total Excess Cancer Risk Attributed to ARTS Pollutants – Webberville Rd.

ARTS Spatial Variability(Highest Site Average – Lowest Average) ÷ Lowest Average: 

ARTS Spatial Variability (Highest Site Average – Lowest Average) ÷ Lowest Average

Slide27: 

Comparison of Results with Data from Other Cities 10-city air toxics pilot study 2001-2002 http://www.ladco.org/toxics.html

Slide28: 

ARTS Average Levels Compared to Pilot Cities Average Levels

Summary (Page 1 of 3): 

Summary (Page 1 of 3) 83 chemicals in ambient air measured by the Austin-Round Rock Toxics Study… Acrolein levels exceeded EPA RfC by wide margin Among the highest average levels reported in U.S. Duplicate precision appears good Strong seasonal variation (summer-fall maximum) No agreement with NATA 1999 predictions Benzene levels exceeded 10-5 cancer risk level at 1 site – Webberville Rd Average benzene at Webberville Rd. was greater than 80% of the 2005 annual average benzene levels reported in AQS Reasonably good agreement with NATA 1999 predictions Apparent mobile source influence at Webberville Rd.

Summary (Page 2 of 3): 

Summary (Page 2 of 3) Surprisingly good agreement between calculated excess cancer risk and NATA 1999 estimates Greatest average excess cancer risks attributed (in decreasing order) to… Carbon tetrachloride Benzene 1,3-butadiene Acetaldehyde

Summary (Page 3 of 3): 

Summary (Page 3 of 3) Average levels of 62 of the measured chemicals varied by less than a factor of two from site to site Includes 12 of 18 NATTS core pollutants Site with highest levels of several VOC appears to have greater mobile source influence The average levels of core pollutants measured in Austin-Round Rock were generally lower than the average levels measured in the 10 Cities Air Toxics Pilot Study

Future Work: 

Future Work Source apportionment using Positive Matrix Factorization (in progress) Additional field measurements, quality assurance, and methods comparison for acrolein (discussing possible scope with TCEQ)

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