National Air Toxics Assessments (NATA)

1. National Air Toxics Assessments (NATA) June 2009 Conrad Chin US EPA

2. What is NATA? Characterization of air toxics across the nation Nationwide assessment with census tract resolution for 177 HAPs plus diesel PM Emissions, modeled ambient concentrations and estimated inhalation exposures from outdoor sources Cancer and noncancer risk estimates for the 133 HAPs with health data based on chronic exposures Tools for State/Local/Tribal Agencies (and EPA) to prioritize pollutants, emission sources and locations of interest Provides a starting point for local-scale assessments Focuses community efforts Informs monitoring programs Allows public to better understand the air toxics problem in the U.S. and in their communities Additional health risk from inhaling air toxics

3. NATA History • 1996 NATA • Based on 1996 NTI • Released May 2002 (6 year lag) • 33 HAPS • 1999 NATA • Based on 1999 NEI • Released Feb 2006 (7 years lag) • 177 HAPs • 2002 NATA • Based on 2002 NEI • Expected release in 2008 • 294 pollutants

4. Who Uses NATA? • EPA • Data for standard setting • MSAT Rule used NATA for current and projected risk levels • Risk and Technology Review • Area Source rulemaking • Air toxics monitoring • NATTS priority HAP/site locations • Support urban monitoring efforts • Toxic to criteria program • Overlay “hot spots” with nonattainment areas • Evaluate the toxic component of PM • States • Many state air toxic program sets priorities using NATA • Identify gaps in emissions inventories • Communities • Information

5. Emission Inventory Development Components of the NATANational-Scale Assessment Dose- Response Assessment Estimation of Inhalation Air Dispersion Modeling Risk Ambient Exposure Assessment/ Concentration Modeling Characterization (HAPEM) Comparison with Ambient Concentration Monitoring 5

6. 1999 National-Scale Assessment Risk Characterization – Significant Pollutants Cancer National drivers1 Benzene Regional drivers2 Arsenic compounds Benzidine 1,3-Butadiene Cadmium compounds Carbon Tetrachloride Chromium 6 Coke oven Ethylene oxide Hydrazine Naphthalene Perchloroethylene POM 1 At least 25 million people exposed to risk > 10 in 1 million 2 At least 1 million people exposed to risk > 10 in 1 million OR At least 10,000 people exposed to risk > 100 in 1 million

7. 1999 National-Scale Assessment Risk Characterization – Significant Pollutants NonCancer National drivers3 Acrolein Regional drivers4 Antimony Arsenic Compounds 1,3-Butadiene Cadmium compounds Chlorine Chromium 6 Diesel PM Formaldehyde Hexamethylene 1-6-diisocyanate Hydrazine Hydrochloric acid Maleic anhydride Manganese compounds Nickel compounds 2,4-Toluene Diisocyanate Triethylamine 3At least 25 million people exposed to a hazard quotient (HQ) > 1.0 4At least 10,000 people exposed to HQ >1 Blue indicates new drivers since 1996

11. 1999 NATA Cancer Risk Source Sector Contributions 11% Major 19% 41% Area/Other Onroad Nonroad Background 24% 5% Average Risk: 48 in a Million

12. 1999 NATA Noncancer (Respiratory) Risk Source Sector Contributions 3% 3% 16% 22% Major Area/Other Onroad Nonroad Background Average Hazard Index = 6.4 56%

13. 1999 NATA - Pollutant Contribution to Average Cancer Risk (48 in a million) Ethylene_oxide POM (Group 2) Other 1% 1% 8% p_Dichlorobenzene Lets take a closer look at Benzene 1% Benzene Ethylene_dichloride 22% 2% Perchloroethylene 3% Chromium_VI 3% Coke_Oven_Emissions 4% Naphthalene 5% Hydrazine 10% Bis_2_ethylhexyl_phthalate 5% Tetrachloroethane_1_1_2_2 5% Butadiene 8% Acetaldehyde 6% Ethylene_dibromide Carbon_tetrachloride 8% 7%

14. Key Source Categories: Benzene 1999 Emissions Emissions Trends in the 1990s 2% Oil & Natural Gas Production 1% Gasoline Distribution (Stage I) 493433 6% Residential Wood Heating 9% Other Categories (613 categories) * 14% Open Burning – Prescribed and Wild Fires 19% Mobile Nonroad Net emissions reductions (’90 to ’99) = 142,657 tons Mobile Onroad: 140,343 tons Oil & Natural Gas: 11,892 tons Petroleum Refineries: 5,654 tons Mobile Nonroad: 4,591 tons 49% Mobile Onroad * 1990 estimates do not reflect latest methodology used in 1999 estimates for prescribed and wildfires

15. 1999 NATA - Pollutant Contribution to Average Noncancer Risk (HI=6.4) Methyl_bromide Toluene_diisocyanate_2_4 1% 1% Other Bis_2_ethylhexyl_phthalate 2% 2% Chlorine Lets take a closer look at Acrolein Acetaldehyde 2% 3% Formaldehyde 3% Acrolein 86%

19. 1999 NATA - National Scale Assessment Predicted County Level Ambient Benzene Concentrations

20. WY NJ

28. 1999 National-Scale Assessment Risk Characterization – Geographic Risk Distribution Cancer Risk Spatially, majority of country predicted to have risk between 1 and 25 in a million Most urban locations - greater than 25 in a million Transportation corridors and some locations - greater than 50 in a million risk Several counties - greater than 100 in a million risk Noncancer Over 40% of counties - hazard index greater than 1 Several counties - hazard index greater than 10 Highest risk counties coincide with locations where criteria pollutant issues are significant

29. Overall Summary Of 1999 NATA Results The average cancer risk for 1999 is 48 in a million Comparable to 1996 NATA of 55 in a million Benzene is most significant carcinogen The average noncancer risk for 1999 is 6.4 (hazard index for respiratory) Comparable to 1996 NATA of 5.2 Acrolein a majority of this risk

30. Risk Decision Criteria Cancer risk Aggregate risk from all carcinogens < 1 in a million: No further action >100 in a million: Reduce the risk >1 but <100 in a million: Look for feasible cost-effective risk reductions Noncancer effects Hazard index (HI) = aggregate of all noncarcinogens by target organ HI<X1: No further action HI>Y2: Reduce the risk HI>X but <Y: Look for feasible cost-effective risk reductions 1: “De minimis” HI currently under discussion, likely default in 0.2-1.0 range. 2: Upper end of HI range to be source-specific, typically between 1 and 10.

31. For more information on NATA http://www.epa.gov/ttn/atw/natamain/