New Source Review for Air Toxics

1. New Source Review for Air Toxics November 2, 2005 Peter J. Moore Yorke Engineering 949-248-8490 x24

2. What is ToxicsNew Source Review (NSR)? • Evaluation of the health risk impacts to nearby exposed individuals (receptors) • Calculate health risk indices • Health risk indices cannot exceed thresholds

3. When is Toxics NSR Applied? • When a new or modified source causes an increase in Toxic Air Contaminants (TAC), Toxics NSR is required • SCAQMD Rule 1401 – New Source Review of Toxic Air Contaminants • Also Rule 219 permit-exempt equipment if health risk may exceed thresholds

4. Implications of Toxics NSR • Permit denied if calculated health risk is too high • Public notice required if cancer risk increase exceeds 1 in one million • CEQA is triggered if combined project cancer risk increase exceeds 10 in one million • May require Environmental Impact Report

5. Implications (continued) • May set permit conditions • Example: Natural Gas Engine • Toxic Air Contaminants from internal combustion must be evaluated for Toxics NSR • If health risk calculations show that a limit on operation is necessary to stay below health risk thresholds, a daily or monthly limit on natural gas use may become a permit condition • Carefully consider all possible toxic emissions for any new source

6. What Toxics are Considered? • Toxic Air Contaminants (TAC) are listed in Rules 1401 and 1402 • Carcinogenic: 153 compounds • Acute: 58 chemicals • Chronic: 125 chemicals • Risk factors are assigned by the California EPA Office of Environmental Health Hazard Assessment (OEHHA) • New TAC’s being added over time

7. Health Risk Index - MICR • Maximum Individual Cancer Risk (MICR) • Long term impact • Probability that an individual will contract cancer over 70 years (resident receptor) or 40 years (commercial receptor) • Must be < 1 x 10-5 (10 in one million) for new equipment • <1 x 10-6 to avoid public notice

8. Health Risk Index - Chronic • Chronic Hazard Index (HIC) • Long term, non-cancer health effects • Must be < 1.0 for all target organs

9. Health Risk Index - Acute • Acute Hazard Index (HIA) • Short term (1-hour average) health effects • Must be < 1.0 for all target organs

10. What Are Target Organs? • Specific systems in the human body that are affected by TACs

11. Risk Assessment Tiers • Tier 1: Screening Emission Levels • Use Table 1A to check if emission rates are below thresholds • Tier 2: Screening Risk Assessment • Use Tables 2-10 to determine dispersion factors, etc. • Tier 3: Screening Dispersion Modeling • Use SCREEN3 to determine dispersion factors • Tier 4: Detailed Risk Assessment • Use HARP for highest fidelity model, full meteorology Less Conservative

12. Tier I Screening Evaluation • Max Annual Controlled Emissions (tons/year) • Max Hourly Controlled (lbs/hr) • Look up tables in: “Risk Assessment Procedures for Rules 1401 and 212” • Check for most recent version! • If emissions are lower than screening levels, Rule 1401 is satisfied. If not, proceed to Tier II

13. Tier II Health Risk Assessment • Max Annual Controlled Emissions (tons/year) • Max Hourly Controlled (lbs/hr) • Look up tables in: “Risk Assessment Procedures for Rules 1401 and 212” • If health risk indices lower than thresholds, Rule 1401 is satisfied. If not, proceed to Tier III

14. Tier II Risk Assessment for MICR • MICR = CP x DI x MP • CP: cancer potency factor (mg/kg-day)-1 • DI = Dose inhalation (mg/kg-day) • DI = Cair x DBR x EVF x 10-6 • Cair = concentration in air (µg/m3) • DBR = daily breathing rate (L/kg-day) • EVR = Exposure value factor (unitless) • 1 x10-6 = convert µg to mg(10-3 mg/µg), liters to cubic meters (10-3 m3/l) • Cair = Qtonsx X/Q x AFannx MET • Qtons = Emission rate (tons/year) • X/Q = Dispersion Factor ((µg/m3)/(ton/yr) • AFann = Annual Averaging factor • MET = meteorological correction factor (unitless) • MP: multipathway factor (unitless) • MICR = CP x ((Qtonsx X/Q x AFannx MET) x DBR x EVF x 10-6) x MP

15. Chronic Index Equation HIC Chronic hazard index (calculated for each target organ) TACSum of the contribution for each Toxic Air Contaminant (TAC) QyrTACEmission rate of each TAC (tons/year) X/Q Annual average dispersion factor (g/m3)/(ton/year) RELTACChronic Reference Exposure Level (g/m3) for each TAC MP Multi-pathway adjustment factor (n.d.) MET Meteorological correction factor (n.d.)

16. Acute Index Equation HIA Acute hazard index (calculated for each target organ) TACSum of the contribution for each Toxic Air Contaminant (TAC) QhrTACEmission rate of each TAC (lb/hour) X/QhrHourly average dispersion factor (g/m3)/(lb/hour) RELTACAcute Reference Exposure Level (g/m3) for each TAC

17. Cancer Burden Calculation • Only Needed if MICR >10-6 • Estimate Area (km2) with Risk >10-6 • Multiply Area by 4,000 - 7,000 persons/ km2 • Multiply Total Persons by MICR • If Burden >0.5 • More detailed calculations or modeling required

18. Tier III Health Risk Assessment • Similar to Tier II • Use SCREEN3 to determine dispersion factors (X/Q) instead of from tables • Exhaust temperature and velocity are included • Simple building downwash effects • Single source • Equation is the same • If health risk indices lower than thresholds, Rule 1401 is satisfied. If not, proceed to Tier IV

19. Tier IV Health Risk Assessment • Most detailed health risk assessment • Requires details of building dimensions, local topography, and local meteorology • Use Hot Spots Analysis and Reporting Program (HARP) to calculate dispersion factors and health risk indices • Free download from CARB website www.arb.ca.gov/toxics/harp/harp.htm • Multiple sources in different locations

20. TAC’s from Natural Gas • Ventura County APCD did testing of internal & external combustion equipment in 1995 for TAC’s • “Ventura Factors” can be used for emission factors for external combustion only • Use EPA’s AP-42 emission factors for internal combustion

21. TAC’s from External Combustion *As determined by Ventura APCD

22. TAC’s from Internal CombustionEPA: AP-42 Emission Factors, Table 3.2-3

23. Rule 1401 Limitations • MICR of 1 X 10-6 Without T-BACT * • MICR of 1 X 10-5 With T-BACT • Cancer Burden, excess cancer cases in the population subject to a risk greater than (1 x 10-6), of 0.5 • Acute and Chronic Hazard Index of < 1 * T-BACT Criteria Similar to Existing BACT

24. Rule 1401 Exemptions • Emergency Internal Combustion Engines • Modifications with no increase in toxic emissions • Functionally identical replacement • Contemporaneous Risk Reductions • No MICR increase at any location >1x10-6, and • Reduction occurs within 100 m of new equipment • Alternative Hazard Index <10

25. Example • Facility adding three large, natural-gas fueled, cogeneration engines • Four existing emergency diesels • Nearby residents • Each engine passed Rule 1401 with MICR of 9 in one million • CEQA triggered due to combined MICR of 27 in one million

26. Example (continued) • We calculated that cogeneration engines resulted in less usage of diesel backup engines • Diesel health risk is high • Contemporaneous health risk reduction allowed project to proceed without requiring an Environmental Impact Report

27. Risk is Dependent On: • Source and Receptor Location • Emission Rate • Emission Species • Meteorology • Stack Parameters • Operating Schedule

28. Strategies • Locate equipment away from adjacent residents or workers • Raise stack height • Perform detailed modeling to determine risk impacts to specific receptors • Source test for actual toxic emissions • Tests showed high destruction of PAH across catalyst