Air Toxics & Modeling

1. Air Toxics & Modeling Kentucky Division for Air Quality Taimur Shaikh Ph.D.

2. Introduction Air Toxics Implementation • Ambient Sampling • Modeling • Risk Assessment • Air Toxics Modeling • Scope • Sample Projects • Various Toxics Modeled Facilities • Pb NAAQS Modeled Facility

3. Air Toxics Implementation

4. 401 KAR 63:020 • Potentially hazardous matter or toxic substances regulation “No owner or operator shall allow any affected facility to emit potentially hazardous matter or toxic substances in such quantities or duration as to be harmful to the health and welfare of humans, animals and plants.”

5. Ambient Sampling VOC’s EPA Method TO-15 Analyze for volatile organics Both grab and 24-hour composite samples SVOC’s EPA Method TO-13A Analyze for Poly-Aromatic Hydrocarbons 24-hour composites samples • Metals/Metalloids (Future) • PM10 including metals speciation • 24-hour (or greater) composite samples

6. Air Toxics Modeling • Consists of multiple tiers • 1st tier – Screening via Screen3, conducted by permit reviewers • 2nd tier – AERMOD modeling using pertinent meteorological data and LULC data • 3rd tier – Same as 2nd tier but can require validated stack test emission rates, mass balances, and other data • Usually performed: • For new facilities/major modifications • In addition to sampled data • As a follow-up to citizen complaints

7. ATRA Reference Library As part of the interpretation of 401 KAR 63:020, the Division uses EPA’s Air Toxics Risk Assessment (ATRA) Reference Library Volumes I, II, and III as the procedural direction for conducting risk evaluations. • http://www.epa.gov/ttn/fera/risk_atra_main.html

8. Risk Assessment • Air Toxics Reference Library (ATRA) • “Tiered” Risk Assessment • Three distinct tiers • The higher tiered assessments involve more complexity and have more rigorous data requirements • 1st tier – Risk is based on Screen3 output • 2nd tier – Risk is based on annual average from AERMOD (chronic assessment) • 3rd tier – Risk is based on ambient sampling data in addition to modeled values, at impacted individual, includes a more complex exposure and toxicity assessment • Based on EPA guidance documents • Most often, the data requirements limits the scope of the assessment

9. The Tiered Risk Assessment Complete study-specific data, no assumptions - higher cost, lower uncertainty Add quantitative uncertainty / variability analysis More refined exposure assessment More refined dispersion & exposure modeling Simple dispersion model Lookup Table MORE REFINED Tiers 2 & 3 SCREENING Tier 1 No data, all assumptions - lower cost, high uncertainty

10. The Tiered Risk Assessment Tier 1 (Screening Level) Tier 2 (Moderate Complexity) • Lookup tables • Exposure = maximum offsite levels • Simple dispersion modeling (MEI) • No data – all assumptions • Lower cost – high uncertainty • Conservative results – consistently over-estimates risk • Exposure = exposure assessment • Detailed site-specific modeling (MIR) • Complete study-specific data • No assumptions • Higher cost – lower uncertainty • Exposure = residential air levels • More refined dispersion & exposure modeling (MIR) • Moderate cost Tier 3 (High Complexity)

11. Air Toxics Domain • All higher-level (tiers 2 & 3) risk assessments • As directed by DAQ Management, risk assessments involving: • Unlisted pollutants • Acute health effects • Bioaccumulation • Cumulative risk • Carcinogenic risk • Target organ specific hazard index • Emissions from multiple sources • Environmental damage

12. Air Dispersion Modeling

13. Sample Projects • Examples of incorporating modeling into Air Toxics: • Toxics analysis – Dioxins & Furans • Toxics analysis – Hydrazine • Toxics analysis – HF modeling under 401 KAR 53:010 • Modeling that belongs to Air Toxics by managerial default: • NSR/PSD review • Site evaluation of monitors for the Pb NAAQS.

14. Toxics Analysis – Dioxins & Furans • Secondary Aluminum Smelter • Emissions of Dioxin and Furans covered under Subpart RRR – NESHAP for Secondary Aluminum Production • Facility could not demonstrate capture efficiency due to deviations from RRR • Modeled annual average (4.3*10-7 g/m3) exceeds 1*10-6 carcinogenic risk (6.4*10-8 g/m3) • The facility is operational at the moment but has taken a production limit

15. Secondary Al Smelter(Dioxin 1 Hour Average)

16. Secondary Al Smelter(Dioxin Annual Average)

17. Toxics Analysis – Hydrazine • A specialty chemical facility manufacturing organic and organometallic compounds • The facility was permitted to emit Ni, Cd, Pb, and hydrazine • After initial modeling with AERMOD, modeled ambient concentrations exceeded 1:1,000,000 carcinogenic risk with cadmium driving the risk at 1:1,000 • After our investigation, the facility choose to remove Cd, and Ni and reduce Pb and hydrazine emissions

18. Specialty Chemical Facility (Hydrazine Annual Average, Pre-reduction)

19. Specialty Chemical Facility (Hydrazine Annual Average, Post-reduction)

20. Toxics Analysis - HF • 401 KAR 53:010 is the Kentucky Ambient Air Quality Standards which include standards for HF • These are not to be exceeded more than once per year • A ceramic and tile manufacturing facility was modeled to show compliance

21. Ceramic Manufacturer(HF 12 Hour Average)

22. Ceramic Manufacturer(HF 24 Hour Average)

23. Pb NAAQS • The modeling was used in site selection criteria for a Pb monitor in conjunction with the new Pb National Ambient Air Quality Standard (10/15/2008)

24. Pb From a Coal Fired Power Plant • Used air dispersion modeling of a coal fired power plant to site a monitor for the Pb NAAQS • The NAAQS is based on a 3-month rolling and quarterly average • Compared the one month and annual averages to choose the site for the monitor

25. Coal Fired Power Plant(Pb Month Average)

26. Coal Fired Power Plant(Pb Annual Average)

27. Conclusions • Air dispersion modeling: • Features prominently in the KY Air Toxics strategy • Is applied in situations where monitoring is not feasible due to cost or time involved • Can be binding from a regulatory standpoint • Yields useful information for risk assessment

28. Questions? Dr. Taimur Shaikh - Taimur.Shaikh@KY.gov Kentucky Division for Air Quality – (502)564-3999 ext. 4480