Box 2460, Hamilton Ontario, L8N 3J5 Phone: (905) 548-7200 ext. 3498 Fax: (905) 548-4200

June 2020

Emission Summary & Dispersion Modeling Report: Executive Summary ArcelorMittal Dofasco Facility, Hamilton, Ontario

ArcelorMittal Dofasco G.P. (Dofasco) operates an integrated steel mill located at 1330 Burlington Street East in Hamilton, Ontario (the Facility). The Facility takes coal, iron ore, scrap steel, and fluxes, to produce more than 4 million tons of flat rolled and tubular steel products per year. Major customers include the automotive, construction, energy, manufacturing, pipe and tube, appliance, container, and steel distribution industries. As of current operations, the Facility includes two coke plants, three blast furnaces, a KOBM basic oxygen furnace and an electric arc furnace in the steelmaking plant, two slab casters, a hot strip rolling mill, cold mills, annealing furnaces, galvanizing lines, an electrolytic coating line and two tube mills. Approximately 5,000 people work at the Facility. The Facility was constructed prior to November 30, 2005 and the North American Industrial Classification System (NAICS) code that best describes its primary operations is 331110 – Iron and Steel Mills and FerroAlloy Manufacturing. The Facility was phased-in under Schedule 4 of Ontario Regulation (O.Reg. 419/05) and must have an Emission Summary and Dispersion Modelling (ESDM) Report in place in accordance with s.26 of the regulation. This ESDM report was completed to demonstrate ongoing compliance with the Limited Operational Flexibility (LOF) contained within the Environmental Compliance Approval (Air and Noise) that has been issued to the site (Ref. 1982-AZAJ4W). This ESDM Report meets the requirement of O.Reg. 419/05 and has been prepared using the Ontario Ministry of Environment, Conservation and Parks (MECP) publication: “Procedure for Preparing an Emission Summary and Dispersion Modelling Report”, dated March 2018 (ESDM Procedure Document). The maximum point of impingement (POI) concentrations were calculated based on the operating conditions where significant sources were operating simultaneously at their maximum rate of production for the averaging time. The exception to this is where physical or operational limitations exist, which would exclude two pieces of equipment from operating simultaneously. The maximum emission rates for each significant compound emitted from the significant sources were calculated in accordance with s.11 of O.Reg. 419/05 and the data quality assessment follows the process outlined in the ESDM Procedure Document. A maximum POI concentration for each significant contaminant emitted from the Facility was determined based on these conservative emission rates and the US EPA AERMOD dispersion model; the results are presented in the following Emission Summary Table. The Facility has site-specific standards (SSS) for four compounds. The POI concentrations listed in the Emission Summary Table were compared against the SSS where applicable. The remaining compounds released were compared to the O.Reg. 419/05 limits that apply to the Facility, as listed in the MECP’s

publication “Air Contaminants Benchmark List: Standards, guidelines and screening levels for assessing point of impingement concentrations of air contaminants, Version 2.0” dated April, 2018 [List of Ministry POI Limits and Screening Levels]. This ESDM includes consideration of all action plans previously developed by the Facility for these existing site-specific standards. The assessment of the site’s compliance with the MECP’s air quality criteria yields the following:

 The majority of compounds have MECP POI limits and are predicted to be below the respective limits (including Schedule 3 standards and MECP guideline criteria).

 Four (4) compounds (i.e., benzene, benzo(a)pyrene, total suspended particulate, manganese) are predicted to be below the Site Specific Standards approved by the MECP for the site.

 Multiple compounds have been considered negligible through dispersion modelling because they are below 1% of their MECP POI Limits, JSL values or the MECP’s de minimus limit. These compounds are presented as an Appendix to this ESDM Report.

 Three (3) compounds (e.g. sodium) do not have MECP POI limits and are predicted to be below MECP approved maximum ground level concentrations approved under ECA No. 1982-AZAJ4W dated December 19, 2018. Details on the significant compounds are presented in the following Emission Summary Table. In accordance with the requirements of the Limited Operational Flexibility under the Environmental Compliance Approval issued to the site, Dofasco maintains a log that describes modifications to the Facility.

Emission Summary Table

Total Facility Maximum POI Averaging Emission Rate Air Dispersion Concentration MECP POI Percentage of Contaminant CAS No. (1) Category Period [hours] [g/s] Model Used [µg/m³] Limit [µg/m³] MECP Limit [%]

2019 Actual 2019 Actual

Titanium dioxide 13463-67-7 24 0.109 AERMOD 0.368 34 B1 1.1% Triethanolamine 102-71-6 24 0.007 AERMOD 0.321 27 B2 1.2% Thallium 7440-28-0 24 0.002 AERMOD 0.006 0.5 B2 1.2% Vanadium 7440-62-2 24 0.006 AERMOD 0.025 2 B1 1.3% MINERAL SPIRITS 64475-85-0 24 1.764 AERMOD 24.808 1750 B2 1.4% Tin 7440-31-5 24 0.008 AERMOD 0.192 10 B1 1.9% Beryllium 7440-41-7 24 0.0001 AERMOD 0.0002 0.01 B1 2.2% Butyl Cellosolve 111-76-2 10 min 0.015 AERMOD 11.468 500 B1 2.3% Boric acid 10043-35-3 24 0.019 AERMOD 0.834 33 B1 2.5% Hydrogen cyanide 74-90-8 24 0.022 AERMOD 0.298 8 B1 3.7% Vinyl Toluene 25013-15-4 24 0.230 AERMOD 62.969 1210 B2 5.2% Sodium sulfate 7757-82-6 24 0.019 AERMOD 0.834 15 B2 5.6% Aluminum oxide 1344-28-1 24 1.250 AERMOD 6.702 120 B1 5.6% Nickel 7440-02-0 Annual 0.004 AERMOD 0.002 0.04 B1 6.0% Ethylene 74-85-1 24 0.584 AERMOD 2.409 40 B1 6.0% Chromium (VI) 18540-29-9 24 0.0004 AERMOD 0.0047 0.07 DAV 6.7% Naphthalene 91-20-3 10 min 0.130 AERMOD 3.375 50 B1 6.7% Sodium hydroxide 1310-73-2 24 0.037 AERMOD 0.738 10 B1 7.4% Zinc 7440-66-6 24 1.519 AERMOD 9.169 120 B1 7.6% Lead 7439-92-1 30 day 0.044 AERMOD 0.019 0.2 B1 9.6% Magnesium oxide 1309-48-4 24 1.875 AERMOD 11.629 120 B1 9.7% Potassium 7440-09-7 24 0.070 AERMOD 0.097 1 B2 9.7% Lead 7439-92-1 24 0.044 AERMOD 0.050 0.5 B1 10.0% Phenol 108-95-2 24 0.126 AERMOD 3.104 30 B1 10.3% Cadmium 7440-43-9 24 0.002 AERMOD 0.003 0.025 B1 10.4% Naphthalene 91-20-3 24 0.130 AERMOD 2.755 22.5 B1 12.2% 1,3,5-Hexahydro-S-Triazine 121-82-4 24 0.007 AERMOD 0.321 2.5 B2 12.8% Calcium oxide 1305-78-8 24 0.218 AERMOD 1.397 10 B1 14.0% Hydroquinone 123-31-9 24 0.006 AERMOD 1.710 10 B2 17.1% Hydrochloric Acid 7647-01-0 24 0.943 AERMOD 3.507 20 B1 17.5% Calcium hydroxide 1305-62-0 24 0.356 AERMOD 2.402 13.5 B1 17.8% Silicon Dioxide 14808-60-7 24 0.411 AERMOD 1.039 5 B1 20.8% Phosphorus Pentoxide 1314-56-3 24 0.063 AERMOD 0.238 1 B2 23.8% Chromium (VI) 18540-29-9 24 Annual 0.0004 AERMOD 0.0004 0.0014 AAV 26.1% Ammonia 7664-41-7 24 1.996 AERMOD 31.031 100 B1 31.0% Chromium (TOTAL) 7440-47-3 24 0.016 AERMOD 0.156 0.5 B1 31.2%

June 2020

Emission Summary Table Total Facility Emission Maximum POI Averaging Rate Air Dispersion Concentration MECP POI Percentage of Contaminant CAS No. (1) Category Period [hours] [g/s] Model Used [µg/m³] Limit [µg/m³] MECP Limit [%]

2019 Actual 2019 Actual Dicalcium silicate N/A-3 24 2.864 AERMOD 15.242 40.5 Site Specific Level 37.6% Total Reduced Sulfur N/A-2 24 1.478 AERMOD 3.150 7 B1 45.0% Ferric oxide 1309-37-1 24 7.315 AERMOD 13.510 25 B1 54.0% Thiocyanate 81210-01-7 24 0.118 AERMOD 2.618 4.72 Site Specific Level 55.5% Benzo[a]Pyrene 50-32-8 Annual 0.002 AERMOD 0.010 0.017 Site Specific Standard 55.9% Total Suspended Particles N/A-1 24 61.909 AERMOD 101.108 177 Site Specific Standard 57.1% DIOXIN FURAN N/A-4 24 0.00000005 AERMOD 0.00000006 0.0000001 B1 60.2% Manganese 7439-96-5 24 0.300 AERMOD 0.944 1.5 Site Specfic Standard 62.9% Nitrogen oxides 10102-44-0 24 187.441 AERMOD 132.077 200 B1 66.0% Carbon monoxide 630-08-0 30 min 931.967 AERMOD 4030.172 6000 B1 67.2% Sodium 7440-23-5 24 0.442 AERMOD 0.470 0.676 Site Specific Level 69.6% Chromium (VI) 18540-29-9 Annual 0.0003 AERMOD 0.0001 0.00014 B1 77.1% Benzene 71-43-2 Annual 1.553 AERMOD 9.012 11.1 Site Specific Standard 81.2% Sulfur dioxide 7446-09-5 1 522.155 AERMOD 576.601 690 B1 83.6% Nitrogen oxides 10102-44-0 1 189.130 AERMOD 340.491 400 B1 85.1% Sulfur dioxide 7446-09-5 24 522.151 AERMOD 235.100 275 B1 85.5% Total Reduced Sulfur N/A-2 10 min 1.463 AERMOD 12.197 13 B1 93.8% Calcium carbonate 471-34-1 24 2.149 AERMOD 14.705 15 B2 98.0% Notes: Site specific level - reviewed and approved by the MECP in the 2009 ESDM submitted in support of ECA with LOF for the site. (1) In accordance with MECP guidelines, 10-minute POI concentrations modelled at nearest sensitive receptor.

June 2020