OAR 340-245-0200
Risk Estimates

(1) When a risk assessment is required under this division, the risk assessment must consider the toxic air contaminants and the Risk-Based Concentrations listed in OAR 340-245-8040 (Table 4 - Risk-Based Concentrations) Table 4 to assess excess cancer and noncancer risk.
(2) Directions for the Level 1 Risk Assessment Tool.
(a) An owner or operator that chooses to perform a Level 1 Risk Assessment under OAR 340-245-0050 (Risk Assessment Procedures), must calculate a separate sum of risk ratios for each of the following categories: excess cancer risk, chronic noncancer risk, and acute noncancer risk for the applicable exposure locations;
(b) When making this calculation, the owner or operator must use the emissions inventory submitted under OAR 340-245-0040 (Emissions Inventory)(1) for:
(A) Excess cancer risk and chronic noncancer risk, the average annual emission rates; and
(B) Acute noncancer risk, the maximum daily emission rates.
(c) The owner or operator must perform each of the following calculations in paragraphs (A) and (B), except as allowed in paragraph (C):
(A) For excess cancer risk and chronic noncancer risk:
(i) For each TEU, use the stack height and distance to the nearest exposure locations to identify the appropriate dispersion factor under OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5A. If the TEU is a fugitive source, use the area and height of the building and distance to the nearest exposure locations to identify the appropriate dispersion factor under OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5C;
(ii) For each TEU and each toxic air contaminant emitted from the TEU, multiply the annual emission rate by the dispersion factor identified under subparagraph (i) to calculate an air concentration at the nearest exposure location;
(iii) For each TEU, divide the air concentration of each toxic air contaminant calculated under subparagraph (ii) by the appropriate RBC of that toxic air contaminant under OAR 340-245-8040 (Table 4 - Risk-Based Concentrations) Table 4;
(iv) For each TEU, add up the risk from each toxic air contaminant calculated under subparagraph (iii); and
(v) For all TEUs, add up all of the risks calculated under subparagraph (iv) to obtain the total excess cancer risk in one million or the total chronic noncancer Hazard Index for the entire source. For chronic noncancer risk, Hazard Indices may be calculated by noncancer target organ or organ systems in consultation with DEQ;
(vi) When an existing source emits a mixture of toxic air contaminants assigned noncancer TBACT Risk Action Levels of both a Hazard Index of 3 and a Hazard Index of 5 as identified in OAR 340-245-8030 (Table 3 - Toxicity Reference Values), Table 3 and OAR 240-245-8040, Table 4, the owner or operator must calculate a Risk Determination Ratio using the formula in section (5) of this rule.
(B) For acute noncancer risk:
(i) For each TEU, use the stack height and distance to the nearest exposure location to identify the appropriate dispersion factor under OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5B. If the TEU is a fugitive source, use the area and height of the building and distance to the nearest exposure locations to identify the appropriate dispersion factor under OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5D;
(ii) For each TEU and each toxic air contaminant emitted from the TEU, multiply the maximum daily emission rate by the dispersion factor identified under subparagraph (i) to calculate an air concentration at the nearest exposure location;
(iii) For each TEU, divide the air concentration of each toxic air contaminant calculated under subparagraph (ii) by the acute RBC for that toxic air contaminant under OAR 340-245-8040 (Table 4 - Risk-Based Concentrations) Table 4;
(iv) For each TEU, add up the risk from each toxic air contaminant calculated under subparagraph (iii); and
(v) For all TEUs, add up all of the risks calculated under subparagraph (iv) to obtain the total acute noncancer Hazard Index for the entire source. Hazard Indices may be calculated by noncancer target organ or organ systems in consultation with DEQ;
(vi) When an existing source emits a mixture of toxic air contaminants assigned noncancer TBACT Risk Action Levels of both a Hazard Index of 3 and a Hazard Index of 5 as identified in OAR 340-245-8030 (Table 3 - Toxicity Reference Values), Table 3 and OAR 340-245-8040 (Table 4 - Risk-Based Concentrations), Table 4, the owner or operator must calculate a Risk Determination Ratio using the formula in section (5) of this rule.
(C) Instead of using stack height and distance or area and height of the building and distance to the nearest exposure locations to obtain the appropriate dispersion factor under OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5, the owner or operator may instead use, as a default, the most conservative dispersion factor;
(i) For stack emissions, use the dispersion factor associated with a stack height of five meters and an exposure location distance of 50 meters, which is listed in the upper-left corner of OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5A and B;
(ii) For fugitive emissions, use the dispersion factor associated with an area of less than or equal to 3,000 square feet, a building height of less than or equal to 20 feet, and an exposure location distance of 50 meters, which is listed in the upper-left corner of OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5C and D; and
(iii) Using these default dispersion factors will result in protective calculations of risk. If the risks calculated using these default dispersion factors are less than or equal to the applicable Risk Action Levels, the owner or operator may choose to use the risks calculated in this manner to show compliance with the Source Risk Limits.
(3) Sum of Risk Ratios calculation procedure for Level 2, Level 3 and Level 4 Risk Assessments.
(a) An owner or operator that chooses to perform a Level 2, Level 3 or Level 4 Risk Assessment under OAR 340-245-0050 (Risk Assessment Procedures), must calculate a separate sum of risk ratio for each of the following risk categories: excess cancer risk, chronic noncancer risk, and acute noncancer risk for the applicable exposure locations;
(b) When making this calculation, the owner or operator must use the following modeled ambient concentrations for each toxic air contaminant at all exposure locations:
(A) For excess cancer risk and chronic noncancer risk, the annual average concentrations must be used; and
(B) For acute noncancer risk, the maximum daily concentrations must be used;
(c) The owner or operator must perform the following calculations for each of the risk categories listed in subsection (a) and using the concentrations in subsection (b):
(A) For each TEU, divide the modeled concentration of each toxic air contaminant by the appropriate RBC of that toxic air contaminant under OAR 340-245-8040 (Table 4 - Risk-Based Concentrations) Table 4, ensuring that the concentration is expressed in micrograms per cubic meter;
(B) For each TEU, add up the risk from each toxic air contaminant calculated under paragraph (A); and
(C) For all TEUs at each exposure location, add up all of the risks calculated under paragraph (B) to obtain the total excess cancer risk in one million, the total chronic noncancer Hazard Index, or the total acute noncancer Hazard Index for the entire source. For noncancer risk, Hazard Indices may be calculated by noncancer target organ or organ systems in consultation with DEQ.
(D) When an existing source emits a mixture of toxic air contaminants assigned noncancer TBACT Risk Action Levels of both a Hazard Index of 3 and a Hazard Index of 5 as identified in OAR 340-245-8030 (Table 3 - Toxicity Reference Values), Table 3 and OAR 340-245-8040 (Table 4 - Risk-Based Concentrations), Table 4, the owner or operator must calculate a Risk Determination Ratio using the formula in section (5) of this rule
(4) Significant figures and rounding. When a risk is calculated for comparison to a Risk Action Level or Source Risk Limit:
(a) The final risk calculation must be rounded off as follows:
(A) For comparison to the Aggregate TEU Level, Risk Determination Ratio, and the Source Permit Level, round off to one decimal place; and
(B) For comparison to other Risk Action Levels or Source Risk Limits, round off to a whole number;
(b) Round up if the last figure to be rounded off is 5 or greater, otherwise round down.
(c) Use of rounded numbers in making final risk calculations is not allowed. Only the final risk number may be rounded as described in this section.
(5) Calculating a Risk Determination Ratio. The formula for calculating a Risk Determination Ratio is:

Source: Rule 340-245-0200 — Risk Estimates, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=340-245-0200.

340‑245‑0005
Purpose and Overview 340‑245‑0010
Applicability and Jurisdiction 340‑245‑0020
Definitions 340‑245‑0022
Abbreviations and Acronyms 340‑245‑0030
Submittal and Payment Deadlines 340‑245‑0040
Emissions Inventory 340‑245‑0050
Risk Assessment Procedures 340‑245‑0060
Toxic Emissions Units 340‑245‑0100
Toxic Air Contaminant Permit Addenda 340‑245‑0110
Source Risk Limits 340‑245‑0120
Community Engagement 340‑245‑0130
Risk Reduction Plan Requirements 340‑245‑0140
Pollution Prevention 340‑245‑0150
Postponement of Risk Reduction 340‑245‑0200
Risk Estimates 340‑245‑0210
Modeling and Risk Assessment Work Plan Requirements 340‑245‑0220
TBACT and TLAER Procedures 340‑245‑0230
Toxic Air Contaminant Monitoring Requirements 340‑245‑0300
Toxicity Reference Values 340‑245‑0310
Process for Updating Lists of Regulated Toxic Air Contaminants and Their Risk-Based Concentrations 340‑245‑0320
Standards and Criteria for Noncancer Risk Action Levels for Existing Contamination Sources 340‑245‑0400
Cleaner Air Oregon Fees 340‑245‑8010
Table 1 - Risk Action Levels 340‑245‑8020
Table 2 - Toxic Air Contaminant Reporting List 340‑245‑8030
Table 3 - Toxicity Reference Values 340‑245‑8040
Table 4 - Risk-Based Concentrations 340‑245‑8050
Table 5 - Level 1 Risk Assessment Tool Dispersion Factors 340‑245‑9000
Colored Art Glass Manufacturing Facility Rules 340‑245‑9010
Colored Art Glass Manufacturing Facility Rules 340‑245‑9015
Colored Art Glass Manufacturing Facility Rules 340‑245‑9020
Colored Art Glass Manufacturing Facility Rules 340‑245‑9030
Colored Art Glass Manufacturing Facility Rules 340‑245‑9050
Colored Art Glass Manufacturing Facility Rules 340‑245‑9060
Colored Art Glass Manufacturing Facility Rules 340‑245‑9070
Colored Art Glass Manufacturing Facility Rules 340‑245‑9080
Colored Art Glass Manufacturing Facility Rules
Last Updated

Jun. 8, 2021

Rule 340-245-0200’s source at or​.us