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## MEMORANDUM

T O: Docket FROM: EPA, Air Quality Policy Divison SUBJECT: Ozone Contribution Analysis of Receptors in the Updated CSAPR Proposal DATE: March 10, 2016

T he attached spreadsheet file contains the ozone contributions from each state to each projected 2017 receptor site in the contiguous United St ates based on the modeling used for the, “Notice of Availability of the Environmental Protection Agency's Updated Ozone Transport Modeling Data for the 2008 Ozone NAAQS” 1 (NODA) and the proposed “Cross- State Air Pollution R ule Update for the 2008 Ozone NAAQS” 2 (CSAPR Update Rule)

. The data in the spreadsheet were derived from the contribution data used in the NODA and the CSAPR Update Rule. 3 For more information on the EPA’s 2008 ozone NAA QS interstate transport modeling analysis for the CSAPR Update Rule please see the Air Quality Modeling Technical Support Document that could be found at this link and the docket of this rulemaking: https://www.epa.gov/airmarkets/air

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Th e attached spreadsheet includes ozone contribution data for each ozone monitoring site that is projected to be a nonattainment site or maintenance-only sited based on the proposed CSAPR update rule. In addition, this spreadsheet contains aggregated contribution information including the sum of the contributions from all upwind states and the percent of total ozone from upwind states. The specific information in the spreadsheet is as follows: Column A contains the Monitor ID ; Column B contains the State where the monitor is located; Column C contains the County where the monitor is located; Column D contains the projected 2017 average design value for the monitor (ppb);

1 Notice of Availability of the Environmental Protection Agency's Updated Ozone Transport Modeling Data for the 2008 Ozone National Ambient Air Quality Standard (NAAQS), 80 FR 46271 (August 4, 2015). 2 See 80 FR 75706; December 3, 2015. 3 Note that the modeling and contribution data from the NODA and the CSAPR update rule are exactly the same.2 Column E contains the projected 2017 maximum design value for the monitor (ppb); Column F is blank; Columns G through BC contain the contributions from individual upwind states (ppb); Columns BD through BI contain the contributions (ppb) from the other source “tags” included in the contribution modeling (i.e. point source emissions on Tribal lands, emissions in Canada and Mexico, Offshore emissions, emiss ions from Fires, Boundary concentrations, and Biogenic emissions); note that red values indicate contributions at or above the 1% threshold; Column BJ is blank; Column BK contains the sum of contributions from all upwind states (ppb); Column BL contains th e contributions from the “home state” to ozone within that state (ppb); Column BM is blank; Column BN is the total ozone (ppb) which is the sum of all the contributions (equivalent to the 2017 average DV, before truncation of the contributions ); Column BO is percent of total ozone from all upwind states (i.e., column BK divided by column BN expressed as a percent); Column BP is the name of the downwind area containing the monitor, for those monitors with linked upwind states; and Column BQ indicates the na me(s) of the upwind state(s) linked to the monitoring site , for those sites in the We st; BQ contains the number of upwind states linked to the monitoring site , for those sites in the East.

## Contribution Analysis of Transport Receptors