1 

MEMORANDUM 

TO: Docket

FROM: EPA, Air Quality Policy Divison

SUBJECT: Ozone Contribution Analysis of Receptors in the Updated CSAPR Proposal 

DATE: March 10, 2016 

The attached spreadsheet file contains the ozone contributions from each state to each projected 

2017 receptor site in the contiguous United States 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 Rule 

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 NAAQS 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-quality-modeling-technical-support-document-2008-ozonenaaqs-cross-state-air. 

The 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, emissions 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 the 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 name(s) of the upwind state(s) linked to the monitoring site, for 

those sites in the West; BQ contains the number of upwind states linked to the monitoring 

site, for those sites in the East. 
Contribution Analysis of Transport Receptors