Re: Fw: Texas's comments regarding the proposed new NAAQS for ozone 

Phil Lorang to: matthew.johnston 07/09/2010 03:03 PM

Cc: Dave Mckee

Bcc: Benjamin Wells, David Mintz, Karen Martin, Susan Stone

Mr. Johnson,

This is in reply to your message to Dave McKee of EPA on July 8, 2010. Thank you for your 

message.

First, let me say that this e-mail is an unofficial response intended to increase your 

understanding of the proposal rather than to inform you of a final EPA decision or its rationale. 

The final rule is still in the future. Also, please be aware that a copy of this e-mail will be placed 

in the public docket for this rulemaking.

Your message asked the following two questions.

1. The TCEQ takes issue with the proposed language in Appendix P to part 50 stating that EPA 

shall use all valid ozone data "submitted to EPA's Air Quality System (AQS), or otherwise 

available to EPA" in calculating design values. Federal Register Vol. 75, No. 11, January 19, 

2010, p. 3049. To what does the phrase "otherwise available" refer? Is it meant to cover 

PAMS? Is there state-collected data that is not submitted to the AQS for some reason? 

Basically, how is EPA limited in what data can be used to calculate design values, and how is 

data from sources other than AQS verified?

Response:

The full text of the passage in the proposed rule regarding data to be used to calculated design 

values is quoted just below. 

"All valid FRM/FEM ozone data

submitted to EPA’s Air Quality System

(AQS), or otherwise available to EPA,

meeting the requirements of part 58 of this

chapter including appendices A, C, and E

shall be used in design value calculations."

Appendix A has QA program requirements. Appendix C says that data must have been 

collected using standardized, EPA-approved "reference/equivalent methods" (here, "method" 

essentially means the monitoring equipment). Appendix E addresses issues such as the 

distance between the monitor and nearby trees, buildings, and exhaust vents. If and when 

there are non-AQS data that are "otherwise available", whether that data meet these 

requirements will be an issue that EPA would have to address on a case-by-case basis.

This proposal was intended to address a possible situation that could arise in which the public 

record before EPA includes data that is relevant to calculation of design values and which EPA 

concludes meets the requirements of the three Appendices, but which have not been submitted 

to AQS, for whatever reason. We are inserting a provision to this effect into all the data 

interpretation Appendices to part 50 as they come up for revision as a result of reviews of the 

respective NAAQS, as a transparency improvement to properly inform states and others that 
this is the policy that we believe we would be constrained to follow if this type of situation ever 

arises. You will see similar provisions in Appendices R, S, and T. Basically, we believe that 

ignoring such data merely because it did not get submitted to a particular electronic data base 

would leave us vulnerable to a charge of having been arbitrary and capricious, because the 

mere fact of submission or non-submission is not material to the finding that we would be 

making regarding whether the air quality actually meets or does not meet the NAAQS.

The proposal does not define "otherwise available", so whether certain data were otherwise 

available would also have to be determined on a case-by-case basis. EPA did not assert in the 

proposal that there are at present any "otherwise available" ozone data that meet the 

requirements of the three Appendices, but there could be some day. Certainly, EPA would not 

use data that we had not put into the public docket in some manner so that all interested parties 

would have access to it. 

The following bullets address some types of ozone monitoring that you may hear about from 

others. 

z An EPA contractor operates a number of ozone stations as part of the Clean Air Status and 

Trends Network (CASTNET, see http://www.epa.gov/castnet/index.html). Ozone data from 

CASTNET are not at presented claimed by EPA to meet the requirements of the three 

Appendices, and these contractor-collected CASTNET ozone data is not being put into 

AQS. When CASTNET's QA practices do start to meet the requirements of the three 

Appendices, subsequent CASTNET ozone data will be submitted to AQS. Texas hosts two 

such sites, in Armstrong and Hardin Counties. 

z The National Park Service runs an ozone monitoring network. This NPS network includes 

some CASTNET sites at which the EPA contractor does not operate an ozone monitor. NPS 

sites meet the requirements of the three Appendices. It presently submits its ozone data to 

AQS, and EPA presently uses those data to calculate design values for those locations. 

There is only one NPS ozone monitoring site in Texas, in Big Bend National Park. 

z "PAMS" refers to photochemical assessment monitoring stations. These state-operated 

stations collect data on ozone precursors and ozone itself. Both types of data typically are 

submitted to AQS.

We have heard anecdotally that there are some state-collected data that are not submitted to 

the AQS, particularly from sites that are not required by EPA regulations, are not funded by EPA 

grants, do not use standardized "reference/equivalent methods", do not follow normal QA 

procedures, and/or do not operate for a long period. If a monitoring site does not operate for a 

three-year period or does not meet the requirements of the three Appendices, it cannot be used 

to determine attainment with the NAAQS anyway. This may mean that most or all of any data 

that has not been submitted to AQS cannot be used to determine attainment, regardless of the 

submission issue itself. I do not recall whether any of these anecdotes involved Texas. I would 

like to note that opinions may differ as to whether non-submission is consistent with EPA rules, 

because the wording of the EPA rules on data submission is open to some interpretation.

2. The TCEQ also claims that it would be overly burdensome for states to be required to 

maintain data used for calculations of eight-hour averages and three-year ozone values to the 

last decimal place that the calculation software can handle. They recommend assigning a cutoff 

point: six decimal places, for example. Are they merely being nit-picky here, or is there a 

genuine dispute as to the benefit/burden balancing involved in data retention? I was unable to 

find where EPA proposed this requirement, so I am unclear not only on the reasoning, but on 

what the actual proposal is (as opposed to TCEQ's characterization of it).
Response:

The intention of the proposal with regard to rounding/truncation issues was to avoid the 

systematic downward bias in the design value caused by the repeated truncation at the 

intermediate step of averaging 8 hourly concentrations and the final step of averaging three 

8-hour average concentrations from three years.

 I believe TCEQ is referring to its perception of the aggregate effect of the following proposed 

passages in Appendix P:

z In section 2(c) - "Hourly average concentrations shall be reported in parts per million (ppm) 

to the third decimal place, with additional digits to the right of the third decimal place 

truncated."

z In section 3(a) - "The computed 8-hour average ozone concentrations are not rounded or 

truncated."

z In section 3(c) - "The computed 3-year average of the annual fourth-highest daily maximum 

8-hour average ozone concentrations shall be rounded to three decimal places. Values 

equal to or greater than 0.xxx5 ppm shall round up."

z In Example 1 in section 3(e)(ii) - "In Example 1, the individual 8-hour averages and the 

3-year average are shown with six decimal digits. In actual calculations, all digits supported 

by the calculator or calculation software must be retained."

z In Example 2 in section 3(e)(ii) - "In Example 2, the individual 8-hour averages and the 

3-year average are shown with six decimal digits. In actual calculations, all digits supported 

by the calculator or calculation software must be retained."

z In Example 3 in section 4(a) - "In Example 3, the individual weighted concentrations and 

their sum are shown with six decimal digits. In actual calculations, all digits supported by the 

calculator or calculation software must be retained."

z In section 4(a) - "The computed 3-year average of the annual maximum consecutive 

3-month sum of adjusted monthly W126 index values in ppm-hours shall be rounded to a 

whole number with decimal values equal to or greater than 0.500 rounding up."

TCEQ appears to be concerned not about the elimination of the systematic downward bias, but 

only about data storage issues. As a formal matter, these are instructions for how to calculate a 

design value, not how to store data. In concept, only hourly ozone data needs to be stored, 

since all other results can be calculated when necessary, and the proposal clearly says that 

hourly ozone data is stored with only three decimal places. Also as a formal matter, there is no 

EPA mandate for TCEQ to store its own ozone data; AQS provides that service. Realistically, 

however, state agencies do store their own data and they naturally want to be consistent with 

how AQS works, to avoid confusion. AQS presently does store 8-hour averages. Because the 

pre-existing version of Appendix P says that 8-hour averages are to be truncated to three digits, 

AQS stores them with three digits. To meet the intention of the proposal to eliminate systematic 

downward bias, more digits clearly need to be stored but not a great many more. Therefore, the 

number of digits needed for storage purposes is a genuine issue for comment. Also, if a 

W126-based secondary ozone NAAQS is adopted it will likely store daily and/or monthly W126 

index values. These values need to be stored with a reasonable number of digits, but possibly 

not all the digits that are generated by the software calculates them. Therefore, we recognize 

that TCEQ has raised a valid practical issue with the proposal and we are reconsidering this 

aspect of the proposal.

Phil Lorang, Group Leader

Air Quality Analysis Group, AQAD, OAQPS, EPA
919-541-5463

Dave Mckee Phil, Since these questions deal with Appen... 07/08/2010 11:03:26 AM

From: Dave Mckee/RTP/USEPA/US

To: Phil Lorang/RTP/USEPA/US

Cc: Karen Martin/RTP/USEPA/US, Susan Stone/RTP/USEPA/US

Date: 07/08/2010 11:03 AM

Subject: Fw: Texas's comments regarding the proposed new NAAQS for ozone

Phil,

 Since these questions deal with Appendix P and rounding, I thought it would be best to pass 

this on to you. Thanks.

 Dave

Texas's comments regarding the proposed new NAAQS for ozone

Matthew Johnston to: Dave Mckee 07/08/2010 10:52 AM

Hello, Mr. McKee,

I am a legislative aide to Texas State Representative Lon Burnam, who serves on the House 

Environmental Regulation Committee. I am gathering information regarding the comment letter 

the Texas Commission on Environmental Quality submitted to EPA in response to the January 

19 proposed rulemaking lowering the NAAQS for ozone. I have been sifting through the 

proposed rulemaking in the Federal Register and the July 2007 OAQPS Staff Paper on which it 

is largely based. I contacted Holly Stallworth, Designated Federal Officer at CASAC, and she 

referred me to you. I hope you might clarify a couple of EPA's positions in light of the TCEQ's 

comments.

The TCEQ takes issue with the proposed language in Appendix P to part 50 stating that EPA 
shall use all valid ozone data "submitted to EPA's Air Quality System (AQS), or otherwise 

available to EPA" in calculating design values. Federal Register Vol. 75, No. 11, January 19, 

2010, p. 3049. To what does the phrase "otherwise available" refer? Is it meant to cover 

PAMS? Is there state-collected data that is not submitted to the AQS for some reason? 

Basically, how is EPA limited in what data can be used to calculate design values, and how is 

data from sources other than AQS verified?

The TCEQ also claims that it would be overly burdensome for states to be required to maintain 

data used for calculations of eight-hour averages and three-year ozone values to the last decimal 

place that the calculation software can handle. They recommend assigning a cutoff point: six 

decimal places, for example. Are they merely being nit-picky here, or is there a genuine dispute 

as to the benefit/burden balancing involved in data retention? I was unable to find where EPA 

proposed this requirement, so I am unclear not only on the reasoning, but on what the actual 

proposal is (as opposed to TCEQ's characterization of it).

Thank you much for your time and consideration.

Best regards,

Matt Johnston

Legislative Aide

Office of State Representative Lon Burnam

(512) 463-0740

matthew.johnston@house.state.tx.us