From: Lydia Wegman/RTP/USEPA/US

To: "Frey, Nathan J." <Nathan_J._Frey@omb.eop.gov>, "Lee, Amanda I." 

<Amanda_I._Lee@omb.eop.gov>

Cc: Joseph-J Dougherty/DC/USEPA/US@EPA, Darryl Weatherhead/RTP/USEPA/US@EPA, Lillian 

Bradley/RTP/USEPA/US@EPA, Bryan Hubbell/RTP/USEPA/US@EPA

Date: 12/13/2012 06:08 PM

Subject: Responses to written interagency comments 

Nathan, 

We have made all the requested changes to the RIA identified in the written interagency comments. Our 

responses to the comments are contained in the attached document on pages 3 through 5.
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

Applicability of Microscale Monitors for Comparison to Annual PM NAAQS. 

Some commenters disagree with EPA’s final proposal to add language “that 

explicitly states that measuring PM2.5 in micro- and middle-scale environments near 

emissions of mobile sources, such as a highway, does not constitute being impacted 

by a “unique” source”(p. 553). As commenters noted on the NPRM, it is 

unreasonable to assume that no highways would represent a unique source. PM 

emissions resulting from a roadway are very unique to the individual characteristics 

of that roadway, such as fleet mix, age distribution, level-of-service, and road 

geometry. These commenters do not agree with EPA’s rational that “Mobile sources 

are rather ubiquitous and, as such, there are many locations throughout an urban 

area where elevated exposures could occur.(sic)” Not all highways, even those with 

similar levels of AADT, have the same vehicle activity patterns and characteristics, 

notably the amount of diesel vehicles. The commenters therefore disagree with 

EPA’s interpretation on the ubiquitous nature of all highways and requests 

maintaining the current capacity for unique sites to be able to be determined on a 

case-by-case basis without adding the explicit language that all highways are 

assumed to not be unique.

Any changes in the implementation for PSD permitting and transportation 

conformity should be consistent as related to the proposed change in the 

applicability of receptors for comparison to the annual standard. EPA noted in its 

response to interagency comments on the NPRM that: “...if the proposed PM NAAQS 

revisions and monitoring regulation clarifications described previously are 

finalized, permitting agencies will continue to have the flexibility to qualify or 

disqualify specific receptor locations used in PSD air quality analyses consistent 

with those provisions.” However, for transportation conformity the change “would 

mean that micro- and middle scale sites would be compared to the annual PM2.5 

standard unless the Regional Administrator decides that the site is unique.” EPA 

proposes to remove the flexibility in the current Transportation Conformity PM hotspot guidance for the interagency consultation process to determine whether 

receptors are appropriate for comparison to the annual NAAQS. Interagency 

commenters strongly object to this inconsistent approach and the removal of 

flexibility to transportation projects while the same flexibility will continue to be 

allowed for other permitting agencies and evaluation of other micro and middle 

scale sites. Inconsistencies in the application of the change in annual NAAQS 

receptor applicability should be resolved and transportation project sponsors 

should continue to have the flexibility to be able to qualify or disqualify specific 

receptor locations via the interagency consultation process.
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

Applicability of Near Road Monitor to the NAAQS. 

EPA proposed to finalize the institution of near road monitors for PM in CBSAs over 

1 million. Some commenters do not believe, particularly in the case of PM, that one 

near road monitor can represent area-wide exposures. Concentrations of PM in the 

near road environment are dependent on the nature of traffic on that roadway 

which can vary considerably with such factors as vehicle mix and age distribution. 

It does not appear that EPA has provided any research or other explicit justification 

to support the Agency’s decision such as information on the scalability of PM2.5 

monitoring results associated with one roadway to other roadways in the CBSA 

including the magnitude of sensitivity for a variety of variables such as AADT, fleet 

mix, fleet age distribution, road geometry, level-of-service, temporal distribution of 

VMT, site-specific meteorological conditions, and others. Commenters request that 

EPA please provide this justification. 

It is additionally inappropriate, particularly in the case of CO and PM, to collocated 

monitors to measure maximum concentrations of both pollutants. CO is a mobile 

pollutant driven primarily by gasoline vehicles and PM is driven primarily by diesel 

vehicles. EPA has sited research in Transportation Conformity Rule Amendments 

showing clustering of CO with gasoline vehicles and NOx, PM2.5, and PM2.5-10 with 

diesel vehicles (e.g., heavy-duty diesel trucks) the positive relationship of PM2.5

mass and elemental carbon mass (primarily from diesel exhaust), and 

concentrations of PM2.5 significantly associated with diesel vehicles on nearby 

roadways but not with gasoline vehicles (71 FR 12492). 

Interagency commenters request that EPA include a discussion in the preamble of 

the rule that describes how the change from a spatial averaging approach to a nearroad monitoring regime would affect future non-attainment implications. 

Secondary Standard

The Preamble and Regulatory Text is extremely confusing with regard to its 

discussion about secondary visibility issues. At first read it appeared that EPA was 

going to adopt its proposed visibility calculation (in deciviews), and it is not until 

after 100 or more pages that it became apparent that they felt the 15/35 standard 

was sufficient to address all visibility-related PM2.5 issues. This should be 

rewritten, with the conclusions stated up-front and throughout, without subjecting 

the reader to undue angst and confusion for many pages. 

On p. 484 of the preamble, EPA concludes that “the existing 24-hour PM2.5

[secondary] standard provides at least the target level of protection for visual air 

quality defined by a visibility index set at 30 dv, as described above, which the EPA 

judges appropriate.” It would be helpful if, in the discussion preceding this 
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

conclusion, EPA provided greater clarity and more explanation for its basis to 

determine that a distinct secondary standard for PM2.5 defined in terms of a PM2.5

visibility index is not needed. In the section of the preamble discussing the 

secondary standard, there are 40+ pages of background and historical information, 

and several more pages of discussion about the basis for the Administrator’s 

proposed conclusions, but it is difficult to identify a clear articulation of EPA’s basis 

for its final decision that the current secondary 24-hour PM2.5 standard of 35 μg/m3

is sufficiently protective of visual air quality. We suggest EPA provide that clear 

articulation, especially given that the proposed rule concluded otherwise.

Exceptional Events 

As wildfire is a widespread and prevalent exceptional event source in 2010-2012, 

the time period for exclusion of data is likely too short to meet the designation 

deadline. EPA should consider not only prioritizing areas as stated on page 538 but 

should actively screen large wildfire influenced events in order to meet the 

designation deadline and to insure that these impacts are appropriately addressed 

during the designation process as there is an overwhelming wildfire load during 

2010-2012 and there is a huge cost to states to conduct the documentation for so 

many events. With the dramatic wildfire activity during the monitoring period 

coupled with the significant cost of exceptional event documentation ($30,000 to 

$250,000 per day of documentation reported by WESTAR), the potential for 

inclusion of wildfire influenced data is very high. This inclusion and potential 

inappropriate designation are a direct impediment and added cost to conducting 

prescribed fire in critical areas across the US and could slow Administration efforts 

to expedite forest restoration as well as increase risks to public and firefighter 

health and safety.

Regulatory Impact Analysis

The current description of “extrapolated costs” in the RIA’s Executive Summary and 

Chapter 7 are likely to leave a layperson with the impression that the controls for 

which estimates are generated (everything beyond “known controls”) are all 

technologies that do not yet exist. If that is not necessarily the case – if, for example, 

extrapolated costs also include the application of existing technologies in 

combinations and on sources that simply can’t be captured in the model or 

otherwise predicted or different strategies of emission reduction (rather than 

undiscovered end-of-pipe technologies) – EPA should provide additional 

clarification in both the Executive Summary and Chapter 7.

Made edits to Chapter 7 and the Exec Summary to clarify the use of 

extrapolated costs. Specifically, modified the language on pages 1 and 7 of 

Chapter 7 and on pages ES-9 and ES-15 of the Exec Summary.
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

In the Executive Summary and Chapter 3 of the RIA, EPA states that it remains 

appropriate to continue to use the Cross-State Air Pollution Rule (CSAPR) in the RIA 

baseline as a proxy for representing the emission reductions required by CAIR for 

the purposes of the rulemaking's modeling projections for 2020. In Chapter 3, EPA 

states, “This determination is based on the similarity in emission reductions 

associated with CSAPR and CAIR, and, furthermore for SO2, the inclusion of MATS in 

the RIA baseline.” It would be helpful if EPA can provide a more complete 

explanation of the “similarity in emission reductions associated with CSAPR and 

CAIR” and, most importantly, whether and how the inclusion of MATS in the RIA 

baseline helps to moderate the actual impact of the D.C. Circuit’s ruling on projected 

SO2/PM power sector emissions.

Made edits to Chapter 3 to include a reference for the CSAPR/CAIR 

comparison and further detail on the impact of MATS.

In the RIA chapter 2, pages 2-9 through 2-10 there is inconsistency between the 

periods shown in the figures (2003-2007) and that described in the text (2006-

2008, 2004-2008).

Made edits to indicate that the time periods should all indicate 2006-2008..

Page 3-5: 

Recommend providing a brief discussion about why EPA is using the 2008 NEI - is 

this the most recent NEI available?

Added a sentence indicating that the 2008 NEI v2 is the most recently 

available NEI. The next NEI will be developed for 2011. Data collection for the 

2011 NEI is ongoing through the end of 2012, with the inventory due to be 

published in 2013.

Page 3-6: 

Recommend reversing the order of the sentences in paragraph 2 and making a few 

minor edits, so that it would read something like: "Because of the similarity in 

emissions reductions associated with CSAPR and CAIR . . . EPA has determined that 

it remains appropriate that CSAPR continue to be used in the RIA baseline as a proxy 

for representing the emission reductions required by CAIR . . ."

Revised paragraph.

Because the previous sentence states that it is appropriate to rely on CAIR 

reductions following the court decision, it is confusing to then say that EPA will rely 

on CSAPR in the modeling without first explaining that EPA believes the emissions 

reductions to be roughly similar for both rules. 
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

Revised paragraph.

The phrase "and, furthermore for SO2, the inclusion of MATS in the RIA baseline" is 

confusing - recommend clarifying. 

Added additional detail on the impact of MATS on SO2.

Page 3-7

The term "CAFE" should not have an accent.

Revised.

Change "published" to "issued" in the statement about the date the CAFE rule was 

signed. 

Revised.

Page 3-10

Recommend using consistent terminology for the GHG/FE rules - the list of onroad 

mobile controls uses "GHG rules" for the 2012-2016 LD rule and for the HD rule, but 

CAFE for the 2008-2011 rule. Since the other rules were also FE rules, suggest 

adding that language to those rules as well to avoid confusion.

Revised.