From: Lydia Wegman/RTP/USEPA/US

To: nfrey@omb.eop.gov

Cc: James Hemby/RTP/USEPA/US@EPA, Michael Ling/RTP/USEPA/US@EPA, Peter 

Keller/RTP/USEPA/US@EPA, Lewis Weinstock/RTP/USEPA/US@EPA, Tim 

Hanley/RTP/USEPA/US@EPA, Joseph-J Dougherty/DC/USEPA/US@EPA, Anna 

Wood/RTP/USEPA/US@EPA, Richard Wayland/RTP/USEPA/US@EPA, Padmini 

Singh/DC/USEPA/US@EPA, Sara Schneeberg/DC/USEPA/US@EPA, Beth HassettSipple/RTP/USEPA/US@EPA, Scott Jenkins/RTP/USEPA/US@EPA, martin.karen@epa.gov

Date: 06/08/2012 08:50 AM

Subject: Responses to monitoring and implementation comments

Nathan, 

Attached are our responses to the monitoring and implementation comments we've received from the 

interagency group. We hope you can distribute them prior to our 1:30 meeting today. Please let me 

know if you have any questions. Thanks.
General Comments

Questions 1-3 are answered collectively below.

1) Attainment and Monitoring

EPA proposes to eliminate spatial averaging and "population-oriented" monitor 

placement, while mandating a near-road component to monitoring plans. Some 

commenters believe that these three provisions are internally inconsistent. Spatial 

averaging is a statistical means of expressing the 'ambient' aspect of "National 

Ambient Air Quality Standards." Averaging over the regulated area creates the 

regulatory consistency for the regional jurisdictions that is key to the regionallycontrolled implementation of the NAAQS. EPA cites the possibility of disparate 

health effects on disadvantaged populations as the reason for eliminating averaging.

However, EPA also proposes to eliminate "population-oriented" monitor placement, 

since EPA says that the concept of a monitor being population-oriented is 

incompatible with the 'ambient' nature of the NAAQS. In this provision, EPA 

dismisses linking NAAQS attainment to health effects as inconsistent with statute, 

even though the touchstone of the NAAQS standards is in fact public health.

2) Some commenters believe that EPA's reasoning for a near-road component to 

monitoring plans is inconsistent with its reasoning above. Near-road PM levels are 

not necessarily representative of actual risk to susceptible populations through 

exposure to PM. Nor is the placement of near-road monitors calculated to be a better 

proxy for health effects than "population-oriented" monitors. The elimination of 

spatial averaging and "population-oriented" monitors and the establishment of nearroad monitors can only have the effect of making NAAQS attainment more difficult.

3) Some commenters also note that the proposed PM standards and their impacts 

appear to be based on existing monitoring systems, such that the addition of nearroad monitors can increase the costs by putting additional areas into nonattainment 

without associated health benefits.

To clarify, we are not proposing to eliminate the establishment or regulatory 

use of population-oriented monitors. This is the very type of monitor that the 

agency agrees are essential to assessing compliance with any primary PM (or 

other criteria pollutant) standard -- monitoring sites that are representative 

of concentrations to which populations are potentially exposed. In fact, every 

currently operating PM2.5 site in the country and any sites being proposed in 

this rule are population-oriented by the existing definition and are therefore 

comparable to the PM standards. So, we are confident the change we are 
proposing (i.e., revocation of the requirement that PM2.5 monitoring sites be 

“population-oriented” for comparison to the NAAQS) will have effectively 

minimal if any practical impact. 

One of EPA’s goals with this proposed change is to provide consistency and 

predictability in the interpretation of monitoring regulations among all the 

NAAQS pollutants and eliminate the specific areas of confusion that have 

occurred in the past when EPA and the states review PM2.5 monitoring data. 

EPA certainly does not agree that a monitor being population-oriented is 

incompatible with the ambient nature of the NAAQS and if such a statement 

was made help us to identify it so that we can correct or clarify the statement. 

We agree the corner stone of the NAAQS standards is in fact public health.

Regarding the proposed near-road PM2.5 monitoring, EPA is proposing that all 

near-road monitors be sited in locations that are representative of other 

highly traffic road segments in a given CBSA. And since near-road 

environments occur throughout a metropolitan area, these monitors are 

therefore representative of concentrations to which the populations in these 

environments are exposed. As stated in the preamble, EPA also believes the 

near-road PM2.5 monitors will be useful for many monitoring objectives 

beyond comparison with the NAAQS. Near-road environments are 

complicated air quality locations that the Agency, in order to protect public 

health, is obligated to better understand. For example, the proposed 

requirements for the PM2.5 near-road monitors include co-location at near 

road stations with NO2 and CO monitors (stations which are soon to be 

deployed per previous final rules). Collectively, these measurements will be 

invaluable to understanding an important type of location that is ubiquitous 

throughout the country and in which a significant percentage of the American 

population lives and works. 

With respect to your comments on spatial averaging, as part of the 2006 

review, EPA tightened the criteria for use of spatial averaging to provide 

increased protection for vulnerable populations exposed to PM2.5. This change 

was based in part on an analysis of the potential for disproportionate impacts 

on potentially susceptible populations, which found that the highest 

concentrations in an area tend to be measured at monitors located in areas 

where the surrounding population is more likely to have lower education and 

income levels, and higher percentages of minority populations (71 FR 

61166/2, October 17, 2006; US EPA, 2005, section 5.3.6.1). In this review, as 

discussed in section III.B.3 of the preamble, based on additional health data, 
the Integrated Science Assessment has identified persons from lower 

socioeconomic strata as a susceptible population (US EPA, 2009a, section 

8.1.7; US EPA, 2011a, section 2.2.1). And as explained in the preamble, the 

proposed elimination provision is based on an analysis that indicates the existing

constraints on spatial averaging, as modified in 2006, may be inadequate to avoid 

substantially greater exposures in some areas, potentially resulting in 

disproportionate impacts on susceptible populations (Schmidt 2011a, Analysis A). 

In reviewing how spatial averaging is applied now, we note that no CBSA in the 

country has requested the use of spatial averaging since the criteria were 

revised in 2006.

While we may not fully understand your comment that the proposed near 

road requirements may increase costs with no associated health benefit, we 

do not agree that this is the case for two fundamental reasons. First, EPA has 

worked to design an implementation approach for the proposed near-road 

monitoring that is as cost effective as is feasible. Since we have proposed to 

focus of the near-road network in large CBSA’s (52 stations nationally 

representing CBSA’s over 1M in population), EPA believes that the PM2.5 

monitor requirement can be met by relocating existing sites rather than 

adding new sites. Further, because near-road monitoring stations are already 

required to be operational for CO and NO2, cost savings and operational 

efficiencies will be realized by locating PM2.5 instruments at the same site. 

Secondly, we simply do not know if the near-road monitors will result in any 

additional areas being designated nonattainment and will not until three 

years of valid data are collected and certified and these data work their way 

through the designation process. However, as explained in the preamble, 

there are lots of good reasons to collect these data. We do believe that the 

availability of these data will support many monitoring objectives including 

comparison to the NAAQS that would lead to health benefits.
4) Some commenters note that any difficulties in achieving attainment will likely 

translate into difficulties in PSD permitting. The elimination of spatial averaging, 

along with the inclusion of near-road monitors, is likely to make it more difficult to 

obtain permits. These commenters note that where EPA changes its interpretation 

about 'exclusion of some receptors' in PSD analyses, it does account for these 

changes and suggest that EPA clearly identify how these changes may or may not 

affect permitting decisions.

As we noted in the previous version of the NPRM, we do not expect any 

significant adverse PSD permitting impacts as a result of the proposed 

monitoring regulation clarifications. In order to resolve some confusion 

caused by the previous draft of the NPRM, we would recommend replacing the

text beginning at the first full paragraph on page 402. The draft revised 

language in the PSD section addressing this would read as follows: 

“In addition to the NAAQS revisions themselves, for which proposed and other 

possible implementation actions are described further below, the EPA is 

proposing certain clarifications to the existing monitoring regulations codified 

at 40 CFR 58.30 (Special considerations for data comparisons to the NAAQS). 

These proposed clarifications are presented in detail in section VIII.B.2 of this 

preamble. The monitoring regulations provide a basis for determining whether 

specific monitoring sites are comparable to specific NAAQS. By extension, EPA 

has used the principles of making these determinations for monitoring sites to 

also guide permitting authorities in assessing the comparability of specific 

receptor locations involved in PSD air quality analyses. Receptors are used in 

PSD modeling analyses to predict potential air quality impacts in the vicinity of 

the proposed new or modified facility and in some cases also at more distant 

Class I areas. The EPA will continue to use these principles in guiding PSD 

modeling analysis design. Accordingly, 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.”

We would then pick up at the last full paragraph on page 403 prior to 

subsection a.

23) Some commenters suggest that EPA should request comment whether it should 

move forward with the primary and secondary standards on the same timeline and 

on whether the designations must move forward in tandem. This is especially 
important given how different the visibility measure is from previous efforts and 

given that major rules affecting PM (GHG mobile sources and Boiler MACT) are not 

included in the baseline analysis and the significant work required in some states to 

comply with CSAPR-better-than-BART or state-specific consent decrees.

We understand the comment but note that this request is already made. The 

current designation section of the preamble describes the basic designations 

timeframe under the Act, in which designations commonly would be finalized 

by EPA within two years, but that EPA can take an additional year in the event 

there is "insufficient information" to complete the process in two years. We do 

point out that there could be good technical reasons (e.g. same sources 

contributing to both problems) to conduct designations for the primary and 

secondary PM2.5 NAAQS concurrently for areas that have adequate data. This 

approach could also result in certain implementation efficiencies for states 

down the road, in that implementation plans for both primary and secondary 

standards could be adopted and submitted on the same state rule adoption 

schedule. The section states that EPA remains flexible with regard to the 

designation schedule. Nevertheless, the section also concludes with the 

statement that "EPA invites preliminary comment on all aspects of the 

designation process at this time, which the Agency will consider in developing 

that guidance." We believe this section provides adequate opportunity for 

interested parties to provide comments on the designations process for the 

secondary standards.

24)Some commenters recommend that EPA should signal maximum flexibility in its 

enforcement of CAA timelines. For example, EPA has discretion to provide up to 2 1-

year extensions on secondary standards. Given the nature of this new requirement 

and the modeling difficulties that EPA acknowledges, EPA should indicate willingness 

to grant these extensions. 

EPA supports having language in the implementation portion of the preamble 

that identifies where flexibility can be provided on CAA timelines. As noted 

below, we refer to several places where flexibility could be provided, in the 

context of taking preliminary comment on implementation approaches that 

we would more specifically address in the upcoming implementation 

rules/guidance. To further emphasize the point, we could add a general 

statement at the end of the first paragraph of the introduction, to the effect of: 

"This discussion also highlights relevant CAA provisions that provide potential 

flexibility with regard to meeting implementation timelines under the Act." 

Also, with respect to the specific example, we can add a sentence to the 

sections on implementing the primary and secondary standards which 

references the possibility of an area obtaining a 1-year extension to its 
attainment date if the air quality data for the last of the 3 years evaluated to 

determine attainment is below the level of the standard; and the possibility of 

an area obtaining a second 1-year extension to its attainment date if the 

average of the air quality data for the last of the 3 years evaluated to 

determine attainment AND the first extension year is below the level of the 

standard.

Please note that the following sections in the draft preamble already refer to 

certain provisions providing flexibility to states:

- The Designations section states: "Section 107(d)(1)(B)(i) further provides, 

“Upon promulgation or revision of a NAAQS, the Administrator shall 

promulgate the designations of all areas (or portions thereof) ... as 

expeditiously as practicable, but in no case later than 2 years from the date of 

promulgation. Such period may be extended for up to one year in the event the 

Administrator has insufficient information to promulgate the designations.” 

- The Section 110(a)(2) Infrastructure SIP section states: "Section 110(b) of 

the CAA provides that the EPA may extend the deadline for the 

“infrastructure” SIP submission for a new secondary standard by up to 18 

months beyond the initial 3 years. The EPA currently believes it would be 

more efficient for states and the EPA if each affected state submits a single 

section 110 infrastructure SIP that addresses both the revised primary annual 

PM2.5 NAAQS and the new secondary PM2.5 visibility index NAAQS at the 

same time (i.e., within 3 years of promulgation of any revisions to the NAAQS 

for PM), because the EPA does not at present discern any need for there to be 

any substantive difference in the infrastructure SIPs for the two standards. 

However, the EPA also recognizes that states may prefer the flexibility to 

submit the secondary NAAQS attainment SIP at a later date. The EPA solicits 

comment on this timing aspect."

- The section on Implementing the Primary PM2.5 NAAQS states: 

"Under section 172, states are required to submit SIPs within 3 years of the 

effective date of area designations by EPA. These plans need to show how the 

nonattainment area will attain the primary PM2.5 standards “as expeditiously 

as practicable,” but presumptively no later than within 5 years from the 

effective date of designations. However, in certain cases, the EPA can approve 

attainment dates up to 10 years from the effective date of designations, as 

appropriate, considering the severity of the air quality concentrations in the 

area, and the availability and feasibility of emission control measures."

"Under the approach outlined in the implementation rule for the 1997 PM2.5 

NAAQS, for an area that can demonstrate it will attain the standard within the 

presumptive 5-year period from designation, its attainment demonstration 

will be considered to meet the RFP requirement. The EPA believes it is 
appropriate to apply this same approach for the revised annual primary 

PM2.5 standard."

- The section on Implementing the Secondary PM2.5 NAAQS states: 

"For secondary NAAQS, however, section 172(a)(2)(B) defines the attainment 

date for an area designated nonattainment as “the date by which attainment 

can be achieved as expeditiously as practicable” but with no maximum 

limitation. Thus, it is possible for EPA to approve a part D SIP that provides for 

attainment of the secondary standards by a date more than 10 years after the 

date of designation with an appropriate demonstration."

- The sections on Transportation Conformity and General Conformity each 

state that these programs do not apply in a nonattainment area until one year 

after the designations are effective, allowing for an appropriate transition 

between old and new standards.

Questions 25 and 26 are answered collectively below:

25) Under 40 CFR 52.21(o) and (p), visibility analyses are routinely conducted as part 

of the PSD process. Commenters express concern regarding the potential creation 

of a different set of analytical requirements for the PM2.5 visibility index that may 

create "competing" techniques for visibility assessment between the proposed 

PM2.5 visibility index and Class I procedures which could undermine existing 

processes and requirements used to protect visibility in Class I wilderness areas. 

26) Some commenters suggest that the Agency remove the language describing a 

paucity of supporting speciation data. This language could be construed such that 

the current methods used for visibility assessment for Class I analyses are not 

adequate, and that EPA is instead proposing to use a simple surrogacy technique. 

The implications of this could weaken the technical credibility of the tools used for 

Class I visibility assessments under 40 CFR 52.21(p) or the Class II visibility 

assessments under the Additional Impact Analysis ( 40 CFR 52.21(o)) of the PSD 

rule. Moreover, at 70 FR 39121 EPA identified the CALPUFF system as "the best 

currently available tool for analyzing the visibility effects of individual sources." 

These commenters requested clarification upon why the methods that have been 

routinely used for visibility assessment under the PSD program are not deemed 

applicable to the proposed PM2.5 visibility index. 

We agree that the current preamble language the PM2.5 surrogacy approach 

for the proposed secondary visibility standard should be modified to clarify 

the rationale for the policy as well as explain that this surrogacy policy in no 

way impacts the assessments of visibility for PSD purposes under 40 CFR 
52.21(o) and (p), calls into question the technical adequacy of these 

assessments or creates a different and 'competing' set of analytical 

requirements fore the Class I procedures. Please see attached edits intended 

to address these concerns on page 409 through 413 of the preamble. We 

welcome any additional edits for interagency reviewers.