### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

1 I. Responses to Interagency Comments Submitted to EPA on November 19, 2014

(1) Comment For insertion on pg 33 of the preamble:

Wildfires pose a direct threat to public safety

– a threat that can be mitigated through management of wildland vegetation. Besides the physical threat to life and property posed by wildfires, they also affect air quality. Wildfire emissions do significantly contribute to periodic high levels and affects background levels of ozone (Jaffe, D.A. and N.L. Wagner, 2012), especiall y as standards approach background levels (Emery, C. et al., 2012). As has been acknowledged by EPA previously, fires play an important ecological role across the globe . Wildfire benefit s those plant and animal species that depend upon natural fires for pr opagation, habitat restoration, and reproduction , as well as myriad ecosystem functions (e.g., carbon sequestration)

. Attempts to exclude wildland fire have resulted in unintended consequences, including increased risks to both humans and ecosystems. Indee d, “Fire policy that focuses on [wildfire] suppression only, delays inevitable, promising more dangerous and destructive future...fires” (Stephens, S. et al., 2013). Most North American plant communities evolved with recurring fire and are dependent on recu rring fire for maintenance. Fires also reduce fuel load, unnatural understory, and tree density, helping to reduce the risk of catastrophic wildfires. The use of prescribed fire can influence the occurrence of catastrophic wildfires which will have direct impacts on high level impacts to ozone , background levels and subsequent public health effects. Wildfire and prescribed fire are both part of the natural background that will need further consideration during development of implementation rules for this
st andard. EPA has policies that allow for the exclusion of air quality monitoring data from design value calculations when they are substantially affected by certain background influences. However, the CAA requires the EPA to set the NAAQS at levels requisit e to protect public health and welfare without regard to the source of the pollutant

. The EPA is committed to working with Federal land managers, Tribes and the States, between this draft proposal and the final rule, to refine actions that address ozone impacts while protecting and improving vegetation health and resilience to wildfire and climate risks.

EPA Response: The suggested new paragraph is a discussion of implementation

- related policies specific to wildfire and wildland fire, and does not belong within the overall context of this preamble section. The section, titled “E. Ozone A ir Quality” is intended to be a brief overview of ozone in the U.S. (e.g., monitoring, atmospheric chemistry, emissions and other sources, meteorology, past trends, and possible futures). This section does not either logically or appropriately cover imple mentation

- related policy issues other than to describe generally the types of issues that are addressed in the implementation phase rather than standard setting phase. If we were to incorporate the issues from the above paragraph, EPA believes they would be more appropriately addressed in section VII.F covering Background Ozone. We recommend that a revised

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

2 version of the above paragraph could be inserted in section VII.F.2, titled Exceptional Events Exclusions.

EPA recommends that the following revised t ext could be included in section VII.F.2 as the last paragraph, beginning with the sentence that is currently the last sentence:

Additionally, the EPA intends to develop guidance to address implementing the Exceptional Events Rule criteria for wildfires t hat affect ambient O3 concentrations. Wildfire emissions are a component of background ozone (Jaffe, D.A. and N.L. Wigder, 2012) and can significantly contribute to periodic high ozone levels (Emery, C. et al., 2012). Besides their effect on air quality, w ildfires pose a direct threat to public safety

– a threat that can be mitigated through management of wildland vegetation. Attempts to suppress wildfires have resulted in unintended consequences, including increased risks to both humans and ecosystems. Ind eed, “Fire policy that focuses on [wildfire] suppression only, delays inevitable, promising more dangerous and destructive future...fires” (Stephens, S. et al., 2013). The use of prescribed wildland fire can influence the occurrence of catastrophic wildfires which may help manage the contribution of wildfires to background ozone levels and periodic peak ozone events. Additionally prescribed fires can have benefits to those plant and animal species that depend upon natural fires for propagation, habitat restor ation, and reproduction, as well as myriad ecosystem functions (e.g., carbon sequestration). As previously indicated, the CAA and EPA’s implementing regulations allow for the exclusion of air quality monitoring data from design value calculations when they are substantially affected by certain background influences. However, the CAA requires the EPA to set the NAAQS at levels requisite to protect public health and welfare without regard to the source of the pollutant. The EPA is committed to working with Fe deral land managers, Tribes and the States to address the impact of fire

- related emissions on ozone through appropriate implementation policies.

(2) Comment

Table 3, Page 162:

There is a lot of good information here, but there is not enough explanation to help the reader understand it. The title needs some work for clarity. Maybe some of the information goes in footnotes. We recommend stating in the title whether this table

r efers to long term or short term exposure. Can footnotes to be used to provide the source of the concentration response function

– we assume this is Jerrett et al?

EPA Response: We have added clarifying information to footnote 85 describing the
informat ion in Table 3.

(3) Comment

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

3 Page 163:

The HREA also concludes that lower confidence should be placed in the results of the assessment of respiratory mortality risks associated with long

- term O 3 , primarily because that analysis is based on only one study, though that study is well

- designed, and because of the uncertainty in that study about the existence and identification of a potential
threshold in the concentration

- response function (U.S. EPA, 2014a, section 9.6)

. EPA Response: We have added a new footnote (number 88) clarifying that there is uncertainty about the extent to which mortality risk estimates based on the long

- term metric used in the study by Jerrett et al. (2009) (i.e., seasonal average of 1

- hour dai ly maximum concentrations) reflects associations with long

- term average O 3 versus repeated occurrences of elevated short

- term concentrations

(4) Comment

Page 164:

To evaluate the second issue, the HREA conducted national air quality modeling analyses. These analyses estimated the proportion of the U.S. population living in locations where seasonal averages of daily O 3 concentrations are estimated to decrease in response to reductions in NO X emissions, and the proportion living in locations where
such seasonal averages are estimated to increase. Given the close relationship between changes in seasonal averages of daily O 3 concentrations and changes in seasonal mortality and morbidity risk estimates, this analysis informs consideration of the extent to which the risk results in urban study areas represent the U.S. population as a whole. This representativeness analysis indicates that the majority of the U.S. population lives in locations where reducing NO X emissions would be expected to result in decreases in warm season averages of daily maximum 8

- hour ambient O 3 concentrations.

EPA Response: Several parts of the notice discuss EPA’s consideration of this issue, including p. 158 ; bottom of p. 201 to top of p. 202; p. 204; p. 217 ; bottom of p. 179 to p. 183; p. 217 to top p. 218; and p. 312 to 313 (page numbers refer to the track changes version of the notice sent by EPA to OMB on November 21, 2014). The notice also cites to HREA analyses that evaluated this issue.

(5) Comment

Page 167 Commented [A1]: Isn’t another key with the long term studies the potential for double counting?

Commented [A2]: Are there any environmental justice implications associated with the areas where there are NOx sources, and thus ozone levels expected to get highe r?

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

4 To the extent adverse O 3 - attributable effects are more strongly supported for higher ambient concentrations (which are consistently reduced upon air quality adjustment), the impacts on risk estimates of increasing low O 3 concentrations reflect an important source of uncertainty.

EPA Response: The views of the Administrator regarding the relative weight it is appropriate to place on the various exposure and risk metrics are discussed in detail in sections II.D.5 and II.E.4. d.

(6) Comment

Page 172:

In addition to lung function decrements, a A vailable studies have also evaluated either most of these effects (i.e., lung function decrements, respiratory symptoms or , airway inflammation) following exposures to O 3 concentrations below 75 ppb. Table 3

- 1 in the PA highlights the group mean results of individual controlled human exposure studies that have evaluated exposures of healthy adults to O 3 concentrations below 75 ppb (U.S. EPA, 2014c). The studies included in Table 3

- 1 of the PA indicate that some subjects experience a combination of lung function decrements and respiratory symptoms (after the fifth and sixth exercise period) following exposures to O 3 concentrations as low as 72 ppb, 1 and lung function decr ements and airway inflammation following exposures to O 3 concentrations as low as 60 ppb.

The PA also notes consistent results in some panel studies of O 3 - associated lung function decrements. In particular, T t he PA notes that epidemiologic panel studies i n children and
adults consistently indicate O 3 - associated lung function decrements when on

- site monitored concentrations were below 75 ppb, although with the evidence becom es ing less
consistent at lower O 3 concentrations (U.S. EPA, 2014c, section 3.1.4.1).

EPA Response: We have made edits to these paragraphs that are consistent with interagency comments, and that are consistent with our responses to similar comments
submitted to EPA on November 12 and November 18

. (7) Comment

Page 180

1 As noted above, for the 70 ppb exposure concentration Schelegle et al. (2009) reported that the actual 6.6

- hour mean exposure concentration was 72 ppb. Commented [A3]: Again, did EPA look at any EJ implications

– this is a risk

- risk trade off.

Commented [A4]: Consider edits to this paragraph for transparency and clarity.

Commented [A5]: Per prior question about if these are the same people showing both stat sign diff in FEV1 and symptoms.

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

5 iii. Important Uncertainties

The PA also notes that there are important uncertainties associated with analyses of air quality in locations of epidemiologic studies. For example, the PA notes that while multicity studies generally have greater statisti cal power and geographic coverage than single

- city studies, there is often greater uncertainty in conclusions about the extent to which multicity effect estimates reflect associations with air quality meeting the current standard (U.S. EPA, 2014c, section 1.3.1.2.1). This is particularly the case for the multicity studies evaluated in this review with some study locations meeting the current standard and others violating that standard. Specifically for the four Canadian multicity studies discussed above, th e PA notes that interpretation of air quality information is complicated by uncertainties in the extent to which multicity effect estimates can be
attributed to ambient O 3 in the majority of locations, which would have met the current standard, versus O 3 i n the smaller number of locations that would have violated the standard.

EPA Response: A new introductory paragraph has been added to this section to clarify
the consideration of uncertainties in developing the PA conclusions.

(8) Comment

Beginning on page 185:

For exposures of concern at or above 60 ppb, the PA highlights the following key

observations at a standard of 75 ppb:

(1) On average over the years 2006 to 2010, the current standard is estimated to allow approximately 10 to 18% of children in urban study areas to experience one or more exposures of concern at or above 60 ppb. Summing across urban study areas, these percentages correspond to almost 2.5 million children experiencing approximately 4 million exposures of concern a t or above 60 ppb during a single O 3 season. Of these children, almost 250,000 are asthmatics. (2) On average over the years 2006 to 2010, the current standard is estimated to allow approximately 3 to 8% of children in urban study areas to experience two or m ore exposures of concern to O 3 concentrations at or above 60 ppb. Summing across the urban study areas, these percentages correspond to almost 900,000 children (including almost 90,000 asthmatic children) estimated to experience at least two O 3 exposure

co ncentrations at or above 60 ppb during a single O 3 season. Commented [A6]: Some commenters are confused by the placement of this section (after the discussion of the “conclusions” of the PA. Is this section outlining the uncertainties in the conclusions or were these uncertainties taken into account when the conclusions we developed?

Commented [A7]: See parallel requests for adding “at a standard of 75 ppb” throughout pages 195

- 192 (for brevity, not all instances copied here)

Commented [A8]: Please develop a standard footnote that is used whenever EPA refers to the number of children.
T hese numbers assume all child ren respond, extrapolated from the fact that only 10% of the healthy adults in the clinical studies responded gt 10% change in FEV. Given the assumption is that for children that would be adverse, there is margin of safety built in on a variety of le vels, from a) the % responding; b) the severity of the re response. These are influenced by how severe the child’s asthma is and the extent of proper medical management of the child’s asthma. Thus, with increasing health care coverage, these numbers migh t be substantial over estimates.

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

6 (3) In the worst

- case years (i.e., those with the largest exposure estimates), the current standard is estimated to allow approximately 10 to 25% of children to experience one or more exposures of con cern at or above 60 ppb, and approximately 4 to 14% to experience two or more exposures of concern at or above 60 ppb. For exposures of concern at or above 70 ppb, the PA highlights the following key observations at a standard of 75 ppb :

(1) On average over the years 2006 to 2010, the current standard is estimated to allow up to approximately 3% of children in urban study areas to experience one or more exposures of concern at or above 70 ppb. Summing across urban study areas, almost 400,000 children (includi ng almost 40,000 asthmatic children) are estimated to experience O 3 exposure concentrations at or above 70 ppb during a single O 3 season. (2) On average over the years 2006 to 2010, the current standard is estimated to allow less than 1% of children in urban study areas to experience two or more exposures of concern
to O 3 concentrations at or above 70 ppb. (3) In the worst

- case years, the current standard is estimated to allow approximately 1 to 8% of children to experience one or more exposures of concern at or above 70 ppb, and up to approximately 2% to experience two or more exposures of concern, at or above 70 ppb. For exposures of concern at or above 80 ppb, the PA highlights the observation that the current standard is estimated to allow about 1% or fewer c hildren in urban study areas to experience exposures of concern at or above 80 ppb, even in years with the highest exposure estimates.

b. Lung function risk assessment

– key observations

As discussed above (II.C.3.a), the HREA estimates risks of moderate to large lung function decrements (i.e., FEV 1 decrements > 10%, 15%, or 20%) in school

- aged children (ages 5 to 18), asthmatic school

- aged children, and the general adult population for 15 urban study areas. As for exposures of concern, the PA focuses on l ung function risk estimates in children (including children with asthma).

Compared to risks associated with recent air quality, risk estimates for air quality just meeting the current standard are consistently smaller across urban study areas (U.S. EPA, 2 014a, Appendix 6B). When averaged over the years evaluated in the HREA, risk reductions of up to about 40% were estimated compared to recent air quality. These reductions reflect the consistent decreases in relatively high ambient O 3 concentrations upon ad justment to just meet the current standard (U.S. EPA, 2014a, Chapter 4). Such reductions in estimated lung function risks are evident throughout urban study areas, including in urban cores and in surrounding areas (U.S. EPA, 2014, Appendix 9A).

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

7 Based on Fi gures 3

- 11 to 3

- 14 in the PA (U.S. EPA, 2014c), and the associated details described in the HREA (U.S. EPA 2014a, chapter 6), the PA highlights key observations with regard to lung function risks estimated in children for air quality adjusted to just meet the current standard. These key observations are presented below for
FEV 1 decrements > 10, 15, and 20%.

With regard to decrements > 10%, the PA highlights the following key observations at a standard of 75 ppb:

With regard to decrements > 15%, the PA highlights the following key observations at a standard of 75 ppb :
With regard to decrements > 20%, the PA highlights the following key observations at a standard of 75 ppb :
With regard to total mortality or morbidity associated with short

- t erm O 3 , the PA

notes the following at a standard of 75 ppb :

With regard to respiratory mortality associated with long

- term O 3 , the PA notes the following at a standard of 75 ppb :
EPA Response: We have added text to clarify that exposure and risk estimates are for air quality adjusted to just meet the current O 3 standard. We have also added a footnote reiterating the due to variability in responsiveness, only a subset of individuals who experience exposures at or above a benchmark concentration can be expec ted to experience adverse health effects.

(9) Comment

Page 201 (same with footnote 89 on page 203)

Reductions in O 3 precursor emissions (i.e., NO X ) could also increase public health protection by reducing the ambient concentrations of pollutants other than O 3 . For example, in their advice on the second draft HREA CASAC acknowledged the potential for ambient NO 2 concentrations to be affected by changes in NO X emissions (Frey, 2014a, p. 10). Consistent with this, the PA notes that NO X emissions contribute to ambient NO 2 , and NO X and VOCs can contribute to secondary formation of PM 2.5 constituents, including ammonium sulfate (NH 4 SO 4 ), ammonium nitrate (NH 4 NO 3 ), and Commented [A9]: It is not clear why this paragraph is here

– why it is part of the argument about the choice of a standard for ozone vs. in the benefits analysis.

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

8 organic carbon (OC). Therefore, at some times and in some locations, control strategies that would reduce NO X emissions (i.e., to meet an O 3 standard) could reduce ambient concentrations of NO 2 and PM 2.5 , resulting in health benefits beyond those directly associated with reducing ambient O 3 concentrations

. EPA Response: While it is not the basis for the proposed decisions reached by the
Administrator , this is an issue that is acknowledged in the PA and that was discussed by CASAC. The text indicated reflects that acknowledgment in the PA and the discussion of this issue in CASAC’s letter to the Ad ministrator.

(10) Comment

Page 204:

In addition, based on the consistency of findings across studies and evidence for the coherence of results from different scientific disciplines, strong evidence indicates that certain populations are at increased risk of experiencing O 3 - related effects, including the most severe effects. These include populations and lifestages identified in previous reviews (i.e., people with asthma, children, older adults, outdoor workers) and populations identified since the las t review (i.e., people with certain genotypes related to
antioxidant and/or anti

- inflammatory status; people with reduced intake of certain antioxidant nutrients, such as Vitamins C and E).

EPA Response: To avoid confusion with the ISA conclusions, the wo rd “strong” has
been removed.

II. Responses to Additional Interagency Comments Submitted to EPA

(1) This is a f

ollow

- up to EPA’s prior 11

- 14

- 2014 response to General Conformity related issues raised by interagency commenters

. EPA’s understanding of the most recent issues raised by USDA: USDA would like EPA to extend the grace period for general conformity applicable to federal activities in designated nonattainment areas, and address a concern they have about the viability of the “emissions inventory option” for “presumed conformity” in the General Conformity
Rule. On the latter, the concern is that this option is not realistically available to federal agencies prior to states establishing approved emissions inventories for newly designated
nonattainment are as.
EPA Response: Regarding the extension of the grace period, as EPA indicated in an earlier response, the CAA establishes the requirement that conformity applies 1 year after Commented [A10]: Please clarify the difference between “adequate evidence” as stated earl ier in the document (e.g., page 134 states:

Overall, the factors for which the ISA concludes there is adequate evidence of increased risk for experiencing O 3 - related effects were related to asthma, lifestage (children and older adults), genetic variabil ity, dietary factors, and working outdoors.

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

9 an area is designated nonattainment. The CAA does not provide discretion for EPA to revise this requirement to extend the grace period beyond 1 year. Regarding the options for federal actions in nonattainment areas to be deemed to conform, the General Conformity Rule, which EPA last revised in 2010 with considerable input from fed eral agencies (including USDA) provides several methods. A method that was added in the 2010 revision allowing prescribed burns to be considered “presumed to conform” when conducted under approved smoke management plans or by using basic smoke management practices deemed to satisfy the general conformity requirement.

Another method for satisfying these requirements involves comparing the sum of the total emissions from the federal actions plus other emissions in the area to the emissions budget in the appl icable SIP. In cases where the SIP has not been developed yet there is an emissions inventory option. This option allows federal emissions activities to conform if they do not increase the total area’s emissions above the nonattainment
area’s baseline emis sions inventory. The baseline emissions inventory can be the most current calendar year with a complete emissions inventory available before an area is designated. This method was also available prior the 2010 revision to the General Conformity Rule, and continues to be available. Federal agencies should recognize that this emissions inventory option is not available until states have submitted approved area

wide inventories. Since this option relies on states to timely develop these inventories,
EPA en courages potential federal stakeholders to work with states as soon as possible if a nonattainment designation is anticipated to ensure the federal activities they are concerned about are adequately accounted for in state inventories if the federal actors intend to use the emissions inventory method to demonstrate conformity.

There are several other flexible approaches available for federal agencies to comply with their general conformity responsibilities not mentioned in this response. The EPA is availab le to assist federal agencies in using these approaches when federal actions are being planned. The EPA does not at this time have specific plans to review the General Conformity Rule for purposes of exploring additional presumptive conformity methods

as a result of a potential revision to the existing ozone NAAQS, but will consider whether a revised NAAQS creates new challenges not already addressed by the recent 2010 revision to those rules.

(2) Revisions related to the secondary standard made in response to interagency comments (beyond editorial, simple clarifications), beyond that noted in responses sent to OMB on November 13, 2014 :

### Summary of EPA Responses to Interagency Working Comments on Draft Language under EO12866/13563 Interagency Review.

10 a . revision regarding solicitation of comment on retaining current standard and associated
rationale

– section IV.F

b

. clarification for text regarding crop yield loss impacts in Administrator’s conclusions
section

– section IV.D.5

c . Revisions to reduce extraneous discussion wrt crops

– sections IV. B.1.c, IV.D.1.,
IV.E.2

d . Clarification of the framework used for decisio n

- making on the secondary standard

– beginning of section IV