Document ID: EPA-HQ-OAR-2013-0691-0137
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2016-08-24T04:00Z

PM2.5 SIP Requirements Rule (RIN 2060-AQ48)
Changes in Response to Second Set of Interagency Comments as of 7/15/2016
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(Page references are to page numbers in draft final rule)
Response to Comment #1:
EPA would address by making the following change to the Table on Page 21:

Table 1. Total Emissions of PM2.5 and Precursors for Major Sectors in PM2.5 Nonattainment Areas[a] (in tons/year)
           Source: 2011 National Emissions Inventory (Version 2)[b]
Category
                                 Direct PM2.5
                                      SO2
                                      NOx
                                      VOC
                                      NH3
Fuel combustion, electric generating utilities (EGUs)
                                                                         11,339
                                                                        324,658
                                                                         82,509
                                                                          3,001
                                                                          3,572
Fuel combustion, industrial
                                                                         10,286
                                                                         23,762
                                                                         57,690
                                                                          6,251
                                                                            892
Fuel combustion, other
                                                                         29,582
                                                                          8,224
                                                                         60,636
                                                                         32,320
                                                                          8,819
Chemical and allied products 
                                                                          1,504
                                                                          1,329
                                                                          1,056
                                                                          2,828
                                                                            685
Metals processing
                                                                          4,037
                                                                         19,490
                                                                          4,543
                                                                          4,586
                                                                            130
Petroleum and related industries
                                                                          1,534
                                                                          7,273
                                                                          3,775
                                                                         18,830
                                                                            215
Other industrial processes
                                                                         24,168
                                                                          8,466
                                                                         22,599
                                                                         24,928
                                                                          1,094
Solvent utilization
                                                                          1,089
                                                                             39
                                                                             56
                                                                        242,022
                                                                             68
Storage and transport
                                                                          3,420
                                                                            628
                                                                          7,067
                                                                         55,410
                                                                          3,684
Waste disposal and recycling
                                                                          4,143
                                                                            830
                                                                          4,130
                                                                         16,492
                                                                         19,389
Onroad mobile
                                                                         21,073
                                                                          2,598
                                                                        540,800
                                                                        234,136
                                                                         17,525
Offroad mobile
                                                                         13,660
                                                                          5,874
                                                                        239,169
                                                                        152,504
                                                                            150
Miscellaneous (includes  emissions from fire,[c] dust and some agricultural operations)
                                                                        158,565
                                                                          7,368
                                                                         13,734
                                                                        248,835
                                                                        236,577
                                                                          Total
                                                                        284,401
                                                                        410,540
                                                                      1,037,764
                                                                      1,042,144
                                                                        292,800
a There were 33 areas designated as nonattainment for the 1997, 2006, or 2012 PM2.5 NAAQS as of 6/6/2016. These areas were comprised of 67 whole or partial counties. The emissions data in this table represents whole county emissions for the 67 counties because such data is readily available in EPA databases. Actual emissions totals for the 33 nonattainment areas in aggregate would be somewhat lower because some nonattainment areas include partial counties. 
[b] For more details on the definitions of the emission categories listed in Table 1, see Sector/Tier crosswalk table for the 2011 NEI, available at: ftp://ftp.epa.gov/EmisInventory/2011/doc/scc_eis_crosswalk_2011neiv1.xlsx.
[c] Emissions from fire include wildfire, prescribed fire, and agricultural burning.
Response to Comments #2 and 3:
EPA would address this comment by deleting 3 sentences from "proposed rule" section on page 111 and adding them to beginning of "final rule" section (with some minor edits). Fourth sentence and footnote was added per recommendation on interagency call. It is from bottom of page 1 of "Wildland fire and air quality" EPA-DOI-USDA joint statement from April 2016. 

      b. Managing Emissions From Wildfire and Wildland Prescribed Fire. 
      i. Proposed Rule.
      The EPA proposed to recommend as guidance but not as a requirement of the final rule that, if wildfire impacts are significant, contributing to exceedances of the standard, then states should consider RACM for wildfires (which RACM could include a required program of prescribed fires). The EPA also proposed to recommend that states should consider RACM for managing emissions from prescribed fires (including those prescribed fires conducted to reduce future wildfire emissions). The proposal noted that information is available from the DOI and the USDA Forest Service on smoke management programs and basic smoke management practices (BSMP). The EPA requested comment on the concept of, and practical considerations associated with RACM for wildfire and RACM for prescribed fire, including such issues as how such measures can be characterized in the emissions inventory and attainment demonstration and made federally enforceable for adoption in a SIP.
      ii. Final Rule.
      Wildfire can make a large contribution to air pollution (including PM2.5), and wildfire events can threaten public safety. These effects can be mitigated through management of wildland vegetation, including through prescribed fire. Such mitigation can help manage the contribution of fires to PM2.5 levels in nonattainment areas. Prescribed fire (and some wildfires) can mimic the natural processes necessary to maintain fire dependent ecosystems, minimizing catastrophic wildfires and the risks they pose to safety, property and air quality.

Response to Comment 4:
EPA would make the following changes to page 25-26 to assure that the limited inventory discussion that is provided regarding other source categories is similarly provided for fires.  Language referring to fire emissions here is similar to language added to table 1. It is beyond the scope of this notice to provide more extensive inventory or modeling technical discussion specifically for fires.
d. SOA Formation. As discussed earlier, the OM component of ambient PM2.5 is a complex mixture of hundreds or even thousands of anthropogenic and biogenic organic compounds. These compounds are either emitted directly from sources (i.e., as "primary" PM2.5) or formed by reactions in the ambient air to make SOA (i.e., as "secondary" PM2.5).
VOC (both anthropogenic and biogenic) are key precursors to the SOA component of PM2.5. The relative importance of these compounds in the formation of organic particles varies between geographic areas, depending upon local emission sources, atmospheric chemistry and season of the year. It should be further noted that not all inventoried VOC may be contributing to the formation of organic particles. For example, chemical reactions involving VOC are generally accelerated in warmer temperatures, and for this reason studies show that SOA typically comprises a higher percentage of PM2.5 in the summer than in the winter. 
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Sources of VOC include mobile sources, petrochemical manufacturing, oil and gas emissions, fire emissions (including wildfire, prescribed burning, and agricultural burning), and solvents. In addition, some biogenic VOC, emitted by vegetation such as trees, can also contribute significantly to SOA formation, especially in heavily forested areas, such as the southeastern U.S. It should be noted, however, that anthropogenic contributions to SOA are likely highest in the wintertime when biogenic SOA levels are lower; conversely, in the summertime, biogenic contributions to SOA are likely higher. Despite significant progress that has been made in understanding the origins and properties of SOA, it remains the least understood component of PM2.5 and continues to be a significant topic of research and investigation.

Response to Comments 5 and 6:
EPA would make the following change to pages 115-116. As discussed on the 7/14/16 call, it was noted that there already is a statement in the document about future dialogue between agencies and other parties (italicized text). It was agreed that another similar statement is not needed 3 paragraphs later. Instead, the new sentence at the bottom of the page refers to the first statement. 
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      To be clear, nothing about this policy regarding RACM is intended to suggest that fires should be ignited in wildland (or elsewhere) without regard to the air quality or public health consequences. As noted earlier, the EPA believes these consequences are important to address, and intends to engage in dialogue with the FLMs, air agencies, tribes, state and private land owners and other stakeholders at appropriate times, such as during the process for the development of land management plans, about how land managers determine when and where prescribed fire is appropriate for particular wildlands and how to identify and implement appropriate mitigation measures. The policy simply makes clear the EPA's view regarding its recommendation for RACM for wildland fires. 
      The EPA notes that this recommendation regarding RACM differs somewhat from the recommendation that was offered in the preamble as guidance to states as they implement the EPA's recent SIP Requirements Rule for the 1997 and 2008 ozone NAAQS. The reasons for the strategy outlined earlier apply equally well to attainment demonstrations for the ozone NAAQS, and so EPA hereby makes the same recommendation for implementation of these ozone NAAQS as well. This recommendation, offered here in the same manner as the prior recommendation, supersedes the prior recommendation on RACM for wildfire in the preamble to the final SIP Requirements Rule for the 1997 and 2008 ozone NAAQS. The EPA will convey this revised recommendation to the air agencies that are working to prepare these ozone SIPs. The EPA also anticipates making this recommendation as part of our planned rulemaking on implementation of the 2015 ozone NAAQS. Note that this discussion pertains only to the RACM policy, and that other aspects of the fire discussions in the ozone SIP Requirements Rule remain applicable.
      Finally, the EPA notes that, because a significant element of the rationale for this policy is the uncertainty in the timing of wildfires, we may reconsider this recommendation in the future, if adequate tools emerge that allow for predicting fire emissions with sufficient specificity. However, even if such tools emerge, due to inherent uncertainties it may be impossible to satisfactorily incorporate the use of such information into an attainment demonstration framework. 
      iii. Comments and Responses.
      The EPA received many comments expressing agreement with EPA's recognition of the importance of wildland prescribed fire, and welcoming continued dialogue among states, the EPA, and other federal agencies on how best to ensure that land managers have adequate management tools available, including prescribed fire and some wildfire, but also to ensure that use of these tools does not result in unhealthy air. As noted in the previous section, he EPA intends to engage in such dialogue.
      Some commenters also took positions on how specifically to define RACM for wildfires, ranging from required smoke management plans to simply stating that fires themselves are RACM with no further measures required. In light of the fact that EPA did not propose specific guidance on defining RACM for wildfires and typically does not define RACM for specific categories, and the fact that EPA is not recommending that states include RACM as proposed, we are not providing further guidance in response to those comments. Similarly, regarding baseline fire emissions, some commenters provided detailed suggestions regarding approaches to calculating baselines based not on actual fires (which may include periods when fires were suppressed) but on science-based fire regimes, fire return intervals and ecosystem types, including characteristics of wildland vegetation. The EPA notes that this guidance is not establishing or recommending any particular approach to calculating baseline fire emissions.