43246 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
576‘‘Words [in Acts of Congress] importing the 
singular include and apply to several persons.’’ 1 
U.S.C. 1. 577The 2009 and Subsequent MY GHG standards 
for New Motor Vehicles, 73 FR 12156 (March 6, 2008); The On-Board diagnostics system requirements (OBD II) 81 FR 78144 (November 7, 2016), The ZEV program regulations 76 FR 61096 (October 3, 2011), 71 FR 78190 (December 26, 2006)) and the Heavy-duty Truck idling requirements 77 FR 9239 (February 16, 2012). 
57849 FR 18887 (May 3, 1984). 209(b)(1)(B)—the geography and climate 
of California, and the large motor vehicle population in California, which were considered the fundamental causes of the air pollution in California—do not have the same relevance to the question at hand. The atmospheric concentration of GHG in California is not affected by the geography and climate of California. The long duration of these gases in the atmosphere means they are well-mixed throughout the global atmosphere, such that their concentrations over California and the U.S. are substantially the same as the global average. The number of motor vehicles in California, while still a notable percentage of the national total and still a notable source of GHG emissions in the State, is not a significant percentage of the global vehicle fleet and bears no closer relation 
to the levels of GHG in the atmosphere 
over California than any other comparable source or group of sources 
of GHG anywhere in the world. 
Emissions of greenhouse gases from California cars do not generally remain confined within California’s local environment but instead become one part of the global pool of GHG emissions, with this global pool of emissions leading to a relatively homogenous concentration of GHG over the globe. Thus, the emissions of motor vehicles in California do not affect California’s air pollution problem in any way different from emissions from vehicles and other pollution sources all around the world. Similarly, the emissions from California’s cars do not only affect the atmosphere in California but in fact become one part of the global pool of GHG emissions that affect the atmosphere globally and are distributed throughout the world, resulting in basically a uniform global atmospheric concentration. 
EPA then applied the reasoning laid 
out above to the GHG standards at issue in the 2008 waiver denial. Having limited the meaning of this provision to situations where the air pollution problem was local or regional in nature, EPA found that California’s GHG standards did not meet this criterion. 
In the 2008 waiver denial, EPA also 
applied an alternative interpretation where EPA would consider effects of the global air pollution problem in California in comparison to the effects on the rest of the country and again addressed the GHG standards separately from the rest of California’s motor vehicle program. Under this alternative interpretation, EPA considered whether impacts of global climate change in California were sufficiently different 
from impacts on the rest of the country such that California could be considered to need its GHG standards to meet compelling and extraordinary conditions. EPA determined that the waiver should be denied under this alternative interpretation as well. 
(3) Interpretation of Section 209(b)(1)(B) 
Under section 209(b)(1)(B), EPA 
cannot grant a waiver request if EPA 
finds that California ‘‘does not need such State standards to meet compelling 
and extraordinary conditions.’’ The 
statute does not define the phrase ‘‘compelling and extraordinary conditions,’’ and EPA considers the text of section 209(b)(1)(B), and in particular the meaning and scope of this phrase, to be ambiguous. 
First, the provision is ambiguous with 
respect to the scope of EPA’s analysis. 
It is unclear whether EPA is meant to evaluate the particular standard or standards at issue in the waiver request or all of California’s standards in the 
aggregate. Section 209(b)(1)(B) references the need for ‘‘such State standards.’’ Section 209(b)(1)(B) does not specifically employ terms that could only be construed as calling for a standard-by-standard analysis or each individual standard. For example, it does not contain phrases such as ‘‘each State standard’’ or ‘‘the State standard.’’ Nor does the use of the plural term ‘‘standards’’ definitively answer the question of the proper scope of EPA’s analysis, given that the variation in the use of singular and plural form of a word in the same law
576is often 
insignificant and a given waiver request typically encompasses multiple ‘‘standards.’’ Thus, while it is clear that ‘‘such State standards’’ refers at least to all of the standards that are the subject of the particular waiver request before the Administrator, that phrase can reasonably be considered as referring either to the standards in the entire California program, the program for similar vehicles, or the particular standards for which California is requesting a waiver under the pending request. 
There are reasons to doubt that the 
phrase ‘‘such State standards’’ in section 209(b)(1)(B) is intended to refer to all 
standards in California’s program, including all the standards it has historically adopted and obtained waivers for previously. The waiver under 209(b) is a waiver of, and is logically dependent on and presupposes the existence of, the prohibition under 209(a), which forbids (absent a waiver) any state to ‘‘adopt or attempt to enforce any standard [singular] relating to the 
control of emissions from new motor 
vehicles or new motor vehicle engines subject to this part.’’ (Emphasis added.) States are forbidden from adopting a 
standard, singular; California requests 
waivers seriatim by submitting a 
standard or package of standards to 
EPA; follows that EPA considers those submissions as it receives them, 
individually, not in the aggregate with all standards for which it has previously granted waivers. 
Furthermore, reading the phrase 
‘‘such State standards’’ as requiring EPA always and only to consider California’s entire program in the aggregate limits the application of the criterion. Once EPA had determined that California needed its very first set of submitted standards to meet extraordinary and compelling conditions, it is unclear that EPA would ever have the discretion to determine that California did not need 
any subsequent standards for which it sought a successive waiver—unless EPA 
is authorized to consider a later submission separate from its earlier finding. Moreover, up until the ACC program waiver request, California’s waiver request involved individual standards or particular aspects of California’s new motor vehicle program.
577As previously explained, 
however, the ACC waiver program could be considered as the entire new motor vehicle program for California given that it is a single coordinated program comprising a suite of standards that California intended to be a cohesive program for addressing emissions from a wide variety of vehicles, specifically, new passenger cars, light duty trucks, medium passenger vehicles, and certain heavy duty vehicles. 
The application of the phrase ‘‘such 
State standards’’ to state standards in the aggregate may have appeared more reasonable in the context of, for example, the 1984 PM waiver request, as opposed to the present context, as it relates to an application for a waiver with regard to GHG and ZEV standards.
578In the 1984 request, the 
agency confronted the need for a reading of ‘‘such State standards’’ in section 209(b)(1)(B) that would be consistent with the State’s ‘‘in the aggregate, at least as protective’’ finding under the root text of 209(b)(1),’’ 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00262 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243247 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
579The intent of the 1977 amendment was to 
accommodate California’s particular concern with 
NO X, which the State regards as a more serious 
threat to public health and welfare than carbon monoxide. California was eager to establish oxides of nitrogen standards considerably higher than applicable Federal standards, but technological developments posed the possibility that emission control devices could not be constructed to meet both the high California oxides of nitrogen standard and the high Federal carbon monoxide standard. MEMA I, 627 F.2d at 1110 n.32. because Congress explicitly allows 
California to adopt some standards that are less stringent than Federal standards. EPA explained that the phrase ‘‘in the aggregate’’ was specifically aimed at allowing California to adopt less stringent CO standards at the same time when California wanted to adopt NO
Xstandards that were 
tighter than the Federal NO Xstandards, 
to address ozone problems.579California 
reasoned that a relaxed CO standard would facilitate the technological feasibility of the desired more stringent NO
Xstandards. When evaluating that 
waiver request, EPA noted that it would be inconsistent for Congress to allow EPA to look at each air pollutant separately for purposes of determining compelling and extraordinary conditions for that air pollution problem, while at the same time allowing California to adopt standards for a particular air pollutant that was less stringent than the Federal standards for that same pollutant. EPA proposes to determine that the balance of textual, contextual, purposive, and legislative- history evidence at minimum supports the conclusion that it is ambiguous whether the Administrator may consider whether California needs the particular standard or standards under 
review to meet compelling and extraordinary conditions. 
Second, the statute does not speak 
with precision as to the substance of 
EPA’s analysis. ‘‘Compelling and extraordinary conditions,’’ as the history of the 2008 waiver denial and 2009 reconsideration and grant narrated above demonstrates, is a phrase susceptible of multiple interpretations, particularly in the context of GHG emissions and associated, global environmental problems. EPA believes that the term ‘‘extraordinary’’ is most reasonably read to refer to circumstances that are specific to 
California and the term is reasonably interpreted to refer to circumstances that are primarily responsible for causing the air pollution problems that the standards are designed to address, such as thermal inversions resulting from California’s local geography and wind patterns. (Conditions that are similar on a global scale are not ‘‘extraordinary,’’ especially where ‘‘extraordinary’’ conditions are a predicate for a local deviation from national standards.) Support for this interpretation can be found in pertinent legislative history that refers to California’s ‘‘peculiar local conditions’’ and ‘‘unique problems.’’ S. Rep. No. 403, 90th Cong. 1st Sess., at 32 (1967). This legislative history also indicates that California is to demonstrate ‘‘compelling and extraordinary circumstances sufficiently different from 
the nation as a whole to justify 
standards on automobile emissions which may, from time to time, need to be more stringent than national standards.’’ Id. (Emphasis added.) EPA 
believes this is evidence of Congressional intent that separate standards in California are justified only by a showing of particular circumstances in California that are different from circumstances in the nation as a whole to justify separate standards in California. EPA thus, reads the term ‘‘extraordinary’’ in this statutory context as referring primarily to factors that tend to produce higher levels of pollution: Geographical and climatic conditions (like thermal inversions) that in combination with large numbers and high concentrations of automobiles, create serious air pollution problems in California (73 FR 12156, 12159–60). 
Additional relevant legislative history 
supports a decision to examine California’s need for GHG standards ‘‘in the context of global climate change.’’ See, e.g., 73 FR 12161. Specifically, this legislative history demonstrates that Congress did not justify this provision based on the need for California to enact separate standards to address pollution problems of a more national or global nature. Rather relevant legislative history ‘‘indicates that Congress allowed waivers of preemption for California motor vehicle standards based on the particular effects of local conditions in California on the air pollution problems in California.’’ Congress discussed ‘‘the unique problems faced in California as a result of its climate and topography.’’ H.R. Rep. No. 728, 90th Cong. 1st Sess., at 21 (1967). See also Statement of Cong. Holifield (CA), 113 Cong. Rec. 30942–43 (1967). Congress also noted the large effect of local vehicle pollution on such local problems. See, e.g., Statement of 
Cong. Bell (CA) 113 Cong. Rec. 30946. In particular, Congress focused on California’s smog problem, which is especially affected by local conditions and local pollution. See Statement of Cong. Smith (CA) 113 Cong. Rec. 30940–41 (1967); Statement of Cong. Holifield (CA), id., at 30942. See also, 
MEMA I, 627 F.2d at 1109 (noting the 
discussion of California’s ‘‘peculiar local conditions’’ in the legislative history). 
The EPA thus, believes that it is 
appropriate, in evaluating California’s need for a waiver under section 209(b)(1)(B), to examine California’s program as a whole to the extent that the problem is designed to address local or regional air pollution problems, particularly in light of the fact that the State’s aggregate analysis under the root text of 209(1)(b)(1) is designed in part to permit California to adopt standards for 
some criteria pollutants that are less 
stringent than the Federal standards as a trade-off for standards for other criteria pollutants, where the levels of criteria pollutants addressed by California’s standards are caused by conditions specific to California, and contribute primarily to environmental effects that are specific to California. EPA could also review California’s GHG standards themselves even where, as in the instant ACC waiver package, the waiver request is for a single 
coordinated package of requirements 
and amendments that include standards designed to address global environmental effects caused by a globally distributed a globally distributed pollutant, such as GHGs as well as requirements for a compliance mechanism that could likely address both criteria pollutants and GHG emissions, which in this instance are the ZEV requirements. The EPA further notes that in keeping with its pre-2008 interpretation, its review of California’s 
ACC program request under section 209(b)(1)(B) was cursory and undisputed, given that view that the fundamental factors leading to California’s air pollution problems— geography, local climate conditions (like thermal inversions), significance of the motor vehicle population—had not changed over time and over different local and regional air pollutants. Additionally, as previously explained, up until the ACC program waiver, California had relied on the ZEV requirements as a compliance mechanism for criteria pollutants as compared to the ACC program, where CARB for the first time relied on it for GHG emissions reductions. Here, as previously explained, CARB specifically noted that that there was no criteria emissions benefit for its ZEV standards in terms of vehicle emissions because its LEV III criteria pollutant fleet standard was responsible for those emission 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00263 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243248 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
580CARB ACC waiver request at EPA–HQ–OAR– 
2012–0562–0004. reductions.580The EPA therefore, 
believes a review of the grant of the ACC 
program waiver and the agency reasoning underpinning the grant are appropriate at this time. As previously explained, an agency ‘‘must consider . . . the wisdom of its policy on a continuing basis.’’ Chevron, 467 U.S. at 
863–64. This is true when, as is the case here, review is undertaken ‘‘in response to . . . a change in administration.’’ Brand X Internet Services, 545 U.S. at 981. In sum, EPA proposed to conclude that the pre-2008 interpretation of section 209(b)(1)(B) would allow for review of California’s GHG standards in themselves, given that the ACC program is a single coordinated motor vehicle emission control program that is designed to address both traditional, local environmental causes and effects 
(including via criteria pollutants) and 
global air pollution problems. Thus, EPA is proposing that at this time its 
review has led it to propose to 
determine that California does not need its own GHG and ZEV standards, to the extent California intended the ZEV requirements to serve as a compliance option for GHG standards, because GHG emissions do not present conditions specific to California—in the terms of the legislative history discussed above, GHG emissions do not present ‘‘unique problems’’ in California as compared to the whole country. As shown below, GHG emissions could be associated with potential adverse effects in California, but EPA does not believe that these would be sufficiently different from potential adverse effects in either coastal States like Florida, Massachusetts, and Louisiana or the nation as a whole, to constitute a ‘‘need’’ for separate state standards under section 209(b)(1)(B). EPA is of the view, therefore, that GHG emissions would not be associated with ‘‘peculiar local conditions’’ in California that Congress alluded to in promulgating section 209(b)(1)(B). In the alternative, EPA is proposing to determine that California does not need the ACC program GHG and ZEV standards to address compelling and extraordinary conditions, because they will not 
meaningfully address global air pollution problems like the kinds associated with GHG emissions and would not have any meaningful impact on potential adverse effects related to global climate change in California. As shown below, based on this reading of section 209(b)(1)(B), the agency is proposing to find that GHG emissions impacts cannot be considered ‘‘compelling and extraordinary 
conditions’’ such that California ‘‘need[s]’’ separate GHG and ZEV standards for new motor vehicles for MY 2021 through MY 2025. 
(4) Proposed Determination That 
California Does Not Need Its ACC Program Regulations To Meet Compelling and Extraordinary Conditions 
EPA is proposing to withdraw the 
waiver of preemption of the GHG and ZEV standards on two alternative grounds: (1) California ‘‘does not need’’ the standards ‘‘to meet compelling and extraordinary conditions,’’ under section 209(b)(1)(B); (2) even if California does have compelling and extraordinary conditions in the context of global climate change, California does not ‘‘need’’ these standards under section 209(b)(1)(B) because they will not meaningfully address global air pollution problems of the sort associated with GHG emissions. EPA is interpreting section 209(b)(1)(B) to permit the Agency to specifically review California’s need for GHG standards— i.e., standards for a globally distributed 
air pollutant which is of concern for its connection to global environmental effects—as opposed to reviewing California’s need for its motor vehicle program as a whole (including both its GHG-targeting and non-GHG-targeting components), in part because the rest of California’s ACC program consists of standards that are designed to address local or regional air pollution problems. Accordingly, EPA is proposing to find that GHG emitted by California motor vehicles become part of the global pool of GHG emissions that affect concentrations of GHGs on a uniform basis throughout the world. The local climate and topography in California have no significant impact on the long- term atmospheric concentrations of greenhouse gases in California. More importantly, California’s standards for GHG emissions (both the GHG and ZEV standards) would not materially affect global concentrations of GHG levels. Accordingly, even if EPA were to assume California had compelling and 
extraordinary conditions that were uniquely impacted by high levels of 
GHGs, California’s GHG and ZEV 
standards would not meaningfully 
address those concerns and conditions. 
In the alternative, EPA believes that 
even if California has compelling and extraordinary conditions, California 
does not need these standards under 
section 209(b)(1)(B) because they will 
not meaningfully address global air 
pollution problems like the kinds 
associated with GHG emissions. EPA believes that the number of motor 
vehicles in California bears no significant relationship to the levels of GHGs in California. This is because GHGs emissions from cars located in California are relatively small part of the global pool of GHG emissions. Thus, GHG emissions of motor vehicles in California do not affect California’s conditions related to global climate change in any way different from emissions from vehicles and other pollution sources all around the world. Similarly, the GHG emissions from cars in California become one part of the global pool of GHG emissions that affect the atmosphere globally and are distributed throughout the world, resulting in basically a uniform global atmospheric concentration. This is in contrast to the kinds of motor vehicle emissions normally associated with ozone levels, such as VOCs and NO
X, 
and the local climate and topography that in the past have led to the conclusion that California has the need for state standards to meet compelling and extraordinary conditions. Therefore, California does not need its GHG and ZEV standards to ‘‘meet’’ the conditions: a problem does not cause you to ‘‘need’’ something that would not meaningfully address the problem. 
In justifying the need for its GHG 
standards, CARB extensively described climatic conditions in California. ‘‘Record-setting fires, deadly heat waves, destructive storm surges, loss of winter snowpack—California has experienced all of these in the past decade and will experience more in the coming decades. California’s climate— much of what makes the state so unique and prosperous—is already changing, and those changes will only accelerate and intensify in the future. Extreme weather will be increasingly common as a result of climate change. In California, extreme events such as floods, heat waves, droughts and severe storms will 
increase in frequency and intensity. 
Many of these extreme events have the 
potential to dramatically affect human 
health and well-being, critical 
infrastructure and natural systems’’ (78 FR 2129). CARB also provided a 
summary report on the third assessment 
from the California Climate Change 
Center (2012), which described dramatic sea level rises and increases in temperatures (78 FR 2129). These are similar, if not identical to, the justifications that EPA addressed and rejected in the 2008 GHG waiver denial. Notably, in the 2008 denial EPA observed that some of these events— increased temperatures, heat waves, sea level rises, wildfires—were also 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00264 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243249 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
581IPCC. 2015. Intergovernmental Panel on 
Climate Change (IPCC) Observed Climate Change 
Impacts Database, available at http://sedac.ipcc- data.org/ddc/observed_ ar5/index.html. 
582They are also similar to previous claims 
marshalled by Massachusetts over a decade ago. Massachusetts v. EPA, 549 U.S. 497, 522–24 (2007). 
According to Massachusetts, at the time, global sea levels rose between 10 and 20 centimeters over the 20th century as a result of global warming and had begun to swallow its coastal areas. 
58374 FR 66496, 66517–19, 66533 (December 15, 
2009). 584Available in the docket for the January 2013 
waiver decision, Docket No. EPA–HQ–OAR–2012– 0562. occurring across the U.S. (73 FR 12163, 
12165–68). CARB further noted that the South Coast and San Joaquin Valley Air Basins continue to experience some of the worst air quality in the nation and continue to be in non-attainment with the PM and ozone national ambient air quality standards (78 FR 2128–9). The EPA has typically considered nonattainment air quality in California as falling within the purview of ‘‘compelling and extraordinary conditions.’’ California however, did not indicate how the GHG standards would help California in the attainment efforts for these areas. Moreover, as previously noted, the ACC ZEV requirements are intended in part as a GHG compliance mechanism for MYs 2018 through 2025. 
EPA believes that any effects of global 
climate change would apply to the nation, indeed the world, in ways similar to the conditions noted in California.
581For instance, California’s 
claims that it is uniquely susceptible to certain risks because it is a coastal State does not differentiate California from other coastal States such as Massachusetts, Florida, and Louisiana.
582Any effects of global 
climate change (e.g. water supply issues, 
increases in wildfires, effects on agriculture) could certainly affect California. But those effects would also affect other parts of the United States. Many parts of the United States, especially western States, may have issues related to drinking water ( e.g., 
increased salinity) and wildfires, and effects on agriculture; these occurrences are by no means limited to California. These are issues of national, indeed international, concern. Further, these are some of the effects that EPA considered as bases for the section 202(a) GHG endangerment finding, which was a prerequisite for the Federal GHG standards for motor vehicles.
583 
EPA has also previously opined that 
evaluation of whether California’s standards are necessary to meet compelling and extraordinary conditions is not contingent on or directly related to EPA’s cause or contribution finding for the section 202(a) GHG endangerment finding, which was a completely different determination than whether California 
needs its mobile source pollution program to meet compelling and extraordinary conditions in California (79 FR 46256, 46262: August 7, 2014). 
See also Utility Air Regulatory Group 
v. EPA, 134 S. Ct. 2427 (2014) (partially 
reversing the GHG ‘‘Tailoring’’ Rule on grounds that the section 202(a) endangerment finding for GHG emissions from motor vehicles did not compel regulation of all sources of GHG emissions under the Prevention of 
Significant Deterioration and Title V permit programs). 
As also previously indicated, 
California is to demonstrate ‘‘compelling and extraordinary circumstances sufficiently different from 
the nation as a whole to justify 
standards on automobile emissions which may, from time to time, need to be more stringent than national standards.’’ S. Rep. No. 403, 90th Cong. 1st Sess., at 32 (1967). (Emphasis added.) EPA does not believe that these conditions, mentioned above, merit separate GHG standards in California. Rather, these effects, as previously explained, are widely shared and do not present ‘‘unique problems’’ with respect to the nature or degree of the effect California would experience. In sum, EPA finds that any effects of global climate change in California are not ‘‘extraordinary’’ as compared to the rest of the country. EPA is thus, proposing to find that CARB has not demonstrated that these negative impacts it attributes to global climate change are ‘‘extraordinary’’ to merit separate GHG and ZEV standards. 
The ACC program waiver contained 
references to the potential GHG benefits or attributes of CARB’s GHG and ZEV standards program (78 FR 2114, 2130– 2131). CARB repeatedly touted the benefits of both the ZEV and GHG standards as it related to the GHG emissions reductions in California. In one instance, CARB stated that the ACC program regulations for the 2017 through 2025 MYs were designed to respond to California’s identified goals of reducing GHG emissions to 80% below 1990 levels by 2050 and in the near term to reduce GHG levels to 1990 levels by 2020 (78 FR 2114, 2130–31). CARB’s Resolution 12–11, (January 26, 2012).
584In another instance, CARB 
noted that the ZEV regulation amendments were intended to focus primarily on zero emission drive—that is BEVs, FCVs, and PHEVs in order to move advanced, low GHG vehicles from demonstration phase to 
commercialization (78 FR 2130). CARB further noted that ‘‘ZEVs have ultra-low GHG emission levels that are far lower than non-ZEV technology’’ (78 FR 2139). In yet another instance, CARB relied on conclusions from the September 2010 Joint Technical Assessment Report (TAR), which was developed by EPA, NHTSA, and CARB, on effects of the ZEV requirements on GHG standards. This report concluded that ‘‘electric drive vehicles including hybrid(s) . . . battery electric vehicles . . . plug-in hybrid(s) . . . and hydrogen fuel cell vehicles . . . can dramatically reduce petroleum consumption and GHG emissions compared to conventional technologies. The future rate of penetration of these technologies into the vehicle fleet is not 
only related to future GHG and corporate average fuel economy (CAFE) standards, but also to future reductions in HEV/PHEV/EV battery costs, [and] the overall performance and consumer demand for the advanced technologies’’ (78 FR 2142). But nowhere does CARB either show or purport to show a causal connection between its GHG standards and reducing any adverse effects of climate change in California. EPA does 
not believe that identifying methods for reducing GHG emissions and then noting the potential dangers of climate change are sufficient to demonstrate that California needs its standards to meet 
compelling and extraordinary circumstances as contemplated under section 209(b)(1)(B). California also does not need the ZEV requirements to meet ‘‘compelling and extraordinary’’ conditions in California given that the FCV ‘‘travel provision’’ allow manufacturers to generate credits in section 177 states as a means to satisfy those manufacturers’ obligations to comply with the mandate that a certain percentage of their vehicles sold in California be ZEV (or be credited as such from sales in section 177 States). In sum, California did not quantify and demonstrate climate benefits in California that may result from the GHG standards. EPA therefore, proposes to find that it is not appropriate to waive preemption for California to enforce its GHGs standards. EPA continues to believe that any problems related to atmospheric concentrations of GHG are global in nature and any reductions achieved as a result of California’s separate GHG standards will not accrue meaningful benefits to California. Thus, GHG emissions raise issues that do not bear the same causal link between local emissions and local benefits to health and welfare in California as do local or 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00265 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243250 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
585Section 202(a) provides that an emission 
standard shall take effect after such period of time 
as the Administrator finds necessary to permit development and application of the requisite technology, giving appropriate consideration to compliance costs. 
586Although this section generally discusses the 
technological feasibility of CARB’s GHG standards for MY 2021–2025, we believe the current Federal standards are sufficiently similar to (if not less stringent than) the current California standards to serve as an appropriate proxy for considering the technological feasibility of the current California standards. Compare Cal. Code Regs. Tit. 13, 
§ 1961.3 with 40 CFR 89.1818–12. 
587Docket ID No. EPA–HQ–OAR–2012–0562. regional air pollution problems (such as 
criteria pollutants). EPA further finds that atmospheric concentrations of GHGs are not the kind of local or regional air pollution problem Congress intended to identify in the second criterion of section 209(b)(1)(B). These findings also apply to the ZEV provisions given that CARB, in a change from prior practice, and as previously explained, cited its ZEV standards as a means to reduce GHG emissions instead of criteria pollutants for MY 2021 through MY 2025. Thus, EPA is proposing to withdraw the waiver of preemption for the GHG and ZEV 
requirements for MYs 2021 through 2025 because California does not need these provisions to meet compelling and extraordinary conditions. 
(b) Proposed Finding Under Section 
209(b)(1)(C): California’s Standards Are Not Consistent With Section 202(a) 
(1) Introduction 
Under section 209(b)(1)(C), EPA 
cannot grant a waiver request if EPA 
finds that California’s ‘‘standards and accompanying enforcement procedures are not consistent with section 202(a) of the Act.’’
585The EPA is also proposing 
to find that both ZEV and GHG standards for new MY 2021 through 2025 are not consistent with Section 202(a) of the Clean Air Act, as contemplated by section 209(b)(1)(C). Specifically, EPA is proposing to determine that there is inadequate lead time to permit the development of technology necessary to meet those requirements, giving appropriate consideration to cost of compliance within the lead time provided in the 2013 waiver. This finding reflects the assessments in today’s proposal on the technological feasibility of the Federal GHG standards for MY 2021 through 2025.
586 
As previously explained, the MY 2021 
through 2025 Federal and CARB GHG standards were the results of collaboration between CARB and EPA. The respective standards are equally stringent and have the same lead time. (78 FR 2135) CARB’s GHG standards also rely on emerging technology that 
are similar to the ones for the Federal GHG standards, including ZEV-type technologies (78 FR 2136–7). Most importantly, CARB’s feasibility finding, and EPA’s decision to grant the waiver, noted a ‘‘deemed to comply’’ provision that allowed manufacturers of advanced technology vehicles to comply with CARB GHG standards through compliance with the Federal GHG standards as well as utilize the EPA accounting provisions for these vehicles (78 FR 2136). Revisions to the Federal GHG standards, in light of the technology development and availability assessment for those standards, would therefore, implicate the technological feasibility findings that served as the underpinning for EPA’s grant of CARB’s GHG standards waiver. 
Further, because EPA believes that the 
ZEV and GHG standards are intertwined as shown in some of the program complexities discussed above, EPA believes that this provides further justification for withdrawing the waiver of preemption for both standards, under section 209(b)(1)(C). For example, in the waiver request CARB stated that the ‘‘ZEV regulation must be considered in conjunction with the proposed LEV III amendments. Vehicles produced as a result of the ZEV regulation are part of a manufacturer’s light-duty fleet and are therefore included when calculating fleet averages for compliance with the LEV III GHG amendments.’’ CARB’s Initial Statement of Reasons at 62–63, which is in the docket for the waiver decision.
587CARB also noted ‘‘[b]ecause 
the ZEVs have ultra-low GHG emission levels that are far lower than non-ZEV technology, they are a critical component of automakers’ LEV III GHG standard compliance strategies.’’ Id. 
CARB further explained that ‘‘the ultra- low GHG ZEV technology is a major component of compliance with the LEV III GHG fleet standards for the overall light duty fleet.’’ Id. 
Similarly, with regard to CARB’s ZEV 
standards, EPA is now cognizant that certain ZEV sales requirements mandated by CARB are technologically infeasible within the provided lead-time for purposes of CAA 209(b)(1)(C). Specifically, today’s proposal also raises questions as to CARB’s technological projections for ZEV-type technologies, which are a compliance option for both 
the ZEV mandate and GHG standards. CARB’s ZEV regulations also include the travel provision, which allowed manufacturers of ZEVs sold in California to count toward compliance in section 177 States, but which was 
limited to FCVs starting with MY 2018. The manufacturer credit system was premised on ever increasing numbers of ZEVs that would be sold in each of the section 177 States. Challenges for ZEVs in these States include lack of market penetration, consumer demand levels that are lower than projections at the time of the grant of the ACC waiver in 2013, and lack of or slow development of necessary infrastructure. This in turn means that manufacturers in section 177 States are unlikely to meet CARB’s projections that their sales in those States will generate the necessary credits as CARB projected to support the ZEV sales requirement mandate in the lead time provided. 
Today’s proposal indicates challenges 
for the adoption of all ZEV technologies such as lack of required infrastructure and a lower level of consumer demand for FCVs in both California and individual section 177 States, and EPA believes it is now unlikely that manufacturers will be able to generate requisite credits in section 177 States in the lead time provided. In short, EPA is now of the view that CARB’s projections and assumptions that underlay its ACC program and its 2013 waiver application were overly ambitious and likely will not be realized within the provided lead time. Thus, EPA is also proposing to find that CARB’s ZEV standards for MY 2021 through 2025 are not technologically feasible and therefore, are not consistent with section 209(b)(1)(C). 
(2) Historical Waiver Practices Under 
Section 209(b)(1)(C) 
In prior waivers of Federal 
preemption, under section 209(b), EPA has explained that California’s standards are not consistent with section 202(a) if there is inadequate lead time to permit the development of 
technology necessary to meet those requirements, given appropriate consideration to the cost of compliance within that time. California’s accompanying enforcement procedures would also be inconsistent with section 202(a) if the Federal and California test procedures were inconsistent. 
EPA also relies on two key decisions 
handed down by the U.S. Court of Appeals for the D.C. Circuit for guidance regarding the lead time requirements of section 202(a): Natural 
Resources Defense Council v. EPA 
(NRDC), 655 F.2d 318 (D.C. Cir. 1981) (upholding EPA’s lead time projections for emerging technologies as reasonable), and International Harvester 
v. Ruckelshaus (International 
Harvester), 478 F.2d 615 (D.C. Cir. 1979) 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00266 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243251 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
58874 FR 32744, 32774 (July 8, 2009); 47 FR 7306, 
7309 (February 18, 1982); 46 FR 26371, 26373 (May 
12, 1981), 43 FR 25735 (June 14, 1978). (reversing EPA’s refusal to extend 
compliance deadline where technology was presently available on grounds that hardship would likely result if it were a wrongful denial of compliance deadline extension.). EPA further notes the court’s conclusion in NRDC. 
Given this time frame [a 1980 decision on 
1985 model year standards], we feel that there is substantial room for deference to the EPA’s expertise in projecting the likely course of development. The essential question in this case is the pace of that development, and absent a revolution in the study of industry, defense of such a projection can never possess the inescapable logic of a mathematical deduction. We think that the EPA will have demonstrated the reasonableness of its basis for projection if it answers any theoretical objections to the [projected control technology], identifies the major steps necessary in refinement of the technology, and offers plausible reasons for believing that each of those steps can be completed in the time available. 
NRDC, 655 F.2d at 331 (emphasis 
added). 
With regard to appropriate lead time 
in the section 209(b) waiver context, EPA considers whether adequate control technology is presently available or already in existence and in use at the time CARB adopts standards for which it seeks a waiver. If adequate control technology is not presently available, EPA determines whether CARB has provided adequate lead time for the development and application of necessary technology prior to the effective date of applicable standards. As explained above, considerations 
under this criterion include adequacy of lead time, technological feasibility and costs as well as test procedures consistency. Notably, there are similar considerations for Federal standards setting under section 202(a). For example, in adopting the MY 2017 through 2025 GHG standards, section 202(a) required and EPA found in October 2012 that the MY 2017 through 2025 GHG standards are feasible in the lead time provided and that technology costs were reasonable (77 FR 62671–73; October 15, 2012). Even where technology is available, EPA can consider hardships that could result to manufacturers from either a short lead time or not granting a compliance extension. International Harvester, 478 
F.2d at 626. 
Where CARB relies on emerging 
technology (i.e., where technology is 
unavailable at time of grant of waiver), EPA will review CARB’s prediction of future technological developments and determine whether CARB has provided reasoned explanations for the time period selected. Any projections by CARB would have to be subject to ‘‘restraints of reasonableness and does 
not open the door to crystal ball inquiry.’’ NRDC v. EPA, 655 F.2d at 329. 
‘‘The Clean Air Act requires the EPA to look to the future in setting standards, but the agency must also provide a reasoned explanation of its basis for believing that its projection is reliable.’’ Id. 
EPA will make a consistency finding 
where CARB provides for longer lead time in instances in of emerging or unavailable technology at the time 
CARB adopts its standards. In sum, EPA’s review of CARB’s technological feasibility involves both evaluations of predictions for future technological advances and presently available technology. EPA also believes that a longer lead time would allow CARB ‘‘modify its standards if the actual future course of technology diverges from expectation.’’ Id. 
As previously mentioned above, costs 
considerations are also tied to the compliance timing for a particular standard and are thus, relevant for purposes of the consistency determination called for by the third waiver criterion under section 209(b)(1)(C). In evaluating compliance costs for CARB standards, EPA considers the actual cost of compliance in the time provided by applicable California regulations. Compliance costs ‘‘relates to the timing of standards and procedures.’’ MEMA I, 627 F.2d at 1118 
(emphasis in original). Where technology is not presently available, EPA also considers the period necessary to permit development and application of the requisite technology. 
In terms of waiver practice, EPA has 
previously taken the position that technology control costs must be excessive for EPA to find that California’s standards are inconsistent with section 202(a).
588(See MEMA I, 
627 F.2d at 1118 ‘‘Congress wanted to avoid undue economic disruption in the automotive manufacturing industry and also sought to avoid doubling or tripling of the cost of motor vehicles to purchasers.’’) Consistent with this practice, in the ACC program waiver, EPA contended that control costs for the ZEV standards were ‘‘not excessive.’’ ‘‘Under EPA’s traditional analysis of cost in the waiver context, because [an incremental cost of $12,900 in MY 2020] does not represent a ‘doubling or tripling’ of the vehicle cost, such cost is not excessive nor does it represent an infeasible standard’’ (78 FR 2142). EPA now believes that its prior view that a doubling or tripling of vehicle cost 
constitutes an excessive cost or represents an infeasible standard was incorrect. Such a bright line (and extreme) test is inappropriate. Instead, the agency should holistically consider whether technology control costs are infeasible by considering the availability of the technology, the reasonableness of costs associated with adopting it within the required lead time, and consumer acceptance. 
(3) Interpretation of Section 209(b)(1)(C) 
EPA cannot grant a waiver, under 
section 209(b)(1)(C), if California’s 
‘‘standards and accompanying enforcement procedures are not consistent with section [202(a)].’’ Relevant legislative history from the 1967 CAA amendments indicates that EPA is to grant a waiver unless it finds that there is ‘‘inadequate time to permit the development of the necessary technology given the cost of compliance within that time period.’’ This is similar to language found in section 202(a), which is discussed below. Additional relevant legislative history indicates that EPA is not to grant a waiver where ‘‘California standards are not consistent with the intent of section 202(a) of the Act, including economic practicability and technological feasibility.’’ The cross-reference to section 202(a) is an indication of the role EPA plays in 
reviewing California’s waiver request under section 209(b)(1)(C). 
With regard to section 202(a), 
standards promulgated under section 202(a)(1) ‘‘shall take effect after such period as the Administrator finds necessary to permit the development and application of the requisite technology, giving appropriate consideration to the cost of compliance within such period.’’ Section 202(a). Pertinent legislative history from the 1970 and 1977 amendments indicate that EPA ‘‘was expected to press for the development and application of improved technology rather than be limited by that which exists today.’’ S. Rep. No. 1196, 91st Cong., 2d Sess. 24 (1970); H.R. Rep. No. 294, 95th Cong., 1st Sess. 273 (1977). In sum, EPA believes that section 202(a) allows for a projection of lead time as to future technological developments. 
(4) Proposed Finding That California’s 
Standards Are Not Consistent With Section 202(a) 
As previously mentioned, today’s 
proposal now cast significant doubts on EPA’s predictions for future and timely availability of emerging technologies for compliance with Federal GHG standards for MY 2021–2025. It highlights in 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00267 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243252 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
589On May 7, 2018, California issued a notice 
seeking comments on ‘‘potential alternatives to a 
potential clarification’’ of this provision for MY vehicles that would be affected by revisions to the Federal GHG standards. The notice is available at: https://www.arb.ca.gov/msprog/levprog/leviii/ leviii_ dtc_notice05072018.pdf. EPA proposes to 
determine that the ‘‘deemed to comply’’ provision in California’s program does not prevent EPA from finding that California’s ZEV and GHG standards are inconsistent with section 202(a), for two reasons. First, the ‘‘deemed to comply’’ provision is in flux; the state process that may ‘‘clarify[]’’ it renders it unclear whether California will continue to deem a program that may be revised as proposed in this joint rulemaking to comply with its own program. Second, EPA proposes to determine that a ‘‘deemed to comply’’ provision is logically incompatible with a preemption waiver analysis. The entire premise of 209(a) preemption and 209(b)(1) waivers is that California’s standards will differ from the Federal standards. If ‘‘deemed to 
comply’’ provisions in California’s program prevented EPA from determining that California’s standards is inconsistent with section 202(a), then those provisions’ presence would prevent EPA’s analysis under this prong (209(b)(1)(C) from denying it a waiver no matter the content of those standards. 
590CARB waiver request at 27–28, which can be 
found in Docket ID No. EPA–HQ–OAR–2012–0562. 
591Id. The ‘‘hardships’’ referred to are hardships 
that would be created for manufacturers able to comply with the more stringent standards being relaxed late in the process. 
592For example, CARB has made multiple 
revisions to its on-Board diagnostics (OBD) (81 FR 78144 (November 7, 2016)) and the ZEV program regulations (76 FR 61096 (October 3, 2011)). particular challenges for ZEV-type 
technologies, such as BEVs and PHEVs, that California relied on as compliance options for the ZEV mandate requirements and GHG standards. As also previously mentioned CARB’s GHG standards were developed jointly by EPA and CARB with the result that CARB’s GHG standards share a similar structure with EPA GHG standards in terms of both lead time and stringency. For instance, the methodology and underlying data used by CARB to assess technologies and costs were similar to and, in many instances, the same as those used by EPA to assess the Federal 
GHG standards (78 FR 2136). Also, the technological feasibility analyses underlying CARB’s standards were based on several emerging technologies similar to control technologies 
considered by EPA and NHTSA in 
evaluating Federal GHG standards for 
MYs 2021–2025. Id. Additionally, 
CARB’s feasibility finding was premised on a finding of reduced compliance costs and flexibility because of the deemed to comply provisions, which allowed for compliance with Federal GHG standards in lieu of California’s standards.
589In sum, EPA’s findings of 
technological feasibility for the GHG and ZEV standards were premised on the availability of both current and emerging technologies in the lead-time CARB provided for new MY 2021–2025 motor vehicles (78 FR 2138–2139, 2143). These kinds of control technologies would include ZEV-type technologies, which are used as a compliance option for CARB’s GHG standards because their GHG emissions levels are significantly lower than non- ZEV technology. As the NPRM discusses, certain control technology would likely not be fully developed in time for deployment in MY 2021 through 2025 motor vehicles. 
With regard to the ZEV standards, 
CARB’s waiver request contained projections and explanations for ZEVs that included projected sales of FCVs in both California and section 177 States. Specifically, CARB’s projections, at the time, were that nearly every vehicle manufacturer would be introducing BEVs and PHEVs within the next one to three years, and five manufacturers would be commercially introducing FCVs by 2015.
590As explained above, 
the ZEV regulations contains the travel provision that allow manufacturers to comply with the ZEV sales mandate by generating credits for vehicle sales in section 177 States and vice versa. At the grant of the ACC program waiver, EPA found CARB’s assumptions and projections appeared reasonable within the provided lead time for MYs 2021 through 2025 (78 FR 2141–42). 
Technological challenges may serve 
as basis for either a future compliance deadline extension or modifications to the federal GHG standards that would be consistent with today’s proposal and would then raise questions as to CARB’s predictions and projections of technological feasibility and costs. At this time, however, CARB has shown no indication that it intends to either extend the compliance deadline for or modify its standards by providing additional compliance flexibilities. EPA believes it is reasonable, therefore, to consider any expected hardship that would be posed to manufacturers if EPA does not withdraw CARB’s waiver. NRDC, 655 F.2d at 330. An early 
withdrawal of the waiver would also provide a measure of certainty to all manufacturers. ‘‘ ‘[T]the base hour for commencement of production is relatively distant, and until that time the probable effect of a relaxation of the standard would be to mitigate the consequences of any strictness in the final rule, not to create new hardships.’’
591Further, from past 
experience with waivers for challenging standards, EPA is aware that CARB has subsequently either modified compliance deadlines or provided additional compliance flexibilities for such standards.
592EPA also notes that even at the time of the waiver request, 
CARB was already cognizant of challenges presented by both ZEV and GHG standards. CARB noted that although several individual technologies offered substantial CO
2 
reduction potential many of the technologies had only limited deployment in new vehicle models (78 FR 2136). CARB also extended the travel provisions beyond 2017 for FCVs due to insufficient refueling infrastructure in section 177 States as compared to other kinds of ZEV technologies (78 FR 2120; CARB Resolution 12–11 at 15). EPA is, therefore, acting in anticipation of the challenges presented by its GHG and ZEV standards. As previously explained, a late modification or extension of time carries attendant hardships for technologically advanced manufacturers who might have made major investment commitments (International Harvester, 478 F.2d 615). 
EPA believes that today’s proposal, when finalized, would be sufficiently ahead of the compliance deadline for MY 2021 through 2025 and thus, manufacturers would not incur any hardships. Indeed, the expectation is that the proposed withdrawal would provide notice to manufacturers of the intended compliance deadline modifications for MYs 2021 through 2025. 
Finally, the agency is acting on the 
likelihood of increased compliance costs as shown in today’s proposal. (These are costs that will likely be passed on to consumers in most instances.). As previously explained, 
because compliance technologies that California relied on for both ZEV and GHG standards are similar to the technologies considered by EPA in evaluating the feasibility of standards for MYs 2021 through 2025, economies of scale were expected to drive down both manufacturing and technology costs. The EPA, however, now expects that manufacturers may no longer be willing to commit to investments for a limited market as compared to the broader national market, which was contemplated by the federal and California GHG standards. 
Today’s proposal also confirms slower 
pace of development of ZEV technology and differences in projected manufacturing costs in states that have adopted these standards under section 177 as well as lower consumer demands for FCVs. The EPA also now expects that the pace of technological developments as it relates to infrastructure for FCVs will slow down. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00268 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243253 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
593‘‘Prediction is very difficult, especially if it’s 
about the future.’’ Attributed to Niels Bohr, Nobel 
laureate in Physics. The EPA is thus, proposing to find that 
CARB’s ZEV standards for MYs 2021 through 2025 are technologically infeasible in the lead time provided and therefore, that CARB’s ZEV standards are not consistent with section 202(a). 
As previously mentioned EPA is 
proposing to withdraw the grant of waiver for both standards on grounds that they are not consistent with section 202(a). In light of all the foregoing, the agency finds that is necessary and reasonable to reconsider the grant of waiver for CARB’s GHG and ZEV standards. EPA requests comments on all aspects of this proposal, especially specific costs for the ZEV requirements as it relates to MYs 2021 through 2025. 
4. States Cannot Adopt California’s GHG 
Standards for NAAQS Nonattainment Purposes Under Section 177 
As explained above, CAA section 177 
provides that other States, under certain circumstances and with certain conditions, may ‘‘adopt and enforce’’ standards that are ‘‘identical to the California standards for which a waiver has been granted for [a given] model year.’’ 42 U.S.C. 7507. The EPA proposes to determine that this section does not apply to CARB’s GHG standards. 
In this regard, the EPA notes that the 
section is titled ‘‘New motor vehicle emission standards in nonattainment areas’’ and that its application is limited to ‘‘any State which has [state implementation] plan provisions approved under this part’’—i.e., under 
CAA title I part D, which governs ‘‘Plan requirements for nonattainment areas.’’ 
Areas are only designated nonattainment with respect to criteria pollutants for which EPA has issued a NAAQS, and nonattainment SIPs are intended to assure that those areas attain the NAAQS. It would be illogical to require approved nonattainment SIP provisions as a predicate for allowing States to adopt California’s standards if states could use this authority to adopt California standards that addressed environmental problems other than nonattainment of criteria pollutant standards. Furthermore, the placement of section 177 in title I part D, rather than title II (the location of the California waiver provision) would make no sense if it functioned as a waiver applicable to all subjects, as does the California-focused provision under section 209(b), rather than as a provision specifically targeting criteria pollutants and nonattainment areas, as does the rest of title I part D. 
Therefore, the text, context, and 
purpose of section 177 suggest, and the EPA proposes to conclude, that it is limited to providing States the ability, 
under certain circumstances and with certain conditions, to adopt and enforce standards identical to those for which California has obtained a waiver— provided that those standards are designed to control criteria pollutants to address NAAQS nonattainment. EPA solicits comment on how and when this new interpretation should be adopted and implemented, if finalized ( e.g., 
whether EPA should adopt it as of the 
effective date of a final rule, or as of a 
later date, such as model year 2021 or calendar year 2020, in order to allow additional time for planning and transition). 
5. Severability and Judicial Review 
EPA considers its proposed decision 
on the appropriate federal standards for 
light duty greenhouse gas vehicles for MY 2021–2025 to be severable from its decision on withdrawing the ACC waiver, particularly with respect to the requirements of CAA 209(b)(1)(B). Our proposed interpretation of CAA 209(b)(1)(B), and our evaluation of the ACC waiver under that provision, does not depend on our decision to finalize, and a court’s decision to uphold, the light duty vehicles standards being proposed today under CAA 202(a). EPA solicits comment on the severability of these actions, particularly with respect to the other criteria of CAA 209(b). 
Section 307(b)(1) of the CAA provides 
in which Federal courts of appeal petitions of review of final actions by EPA must be filed. This section provides, in part, that petitions for review must be filed in the Court of Appeals for the District of Columbia Circuit if (i) the Agency action consists of ‘‘nationally applicable regulations promulgated, or final action taken, by the Administrator,’’ or (ii) such action is locally or regionally applicable, but ‘‘such action is based on a 
determination of nationwide scope or 
effect and if in taking such action the 
Administrator finds and publishes that such action is based on such a 
determination.’’ Separate and apart from 
whether a court finds this action to be 
locally or regionally applicable, the 
Administrator is proposing to find that 
any final action resulting from this rulemaking is based on a determination of ‘‘nationwide scope or effect’’ within the meaning of section 307(b)(1). 
This decision, when finalized, will 
affect persons in California and those manufacturers and/or owners/operators of new motor vehicles nationwide who must comply with California’s new motor vehicle requirements. For instance, manufacturers may generate credits in section 177 states as a means to satisfy those manufacturers’ 
obligations to comply with the mandate that a certain percentage of their vehicles sold in California be ZEV (or be credited as such from sales in section 177 States). In addition, because other states have adopted aspects of California’s ACC program this decision would also affect those states and those persons in such states, which are located in multiple EPA regions and federal circuits. For these reasons, EPA determines and finds for purposes of section 307(b)(1) that any final withdrawal action would be of national applicability, and also that such action would be based on a determination of nationwide scope or effect for purposes of section 307(b)(1). Pursuant to section 307(b)(1), judicial review of this final action may be sought only in the United States Court of Appeals for the District of Columbia Circuit. Judicial review of any final action may not be obtained in subsequent enforcement proceedings, pursuant to section 307(b)(2). 
VII. Impacts of the Proposed CAFE and 
CO
2Standards 
A. Overview 
New CAFE and CO 2standards will 
have a range of impacts. EPCA/EISA and NEPA require DOT to consider such impacts when making decisions about new CAFE standards, and the CAA requires EPA to do so when making decisions about new emissions standards. Like past rulemakings, today’s announcement is supported by the analysis of many potential impacts of new standards. Today’s announcement proposes new standards through model year 2026, explicitly estimates manufacturers’ responses to standards through model year 2029, and considers impacts, throughout those vehicles’ useful lives. The agencies do not know today what would actually 
come to pass decades from now under the proposed standards or under any of alternatives under consideration. The analysis is thus properly interpreted not as a forecast, but rather as an assessment—reflecting the best judgments regarding many different factors—of impacts that could occur.
593 
As discussed below, the analysis was conducted to explore the sensitivity of this assessment to a variety of potential changes in key analytical inputs ( e.g., 
fuel prices). 
This section summarizes various 
impacts of the preferred alternative ( i.e., 
the proposed standards) defined above 
in Section III. The no-action alternative 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00269 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243254 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
defined in Section IV provides the 
baseline relative to which all impacts are shown. Because the proposed standards (and other standards considered below), being of a ‘‘deregulatory’’ nature, are less stringent than the no-action alternative, all impacts are directionally opposite impacts reported in recent CAFE and CO
2rulemakings. For example, while 
past rulemakings reported positive values for fuel consumption avoided under new standards, today’s proposal reports negative values, as fuel consumption will be somewhat greater under today’s proposed standards than under standards defining the baseline no-action alternative. Reported negative values for avoided fuel consumption could also be properly interpreted as simply ‘‘additional fuel consumption.’’ Similarly, reported negative values for costs could be properly interpreted as ‘‘avoided costs’’ or ‘‘benefits,’’ and reported negative values for benefits could be properly interpreted as ‘‘foregone benefits’’ or ‘‘costs.’’ However, today’s notice retains reporting conventions consistent with past rulemakings, anticipating that, compared to other options, doing so will facilitate review by most stakeholders. 
Today’s analysis presents results for 
individual model years in two different ways. The first way is similar to past rulemakings and shows how manufacturers could respond in each model year under the proposed standards and each alternative covering MYs 2021/2–2026. The second, expanding on the information provided in past rulemakings, evaluates incremental impacts of new standards proposed for each model year, in turn. In past rulemaking analyses, NHTSA modeled year-by-year impacts under the aggregation of standards applied in all model years, and EPA modeled manufacturers’ hypothetical compliance with a single model years’ standards in that model year. Especially considering multiyear planning effects, neither approach provides a clear basis to attribute impacts to specific standards first introduced in each of a series of model years. For example, of the technology manufacturers applied in MY 2016, some would have been applied even under the MY 2014 standards, and some were likely applied to position manufacturers toward compliance with (including credit banking to be used toward) MY 2018 standards. Therefore, of the impacts attributable to the model year 2016 fleet, 
only a portion can be properly attributed to the MY 2016 standards, 
and the impacts of the MY 2016 standards involve fleets leading up and 
extending well beyond MY 2016. Considering this, the proposed standards were examined on an incremental basis, modeling each new model year’s standards over the entire span of included model years, using those results as a baseline relative to which to measure impacts attributable to the next model year’s standards. For example, incremental costs attributable to the standards proposed today for MY 2023 are calculated as follows: 
COST
Proposed,MY 2023 = (COST Proposed _
through _MY 2023 ¥COST No-Action _through _
MY 2023 —(COST Proposed _through _MY 
2022¥COST No-Action _through _MY 2022 ) 
Where: 
COST Proposed,MY 2023 : Incremental technology 
cost during MYs 2017–2030 and 
attributable to the standards proposed for MY 2023. 
COST
Proposed _through _MY 2022 : Technology cost 
for MYs 2017–2030 under standards proposed through MY 2022. 
COST
Proposed _through _MY 2023 : Technology cost 
for MYs 2017–2030 under standards proposed through MY 2023. 
COST
No-Action _through _MY 2022 : Technology cost 
for MYs 2017–2030 under no-action alternative standards through MY 2022. 
COST
No-Action _through _MY 2023 : Technology cost 
for MYs 2017–2030 under no-action alternative standards through MY 2023. 
Additionally, today’s analysis 
includes impacts on new vehicle sales volumes and the use ( i.e., survival) of 
vehicles of all model years, such that standards introduced in a model year produce impacts attributable to vehicles having been in operation for some time. For example, as modeled here, standards for MY 2021 will impact the prices of new vehicles starting in MY 2017, and those price impacts will affect the survival of all vehicles still in operation in calendar years 2017 and beyond (e.g., MY 2021 standards impact 
the operation of MY 2007 vehicles in calendar year 2027). Therefore, while past rulemaking analyses focused largely on impacts over the useful lives 
of the explicitly modeled fleets, much of today’s analysis considers all model years through 2029, as operated, throughout those vehicles’ useful lives. For some impacts, such as on technology penetration rates, average vehicle prices, and average vehicle ownership costs, the focus was on the useful life of the MY 2030 fleet, as the simulation of manufacturers’ technology application and credit use (when included in the analysis) continues to evolve after model year 2026, stabilizing by model year 2030. 
Effects were evaluated from four 
perspectives: The social perspective, the manufacturer perspective, the private perspective, and the physical perspective. The social perspective focuses on economic benefits and costs, setting aside economic transfers such as fuel taxes but including economic externalities such as the social cost of CO
2emissions. The manufacturer 
perspective focuses on average requirements and levels of performance (i.e., average fuel economy level and 
CO
2emission rates), compliance costs, 
and degrees of technology application. The private perspective focuses on costs of vehicle purchase and ownership, including outlays for fuel (and fuel taxes). The physical perspective focuses on national-scale highway travel, fuel consumption, highway fatalities, and greenhouse gas and criteria pollutant emissions. 
This analysis does not explicitly 
identify ‘‘co-benefits’’ from its proposed action to change fuel economy standards, as such a concept would include all benefits other than cost savings to vehicle buyers. Instead, it distinguishes between private benefits— which include economic impacts on vehicle manufacturers, buyers of new cars and light trucks, and owners (or users) of used cars and light trucks—and external benefits, which represent indirect benefits (or costs) to the remainder of the U.S. economy that stem from the proposal’s effects on the behavior of vehicle manufacturers, buyers, and users. In this accounting framework, changes in fuel use and safety impacts resulting from the proposal’s effects on the number of used vehicles in use represent an important component of its private benefits and costs, despite the fact that previous analyses have failed to recognize these effects. The agency’s presentation of private costs and benefits from its proposed action clearly distinguishes between those that would be experienced by owners and users of cars and light trucks produced during previous model years and those that would be experienced by buyers and users of cars and light trucks produced during the model years it would affect. Moreover, it clearly separates these into benefits related to fuel consumption and those related to safety consequences of vehicle use. This is more meaningful and informative than simply identifying all impacts other than changes in fuel savings to buyers of new vehicles as ‘‘co-benefits.’’ 
For the social perspective, the 
following effects for model years through 2029 as operated throughout those vehicles’ useful lives are summarized: 
•Technology Costs: Incremental cost, as 
expected to be paid by vehicle purchasers, of 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00270 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243255 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
fuel-saving technology beyond that added 
under the no-action alternative. 
•Welfare Loss: Loss of value to vehicle 
owners resulting from incremental increases in the numbers of strong and plug-in hybrid electric vehicles (strong HEVs or SHEVs, and PHEVs) and/or battery electric vehicles (BEVs), beyond increases occurring under the no-action alternative. The loss of value is a function of the factors that lead to different valuations for conventional and electric versions of similar-size vehicles ( e.g., 
differences in: travel range, recharging time versus refueling time, performance, and comfort). 
•Pre-tax Fuel Savings: Incremental 
savings, beyond those achieved under the no- action alternative, in outlays for fuel purchases, setting aside fuel taxes. 
•Mobility Benefit: Value of incremental 
travel, beyond that occurring under the no- 
action alternative. 
•Refueling Benefit: Value of incremental 
reduction, compared to the no-action alternative, of time spent refueling vehicles. 
•Non-Rebound Fatality Costs: Social 
value of additional fatalities, beyond those occurring under the no-action alternative, setting aside any additional travel attributable to the rebound effect. 
•Rebound Fatality Costs: Social value of 
additional fatalities attributable to the rebound effect, beyond those occurring under the no-action alternative. 
•Benefits Offsetting Rebound Fatality 
Costs: Assumed further value, offsetting 
rebound fatality costs, of additional travel attributed to the rebound effect. 
•Non-Rebound Non-Fatal Crash Costs: 
Social value of additional crash-related losses (other than fatalities), beyond those occurring under the no-action alternative, setting aside any additional travel attributable to the rebound effect. 
•Rebound Non-Fatal Crash Costs: Social 
value of additional crash-related losses (other than fatalities) attributable to the rebound effect, beyond those occurring under the no- action alternative. 
•Benefits Offsetting Rebound Non-Fatal 
Crash Costs: Assumed further value, offsetting rebound non-fatal crash costs, of additional travel attributed to the rebound effect. 
•Additional Congestion and Noise (Costs): 
Value of additional congestion and noise resulting from incremental travel, beyond that occurring under the no-action alternative. 
•Energy Security Benefit: Value of 
avoided economic exposure to petroleum price ‘‘shocks,’’ the avoided exposure resulting from incremental reduction of fuel consumption beyond that occurring under the no-action alternative. 
•Avoided CO
2Damages (Benefits): Social 
value of incremental reduction of CO 2 
emissions, compared to emissions occurring under the no-action alternative. 
•Other Avoided Pollutant Damages 
(Benefits): Social value of incremental 
reduction of criteria pollutant emissions, compared to emissions occurring under the no-action alternative. 
•Total Costs: Sum of incremental 
technology costs, welfare loss, fatality costs, non-fatal crash costs, and additional 
congestion and noise costs. 
•Total Benefits: Sum of pretax fuel 
savings, mobility benefits, refueling benefits, Benefits Offsetting Rebound Fatality Costs, Benefits Offsetting Rebound Non-Fatal Crash Costs, energy security benefits, and benefits from reducing emissions of CO
2, other GHGs, 
and criteria pollutants. 
•Net Benefits: Total benefits minus total 
costs. 
•Retrievable Electrificaiton Costs: The 
portion of HEV, PHEV, and BEV technology costs which can be passed onto consumers, using the willingness to pay analysis described above. 
•Electrification Tax Credits: Estimates of 
the portion of HEV, PHEV, and BEV technology costs which are covered by federal or state tax incentives. 
•Irretreivable Electrification Costs: The 
portion of HEV, PHEV, and BEV technology costs OEM’s must either absorb as a profit loss, or cross-subsidize with the prices of internal combustion engine (ICE) vehicles. 
•Total Electrification Costs: Total 
incremental technology costs attributable to HEV, PHEV, or BEV vehicles. 
For the manufacturer perspective, the 
following effects for the aggregation of 
model years 2017–2029 are summarized: 
•Average Required Fuel Economy: 
Average of manufacturers’ CAFE 
requirements for indicated fleet(s) and model year(s). 
•Percent Change in Stringency from 
Baseline: Percentage difference between 
averages of fuel economy requirements under no-action and indicated alternatives. 
•Average Required Fuel Economy: 
Industry-wide average of fuel economy levels achieved by indicated fleet(s) in indicated model year(s). 
•Percent Change in Stringency from 
Baseline: Percentage difference between 
averages of fuel economy levels achieved under no-action and indicated alternatives. 
•Total Technology Costs ($b): Cost of fuel- 
saving technology beyond that applied under no-action alternative. 
•Total Civil Penalties ($b): Cost of civil 
penalties (for the CAFE program) beyond those levied under no-action alternative. 
•Total Regulatory Costs ($b): Sum of 
technology costs and civil penalties. 
•Sales Change (millions): Change in 
number of vehicles produced for sale in U.S., relative to the number estimated to be produced under the no-action alternative. 
•Revenue Change ($b): Change in total 
revenues from vehicle sales, relative to total revenues occurring under the no-action alternative. 
•Curb Weight Reduction: Reduction of 
average curb weight, relative to MY 2016. 
•Technology Penetration Rates: MY 2030 
average technology penetration rate for 
indicated ten technologies (three engine technologies, advanced transmissions, and six degrees of electrification). 
•Average Required CO
2: Average of 
manufacturers’ CO 2requirements for 
indicated fleet(s) and model year(s). 
•Percent Change in Stringency from 
Baseline: Percentage difference between averages of CO 2requirements under no- 
action and indicated alternatives. 
•Average Achieved CO 2: Average of 
manufacturers’ CO 2emission rates for 
indicated fleet(s) and model year(s). 
For the private perspective, the 
following effects for the MY 2030 fleet 
are summarized: 
•Average Price Increase: Average increase 
in vehicle price, relative to the average 
occurring under the no-action alternative. 
•Welfare Loss (Costs): Average loss of 
value to vehicle owners resulting from incremental increases in the numbers of strong HEVs, PHEVs) and/or BEVs, beyond increases occurring under the no-action alternative. The loss of value is a function of the factors that lead to different valuations for conventional and electric versions of similar-size vehicles (e.g., differences in: 
Travel range, recharging time versus refueling time, performance, and comfort). 
•Ownership Costs: Average increase in 
some other costs of vehicle ownership (taxes, fees, financing), beyond increase occurring under no-action alternative. 
•Fuel Savings: Average of fuel outlays 
(including taxes) avoided over a vehicles’ expected useful lives, compared to outlays occurring under no-action alternative. 
•Mobility Benefit: Average incremental 
value of additional travel over average vehicles’ useful lives, compared to travel occurring under no-action alternative. 
•Refueling Benefit: Average incremental 
value of avoided time spent refueling over average vehicles’ useful lives, compared to time spent refueling under no-action alternative. 
•Total Costs: Sum of average price 
increase, welfare loss, and ownership costs. 
•Total Benefits: Sum of fuel savings, 
mobility benefit, and refueling benefit. 
•Net Benefits: Total benefits minus total 
costs. 
For the physical perspective, the 
following effects for model years 
through 2029 as operated throughout those vehicles’ useful lives are summarized: 
•Greenhouse gases include carbon 
dioxide (CO 2), methane (CH 4), and nitrous 
oxide (N 2O), and values are reported 
separately for vehicles (tailpipe) and 
upstream processes (combining fuel production, distribution, and delivery) and 
shown as reductions relative to the no-action 
alternative. 
•Criteria pollutants include carbon 
monoxide (CO), volatile organic compounds (VOC), nitrogen oxides (NO
X), sulfur dioxide 
(SO 2) and particulate matter (PM), and values 
are shown as reductions relative to the no- action alternative. 
•Fuel consumption aggregates all fuels, 
with electricity, hydrogen, and compressed natural gas (CNG) included on a gasoline- equivalent-gallon (GEG) basis, and values are shown as reductions relative to the no-action alternative. 
•VMT, with rebound (billion miles): 
Increase in highway travel (as vehicle miles traveled), relative to the no-action alternative, 
and including the rebound effect. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00271 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243256 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
594Compliance and Effects Modeling System, 
National Highway Traffic Safety Administration, 
https://www.nhtsa.gov/corporate-average-fuel- economy/compliance-and-effects-modeling-system (last visited June 25, 2018). 
595These tools, available at the same location, are 
scripts executed using R, a free software environment for statistical computing. R is available through https://www.r-project.org/. •VMT, without rebound (billion miles): 
Increase in highway travel (as vehicle miles 
traveled), relative to the no-action alternative, and excluding the rebound effect. 
•Fatalities, with rebound: Increase in 
highway fatalities, relative to the no-action alternative, and including the rebound effect. 
•Fatalities, without rebound: Increase in 
highway fatalities, relative to the no-action alternative, and excluding the rebound effect. 
•Fuel Consumption, with rebound (billion 
gallons): Reduction of fuel consumption, 
relative to the no-action alternative, and including the rebound effect. 
•Fuel Consumption, without rebound 
(billion gallons): Reduction of fuel consumption, relative to the no-action alternative, and excluding the rebound effect. 
Below, this section tabulates results 
for each of these four perspectives and 
does so separately for the proposed CAFE and CO
2standards. More detailed 
results are presented in the Preliminary Regulatory Impact Analysis (PRIA) accompanying today’s notice, and additional and more detailed analysis of environmental impacts for CAFE regulatory alternatives is provided in the corresponding Draft Environmental Impact Statement (DEIS). Underlying CAFE model output files are available (along with input files, model, source code, and documentation) on NHTSA’s website.
594Summarizing and tabulating 
results for presentation here involved considerable ‘‘off model’’ calculations (e.g., to combine results for selected 
model years and calendar years, and to combine various components of social and private costs and benefits); tools Volpe Center staff used to perform these calculations are also available on NHTSA’s website.
595 
While the National Environmental 
Policy Act (NEPA) requires NHTSA to prepare an EIS documenting estimating environmental impacts of the regulatory alternatives under consideration in CAFE rulemakings, NEPA does not require EPA to do so for EPA rulemakings. CO
2standards for each 
regulatory alternative being harmonized as practical with corresponding CAFE standards, environmental impacts of GHG standards should be directionally identical and similar in magnitude to those of CAFE standards. Nevertheless, in this section, following the series of tables below, today’s announcement provides a more detailed analysis of estimated impacts of the proposed CAFE and CO
2standards. Results 
presented herein for the CAFE standards differ slightly from those presented in the DEIS; while, as discussed above, EPCA/EISA requires that the Secretary determine the maximum feasible levels of CAFE standards in manner that, as presented here, sets aside the potential use of CAFE credits or application of alternative fuels toward compliance with new standards, NEPA does not impose such constraints on analysis presented in corresponding DEISs, and the DEIS presents results of an ‘‘unconstrained’’ analysis that considers manufacturers’ potential application of alternative fuels and use of CAFE credits. 
In terms of all estimated impacts, 
including estimated costs and benefits, results of today’s analysis are different for CAFE and CO
2standards. 
Differences arise because, even when the mathematical functions defining fuel economy and CO
2targets are 
‘‘harmonized,’’ surrounding regulatory provisions may not be. For example, while both CAFE and CO
2standards 
allow credits to be transferred between fleets and traded between manufacturers, EPCA/EISA places explicit and specific limits on the use of such credits, such as by requiring that each domestic passenger car fleet meet a minimum CAFE standard (as discussed above). The CAA provides no specific direction regarding CO
2 
standards, and while EPA has adopted many regulatory provisions harmonized with specific EPCA/EISA provisions (e.g., separate standards for passenger 
cars and light trucks), EPA has not adopted all such provisions. For example, EPA has not adopted the EPCA/EISA provisions limiting transfers between regulated fleet or requiring separate compliance by domestic and imported passenger car fleets. Such differences introduce differences between impacts estimated under CAFE standards and under CO
2standards. 
Also, as mentioned above, Congress has required that new CAFE standards be considered in a manner that sets aside the potential use of CAFE credits and the potential additional application of alternative fuel vehicles (such as electric vehicles) during the model years under consideration. Congress has provided no corresponding direction regarding the analysis of potential CO
2standards, and 
today’s analysis does consider these potential responses to CO
2standards. 
As mentioned above, analysis was 
conducted to examine the sensitivity of results to changes in key inputs. Following the detailed consideration of potential environmental impacts, this section concludes with a tabular summary of results of this sensitivity analysis. 
B. Impacts of Proposed Standards on 
Requirements, Performance, and Costs to Manufacturers in Specific Model Years 
As mentioned above, impacts are 
presented from two different perspectives for today’s proposal. From either perspective, overall impacts are the same. The first perspective, following the approach taken by NHTSA in past CAFE rulemakings, examines impacts of the overall proposal—i.e., the entire series of year- 
by-year standards—on each model year. This perspective is especially relevant to understanding how the overall proposal may impact manufacturers in terms of year-by-year compliance, technology pathways, and costs. The second, presented below in Section VII.C, provides a clearer characterization of the incremental impacts attributable to standards introduced in each successive model year. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00272 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243257 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00273 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.164</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243258 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00274 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.165</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243259 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00275 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.166</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243260 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00276 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.167</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243261 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00277 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.168</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243262 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00278 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.169</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243263 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00279 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.170</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243264 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00280 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.171</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243265 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00281 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.172</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243266 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00282 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.173</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243267 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00283 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.174</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243268 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00284 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.175</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243269 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00285 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.176</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243270 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00286 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.177</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243271 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00287 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.178</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243272 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00288 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.179</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243273 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00289 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.180</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243274 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00290 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.181</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243275 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00291 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.182</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243276 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00292 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.183</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243277 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00293 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.184</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243278 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00294 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.185</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243279 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00295 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.186</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243280 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00296 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.187</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243281 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00297 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.188</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243282 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00298 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.189</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243283 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00299 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.190</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243284 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00300 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.191</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243285 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00301 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.192</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243286 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00302 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.193</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243287 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00303 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.194</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243288 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00304 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.195</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243289 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00305 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.196</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243290 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00306 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.197</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243291 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00307 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.198</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243292 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00308 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.199</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243293 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00309 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.200</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243294 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00310 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.201</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243295 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00311 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.202</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243296 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00312 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.203</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243297 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00313 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.204</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243298 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00314 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.205</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243299 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00315 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.206</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243300 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00316 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.207</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243301 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00317 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.208</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243302 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00318 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.209</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243303 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00319 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.210</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243304 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00320 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.211</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243305 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00321 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.212</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243306 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00322 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.213</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243307 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00323 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.214</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243308 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
C. Incremental Impacts of Standards 
Proposed for Each Model Year 
As mentioned above, impacts are 
presented from two different 
perspectives for today’s proposal. From either perspective, overall impacts are the same. The first perspective, taken 
above in VI.A, examines impacts of the overall proposal — i.e., the entire series 
of year-by-year standards — on each 
model year. The second perspective, presented here, provides a clearer characterization of the incremental impacts attributable to standards introduced in each successive model year. For example, the standards proposed for MY 2023 are likely to impact manufacturers’ application of 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00324 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.215</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243309 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
596Available at https://www.nhtsa.gov/corporate- 
average-fuel-economy/compliance-and-effects- 
modeling-system. technology in model years prior to MY 
2023, as well as model years after MY 2023. By conducting analysis that successively introduces standards for each MY, in turn, isolates the incremental impacts attributable to new standards introduced in each MY, considering the entire span of MYs (1977–2029) included in the underlying modeling, throughout those vehicles’ useful lives. Tables appearing below summarize results as aggregated across these model and calendar years. Underlying model output files
596report 
physical impacts and specific monetized costs and benefits attributable to each model year in each calendar (thus providing information needed to, for example, differentiate between impacts attributable to the MY 1977–2016 and MY 2017–2029 cohorts). 
The PRIA presents costs and benefits for individual model years (with MY’s 1977–2016 in a single bucket) for the preferred alternative. 
1. What are the Social Costs and 
Benefits of the Proposed Standards? 
(a) CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00325 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.216</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243310 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00326 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.217</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243311 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00327 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.218</GPH> EP24AU18.219</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243312 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
(b) CO 2Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00328 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.220</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243313 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00329 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.221</GPH> EP24AU18.222</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243314 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
2. What are the private costs and 
benefits of the proposed standards, relative to the no-action alternative? 
(a) What are the impacts on producers 
of new vehicles? 
(b) CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00330 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.223</GPH> EP24AU18.224</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243315 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00331 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.225</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243316 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00332 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.226</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243317 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00333 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.227</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243318 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00334 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.228</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243319 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00335 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.229</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243320 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
(c) CO 2Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00336 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.230</GPH> EP24AU18.231</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243321 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00337 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.232</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243322 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00338 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.233</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243323 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
(d) What are the impacts on buyers of 
new vehicles? 
(e) CAFE Standards 
(f) CO 2Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00339 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.234</GPH> EP24AU18.235</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243324 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
D. What are the Energy and 
Environmental Impacts? 
Today’s proposal directly involves the 
fuel economy and average CO 2 
emissions of light-duty vehicles, and the proposal is expected to most directly and significantly impact national fuel consumption and CO
2emissions. Fuel 
economy and CO 2emissions are so 
closely related that it is expected the impacts on national fuel consumption 
and national CO 2emissions will track in 
virtual lockstep with each other. 
Today’s proposal does not directly 
involve pollutants such as carbon monoxide, smog-forming pollutants 
(nitrogen oxides and unburned hydrocarbons), final particles, or ‘‘air toxics’’ (e.g., formaldehyde, 
acetaldehyde, benzene). While today’s proposal is expected to indirectly 
impact such emissions (by reducing travel demand and accelerating fleet turnover to newer and cleaner vehicles on one hand while, on the other, increasing activity at refineries and in the fuel distribution system), it is expected that these impacts will be much smaller than impacts on fuel use and CO
2emissions because standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00340 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.236</GPH> EP24AU18.237</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243325 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
for these other pollutants are 
independent of those for CO 2emissions. 
Following decades of successful 
regulation of criteria pollutants and air toxics, modern vehicles are already vastly cleaner than in the past, and it is expected that new vehicles will continue to improve. For example, the following chart shows trends in new vehicles’ emission rates for volatile organic compounds (VOCs) and 
nitrogen oxides (NO
X) — the two motor 
vehicle criteria pollutants that contribute to the formation of smog. 
Because new vehicles are so much 
cleaner than older models, it is expected 
that under any of the alternatives considered here for fuel economy and CO
2standards, emissions of smog- forming pollutants would continue to decline nearly identically over the next two decades. The following chart shows estimated total fuel consumption, CO
2 
emissions, and smog-forming emissions under the baseline and proposed standards (CAFE standards — trends for CO
2standards would be very similar), 
using units that allow the three to be shown together: 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00341 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.238</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243326 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
While the differences in fuel use and 
CO 2emissions trends under the baseline 
and proposed standards are clear, the corresponding difference in smog- 
forming emissions trends is too small to discern. For these three measures, the following table shows percentage differences between the amounts shown above: 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00342 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.239</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243327 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
597Impacts and U.S. emissions of GHGs are 
discussed at greater length in EPA’s 2018 Inventory of U.S. Greenhouse Gas Emissions and Sinks (EPA 
430–R–18–003) (Apr. 12, 2018), available at https:// www.epa.gov/sites/production/files/2018-01/ 
documents/2018_ complete_ report.pdf. 
As indicated, for most of the coming 
two decades, it is estimated that, even 
as fuel consumption and CO 2emissions 
would increase under the proposed standards (compared to fuel consumption and CO
2emissions under 
the baseline standards), smog-forming pollution would actually decrease. During the two decades shown above, it is estimated that the proposed standards would increase aggregate fuel consumption and CO
2emissions by 
about four percent but would decrease 
aggregate smog-forming pollution by about 0.1% (because impacts of the reduced travel and accelerated fleet turnover would outweigh those of increased refining and fuel distribution). 
As the analysis affirms, while fuel 
economy and CO
2emissions are two 
sides (or, arguably, the same side) of the same coin, fuel economy and CO
2are 
only incidentally related to pollutants such as smog, and any positive or 
negative impacts of today’s notice on these other air quality problems would most likely be far too small to observe. 
The remainder of this section 
summarizes the impacts on fuel consumption and emissions for both the proposed CAFE standards and the proposed CO
2standards. 
1. Energy and Warming Impacts 
Section V discusses, among other 
things, the need of the Nation to conserve energy, providing context for the estimated impacts on national-scale fuel consumption summarized below. Corresponding to these changes in fuel consumption, the agencies estimate that today’s proposal will impact CO
2 
emissions. CO 2is one of several 
greenhouse gases that absorb infrared radiation, thereby trapping heat and making the planet warmer. The most important greenhouse gases directly emitted by human activities include 
carbon dioxide (CO
2), methane (CH 4), 
nitrous oxide (N 2O), and several 
fluorine-containing halogenated substances. Although CO
2, CH 4, and 
N2O occur naturally in the atmosphere, 
human activities have changed their atmospheric concentrations. From the pre-industrial era (i.e., ending about 
1750) to 2016, concentrations of these greenhouse gases have increased globally by 44, 163, and 22%, respectively.
597The Draft 
Environmental Impact Analysis (DEIS) accompanying today’s notice discusses potential impacts of greenhouse gases at greater length, and also summaries analysis quantifying some of these impacts (e.g., average temperatures) for 
each of the considered regulatory alternatives. 
(a) CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00343 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.240</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243328 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
(b) CO 2Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00344 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.241</GPH> EP24AU18.242</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243329 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
2. How would the proposal impact 
emissions of criteria and toxic pollutants? 
Although this proposal focuses on 
standards for fuel economy and CO
2, it 
will also have an impact on criteria and air toxic pollutant emissions, although as discussed above, it is expected that incremental impacts on criteria and air 
toxic pollutant emissions would be too small to observe under any of the regulatory alternatives under consideration. Nevertheless, the following sections detail the criteria pollutant and air toxic inventory impacts of this proposal; the methodology used to calculate those impacts; the health and environmental effects associated with the criteria and toxic air pollutants that are being impacted by this proposal; the potential impact of this proposal on concentrations of criteria and air toxic pollutants in the ambient air; and other 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00345 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.243</GPH> EP24AU18.244</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243330 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
598The agencies have employed the same 
methodology in this rulemaking to estimate the 
effect of each alternative on emissions of PM and other criteria pollutants emissions as they have previously applied in the other rulemakings under the National Program. Briefly, emissions from 
vehicle use are estimated for each calendar year of the analysis period by applying emission rates per vehicle-mile of travel to estimates of VMT for cars and light trucks produced during each model year making up the vehicle fleet. These emission rates are derived from EPA’s Motor Vehicle Emissions Simulator (MOVES); they reflect normal increases in vehicles’ emission rates as they age and accumulate mileage, as well as adopted and pending vehicle emission standards and regulations on fuel composition. ‘‘Upstream’’ emissions from crude oil production, fuel refining, and fuel distribution are estimated from the total energy content of fuels produced and consumed (gasoline, diesel, ethanol, and electricity), using separate emission factors per unit of fuel energy for each phase of fuel production and distribution derived from Argonne National Laboratories’ Greenhouse Gases and Regulated Emissions in Transportation (GREET) fuel cycle model. This procedure accounts for differences in domestic emissions associated with refining fuel from imported and domestically- supplied crude petroleum, as well as from importing fuel that has been refined outside the U.S. Economic damages caused by emissions from vehicle use and from fuel production and distribution are monetized using different per-ton values, which reflect differences in the locations where emissions occur and resulting variation in population exposure to their potential adverse health effects. However, we note that in some other rules affecting tailpipe emissions of criteria pollutants, EPA has employed more detailed methods for estimating emissions associated with different phases of fuel production and distribution, and has also used more detailed estimates of their per-ton health damage costs that reflect variation in population exposure to emissions occurring during different phases of fuel production and distribution. The agencies will consider whether to employ these more detailed procedures in their analysis supporting the final rule. 
599While estimates for CY 2025 and 2035 are 
shown here, estimates through 2050 are shown in PRIA Chapter 5. unquantified health and environmental 
effects. 
Today’s analysis reflects the 
combined result of several underlying impacts, all discussed above. CAFE and CO
2standards are estimated to impacts 
new vehicle prices, fuel economy levels, and CO
2emission rates. These changes 
are estimated to impact the size and composition of the new vehicle fleet and to impact the retention of older vehicles (i.e., vehicle survival and 
scrappage) that tend to have higher criteria and toxic pollutant emission rates. Along with the rebound effect, these lead to changes in the overall amount of highway travel and the distribution among different vehicles in the on-road fleet. Vehicular emissions depend on the overall amount of highway travel and the distribution of that travel among different vehicles, and emissions from ‘‘upstream’’ processes (e.g., petroleum refining, electricity 
generation) depend on the total consumption of different types of fuels for light-duty vehicles. 
(a) Impacts 
In addition to affecting fuel 
consumption and emissions of 
greenhouse gases, this rule would influence ‘‘non-GHG’’ pollutants, i.e., 
‘‘criteria’’ air pollutants and their precursors, and air toxics. The proposal would affect emissions of carbon monoxide (CO), fine particulate matter (PM
2.5), sulfur dioxide (SO X), volatile 
organic compounds (VOC), nitrogen oxides (NO
X), benzene, 1,3-butadiene, 
formaldehyde, acetaldehyde, and acrolein. Consistent with the evaluation conducted for the Environmental Impact Statement accompanying this NPRM, the agency analyzed criteria air pollutant impacts in 2025 and 2035 (as a representation of future program impacts). Estimates of these non-GHG emission impacts are shown by pollutant in Table VII–80 through Table VII–87 and are broken down by the two drivers of these changes: (a) ‘‘downstream’’ emission changes, reflecting the estimated effects of VMT rebound (discussed in Chapter 8.7 of the PRIA), changes in vehicle fleet age, changes in vehicle emission standards, and changes in fuel consumption; and (b) ‘‘upstream’’ emission increases because of increased refining and distribution of motor vehicle gasoline relative to the baseline. Program impacts on criteria and toxics emissions are discussed below, followed by individual discussions of the methodology used to calculate each of these three sources of 
impacts.
598 
As shown in Table VII–80, it is 
estimated in 2025 the light duty vehicle CAFE scenarios would result in reductions of NO
X, VOC, and CO, and 
increases in PM 2.5and SOx.599For NO x, 
VOC, and CO, it is estimated net reductions result from lower downstream, or tailpipe emissions in the scenarios evaluated. This is a result of reduced VMT rebound as well as fewer older vehicles in the scenarios as compared to the baseline. Because the scenarios result in greater fuel consumption than the baseline, however, upstream emissions associated with fuel refining and distribution increase for all pollutants in all scenarios as compared to the baseline. Tailpipe emissions reductions for NOx, VOC, and CO more than compensate for this increase in 2025. PM
2.5and SO x, 
tailpipe emissions reductions are not great enough to compensate for 
increased emissions from fuel refining and distribution and therefore an overall increase in total PM
2.5and SO xis seen 
in 2025. Similar results can be seen in Table VII–81 which shows results for the CO
2target scenarios. 
In 2035, Table VII–82 shows 
decreases in total CO result from all CAFE scenarios, while NO
X, VOC, SO 2, 
and PM 2.5increase. Tailpipe CO 
emissions reductions more than offset increases in upstream CO emissions. For NO
X, VOC, SO 2, and PM 2.5however, 
upstream emissions increases are not offset by tailpipe NO
X, VOC, SO 2, and 
PM 2.5emissions reductions. Similar 
results can be seen in the CO 2target 
scenarios for 2035 shown in Table VII– 83, with the exception that NO
X 
emission decrease for scenarios 1–4 and increase for scenarios 5–8. For all criteria pollutants, the overall impact of the proposed program would be small compared to total U.S. inventories across all sectors. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00346 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243331 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00347 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.245</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243332 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
As shown in Table VII–84 through 
Table VII–87, it is estimated that the 
proposed program would result in small changes for air toxic emissions compared to total U.S. inventories 
across all sectors. In 2025, it is estimated the scenarios evaluated would reduce total acetaldehyde, acrolein, benzene, butadiene, and formaldehyde, toxics as compared to the baseline. This 
result is caused by greater VMT rebound miles assumed in the augural scenario and fewer rebound VMT in scenarios 1– 8, and fewer older vehicles in the 
scenarios as compared to the baseline. Similarly, in 2035, acetaldehyde, benzene, butadiene, acrolein, and formaldehyde would all be reduced as compared to the baseline. As is the case 
with criteria emissions, upstream toxic emissions generally increase in the evaluated scenarios as compared to the baseline because of the greater amount of gasoline and diesel being refined and distributed. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00348 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.246</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243333 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00349 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.247</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243334 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
600See 79 FR 23414 (April 28, 2014). EPA’s Tier 
3 emissions standards included standards for vehicle emissions and the sulfur content of 
gasoline. 
(b) Methodology 
For the downstream analysis, 
emission factors in grams per mile for 
VOC, CO, NO X, PM 2.5, and air toxics by 
vehicle model year and age were taken from the current version of the EPA ‘‘Motor Vehicle Emission Simulator’’ (MOVES2014a) and multiplied in the CAFE model by assumed VMT to estimate mass VOC, CO, NO
X, PM 2.5, 
and air toxics emissions. Additional emissions from light duty cars and 
trucks attributable to the rebound effect were also calculated using the CAFE model. A more complete discussion of the inputs, methodology, and results is contained in PRIA Chapter 6. This proposal also assumes implementation of EPA’s Tier 3 emission standards.
600 For a more detailed description of the 
method used to estimate emissions, please refer to pages 104–106 of the CAFE model documentation. 
For the purposes of this emission 
analysis, it is assumed that all gasoline in the timeframe of the analysis is blended with 10% ethanol (E10). While electric vehicles have zero tailpipe 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00350 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.248</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243335 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
601Greenhouse Gas, Regulated Emissions, and 
Energy Use in Transportation model (GREET), U.S. 
Department of Energy, Argonne National Laboratory, https://greet.es.anl.gov/. 602U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. Figure 3–1. 
603Regulatory definitions of PM size fractions, 
and information on reference and equivalent methods for measuring PM in ambient air, are provided in 40 CFR parts 50, 53, and 58. With regard to national ambient air quality standards (NAAQS) which provide protection against health and welfare effects, the 24-hour PM
10standard 
provides protection against effects associated with short-term exposure to thoracic coarse particles (i.e., PM
10–2.5 ). emissions, it is assumed that 
manufacturers will plan for these vehicles in their regulatory compliance strategy for non-GHG emissions standards, and will not over-comply with those standards. Because the Tier 3 emissions standards are fleet-average standards (for all pollutants except 
formaldehyde and PM
2.5), it is assumed 
that if a manufacturer introduces EVs into its fleet, that it would correspondingly compensate through changes to vehicles elsewhere in its fleet, rather than meet an overall lower fleet-average emissions level. Consequently, no tailpipe pollutant benefit (other than CO
2,formaldehyde, 
and PM 2.5) is assumed. The analysis 
does not estimate evaporative emissions from light-duty vehicles. Other factors which may impact downstream non- GHG emissions, but are not estimated in this analysis, include the potential for decreased criteria pollutant emissions because of increased air conditioner efficiency; reduced refueling emissions because of less frequent refueling events and reduced annual refueling volumes resulting from the CO
2standards; and 
increased hot soak evaporative emissions because of the likely increase in number of trips associated with VMT rebound modeled in this proposal. In all, these additional analyses would likely result in small changes relative to the national inventory. 
To determine the impacts of increased 
fuel production on upstream emissions, the impact of increased gasoline consumption by light-duty vehicles on the extraction and transportation of crude oil, refining of crude oil, and distribution and storage of finished gasoline was estimated. To assess the resulting increases in domestic emissions, the fraction of increased gasoline consumption that would be supplied by additional domestic refining of gasoline, and the fraction of that gasoline that would be refined from domestic crude oil was estimated. Using NEMS, it was estimated that 50% of increased gasoline consumption would be supplied by increased domestic refining and that 90% of this additional refining would use imported crude petroleum. Emission factors for most upstream emission sources are based on the DOE Argonne National Laboratory’s GREET 2017 model,
601but emission 
factors developed by EPA were relied on for the air toxics estimated in this analysis: benzene, 1,3-butadiene, acetaldehyde, acrolein, and formaldehyde. These emission factors came from the MOVES 2014a model and were incorporated into the CAFE model. 
Emission factors for electricity 
upstream emissions were also based on GREET 2017. GREET allows the user to either select a region of the country for the electricity upstream emissions or to use the U.S. average of electricity emissions. The regional emission factors reflect the specific mix of fuels used to generate electricity in the selected region. The U.S. mix provides an average of electricity-related emissions (in grams per million Btu) in the U.S. in a given calendar year. The GREET 2017 U.S. mix emission factors were used for the analysis. In order to capture projected changes in upstream emissions over time, upstream emission factors for gasoline, diesel, and electricity were taken from the GREET 2017 model in five year increments, beginning in 1995 and ending in 2040. 
For the downstream analysis of 
emissions, there are a number of uncertainties associated with the method, such as: Emission factors are based on samples of tested vehicles and these samples may not represent average emissions for the full in-use fleet; and there is considerable uncertainty in estimating total vehicle use (VMT). For the upstream analysis of emissions, there are uncertainties related to the projection of emissions associated with fossil fuel extraction, refining, and mode split for transportation of fuels. In addition, projections for electricity- related upstream emissions are based on assumptions about the fuels and technologies used to generate electricity which may not represent actual conditions through 2050. 
E. Health Effects of Non-GHG Pollutants 
This section discusses health effects 
associated with exposure to some of the 
criteria and air toxic pollutants impacted by the proposed vehicle standards. 
1. Particulate Matter 
(a) Background 
Particulate matter is a highly complex 
mixture of solid particles and liquid 
droplets distributed among numerous atmospheric gases which interact with solid and liquid phases. Particles range in size from those smaller than 1 nanometer (10–9 meter) to more than 100 micrometers (mm, or 10–6 meter) in diameter (for reference, a typical strand of human hair is 70 mm in diameter and 
a grain of salt is approximately 100 mm). Atmospheric particles can be grouped into several classes according to their aerodynamic and physical sizes. Generally, the three broad classes of 
particles include ultrafine particles (UFPs, generally considered as particulates with a diameter less than or equal to 0.1 mm [typically based on physical size, thermal diffusivity or electrical mobility]), ‘‘fine’’ particles (PM
2.5; particles with a nominal mean 
aerodynamic diameter less than or equal to 2.5 mm), and ‘‘thoracic’’ particles 
(PM
10; particles with a nominal mean 
aerodynamic diameter less than or equal to 10 mm).
602Particles that fall within 
the size range between PM 2.5and PM 10, 
are referred to as ‘‘thoracic coarse particles’’ (PM
10–2.5 , particles with a 
nominal mean aerodynamic diameter less than or equal to 10 mm and greater 
than 2.5 mm). EPA currently has standards that regulate PM
2.5and 
PM 10.603 
Particles span many sizes and shapes 
and may consist of hundreds of different chemicals. Particles are emitted directly from sources and are also formed through atmospheric chemical reactions; the former are often referred to as ‘‘primary’’ particles, and the latter as ‘‘secondary’’ particles. Particle concentration and composition varies by time of year and location, and, in addition to differences in source emissions, is affected by several weather-related factors, such as temperature, clouds, humidity, and wind. A further layer of complexity comes from particles’ ability to shift between solid/liquid and gaseous phases, which is influenced by concentration and meteorology, especially temperature. 
Fine particles are produced primarily 
by combustion processes and by transformations of gaseous emissions (e.g., sulfur oxides (SO
X), oxides of 
nitrogen, and volatile organic compounds (VOC)) in the atmosphere. The chemical and physical properties of PM
2.5may vary greatly with time, 
region, meteorology, and source category. Thus, PM
2.5may include a 
complex mixture of different components including sulfates, nitrates, organic compounds, elemental carbon and metal compounds. These particles can remain in the atmosphere for days 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00351 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243336 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
604U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. 
605The ISA also evaluated evidence for 
individual PM components but did not reach causal determinations for components. 
606The causal framework draws upon the 
assessment and integration of evidence from across epidemiological, controlled human exposure, and toxicological studies, and the related uncertainties 
that ultimately influence our understanding of the evidence. This framework employs a five-level hierarchy that classifies the overall weight of evidence and causality using the following categorizations: Causal relationship, likely to be causal relationship, suggestive of a causal relationship, inadequate to infer a causal relationship, and not likely to be a causal relationship (U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Table 1–3). 
60778 FR 3103–3104 (Jan. 15, 2013). 
60877 FR 38906–38911 (June 29, 2012). 
609These causal inferences are based not only on 
the more expansive epidemiological evidence available in this review but also reflect 
consideration of important progress that has been made to advance our understanding of a number of potential biologic modes of action or pathways for PM-related cardiovascular and respiratory effects (U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Chapter 5). 
61078 FR 3103–3104 (Jan. 15, 2013). 
611U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Chapter 6 (Section 6.5) and Chapter 7 (Section 7.6). 
612U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 6. 613U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 6. 
614U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 7. 
615U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. pg 2–13. 
616U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. pg 2–26. to weeks and travel hundreds to 
thousands of kilometers. 
(b) Health Effects of PM 
Scientific studies show exposure to 
ambient PM is associated with a broad 
range of health effects. These health effects are discussed in detail in the 2009 Integrated Science Assessment for Particulate Matter (PM ISA), which was used as the basis of the 2012 NAAQS.
604 
The PM ISA summarizes health effects evidence for short- and long-term exposures to PM
2.5, PM 10–2.5 , and 
ultrafine particles.605The PM ISA 
concludes that human exposures to ambient PM
2.5are associated with a 
number of adverse health effects and characterizes the weight of evidence for broad health categories ( e.g., 
cardiovascular effects, respiratory effects, etc.).
606The discussion below 
highlights the PM ISA’s conclusions pertaining to health effects associated with both short- and long-term PM exposures. Further discussion of health effects associated with PM can also be found in the rulemaking documents for the most recent review of the PM NAAQS completed in 2012.
607 608  
EPA has concluded that ‘‘a causal 
relationship exists’’ between both long- and short-term exposures to PM
2.5and 
premature mortality and cardiovascular effects and that ‘‘a causal relationship is likely to exist’’ between long- and short- term PM
2.5exposures and respiratory 
effects. Further, there is evidence ‘‘suggestive of a causal relationship’’ between long-term PM
2.5exposures and 
other health effects, including developmental and reproductive effects (e.g., low birth weight, infant mortality) 
and carcinogenic, mutagenic, and genotoxic effects (e.g., lung cancer 
mortality).
609 As summarized in the final rule 
promulgating the 2012 PM NAAQS, and discussed extensively in the 2009 PM ISA, the available scientific evidence significantly strengthens the link between long- and short-term exposure to PM
2.5and mortality, while providing 
indications that the magnitude of the PM
2.5-mortality association with long- 
term exposures may be larger than 
previously estimated.610 611 The 
strongest evidence comes from recent studies investigating long-term exposure to PM
2.5and cardiovascular-related 
mortality. The evidence supporting a causal relationship between long-term PM
2.5exposure and mortality also 
includes consideration of studies that demonstrated an improvement in community health following reductions in ambient fine particles. 
The 2009 PM ISA examined the 
association between cardiovascular effects and long-term PM
2.5exposures in 
multi-city epidemiological studies conducted in the U.S. and Europe. These studies have provided new evidence linking long-term exposure to PM
2.5with an array of cardiovascular 
effects such as heart attacks, congestive heart failure, stroke, and mortality. This evidence is coherent with epidemiological studies of effects associated with short-term exposure to PM
2.5that have observed associations 
with a continuum of effects ranging from subtle changes in indicators of cardiovascular health to serious clinical events, such as increased hospitalizations and emergency department visits due to cardiovascular disease and cardiovascular mortality.
612 
As detailed in the 2009 PM ISA, 
extended analyses of seminal epidemiological studies, as well as more recent epidemiological studies conducted in the U.S. and abroad, provide strong evidence of respiratory- related morbidity effects associated with long-term PM
2.5exposure. The strongest 
evidence for respiratory-related effects is from studies that evaluated 
decrements in lung function growth (in children), increased respiratory symptoms, and asthma development. The strongest evidence from short-term PM
2.5exposure studies has been 
observed for increased respiratory- related emergency department visits and hospital admissions for chronic obstructive pulmonary disease (COPD) and respiratory infections.
613 
The body of scientific evidence 
detailed in the 2009 PM ISA is still limited with respect to associations between long-term PM
2.5exposures and 
developmental and reproductive effects as well as cancer, mutagenic, and genotoxic effects. The strongest evidence for an association between PM
2.5and developmental and 
reproductive effects comes from epidemiological studies of low birth weight and infant mortality, especially due to respiratory causes during the post-neonatal period ( i.e., 1 month to 12 
months of age).
614With regard to cancer 
effects, ‘‘[m]ultiple epidemiologic studies have shown a consistent positive association between PM
2.5and 
lung cancer mortality, but studies have generally not reported associations between PM
2.5and lung cancer 
incidence.’’615 
In addition to evaluating the health 
effects attributed to short- and long-term exposure to PM
2.5, the 2009 PM ISA also 
evaluated whether specific components or sources of PM
2.5are more strongly 
associated with specific health effects. The 2009 PM ISA concluded that ‘‘many [components] of PM can be linked with differing health effects, and the evidence is not yet sufficient to allow differentiation of those [components] or 
sources that are more closely related to specific health outcomes.’’
616 
For PM 10–2.5 , the 2009 PM ISA 
concluded that available evidence was ‘‘suggestive of a causal relationship’’ between short-term exposures to PM
10–2.5 and cardiovascular effects (e.g., 
hospital admissions and Emergency Department (ED) visits, changes in 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00352 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243337 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
617U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. Section 2.3.4 and Table 2–6. 
61878 FR 3167–3168 (Jan. 15, 2013). 
61977 FR 38947–38951 (June 29, 2012). 
620U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. Section 2.3.5 and Table 2–6. 
62178 FR 3121 (Jan. 15, 2013). 
622U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. Chapter 8 and Chapter 2. 
62377 FR 38890 (June 29, 2012). 
62478 FR 3104 (Jan. 15, 2013). 
625U.S. EPA. (2011). Policy Assessment for the 
Review of the PM NAAQS. U.S. Environmental Protection Agency, Washington, DC, EPA/452/R– 11–003. Section 2.2.1. 626U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. Chapter 8 and Chapter 2 (Section 2.4.1). 
627Human exposure to ozone varies over time 
due to changes in ambient ozone concentration and because people move between locations which have notable different ozone concentrations. Also, the amount of ozone delivered to the lung is not only influenced by the ambient concentrations but also by the individuals breathing route and rate. 
628U.S. EPA. Integrated Science Assessment of 
Ozone and Related Photochemical Oxidants (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–10/076F, 2013. The ISA is available at http://cfpub.epa.gov/ncea/isa/ recordisplay.cfm?deid=247492#Download . 629The ISA evaluates evidence and draws 
conclusions on the causal nature of relationship between relevant pollutant exposures and health effects, assigning one of five ‘‘weight of evidence’’ determinations: Causal relationship, likely to be a causal relationship, suggestive of, but not sufficient to infer, a causal relationship, inadequate to infer a causal relationship, and not likely to be a causal relationship. For more information on these levels of evidence, please refer to Table II in the Preamble of the ISA. cardiovascular function), respiratory 
effects (e.g., ED visits and hospital 
admissions, increase in markers of pulmonary inflammation), and premature mortality. The scientific evidence was ‘‘inadequate to infer a causal relationship’’ between long-term exposure to PM
10–2.5 and various health 
effects.617 618 619  
For UFPs, the 2009 PM ISA 
concluded that the evidence was ‘‘suggestive of a causal relationship’’ between short-term exposures and cardiovascular effects, including changes in heart rhythm and vasomotor function (the ability of blood vessels to expand and contract). It also concluded that there was evidence ‘‘suggestive of a causal relationship’’ between short-term exposure to UFPs and respiratory effects, including lung function and pulmonary inflammation, with limited and inconsistent evidence for increases in ED visits and hospital admissions. Scientific evidence was ‘‘inadequate to infer a causal relationship’’ between short-term exposure to UFPs and additional health effects including premature mortality as well as long-term exposure to UFPs and all health outcomes evaluated.
620 621  
The 2009 PM ISA conducted an 
evaluation of specific groups within the general population potentially at increased risk for experiencing adverse health effects related to PM exposures.
622 623 624 625 The evidence 
detailed in the 2009 PM ISA expands our understanding of previously identified at-risk populations and lifestages (i.e., children, older adults, 
and individuals with pre-existing heart and lung disease) and supports the identification of additional at-risk populations (e.g., persons with lower 
socioeconomic status, genetic differences). Additionally, there is emerging, though still limited, evidence for additional potentially at-risk populations and lifestages, such as those with diabetes, people who are obese, pregnant women, and the developing fetus.
626 
2. Ozone 
(a) Background 
Ground-level ozone pollution is 
typically formed through reactions 
involving VOC and NO Xin the lower 
atmosphere in the presence of sunlight. These pollutants, often referred to as ozone precursors, are emitted by many types of sources, such as highway and nonroad motor vehicles and engines, power plants, chemical plants, refineries, makers of consumer and commercial products, industrial facilities, and smaller area sources. 
The science of ozone formation, 
transport, and accumulation is complex. Ground-level ozone is produced and destroyed in a cyclical set of chemical reactions, many of which are sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain high for several days and the air is relatively stagnant, ozone and its precursors can build up and result in more ozone than typically occurs on a single high-temperature day. Ozone and its precursors can be transported hundreds of miles downwind from precursor emissions, resulting in elevated ozone levels even in areas with low local VOC or NO
Xemissions. 
(b) Health Effects of Ozone 
This section provides a summary of 
the health effects associated with exposure to ambient concentrations of ozone.
627The information in this 
section is based on the information and conclusions in the February 2013 Integrated Science Assessment for Ozone (Ozone ISA), which formed the basis for EPA’s revision to the primary and secondary standards in 2015.
628 
The Ozone ISA concludes that human exposures to ambient concentrations of ozone are associated with a number of adverse health effects and characterizes the weight of evidence for these health effects.
629The discussion below 
highlights the Ozone ISA’s conclusions pertaining to health effects associated with both short-term and long-term periods of exposure to ozone. 
For short-term exposure to ozone, the 
Ozone ISA concludes that respiratory effects, including lung function decrements, pulmonary inflammation, exacerbation of asthma, respiratory- related hospital admissions, and mortality, are causally associated with ozone exposure. It also concludes that cardiovascular effects, including decreased cardiac function and increased vascular disease, and total mortality are likely to be causally associated with short-term exposure to ozone, and that evidence is suggestive of a causal relationship between central nervous system effects and short-term exposure to ozone. 
For long-term exposure to ozone, the 
Ozone ISA concludes that respiratory effects, including new onset asthma, pulmonary inflammation and injury, are likely to be causally related with ozone exposure. The Ozone ISA characterizes the evidence as suggestive of a causal relationship for associations between long-term ozone exposure and cardiovascular effects, reproductive and developmental effects, central nervous system effects and total mortality. The evidence is inadequate to infer a causal relationship between chronic ozone exposure and increased risk of lung cancer. 
Finally, inter-individual variation in 
human responses to ozone exposure can result in some groups being at increased risk for detrimental effects in response to exposure. In addition, some groups are at increased risk of exposure due to their activities, such as outdoor workers or children. The Ozone ISA identified several groups that are at increased risk for ozone-related health effects. These groups are people with asthma, children and older adults, individuals with reduced intake of certain nutrients ( i.e., 
Vitamins C and E), outdoor workers, and individuals having certain genetic variants related to oxidative metabolism 
or inflammation. Ozone exposure during childhood can have lasting effects through adulthood. Such effects include altered function of the 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00353 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243338 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
630U.S. EPA. Integrated Science Assessment for 
Oxides of Nitrogen—Health Criteria (2016 Final 
Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–15/068, 2016. 631U.S. EPA. (2008). Integrated Science 
Assessment (ISA) for Sulfur Oxides—Health Criteria (Final Report). EPA/600/R–08/047F. Washington, DC: U.S. Environmental Protection Agency. 
632U.S. EPA, (2010). Integrated Science 
Assessment for Carbon Monoxide (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–09/019F, 2010. Available at http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=218686. See Section 2.1. 
633U.S. EPA, (2010). Integrated Science 
Assessment for Carbon Monoxide (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–09/019F, 2010. Available at http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=218686. 
634Personal exposure includes contributions from 
many sources and in many different environments. Total personal exposure to CO includes both respiratory and immune systems. 
Children absorb higher doses (normalized to lung surface area) of ambient ozone, compared to adults, due to their increased time spent outdoors, higher ventilation rates relative to body size, and a tendency to breathe a greater fraction of air through the mouth. Children also have a higher asthma prevalence compared to adults. 
3. Nitrogen Oxides 
(a) Background 
Oxides of nitrogen (NO
X) refers to 
nitric oxide and nitrogen dioxide (NO 2). 
For the NO XNAAQS, NO 2is the 
indicator. Most NO 2is formed in the air 
through the oxidation of nitric oxide 
(NO) emitted when fuel is burned at a high temperature. NO
Xis also a major 
contributor to secondary PM 2.5 
formation. NO Xand VOC are the two 
major precursors of ozone. 
(b) Health Effects of Nitrogen Oxides 
The most recent review of the health 
effects of oxides of nitrogen completed 
by EPA can be found in the 2016 Integrated Science Assessment for Oxides of Nitrogen—Health Criteria (Oxides of Nitrogen ISA).
630The 
primary source of NO 2is motor vehicle 
emissions, and ambient NO 2 
concentrations tend to be highly correlated with other traffic-related pollutants. Thus, a key issue in characterizing the causality of NO
2- 
health effect relationships was evaluating the extent to which studies supported an effect of NO
2that is 
independent of other traffic-related pollutants. EPA concluded that the findings for asthma exacerbation integrated from epidemiologic and controlled human exposure studies provided evidence that is sufficient to infer a causal relationship between respiratory effects and short-term NO
2 
exposure. The strongest evidence supporting an independent effect of NO
2 
exposure comes from controlled human exposure studies demonstrating increased airway responsiveness in individuals with asthma following ambient-relevant NO
2exposures. The 
coherence of this evidence with epidemiologic findings for asthma hospital admissions and ED visits as well as lung function decrements and increased pulmonary inflammation in children with asthma describe a plausible pathway by which NO
2 
exposure can cause an asthma exacerbation. The 2016 ISA for Oxides of Nitrogen also concluded that there is likely to be a causal relationship between long-term NO
2exposure and 
respiratory effects. This conclusion is based on new epidemiologic evidence for associations of NO
2with asthma 
development in children combined with biological plausibility from experimental studies. 
In evaluating a broader range of health 
effects, the 2016 ISA for Oxides of Nitrogen concluded evidence is ‘‘suggestive of, but not sufficient to infer, a causal relationship’’ between short-term NO
2exposure and 
cardiovascular effects and mortality and between long-term NO
2exposure and 
cardiovascular effects and diabetes, birth outcomes, and cancer. In addition, the scientific evidence is inadequate (insufficient consistency of epidemiologic and toxicological evidence) to infer a causal relationship for long-term NO
2exposure with 
fertility, reproduction, and pregnancy, as well as with postnatal development. A key uncertainty in understanding the relationship between these non- respiratory health effects and short- or long-term exposure to NO
2is 
copollutant confounding, particularly by other roadway pollutants. The available evidence for non-respiratory health effects does not adequately address whether NO
2has an 
independent effect or whether it primarily represents effects related to other or a mixture of traffic-related pollutants. 
The 2016 ISA for Oxides of Nitrogen 
concluded that people with asthma, children, and older adults are at increased risk for NO
2-related health 
effects. In these groups and lifestages, NO
2is consistently related to larger 
effects on outcomes related to asthma exacerbation, for which there is confidence in the relationship with NO
2 
exposure. 
4. Sulfur Oxides 
(a) Background 
Sulfur dioxide (SO 2), a member of the 
sulfur oxide (SO X) family of gases, is 
formed from burning fuels containing 
sulfur (e.g., coal or oil derived), 
extracting gasoline from oil, or extracting metals from ore. SO
2and its 
gas phase oxidation products can dissolve in water droplets and further oxidize to form sulfuric acid which reacts with ammonia to form sulfates, which are important components of ambient PM. 
(b) Health Effects of SO
2 
Information on the health effects of 
SO 2can be found in the 2008 Integrated Science Assessment for Sulfur Oxides— 
Health Criteria (SO XISA).631Short-term 
peaks (5–10 minutes) of SO 2have long 
been known to cause adverse respiratory health effects, particularly among individuals with asthma. In addition to those with asthma (both children and adults), potentially at-risk lifestages include all children and the elderly. During periods of elevated ventilation, asthmatics may experience symptomatic bronchoconstriction within minutes of exposure. Following an extensive evaluation of health evidence from epidemiologic and laboratory studies, EPA concluded that there is a causal relationship between respiratory health effects and short-term exposure to SO
2. 
Separately, based on an evaluation of 
the epidemiologic evidence of associations between short-term exposure to SO
2and mortality, EPA 
concluded that the overall evidence is suggestive of a causal relationship between short-term exposure to SO
2and 
mortality. 
5. Carbon Monoxide 
(a) Background 
Carbon monoxide is a colorless, 
odorless gas emitted from combustion 
processes. Nationally, particularly in urban areas, the majority of CO emissions to ambient air come from mobile sources.
632 
(b) Health Effects of Carbon Monoxide 
Information on the health effects of 
CO can be found in the January 2010 Integrated Science Assessment for Carbon Monoxide (CO ISA) associated with the 2010 evaluation of the NAAQS.
633The CO ISA presents 
conclusions regarding the presence of causal relationships between CO exposure and categories of adverse health effects. This section provides a summary of the health effects associated with exposure to ambient concentrations of CO, along with the ISA conclusions.
634 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00354 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243339 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
ambient and nonambient components; both 
components may contribute to adverse health effects. 635U.S. EPA. (March 2005). Guidelines for 
Carcinogen Risk Assessment EPA/630/P–03/001F, 
https://www.epa.gov/risk/guidelines-carcinogen- risk-assessment (Last accessed July 2018). 
636U.S. EPA (2002). Health Assessment 
Document for Diesel Engine Exhaust. EPA/600/8– 90/057F Office of Research and Development, 
Washington, DC. Retrieved on March 17, 2009 from http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060 (last accessed July 2018). pp. 1–1 1–2. Controlled human exposure studies of 
subjects with coronary artery disease 
show a decrease in the time to onset of exercise-induced angina (chest pain) and electrocardiogram changes following CO exposure. In addition, epidemiologic studies observed associations between short-term CO exposure and cardiovascular morbidity, particularly increased emergency room visits and hospital admissions for coronary heart disease (including 
ischemic heart disease, myocardial infarction, and angina). Some epidemiologic evidence is also available for increased hospital admissions and emergency room visits for congestive heart failure and cardiovascular disease as a whole. The CO ISA concludes that a causal relationship is likely to exist between short-term exposures to CO and 
cardiovascular morbidity. It also 
concludes that available data are 
inadequate to conclude that a causal relationship exists between long-term exposures to CO and cardiovascular morbidity. 
Animal studies show various 
neurological effects with in-utero CO exposure. Controlled human exposure studies report central nervous system and behavioral effects following low- level CO exposures, although the findings have not been consistent across all studies. The CO ISA concludes the evidence is suggestive of a causal relationship with both short- and long- term exposure to CO and central nervous system effects. 
A number of studies cited in the CO 
ISA have evaluated the role of CO exposure in birth outcomes such as preterm birth or cardiac birth defects. There is limited epidemiologic evidence of a CO-induced effect on preterm births and birth defects, with weak evidence for a decrease in birth weight. Animal toxicological studies have found perinatal CO exposure to affect birth weight, as well as other developmental outcomes. The CO ISA concludes the evidence is suggestive of a causal relationship between long-term exposures to CO and developmental effects and birth outcomes. 
Epidemiologic studies provide 
evidence of associations between short- term CO concentrations and respiratory morbidity such as changes in pulmonary function, respiratory symptoms, and hospital admissions. A limited number of epidemiologic studies considered copollutants such as ozone, SO
2, and PM in two-pollutant 
models and found that CO risk estimates were generally robust, although this limited evidence makes it difficult to disentangle effects attributed to CO itself from those of the larger complex air pollution mixture. Controlled human exposure studies have not extensively evaluated the effect of CO on respiratory morbidity. Animal studies at levels of 50–100 ppm CO show preliminary evidence of altered pulmonary vascular remodeling and oxidative injury. The CO ISA concludes that the evidence is suggestive of a causal relationship between short-term CO exposure and respiratory morbidity, and inadequate to conclude that a causal relationship exists between long-term exposure and respiratory morbidity. 
Finally, the CO ISA concludes that 
the epidemiologic evidence is suggestive of a causal relationship between short-term concentrations of CO and mortality. Epidemiologic evidence suggests an association exists between short-term exposure to CO and mortality, but limited evidence is available to evaluate cause-specific mortality outcomes associated with CO exposure. In addition, the attenuation of CO risk estimates which was often observed in copollutant models contributes to the uncertainty as to whether CO is acting alone or as an indicator for other combustion-related pollutants. The CO ISA also concludes that there is not likely to be a causal relationship between relevant long-term exposures to CO and mortality. 
6. Diesel Exhaust 
(a) Background 
Diesel exhaust consists of a complex 
mixture composed of particulate matter, 
carbon dioxide, oxygen, nitrogen, water vapor, carbon monoxide, nitrogen compounds, sulfur compounds and numerous low-molecular-weight hydrocarbons. A number of these gaseous hydrocarbon components are individually known to be toxic, including aldehydes, benzene and 1,3- butadiene. The diesel particulate matter present in diesel exhaust consists mostly of fine particles (<2.5 mm), of 
which a significant fraction is ultrafine particles (< 0.1 mm). These particles have a large surface area which makes them an excellent medium for adsorbing organics, and their small size makes them highly respirable. Many of the organic compounds present in the gases and on the particles, such as polycyclic organic matter, are individually known to have mutagenic and carcinogenic properties. 
Diesel exhaust varies significantly in 
chemical composition and particle sizes between different engine types (heavy- duty, light-duty), engine operating 
conditions (idle, acceleration, deceleration), and fuel formulations (high/low sulfur fuel). Also, there are emissions differences between on-road and nonroad engines because the nonroad engines are generally of older technology. After being emitted in the engine exhaust, diesel exhaust undergoes dilution as well as chemical and physical changes in the atmosphere. The lifetime for some of the compounds present in diesel exhaust ranges from hours to days. 
(b) Health Effects of Diesel Exhaust 
In EPA’s 2002 Diesel Health 
Assessment Document (Diesel HAD), 
exposure to diesel exhaust was 
classified as likely to be carcinogenic to humans by inhalation from environmental exposures, in accordance with the revised draft 1996/1999 EPA cancer guidelines.
635 636 A number of 
other agencies (National Institute for Occupational Safety and Health, the International Agency for Research on Cancer, the World Health Organization, California EPA, and the U.S. Department of Health and Human Services) made similar hazard classifications prior to 2002. EPA also concluded in the 2002 Diesel HAD that it was not possible to calculate a cancer unit risk for diesel exhaust due to limitations in the exposure data for the occupational groups or the absence of a dose-response relationship. 
In the absence of a cancer unit risk, 
the Diesel HAD sought to provide additional insight into the significance of the diesel exhaust cancer hazard by estimating possible ranges of risk that might be present in the population. An exploratory analysis was used to characterize a range of possible lung cancer risk. The outcome was that environmental risks of cancer from long- term diesel exhaust exposures could plausibly range from as low as 10–5 to as high as 10–3. Because of uncertainties, the analysis acknowledged that the risks could be lower than 10–5, and a zero risk from diesel exhaust exposure could not be ruled out. 
Non-cancer health effects of acute and 
chronic exposure to diesel exhaust emissions are also of concern to EPA. EPA derived a diesel exhaust reference 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00355 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243340 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
637Garshick, E., Laden, F., Hart, J.E., Davis, M.E., 
Eisen, E.A., & Smith T.J. 2012. Lung cancer and 
elemental carbon exposure in trucking industry workers. Environmental Health Perspectives. 
120(9): 1301–1306. 
638Silverman, D.T., Samanic, C.M., Lubin, J.H., 
Blair, A.E., Stewart, P.A., Vermeulen, R., & Attfield, M.D. (2012). The diesel exhaust in miners study: a nested case-control study of lung cancer and diesel exhaust. Journal of the National Cancer Institute. 
639Olsson, A.C., et al. ‘‘Exposure to diesel motor 
exhaust and lung cancer risk in a pooled analysis from case-control studies in Europe and Canada.’’ American Journal of Respiratory and Critical Care Medicine 183(7). (2011): 941–948. 
640IARC [International Agency for Research on 
Cancer]. (2013). Diesel and gasoline engine exhausts and some nitroarenes. IARC Monographs Volume 105. [Online at http://monographs.iarc.fr/ENG/ Monographs/vol105/index.php]. 641U.S. EPA. (2015) Summary of Results for the 
2011 National-Scale Assessment. http://
www3.epa.gov/sites/production/files/2015-12/ documents/2011-nata-summary-results.pdf. 
642U.S. EPA (2015) 2011 National Air Toxics 
Assessment. http://www3.epa.gov/national-air- 
toxics-assessment/2011-national-air-toxics- assessment. 
643U.S. EPA. (2000). Integrated Risk Information 
System File for Benzene. This material is available electronically at: https://www.epa.gov/iris (Last 
accessed July 2018) 
644International Agency for Research on Cancer, 
IARC monographs on the evaluation of carcinogenic risk of chemicals to humans, Volume 29, some industrial chemicals and dyestuffs, International Agency for Research on Cancer, World Health Organization, Lyon, France 1982. 
645Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; 
Henry, V.A. (1992). Synergistic action of the benzene metabolite hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colony-stimulating factor in vitro, Proc. Natl. Acad. Sci. 89:3691–3695. 
646A unit risk estimate is defined as the increase 
in the lifetime risk of an individual who is exposed for a lifetime to 1 mg/m3 benzene in air. 
647U.S. EPA. (2000). Integrated Risk Information 
System File for Benzene. This material is available electronically at: http://www3.epa.gov/iris/subst/ 
0276.htm. 
648International Agency for Research on Cancer 
(IARC). (1987). Monographs on the evaluation of carcinogenic risk of chemicals to humans, Volume concentration (RfC) from consideration 
of four well-conducted chronic rat inhalation studies showing adverse pulmonary effects. The RfC is 5 mg/m3 
for diesel exhaust measured as diesel particulate matter. This RfC does not consider allergenic effects such as those associated with asthma or immunologic or the potential for cardiac effects. There was emerging evidence in 2002, discussed in the Diesel HAD, that exposure to diesel exhaust can exacerbate these effects, but the exposure-response data were lacking at that time to derive an RfC based on these then-emerging considerations. The EPA Diesel HAD states, ‘‘With [diesel particulate matter] being a ubiquitous component of ambient PM, there is an uncertainty about the adequacy of the existing [diesel exhaust] noncancer 
database to identify all of the pertinent 
[diesel exhaust]-caused noncancer health hazards.’’ The Diesel HAD also 
notes ‘‘that acute exposure to [diesel 
exhaust] has been associated with irritation of the eye, nose, and throat, respiratory symptoms (cough and phlegm), and neurophysiological symptoms such as headache, lightheadedness, nausea, vomiting, and numbness or tingling of the extremities.’’ The Diesel HAD noted that the cancer and noncancer hazard conclusions applied to the general use of diesel engines then on the market and as cleaner engines replace a substantial number of existing ones, the applicability of the conclusions would need to be reevaluated. 
It is important to note that the Diesel 
HAD also briefly summarizes health effects associated with ambient PM and discusses EPA’s then-annual PM
2.5 
NAAQS of 15 mg/m3. In 2012, EPA revised the annual PM
2.5NAAQS to 12 
mg/m3. There is a large and extensive body of human data showing a wide spectrum of adverse health effects associated with exposure to ambient PM, of which diesel exhaust is an important component. The PM
2.5 
NAAQS is designed to provide protection from the noncancer health effects and premature mortality attributed to exposure to PM
2.5. The 
contribution of diesel PM to total ambient PM varies in different regions of the country and also, within a region, from one area to another. The contribution can be high in near- roadway environments, for example, or in other locations where diesel engine use is concentrated. 
Since 2002, several new studies have 
been published which continue to report increased lung cancer risk with 
occupational exposure to diesel exhaust from older engines. Of particular note since 2011 are three new epidemiology 
studies which have examined lung cancer in occupational populations, for example, truck drivers, underground nonmetal miners and other diesel motor-related occupations. These studies reported increased risk of lung cancer with exposure to diesel exhaust with evidence of positive exposure- response relationships to varying degrees.
637 638 639 These newer studies 
(along with others that have appeared in the scientific literature) add to the evidence EPA evaluated in the 2002 Diesel HAD and further reinforces the concern that diesel exhaust exposure likely poses a lung cancer hazard. The findings from these newer studies do not necessarily apply to newer technology diesel engines b the newer engines have large reductions in the emission constituents compared to older technology diesel engines. 
In light of the growing body of 
scientific literature evaluating the health effects of exposure to diesel exhaust, in June 2012 the World Health Organization’s International Agency for Research on Cancer (IARC), a recognized international authority on the carcinogenic potential of chemicals and other agents, evaluated the full range of cancer-related health effects data for diesel engine exhaust. IARC concluded that diesel exhaust should be regarded as ‘‘carcinogenic to humans.’’
640This designation was an 
update from its 1988 evaluation that 
considered the evidence to be indicative of a ‘‘probable human carcinogen.’’ 
7. Air Toxics 
(a) Background 
Light-duty vehicle emissions 
contribute to ambient levels of air toxics 
that are known or suspected human or animal carcinogens, or that have noncancer health effects. The population experiences an elevated risk of cancer and other noncancer health effects from exposure to the class of pollutants known collectively as ‘‘air 
toxics.’’
641These compounds include, 
but are not limited to, benzene, 1,3- butadiene, formaldehyde, acetaldehyde, acrolein, polycyclic organic matter, and naphthalene. These compounds were identified as national or regional risk drivers or contributors in the 2011 National-scale Air Toxics Assessment and have significant inventory contributions from mobile sources.
642 
(b) Benzene 
EPA’s Integrated Risk Information 
System (IRIS) database lists benzene as a known human carcinogen (causing leukemia) by all routes of exposure and concludes that exposure is associated with additional health effects, including genetic changes in both humans and animals and increased proliferation of bone marrow cells in mice.
643 644 645  
EPA states in its IRIS database that data indicate a causal relationship between benzene exposure and acute lymphocytic leukemia and suggest a relationship between benzene exposure and chronic non-lymphocytic leukemia and chronic lymphocytic leukemia. EPA’s IRIS documentation for benzene also lists a range of 2.2 x 10–6 to 7.8 x 10–6 per mg/m3 as the unit risk estimate (URE) for benzene.
646 647 The 
International Agency for Research on Cancer (IARC) has determined that benzene is a human carcinogen and the U.S. Department of Health and Human Services (DHHS) has characterized benzene as a known human carcinogen.
648 649  
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00356 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243341 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
29, Supplement 7, Some industrial chemicals and 
dyestuffs, World Health Organization, Lyon, France. 
649NTP. (2014). 13th Report on Carcinogens. 
Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. 
650Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; 
Cohen, B.; Melikian, A.; Eastmond, D.; Rappaport, S.; Li, H.; Rupa, D.; Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok, E.; Li, Y.; Mu, R.; Xu, B.; Zhang, X.; Li, K. (2003). HEI Report 115, Validation & Evaluation of Biomarkers in Workers Exposed to Benzene in China. 
651Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. 
Cohen, et al. (2002). Hematological changes among 
Chinese workers with a broad range of benzene exposures. American. Journal of Industrial 
Medicine. 42: 275–285. 
652Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et 
al. (2004). Hematotoxically in Workers Exposed to 
Low Levels of Benzene. Science 306: 1774–1776. 
653Turtletaub, K.W. and Mani, C. (2003). Benzene 
metabolism in rodents at doses relevant to human exposure from Urban Air. Research Reports Health Effect Inst. Report No.113. 
654U.S. EPA. (2002). Health Assessment of 1,3- 
Butadiene. Office of Research and Development, National Center for Environmental Assessment, Washington Office, Washington, DC. Report No. EPA600–P–98–001F. This document is available electronically at http://www3.epa.gov/iris/supdocs/ buta-sup.pdf. 
655U.S. EPA. (2002). ‘‘Full IRIS Summary for 1,3- 
butadiene (CASRN 106–99–0)’’ Environmental Protection Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental Assessment, Washington, DC http://www3.epa.gov/iris/subst/0139.htm . 656International Agency for Research on Cancer 
(IARC). (1999). Monographs on the evaluation of carcinogenic risk of chemicals to humans, Volume 71, Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide and Volume 97 (in preparation), World Health Organization, Lyon, France. 
657International Agency for Research on Cancer 
(IARC). (2008). Monographs on the evaluation of carcinogenic risk of chemicals to humans, 1,3- Butadiene, Ethylene Oxide and Vinyl Halides (Vinyl Fluoride, Vinyl Chloride and Vinyl Bromide) Volume 97, World Health Organization, Lyon, France. 
658NTP. (2014). 13th Report on Carcinogens. 
Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. 
659U.S. EPA. (2002). ‘‘Full IRIS Summary for 1,3- 
butadiene (CASRN 106–99–0)’’ Environmental Protection Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental Assessment, Washington, DC https://cfpub.epa.gov/ncea/iris2/chemical
Landing.cfm?substance _nmbr=139 (Last accessed 
July 10, 2018). 
660Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. 
(1996). Subchronic toxicity of 4-vinylcyclohexene in rats and mice by inhalation. Fundamental Applied Toxicology. 32:1–10. 
661EPA. Integrated Risk Information System. 
Formaldehyde (CASRN 50–00–0) https://cfpub.epa.gov/ncea/iris/iris_ documents/ 
documents/subst/0419_ summary.pdf (Last accessed 
July 2018). 662NTP. (2014). 13th Report on Carcinogens. 
Research Triangle Park, NC: U.S. Department of 
Health and Human Services, Public Health Service, National Toxicology Program. 
663IARC Monographs on the Evaluation of 
Carcinogenic Risks to Humans Volume 100F (2012): Formaldehyde. 
664Hauptmann, M., Lubin, J. H., Stewart, P. A., 
Hayes, R. B., & Blair, A. 2003. Mortality from lymphohematopoetic malignancies among workers in formaldehyde industries. Journal of the National Cancer Institute 95: 1615–1623. 
665Hauptmann, M., Lubin, J. H., Stewart, P. A., 
Hayes, R. B., & Blair, A. 2004. Mortality from solid cancers among workers in formaldehyde industries. American Journal of Epidemiology 159: 1117–1130. 
666Beane Freeman, L. E., Blair, A., Lubin, J. H., 
Stewart, P. A., Hayes, R. B., Hoover, R. N., & 
Hauptmann, M. 2009. Mortality from lymph hematopoietic malignancies among workers in formaldehyde industries: The National Cancer Institute cohort. Journal of the National Cancer Institute. 101: 751–761. 
667Pinkerton, L. E. 2004. Mortality among a 
cohort of garment workers exposed to formaldehyde: an update. Occupational Environmental Medicine 61: 193–200. 
668Coggon, D., Harris, E. C. Poole, J., & Palmer, 
K. T. 2003. Extended follow-up of a cohort of British chemical workers exposed to formaldehyde. Journal of the National Cancer Institute. 95:1608– 1615. 
669Hauptmann, M., Stewart P. A., Lubin J. H., 
Beane Freeman, L. E., Hornung, R. W., Herrick, R. F., Hoover, R. N., Fraumeni, J. F., & Hayes, R. B. 2009. Mortality from lymph hematopoietic malignancies and brain cancer among embalmers exposed to formaldehyde. Journal of the National Cancer Institute 101:1696–1708. A number of adverse noncancer 
health effects including blood disorders, 
such as pre-leukemia and aplastic anemia, have also been associated with long-term exposure to benzene. The most sensitive noncancer effect observed in humans, based on current data, is the depression of the absolute lymphocyte count in blood. EPA’s inhalation reference concentration (RfC) for benzene is 30 mg/m3. The RfC is 
based on suppressed absolute lymphocyte counts seen in humans under occupational exposure conditions. In addition, recent work, including studies sponsored by the Health Effects Institute, provides evidence that biochemical responses are occurring at lower levels of benzene exposure than previously known.
650 651  
652 653 EPA’s IRIS program has not yet 
evaluated these new data. EPA does not currently have an acute reference concentration for benzene. The Agency for Toxic Substances and Disease Registry (ATSDR) Minimal Risk Level (MRL) for acute exposure to benzene is 29 mg/m3 for 1–14 days exposure. 
(c) 1,3-Butadiene 
EPA has characterized 1,3-butadiene 
as carcinogenic to humans by inhalation.
654 655 The IARC has 
determined that 1,3-butadiene is a human carcinogen and the U.S. DHHS has characterized 1,3-butadiene as a known human carcinogen.
656 657 658  
There are numerous studies consistently 
demonstrating that 1,3-butadiene is metabolized into genotoxic metabolites by experimental animals and humans. The specific mechanisms of 1,3- butadiene-induced carcinogenesis are unknown; however, the scientific evidence strongly suggests that the carcinogenic effects are mediated by genotoxic metabolites. Animal data suggest that females may be more sensitive than males for cancer effects associated with 1,3-butadiene exposure; there are insufficient data in humans from which to draw conclusions about sensitive subpopulations. The URE for 1,3-butadiene is 3 × 10
¥5per mg/m3.659 
1,3-butadiene also causes a variety of reproductive and developmental effects in mice; no human data on these effects are available. The most sensitive effect was ovarian atrophy observed in a lifetime bioassay of female mice.
660 
Based on this critical effect and the benchmark concentration methodology, 
an RfC for chronic health effects was calculated at 0.9 ppb (approximately 2 mg/m3). 
(d) Formaldehyde 
In 1991, EPA concluded that 
formaldehyde is a carcinogen based on 
nasal tumors in animal bioassays.
661An 
Inhalation URE for cancer and a Reference Dose for oral noncancer effects were developed by the agency and posted on the IRIS database. Since that time, the National Toxicology Program (NTP) and International 
Agency for Research on Cancer (IARC) have concluded that formaldehyde is a known human carcinogen.
662 663  
The conclusions by IARC and NTP 
reflect the results of epidemiologic 
research published since 1991 in combination with previous animal, human and mechanistic evidence. Research conducted by the National Cancer Institute reported an increased risk of nasopharyngeal cancer and specific lymph hematopoietic malignancies among workers exposed to formaldehyde.
664 665 666 A National 
Institute of Occupational Safety and 
Health study of garment workers also reported increased risk of death due to leukemia among workers exposed to formaldehyde.
667Extended follow-up of 
a cohort of British chemical workers did not report evidence of an increase in nasopharyngeal or lymph hematopoietic cancers, but a continuing statistically significant excess in lung cancers was reported.
668Finally, a study of 
embalmers reported formaldehyde exposures to be associated with an increased risk of myeloid leukemia but not brain cancer.
669 
Health effects of formaldehyde in 
addition to cancer were reviewed by the Agency for Toxics Substances and 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00357 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243342 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
670ATSDR. 1999. Toxicological Profile for 
Formaldehyde, U.S. Department of Health and 
Human Services (HHS), July 1999. 
671ATSDR. 2010. Addendum to the Toxicological 
Profile for Formaldehyde. U.S. Department of Health and Human Services (HHS), October 2010. 
672IPCS. 2002. Concise International Chemical 
Assessment Document 40. Formaldehyde. World Health Organization. 
673EPA (U.S. Environmental Protection Agency). 
2010. Toxicological Review of Formaldehyde (CAS No. 50–00–0)—Inhalation Assessment: In Support of Summary Information on the Integrated Risk Information System (IRIS). External Review Draft. EPA/635/R–10/002A. U.S. Environmental Protection Agency, Washington DC [online]. Available: http://cfpub.epa.gov/ncea/irs_ drats/ 
recordisplay.cfm?deid=223614. 
674NRC (National Research Council). 2011. 
Review of the Environmental Protection Agency’s Draft IRIS Assessment of Formaldehyde. Washington DC: National Academies Press. http:// 
books.nap.edu/openbook.php?record_ id=13142. 
675U.S. EPA (1991). Integrated Risk Information 
System File of Acetaldehyde. Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available electronically at http://www3.epa.gov/iris/ subst/0290.htm. 
676U.S. EPA (1991). Integrated Risk Information 
System File of Acetaldehyde. This material is available electronically at http://www3.epa.gov/iris/ 
subst/0290.htm. 
677NTP. (2014). 13th Report on Carcinogens. 
Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. 
678International Agency for Research on Cancer 
(IARC). (1999). Re-evaluation of some organic chemicals, hydrazine, and hydrogen peroxide. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemical to Humans, Vol 71. Lyon, France. 
679U.S. EPA (1991). Integrated Risk Information 
System File of Acetaldehyde. This material is available electronically at http://www3.epa.gov/iris/ subst/0290.htm. 
680U.S. EPA. (2003). Integrated Risk Information 
System File of Acrolein. Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available electronically at http://www3.epa.gov/iris/ subst/0364.htm. 
681Appleman, L.M., Woutersen, R. A., & Feron, 
V. J. (1982). Inhalation toxicity of acetaldehyde in rats. I. Acute and subacute studies. Toxicology. 23: 
293–297. 
682Myou, S., Fujimura, M., Nishi, K., Ohka, T., 
& Matsuda, T. (1993) Aerosolized acetaldehyde induces histamine-mediated bronchoconstriction in asthmatics. Am. Rev. Respir. Dis. 148(4 Pt 1): 940– 
943. 
683U.S. EPA. (2003). Integrated Risk Information 
System File of Acrolein. Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available at http://www3.epa.gov/iris/subst/ 0364.htm. 684International Agency for Research on Cancer 
(IARC). (1995). Monographs on the evaluation of carcinogenic risk of chemicals to humans, Volume 63. Dry cleaning, some chlorinated solvents and other industrial chemicals, World Health Organization, Lyon, France. 
685U.S. EPA. (2003). Integrated Risk Information 
System File of Acrolein. Office of Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available at http://www3.epa.gov/iris/subst/ 0364.htm. 
686U.S. EPA. (2003). Integrated Risk Information 
System File of Acrolein. Office of Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available at http://www3.epa.gov/iris/subst/ 0364.htm. 
687U.S. EPA. (2003) Toxicological review of 
acrolein in support of summary information on Integrated Risk Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R–03/003. p. 10. Available online at: http://www3.epa.gov/ncea/iris/toxreviews/ 0364tr.pdf. 
688U.S. EPA. (2003) Toxicological review of 
acrolein in support of summary information on Integrated Risk Information System (IRIS) National Center for Environmental Assessment, Washington, DC. EPA/635/R–03/003. Available online at: https:// 
cfpub.epa.gov/ncea/risk/recordisplay.cfm?
deid=51977 (Last accessed July 10 2018). 
689Morris, J. B., Symanowicz, P. T., Olsen, J. E., 
et al. (2003). Immediate sensory nerve-mediated respiratory responses to irritants in healthy and allergic airway-diseased mice. Journal of Applied Physiology. 94(4):1563–1571. Disease Registry in 1999,670 
supplemented in 2010,671and by the 
World Health Organization.672These 
organizations reviewed the scientific 
literature concerning health effects linked to formaldehyde exposure to evaluate hazards and dose response relationships and defined exposure concentrations for minimal risk levels (MRLs). The health endpoints reviewed included sensory irritation of eyes and respiratory tract, reduced pulmonary function, nasal histopathology, and immune system effects. In addition, research on reproductive and developmental effects and neurological effects were discussed along with several studies that suggest that formaldehyde may increase the risk of asthma, particularly in the young. 
EPA released a draft Toxicological 
Review of Formaldehyde—Inhalation Assessment through the IRIS program for peer review by the National Research Council (NRC) and public comment in June 2010.
673The draft assessment 
reviewed more recent research from animal and human studies on cancer and other health effects. The NRC released their review report in April 2011.
674EPA is currently developing a 
revised draft assessment in response to this review. 
(e) Acetaldehyde 
Acetaldehyde is classified in EPA’s 
IRIS database as a probable human 
carcinogen, based on nasal tumors in rats, and is considered toxic by the inhalation, oral, and intravenous routes.
675The URE in IRIS for 
acetaldehyde is 2.2 × 106per mg/ 
m3.676Acetaldehyde is reasonably anticipated to be a human carcinogen by the U.S. DHHS in the 13th Report on Carcinogens and is classified as possibly carcinogenic to humans (Group 2B) by the IARC.
677 678 Acetaldehyde is 
currently listed on the IRIS Program Multi-Year Agenda for reassessment within the next few years. 
The primary noncancer effects of 
exposure to acetaldehyde vapors include irritation of the eyes, skin, and respiratory tract.
679In short-term (four 
week) rat studies, degeneration of olfactory epithelium was observed at various concentration levels of acetaldehyde exposure.
680 681 Data from 
these studies were used by EPA to develop an inhalation reference concentration of 9 mg/m
3. Some 
asthmatics have been shown to be a 
sensitive subpopulation to decrements in functional expiratory volume (FEV1 test) and bronchoconstriction upon acetaldehyde inhalation.
682 
(f) Acrolein 
EPA most recently evaluated the 
toxicological and health effects literature related to acrolein in 2003 and concluded that the human carcinogenic potential of acrolein could not be determined because the available data were inadequate. No information was available on the carcinogenic effects of acrolein in humans and the animal data provided inadequate evidence of carcinogenicity.
683The IARC 
determined in 1995 that acrolein was not classifiable as to its carcinogenicity in humans.
684 
Lesions to the lungs and upper 
respiratory tract of rats, rabbits, and hamsters have been observed after subchronic exposure to acrolein.
685The 
agency has developed an RfC for acrolein of 0.02 mg/m
3and an RfD of 0.5 
mg/kg-day.686 
Acrolein is extremely acrid and 
irritating to humans when inhaled, with acute exposure resulting in upper respiratory tract irritation, mucus hypersecretion and congestion. The intense irritancy of this carbonyl has been demonstrated during controlled tests in human subjects, who suffer intolerable eye and nasal mucosal sensory reactions within minutes of exposure.
687These data and additional 
studies regarding acute effects of human exposure to acrolein are summarized in EPA’s 2003 Toxicological Review of Acrolein.
688Studies in humans indicate 
that levels as low as 0.09 ppm (0.21 mg/ m3) for five minutes may elicit subjective complaints of eye irritation with increasing concentrations leading to more extensive eye, nose and respiratory symptoms. Acute exposures in animal studies report bronchial hyper-responsiveness. Based on animal data (more pronounced respiratory irritancy in mice with allergic airway disease in comparison to non-diseased mice
689) and demonstration of similar 
effects in humans (e.g., reduction in 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00358 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243343 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
690U.S. EPA. (2009). Graphical Arrays of 
Chemical-Specific Health Effect Reference Values 
for Inhalation Exposures (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–09/061, 2009. http://cfpub.epa.gov/ ncea/cfm/recordisplay.cfm?deid=211003 (last 
accessed July 10 2018). 
691Agency for Toxic Substances and Disease 
Registry (ATSDR). (1995). Toxicological profile for Polycyclic Aromatic Hydrocarbons (PAHs). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. Available electronically at http://www.atsdr.cdc.gov/ ToxProfiles/TP.asp?id=122&tid=25. 
692U.S. EPA (2002). Health Assessment 
Document for Diesel Engine Exhaust. EPA/600/8– 90/057F Office of Research and Development, Washington DC. http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=29060 (last accessed July 10 
2018). 
693International Agency for Research on Cancer 
(IARC). (2012). Monographs on the Evaluation of the Carcinogenic Risk of Chemicals for Humans, Chemical Agents and Related Occupations. Vol. 100F. Lyon, France. 694U.S. EPA (1997). Integrated Risk Information 
System File of indeno (1,2,3-cd) pyrene. Research 
and Development, National Center for Environmental Assessment, Washington, DC. This material is available electronically at https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=2776 (Last accessed July 10 2018). 
695Perera, F. P., Rauh, V., Tsai, W. Y., et al. 
(2002). Effect of transplacental exposure to environmental pollutants on birth outcomes in a multiethnic population. Environmental Health Perspectives. 111: 201–205. 
696Perera, F. P., Rauh, V., Whyatt, R. M., Tsai, W. 
Y., Tang, D., Diaz, D., Hoepner, L., Barr, D., Tu, Y. H., Camann, D., & Kinney, P. (2006). Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons on neurodevelopment in the first 3 years of life among inner-city children. Environmental Health Perspectives. 114: 1287– 1292. 
697U. S. EPA. 1998. Toxicological Review of 
Naphthalene (Reassessment of the Inhalation Cancer Risk), Environmental Protection Agency, 
Integrated Risk Information System, Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available electronically at https://cfpub.epa.gov/ ncea/iris/iris_ documents/documents/toxreviews/ 
0436tr.pdf (last accessed July 10 2018). 
698U. S. EPA. 1998. Toxicological Review of 
Naphthalene (Reassessment of the Inhalation Cancer Risk), Environmental Protection Agency, Integrated Risk Information System, Research and Development, National Center for Environmental Assessment, Washington, DC. This material is available electronically at https://cfpub.epa.gov/ ncea/iris/iris_ documents/documents/toxreviews/ 
0436tr.pdf (last accessed July 10 2018) 699Oak Ridge Institute for Science and Education. 
(2004). External Peer Review for the IRIS Reassessment of the Inhalation Carcinogenicity of Naphthalene. August 2004. http://cfpub.epa.gov/ ncea/cfm/recordisplay.cfm?deid=84403 . 
700NTP. (2014). 13th Report on Carcinogens. U.S. 
Department of Health and Human Services, Public Health Service, National Toxicology Program. 
701International Agency for Research on Cancer 
(IARC). (2002). Monographs on the Evaluation of the Carcinogenic Risk of Chemicals for Humans. Vol. 82. Lyon, France. 
702U.S. EPA. (1998). Toxicological Review of 
Naphthalene. Environmental Protection Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental Assessment, Washington, DC https://cfpub.epa.gov/ncea/iris/iris _documents/ 
documents/toxreviews/0436tr.pdf (last accessed 
July 10 2018). 
703U.S. EPA Integrated Risk Information System 
(IRIS) database is available at: https://www.epa.gov/ iris (last accessed July 10 2018) respiratory rate), individuals with 
compromised respiratory function ( e.g., 
emphysema, asthma) are expected to be at increased risk of developing adverse responses to strong respiratory irritants such as acrolein. EPA does not currently 
have an acute reference concentration for acrolein. The available health effect reference values for acrolein have been summarized by EPA and include an ATSDR MRL for acute exposure to acrolein of 7 mg/m
3for 1–14 days’ 
exposure; and Reference Exposure Level (REL) values from the California Office of Environmental Health Hazard Assessment (OEHHA) for one-hour and 8-hour exposures of 2.5 mg/m
3and 0.7 
mg/m3, respectively.690 
(g) Polycyclic Organic Matter 
The term polycyclic organic matter 
(POM) defines a broad class of compounds that includes the polycyclic aromatic hydrocarbon compounds (PAHs). One of these compounds, naphthalene, is discussed separately below. POM compounds are formed primarily from combustion and are present in the atmosphere in gas and particulate form. Cancer is the major concern from exposure to POM. Epidemiologic studies have reported an increase in lung cancer in humans exposed to diesel exhaust, coke oven emissions, roofing tar emissions, and cigarette smoke; all of these mixtures contain POM compounds.
691 692 Animal 
studies have reported respiratory tract tumors from inhalation exposure to benzo[a]pyrene and alimentary tract and liver tumors from oral exposure to benzo[a]pyrene.
693In 1997 EPA 
classified seven PAHs (benzo[a]pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene) as Group B2, 
probable human carcinogens.
694Since 
that time, studies have found that maternal exposures to PAHs in a population of pregnant women were associated with several adverse birth outcomes, including low birth weight and reduced length at birth, as well as impaired cognitive development in preschool children (three years of age).
695 696 These and similar studies are 
being evaluated as a part of the ongoing IRIS reassessment of health effects associated with exposure to benzo[a]pyrene. 
(h) Naphthalene 
Naphthalene is found in small 
quantities in gasoline and diesel fuels. 
Naphthalene emissions have been measured in larger quantities in both gasoline and diesel exhaust compared with evaporative emissions from mobile sources, indicating it is primarily a product of combustion. Acute (short- term) exposure of humans to naphthalene by inhalation, ingestion, or dermal contact is associated with hemolytic anemia and damage to the liver and the nervous system.
697 
Chronic (long term) exposure of workers and rodents to naphthalene has been reported to cause cataracts and retinal damage.
698EPA released an external 
review draft of a reassessment of the inhalation carcinogenicity of naphthalene based on a number of recent animal carcinogenicity studies. 
The draft reassessment completed external peer review.
699Based on 
external peer review comments received, a revised draft assessment that considers all routes of exposure, as well as cancer and noncancer effects, is 
under development. The external review draft does not represent official agency opinion and was released solely for the purposes of external peer review and public comment. The National Toxicology Program listed naphthalene as ‘‘reasonably anticipated to be a human carcinogen’’ in 2004 on the basis of bioassays reporting clear evidence of carcinogenicity in rats and some evidence of carcinogenicity in mice.
700 
California EPA has released a new risk assessment for naphthalene, and the IARC has reevaluated naphthalene and re-classified it as Group 2B: Possibly carcinogenic to humans.
701 
Naphthalene also causes a number of 
chronic non-cancer effects in animals, including abnormal cell changes and growth in respiratory and nasal tissues. The current EPA IRIS assessment includes noncancer data on hyperplasia and metaplasia in nasal tissue that form the basis of the inhalation RfC of 3 mg/ 
m
3.702The ATSDR MRL for acute 
exposure to naphthalene is 0.6 mg/kg/ day. 
(i) Other Air Toxics 
In addition to the compounds 
described above, other compounds in 
gaseous hydrocarbon and PM emissions from motor vehicles will be affected by this action. Mobile source air toxic compounds that will potentially be impacted include ethylbenzene, propionaldehyde, toluene, and xylene. Information regarding the health effects of these compounds can be found in EPA’s IRIS database.
703 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00359 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243344 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
704Karner, A. A., Eisinger, D. S., & Niemeier, D. 
A. (2010). Near-roadway air quality: synthesizing 
the findings from real-world data. Environmental Science Technology. 44: 5334–5344. 
705Liu, W., Zhang, J., Kwon, J. et al. (2006). 
Concentrations and source characteristics of airborne carbonyl comlbs measured outside urban residences. Journal of the Air Waste Management 
Assocication 56: 1196–1204. 
706Cahill, T. M., Charles, M. J., & Seaman, V. Y. 
(2010). Development and application of a sensitive method to determine concentrations of acrolein and other carbonyls in ambient air. Health Effects Institute Research Report 149.Available at https:// 
www.healtheffects.org/publication/development- 
and-application-sensitive-method-determine- 
concentrations-acrolein-and-other (last accessed 
July 10 2018) 
707In the widely-used PubMed database of health 
publications, between January 1, 1990 and August 
18, 2011, 605 publications contained the keywords ‘‘traffic, pollution, epidemiology,’’ with approximately half the studies published after 2007. 
708Laden, F., Hart, J. E., Smith, T. J., Davis, M. 
E., & Garshick, E. (2007) Cause-specific mortality in the unionized U.S. trucking industry. Environmental Health Perspectives 115:1192–1196. 
709Peters, A., von Klot, S., Heier, M., 
Trentinaglia, I., Ho ¨rmann, A., Wichmann, H. E., & 
Lo¨wel, H. (2004) Exposure to traffic and the onset 
of myocardial infarction. New England Journal of Medicine. 351: 1721–1730. 
710Zanobetti, A., Stone, P. H., Spelzer, F. E., 
Schwartz, J. D., Coull, B. A., Suh, H. H., Nearling, B. D., Mittleman, M. A., Verrier, R. L., & Gold, D. R. (2009) T-wave alternans, air pollution and traffic in high-risk subjects. American Journal of Cardiology. 104: 665–670. 
711Dubowsky Adar, S., Adamkiewicz, G., Gold, 
D. R., Schwartz, J., Coull, B. A., & Suh, H. (2007) Ambient and microenvironmental particles and exhaled nitric oxide before and after a group bus trip. Environmental Health Perspectives. 115: 507– 
512. 
712Health Effects Institute Panel on the Health 
Effects of Traffic-Related Air Pollution. (2010). Traffic-related air pollution: A critical review of the literature on emissions, exposure, and health effects. HEI Special Report 17. Available at http:// 
www.healtheffects.org. 713Boothe, V. L. & Shendell, D. G. (2008). 
Potential health effects associated with residential 
proximity to freeways and primary roads: review of scientific literature, 1999–2006. Journal of Environmental Health. 70: 33–41. 
714Salam, M. T., Islam, T., & Gilliland, F. D. 
(2008). Recent evidence for adverse effects of residential proximity to traffic sources on asthma. Curr Opin Pulm Med 14: 3–8. 
715Sun, X., Zhang, S., & Ma, X. (2014) No 
association between traffic density and risk of childhood leukemia: a meta-analysis. Asia Pacific Journal of Cancer Prevention. 15: 5229–5232. 
716Raaschou-Nielsen, O. & Reynolds, P. (2006). 
Air pollution and childhood cancer: A review of the epidemiological literature. International Journal of Cancer. 118: 2920–9. 
717Boothe, V. L., Boehmer, T. K., Wendel, A. M., 
& Yip, F. Y. (2014) Residential traffic exposure and childhood leukemia: a systematic review and meta- analysis. American Journal of Preventative 
Medicine. 46: 413–422. (j) Exposure and Health Effects 
Associated With Traffic 
Locations in close proximity to major 
roadways generally have elevated concentrations of many air pollutants emitted from motor vehicles. Hundreds of such studies have been published in peer-reviewed journals, concluding that concentrations of CO, NO, NO
2, 
benzene, aldehydes, particulate matter, black carbon, and many other compounds are elevated in ambient air within approximately 300–600 meters (approximately 1,000–2,000 feet) of major roadways. Highest concentrations of most pollutants emitted directly by motor vehicles are found at locations within 50 meters (approximately 165 feet) of the edge of a roadway’s traffic lanes. 
A large-scale review of air quality 
measurements in the vicinity of major roadways between 1978 and 2008 concluded that the pollutants with the steepest concentration gradients in vicinities of roadways were CO, ultrafine particles, metals, elemental carbon (EC), NO, NO
X, and several 
VOCs.704These pollutants showed a 
large reduction in concentrations within 100 meters downwind of the roadway. Pollutants that showed more gradual reductions with distance from roadways included benzene, NO
2, PM 2.5, and 
PM 10. In the review article, results 
varied based on the method of statistical analysis used to determine the trend. 
For pollutants with relatively high 
background concentrations relative to near-road concentrations, detecting concentration gradients can be difficult. For example, many aldehydes have high background concentrations as a result of photochemical breakdown of precursors 
from many different organic compounds. This can make detection of gradients around roadways and other primary emission sources difficult. However, several studies have measured aldehydes in multiple weather conditions and found higher concentrations of many carbonyls downwind of roadways.
705 706 These findings suggest a substantial roadway 
source of these carbonyls. 
In the past 15 years, many studies 
have been published with results reporting that populations who live, work, or go to school near high-traffic roadways experience higher rates of numerous adverse health effects, compared to populations far away from major roads.
707In addition, numerous 
studies have found adverse health effects associated with spending time in traffic, such as commuting or walking along high-traffic roadways; however, it is difficult to fully control for confounding in such studies.
708 709 710 711 The health 
outcomes with the strongest evidence linking them with traffic-associated air pollutants are respiratory effects, particularly in asthmatic children, and cardiovascular effects. 
Numerous reviews of this body of 
health literature have been published as well. In 2010, an expert panel of the Health Effects Institute (HEI) published a review of hundreds of exposure, epidemiology, and toxicology studies.
712The panel rated how the 
evidence for each type of health outcome supported a conclusion of a causal association with traffic- associated air pollution as either ‘‘sufficient,’’ ‘‘suggestive but not sufficient,’’ or ‘‘inadequate and 
insufficient.’’ The panel categorized evidence of a causal association for exacerbation of childhood asthma as ‘‘sufficient.’’ The panel categorized evidence of a causal association for new onset asthma as between ‘‘sufficient’’ and ‘‘suggestive but not sufficient.’’ ‘‘Suggestive of a causal association’’ was how the panel categorized evidence linking traffic-associated air pollutants with exacerbation of adult respiratory symptoms and lung function decrement. It categorized as ‘‘inadequate and insufficient’’ evidence of a causal relationship between traffic-related air pollution and health care utilization for respiratory problems, new onset adult asthma, chronic obstructive pulmonary disease (COPD), nonasthmatic respiratory allergy, and cancer in adults 
and children. Other literature reviews have been published with conclusions generally similar to the HEI panel’s.
713 714 715 716 However, in 2014, 
researchers from the U.S. Centers for Disease Control and Prevention (CDC) published a systematic review and meta-analysis of studies evaluating the risk of childhood leukemia associated with traffic exposure and reported positive associations between ‘‘postnatal’’ proximity to traffic and leukemia risks, but no such association for ‘‘prenatal’’ exposures.
717 
Health outcomes with few 
publications suggest the possibility of other effects still lacking sufficient evidence to draw definitive conclusions. Among these outcomes with a small number of positive studies are neurological impacts (e.g., autism and 
reduced cognitive function) and reproductive outcomes (e.g., preterm 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00360 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243345 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
718Volk, H. E., Hertz-Picciotto, I., Delwiche, L., et 
al. (2011). Residential proximity to freeways and 
autism in the CHARGE study. Environmental 
Health Perspectives. 119: 873–877. 
719Franco-Suglia, S., Gryparis, A., Wright, R. O., 
et al. (2007). Association of black carbon with cognition among children in a prospective birth cohort study. American Journal of Epidemiology. doi: 10.1093/aje/kwm308. [Online at http://dx.doi.org]. 
720Power, M. C., Weisskopf, M. G., Alexeef, S. E., 
et al. (2011). Traffic-related air pollution and cognitive function in a cohort of older men. Environmental Health Perspectives. 2011: 682–687. 
721Wu, J., Wilhelm, M., Chung, J., et al. (2011). 
Comparing exposure assessment methods for traffic- related air pollution in and adverse pregnancy outcome study. Environmental Research. 111: 685– 6692. 
722Riediker, M. (2007). Cardiovascular effects of 
fine particulate matter components in highway patrol officers. Inhal Toxicol 19: 99–105. doi: 10.1080/08958370701495238 Available at http://dx.doi.org. 
723Alexeef, S. E., Coull, B. A., Gryparis, A., et al. 
(2011). Medium-term exposure to traffic-related air pollution and markers of inflammation and endothelial function. Environmental Health Perspectives. 119: 481–486. doi:10.1289/ 
ehp.1002560 Available at http://dx.doi.org. 
724Eckel, S. P., Berhane, K., Salam, M. T., et al. 
(2011). Traffic-related pollution exposure and exhaled nitric oxide in the Children’s Health Study. Environmental Health Perspectives. (IN PRESS). doi:10.1289/ehp.1103516. Available at http://dx.doi.org. 
725Zhang, J., McCreanor, J. E., Cullinan, P., et al. 
(2009). Health effects of real-world exposure diesel exhaust in persons with asthma. Res Rep Health Effects Inst 138. [Online at http://www.healtheffects.org]. 
726Adar, S. D., Klein, R., Klein, E. K., et al. 
(2010). Air pollution and the microvasculatory: a cross-sectional assessment of in vivo retinal images in the population-based Multi-Ethnic Study of Atherosclerosis. PLoS Med 7(11): E1000372. 
doi:10.1371/journal.pmed.1000372. Available at http://dx.doi.org. 
727Kan, H., Heiss, G., Rose, K. M., et al. (2008). 
Prospective analysis of traffic exposure as a risk factor for incident coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) study. Environmental Health Perspectives. 116: 1463– 1468. doi:10.1289/ehp.11290. Available at http://dx.doi.org. 
728McConnell, R., Islam, T., Shankardass, K., et 
al. (2010). Childhood incident asthma and traffic- 
related air pollution at home and school. Environmental Health Perspectives. 1021–1026. 729Islam, T., Urban, R., Gauderman, W. J., et al. 
(2011). Parental stress increases the detrimental effect of traffic exposure on children’s lung function. American Journal of Respiratory Critical 
Care Medicine. (In press). 
730Clougherty, J. E., Levy, J. I., Kubzansky, L. D., 
et al. (2007). Synergistic effects of traffic-related air pollution and exposure to violence on urban asthma etiology. Environmental Health Perspectives. 115: 
1140–1146. 
731Chen, E., Schrier, H. M., Strunk, R. C., et al. 
(2008). Chronic traffic-related air pollution and stress interact to predict biologic and clinical outcomes in asthma. Environmental Health Perspectives. 116: 970–5. 
732Rowangould, G. M. (2013) A census of the U.S. 
near-roadway population: public health and environmental justice considerations. Transportation Research Part D 25: 59–67. 
733Boehmer, T. K., Foster, S. L., Henry, J. R., 
Woghiren-Akinnifesi, E. L., & Yip, F. Y. (2013) Residential proximity to major highways—United States, 2010. Morbidity and Mortality Weekly Report 62 (3); 46–50. 
734http://www.cdc.gov/asthma/most_ recent_
data.htm. birth, low birth weight).718 719 720 721  
In addition to health outcomes, 
particularly cardiopulmonary effects, 
conclusions of numerous studies suggest mechanisms by which traffic- related air pollution affects health. Numerous studies indicate that near- roadway exposures may increase systemic inflammation, affecting organ systems, including blood vessels and lungs.
722 723 724 725 Long-term exposures 
in near-road environments have been associated with inflammation-associated conditions, such as atherosclerosis and asthma.
726 727 728  
Several studies suggest that some 
factors may increase susceptibility to the effects of traffic-associated air pollution. Several studies have found stronger respiratory associations in 
children experiencing chronic social stress, such as in violent neighborhoods or in homes with high family stress.
729 730 731  
The risks associated with residence, 
workplace, or schools near major roads are of potentially high public health significance due to the large population in such locations. According to the 2009 American Housing Survey, more than 22 million homes (17% of all U.S. housing units) were located within 300 feet of an airport, railroad, or highway with four or more lanes. This corresponds to a population of more than 50 million U.S. residents in close proximity to high-traffic roadways or other transportation sources. Based on 2010 Census data, a 2013 publication estimated that 19% of the U.S. population (more than 59 million people) lived within 500 meters of roads with at least 25,000 annual average daily traffic (AADT), while about 3.2% of the population lived within 100 meters (about 300 feet) of such roads.
732 
Another 2013 study estimated that 3.7% of the U.S. population (about 11.3 million people) lived within 150 meters (about 500 feet) of interstate highways or other freeways and expressways.
733 
On average, populations near major roads have higher fractions of minority residents and lower socioeconomic status. Furthermore, on average, Americans spend more than an hour traveling each day, bringing nearly all residents into a high-exposure microenvironment for part of the day. 
In light of these concerns, EPA has 
required through the NAAQS process 
that air quality monitors be placed near high-traffic roadways for determining concentrations of CO, NO
2, and PM 2.5 
(in addition to those existing monitors located in neighborhoods and other locations farther away from pollution sources). Near-roadway monitors for 
NO
2begin operation between 2014 and 
2017 in Core Based Statistical Areas (CBSAs) with population of at least 500,000. Monitors for CO and PM
2.5 
begin operation between 2015 and 2017. These monitors will further our understanding of exposure in these locations. 
EPA and DOT continue to research 
near-road air quality, including the types of pollutants found in high concentrations near major roads and 
health problems associated with the mixture of pollutants near roads. 
8. Environmental Justice 
Environmental justice (EJ) is a 
principle asserting that all people 
deserve fair treatment and meaningful involvement with respect to environmental laws, regulations, and policies. EPA seeks to provide the same degree of protection from environmental health hazards for all people. DOT shares this goal and is informed about the potential environmental impacts of its rulemakings through its NEPA process (see NHTSA’s DEIS). As referenced below, numerous studies have found that some environmental hazards are more prevalent in areas where non-white, Hispanic and people with low socioeconomic status (SES) represent a higher fraction of the population compared with the general population. In addition, compared to non-Hispanic whites, some subpopulations defined by race and ethnicity have been shown to have greater levels of some health conditions during some life stages. For example, in 2014, about 13% of Black, non-Hispanic and 24% of Puerto Rican children were estimated to currently have asthma, compared with eight percent of white, non-Hispanic children.
734 
As discussed in the DEIS, 
concentrations of many air pollutants are elevated near high-traffic roadways. If minority populations and low-income populations disproportionately live near such roads, then an issue of EJ may be present. We reviewed existing scholarly literature examining the potential for disproportionate exposure among people with low SES, and we conducted our own evaluation of two national datasets: The U.S. Census Bureau’s American Housing Survey for calendar year 2009 and the U.S. Department of Education’s database of school locations. 
Publications that address EJ issues 
generally report that populations living near major roadways (and other types of 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00361 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243346 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
735Marshall, J. D. (2008) Environmental 
inequality: air pollution exposures in California’s 
South Coast Air Basin. 
736Su, J. G., Larson, T., Gould, T., Cohen, M., & 
Buzzelli, M. (2010) Transboundary air pollution and environmental justice: Vancouver and Seattle compared. GeoJournal 57: 595–608. doi:10.1007/ 
s10708–009–9269–6 [Online at http://dx.doi.org]. 
737Chakraborty, J. & Zandbergen, P. A. (2007) 
Children at risk: measuring racial/ethnic disparities in potential exposure to air pollution at school and home. Journal of Epidemiol Community Health 61: 
1074–1079. doi: 10.1136/jech.2006.054130 [Online at http://dx.doi.org]. 
738Green, R. S., Smorodinsky, S., Kim, J. J., 
McLaughlin, R., & Ostro, B. (2003) Proximity of California public schools to busy roads. Environmental Health Perspectives. 112: 61–66. doi:10.1289/ehp.6566 [http://dx.doi.org]. 
739Wu, Y. & Batterman, S. A. (2006) Proximity of 
schools in Detroit, Michigan to automobile and truck traffic. Journal of Exposure Science & Environmental Epidemiology. doi:10.1038/ sj.jes.7500484 [Online at http://dx.doi.org]. 
740Su, J. G., Jerrett, M., de Nazelle, A., & Wolch, 
J. (2011) Does exposure to air pollution in urban parks have socioeconomic, racial, or ethnic gradients? Environmental Research. 111: 319–328. 
741Depro, B. & Timmins, C. (2008) Mobility and 
environmental equity: do housing choices determine exposure to air pollution? North Caroline State University Center for Environmental and Resource Economic Policy 
742Clougherty, J. E. & Kubzansky, L. D. (2009) A 
framework for examining social stress and susceptibility to air pollution in respiratory health. Environmental Health Perspectives. 117: 1351– 1358. Doi:10.1289/ehp.0900612 [Online at http://
dx.doi.org]. 
743Clougherty, J. E., Levy, J. I., Kubzansky, L. D., 
Ryan, P. B., Franco Suglia, S., Jacobson Canner, M., & Wright, R. J. (2007) Synergistic effects of traffic- related air pollution and exposure to violence on urban asthma etiology. Environmental Health Perspectives. 115: 1140–1146. doi:10.1289/ehp.9863 
[Online at http://dx.doi.org]. 
744Finkelstein, M. M., Jerrett, M., DeLuca, P., 
Finkelstein, N., Verma, D. K., Chapman, K., & Sears, M. R. (2003) Relation between income, air pollution and mortality: A cohort study. Canadian Medical Association Journal. 169: 397–402. 
745Shankardass, K., McConnell, R., Jerrett, M., 
Milam, J., Richardson, J., & Berhane, K. (2009) Parental stress increases the effect of traffic-related 
air pollution on childhood asthma incidence. Proc National Academy of Science. 106: 12406–12411. doi:10.1073/pnas.0812910106 [Online at http://dx.doi.org]. 
746Lewis, A. S., Sax, S. N., Wason, S. C. & 
Campleman, S. L (2011) Non-chemical stressors and cumulative risk assessment: an overview of current initiatives and potential air pollutant interactions. International Journal of Environmental Research in Public Health. 8: 2020–2073. Doi:10.3390/ ijerph8062020 [Online at http://dx.doi.org]. 
747Rosa, M. J., Jung, K. H., Perzanowski, M. S., 
Kelvin, E. A., Darling, K.W., Camann, D. E., Chillrud, S. N., Whyatt, R. M., Kinney, P. L., Perera, F. P., & Miller, R. L. (2010) Prenatal exposure to polycyclic aromatic hydrocarbons, environmental tobacco smoke and asthma. Respiratory Medicine. (In press). doi:10.1016/j.rmed.2010.11.022 [Online at http://dx.doi.org]. 
748This variable primarily represents roadway 
proximity. According to the Central Intelligence Agency’s World Factbook, in 2010, the United States had 6,506,204 km or roadways, 224,792 km of railways, and 15,079 airports. Highways thus represent the overwhelming majority of transportation facilities described by this factor in the AHS. 
749Bailey, C. (2011) Demographic and Social 
Patterns in Housing Units Near Large Highways and other Transportation Sources. Memorandum to docket. 750http://nces.ed.gov/ccd/. 
751Pedde, M. & Bailey, C. (2011) Identification of 
Schools within 200 Meters of U.S. Primary and 
Secondary Roads. Memorandum to the docket. 
752National Research Council, (1993). Protecting 
Visibility in National Parks and Wilderness Areas. National Academy of Sciences Committee on Haze in National Parks and Wilderness Areas. National Academy Press, Washington, DC. This book can be viewed on the National Academy Press website at http://www.nap.edu/books/0309048443/html/ . transportation infrastructure) tend to be 
composed of larger fractions of nonwhite residents. People living in neighborhoods near such sources of air pollution also tend to be lower in income than people living elsewhere. Numerous studies evaluating the demographics and socioeconomic status of populations or schools near roadways have found that they include a greater percentage of minority residents, as well as lower SES (indicated by variables such as median household income). 
Locations in these studies include Los Angeles, CA; Seattle, WA; Wayne County, MI; Orange County, FL; and California
735 736 737 738 739 740 Such 
disparities may be due to multiple factors.
741 
People with low SES often live in 
neighborhoods with multiple environmental stressors and higher rates of health risk factors, including reduced health insurance coverage rates, higher smoking and drug use rates, limited access to fresh food, visible neighborhood violence, and elevated rates of obesity and some diseases such as asthma, diabetes, and ischemic heart disease. Although questions remain, several studies find stronger associations between air pollution and health in locations with such chronic neighborhood stress, suggesting that populations in these areas may be more susceptible to the effects of air pollution.
742 743 744 745 Household-level stressors such as parental smoking and 
relationship stress also may increase susceptibility to the adverse effects of air pollution.
746 747  
Two national databases were analyzed 
that allowed evaluation of whether homes and schools were located near a major road and whether disparities in exposure may be occurring in these environments. The American Housing Survey (AHS) includes descriptive statistics of over 70,000 housing units across the nation. The study survey is conducted every two years by the U.S. Census Bureau. The second database we analyzed was the U.S. Department of Education’s Common Core of Data, which includes enrollment and location information for schools across the U.S. 
In analyzing the 2009 AHS, the focus 
was on whether or not a housing unit was located within 300 feet of ‘‘4-or- more lane highway, railroad, or airport.’’
748Whether there were 
differences between households in such locations compared with those in locations farther from these same transportation facilities was analyzed.
749Other variables, such as land use category, region of country, 
and housing type were included. 
In examining schools near major 
roadways, the Common Core of Data (CCD) from the U.S. Department of Education, which includes information on all public elementary and secondary schools and school districts nationwide, was examined.
750To determine school 
proximities to major roadways, a geographic information system (GIS) to map each school and roadways based on the U.S. Census’s TIGER roadway file was used.
751Non-white students were 
found to be overrepresented at schools within 200 meters of the largest roadways, and schools within 200 meters of the largest roadways also had higher than expected numbers of students eligible for free or reduced- price lunches. For example, Black students represent 22% of students at schools located within 200 meters of a primary road, whereas Black students represent 17% of students in all U.S. schools. Hispanic students represent 30% of students at schools located within 200 meters of a primary road, whereas Hispanic students represent 22% of students in all U.S. schools. 
Overall, there is substantial evidence 
that people who live or attend school near major roadways are more likely to be non-white, Hispanic ethnicity, and/ or low SES. The emission reductions from these proposed standards will likely result in widespread air quality improvements, but the impact on pollution levels in close proximity to roadways will be most direct. Thus, these proposed standards will likely help in mitigating the disparity in racial, ethnic, and economically based exposures. 
9. Environmental Effects of Non-GHG 
Pollutants 
(a) Visibility 
Visibility can be defined as the degree 
to which the atmosphere is transparent 
to visible light.
752Visibility impairment 
is caused by light scattering and absorption by suspended particles and gases. Visibility is important because it has direct significance to people’s enjoyment of daily activities in all parts of the country. Individuals value good visibility for the well-being it provides 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00362 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243347 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
753U.S. EPA. (2009). Integrated Science 
Assessment for Particulate Matter (Final Report). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F. 
754U.S. EPA. 2009 Final Report: Integrated 
Science Assessment for Particulate Matter. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, 2009. 
755See Section 169(a) of the Clean Air Act. 
75664 FR 35714 (July 1, 1999). 
75762 FR 38680–38681 (July 18, 1997). 
75878 FR 3226, January 15, 2013. 75973 FR 16486 (Mar. 27, 2008). 
76073 FR 16491 (Mar. 27, 2008). Only a small 
percentage of all the plant species growing within 
the U.S. (over 43,000 species have been catalogued in the USDA PLANTS database) have been studied with respect to ozone sensitivity. 
761The concentration at which ozone levels 
overwhelm a plant’s ability to detoxify or compensate for oxidant exposure varies. Thus, 
whether a plant is classified as sensitive or tolerant depends in part on the exposure levels being considered. Chapter 9, Section 9.3.4 of U.S. EPA, 2013 Integrated Science Assessment for Ozone and Related Photochemical Oxidants. Office of Research and Development/National Center for Environmental Assessment. U.S. Environmental Protection Agency. EPA 600/R–10/076F. 
76273 FR 16492 (Mar. 27, 2008). 
76373 FR 16493–16494 (Mar. 27, 2008). Ozone 
impacts could be occurring in areas where plant species sensitive to ozone have not yet been studied or identified. 76473 FR 16490–16497 (Mar. 27, 2008). 
765U.S. EPA. Integrated Science Assessment of 
Ozone and Related Photochemical Oxidants (Final 
Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–10/076F, 2013. The ISA is available at http://cfpub.epa.gov/ncea/isa/ recordisplay.cfm?deid=247492#Download . 
766The Ozone ISA evaluates the evidence 
associated with different ozone related health and welfare effects, assigning one of five ‘‘weight of evidence’’ determinations: Causal relationship, likely to be a causal relationship, suggestive of a causal relationship, inadequate to infer a causal relationship, and not likely to be a causal relationship. For more information on these levels of evidence, please refer to Table II of the ISA. them directly, where they live and 
work, and in places where they enjoy recreational opportunities. Visibility is also highly valued in significant natural areas, such as national parks and wilderness areas, and special emphasis is given to protecting visibility in these areas. For more information on visibility see the final 2009 PM ISA.
753 
EPA is working to address visibility 
impairment. Reductions in air pollution from implementation of various programs associated with the Clean Air Act Amendments of 1990 (CAAA) provisions have resulted in substantial improvements in visibility and will continue to do so in the future. Because trends in haze are closely associated with trends in particulate sulfate and nitrate due to the relationship between their concentration and light extinction, visibility trends have improved as emissions of SO
2and NO Xhave 
decreased over time due to air pollution regulations such as the Acid Rain Program.
754 
In the Clean Air Act Amendments of 
1977, Congress recognized visibility’s value to society by establishing a national goal to protect national parks and wilderness areas from visibility impairment caused by manmade pollution.
755In 1999, EPA finalized the 
regional haze program to protect the visibility in Mandatory Class I Federal areas.
756There are 156 national parks, 
forests and wilderness areas categorized as Mandatory Class I Federal areas.
757 
These areas are defined in CAA Section 162 as those national parks exceeding 6,000 acres, wilderness areas and memorial parks exceeding 5,000 acres, and all international parks which were in existence on August 7, 1977. 
EPA has also concluded that PM
2.5 
can cause adverse effects on visibility in other areas that are not targeted by the Regional Haze Rule, such as urban areas, depending on PM
2.5 
concentrations and other factors such as dry chemical composition and relative humidity (i.e., an indicator of the water 
composition of the particles).
758In 
December 2012, EPA revised the primary (health-based) PM
2.5standards 
in order to increase public health protection. As part of that same review, the EPA generally retained the 
secondary (welfare-based) PM
2.5 
standards, concluding that the target level of protection against PM-related visibility impairment would be achieved in areas meeting the existing secondary standards for PM
2.5. 
(b) Plant and Ecosystem Effects of Ozone 
The welfare effects of ozone can be 
observed across a variety of scales, i.e. 
subcellular, cellular, leaf, whole plant, population and ecosystem. Ozone can produce both acute and chronic injury in sensitive species depending on the concentration level and the duration of the exposure.
759In those sensitive 
species,760effects from repeated 
exposure to ozone throughout the growing season of the plant tend to accumulate, so that even low concentrations experienced for a longer duration have the potential to create chronic stress on vegetation.
761Ozone 
damage to sensitive species includes impaired photosynthesis and visible injury to leaves. The impairment of photosynthesis, the process by which the plant makes carbohydrates (its source of energy and food), can lead to reduced crop yields, timber production, and plant productivity and growth. Impaired photosynthesis can also lead to a reduction in root growth and carbohydrate storage below ground, resulting in other, more subtle plant and ecosystems impacts.
762These latter 
impacts include increased susceptibility of plants to insect attack, disease, harsh weather, interspecies competition and overall decreased plant vigor. The adverse effects of ozone on areas with sensitive species could potentially lead to species shifts and loss from the affected ecosystems,
763resulting in a 
loss or reduction in associated ecosystem goods and services. Additionally, visible ozone injury to leaves can result in a loss of aesthetic value in areas of special scenic 
significance like national parks and wilderness areas and reduced use of sensitive ornamentals in landscaping.
764 
The most recent Integrated Science 
Assessment (ISA) for Ozone presents more detailed information on how ozone affects vegetation and ecosystems.
765The ISA concludes that 
ambient concentrations of ozone are associated with a number of adverse welfare effects and characterizes the weight of evidence for different effects associated with ozone.
766The ISA 
concludes that visible foliar injury effects on some vegetation, reduced vegetation growth, reduced productivity in terrestrial ecosystems, reduced yield and quality of some agricultural crops, and alteration of below-ground biogeochemical cycles are causally associated with exposure to ozone. It also concludes that reduced carbon sequestration in terrestrial ecosystems, alteration of terrestrial ecosystem water cycling, and alteration of terrestrial community composition are likely to be causally associated with exposure to ozone. 
(c) Atmospheric Deposition 
Wet and dry deposition of ambient 
particulate matter delivers a complex 
mixture of metals (e.g., mercury, zinc, 
lead, nickel, aluminum, and cadmium), organic compounds (e.g., polycyclic 
organic matter, dioxins, and furans), and inorganic compounds (e.g., nitrate, 
sulfate) to terrestrial and aquatic ecosystems. The chemical form of the compounds deposited depends on a variety of factors including ambient conditions (e.g., temperature, humidity, 
oxidant levels) and the sources of the material. Chemical and physical transformations of the compounds occur in the atmosphere as well as the media onto which they deposit. These transformations in turn influence the fate, bioavailability and potential toxicity of these compounds. 
Adverse impacts to human health and 
the environment can occur when particulate matter is deposited to soils, 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00363 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243348 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
767U.S. EPA. Integrated Science Assessment for 
Particulate Matter (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R–08/139F, 2009. 
768U.S. EPA. (2000). Deposition of Air Pollutants 
to the Great Waters: Third Report to Congress. Office of Air Quality Planning and Standards. EPA– 453/R–00–0005. 
769NO Xand SO Xsecondary ISA U.S. EPA. 
Integrated Science Assessment (ISA) for Oxides of Nitrogen and Sulfur Ecological Criteria (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R–08/082F, 2008. 770U.S. Environmental Protection Agency (U.S. 
EPA). 2009. Integrated Science Assessment for Particulate Matter (Final Report). EPA–600–R–08– 139F. National Center for Environmental Assessment—RTP Division. December. Available on the internet at http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=216546. 
771Irving, P.M., e.d. 1991. Acid Deposition: State 
of Science and Technology, Volume III, Terrestrial, Materials, Health, and Visibility Effects, The U.S. National Acid Precipitation Assessment Program, Chapter 24, page 24–76. 
772U.S. EPA. (1991). Effects of organic chemicals 
in the atmosphere on terrestrial plants. EPA/600/3– 91/001. 
773Cape J. N., Leith, I. D., Binnie, J., Content, J., 
Donkin, M., Skewes, M., Price, D. N., Brown, A. R., & Sharpe, A. D. (2003). Effects of VOCs on herbaceous plants in an open-top chamber experiment. Environmental Pollution. 124:341–343. 774Cape, J. N., Leith, I. D., Binnie, J., Content, J., 
Donkin, M., Skewes, M., Price, D. N., Brown, A. R., & Sharpe, A. D. (2003). Effects of VOCs on herbaceous plants in an open-top chamber experiment. Environmental Pollution. 124:341–343. 
775Viskari E. L. (2000). Epicuticular wax of 
Norway spruce needles as indicator of traffic pollutant deposition. Water, Air, and Soil Pollution. 121:327–337. 
776Ugrekhelidze, D., Korte, F., & Kvesitadze, G. 
(1997). Uptake and transformation of benzene and toluene by plant leaves. Ecotox. Environ. Safety 37:24–29. 
777Kammerbauer H., Selinger, H, on Rommelt, R., 
Ziegler-Jons, A., Knoppik, D., & Hock, B. (1987). Toxic components of motor vehicle emissions for the spruce Picea abies. Environmental Pollution. 48:235–243. water, and biota.767Deposition of heavy 
metals or other toxics may lead to the 
human ingestion of contaminated fish, impairment of drinking water, damage to terrestrial, freshwater and marine ecosystem components, and limits to recreational uses. Atmospheric deposition has been identified as a key component of the environmental and human health hazard posed by several pollutants including mercury, dioxin and PCBs.
768 
The ecological effects of acidifying 
deposition and nutrient enrichment are detailed in the Integrated Science Assessment for Oxides of Nitrogen and Sulfur-Ecological Criteria.
769 
Atmospheric deposition of nitrogen and sulfur contributes to acidification, altering biogeochemistry and affecting animal and plant life in terrestrial and aquatic ecosystems across the United States. The sensitivity of terrestrial and aquatic ecosystems to acidification from nitrogen and sulfur deposition is predominantly governed by geology. Prolonged exposure to excess nitrogen and sulfur deposition in sensitive areas acidifies lakes, rivers, and soils. Increased acidity in surface waters creates inhospitable conditions for biota and affects the abundance and biodiversity of fishes, zooplankton, macroinvertebrates, and ecosystem function. Over time, acidifying deposition also removes essential nutrients from forest soils, depleting the capacity of soils to neutralize future acid loadings and negatively affecting forest sustainability. Major effects in forests include a decline in sensitive tree species, such as red spruce ( Picea 
rubens) and sugar maple (Acer saccharum). In addition to the role nitrogen deposition plays in acidification, nitrogen deposition also leads to nutrient enrichment and altered 
biogeochemical cycling. In aquatic systems increased nitrogen can alter species assemblages and cause eutrophication. In terrestrial systems nitrogen loading can lead to loss of nitrogen-sensitive lichen species, decreased biodiversity of grasslands, meadows and other sensitive habitats, and increased potential for invasive 
species. 
Building materials including metals, 
stones, cements, and paints undergo natural weathering processes from exposure to environmental elements (e.g., wind, moisture, temperature 
fluctuations, sunlight, etc.). Pollution can worsen and accelerate these effects. Deposition of PM is associated with both physical damage (materials damage effects) and impaired aesthetic qualities (soiling effects). Wet and dry deposition of PM can physically affect materials, adding to the effects of natural weathering processes, by potentially promoting or accelerating the corrosion of metals, by degrading paints and by deteriorating building materials such as stone, concrete and marble.
770The 
effects of PM are exacerbated by the presence of acidic gases and can be additive or synergistic due to the complex mixture of pollutants in the air and surface characteristics of the material. Acidic deposition has been shown to have an effect on materials including zinc/galvanized steel and other metal, carbonate stone (as monuments and building facings), and surface coatings (paints).
771The effects 
on historic buildings and outdoor works of art are of particular concern because of the uniqueness and irreplaceability of many of these objects. 
(d) Environmental Effects of Air Toxics 
Emissions from producing, 
transporting, and combusting fuel 
contribute to ambient levels of pollutants that contribute to adverse effects on vegetation. Volatile organic compounds, some of which are considered air toxics, have long been suspected to play a role in vegetation damage.
772In laboratory experiments, a 
wide range of tolerance to VOCs has been observed.
773Decreases in 
harvested seed pod weight have been reported for the more sensitive plants, and some studies have reported effects on seed germination, flowering and fruit 
ripening. Effects of individual VOCs or their role in conjunction with other stressors (e.g., acidification, drought, 
temperature extremes) have not been well studied. In a recent study of a mixture of VOCs including ethanol and toluene on herbaceous plants, significant effects on seed production, leaf water content, and photosynthetic efficiency were reported for some plant species.
774 
Research suggests an adverse impact 
of vehicle exhaust on plants, which has in some cases been attributed to aromatic compounds and in other cases to nitrogen oxides.
775 776 777  
F. Air Quality Impacts of Non-GHG Pollutants 
Changes in emissions of non-GHG 
pollutants due to these rules will impact air quality. Information on current air quality and the results of our air quality modeling of the projected impacts of these rules are summarized in the following section. 
1. Current Concentrations of Non-GHG 
Pollutants 
Nationally, levels of PM
2.5, ozone, 
NO X, SO X, CO, and air toxics have 
declined significantly in the last 30 years and are continuing to drop as previously promulgated regulations come into full effect. However, as of 
April 22, 2016, more than 125 million people lived in counties designated nonattainment for one or more of the NAAQS, and this figure does not include the people living in areas with a risk of exceeding a NAAQS in the future. Many Americans continue to be exposed to ambient concentrations of air toxics at levels which have the potential to cause adverse health effects. In addition, populations who live, work, or attend school near major roads experience elevated exposure concentrations to a wide range of air pollutants. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00364 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243349 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
77878 FR 47191, 81 FR 45049, 81 FR 89870, 83 
FR 1098, and 83 FR 14597. (a) Particulate Matter 
There are two primary NAAQS for 
PM 2.5: An annual standard (12.0 
micrograms per cubic meter ( mg/m3)) set 
in 2012 and a 24-hour standard (35 mg/ 
m3) set in 2006, and two secondary 
NAAQS for PM 2.5: An annual standard 
(15.0 mg/m3) set in 1997 and a 24-hour 
standard (35 mg/m3) set in 2006. 
There are many areas of the country 
that are currently in nonattainment for the annual and 24-hour primary PM
2.5 
NAAQS. As of April 22, 2016, more than 23 million people lived in the seven areas that are still designated as nonattainment for the 1997 annual PM
2.5NAAQS. These PM 2.5 
nonattainment areas are comprised of 33 full or partial counties. As of April 22, 2016, nine areas aredesignated as nonattainment for the 2012 annual PM
2.5NAAQS; these areas are composed 
of 20 full or partial counties with a population of more than 23 million. As of April 22, 2016, 16 areas are designated as nonattainment for the 2006 24-hour PM
2.5NAAQS, these areas 
are composed of 46 full or partial counties with a population of more than 32 million. In total, there are currently 24 PM
2.5nonattainment areas with a 
population of more than 39 million people. 
The EPA has already adopted many 
mobile source emission control programs that are expected to reduce ambient PM concentrations. As a result of these and other federal, state and local programs, the number of areas that fail to meet the PM
2.5NAAQS in the 
future is expected to decrease. However, even with the implementation of all current state and federal regulations, there are projected to be counties violating the PM
2.5NAAQS well into the 
future. States will need to meet the 2006 24-hour standards in the 2015–2019 timeframe and the 2012 primary annual standard in the 2021–2025 timeframe. Ozone 
The primary and secondary NAAQS 
for ozone are eight-hour standards with a level of 0.07 ppm. The most recent revision to the ozone standards was in 2015; the previous eight-hour ozone primary standard, set in 2008, had a level of 0.075 ppm. As of April 22, 2016, there were 44 ozone nonattainment areas for the 2008 ozone NAAQS, composed of 216 full or partial counties, with a population of more than 120 million. 
States with ozone nonattainment 
areas are required to take action to bring those areas into attainment. The attainment date assigned to an ozone nonattainment area is based on the area’s classification. The attainment dates for areas designated 
nonattainment for the 2008 eight-hour ozone NAAQS are in the 2015 to 2032 timeframe, depending on the severity of the problem in each area. Nonattainment area attainment dates associated with areas designated for the 2015 NAAQS will be in the 2020–2037 timeframe, depending on the severity of the problem in each area. 
EPA has already adopted many 
emission control programs that are expected to reduce ambient ozone levels. As a result of these and other federal, state and local programs, eight- hour ozone levels are expected to improve in the future. However, even with the implementation of all current state and federal regulations, there are projected to be counties violating the ozone NAAQS well into the future. 
(b) Nitrogen Dioxide 
On April 6, 2018, based on a review 
of the full body of scientific evidence, 
EPA issued a decision to retain the current national ambient air quality standards (NAAQS) for oxides of nitrogen (NO
X). The EPA has concluded 
that the current NAAQS protect the public health, including the at-risk populations of older adults, children and people with asthma, with an 
adequate margin of safety. The NAAQS for nitrogen oxides are a one-hour standard at a level of 100 ppb based on the three-year average of 98th percentile of the yearly distribution of one-hour daily maximum concentrations, and an annual standard at a level of 53 ppb. 
(c) Sulfur Dioxide 
The EPA is currently reviewing the 
primary SO
2NAAQS and has proposed 
to retain the current primary standard 
(83 FR 26752, June 8, 2018), which is a one-hour standard of 75 ppb established in June 2010. The EPA has been finalizing the initial area designations for the 2010 SO
2NAAQS in phases and 
completed designations for most of the country in December 2017. The EPA is under a court order to finalize initial designations by December 31, 2020, for a remaining set of about 50 areas where states have deployed new SO
2 
monitoring networks. As of July 2018, the EPA has designated 42 areas as nonattainment for the 2010 SO
2NAAQS 
in actions taken in 2013, 2016, and 2017.
778There also remain nine 
nonattainment areas for the primary annual SO
2NAAQS set in 1971. (d) Carbon Monoxide 
There are two primary NAAQS for 
CO: An eight-hour standard (9 ppm) and 
a one-hour standard (35 ppm). The primary NAAQS for CO were retained in August 2011. There are currently no CO nonattainment areas; as of September 27, 2010, all CO nonattainment areas have been redesignated to attainment. 
The past designations were based on 
the existing community-wide monitoring network. EPA is making changes to the ambient air monitoring requirements for CO. The new requirements are expected to result in approximately 52 CO monitors operating near roads within 52 urban areas by January 2015 (76 FR 54294, August 31, 2011). 
(e) Diesel Exhaust PM 
Because DPM is part of overall 
ambient PM and cannot be easily 
distinguished from overall PM, we do not have direct measurements of DPM in the ambient air. DPM concentrations are estimated using ambient air quality modeling based on DPM emission inventories. DPM emission inventories are computed as the exhaust PM emissions from mobile sources combusting diesel or residual oil fuel. DPM concentrations were recently estimated as part of the 2011 NATA. Areas with high concentrations are clustered in the Northeast, Great Lake States, California, and the Gulf Coast States and are also distributed throughout the rest of the U.S. The median DPM concentration calculated nationwide is 0.76 mg/m3. 
(f) Air Toxics 
The most recent available data 
indicate that the majority of Americans continue to be exposed to ambient concentrations of air toxics at levels which have the potential to cause adverse health effects. The levels of air toxics to which people are exposed vary depending on where people live and work and the kinds of activities in which they engage, as discussed in detail in EPA’s most recent Mobile Source Air Toxics Rule. According to the National Air Toxic Assessment (NATA) for 2015, mobile sources were responsible for 50% of outdoor anthropogenic toxic emissions and were the largest contributor to cancer and noncancer risk from directly emitted pollutants. Mobile sources are also large contributors to precursor emissions which react to form air toxics. Formaldehyde is the largest contributor to cancer risk of all 71 pollutants quantitatively assessed in the 2011 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00365 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243350 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
NATA. Mobile sources were responsible 
for more than 25% of primary anthropogenic emissions of this pollutant in 2011 and are major contributors to formaldehyde precursor emissions. Benzene is also a large contributor to cancer risk, and mobile sources account for almost 80% of ambient exposure. Over the years, EPA 
has implemented a number of mobile source and fuel controls which have resulted in VOC reductions, which also reduced formaldehyde, benzene and other air toxic emissions. 
2. Air Quality Impacts of Non-GHG 
Pollutants 
(a) Impacts of Proposed Standards on 
Future Ambient Concentrations of PM
2.5, Ozone and Air Toxics 
Full-scale photochemical air quality 
modeling is necessary to accurately project levels of criteria pollutants and air toxics. For the final rule, a national- scale air quality modeling analysis will be performed to analyze the impacts of the standards on PM
2.5, ozone, and 
selected air toxics (i.e., benzene, 
formaldehyde, acetaldehyde, acrolein and 1,3-butadiene). The length of time needed to prepare the necessary emissions inventories, in addition to the processing time associated with the modeling itself, has precluded us from performing air quality modeling for this proposal. 
Section VI.D.2 of the preamble 
present projections of the changes in criteria pollutant and air toxics emissions because of the proposed vehicle standards; the basis for those estimates is set out in Chapter 10 of the PRIA. The atmospheric chemistry related to ambient concentrations of PM
2.5, ozone and air toxics is very 
complex, and making predictions based solely on emissions changes is extremely difficult. 
3. Other Unquantified Health and 
Environmental Effects 
In addition, the agencies seek 
comment on whether there are any other health and environmental impacts associated with advancements in technologies that should be considered. For example, the use of technologies and other strategies to reduce fuel consumption and/or GHG emissions could have effects on a vehicle’s life- cycle impacts (e.g., materials usage, 
manufacturing, end of life disposal), beyond the issues regarding fuel production and distribution (upstream) GHG emissions discussed in Section VI.D.2. The agencies seek comment on any studies or research in this area that should be considered in the future to assess a fuller range of health and environmental impacts from the light- duty vehicle fleet shifting to different technologies and/or materials. At this point, it is unclear whether there is sufficient information about the lifecycle impacts of the myriad of available technologies, materials, and cradle-to-grave pathways to conduct the type of detailed assessments that would be needed in a regulatory context, but the agencies seek comment on any current or future studies and research underway on this topic, and how such analysis could practicably and in a balanced way be integrated in the modeling, especially considering the characterization of specific vehicles in the analysis fleet and the characterization of specific technology options. 
G. What are the impacts on the total 
fleet size, usage, and safety? 
1. CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00366 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243351 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
2. CO 2Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00367 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.249</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243352 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
779The CAFE model and all inputs and outputs 
supporting today’s proposal are available at https:// www.nhtsa.gov/corporate-average-fuel-economy/ 
compliance-and-effects-modeling-system. 78083 FR 13904 (Apr. 2, 2018). 
H. What other impacts (quantitative and 
unquantifiable) will these proposed standards have? 
1. Sensitivity Analysis 
As discussed at the beginning of this 
section, results presented today reflect 
the agencies’ best judgments regarding many different factors. Based on analyses in past rulemakings, the agencies recognize that some analytical 
inputs are especially uncertain, some are likely to exert considerable influence over specific types of estimated impacts, and some are likely 
to do so for the bulk of the analysis. To explore the sensitivity of estimated impacts to changes in model inputs, analysis was conducted using alternative values for a range of different inputs. Results of this sensitivity analysis are summarized below, and detailed model inputs and outputs are available on NHTSA’s website.
779 
Regulatory alternatives are identical across all cases, except that one case includes an increase in civil penalty rate starting in MY 2019; NHTSA may consider changing the civil penalty rate in a separate regulatory action, and depending on the timing of any such action, the final rule to follow today’s proposal could reflect the change.
780 
The following table lists the cases included in the sensitivity analysis. The final rule could adopt any combination—or none—of these alternatives as reference case inputs, and the agencies invite comment on all of them. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00368 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.250</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243353 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00369 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.251</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243354 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00370 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.252</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243355 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
781Climate-related economic damages caused by 
emissions of GHGs other than CO 2were estimated 
by converting those emissions to their (mass) 
equivalents in CO 2emissions and applying the per- 
ton damage costs used to monetize CO 2emissions. 
Specifically, emissions of methane (CH 4) and 
nitrous oxide (N 2O) were converted to their 
equivalent in CO 2emissions using the 100-year 
Global Warming Potentials (GWPs) for those gases, which are 25 for CH 4and 298 for N 2O. These GWPs 
were estimated by the United Nations Intergovernmental Panel on Climate Change in its 4th Assessment Report (available at https://www.ipcc.ch/publications_ and_ data/ar4/wg1/en/ 
ch2s2-10-2.html; last accessed July 19, 2018). An alternative approach would be to develop direct estimates of the climate damage costs for these GHGs derived using the same process that was used to estimate the SCC, described previously in PRIA Chapter 8.11.2 and the Appendix to Chapter 8. For 
comparison, using the alternative approach results in estmates which average $256 per (metric) ton for CH
4and $2,820 for N 2O over the analysis period, 
or about 22% and 13% higher than the values used in this sensitivity case. A detailed description of the methods used to construct these alternative values is available in the docket for this rule. The agency will consider using this alternative approach in its analysis supporting the final rule. 
The remaining tables in the section 
summarize various estimated impacts as 
estimated for all of the cases included in the sensitivity analysis. 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00371 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.253</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243356 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00372 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.254</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243357 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00373 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.255</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243358 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00374 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.256</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243359 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00375 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.257</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243360 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00376 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.258</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243361 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00377 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.259</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243362 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00378 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.260</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243363 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00379 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.261</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243364 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00380 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.262</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243365 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00381 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.263</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243366 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00382 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.264</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243367 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00383 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.265</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243368 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00384 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.266</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243369 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VIII. Impacts of Alternative CAFE and 
CO 2Standards Considered for MYs 
2021/22–2026 
As discussed above, a range of 
regulatory alternatives are being considered. Section III defines the proposed preferred alternative, and Section IV defines the no-action alternative as well as the other seven alternatives. The potential impacts of each alternative in each case relative to the no-action alternative were estimated. For the preferred alternative, these impacts are presented above on an incremental basis, such that the impacts attributed separately to standards proposed in each model year. To facilitate comparison of different alternatives, total estimated impacts 
(i.e., summing impacts attributable to all 
model years’ standards) were calculated 
under each alternative. 
Tables in the remaining section 
summarize these estimated impacts for each alternative, considering the same measures as shown above for the preferred alternative. As for the preferred alternative, social costs and benefits, private costs and benefits, and environmental and energy impacts were evaluated, and were done so separately for CAFE and CO
2standards defining 
each regulatory alternative. Also, as for the preferred alternative, the compliance-related private costs and benefits were evaluated separately for domestic and imported passenger cars 
under CAFE standards but not under CO
2standards because EPCA/EISA’s 
requirement for separate compliance 
applies only to CAFE standards. 
This analysis does not explicitly 
identify ‘‘co-benefits’’ from its proposed action to change fuel economy standards, as such a concept would include all benefits other than cost savings to vehicle buyers. Instead, it distinguishes between private benefits— which include economic impacts on vehicle manufacturers, buyers of new cars and light trucks, and owners (or users) of used cars and light trucks—and external benefits, which represent indirect benefits (or costs) to the 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00385 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.267</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243370 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
remainder of the U.S. economy that 
stem from the proposal’s effects on the behavior of vehicle manufacturers, buyers, and users. In this accounting framework, changes in fuel use and safety impacts resulting from the proposal’s effects on the number of used vehicles in use represent an important component of its private benefits and costs, despite the fact that previous analyses have failed to recognize these effects. The agency’s presentation of private costs and benefits from its proposed action clearly distinguishes between those that would be experienced by owners and users of cars and light trucks produced during previous model years, and those that would be experienced by buyers and 
users of cars and light trucks produced during the model years it would affect. Moreover, it clearly separates these into benefits related to fuel consumption and those related to safety consequences of vehicle use. This is more meaningful and informative than simply identifying all impacts other than changes in fuel savings to buyers of new vehicles as ‘‘co-benefits.’’ 
Like the preferred alternative, all 
other alternatives involve standards less stringent than the no-action alternative. 
Therefore, as discussed above, incremental benefits and costs for each alternative are negative—in other words, each alternative involves foregone benefits and avoided costs. Environmental and energy impacts are 
correspondingly negative, involving foregone avoided CO
2emissions and 
foregone avoided fuel consumption. For consistency with past rulemakings, these are reported as negative values rather than as additional CO
2emissions 
and additional fuel consumption. 
As discussed above, more detailed 
results are available in the PRIA and 
DEIS accompanying today’s notice, as well as in underlying model output files posted on NHTSA’s website. 
A. What are the social costs and benefits 
of each alternative, relative to the no- action alternative? 
1. CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00386 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243371 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00387 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.268</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243372 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00388 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.269</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243373 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00389 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.270</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243374 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00390 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.271</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243375 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00391 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.272</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243376 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00392 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.273</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243377 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00393 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.274</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243378 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00394 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.275</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243379 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00395 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.276</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243380 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00396 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.277</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243381 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00397 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.278</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243382 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00398 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.279</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243383 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00399 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.280</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243384 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00400 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.281</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243385 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00401 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.282</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243386 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00402 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.283</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243387 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00403 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.284</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243388 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00404 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.285</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243389 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
B. What are the private costs and 
benefits of each alternative, relative to the no-action alternative? 
1. What are the impacts on producers of 
new vehicles? 
(a) CAFE Standards 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00405 Fmt 4701 Sfmt 4702 E:\FR\FM\24AUP2.SGM 24AUP2sradovich on DSK3GMQ082PROD with PROPOSALS243390 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00406 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.286</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243391 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00407 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.287</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243392 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00408 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.500</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243393 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00409 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.501</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243394 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00410 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.502</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS243395 Federal Register / Vol. 83, No. 165 / Friday, August 24, 2018 / Proposed Rules 
VerDate Sep<11>2014 23:42 Aug 23, 2018 Jkt 244001 PO 00000 Frm 00411 Fmt 4701 Sfmt 4725 E:\FR\FM\24AUP2.SGM 24AUP2
EP24AU18.503</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2