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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49553 

BILLING CODE 4910–59–C 

First, note that the scale in Figure 

III.D.6–2 is much smaller by a factor of 

3 than that in Figure III.D.6–1. In other 

words, accounting for differences in 

vehicle weight (at constant footprint) 

and performance dramatically reduces 

the differences in various 

manufacturers’ CO2 emissions. Most of 

the manufacturers with high offsets in 

Figure III.D.6–1 now show low or 

negative offsets. For example, BMW’s 

and VW’s trucks show very low CO2 

emissions. Tata’s emissions are very 

close to the industry average. Daimler’s 

vehicles are no more than 10 g/mi above 

the average for the industry. This 

analysis indicates that the primary 

reasons for the differences in technology 

penetrations shown for the various 

manufacturers in Table III.D.6–3 are 

weight and performance. EPA has not 

determined why some manufacturers’ 

vehicle weight is relatively high for its 

footprint value, or whether this weight 

provides additional utility for the 

consumer. Performance is more 
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49554 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

straightforward. Some consumers desire 

high performance and some 

manufacturers orient their sales towards 

these consumers. However, the cost in 

terms of CO2 emissions is clear. 

Producing relatively heavy or high 

performance vehicles increases CO2 

emissions and will require greater levels 

of technology in order to meet the 

proposed CO2 standards. 

As can be seen from Table III.D.6–3 

above, widespread use of several 

technologies is projected due to the 

proposed standards. The vast majority 

of engines are projected to be converted 

to direct injection, with some of these 

engines including cylinder deactivation 

or turbocharging and downsizing. More 

than 60 percent of all transmissions are 

projected to be either high speed 

automatic transmissions or dual-clutch 

automated manual transmissions. More 

than one third of the fleet is projected 

to be equipped with 42 volt start-stop 

capability. This technology was not 

utilized in 2008 vehicles, but as 

discussed above, promises significant 

fuel efficiency improvement at a 

moderate cost. 

EPA foresees no significant technical 

or engineering issues with the projected 

deployment of these technologies across 

the fleet, with their incorporation being 

folded into the vehicle redesign process. 

All of these technologies are 

commercially available now. The 

automotive industry has already begun 

to convert its port fuel-injected gasoline 

engines to direct injection. Cylinder 

deactivation and turbocharging 

technologies are already commercially 

available. As indicated in Table III.D.6– 

1, high speed transmissions are already 

widely used. However, while more 

common in Europe, automated manual 

transmissions are not currently used 

extensively in the U.S. Widespread use 

of this technology would require 

significant capital investment but does 

not present any significant technical or 

engineering issues. Start-stop systems 

also represent a significant challenge 

because of the complications involved 

in a changeover to a higher voltage 

electrical architecture. However, with 

appropriate capital investments (which 

are captured in the costs), these 

technology penetration rates are 

achievable within the timeframe of this 

rule. While most manufacturers have 

some plans for these systems, our 

projections indicate that their use may 

exceed 35 percent of sales, with some 

manufacturers requiring higher levels. 

Most manufacturers would not have 

to hybridize any vehicles due to the 

proposed standards. The hybrids shown 

for Toyota are projected to be sold even 

in the absence of the proposed 

standards. However the relatively high 

hybrid penetrations (15%) projected for 

BMW, Daimler, Porsche, Tata and 

Volkswagen deserve further discussion. 

These manufacturers are all projected by 

the OMEGA model to utilize the 

maximum application of full hybrids 

allowed by our model in this time 

frame, which is 15 percent. 

As discussed in the EPA DRIA, a 2016 

technology penetration rate of 85% is 

projected for the vast majority of 

available technologies, however, for full 

hybrid systems the projection shows 

that given the available lead-time full 

hybrids can only be applied to 

approximately 15% of a manufacturer’s 

fleet. This number of course can vary by 

manufacturer. 

While the hybridization levels of 

BMW, Daimler, Porsche, Tata and 

Volkswagen are relatively high, the sales 

levels of these five manufacturers are 

relatively low. Thus, industry-wide, 

hybridization reaches only 8 percent, 

compared with 3 percent in the 

reference case. This 8 percent level is 

believed to be well within the capability 

of the hybrid component industry by 

2016. Thus, the primary challenge for 

these five companies would be at the 

manufacturer level, redesigning a 

relatively large percentage of sales to 

include hybrid technology. The 

proposed TLAAS provisions will 

provide significant aid to these 

manufacturers in pre-2016 compliance, 

since all qualified companies are 

expected to be able to take advantage of 

these provisions. By 2016, it is likely 

that these manufacturers would also be 

able to change vehicle characteristics 

which currently cause their vehicles to 

emit much more CO2 than similar sized 

vehicles produced by other 

manufacturers. These factors may 

include changes in model mix, further 

lightweighting, downpowering, electric 

and/or plug-in hybrid vehicles, or 

downsizing (our current baseline fleet 

assumes very little change in footprint 

from 2012–2016), as well as 

technologies that may not be included 

in our packages. Also, companies may 

have technology penetration rates of less 

costly technologies (listed in the above 

tables) greater than 85%, and they may 

also be able to apply hybrid technology 

to more than 15 percent of their fleet (as 

the 15% for hybrid technology is an 

industry average). For example, a switch 

to a low GWP alternative refrigerant in 

a large fraction of a fleet can replace 

many other much more costly 

technologies, but this option is not 

captured in the modeling. In addition, 

these manufacturers can also take 

advantage of flexibilities, such as early 

credits for air conditioning and trading 

with other manufacturers. The EPA 

expects that there will be certain high 

volume manufacturers that will earn a 

significant amount of early GHG credits 

starting in 2009 and 2010 that will 

expire 5 years later, by 2014 and 2015, 

unused. The EPA believes that these 

manufacturers will be willing to sell 

these expiring credits to manufacturers 

with whom there is no direct 

competition. Furthermore, some of these 

manufacturers have also stated either 

publicly or in confidential discussions 

with EPA that they will be able to 

comply with 2016 standards. Because of 

the confidential nature of this 

information sharing, EPA is unable to 

capture these packages specifically in 

our modeling. The following companies 

have all submitted letters in support of 

the national program, including the 

2016 MY levels discussed above: BMW, 

Chrysler, Daimler, Ford, GM, Honda, 

Mazda, Toyota, and Volkswagen. This 

supports the view that the emissions 

reductions needed to achieve the 

standards are technically and 

economically feasible for all these 

companies, and that EPA’s projection of 

non-compliance for four of the 

companies is based on an inability of 

our model to fully account for the full 

flexibilities of the EPA program as well 

as the potentially unique technology 

approaches or new product offerings 

which these manufactures are likely to 

employ. 

In addition, manufacturers do not 

need to apply technology exactly 

according to our projections. Our 

projections simply indicate one path 

which would achieve compliance. 

Those manufacturers whose vehicles are 

heavier and higher performing than 

average in particular have additional 

options to facilitate compliance and 

reduce their technological burden closer 

to the industry average. These options 

include decreasing the mass of the 

vehicles and/or decreasing the power 

output of the engines. Finally, EPA 

allows compliance to be shown through 

the use of emission credits obtained 

from other manufacturers. Especially for 

the lower volume sales of some 

manufacturers that could be one 

component of an effective compliance 

strategy, reducing the technology that 

needs to be employed on their vehicles. 

For the vast majority of light-duty cars 

and trucks, manufacturers have 

available to them a range of technologies 

that are currently commercially 

available and can feasibly be employed 

in their vehicles by MY 2016. Our 

modeling projects widespread use of 

these technologies as a technologically 

feasible approach to complying with the 

proposed standards. 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49555 

In sum, EPA believes that the approaches and compliance flexibilities associated with the proposed 2016 CO2 

emissions reductions called for by the not fully reflected in our modeling. emission standards. The latter costs are 

proposed standards are technologically EPA also projected the cost associated incremental to those associated with the

feasible, based on projections of with these projections of technology 2011 MY standards and also include

widespread use of commercially penetration. Table III.D.6–4 shows the $60 per vehicle, on average, for the cost cost of technology in order for available technology, as well as use by of projected use of improved air- manufacturers to comply with the 2011 some manufacturers of other technology conditioning systems.163 

MY CAFE standards, as well as those 

TABLE III.D.6–4—COST OF TECHNOLOGY PER VEHICLE IN 2016 ($2007) 

2011 MY CAFE standards Proposed 2016 CO2 standards 

Cars Trucks All Cars Trucks All 

BMW ................................................................................ $319 $479 $361 $1,701 $1,665 $1,691 

Chrysler ............................................................................ 7 125 59 1,331 1,505 1,408 

Daimler ............................................................................. 431 632 495 1,631 1,357 1,543 

Ford .................................................................................. 28 211 109 1,435 1,485 1,457 

General Motors ................................................................ 28 136 73 969 1,782 1,311 

Honda ............................................................................... 0 0 0 606 695 633 

Hyundai ............................................................................ 0 76 14 739 1,680 907 

Kia .................................................................................... 0 48 8 741 1,177 812 

Mazda .............................................................................. 0 0 0 946 1,030 958 

Mitsubishi ......................................................................... 96 322 123 1,067 1,263 1,090 

Nissan .............................................................................. 0 19 6 1,013 1,194 1,064 

Porsche ............................................................................ 535 1,074 706 1,549 666 1,268 

Subaru .............................................................................. 64 100 77 903 1,329 1,057 

Suzuki .............................................................................. 99 231 133 1,093 1,263 1,137 

Tata .................................................................................. 691 1,574 1,161 1,270 674 952 

Toyota .............................................................................. 0 0 0 600 436 546 

Volkswagen ...................................................................... 269 758 354 1,626 949 1,509 

Overall .............................................................................. 47 141 78 968 1,214 1,051 

As can be seen, the industry average 

cost of complying with the 2011 MY 

CAFE standards is quite low, $78 per 

vehicle. The range of costs across 

manufacturers is quite large, however. 

Honda, Mazda and Toyota are projected 

to face no cost, while Daimler, Porsche 

and Tata face costs of at least $495 per 

vehicle. As described above, these last 

three manufacturers face such high costs 

to meet even the 2011 MY CAFE 

standards due to both their vehicles’ 

weight per unit footprint and 

performance. Also, these cost estimates 

apply to sales in the 2016 MY. These 

three manufacturers, as well as others 

like Volkswagen, may choose to pay 

CAFE fines prior to this or even in 2016. 

As shown in the last row of Table 

III.D.6–4, the average cost of technology 

to meet the proposed 2016 standards for 

cars and trucks combined relative to the 

2011 MY CAFE standards is $1051 per 

vehicle. The projection shows that the 

average cost for cars would be slightly 

lower than that for trucks. Toyota and 

Honda show projected costs 

significantly below the average, while 

BMW, Porsche, Tata and Volkswagen 

show significantly higher costs. On 

average, the $1051 per vehicle cost is 

significant, representing roughly 5% of 

the total cost of a new vehicle. However, 

as discussed below, the fuel savings 

associated with the proposed standards 

exceeds this cost significantly. 

While the CO2 emission compliance 

modeling using the OMEGA model 

focused on the proposed 2016 MY 

standards, EPA believes that the 

proposed standards for 2012–2015 

would also be feasible. As discussed 

above, EPA believes that manufacturers 

develop their vehicle designs with 

several model years in view. Generally, 

the technology estimated above for 2016 

MY vehicles represents the technology 

which would be added to those vehicles 

which are being redesigned in 2012– 

2015. The proposed CO2 standards for 

2012–2016 reduce CO2 emissions at a 

fairly steady rate. Thus, manufacturers 

which redesign their vehicles at a fairly 

steady rate will automatically comply 

with the interim standard as they plan 

for compliance in 2016. 

Manufacturers which redesign much 

fewer than 20% of their sales in the 

early years of the proposed program 

would face a more difficult challenge, as 

simply implementing the ‘‘2016 MY’’ 

technology as vehicles are redesigned 

may not enable compliance in the early 

years. However, even in this case, 

manufacturers would have several 

options to enable compliance. One, they 

could utilize the proposed debit carryforward provisions described above. 

This may be sufficient alone to enable 

compliance through the 2012–2016 MY 

time period, if their redesign schedule 

exceeds 20% per year prior to 2016. If 

not, at some point, the manufacturer 

might need to increase their use of 

technology beyond that projected above 

in order to generate the credits 

necessary to balance the accrued debits. 

For most manufacturers representing the 

vast majority of U.S. sales, this would 

simply mean extending the same 

technology to a greater percentage of 

sales. The added cost of this in the later 

years of the program would be balanced 

by lower costs in the earlier years. Two, 

the manufacturer could buy credits from 

another manufacturer. As indicated 

above, several manufacturers are 

projected to require less stringent 

technology than the average. These 

manufacturers would be in a position to 

provide credits at a reasonable 

technology cost. Thus, EPA believes the 

proposed standards for 2012–2016 

would be feasible. 

7. What Other Fleet-Wide CO2 Levels 

Were Considered? 

Two alternative sets of CO2 standards 

were considered. One set would reduce 

163 Note that the actual cost of the A/C technology III.D.2–3. However, we expect only 85 percent of of the technology when spread across the entire 

is estimated at $78 per vehicle as shown in Table the fleet to add that technology. Therefore, the cost fleet is $66 per vehicle ($78×85%=$66). 
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49556 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

CO2 emissions at a rate of 4 percent per above for the proposed standards. The control scenarios were discussed above. 

year. The second set would reduce CO2 only difference was the level of CO2 The resultant CO2 standards in 2016 for 

emissions at a rate of 6 percent per year. emission standards. The footprint-based each manufacturer under these two 

The analysis of these standards followed standard coefficients of the car and alternative scenarios and under the 

the exact same process as described truck curves for these two alternative proposal are shown in Table III.D.7–1. 

TABLE III.D.7–1—OVERALL AVERAGE CO2 EMISSION STANDARDS BY MANUFACTURER IN 2016 

4% per 

year Proposed 6% per year 

BMW .................................................................................................................................................................... 245 241 222 

Chrysler ................................................................................................................................................................ 266 262 241 

Daimler ................................................................................................................................................................. 257 253 233 

Ford ...................................................................................................................................................................... 270 266 245 

General Motors .................................................................................................................................................... 272 268 247 

Honda .................................................................................................................................................................. 243 239 219 

Hyundai ................................................................................................................................................................ 235 231 212 

Kia ........................................................................................................................................................................ 237 234 215 

Mazda .................................................................................................................................................................. 231 227 208 

Mitsubishi ............................................................................................................................................................. 226 223 204 

Nissan .................................................................................................................................................................. 251 247 227 

Porsche ................................................................................................................................................................ 234 230 210 

Subaru ................................................................................................................................................................. 237 233 213 

Suzuki .................................................................................................................................................................. 227 223 203 

Tata ...................................................................................................................................................................... 267 263 241 

Toyota .................................................................................................................................................................. 247 243 223 

Volkswagen .......................................................................................................................................................... 233 230 211 

Overall .................................................................................................................................................................. 254 250 230 

Tables III.D.7–2 and III.D.7–3 show 4 percent per year and 6 percent per 

the technology penetration levels for the year standards in 2016. 

TABLE III.D.7–2—TECHNOLOGY PENETRATION—4% PER YEAR CO2 STANDARDS IN 2016: CARS AND TRUCKS COMBINED 

GDI GDI+ deac GDI+ turbo 6 Speed 

auto trans 

Dual clutch 

trans Start-stop Hybrid Mass reduction (%) 

BMW ................................ 4% 35% 47% 15% 71% 71% 14% 5 

Chrysler ............................ 47 25 3 33 48 48 0 5 

Daimler ............................. 3 44 39 11 73 72 13 5 

Ford .................................. 33 32 13 23 61 61 0 5 

General Motors ................ 33 25 7 19 48 48 0 5 

Honda ............................... 20 1 0 6 19 19 2 2 

Hyundai ............................ 27 2 12 2 39 39 0 3 

Kia .................................... 31 0 4 1 34 34 0 2 

Mazda .............................. 34 2 16 10 43 43 0 3 

Mitsubishi ......................... 65 2 7 28 60 60 0 6 

Nissan .............................. 34 22 2 40 51 51 1 5 

Porsche ............................ 7 36 49 10 70 70 15 4 

Subaru .............................. 46 4 14 10 54 46 0 3 

Suzuki .............................. 72 5 2 15 63 63 0 4 

Tata .................................. 4 81 0 14 70 70 15 6 

Toyota .............................. 25 2 0 30 33 5 13 1 

Volkswagen ...................... 9 26 58 12 72 70 15 4 

Overall .............................. 28 17 9 20 45 40 4 4 

Increase over 2011 CAFE 21 15 9 ¥5 42 38 1 4 

TABLE III.D.7–3—TECHNOLOGY PENETRATION—6% PER YEAR ALTERNATIVE STANDARDS IN 2016: CARS AND TRUCKS
 

COMBINED
 

GDI GDI+ deac GDI+ turbo 6 Speed 

auto trans 

Dual clutch 

trans Start-stop Hybrid Weight reduction (%) 

BMW ................................ 4% 35% 47% 15% 71% 71% 14% 5 

Chrysler ............................ 29 50 6 4 85 85 0 8 

Daimler ............................. 3 44 39 11 73 72 13 5 

Ford .................................. 8 37 40 4 74 74 11 7 

General Motors ................ 24 54 8 6 81 81 0 8 

Honda ............................... 38 1 15 8 50 50 2 4 

Hyundai ............................ 36 9 28 7 66 66 0 5 

Kia .................................... 48 0 25 18 55 55 0 4 

Mazda .............................. 65 2 16 4 81 76 0 6 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49557 

TABLE III.D.7–3—TECHNOLOGY PENETRATION—6% PER YEAR ALTERNATIVE STANDARDS IN 2016: CARS AND TRUCKS
 

COMBINED—Continued 


GDI GDI+ deac GDI+ turbo 6 Speed 

auto trans 

Dual clutch 

trans Start-stop Hybrid Weight reduction (%) 

Mitsubishi ......................... 59 7 19 7 80 80 5 8 

Nissan .............................. 34 17 35 9 76 76 10 7 

Porsche ............................ 7 36 49 10 70 70 15 4 

Subaru .............................. 66 4 14 0 85 80 0 6 

Suzuki .............................. 2 12 71 0 80 80 5 7 

Tata .................................. 4 81 0 14 70 70 15 6 

Toyota .............................. 40 7 11 25 50 50 13 3 

Volkswagen ...................... 9 26 58 12 72 70 15 4 

Overall .............................. 28 24 23 11 67 67 7 6 

Increase over 2011 CAFE 22 23 22 ¥15 65 65 4 6 

With respect to the 4 percent per year 

standards, the levels of requisite control 

technology decreased relative to those 

under the proposed standards, as would 

be expected. Industry-wide, the largest 

decrease was a 2 percent decrease in the 

application of start-stop technology. On 

a manufacturer specific basis, the most 

significant decreases were a 6 percent 

decrease in hybrid penetration for BMW 

and a 2 percent drop for Daimler. These 

are relatively small changes and are due 

to the fact that the 4 percent per year 

standards only require 4 g/mi CO2 less 

control than the proposed standards in 

2016. Porsche, Tata and Volkswagen 

continue to be unable to comply with 

the CO2 standards in 2016. 

With respect to the 6 percent per year 

standards, the levels of requisite control 

technology increased relative to those 

under the proposed standards, as again 

would be expected. Industry-wide, the 

largest increase was an 8 percent 

increase in the application of start-stop 

technology. On a manufacturer specific 

basis, the most significant increases 

were a 42 percent increase in hybrid 

penetration for BMW and a 38 percent 

increase for Daimler. These are more 

significant changes and are due to the 

fact that the 6 percent per year 

standards require 20 g/mi CO2 more 

control than the proposed standards in 

2016. Porsche, Tata and Volkswagen 

continue to be unable to comply with 

the CO2 standards in 2016. However, 

BMW joins this list, as well, though just 

by 1 g/mi. Most manufacturers 

experience the increase in start-stop 

technology application, with the 

increase ranging from 5 to 17 percent. 

Table III.D.7–4 shows the projected 

cost of the two alternative sets of 

standards. 

TABLE III.D.7–4—TECHNOLOGY COST PER VEHICLE IN 2016—ALTERNATIVE STANDARDS ($2007) 

4 Percent per year standards 6 Percent per year standards 

Cars Trucks All Cars Trucks All 

BMW ................................................................................ $1,701 $1,665 $1,691 $1,701 $1,665 $1,691 

Chrysler ............................................................................ 1,340 1,211 1,283 1,642 2,211 1,893 

Daimler ............................................................................. 1,631 1,357 1,543 1,631 1,357 1,543 

Ford .................................................................................. 1,429 1,305 1,374 2,175 2,396 2,273 

General Motors ................................................................ 969 1,567 1,221 1,722 2,154 1,904 

Honda ............................................................................... 633 402 564 777 1,580 1,016 

Hyundai ............................................................................ 685 1,505 832 1,275 1,680 1,347 

Kia .................................................................................... 741 738 741 1,104 1,772 1,213 

Mazda .............................................................................. 851 914 860 1,369 1,030 1,320 

Mitsubishi ......................................................................... 1,132 247 1,028 1,495 2,065 1,563 

Nissan .............................................................................. 910 1,194 991 1,654 2,274 1,830 

Porsche ............................................................................ 1,549 666 1,268 1,549 666 1,268 

Subaru .............................................................................. 903 1,131 985 1,440 1,615 1,503 

Suzuki .............................................................................. 1,093 1,026 1,076 1,718 2,219 1,846 

Tata .................................................................................. 1,270 674 952 1,270 674 952 

Toyota .............................................................................. 518 366 468 762 1,165 895 

Volkswagen ...................................................................... 1,626 949 1,509 1,626 949 1,509 

Overall .............................................................................. 940 1,054 978 1,385 1,859 1,544 

As can be seen, the average cost of the 

4 percent per year standards is only $73 

per vehicle less than that for the 

proposed standards. In contrast, the 

average cost of the 6 percent per year 

standards is nearly $500 per vehicle 

more than that for the proposed 

standards. Compliance costs are 

entering the region of non-linearity. The 

$73 cost savings of the 4 percent per 

year standards relative to the proposal 

represents $18 per g/mi CO2 increase. 

The $493 cost increase of the 6 percent 

per year standards relative to the 

proposal represents $25 per g/mi CO2 

increase. 

EPA does not believe the 4% per year 

alternative is an appropriate standard 

for the MY2012–2016 time frame. As 

discussed above, the 250 g/mi proposal 

is technologically feasible in this time 

frame at reasonable costs, and provides 

higher GHG emission reductions at a 

modest cost increase over the 4% per 

year alternative (less than $100 per 

vehicle). In addition, the 4% per year 

alternative does not result in a 

harmonized National Program for the 

country. Based on California’s letter of 

May 18, 2009, the emission standards 

under this alternative would not result 

in the State of California revising its 

regulations such that compliance with 
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49558 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

EPA’s GHG standards would be deemed 

to be in compliance with California’s 

GHG standards for these model years. 

Thus, the consequence of promulgating 

a 4% per year standard would be to 

require manufacturers to produce two 

vehicle fleets: a fleet meeting the 4% per 

year Federal standard, and a separate 

fleet meeting the more stringent 

California standard for sale in California 

and the section 177 States. This further 

increases the costs of the 4% per year 

standard and could lead to additional 

difficulties for the already stressed 

automotive industry. 

EPA also does not believe the 6% per 

year alternative is an appropriate 

standard for the MY 2012–2016 time 

frame. As shown in Tables III.D.7–3 and 

III.D.7–4, the 6% per year alternative 

represents a significant increase in both 

the technology required and the overall 

costs compared to the proposed 

standards. In absolute percent increases 

in the technology penetration, compared 

to the proposed standards the 6% per 

year alternative requires for the industry 

as a whole: an 18% increase in GDI fuel 

systems, an 11% increase in turbodownsize systems, a 6% increase in 

dual-clutch automated manual 

transmissions (DCT), and a 9% increase 

in start-stop systems. For a number of 

manufacturers the expected increase in 

technology is greater: for GM, a 15% 

increase in both DCTs and start-stop 

systems, for Nissan a 9% increase in full 

hybrid systems, for Ford an 11% 

increase in full hybrid systems, for 

Chrysler a 34% increase in both DCT 

and start-stop systems and for Hyundai 

a 23% increase in the overall 

penetration of DCT and start-stop 

systems. For the industry as a whole, 

the per-vehicle cost increase for the 6% 

per year alternative is nearly $500. On 

average this is a 50% increase in costs 

compared to the proposed standards. At 

the same time, CO2 emissions would be 

reduced by about 8%, compared to the 

250 g/mi target level. 

These technology and cost increases 

are significant, given the amount of 

lead-time between now and model years 

2012–2016. In order to achieve the 

levels of technology penetration for the 

proposed standards, the industry needs 

to invest significant capital and product 

development resources right away, in 

particular for the 2012 and 2013 model 

year, which is only 2–3 years from now. 

For the 2014–2016 time frame, 

significant product development and 

capital investments will need to occur 

over the next 2–3 year in order to be 

ready for launching these new products 

for those model years. Thus a major part 

of the required capital and resource 

investment will need to occur in the 

next few years, under the proposed 

standards. EPA believes that the 

proposal (a target of 250 gram/mile in 

2016) already requires significant 

investment and product development 

costs for the industry, focused on the 

next few years. 

It is important to note, and as 

discussed later in this preamble, as well 

as in the draft Joint Technical Support 

Document and the draft EPA Regulatory 

Impact Analysis document, the average 

model year 2016 per-vehicle cost 

increase of nearly $500 includes an 

estimate of both the increase in capital 

investments by the auto companies and 

the suppliers as well as the increase in 

product development costs. These costs 

can be significant, especially as they 

must occur over the next 2–3 years. 

Both the domestic and transplant auto 

firms, as well as the domestic and 

world-wide automotive supplier base, is 

experiencing one of the most difficult 

markets in the U.S. and internationally 

that has been seen in the past 30 years. 

One major impact of the global 

downturn in the automotive industry 

and certainly in the U.S. is the 

significant reductions in product 

development engineers and staffs, as 

well as a tightening of the credit markets 

which allow auto firms and suppliers to 

make the near-term capital investments 

necessary to bring new technology into 

production. EPA is concerned that the 

significantly increased pressure on 

capital and other resources from the 6% 

per year alternative may be too stringent 

for this time frame, given both the 

relatively limited amount of lead-time 

between now and model years 2012– 

2016, the need for much of these 

resources over the next few years, as 

well the current financial and related 

circumstances of the automotive 

industry. EPA is not concluding that the 

6% per year alternative standards are 

technologically infeasible, but EPA 

believes such standards for this time 

frame would be overly stringent given 

the significant strain it would place on 

the resources of the industry under 

current conditions. EPA believes this 

degree of stringency is not warranted at 

this time. Therefore EPA does not 

believe the 6% per year alternative 

would be an appropriate balance of 

various relevant factors for model years 

2012–1016. 

These alternative standards represent 

two possibilities out of many. The EPA 

believes that the current proposed 

standards represent an appropriate 

balance of the factors relevant under 

section 202(a). For further discussion of 

this issue, see Chapter 4 of the DRIA. 

E. Certification, Compliance, and 

Enforcement 

1. Compliance Program Overview 

This section of the preamble describes 

EPA’s proposal for a comprehensive 

program to ensure compliance with 

EPA’s proposed emission standards for 

carbon dioxide (CO2), nitrous oxide 

(N2O), and methane (CH4), as described 

in Section III.B. An effective compliance 

program is essential to achieving the 

environmental and public health 

benefits promised by these mobile 

source GHG standards. EPA’s proposal 

for a GHG compliance program is 

designed around two overarching 

priorities: (1) To address Clean Air Act 

(CAA) requirements and policy 

objectives; and (2) to streamline the 

compliance process for both 

manufacturers and EPA by building on 

existing practice wherever possible, and 

by structuring the program such that 

manufacturers can use a single data set 

to satisfy both the new GHG and 

Corporate Average Fuel Economy 

(CAFE) testing and reporting 

requirements. The program proposed by 

EPA and NHTSA recognizes, and 

replicates as closely as possible, the 

compliance protocols associated with 

the existing CAA Tier 2 vehicle 

emission standards, and with CAFE 

standards. The certification, testing, 

reporting, and associated compliance 

activities closely track current practices 

and are thus familiar to manufacturers. 

EPA already oversees testing, collects 

and processes test data, and performs 

calculations to determine compliance 

with both CAFE and CAA standards. 

Under this proposed coordinated 

approach, the compliance mechanisms 

for both programs are consistent and 

non-duplicative. 

Vehicle emission standards 

established under the CAA apply 

throughout a vehicle’s full useful life. In 

this case EPA is proposing fleet average 

standards where compliance with the 

fleet average is determined based on the 

testing performed at time of production, 

as with the current CAFE fleet average. 

EPA is also proposing in-use standards 

that apply throughout a vehicle’s useful 

life, with the standard determined by 

adding a 10% adjustment factor to the 

model-level emission results used to 

calculate the fleet average. Therefore, 

EPA’s proposed program must not only 

assess compliance with the fleet average 

standards described in Section III.B, but 

must also assess compliance with the 

in-use standards. As it does now, EPA 

would use a variety of compliance 

mechanisms to conduct these 

assessments, including pre-production 

certification and post-production, in-use 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49559 

monitoring once vehicles enter 

customer service. Specifically, EPA is 

proposing a compliance program for the 

fleet average that utilizes CAFE program 

protocols with respect to testing, a 

certification procedure that operates in 

conjunction with the existing CAA Tier 

2 certification procedures, and 

assessment of compliance with the inuse standards concurrent with existing 

EPA and manufacturer Tier 2 emission 

compliance testing programs. Under the 

proposed compliance program 

manufacturers would also be afforded 

numerous flexibilities to help achieve 

compliance, both stemming from the 

program design itself in the form of a 

manufacturer-specific CO2 fleet average 

standard, as well as in various credit 

banking and trading opportunities, as 

described in Section III.C. EPA’s 

proposed compliance program is 

outlined in further detail below. EPA 

requests comment on all aspects of the 

compliance program design including 

comments about whether differences 

between the proposed compliance 

scheme for GHG and the existing 

compliance scheme for other regulated 

pollutants are appropriate. 

2. Compliance With Fleet-Average CO2 

Standards 

Fleet average emission levels can only 

be determined when a complete fleet 

profile becomes available at the close of 

the model year. Therefore, EPA is 

proposing to determine compliance 

with the fleet average CO2 standards 

when the model year closes out, as is 

currently the protocol under EPA’s Tier 

2 program as well as under the current 

CAFE program. The compliance 

determination would be based on actual 

production figures for each model and 

on model-level emissions data collected 

through testing over the course of the 

model year. Manufacturers would 

submit this information to EPA in an 

end-of-year report which is discussed in 

detail in Section III.E.5.h below. 

Manufacturers currently conduct their 

CAFE testing over an entire model year 

to maximize efficient use of testing and 

engineering resources. Manufacturers 

submit their CAFE test results to EPA 

and EPA conducts confirmatory fuel 

economy testing at its laboratory on a 

subset of these vehicles under EPA’s 

Part 600 regulations. EPA is proposing 

that manufacturers continue to perform 

the model level testing currently 

required for CAFE fuel economy 

performance and measure and report the 

CO2 values for all tests conducted. Thus, 

manufacturers will submit one data set 

in satisfaction of both CAFE and GHG 

requirements such that EPA’s proposed 

program would not impose additional 

timing or testing requirements on 

manufacturers beyond that required by 

the CAFE program. For example, 

manufacturers currently submit fuel 

economy test results at the 

subconfiguration and configuration 

levels to satisfy CAFE requirements. 

Under this proposal manufacturers 

would also submit CO2 values for the 

same vehicles. Section III.E.3 discusses 

how this will be implemented in the 

certification process. 

a. Compliance Determinations 

As described in Section III.B above, 

the fleet average standards would be 

determined on a manufacturer by 

manufacturer basis, separately for cars 

and trucks, using the proposed footprint 

attribute curves. Under this proposal, 

EPA would calculate the fleet average 

emission level using actual production 

figures and, for each model type, CO2 

emission test values generated at the 

time of a manufacturer’s CAFE testing. 

EPA would then compare the actual 

fleet average to the manufacturer’s 

footprint standard to determine 

compliance, taking into consideration 

use of averaging and/or other types of 

credits. 

Final determination of compliance 

with fleet average CO2 standards may 

not occur until several years after the 

close of the model year due to the 

flexibilities of carry-forward and carryback credits and the remediation of 

deficits (see Section III.C). A failure to 

meet the fleet average standard after 

credit opportunities have been 

exhausted could ultimately result in 

penalties and injunctive orders under 

the CAA as described in Section III.E.6 

below. 

EPA periodically provides mobile 

source emissions and fuel economy 

information to the public, for example 

through the annual Compliance 

Report 164 and Fuel Economy Trends 

Report.165 EPA plans to expand these 

reports to include GHG performance 

and compliance trends information, 

such as annual status of credit balances 

or debits, use of various credit 

programs, attained versus projected fleet 

average emission levels, and final 

compliance status for a model year after 

credit reconciliation occurs. We seek 

comment on all aspects of public 

164 2007 Progress Report Vehicle and Engine 

Compliance Activities; EPA–420–R–08–011; 

October 2008. This document is available 

electronically at http://www.epa.gov/otaq/about/ 

420r08011.pdf. 

165 Light-Duty Automotive Technology and FuelEconomy Trends: 1975 Through 2008; EPA–420–S– 

08–003; September 2008. This document is 

available electronically at http://www.epa.gov/otaq/ 

fetrends.htm. 

dissemination of GHG compliance 

information 

b. Required Minimum Testing for Fleet 

Average CO2 

As noted, EPA is proposing that the 

same test data required for determining 

a manufacturer’s compliance with the 

CAFE standard also be used to 

determine the manufacturer’s 

compliance with the fleet average CO2 

emissions standard. CAFE requires 

manufacturers to submit test data 

representing at least 90% of the 

manufacturer’s model year production, 

by configuration.166 The CAFE testing 

covers the vast majority of models in a 

manufacturer’s fleet. Manufacturers 

industry-wide currently test more than 

1,000 vehicles each year to meet this 

requirement. EPA believes this 

minimum testing requirement is 

necessary and applicable for calculating 

accurate CO2 fleet average emissions. 

Manufacturers may test additional 

vehicles, at their option. As described 

above, EPA would use the emissions 

results from the model-level testing to 

calculate a manufacturer’s fleet average 

CO2 emissions and to determine 

compliance with the CO2 standard. 

EPA is proposing to continue to allow 

certain testing flexibilities that exist 

under the CAFE program. EPA has 

always permitted manufacturers some 

ability to reduce their test burden in 

tradeoff for lower fuel economy 

numbers. Specifically the practice of 

‘‘data substitution’’ enables 

manufacturers to apply fuel economy 

test values from a ‘‘worst case’’ 

configuration to other configurations in 

lieu of testing them. The substituted 

values may only be applied to 

configurations that would be expected 

to have better fuel economy and for 

which no actual test data exist. 

Substituted data would only be 

accepted for the GHG program if it is 

also used for CAFE purposes. 

EPA’s regulations for CAFE fuel 

economy testing permit the use of 

analytically derived fuel economy data 

in lieu of an actual fuel economy test in 

certain situations.167 Analytically 

derived data is generated 

mathematically using expressions 

determined by EPA and is allowed on 

a limited basis when a manufacturer has 

not tested a specific vehicle 

configuration. This has been done as a 

means to reduce some of the testing 

burden on manufacturers without 

sacrificing accuracy in fuel economy 

measurement. EPA has issued guidance 

that provides details on analytically 

166 See 40 CFR 600.010–08(d). 


167 40 CFR 600.006–08(e). 

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49560 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

derived data and that specifies the 

conditions when analytically derived 

fuel economy may be used. EPA would 

also apply the same guidance to the 

GHG program and would allow any 

analytically derived data used for CAFE 

to also satisfy the GHG data reporting 

requirements. EPA would, however, 

need to revise the terms in the current 

equations for analytically derived fuel 

economy to specify them in terms of 

CO2. Analytically derived CO2 data 

would not be permitted for the Emission 

Data Vehicle representing a test group 

for pre-production certification, only for 

the determination of the model level test 

results used to determine actual fleetaverage CO2 levels. 

EPA is retaining the definitions 

needed to determine CO2 levels of each 

model type (such as ‘‘subconfiguration,’’ 

‘‘configuration,’’ ‘‘base level,’’ etc.) as 

they are currently defined in EPA’s fuel 

economy regulations. 

3. Vehicle Certification 

CAA section 203(a)(1) prohibits 

manufacturers from introducing a new 

motor vehicle into commerce unless the 

vehicle is covered by an EPA-issued 

certificate of conformity. Section 

206(a)(1) of the CAA describes the 

requirements for EPA issuance of a 

certificate of conformity, based on a 

demonstration of compliance with the 

emission standards established by EPA 

under section 202 of the Act. The 

certification demonstration requires 

emission testing, and must be done for 

each model year.168 

Under Tier 2 and other EPA emission 

standard programs, vehicle 

manufacturers certify a group of 

vehicles called a test group. A test group 

typically includes multiple vehicle car 

lines and model types that share critical 

emissions-related features.169 The 

manufacturer generally selects and tests 

one vehicle to represent the entire test 

group for certification purposes. The 

test vehicle is the one expected to be the 

worst case for the emission standard at 

issue. Emission results from the test 

vehicle are used to assign the test group 

to one of several specified bins of 

emissions levels, identified in the Tier 

2 rule, and this bin level becomes the 

in-use emissions standard for that test 

group.170 

168 CAA section 206(a)(1). 

169 The specific test group criteria are described 

in 40 CFR 86.1827–01, car lines and model types 

have the meaning given in 40 CFR 86.1803–01. 

170 Initially in-use standards were different from 

the bin level determined at certification as the 

useful life level. The current in-use standards, 

however, are the same as the bin levels. In all cases, 

the bin level, reflecting useful life levels, has been 

used for determining compliance with the fleet 

average. 

Since compliance with the Tier 2 fleet 

average depends on actual test group 

sales volumes and bin levels, it is not 

possible to determine compliance at the 

time the manufacturer applies for and 

receives a certificate of conformity for a 

test group. Instead, EPA requires the 

manufacturer to make a good faith 

demonstration in the certification 

application that vehicles in the test 

group will both (1) comply throughout 

their useful life with the emissions bin 

assigned, and (2) contribute to fleetwide 

compliance with the Tier 2 average 

when the year is over. EPA issues a 

certificate for the vehicles included in 

the test group based on this 

demonstration, and includes a condition 

in the certificate that if the manufacturer 

does not comply with the fleet average, 

then production vehicles from that test 

group will be treated as not covered by 

the certificate to the extent needed to 

bring the manufacturer’s fleet average 

into compliance with Tier 2. 

The certification process often occurs 

several months prior to production and 

manufacturer testing may occur months 

before the certificate is issued. The 

certification process for the Tier 2 

program is an efficient way for 

manufacturers to conduct the needed 

testing well in advance of certification, 

and to receive the needed certificates in 

a time frame which allows for the 

orderly production of vehicles. The use 

of a condition on the certificate has been 

an effective way to ensure compliance 

with the Tier 2 fleet average. 

EPA is proposing to similarly 

condition each certificate of conformity 

for the GHG program upon a 

manufacturer’s good faith 

demonstration of compliance with the 

manufacturer’s fleetwide average CO2 

standard. The following discussion 

explains how EPA proposes to integrate 

the proposed vehicle certification 

program into the existing certification 

program. 

a. Compliance Plans 

EPA is proposing that manufacturers 

submit a compliance plan to EPA prior 

to the beginning of the model year and 

prior to the certification of any test 

group. This plan would include the 

manufacturer’s estimate of its footprintbased standard (Section III.B), along 

with a demonstration of compliance 

with the standard based on projected 

model-level CO2 emissions, and 

production estimates. Manufacturers 

would submit the same information to 

NHTSA in the pre-model year report 

required for CAFE compliance. 

However, the GHG compliance plan 

could also include additional 

information relevant only to the EPA 

program. For example, manufacturers 

seeking to take advantage of air 

conditioning or other credit flexibilities 

(Section III.C) would include these in 

their compliance demonstration. 

Similarly, the compliance 

demonstration would need to include a 

credible plan for addressing deficits 

accrued in prior model years. EPA 

would review the compliance plan for 

technical viability and conduct a 

certification preview discussion with 

the manufacturer. EPA would view the 

compliance plan as part of the 

manufacturer’s good faith 

demonstration, but understands that 

initial projections can vary considerably 

from the reality of final production and 

emission results. EPA requests comment 

on the proposal to evaluate 

manufacturer compliance plans prior to 

the beginning of model year 

certification. EPA also requests 

comment on what criteria the agency 

should use to evaluate the sufficiency of 

the plan and on what steps EPA should 

take if it determines that a plan is 

unlikely to offset a deficit. 

b. Certification Test Groups and Test 

Vehicle Selection 

Manufacturers currently divide their 

fleet into ‘‘test groups’’ for certification 

purposes. The test group is EPA’s unit 

of certification; one certificate is issued 

per test group. These groupings cover 

vehicles with similar emission control 

system designs expected to have similar 

emissions performance.171 The factors 

considered for determining test groups 

include combustion cycle, engine type, 

engine displacement, number of 

cylinders and cylinder arrangement, 

fuel type, fuel metering system, catalyst 

construction and precious metal 

composition, among others. Vehicles 

having these features in common are 

generally placed in the same test 

group.172 Cars and trucks may be 

included in the same test group as long 

as they have similar emissions 

performance (manufacturers frequently 

produce cars and trucks that have 

identical engine designs and emission 

controls). 

EPA is proposing to retain the current 

Tier 2 test group structure for cars and 

light trucks in the certification 

requirements for CO2. At the time of 

certification, manufacturers would use 

the CO2 emission level from the Tier 2 

Emission Data Vehicle as a surrogate to 

represent all of the models in the test 

group. However, following certification 

171 40 CFR 86.1827–01. 172 EPA provides for other groupings in certain 

circumstances, and can establish its own test groups 

in cases where the criteria do not apply. 40 CFR 

86.1827–01(b), (c) and (d). 
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further testing would generally be 

required for compliance with the fleet 

average CO2 standard as described 

below. EPA’s issuance of a certificate 

would be conditioned upon the 

manufacturer’s subsequent model level 

testing and attainment of the actual fleet 

average. Further discussion of these 

requirements is presented in Section 

III.E.6. 

EPA recognizes that the Tier 2 test 

group criteria do not necessarily relate 

to CO2 emission levels. For instance, 

while some of the criteria, such as 

combustion cycle, engine type and 

displacement, and fuel metering, may 

have a relationship to CO2 emissions, 

others, such as those pertaining to the 

catalyst, may not. In fact, there are many 

vehicle design factors that impact CO2 

generation and emission but are not 

included in EPA’s test group criteria.173 

Most important among these may be 

vehicle weight, horsepower, 

aerodynamics, vehicle size, and 

performance features. 

EPA considered, but is not proposing, 

a requirement for separate CO2 test 

groups established around criteria more 

directly related to CO2 emissions. 

Although CO2-specific test groups might 

more consistently predict CO2 emissions 

of all vehicles in the test group, the 

addition of a CO2 test group requirement 

would greatly increase the preproduction certification burden for both 

manufacturers and EPA. For example, a 

current Tier 2 test group would need to 

be split into two groups if automatic and 

manual transmissions models had been 

included in the same group. Two- and 

four-wheel drive vehicles in a current 

test group would similarly require 

separation, as would weight differences 

among vehicles. This would at least 

triple the number of test groups. EPA 

believes that the added burden of 

creating separate CO2 test groups is not 

warranted or necessary to maintain an 

appropriately rigorous certification 

program because the test group data are 

later replaced by model specific data 

which are used as the basis for 

determining compliance with a 

manufacturer’s fleet average standard. 

EPA believes that the current test 

group concept is appropriate for N2O 

and CH4 because the technologies that 

would be employed to control N2O and 

CH4 emissions would generally be the 

same as those used to control the 

criteria pollutants. 

As just discussed, the ‘‘worst case’’ 

vehicle a manufacturer selects as the 

173 EPA noted this potential lack of connection 

between fuel economy testing and testing for 

emissions standard purposes when it first adopted 

fuel economy test procedures. See 41 FR at 38677 

(Sept. 10, 1976). 

Emissions Data Vehicle to represent a 

test group under Tier 2 (40 CFR 

86.1828–01) may not have the highest 

levels of CO2 in that group. For instance, 

there may be a heavier, more powerful 

configuration that would have higher 

CO2, but may, due to the way the 

catalytic converter has been matched to 

the engine, actually have lower NOX, 

CO, PM or HC. 

Therefore, in lieu of a separate CO2-

specific test group, EPA considered 

requiring manufacturers to select a CO2 

test vehicle from within the Tier 2 test 

group that would be expected, based on 

good engineering judgment, to have the 

highest CO2 emissions within that test 

group. The CO2 emissions results from 

this vehicle would be used to establish 

an in-use CO2 emission standard for the 

test group. The requirement for a 

separate, worst case CO2 vehicle would 

provide EPA with some assurance that 

all vehicles within the test group would 

have CO2 emission levels at or below 

those of the selected vehicle, even if 

there is some variation in the CO2 

control strategies within the test group 

(such as different transmission types). 

Under this approach, the test vehicle 

might or might not be the same one that 

would be selected as worst case for 

criteria pollutants. Thus, manufacturers 

might be required to test two vehicles in 

each test group, rather than a single 

vehicle. This would represent an added 

timing burden to manufacturers because 

they might need to build additional test 

vehicles at the time of certification that 

previously weren’t required to be tested. 

Instead, EPA is proposing to require a 

single Emission Data Vehicle that would 

represent the test group for both Tier 2 

and CO2 certification. The manufacturer 

would be allowed to initially apply the 

Emission Data Vehicle’s CO2 emissions 

value to all models in the test group, 

even if other models in the test group 

are expected to have higher CO2 

emissions. However, as a condition of 

the certificate, this surrogate CO2 

emissions value would generally be 

replaced with actual, model-level CO2 

values based on results from CAFE 

testing that occurs later in the model 

year. This model level data would 

become the official certification test 

results (as per the conditioned 

certificate) and would be used to 

determine compliance with the fleet 

average. Only if the test vehicle is in fact 

the worst case CO2 vehicle for the test 

group could the manufacturer elect to 

apply the Emission Data Vehicle 

emission levels to all models in the test 

group for purposes of calculating fleet 

average emissions. Manufacturers 

would be unlikely to make this choice, 

because doing so would ignore the 

emissions performance of vehicle 

models in their fleet with lower CO2 

emissions and would unnecessarily 

inflate their CO2 fleet average. Testing at 

the model level already occurs and data 

are already being submitted to EPA for 

CAFE and labeling purposes, so it 

would be an unusual situation that 

would cause a manufacturer to ignore 

these data and choose to accept a higher 

CO2 fleet average. 

EPA requests comment regarding 

whether the Tier 2 test group can 

adequately represent CO2 emissions for 

certification purposes, and whether the 

Emission Data Vehicle’s CO2 emission 

level is an appropriate surrogate for all 

vehicles in a test group at the time of 

certification, given that the certificate 

would be conditioned upon additional 

model level testing occurring during the 

year (see Section III.E.6) and that the 

surrogate CO2 emission values would be 

replaced with model-level emissions 

data from those tests. Comments should 

also address EPA’s desire to minimize 

the up-front pre-production testing 

burden and whether the proposed 

efficiencies would be balanced by the 

requirement to test all model types in 

the fleet by the conclusion of the model 

year in order to establish the fleet 

average CO2 levels. 

There are two standards that the 

manufacturer would be subject to, the 

fleet average standard and the in-use 

standard for the useful life of the 

vehicle. Compliance with the fleet 

average standard is based on 

production-weighted averaging of the 

test data that applies for each model. 

For each model, the in-use standard is 

set at 10% higher than the level used for 

that model in calculating the fleet 

average. The certificate would cover 

both of these standards, and the 

manufacturer would have to 

demonstrate compliance with both of 

these standards for purposes of 

receiving a certificate of conformity. The 

certification process for the in-use 

standard is discussed below in Section 

III.E.4. 

c. Certification Testing Protocols and 

Procedures 

To be consistent with CAFE, EPA 

proposes to combine the CO2 emissions 

results from the FTP and HFET tests 

using the same calculation method used 

to determine fuel economy for CAFE 

purposes. This approach is appropriate 

for CO2 because CO2 and fuel economy 

are so closely related. Other than the 

fact that fuel economy is calculated 

using a harmonic average and CO2 

emissions can be calculated using a 

conventional average, the calculation 

methods are very similar. The FTP CO2 
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data will be weighted at 55%, and the 

highway CO2 data at 45%, and then 

averaged to determine the combined 

number. See Section III.B.1 for more 

detailed information on CO2 test 

procedures, Section III.C.1 on Air 

Conditioning Emissions, and Section 

III.B.6 for N2O and CH4 test procedures. 

For the purposes of compliance with 

the fleet average and in-use standards, 

the emissions measured from each test 

vehicle will include hydrocarbons (HC) 

and carbon monoxide (CO), in addition 

to CO2. All three of these exhaust 

constituents are currently measured and 

used to determine the amount of fuel 

burned over a given test cycle using a 

‘‘carbon balance equation’’ defined in 

the regulations, and thus measurement 

of these is an integral part of current 

fuel economy testing. As explained in 

Section III.C, it is important to account 

for the total carbon content of the fuel. 

Therefore the carbon-related 

combustion products HC and CO must 

be included in the calculations along 

with CO2. CO emissions are adjusted by 

a coefficient that reflects the carbon 

weight fraction (CWF) of the CO 

molecule, and HC emissions are 

adjusted by a coefficient that reflects the 

CWF of the fuel being burned (the 

molecular weight approach doesn’t 

work since there are many different 

hydrocarbons being accounted for). 

Thus, EPA is proposing that the carbonrelated exhaust emissions of each test 

vehicle be calculated according to the 

following formula, where HC, CO, and 

CO2 are in units of grams per mile: 

Carbon-related exhaust emissions 

(grams/mile) = CWF*HC + 

1.571*CO + CO2 

As part of the current CAFE and Tier 

2 compliance programs, EPA selects a 

subset of vehicles for confirmatory 

testing at its National Vehicle and Fuel 

Emissions Laboratory. The purpose of 

confirmatory testing is to validate the 

manufacturer’s emissions and/or fuel 

economy data. Under this proposal, EPA 

would add CO2, N2O, and CH4 to the 

emissions measured in the course of 

Tier 2 and CAFE confirmatory testing. 

The emission values measured at the 

EPA laboratory would continue to stand 

as official, as under existing regulatory 

programs. 

As is the current practice with fuel 

economy testing, if during EPA’s 

confirmatory testing the EPA CO2 value 

differs from the manufacturer’s value by 

more than 3%, manufacturers could 

request a re-test. Also as with current 

practice, the results of the re-test would 

stand as official, even if they differ from 

the manufacturer value by more than 

3%. EPA is proposing to allow a re-test 

request based on a 3% or greater 

disparity since a manufacturer’s fleet 

average emissions level would be 

established on the basis of model level 

testing only (unlike Tier 2 for which a 

fixed bin standard structure provides 

the opportunity for a compliance 

buffer). EPA requests comment on 

whether the 3% value currently used 

during CAFE confirmatory testing is 

appropriate and should be retained 

under the proposed GHG program. 

4. Useful Life Compliance 

Section 202(a)(1) of the CAA requires 

emission standards to apply to vehicles 

throughout their statutory useful life, as 

further described in Section III.A. For 

emission programs that have fleet 

average standards, such as Tier 2 and 

the proposed CO2 standards, the useful 

life requirement applies to individual 

vehicles rather than to the fleet average 

standard. For example, in Tier 2 the 

useful life requirements apply to the 

individual emission standard levels or 

‘‘bins’’ that the vehicles are certified to, 

not the fleet average standard. For Tier 

2, the useful life requirement is 10 years 

or 120,000 miles with an optional 15 

year or 150,000 mile provision. For each 

model, the proposed CO2 standards inuse are the model specific levels used in 

calculating the fleet average, adjusted to 

be 10% higher. EPA is proposing the 

10% adjustment factor to provide some 

margin for production and test-to-test 

variability that could result in 

differences between initial model-level 

emission results used in calculating the 

fleet average and any subsequent in-use 

testing. EPA requests comment on 

whether a separate in-use standard is an 

appropriate means of addressing issues 

of variability and whether 10% is an 

appropriate adjustment. 

This in-use standard would apply for 

the same useful life period as in Tier 2. 

Section 202(i)(3)(D) of the CAA allows 

EPA to adopt useful life periods for 

light-duty vehicles and light-duty trucks 

which differ from those in section 

202(d). Similar to Tier 2, the useful life 

requirements would be applicable to the 

model-level CO2 certification values 

(similar to the Tier 2 bins), not to the 

fleet average standard. 

EPA believes that the useful life 

period established for criteria pollutants 

under Tier 2 is also appropriate for CO2. 

Data from EPA’s current in-use 

compliance test program indicate that 

CO2 emissions from current technology 

vehicles increase very little with age 

and in some cases may actually improve 

slightly. The stable CO2 levels are 

expected because unlike criteria 

pollutants, CO2 emissions in current 

technology vehicles are not controlled 

by after treatment systems that may fail 

with age. Rather, vehicle CO2 emission 

levels depend primarily on fundamental 

vehicle design characteristics that do 

not change over time. Therefore, 

vehicles designed for a given CO2 

emissions level would be expected to 

sustain the same emissions profile over 

their full useful life. 

The CAA requires emission standards 

to be applicable for the vehicle’s full 

useful life. Under Tier 2 and other 

vehicle emission standard programs, 

EPA requires manufacturers to 

demonstrate at the time of certification 

that the new vehicles being certified 

will continue to meet emission 

standards throughout their useful life. 

EPA allows manufacturers several 

options for predicting in-use 

deterioration, including full vehicle 

testing, bench-aging specific 

components, and application of a 

deterioration factor based on data and/ 

or engineering judgment. 

In the specific case of CO2, EPA does 

not currently anticipate notable 

deterioration and is therefore proposing 

that an assigned deterioration factor be 

applied at the time of certification. EPA 

is further proposing an additive 

assigned deterioration factor of zero, or 

a multiplicative factor of one. EPA 

anticipates that the deterioration factor 

would be updated from time to time, as 

new data regarding emissions 

deterioration for CO2 are obtained and 

analyzed. Additionally, EPA may 

consider technology-specific 

deterioration factors, should data 

indicate that certain CO2 control 

technologies deteriorate differently than 

others. 

During compliance plan discussions 

prior to the beginning of the 

certification process, EPA would 

explore with each manufacturer any 

new technologies that could warrant use 

of a different deterioration factor. 

Manufacturers would not be allowed to 

use the assigned deterioration factor but 

rather would be required to establish an 

appropriate factor for any vehicle model 

determined likely to experience 

increases in CO2 emissions over the 

vehicle’s useful life. If such an instance 

were to occur, EPA is also proposing to 

allow manufacturers to use the wholevehicle mileage accumulation method 

currently offered in EPA’s regulations. 

EPA requests comments on the 

proposal to allow manufacturers to use 

an EPA-assigned deterioration factor for 

CO2 useful life compliance, and to set 

that factor at zero (additive) or one 

(multiplicative). Particularly helpful 

would be data from in-use vehicles that 

demonstrate the rate of change in CO2 

emissions over a vehicle’s useful life, 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49563 

separated according to vehicle 

technology. 

N2O and CH4 emissions are directly 

affected by vehicle emission control 

systems. Any of the durability options 

offered under EPA’s current compliance 

program can be used to determine how 

emissions of N2O and CH4 change over 

time. 

a. Ensuring Useful Life Compliance 

The CAA requires a vehicle to comply 

with emission standards over its 

regulatory useful life and affords EPA 

broad authority for the implementation 

of this requirement. As such, EPA has 

authority to require a manufacturer to 

remedy any noncompliance issues. The 

remedy can range from the voluntary or 

mandatory recall of any noncompliant 

vehicles to the recalculation of a 

manufacturers fleet average emissions 

level. This provides manufacturers with 

a strong incentive to design and build 

complying vehicles. 

Currently, EPA regulations require 

manufacturers to conduct in-use testing 

as a condition of certification. 

Specifically, manufacturers must 

commit to later procure and test 

privately-owned vehicles that have been 

normally used and maintained. The 

vehicles are tested to determine the inuse levels of criteria pollutants when 

they are in their first and third years of 

service. This testing is referred to as the 

In-Use Verification Program (IUVP) 

testing, which was first implemented as 

part of EPA’s CAP 2000 certification 

program.174 The emissions data 

collected from IUVP serves several 

purposes. It provides EPA with annual 

real-world in-use data representing the 

majority of certified vehicles. EPA uses 

IUVP data to identify in-use problems, 

validate the accuracy of the certification 

program, verify the manufacturer’s 

durability processes, and support 

emission modeling efforts. 

Manufacturers are required to test low 

mileage and high mileage vehicles over 

the FTP and US06 test cycles. They are 

also required to provide evaporative 

emissions and on-board diagnostics 

(OBD) data. 

Manufacturers are required to provide 

data for all regulated criteria pollutants. 

Some manufacturers voluntarily submit 

CO2 data as part of IUVP. EPA is 

proposing that for IUVP testing, all 

manufacturers will provide emission 

data for CO2 and also for N2O and CH4. 

EPA is also proposing that 

manufacturers perform the highway test 

cycle as part of IUVP. Since the 

proposed CO2 standard reflects a 

combined value of FTP and highway 

174 64 FR 23906, May 4, 1999. 

results, it is necessary to include the 

highway emission test in IUVP to enable 

EPA to compare an in-use CO2 level 

with a vehicle’s in-use standard. EPA 

requests comments on adding the 

highway test cycle as part of the IUVP 

requirements. 

Another component of the CAP 2000 

certification program is the In-Use 

Confirmatory Program (IUCP). This is a 

manufacturer-conducted recall quality 

in-use test program that can be used as 

the basis for EPA to order an emission 

recall. In order to qualify for IUCP, there 

is a threshold of 1.30 times the 

certification emission standard and an 

additional requirement that at least 50% 

of the test vehicles for the test group fail 

for the same pollutant. EPA is proposing 

to exclude IUVP data for CO2, N2O, and 

CH4 emissions from the IUCP 

thresholds. At this time, EPA does not 

have sufficient data to determine if the 

existing thresholds are appropriate or 

even applicable to those emissions. 

Once EPA can gather more data from the 

IUVP program and from EPA’s internal 

surveillance program described below, 

EPA will reassess the need to exclude 

IUCP thresholds, and if warranted, 

propose a separate rulemaking 

establishing IUCP threshold criteria 

which may include CO2, N2O, and CH4 

emissions. EPA requests comment on 

the proposal to exclude CO2, N2O, and 

CH4 from the IUCP threshold. 

EPA has also administered its own inuse testing program for light-duty 

vehicles under authority of section 

207(c) of the CAA for more than 30 

years. In this program, EPA procures 

and tests representative privately owned 

vehicles to determine whether they are 

complying with emission standards. 

When testing indicates noncompliance, 

EPA works with the manufacturer to 

determine the cause of the problem and 

to conduct appropriate additional 

testing to determine its extent or the 

effectiveness of identified remedies. 

This program operates in conjunction 

with the IUVP program and other 

sources of information to provide a 

comprehensive picture of the 

compliance profile for the entire fleet 

and address compliance problems that 

are identified. EPA proposes to add CO2, 

N2O, and CH4 to the emissions 

measurements it collects during 

surveillance testing. 

b. In-Use Compliance Standard 

For Tier 2, the in-use standard and the 

certification standard are the same. Inuse compliance for an individual 

vehicle is determined by comparing the 

vehicle’s in-use emission results with 

the emission standard levels or ‘‘bin’’ to 

which the vehicle is certified rather 

than to the Tier 2 fleet average standard 

for the manufacturer. This is because as 

part of a fleet average standard, 

individual vehicles can be certified to 

various emission standard levels, which 

could be higher or lower than the fleet 

average standard. Thus, comparing an 

individual vehicle to the fleet average, 

where that vehicle was certified to an 

emission level that could be different 

than the fleet average level, would be 

inappropriate. 

This would also be true for the 

proposed CO2 fleet average standard. 

Therefore, to ensure that an individual 

vehicle complies with the proposed CO2 

standards in-use, it is necessary to 

compare the vehicle’s in-use CO2 

emission result with the appropriate 

model-level certification CO2 level used 

in determining the manufacturer’s fleet 

average result. 

There is a fundamental difference 

between the proposed CO2 standards 

and Tier 2 standards. For Tier 2, the 

certification standard is one of eight 

different emission levels, or ‘‘bins,’’ 

whereas for the proposed CO2 fleet 

average standard, the certification 

standard is the model-level certification 

CO2 result. The Tier 2 fleet average 

standard is calculated using the ‘‘bin’’ 

emission level or standard, not the 

actual certification emission level of the 

certification test vehicle. So no matter 

how low a manufacturer’s actual 

certification emission results are, the 

fleet average is still calculated based on 

the ‘‘bin’’ level rather than the lower 

certification result. In contrast, EPA is 

proposing that the CO2 fleet average 

standard would be calculated using the 

actual vehicle model-level CO2 values 

from the certification test vehicles. With 

a known certification emission 

standard, such as the Tier 2 ‘‘bins,’’ 

manufacturers typically attempt to overcomply with the standard to give 

themselves some cushion for potentially 

higher in-use testing results due to 

emissions performance deterioration 

and/or variability that could result in 

higher emission levels during 

subsequent in-use testing. For our 

proposed CO2 standards, the 

certification standard is the actual 

certification vehicle test result, thus 

manufacturers cannot over comply since 

the certification test vehicle result will 

always be the value used in determining 

the CO2 fleet average. If the 

manufacturer attempted to design the 

vehicle to achieve a lower CO2 value, 

similar to Tier 2 for in-use purposes, the 

new lower CO2 value would simply 

become the new certification standard. 

The CO2 fleet average standard is 

based on the performance of preproduction technology that is 
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49564 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

representative of the point of 

production, and while there is expected 

to be limited if any deterioration in 

effectiveness for any vehicle during the 

useful life, the fleet average standard 

does not take into account the test to 

test variability or production variability 

that can affect in-use levels. Therefore, 

EPA believes that unlike Tier 2, it is 

necessary to have a different in-use 

standard for CO2 to account for these 

variabilities. EPA is proposing to set the 

in-use standard at 10% higher than the 

appropriate model-level certification 

CO2 level used in determining the 

manufacturer’s fleet average result. 

As described above, manufacturers 

typically design their vehicles to emit at 

emission levels considerably below the 

standards. This intentional difference 

between the actual emission level and 

the emission standard is referred to as 

‘‘certification margin,’’ since it is 

typically the difference between the 

certification emission level and the 

emission standard. The certification 

margin can provide manufacturers with 

some protection from exceeding 

emission standards in-use, since the inuse standards are typically the same as 

the certification standards. For Tier 2, 

the certification margin is the delta 

between the specific emission standard 

level, or ‘‘bin,’’ to which the vehicle is 

certified, and the vehicle’s certification 

emission level. 

Since the level of the fleet average 

standard does not reflect this kind of 

variability, EPA believes it is 

appropriate to set an in-use standard 

that provides manufacturers with an inuse compliance factor of 10% that will 

act as a surrogate for a certification 

margin. The factor would only be 

applicable to CO2 emissions, and would 

be applied to the model-level test results 

that are used to establish the modellevel in-use standard. 

If the in-use emission result for the 

vehicle exceeds the model-level CO2 

certification result multiplied by the inuse compliance factor of 10%, then the 

vehicle would have exceeded the in-use 

emission standard. The in-use 

compliance factor would apply to all inuse compliance testing including IUVP, 

selective enforcement audits, and EPA’s 

internal test program. 

The intent of the separate in-use 

standard, based on a 10% compliance 

factor adjustment, is to provide a 

reasonable margin such that vehicles are 

not automatically deemed as exceeding 

standards simply because of normal 

variability in test results. EPA has some 

concerns however that this in-use 

compliance factor could be perceived as 

providing manufacturers with the 

ability to design their fleets to generate 

CO2 emissions up to 10% higher than 

the actual values they use to certify and 

to calculate the year end fleet average 

value that determines compliance with 

the fleet average standard. This concern 

provides additional rationale for 

requiring FTP and HFET IUVP data for 

CO2 emissions to ensure that in-use 

values are not regularly 10% higher 

than the values used in the fleet average 

calculation. If in the course of reviewing 

a manufacturer’s IUVP data it becomes 

apparent that a manufacturer’s CO2 

results are consistently higher than the 

values used for certification, EPA would 

discuss the matter with the 

manufacturer and consider possible 

resolutions such as changes to ensure 

that the emissions test data more 

accurately reflects the emissions level of 

vehicles at the time of production, 

increased EPA confirmatory testing, and 

other similar measures. 

EPA selected a value of 10% for the 

in-use standard based on a review of 

EPA’s fuel economy labeling and CAFE 

confirmatory test results for the past 

several vehicle model years. The EPA 

data indicate that it is common for test 

variability to range between three to six 

percent and only on rare occasions to 

exceed 10%. EPA believes that a value 

of 10% should be sufficient to account 

for testing variability and any 

production variability that a 

manufacturer may encounter. EPA 

considered both higher and lower 

values. The Tier 2 fleet as a whole, for 

example, has a certification margin 

approaching 50%.175 However, there are 

some fundamental differences between 

CO2 emissions and other criteria 

pollutants in the magnitude of the 

pollutants. Tier 2 NMOG and NOX 

emission standards are hundredths of a 

gram per mile (e.g., 0.07 g/mi NOX & 

0.09 g/mi NMOG), whereas the CO2 

standards are four orders of magnitude 

greater (e.g., 250 g/mi). Thus EPA does 

not believe it is appropriate to consider 

a value on the order of 50 percent. In 

addition, little deterioration in 

emissions control is expected in-use. 

The adjustment factor addresses only 

one element of what is usually built into 

a compliance margin. 

EPA requests comments regarding a 

proposed in-use standard that uses an 

in-use compliance factor. Specifically, is 

a factor the best way to address the 

technical and other feasibility of the inuse standard; is 10% the appropriate 

factor; can EPA expect variability to 

decrease as manufacturing experience 

175 See pages 39–41 of EPA’s Vehicle and Engine 

Compliance Activities 2007 Progress Report (EPA– 

420–R–08–011) published in October 2008. This 

document is available electronically at http:// 

epa.gov/otaq/about/420r08011.pdf. 

increases, in which case would it be 

appropriate for the in-use compliance 

factor of 10% to decrease over time? 

EPA especially requests any data to 

support such comments. 

5. Credit Program Implementation 

As described in Section III.E.2 above, 

for each manufacturer’s model year 

production, EPA is proposing that the 

manufacturer would average the CO2 

emissions within each of the two 

averaging sets (passenger cars and 

trucks) and compare that with its 

respective fleet average CO2 standards 

(which in turn would have been 

determined from the appropriate 

footprint curve applicable to that model 

year). In addition to this withincompany averaging, EPA is proposing 

that when a manufacturer’s fleet average 

CO2 emissions of vehicles produced in 

an averaging set over-complies 

compared to the applicable fleet average 

standard, the manufacturer could 

generate credits that it could save for 

later use (banking) or could transfer to 

another manufacturer (trading). Section 

III.C discusses opportunities that EPA is 

proposing for manufacturers to earn 

additional credits, beyond those simply 

calculated by ‘‘over-achieving’’ their 

applicable standard. Implementation of 

the credit program generally involves 

two steps: calculation of the credit 

amount and reporting the amount and 

the associated data and calculations to 

EPA. 

Of the various credit programs being 

proposed by EPA, there are two broad 

types. One type of credit directly lowers 

a manufacturer’s actual fleet average by 

virtue of being applied to the 

methodology for calculating the fleet 

average emissions. Examples of this 

type of credit include the credits 

available for alternative fuel vehicles 

and for advanced technology vehicles. 

The second type of credit is 

independent of the calculation of a 

manufacturer’s fleet average. Rather 

than giving credit by lowering a 

manufacturer’s fleet average via a credit 

mechanism, these credits (in 

megagrams) are calculated separately 

and are simply added to the 

manufacturer’s overall ‘‘bank’’ of credits 

(or debits). Using a fictional example, 

the remainder of this section will step 

through the different types of credits 

and show where and how they are 

calculated and how they impact a 

manufacturer’s available credits. 

a. Basic Credits for a Fleet With Average 

CO2 Emissions Below the Standard 

Basic credits are earned by doing 

better than the applicable standard. 

Manufacturers calculate their standards 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49565 

(separate standards are calculated for 

cars and trucks) using the footprintbased equations described in Section 

III.B. A manufacturer’s actual end-ofyear fleet average CO2 is calculated 

similarly to the way in which CAFE 

values are currently calculated; in fact, 

the regulations are essentially identical. 

The current CAFE calculation methods 

are in 40 CFR Part 600. EPA is 

proposing to amend key subparts and 

sections of Part 600 to require that fleet 

average CO2 be calculated in a manner 

parallel to the way CAFE values are 

calculated. First manufacturers would 

determine a CO2-equivalent value for 

each model type. The CO2-equivalent 

value is a summation of the carboncontaining constituents of the exhaust 

emissions, with each weighted by a 

coefficient that reflects the carbon 

weight fraction of that constituent. For 

gasoline and diesel vehicles this simply 

involves measurement of total 

hydrocarbons and carbon monoxide in 

addition to CO2, but becomes somewhat 

more complex for alternative fuel 

vehicles due to the different nature of 

their exhaust emissions. For example, 

for ethanol-fueled vehicles, the emission 

tests must measure ethanol, methanol, 

formaldehyde, and acetaldehyde in 

addition to CO2. However, all these 

measurements are necessary to 

determine fuel economy and thus no 

new testing or data collection would be 

required. Second, manufacturers would 

calculate a fleet average by weighting 

the CO2-equivalent value for each model 

type by the production of that model 

type, as they currently do for the CAFE 

program. Again, this would be done 

separately for cars and trucks. Finally, 

the manufacturer would compare the 

calculated standard with the average 

that is actually achieved to determine 

the credits (or debits). Both the 

determination of the applicable 

standard and the actual fleet average 

would be done after the model year is 

complete and using final model year 

production data. 

Consider a basic example where 

Manufacturer ‘‘A’’ has calculated a car 

standard of 300 grams/mile and a fleet 

average of 290 grams/mile (Figure 

III.E.5–1). Further assume that the 

manufacturer produced 500,000 cars. 

The credit is calculated by taking the 

difference between the standard and the 

fleet average (300–290=10) and 

multiplying it by the production of 

500,000. This result is then multiplied 

by the lifetime vehicle miles travelled 

(for cars this is 190,971 miles), then 

finally divided by 1,000,000 to convert 

from grams to total megagrams. The 

result is the number of CO2 megagrams 

of credit (or deficit, if the manufacturer 

was not able to comply with the fleet 

average standard) generated by the 

manufacturer’s car fleet. In this 

example, the result is 954,855 

megagrams. 

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49566 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

b. Advanced Technology Credits 

Advanced technology credits directly 

impact a manufacturer’s fleet average, 

thus increasing the amount of credits 

they earn (or reducing the amount of 

debits that would otherwise accrue). To 

earn these credits, manufacturers that 

produce electric vehicles, plug-in 

hybrid electric vehicles, or fuel cell 

electric vehicles would include these 

vehicles in the fleet average calculation 

with their model type emission values 

(0 g/m for electric vehicles and fuel cell 

electric vehicles, and a measured CO2 

value for plug-in hybrid electric 

vehicles), but would apply the proposed 

multiplier of 2.0 to the production 

volume of each of these vehicles. This 

approach would thus enhance the 

impact that each of these low-CO2 

advanced technology vehicles has on 

the manufacturer’s fleet average. 

EPA is proposing to limit availability 

of advanced technology credits to the 

technologies noted above, with the 

additional limitation that the vehicles 

must be certified to Tier 2 Bin 5 

emission standards or cleaner (this 

obviously applies primarily to plug-in 

hybrid electric vehicles). EPA is 

proposing to use the following 

definitions to determine which vehicles 
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are eligible for the advanced technology 

credits: 

• Electric vehicle means a motor 

vehicle that is powered solely by an 

electric motor drawing current from a 

rechargeable energy storage system, 

such as from storage batteries or other 

portable electrical energy storage 

devices, including hydrogen fuel cells, 

provided that: 

Æ (1) Recharge energy must be drawn 

from a source off the vehicle, such as 

residential electric service; and 

Æ (2) The vehicle must be certified to 

the emission standards of Bin #1 of 

Table S04–1 in paragraph (c)(6) of 

§ 86.1811. 

• Fuel cell electric vehicle means a 

motor vehicle propelled solely by an 

electric motor where energy for the 

motor is supplied by a fuel cell.

• Fuel cell means an electrochemical 

cell that produces electricity via the 

reaction of a consumable fuel on the 

anode with an oxidant on the cathode 

in the presence of an electrolyte. 

• Plug-in hybrid electric vehicle 

(PHEV) means a hybrid electric vehicle 

that: (1) Has the capability to charge the 

battery from an off-vehicle electric 

source, such that the off-vehicle source 

cannot be connected to the vehicle 

while the vehicle is in motion, and (2) 

has an equivalent all-electric range of no 

less than 10 miles. 

With some simplifying assumptions, 

assume that 25,000 of Manufacturer A’s 

fleet are now plug-in hybrid electric 

vehicles with CO2 emissions of 100 

g/mi, and the remaining 475,000 are 

conventional technology vehicles with 

average CO2 emissions of 290 grams/ 

mile. By applying the factor of 2.0 to the 

electric vehicle production numbers in 

the appropriate places in the fleet 

average calculation formula 

Manufacturer A now has more than 2.6 

million credits (Figure III.E.5–2). 

Without the use of the multiplier 

Manufacturer A’s fleet average would be 

281 instead of 272, which would 

generate about 1.8 million credits. 

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49568 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

c. Flexible-Fuel Vehicle Credits 

As noted in Section III.C, treatment of 

flexible-fuel vehicle (FFV) credits differs 

between 2012 to 2015 and 2016 and 

later. For the 2012 through 2015 model 

years the FFV credits will be calculated 

as they are in the CAFE program for the 

same model years, except that formulae 

in the regulations would be modified as 

needed to do the calculations in terms 

of grams per mile of CO2 rather than 

miles per gallon. Like the advanced 

technology vehicle credits, these credits 

are integral to the fleet average 

calculation, but rather than crediting the 

vehicles with an artificially inflated 

quantity as in the advanced technology 

credit program described above, the FFV 

credit program allows the vehicles to be 

represented by artificially reduced 

emissions. To use this credit program, 

the CO2 emissions of FFVs will be 

represented by the average of two 

things: the CO2 emissions while 

operating on gasoline, and the CO2 

emissions operating on the alternative 

fuel multiplied by 0.15. 

For example, Manufacturer A now 

makes 30,000 FFVs with CO2 emissions 

of 280 g/mi using gasoline and 260 

g/mi using ethanol. The CO2 emissions 

that would represent the FFVs in the 

fleet average calculation would be 

calculated as follows: 

FFV emissions = (280 + 260×0.15) ÷ 2 

= 160 g/mi 

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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49569 

Including these FFVs with the III.E.5–3, further reduces the fleet the manufacturer’s credits to about 4.2 

applicable credit in Manufacturer A’s average to 256 grams/mile and increases million megagrams. 

fleet average, as shown below in Figure 

In the 2016 and later model years the based upon the actual use of the used negligibly, and the CO2 value that 

calculation of FFV emissions would be alternative fuel and on actual CO2 would apply to an FFV by default 

much the same except that the emissions while operating on that fuel. would be the value determined for 

determination of the CO2 value to EPA’s default assumption in the operation on conventional fuel. 

represent an FFV model type would be regulations is that the alternative fuel is However, if the manufacturer believes 
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49570 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

that the alternative fuel is used in realworld driving and that accounting for 

this use could improve the fleet average, 

the manufacturer would have two 

options. First, the regulations would 

allow a manufacturer to request that 

EPA determine an appropriate 

weighting value for an alternative fuel to 

reflect the degree of use of that fuel in 

FFVs relative to real-world use of the 

conventional fuel. Section III.C 

describes how EPA might make this 

determination. Any value determined 

by EPA would be published via 

guidance letter to manufacturers, and 

that weighting value would be available 

for all manufacturers to use for that fuel. 

A second option proposed in the 

regulations would allow a manufacturer 

to determine the degree of alternative 

fuel use for their own vehicle(s), using 

a variety of potential methods. Both the 

method and the use of the final results 

would have to be approved by EPA 

before their use would be allowed. In 

either case, whether EPA supplies the 

weighting factors or the manufacturer 

determines them, the CO2 emissions of 

an FFV in 2016 and later would be as 

follows (assuming non-zero use of the 

alternative fuel): 

(W1×CO2conv)+(W2×CO2alt), 

Where, 

W1 and W2 are the proportion of miles 

driven using conventional fuel and 

alternative fuel, respectively, CO2conv is the 

CO2 value while using conventional fuel, and 

CO2alt is the CO2 value while using the 

alternative fuel. 

d. Dedicated Alternative Fuel Vehicle 

Credits 

Like the FFV credit program 

described above, these credits would be 

treated differently in the first years of 

the program than in the 2016 and later 

model years. In fact, these credits are 

essentially identical to the FFV credits 

except for two things: (1) There is no 

need to average CO2 values for gasoline 

and alternative fuel, and (2) in 2016 and 

later there is no demonstration needed 

to get a benefit from the alternative fuel. 

The CO2 values are essentially 

determined the same way they are for 

FFVs operating on the alternative fuel. 

For the 2012 through 2015 model years 

the CO2 test results are multiplied by 

the credit adjustment factor of 0.15, and 

the result is production-weighted in the 

fleet average calculation. For example, 

assume that Manufacturer A now 

produces 20,000 dedicated CNG 

vehicles with CO2 emissions of 220 

grams/mile, in addition to the FFVs and 

PHEVs already included in their fleet 

(Figure III.E.5–4). Prior to the 2016 

model year the CO2 emissions 

representing these CNG vehicles would 

be 33 grams/mile (220 × 0.15). 

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BILLING CODE 4910–59–C 

The calculation for 2016 and later 

would be exactly the same except the 

0.15 credit adjustment factor would be 

removed from the equation, and the 

CNG vehicles would simply be 

production-weighted in the equation 

using their actual emissions value of 

220 grams/mile instead of the 

‘‘credited’’ value of 33 grams/mile. 

e. Air Conditioning Leakage Credits 

Unlike the credit programs described 

above, air conditioning-related credits 

do not affect the overall calculation of 

the fleet average. Whether a 

manufacturer generates zero air 

conditioning credits or many, the 

calculated fleet average remains the 

same. Air conditioning credits are 

calculated and added to any credits (or 

deficit) that results from the fleet 

average calculation. Thus, these credits 

can increase a manufacturer’s credit 

balance or offset a deficit, but their 

calculation is external to the fleet 

average calculation. As noted in Section 

III.C, manufacturers could generate 

credits for reducing the leakage of 

refrigerant from their air conditioning 

systems. To do this the manufacturer 

would identify an air conditioning 

system improvement, indicate that they 
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49572 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

intend to use the improvement to 

generate credits, and then calculate an 

annual leakage rate (grams/year) for that 

system based on the method defined by 

the proposed regulations. Air 

conditioning credits would be 

determined separately for cars and 

trucks using the car and truck-specific 

equations described in Section III.C. 

In order to put these credits on the 

same basis as the basic and other credits 

describe above, the air conditioning 

leakage credits would need to be 

calculated separately for cars and 

trucks. Thus, the resulting grams per 

mile credit determined from the 

appropriate car or truck equation would 

be multiplied by the lifetime VMT 

(190,971 for cars; 221,199 for trucks), 

and then divided by 1,000,000 to get the 

total megagrams of CO2 credits 

generated by the improved air 

conditioning system. Although the 

calculations are done separately for cars 

and trucks, the total megagrams would 

be summed and then added to the 

overall credit balance maintained by the 

manufacturer. 

For example, assume that 

Manufacturer A has improved an air 

conditioning system that is installed in 

250,000 cars and that the calculated 

leakage rate is 12 grams/year. Assume 

that the manufacturer has also 

implemented a new refrigerant with a 

Global Warming Potential of 850. In this 

case the credit per air conditioning unit, 

rounded to the nearest gram per mile 

would be: 

[13.8 × [1—(12/16.6 × 850/1430)] = 7.9 

g/mi. 

Total megagrams of credits would 

then be: 

[ 7.9 × 250,000 × 190971 ] ÷ 1,000,000 

= 377,168 Mg. 

These credits would be added directly 

to a manufacturer’s total balance; thus 

in this example Manufacturer A would 

now have, after consideration of all the 

above credits, a total of 5,437,900 

Megagrams of credits. 

f. Air Conditioning Efficiency Credits 

As noted in Section III.C.1.b, 

manufacturers could earn credits for 

improvements in air conditioning 

efficiency that reduce the impact of the 

air conditioning system on fuel 

consumption. These credits are similar 

to the air conditioning leakage credits 

described above, in that these credits are 

determined independently from the 

manufacturer’s fleet average calculation, 

and the resulting credits are added to 

the manufacturer’s overall balance for 

the respective model year. Like the air 

conditioning leakage credits, these 

credits can increase a manufacturer’s 

credit balance or offset a deficit, but 

their calculation is external to the fleet 

average calculation. 

In order to put these credits on the 

same basis as the basic and other credits 

describe above, the air conditioning 

leakage credits would need to be 

calculated separately for cars and 

trucks. Thus, the resulting grams per 

mile credit determined in the above 

equation would be multiplied by the 

lifetime VMT (190,971 for cars; 221,199 

for trucks), and then divided by 

1,000,000 to get the total megagrams of 

CO2 credits generated by the improved 

air conditioning system. Although the 

calculations are done separately for cars 

and trucks, the total megagrams can be 

summed and then added to the overall 

credit balance maintained by the 

manufacturer. 

As described in Section III.C, 

manufacturers would determine their 

credit based on selections from a menu 

of technologies, each of which provides 

a gram per mile credit amount. The 

credits would be summed for all the 

technologies implemented by the 

manufacturer, but could not exceed 5.7 

grams per mile. Once this is done, the 

calculation is a straightforward 

translation of a gram per mile credit to 

total car or truck megagrams, using the 

same methodology described above. For 

example, if Manufacturer A implements 

enough technologies to get the 

maximum 5.7 grams per mile for an air 

conditioning system that sells 250,000 

units in cars, the calculation of total 

credits would be as follows: 

[5.7 × 250,000 × 190971] ÷ 1,000,000 = 

272,134 Mg. 

These credits would be added directly 

to a manufacturer’s total balance; thus 

in this example Manufacturer A would 

now have, after consideration of all the 

above credits, a total of 5,710,034 

Megagrams of credits. 

g. Off-Cycle Technology Credits 

As described in Section III.C, these 

credits would be available for certain 

technologies that achieve real-world 

CO2 reductions that aren’t adequately 

captured on the city or highway test 

cycles used to determine compliance 

with the fleet average standards. Like 

the air conditioning credits, these 

credits are independent of the fleet 

average calculation. Section III.C.4 

describes two options for generating 

these credits: either using EPA’s 5-cycle 

fuel economy labeling methodology, or 

if that method fails to capture the CO2-

reducing impact of the technology, the 

manufacturer could propose and use, 

with EPA approval, a different 

analytical approach to determining the 

credit amount. Like the air conditioning 

credits above, these credits would have 

to be determined separately for cars and 

trucks because of the differing lifetime 

mileage assumptions between cars and 

trucks. 

Using the 5-cycle approach would be 

relatively straightforward, and because 

the 5-cycle formulae account for 

nationwide variations in driving 

conditions, no additional adjustments to 

the test results would be necessary. The 

manufacturer would simply calculate a 

5-cycle CO2 value with the technology 

installed and operating and compare it 

with a 5-cycle CO2 value determined 

without the technology installed and/or 

operating. Existing regulations describe 

how to calculate 5-cycle fuel economy 

values, and the proposed regulations 

contain provisions that describe how to 

calculate 5-cycle CO2 values. The 

manufacturer would have to design a 

test program that accounts for vehicle 

differences if the technology is installed 

in different vehicle types, and enough 

data would have to be collected to 

address data uncertainty issues. A 

description of such a test program and 

the results would be submitted to EPA 

for approval. 

As noted in Section III.C.4, a 

manufacturer-developed testing, data 

collection and analysis program would 

require some additional EPA approval 

and oversight. Once the demonstration 

of the CO2 reduction of an off-cycle 

technology is complete, however, and 

the resulting value accounts for 

variations in driving, climate and other 

conditions across the country, the two 

approaches are treated fundamentally 

the same way and in a way that parallels 

the approach for determining the air 

conditioning credits described above. 

Once a gram per mile value is approved 

by the EPA, the manufacturer would 

determine the total credit value by 

multiplying the gram per mile per 

vehicle credit by the volume of vehicles 

with that technology and approved for 

use of the credit. This would then be 

multiplied by the lifetime vehicle miles 

for cars or trucks, whichever applies, 

and divided by 1,000,000 to obtain total 

Megagrams of CO2 credits. These credits 

would then be added to the 

manufacturer’s total balance for the 

given model year. Just like the above air 

conditioning case, an off-cycle 

technology that is demonstrated to 

achieve an average CO2 reduction of 4 

grams/mile and that is installed in 

175,000 cars would generate credits as 

follows: 

[4 × 175,000 × 190971] ÷ 1,000,000 = 

133,680 Mg. 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49573 

h. End-of-Year Reporting 

In general, implementation of the 

averaging, banking, and trading (ABT) 

program, including the calculation of 

credits and deficits, would be 

accomplished via existing reporting 

mechanisms. EPA’s existing regulations 

define how manufacturers calculate 

fleet average miles per gallon for CAFE 

compliance purposes, and EPA is 

proposing to modify these regulations to 

also require the parallel calculation of 

fleet average CO2 levels for car and light 

truck compliance categories. These 

regulations already require an end-ofyear report for each model year, 

submitted to EPA, which details the test 

results and calculations that determine 

each manufacturer’s CAFE levels. EPA 

is proposing to require that this report 

also include fleet average CO2 levels. In 

addition to requiring reporting of the 

actual fleet average achieved, this endof-year report would also contain the 

calculations and data determining the 

manufacturer’s applicable fleet average 

standard for that model year. As under 

the existing Tier 2 program, the report 

would be required to contain the fleet 

average standard, all values required to 

calculate the fleet average standard, the 

actual fleet average CO2 that was 

achieved, all values required to 

calculate the actual fleet average, the 

number of credits generated or debits 

incurred, all the values required to 

calculate the credits or debits, and the 

resulting balance of credits or debits. 

Because of the multitude of credit 

programs that are available, the end-ofyear report will be required to have 

more data and a more defined and 

specific structure than the CAFE end– 

of-year report does today. Although 

requiring ‘‘all the data required’’ to 

calculate a given value should be 

inclusive, the proposed report would 

contain some requirements specific to 

certain types of credits. 

For advanced technology credits that 

apply to vehicles like electric vehicles 

and plug-in hybrid electric vehicles, 

manufacturers would be required to 

identify the number and type of these 

vehicles and the effect of these credits 

on their fleet average. The same would 

be true for credits due to flexible-fuel 

and alternative-fuel vehicles, although 

for 2016 and later flexible-fuel credits 

manufacturers would also have to 

provide a demonstration of the actual 

use of the alternative fuel in-use and the 

resulting calculations of CO2 values for 

such vehicles. For air conditioning 

leakage credits manufacturers would 

have to include a summary of their use 

of such credits that would include 

which air conditioning systems were 

subject to such credits, information 

regarding the vehicle models which 

were equipped with credit-earning air 

conditioning systems, the production 

volume of these air conditioning 

systems, the leakage score of each air 

conditioning system generating credits, 

and the resulting calculation of leakage 

credits. Air conditioning efficiency 

reporting will be somewhat more 

complicated given the phase-in of the 

efficiency test, and reporting would 

have to detail compliance with the 

phase-in as well as the test results and 

the resulting efficiency credits 

generated. Similar reporting 

requirements would also apply to the 

variety of possible off-cycle credit 

options, where manufacturers would 

have to report the applicable 

technology, the amount of credit per 

unit, the production volume of the 

technology, and the total credits from 

that technology. 

Although it is the final end-of-year 

report, when final production numbers 

are known, that will determine the 

degree of compliance and the actual 

values of any credits being generated by 

manufacturers, EPA is also proposing 

that manufacturers be prepared to 

discuss their compliance approach and 

their potential use of the variety of 

credit options in pre-certification 

meetings that EPA routinely has with 

manufacturers. In addition, and in 

conjunction with a pre-model year 

report required under the CAFE 

program, the manufacturer would be 

required to submit projections of all of 

the elements described above. 

Finally, to the extent that there are 

any credit transactions, the 

manufacturer would have to detail in 

the end-of-year report documentation on 

all credit transactions that the 

manufacturer has engaged in. 

Information for each transaction would 

include: The name of the credit 

provider, the name of the credit 

recipient, the date the transfer occurred, 

the quantity of credits transferred, and 

the model year in which the credits 

were earned. Failure by the 

manufacturer to submit the annual 

report in the specified time period 

would be considered to be a violation of 

section 203(a)(1) of the Clean Air Act. 

6. Enforcement 

As discussed above in Section III.E.5 

under the proposed program, 

manufacturers would report to EPA 

their fleet average standard for a given 

model year (reporting separately for 

each of the car and truck averaging sets), 

the credits or deficits generated in the 

current year, the balance of credit 

balances or deficits (taking into account 

banked credits, deficit carry-forward, 

etc. see Section III.E.5), and whether 

they were in compliance with the fleet 

average standard under the terms of the 

regulations. EPA would review the 

annual reports, figures, and calculations 

submitted by the manufacturer to 

determine any nonconformance. EPA 

requests comments on the above 

approach for monitoring and 

enforcement of the fleet average 

standard. 

Each certificate, required prior to 

introduction into commerce, would be 

conditioned upon the manufacturer 

attaining the CO2 fleet average standard. 

If a manufacturer failed to meet this 

condition and had not generated or 

purchased enough credits to cover the 

fleet average exceedance following the 

three year deficit carry-forward (Section 

III.B.4, then EPA would review the 

manufacturer’s sales for the most recent 

model year and designate which 

vehicles caused the fleet average 

standard to be exceeded. EPA would 

designate as nonconforming those 

vehicles with the highest emission 

values first, continuing until a number 

of vehicles equal to the calculated 

number of non-complying vehicles as 

determined above is reached and those 

vehicles would be considered to be not 

covered by the certificates of conformity 

covering those model types. In a test 

group where only a portion of vehicles 

would be deemed nonconforming, EPA 

would determine the actual 

nonconforming vehicles by counting 

backwards from the last vehicle sold in 

that model type. A manufacturer would 

be subject to penalties and injunctive 

orders on an individual vehicle basis for 

sale of vehicles not covered by a 

certificate. This is the same general 

mechanism used for the National LEV 

and Tier 2 corporate average standards, 

except that these programs operate 

slightly differently in that the noncompliant vehicles would be designated 

not in the most recent model year, but 

in the model year in which the deficit 

originated. EPA requests comment on 

which approach is most appropriate; the 

Tier 2 approach of penalizing vehicles 

from the year in which the deficit was 

generated, or the proposed approach 

that would penalize vehicles from the 

year in which the manufacturer failed to 

make up the deficit as required. 

Section 205 of the CAA authorizes 

EPA to assess penalties of up to $37,500 

per vehicle for violations of the 

requirements or prohibitions of this 

proposed rule.176 This section of the 

176 42 U.S.C. 7524(a), Civil Monetary Penalty 

Inflation Adjustment, 69 FR 7121 (Feb. 13, 2004) 

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CAA provides that the agency shall take 

the following penalty factors into 

consideration in determining the 

appropriate penalty for any specific 

case: The gravity of the violation, the 

economic benefit or savings (if any) 

resulting from the violation, the size of 

the violator’s business, the violator’s 

history of compliance with this title, 

action taken to remedy the violation, the 

effect of the penalty on the violator’s 

ability to continue in business, and such 

other matters as justice may require. 

EPA recognizes that it may be 

appropriate, should a manufacturer fail 

to comply with the NHTSA fuel 

economy standards as well as the CO2 

standard proposed today in a case 

arising out of the same facts and 

circumstances, to take into account the 

civil penalties that NHTSA has assessed 

for violations of the CAFE standards 

when determining the appropriate 

penalty amount for violations of the CO2 

emissions standards. This approach is 

consistent with EPA’s broad discretion 

to consider ‘‘such other matters as 

justice may require,’’ and will allow 

EPA to exercise its discretion to prevent 

injustice and ensure that penalties for 

violations of the CO2 rule are assessed 

in a fair and reasonable manner. 

The statutory penalty factor that 

allows EPA to consider ‘‘such other 

matters as justice may require’’ vests 

EPA with broad discretion to reduce the 

penalty when other adjustment factors 

prove insufficient or inappropriate to 

achieve justice.177 The underlying 

principle of this penalty factor is to 

operate as a safety mechanism when 

necessary to prevent injustice.178 

In other environmental statutes, 

Congress has specifically required EPA 

to consider penalties assessed by other 

government agencies where violations 

arise from the same set of facts. For 

instance, section 311(b)(8) of the Clean 

Water Act, 33 U.S.C. 1321(b)(8) 

authorizes EPA to consider any other 

penalty for the same incident when 

determining the appropriate Clean 

Water Act penalty. Likewise, section 

113(e) of the CAA authorizes EPA to 

consider ‘‘payment by the violator of 

penalties previously assessed for the 

same violation’’ when assessing 

penalties for certain violations of Title 

I of the Act. 

7. Prohibited Acts in the CAA 

Section 203 of the Clean Air Act 

describes acts that are prohibited by 

and Civil Monetary Penalty Inflation Adjustment 

Rule, 73 FR 75340 (Dec. 11, 2008). 

177 In re Spang & Co., 6 E.A.D. 226, 249 (EAB 

1995). 

178 B.J. Carney Industries, 7 E.A.D. 171, 232, n. 82 

(EAB 1997). 

law. This section and associated 

regulations apply equally to the 

greenhouse standards proposed today as 

to any other regulated pollutant. 

8. Other Certification Issues 

a. Carryover/Carry Across Certification 

Test Data 

EPA’s certification program for 

vehicles allows manufacturers to carry 

certification test data over and across 

certification testing from one model year 

to the next, when no significant changes 

to models are made. EPA expects that 

this policy could also apply to CO2, N2O 

and CH4 certification test data. A 

manufacturer may also be eligible to use 

carryover and carry across data to 

demonstrate CO2 fleet average 

compliance if they had done so for 

CAFE purposes. 

b. Compliance Fees 

The CAA allows EPA to collect fees 

to cover the costs of issuing certificates 

of conformity for the classes of vehicles 

and engines covered by this proposal. 

On May 11, 2004, EPA updated its fees 

regulation based on a study of the costs 

associated with its motor vehicle and 

engine compliance program (69 FR 

51402). At the time that cost study was 

conducted the current rulemaking was 

not considered. 

At this time the extent of any added 

costs to EPA as a result of this proposal 

is not known. EPA will assess its 

compliance testing and other activities 

associated with the proposed rule and 

may amend its fees regulations in the 

future to include any warranted new 

costs. 

c. Small Entity Deferment 

EPA is proposing to defer CO2 

standards for certain small entities, and 

these entities (necessarily) would not be 

subject to the certification requirements 

of this proposal. 

As discussed in Section III.B.7, 

businesses meeting the Small Business 

Administration (SBA) criterion of a 

small business as described in 13 CFR 

121.201 would not be subject to the 

proposed GHG requirements, pending 

future regulatory action. EPA is 

proposing that such entities submit a 

declaration to EPA containing a detailed 

written description of how that 

manufacturer qualifies as a small entity 

under the provisions of 13 CFR 121.201 

in order to ensure EPA is aware of the 

deferred companies. This declaration 

would have to be signed by a chief 

officer of the company, and would have 

to be made at least 30 days prior to the 

introduction into commerce of any 

vehicles for each model year for which 

the small entity status is requested, but 

not later than December of the calendar 

year prior to the model year for which 

deferral is requested. For example, if a 

manufacturer will be introducing model 

year 2012 vehicles in October of 2011, 

then the small entity declaration would 

be due in September of 2011. If 2012 

model year vehicles are not planned for 

introduction until March of 2012, then 

the declaration would have to be 

submitted in December of 2011. Such 

entities are not automatically exempted 

from other EPA regulations for lightduty vehicles and light-duty trucks; 

therefore, absent this annual declaration 

EPA would assume that each entity was 

not deferred from compliance with the 

proposed greenhouse gas standards. 

d. Onboard Diagnostics (OBD) and CO2 

Regulations 

The light-duty on-board diagnostics 

(OBD) regulations require manufacturers 

to detect and identify malfunctions in 

all monitored emission-related 

powertrain systems or components.179 

Specifically, the OBD system is required 

to monitor catalysts, oxygen sensors, 

engine misfire, evaporative system 

leaks, and any other emission control 

systems directly intended to control 

emissions, such as exhaust gas 

recirculation (EGR), secondary air, and 

fuel control systems. The monitoring 

threshold for all of these systems or 

components is 1.5 times the applicable 

standards, which typically include 

NMHC, CO, NOX, and PM. EPA is 

confident that many of the emissionrelated systems and components 

currently monitored would effectively 

catch any malfunctions related to CO2 

emissions. For example, malfunctions 

resulting from engine misfire, oxygen 

sensors, the EGR system, the secondary 

air system, and the fuel control system 

would all have an impact on CO2 

emissions. Thus, repairs made to any of 

these systems or components should 

also result in an improvement in CO2 

emissions. In addition, EPA does not 

have data on the feasibility or 

effectiveness of monitoring various 

emission systems and components for 

CO2 emissions and does not believe it 

would be prudent to include CO2 

emissions without such information. 

Therefore, at this time, EPA does not 

plan to require CO2 emissions as one of 

the applicable standards required for the 

OBD monitoring threshold. EPA plans 

to evaluate OBD monitoring technology, 

with regard to monitoring CO2 

emissions-related systems and 

components, and may choose to propose 

to include CO2 emissions as part of the 

OBD requirements in a future regulatory 

179 40 CFR 86.1806–04. 
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action. EPA requests comment as to 

whether this is appropriate at this time, 

and specifically requests any data that 

would support the need for CO2-related 

components that could or should be 

monitored via an OBD system. 

e. Applicability of Current High 

Altitude Provisions to Greenhouse 

Gases 

EPA is proposing that vehicles 

covered by this proposal meet the CO2, 

N2O and CH4 standard at altitude. The 

CAA requires emission standards under 

section 202 to apply at all altitudes.180 

EPA does not expect vehicle CO2, CH4, 

or N2O emissions to be significantly 

different at high altitudes based on 

vehicle calibrations commonly used at 

all altitudes. Therefore, EPA is 

proposing to retain its current high 

altitude regulations so manufacturers 

would not normally be required to 

submit vehicle CO2 test data for high 

altitude. Instead, they would submit an 

engineering evaluation indicating that 

common calibration approaches will be 

utilized at high altitude. Any deviation 

in emission control practices employed 

only at altitude would need to be 

included in the auxiliary emission 

control device (AECD) descriptions 

submitted by manufacturers at 

certification. In addition, any AECD 

specific to high altitude would be 

required to include emissions data to 

allow EPA evaluate and quantify any 

emission impact and validity of the 

AECD. EPA requests comment on this 

approach, and specifically requests data 

on impact of altitude on FTP and HFET 

CO2 emissions. 

f. Applicability of Standards to 

Aftermarket Conversions 

With the exception of the small entity 

deferment option EPA is proposing, 

EPA’s emission standards, including the 

proposed greenhouse gas standards, 

would continue to apply as stated in the 

applicability sections of the relevant 

regulations. The proposed greenhouse 

gas standards are being incorporated 

into 40 CFR part 86, subpart S, the 

provisions of which include exhaust 

and evaporative emission standards for 

criteria pollutants. Subpart S includes 

requirements for new light-duty 

vehicles, light-duty trucks, mediumduty passenger vehicles, Otto-cycle 

complete heavy-duty vehicles, and some 

incomplete light-duty trucks. Subpart S 

is currently specifically applicable to 

aftermarket conversion systems, 

aftermarket conversion installers, and 

aftermarket conversion certifiers, as 

those terms are defined in 40 CFR 

180 See CAA 206(f). 

85.502. EPA expects that some 

aftermarket conversion companies 

would qualify for and seek the small 

entity deferment, but those that do not 

qualify would be required to meet the 

applicable emission standards, 

including the proposed greenhouse gas 

standards. 

9. Miscellaneous Revisions to Existing 

Regulations 

a. Revisions and Additions to 

Definitions 

EPA is proposing to amend its 

definitions of ‘‘engine code,’’ 

‘‘transmission class,’’ and ‘‘transmission 

configuration’’ in its vehicle 

certification regulations (Part 86) to 

conform with the definitions for those 

terms in its fuel economy regulations 

(Part 600). The exact terms in Part 86 are 

used for reporting purposes and are not 

used for any compliance purpose (e.g., 

an engine code would not determine 

which vehicle was selected for emission 

testing). However, the terms are used for 

this purpose in Part 600 (e.g., engine 

codes, transmission class, and 

transmission configurations are all 

criteria used to determine which 

vehicles are to be tested for the purposes 

of establishing corporate average fuel 

economy). Here, EPA is proposing that 

the same vehicles tested to determine 

corporate average fuel economy also be 

tested to determine fleet average CO2, so 

the same definitions should apply. Thus 

EPA is proposing to amend its Part 86 

definitions of the above terms to 

conform to the definitions in Part 600. 

To bring EPA’s fuel economy 

regulations in Part 600 into conformity 

with this proposal for fleet average CO2 

and NHTSA’s reform truck regulations 

two amendments are proposed. First, 

the definition of ‘‘footprint’’ that is 

proposed in this rule is also being 

proposed for addition to EPA’s Part 86 

and 600 regulations. This definition is 

based on the definition promulgated by 

NHTSA at 49 CFR 523.2. Second, EPA 

is proposing to amend its model year 

CAFE reporting regulations to include 

the footprint information necessary for 

EPA to determine the reformed truck 

standards and the corporate average fuel 

economy. This same information is 

proposed to be included in this proposal 

for fleet average CO2 and fuel economy 

compliance. 

b. Addition of Ethanol Fuel Economy 

Calculation Procedures 

EPA is proposing to add calculation 

procedures to part 600 for determining 

the carbon-related exhaust emissions 

and calculating the fuel economy of 

vehicles operating on ethanol fuel. 

Manufacturers have been using these 

procedures as needed, but the regulatory 

language—which specifies how to 

determine the fuel economy of gasoline, 

diesel, compressed natural gas, and 

methanol fueled vehicles—has not 

previously been brought up-to-date to 

provide procedures for vehicles 

operating on ethanol. Thus EPA is 

proposing a carbon balance approach 

similar to other fuels for the 

determination of carbon-related exhaust 

emissions for the purpose of 

determining fuel economy and for 

compliance with the proposed fleet 

average CO2 standards. The carbon 

balance formula is similar to that for 

methanol, except that ethanol-fueled 

vehicles must also measure the 

emissions of ethanol and acetaldehyde. 

The proposed carbon balance equation 

for determining fuel economy is as 

follows, where CWF is the carbon 

weight fraction of the fuel and CWFexHC 

is the carbon weight fraction of the 

exhaust hydrocarbons: 

mpg = (CWF × SG × 3781.8)/((CWFexHC× HC) 

+ (0.429 × CO) + (0.273 × CO2) + (0.375 

× CH3OH) + (0.400 × HCHO) + (0.521 × 

C2H5OH) + (0.545 × C2H4O)) 

The proposed equation for 

determining the total carbon-related 

exhaust emissions for compliance with 

the CO2 fleet average standards is the 

following, where CWFexHC is the carbon 

weight fraction of the exhaust 

hydrocarbons: 

CO2-eq = (CWFexHC× HC) + (0.429 × CO) + 

(0.375 × CH3OH) + (0.400 × HCHO) + 

(0.521 × C2H5OH) + (0.545 × C2H4O) + 

CO2. 

EPA requests comment on the use of 

these formulae to determine fuel 

economy and carbon emissions. 

c. Revision of Electric Vehicle 

Applicability Provisions 

In 1980 EPA issued a rule that 

provided for the inclusion of electric 

vehicles in the CAFE program.181 EPA 

now believes that certain provisions of 

the regulations should be updated to 

reflect the current state of motor vehicle 

emission and fuel economy regulations. 

In particular, EPA believes that the 

exemption of electric vehicles in certain 

cases from fuel economy labeling and 

CAFE requirements should be 

reevaluated and revised. 

The rule created an exemption for 

electric vehicles from fuel economy 

labeling in the following cases: (1) If the 

electric vehicles are produced by a 

company that produces only electric 

vehicles; and (2) if the electric vehicles 

are produced by a company that 

181 45 FR 49256, July 24, 1980. 
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49576 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

produces fewer than 10,000 vehicles of 

all kinds worldwide. EPA believes that 

this exemption language is no longer 

appropriate and proposes to delete it 

from the affected regulations. First, 

since 1980 many regulatory provisions 

have been put in place to address the 

concerns of small manufacturers and 

enable them to comply with fuel 

economy and emission programs with 

reduced burden. EPA believes that all 

small volume manufacturers should 

compete on a fair and level regulatory 

playing field and that there is no longer 

a need to treat small volume electric 

vehicles any differently than small 

volume manufacturers of other types of 

vehicles. Current regulations contain 

streamlined certification procedures for 

small companies, and because electric 

vehicles emit no direct pollution there 

is effectively no certification emission 

testing burden. For example, the 

proposed greenhouse gas regulations 

contain a provision allowing the 

exemption of certain small entities. 

Meeting the requirements for fuel 

economy labeling and CAFE will entail 

a testing, reporting, and labeling burden, 

but these burdens are not extraordinary 

and should be applied equally to all 

small volume manufacturers, regardless 

of the fuel that moves their vehicles. 

EPA has been working with existing 

electric vehicle manufacturers on fuel 

economy labeling, and EPA believes it 

is important for the consumer to have 

impartial, accurate, and useful label 

information regarding the energy 

consumption of these vehicles. Second, 

EPCA does not provide for an 

exemption of electric vehicles from 

NHTSA’s CAFE program, and NHTSA 

regulations regarding the applicability 

of the CAFE program do not provide an 

exemption for electric vehicles. Third, 

the blanket exemption for any 

manufacturer of only electric vehicles 

assumed at the time that these 

companies would all be small, but the 

exemption language inappropriately did 

not account for size and would allow 

large manufacturers to be exempt as 

well. Finally, because of growth 

expected in the electric vehicle market 

in the future, EPA believes that the 

labeling and CAFE regulations need to 

be designed to more specifically 

accommodate electric vehicles and to 

require that consumers be provided 

with appropriate information regarding 

these vehicles. For these reasons EPA is 

proposing revisions to 40 CFR Part 600 

applicability regulations such that these 

electric vehicle exemptions are deleted 

starting with the 2012 model year. 

d. Miscellaneous Conforming 

Regulatory Amendments 

Throughout the regulations EPA has 

made a number of minor amendments to 

update the regulations as needed or to 

conform with amendments discussed in 

this preamble. For example, for 

consistency with the ethanol fuel 

economy calculation procedures 

discussed above, EPA has amended 

regulations where necessary to require 

the collection of emissions of ethanol 

and acetaldehyde. Other changes are 

made to applicability sections to remove 

obsolete regulatory requirements such 

as phase-ins related to EPA’s Tier 2 

emission standards program, and still 

other changes are made to better 

accommodate electric vehicles in EPA 

emission control regulations. Not all of 

these minor amendments are noted in 

this preamble, thus the reader should 

carefully evaluate the proposed 

regulatory text to ensure a complete 

understanding of the regulatory changes 

being proposed by EPA. 

10. Warranty, Defect Reporting, and 

Other Emission-Related Components 

Provisions 

Under section 207(a) of the CAA, 

manufacturers must warrant that a 

vehicle is designed to comply with the 

standards and will be free from defects 

that may cause it to not comply over the 

specified period which is 2 years/24,000 

miles (whichever is first) or, for major 

emission control components, 8 years/ 

80,000 miles. Under certain conditions, 

manufacturers may be liable to replace 

failed emission components at no 

expense to the owner. EPA regulations 

define ‘‘emission related parts’’ for the 

purpose of warranty. This definition 

includes parts which must function 

properly to assure continued 

compliance with the emission 

standards.182 

The air conditioning system and its 

components have not previously been 

covered under the CAA warranty 

provisions. However, the proposed A/C 

leakage and A/C-related CO2 emission 

standards are dependent upon the 

proper functioning of a number of 

components on the A/C system, such as 

rings, fittings, compressors, and hoses. 

Therefore, EPA is proposing that these 

components be included under the CAA 

section 207(a) emission warranty 

provisions, with a warranty of 2 years/ 

24,000 miles. 

EPA requests comment as to whether 

any other parts or components should 

be designated as ‘‘emission related 

parts’’ subject to warranty and defect 

182 40 CFR 85.2102(14). 

reporting provisions under this 

proposal. 

11. Light Duty Vehicles and Fuel 

Economy Labeling 

American consumers need accurate 

and meaningful information about the 

environmental and fuel economy 

performance of new light vehicles. EPA 

believes it is important that the fueleconomy label affixed to the new 

vehicles provide consumers with the 

critical information they need to make 

smart purchase decisions. This is a 

special challenge in light of the 

expected increase in market share of 

electric and other advanced technology 

vehicles. Consumers may need new and 

different information than today’s 

vehicle labels provide in order to help 

them understand the energy use and 

associated cost of owning these electric 

and advanced technology vehicles. As 

discussed below, these two issues are 

key to determining whether the current 

MPG-based fuel-economy label is 

adequate. 

Therefore, as part of this action, EPA 

seeks comments on issues surrounding 

consumer vehicle labeling in general, 

and labeling of advanced technology 

vehicles in particular. EPA also plans to 

initiate a separate rulemaking to explore 

in detail the information displayed on 

the fuel economy label and the 

methodology for deriving that 

information. The purposes of this new 

rulemaking would be to ensure that 

American consumers continue to have 

the most accurate, meaningful, and 

useful information available to them 

when purchasing new vehicles, and that 

the information is presented to them in 

clear and understandable terms. 

a. Background 

EPA has considerable experience in 

providing vehicle information to 

consumers through its fuel-economy 

labeling activities and related web-based 

programs. Under 49 U.S.C. 32908(b) 

EPA is responsible for developing the 

fuel economy labels that are posted on 

window stickers of all new light duty 

cars and trucks sold in the U.S. and, 

beginning with the 2011 model year, on 

all new medium-duty passenger 

vehicles (a category that includes large 

sport-utility vehicles and passenger 

vans). The statutory requirements 

established by EPCA require that the 

label contain the following: 

• The fuel economy of the vehicle; 183 

• The estimated annual fuel cost of 

operating the vehicle; 

183 ‘‘Fuel economy’’ per the statute is miles per 

gallon of gasoline (or equivalent amount of other 

fuel). 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49577 

• The range of fuel economy of 

comparable vehicles among all 

manufacturers; 

• A statement that a fuel economy 

booklet is available from the dealer; 184 

and 

• The amount of the ‘‘gas guzzler’’ tax 

imposed on the vehicle by the Internal 

Revenue Service. 

• Other information required or 

authorized by EPA that is related to the 

information required above. 

Fuel economy is defined as the 

number of miles traveled by an 

automobile for each gallon of gasoline 

(or equivalent amount of other fuel). It 

is relatively easy to determine the miles 

per gallon (MPG) for vehicles that use 

liquid fuels (e.g., gasoline or diesel), but 

an expression that uses gallons— 

whether miles per gallon or gallons per 

mile—may not be a useful metric for 

vehicles that have limited to no 

operation on liquid fuel such as electric 

or compressed natural gas vehicles. The 

mpg metric is the one generally used 

today to provide comparative fuel 

economy information to consumers. 

As part of its vehicle certification, 

CAFE, and fuel economy labeling 

authorities, EPA works with 

stakeholders on the testing and other 

regulatory requirements necessary to 

bring advanced technology vehicles to 

market. With increasing numbers of 

advanced technology vehicles beginning 

to be sold, EPA believes it is now 

appropriate to address potential 

regulatory and certification issues 

associated with these technologies 

including how best to provide relevant 

consumer information about their 

environmental impact, energy 

consumption, and cost. 

b. Test Procedures 

As discussed in this notice, there are 

explicit and very long-standing test 

procedures and calculation 

methodologies associated with CAFE 

that EPA uses to test conventionallyfueled vehicles and to calculate their 

fuel economy. These test procedures 

and calculations also generally apply to 

advanced technology vehicles (e.g., an 

electric (EV) or plug-in hybrid vehicle 

(PHEV)). 

The basic test procedure for an 

electric vehicle follows a standardized 

practice—an EV is fully charged and 

then driven over the city cycle (Urban 

Dynamometer Drive Schedule) until the 

vehicle can no longer maintain the 

required drive cycle vehicle speed. For 

some vehicles, this could require 

operation over multiple drive cycles. 

184 EPA and DOE jointly publish the annual Fuel 

Economy Guide and distribute it to dealers. 

The EV is then fully recharged and the 

AC energy to the charger is recorded. 

To derive the CAFE value for electric 

vehicles, the amount of AC energy 

needed to recharge the battery is 

divided by the range the vehicle reached 

in the repeated city drive cycle. This 

calculation provides a raw CAFE energy 

consumption value expressed in 

kilowatt hours per 100 miles. The raw 

CAFE number is then converted to miles 

per gallon of equivalent gasoline using 

a Department of Energy (DOE) 

conversion factor of 82,700 Kwhr/gallon 

of gasoline.185 The DOE conversion 

factor combines several adjustments 

including: an adjustment similar to the 

statutory 6.67 multiplier credit 186 used 

in deriving the final CAFE value for 

alternative fueled vehicles; a factor 

representing the gasoline-equivalent 

energy content of electricity; and 

various adjustments to account for the 

relative efficiency of producing and 

transporting the electricity. The 

resulting value after the DOE conversion 

factor is applied becomes the final 

CAFE city value. 

The label value calculation for an EV 

uses a different conversion factor than 

the CAFE value calculation. To come up 

with the final city fuel economy label 

value for an EV, a conversion factor of 

33,705 Kwhr/gallon of gasoline 

equivalent is applied to the raw 

consumption number instead of the 

82,700 Kwhr/gallon used for CAFE. The 

conversion factor used for labeling 

purposes represents only the gasolineequivalent energy content of electricity, 

without the multiplier credit and other 

adjustments used in the CAFE 

calculation. The consumption, now 

expressed as a fuel economy in miles 

per gallon equivalent, is then applied to 

the derived 5-cycle equation required 

under EPA’s fuel economy labeling 

regulations. The above process is then 

repeated for the EV highway fuel 

economy label number. Finally, the 

combined city/highway numbers for the 

EV use the same 55/45 weighting as 

conventional vehicles to determine the 

final fuel economy label values. CAFE 

numbers end up being significantly 

higher for EVs than the associated fuel 

economy label values, both because a 

higher adjustment factor applies under 

CAFE regulations and also because 

other real-world adjustments such as the 

5-cycle test are not applied to the CAFE 

values. 

For PHEVs, a similar process would 

be followed, except that PHEVs require 

testing in both charge sustain (CS) and 

charge depleting (CD) modes to capture 

185 49 U.S.C. 32904 and 10 CFR 474.3. 


186 49 U.S.C. 32905. 


how these vehicles operate. For charge 

sustain modes, PHEVs essentially 

operate as conventional Hybrid Electric 

Vehicles (HEVs). PHEVs therefore test in 

all 5-cycles (for further information on 

these test cycles, see Section III.C.4) just 

as HEVs do for CS fuel economy. For CD 

fuel economy, PHEVs are only required 

to test on the Urban Dynamometer Drive 

Schedule and Highway Fuel Economy 

cycles just like other alternative fueled 

vehicles—the 5-cycle fuel economy 

testing is optional in the CD mode. 

There are additional processes that 

address different PHEV modes, such as 

for PHEVs that operate solely on 

electricity throughout the CD mode. 

As this discussion shows, the CAFE 

and fuel economy labeling test 

procedures and calculations for 

advanced technology vehicles such as 

EVs and PHEVs can be very 

complicated. EPA is interested in 

comments on these processes, including 

views on the appropriate use of 

adjustment factors. Currently in 

guidance, EPA references SAE J1634 for 

EV range and consumption test 

procedures. EPA currently includes the 

‘‘California Exhaust Emission Standards 

and Test Procedures for 2003 and 

Subsequent Model Zero-Emission 

Vehicles, in the Passenger Car, Light 

Truck, and Medium-duty Vehicle 

Classes’’ by reference in 40 CFR 86.1. As 

California requirements and SAE test 

procedures are updated these may be 

included by reference in the future. 

c. Current Fuel Economy Label 

In 2006 EPA redesigned the window 

stickers to make them more informative 

for consumers. More particular, the 

redesigned stickers more prominently 

feature annual fuel cost information, to 

provide contemporary and easy-to-use 

graphics for comparing the fuel 

economy of different vehicles, to use 

clearer text, and to include a Web site 

reference to www.fueleconomy.gov 

which provides additional information. 

In addition, EPA updated how the city 

and highway fuel economy values were 

calculated, to reflect typical real-world 

driving patterns.187 This rulemaking 

involved significant stakeholder 

outreach in determining how best to 

calculate and display this new 

information. The feedback EPA has 

received to date on the new label design 

and values has been generally very 

positive. 

During the 2006 label rulemaking 

process EPA requested comments on 

187 71 FR 77872 (December 27, 2006). Fuel 

Economy Labeling of Motor Vehicles: Revisions to 

Improve Calculations of Fuel Economy Estimates. 

U.S. EPA. 
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49578 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

how a fuel consumption metric (such as 

gallons per 100 miles) could be used 

and represented to the public, including 

presentation in the annual Fuel 

Economy Guide. EPA received a number 

of comments from both vehicle 

manufacturers and consumer 

organizations, suggesting that the MPG 

measures can be misleading and that a 

fuel consumption metric might be more 

meaningful to consumers than the 

established MPG metric found on fuel 

economy labels. The reason is that fuel 

consumption metric, directly measures 

the amount of fuel used and is thus 

directly related to cost that consumers 

incur when filling up. 

The problem with the MPG metric is 

that it is inversely related to fuel 

consumption and cost. As higher MPG 

values are reached, the relative impact 

of these higher values on fuel 

consumption and fuel costs decreases. 

For example, a 25 percent increase in 

gallons per 100 miles will always lead 

to a 25 percent increase in the fuel cost, 

but a similar 25 percent increase in 

MPG will have varying impacts on 

actual fuel cost depending on whether 

the percent increase occurs to a low or 

high MPG value. Many consumers do 

not understand this nonlinear 

relationship between MPG and fuel 

costs. Evidence suggest that people tend 

to see the MPG as being linear with fuel 

cost, which will lead to erroneous 

decisions regarding vehicle purchases. 

Figure III.E.11–1 below illustrates the 

issue; one can see that changes in MPG 

at low MPG levels can result in large 

changes in the fuel cost, while changes 

in MPG values at high MPG levels result 

in small changes in the fuel cost. For 

example, a change from 10 to 15 MPG 

will reduce the 10-mile fuel cost from 

$2.50 to $1.60, but a similar increase in 

MPG from 20 to 25 MPG will only 

reduce the 10-mile fuel cost by less than 

$0.30. 

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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49579 

Because of the potential for 

consumers to misunderstand this MPG/ 

cost relationship, commenters on the 

2006 labeling rule universally agreed 

that any change to the label metric 

should involve a significant public 

education campaign directed toward 

both dealers and consumers. 

In 2006, EPA did not include a 

consumption-based metric on the 

redesigned fuel economy label in 2006. 

It was concerned about potential 

confusion associated with introducing a 

second metric on the label (MPG is a 

required element, as noted above). EPA 

has developed an interactive feature on 

www.fueleconomy.gov which allows 

consumers, while viewing data on a 

specific vehicle, to switch units between 

the MPG and gallons per 100 miles 

metrics. The tool also displays the cost 

and the amount of fuel needed to drive 

25 miles. As indicated above, however, 

EPA is alert to the problems with the 

MPG measure and the importance of 

providing consumers with a clear sense 

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49580 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

of the consequences of their purchasing 

decisions; a gallon-per mile measure 

would have significant advantages. EPA 

plans to seek comment and engage in 

extensive public debate about fuel 

consumption and other appropriate 

consumer information metrics as part of 

a new labeling rule initiative. EPA also 

welcomes comments on this topic in 

response to this GHG proposal. 

d. Labeling for Advanced Technology 

Vehicles 

Even though a fuel consumption 

metric may more directly represent 

likely fuel costs than a fuel economy 

metric, any expression that uses 

gallons—whether miles per gallon or 

gallons per mile—is not a useful metric 

for vehicles that have limited to no 

operation on liquid fuel (e.g., electricity 

or compressed natural gas). For 

example, PHEVs and extended range 

electric vehicles (EREVs) can use two 

types of energy sources: (1) An onboard 

battery, charged by plugging the vehicle 

into the electrical grid via a 

conventional wall outlet, to power an 

electric motor, as well as (2) a gas or 

diesel-powered engine to propel the 

vehicle or power a generator used to 

provide electricity to the electric motor. 

Depending on how these vehicles are 

operated, they can use electricity 

exclusively, never use electricity and 

operate like a conventional hybrid, or 

operate in some combination of these 

two modes. The use of a MPG figure 

alone would not account for the 

electricity used to propel the vehicle. 

EPA has worked closely with 

numerous stakeholders including 

vehicle manufacturers, the Society of 

Automotive Engineers (SAE), the State 

of California, the Department of Energy 

(DOE) and others to develop possible 

approaches for both estimating fuel 

economy and labeling vehicles that can 

operate using more than one energy 

source. At the present time, EPA 

believes the appropriate method for 

estimating fuel economy of PHEVs and 

EREVs would be a weighted average of 

fuel economy for the two modes of 

operation. A methodology developed by 

SAE and DOE to predict the fractions of 

total distance driven in each mode of 

operation (electricity and gas) uses a 

term known as a utility factor (UF). By 

using a utility factor, it is possible to 

determine a weighted average for fuel 

economy of the electric and gasoline 

modes. For example, a UF of 0.8 would 

indicate that a PHEV or EREV operates 

in an all electric mode 80% of the time 

and uses the gasoline engine the other 

20% of the time. In this example, the 

weighted average fuel economy value 

would be influenced more by the 

electrical operation than the gasoline 

operation. 

Under this approach, a UF could be 

assigned to each successive fuel 

economy test until the battery charge 

was depleted and the PHEV or EREV 

needed power from the gasoline engine 

to propel the vehicle or to recharge the 

battery. One minus the sum of all the 

utility factors would then represent the 

fraction of driving performed in this 

‘‘gasoline mode.’’ Fuel economy could 

then be expressed as: 

1 FEMPG = UF 1 UFi i −∑ ∑ +

FEi FEgasoline

Likewise, the electrical consumption 

would be expressed by adding the fuel 

consumption from each mode. Since 

there is no electrical consumption in 

hybrid mode, the equation for electricity 

consumption would be as follows: 

Utility factors could be cycle specific 

not only due to different battery ranges 

on different test cycles but also due to 

the fact that ‘‘highway’’ type driving 

may imply longer trips than urban 

driving. That is to say that the average 

city trip could be shorter than the 

average highway trip. 

e. Request for Comments 

EPA is interested in comments on 

both topics raised in this section. For 

the methodology, we are interested in 

comments addressing how the utility 

factor is calculated and which data 

should be used in establishing the UF. 

Additionally, commenters should 

address: The appropriateness of this 

approach for estimating fuel economy 

for PHEVs and EREVs, including the 

concept of using a UF to determine the 

fuel economy for vehicles operated in 

multiple modes; the appropriate form 

and value of the factor, including the 

type of data that would be necessary to 

confidently develop it accurately; and 

availability of other potential 

methodologies for determining fuel 

economy for vehicles that can operate in 

multiple modes, such as ‘‘all electric’’ 

and ‘‘hybrid,’’ including the use of fuel 

consumption, cost, GHG emissions, or 

other metrics in addition to miles per 

gallon. 

EPA is also requesting comment on 

how the agency can satisfy statutory 

labeling requirements while providing 

relevant information to consumers. For 

example, the statute indicates that EPA 

may provide other related items on the 

label beyond those that are required.188 

EPA is interested in receiving comments 

on the potential approaches and 

supporting data we might consider for 

adding additional information regarding 

fuel economics while maintaining our 

statutory obligation to report MPG on 

the label. 

There are a number of different 

metrics that are available that could be 

useful in this regard. Two possible 

options would be to show consumption 

in fuel use per distance (e.g., gallons/ 

100 miles) or in cost per distance (e.g., 

$/100 miles). As discussed above, these 

two metrics have benefits over a straight 

mpg value in showing a more direct 

relationship between fuel consumption 

and cost. The cost/distance metric has 

an added potential benefit of providing 

a common basis for comparing 

differently fueled or powered vehicles, 

for example being able to show the cost 

of gasoline used over a specified 

distance or time for a conventional 

gasoline-powered vehicle in comparison 

to the gasoline and electricity used over 

the same period for a plug-in hybrid 

vehicle. Another approach would be to 

use a metric that provides information 

about a vehicle’s greenhouse gas 

emissions per unit of travel, such as 

carbon dioxide equivalent grams per 

mile (g CO2e/mi). This type of metric 

would allow consumers to directly 

compare among vehicles on the basis of 

their overall greenhouse gas impact. A 

total annual energy cost would be 

another way to look at this information, 

and is currently used on the fuel 

economy label. As is currently done, 

EPA would need to determine and show 

a common set of fuel costs used to 

calculate such values, recognizing that 

energy costs vary across the country. 

The Agency is also interested in 

comments on the usefulness of adding 

other types of information, such as an 

estimated driving range for electric 

vehicles. The label design is also an 

important issue to consider and any 

changes to the existing label would need 

to show information in a technologically 

accurate, meaningful and 

understandable manner, while ensuring 

that the label does not become 

overcrowded and difficult for 

consumers to comprehend. EPA is also 

interested in what and how other 

information paths, such as web-based 

programs, could be used to enhance the 

consumer education process. 

188 49 U.S.C. 3290(b)(F). 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49581 

F. How Would This Proposal Reduce III.F–1 shows emissions of CO2, share is growing over time, reaching an 

GHG Emissions and Their Associated methane, nitrous oxide and air estimated 20 percent of U.S. emissions 

Effects? conditioning refrigerants on a CO2- by 2030 in the absence of control. As 

This action is an important step equivalent basis for calendar years 2010, discussed later in this section, this 

towards curbing steady growth of GHG 2020, 2030, 2040 and 2050. U.S. GHGs steady rise in GHG emissions is 

emissions from cars and light trucks. In are estimated to make up roughly 15 associated with numerous adverse 

the absence of control, GHG emissions percent of total worldwide emissions, impacts on human health, food and 

worldwide and in the U.S. are projected and the contribution of direct emissions agriculture, air quality, and water and 

to continue steady growth; Table from cars and light trucks to this U.S. forestry resources. 

TABLE III.F–1—REFERENCE CASE GHG EMISSIONS BY CALENDAR YEAR 

[MMTCO2 Eq] 

2010 2020 2030 2040 2050 

All Sectors (Worldwide) a ............................................................................................. 

All Sectors (U.S. Only) a ............................................................................................... 

U.S. Cars/Light Truck Only b ........................................................................................ 

41,016 

7,118 

1,359 

48,059 

7,390 

1,332 

52,870 

7,765 

1,516 

56,940 

8,101 

1,828 

60,209 

8,379 

2,261 

a ADAGE model projections, U.S. EPA.189
 

b MOVES (2010), OMEGA Model (2020–50) U.S. EPA. See DRIA Chapter 5.3 for modeling details. 


EPA’s proposed GHG rule, if 

finalized, will result in significant 

reductions as newer, cleaner vehicles 

come into the fleet, and the rule is 

estimated to have a measurable impact 

on world global temperatures. As 

discussed in Section I, this GHG 

proposal is part of a joint National 

Program such that a large majority of the 

projected benefits would be achieved 

jointly with NHTSA’s proposed CAFE 

standards which are described in detail 

in Section IV of this preamble. EPA 

estimates the reductions attributable to 

the GHG program over time assuming 

the proposed 2016 standards continue 

indefinitely post-2016,190 compared to a 

baseline scenario in which the 2011 

model year fuel economy standards 

continue beyond 2011. 

Using this approach, EPA estimates 

these standards would cut annual 

fleetwide car and light truck tailpipe 

CO2 emissions 21 percent by 2030, 

when 90 percent of car and light truck 

miles will be travelled by vehicles 

meeting the new standards. Roughly 20 

percent of these reductions are due to 

emission reductions from gasoline 

extraction, production and distribution 

processes as a result of reduced gasoline 

demand associated with this proposal. 

Some of the overall emission reductions 

also come from projected improvements 

189 U.S. EPA (2009). ‘‘EPA Analysis of the 

American Clean Energy and Security Act of 2009: 

H.R. 2454 in the 111th Congress.’’ U.S. 

Environmental Protection Agency, Washington, DC, 

USA. (www.epa.gov/climatechange/economics/ 

economicanalyses.html) 

190 This analysis does not include the EISA 

requirement for 35 MPG through 2020 or 

California’s Pavley 1 GHG standards. The proposed 

standards are intended to supersede these 

requirements, and the baseline case for comparison 

is the emissions that would result without further 

action above the currently promulgated fuel 

economy standards. 

in the efficiency of vehicle air 

conditioning systems, which will 

substantially reduce direct emissions of 

HFCs, one of the most potent 

greenhouse gases, as well as indirect 

emissions of tailpipe CO2 emissions 

attributable to reduced engine load from 

air conditioning. In total, EPA estimates 

that compared to a baseline of indefinite 

2011 model year standards, net GHG 

emission reductions from the proposed 

program would be 325 million metric 

tons CO2-equivalent (MMTCO2eq) 

annually by 2030, which represents a 

reduction of 4 percent of total U.S. GHG 

emissions and 0.6 percent of total 

worldwide GHG emissions projected in 

that year. This estimate accounts for all 

upstream fuel production and 

distribution emission reductions, 

vehicle tailpipe emission reductions 

including air conditioning benefits, as 

well as increased vehicle miles travelled 

(VMT) due to the ‘‘rebound’’ effect 

discussed in Section III.H. EPA 

estimates this would be the equivalent 

of removing nearly 60 million cars and 

light trucks from the road in this 

timeframe. 

EPA projects the total reduction of the 

program over the full life of model year 

2012–2016 vehicles is about 950 

MMTCO2eq, with fuel savings of 76 

billion gallons (1.8 billion barrels) of 

gasoline over the life of these vehicles, 

assuming that some manufacturers take 

advantage of low-cost HFC reduction 

strategies to help meet these proposed 

standards. 

These reductions are projected to 

reduce global mean temperature by 

approximately 0.007–0.016°C by 2100, 

and global mean sea level rise is 

projected to be reduced by 

approximately 0.06–0.15 cm by 2100. 

1. Impact on GHG Emissions 

a. Calendar Year Reductions Due to 

GHG Standards 

This action, if finalized, will reduce 

GHG emissions emitted directly from 

vehicles due to reduced fuel use and 

more efficient air conditioning systems. 

In addition to these ‘‘downstream’’ 

emissions, reducing CO2 emissions 

translates directly to reductions in the 

emissions associated with the processes 

involved in getting petroleum to the 

pump, including the extraction and 

transportation of crude oil, and the 

production and distribution of finished 

gasoline (termed ‘‘upstream’’ 

emissions). Reductions from tailpipe 

GHG standards grow over time as the 

fleet turns over to vehicles affected by 

the standards, meaning the benefit of 

the program will continue as long as the 

oldest vehicles in the fleet are replaced 

by newer, lower CO2 emitting vehicles. 

EPA is not projecting any reductions 

in tailpipe CH4 or N2O emissions as a 

result of these proposed emission caps, 

which are meant to prevent emission 

backsliding and to bring diesel vehicles 

equipped with advanced technology 

aftertreatment into alignment with 

current gasoline vehicle emissions. 

As detailed in the DRIA, EPA 

estimated calendar year tailpipe CO2 

reductions based on pre- and postcontrol CO2 gram per mile levels from 

EPA’s OMEGA model and assumed to 

continue indefinitely into the future, 

coupled with VMT projections from 

AEO2009. These estimates reflect the 

real-world CO2 emissions reductions 

projected for the entire U.S. vehicle fleet 

in a specified calendar year, including 

the projected effect of air conditioning 

credits, TLAASP credits and FFV 

credits. EPA also estimated full lifetime 

reductions for model years 2012–2016 
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49582 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

using pre- and post-control CO2 levels 

projected by the OMEGA model, 

coupled with projected vehicle sales 

and lifetime mileage estimates. These 

estimates reflect the real-world CO2 

emissions reductions projected for 

model years 2012 through 2016 vehicles 

over their entire life. 

This proposal would allow 

manufacturers to earn credits for 

improved vehicle air conditioning 

efficiency. Since these improvements 

are relatively low cost, EPA projects that 

manufacturers will take advantage of 

this flexibility, leading to reductions 

from emissions associated with vehicle 

air conditioning systems. As explained 

above, these reductions will come from 

both direct emissions of air conditioning 

refrigerant over the life of the vehicle 

and tailpipe CO2 emissions produced by 

the increased load of the A/C system on 

the engine. In particular, EPA estimates 

that direct emissions of HFCs, one of the 

most potent greenhouse gases, would be 

reduced 40 percent from light-duty 

vehicles when the fleet has turned over 

to more efficient vehicles. The fuel 

savings derived from lower tailpipe CO2 

would also lead to reductions in 

upstream emissions. Our estimated 

reductions from the A/C credits program 

are based on our analysis of how 

manufacturers are expected to take 

advantage of this credit opportunity in 

complying with the CO2 fleetwide 

average tailpipe standards. 

Upstream emission reductions 

associated with the production and 

distribution of fuel were estimated using 

emission factors from DOE’s GREET1.8 

model, with some modifications as 

detailed in the DRIA. These estimates 

include both international and domestic 

emission reductions, since reductions in 

foreign exports of finished gasoline and/ 

or crude would make up a significant 

share of the fuel savings resulting from 

the proposed GHG standards. Thus, 

significant portions of the upstream 

GHG emission reductions will occur 

outside of the U.S.; a breakdown of 

projected international versus domestic 

reductions is included in the DRIA. 

Table III.F.1–1 shows reductions 

estimated from these proposed GHG 

standards assuming a pre-control case of 

2011 MY standards continuing 

indefinitely beyond 2011, and a postcontrol case in which 2016 MY 

standards continue indefinitely beyond 

2016. These reductions are broken down 

by upstream and downstream 

components, including air conditioning 

improvements, and also account for the 

offset from a 10 percent VMT ‘‘rebound’’ 

effect as discussed in Section III.H. 

Including the reductions from upstream 

emissions, total reductions are 

estimated to reach 325 MMTCO2eq 

annually by 2030 (a 21 percent 

reduction in U.S. car and light truck 

emissions), and grow to over 500 

MMTCO2eq in 2050 as cleaner vehicles 

continue to come into the fleet (a 23 

percent reduction in U.S. car and light 

truck emissions). 

TABLE III.F.1–1—PROJECTED NET GHG REDUCTIONS 

[MMTCO2 Eq per year] 

Calendar year 

2020 2030 2040 2050 

Net Reduction Due to Tailpipe Standards * ..................................................... 

Tailpipe Standards ........................................................................................... 

A/C—indirect CO2 ............................................................................................ 

A/C—direct HFCs ............................................................................................ 

Upstream ......................................................................................................... 

Percent reduction relative to U.S. reference (cars + light trucks) ................... 

Percent reduction relative to U.S. reference (all sectors) ............................... 

Percent reduction relative to worldwide reference .......................................... 

165.2 

107.7 

11.0 

13.5 

33.1 

12.4% 

2.2% 

0.3% 

324.6 

211.4 

21.1 

27.2 

64.9 

21.4% 

4.2% 

0.6% 

417.5 

274.1 

27.3 

32.1 

84.1 

22.8% 

5.2% 

0.7% 

518.5 

344.0 

34.2 

34.9 

105.5 

22.9% 

6.2% 

0.9% 

* Includes impacts of 10% VMT rebound rate presented in Table III.F.1–3. 

b. Lifetime Reductions for 2012–2016 2016 model year cars and trucks lifetime reductions of nearly 950 

Model Years affected by this proposal.191 These MMTCO2eq, with fuel savings of 76 

EPA also analyzed the emission 

reductions over the full life of the 2012– 

results, including both upstream and 

downstream GHG contributions, are 

presented in Table III.F.1–2, showing 

billion gallons (1.8 billion barrels) of 

gasoline. 

TABLE III.F.1–2—PROJECTED NET GHG REDUCTIONS 

[MMTCO2 Eq per year] 

Lifetime GHG Lifetime fuel 

Model year reduction savings 

(MMT CO2 EQ) (billion gallons) 

2012 ................................................................................................................................................................. 81.4 6.6 

2013 ................................................................................................................................................................. 125.0 10.0 

2014 ................................................................................................................................................................. 174.1 13.9 

2015 ................................................................................................................................................................. 243.2 19.5 

2016 ................................................................................................................................................................. 323.6 26.3 

Total Program Benefit .............................................................................................................................. 947.4 76.2 

191 As detailed in the DRIA, for this analysis the lifetime mileages for cars (190,000 miles) and trucks through 2030, a function of how far vehicles drive 

full life of the vehicle is represented by average (221,000 miles) averaged over calendar years 2012 per year and scrappage rates. 
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c. Impacts of VMT Rebound Effect 	 increase in VMT. Results are shown in of VMT rebound for the final rule. 

As noted above and discussed more Table III.F.1–3; using the 10 percent Although EPA has not directly

rebound rate results in an overall quantified the GHG emissions effect of fully in Section III.H., the effect of fuel 

cost on VMT (‘‘rebound’’) was emission increase of 26.4 MMTCO2eq using a lower rebound rate for this 

accounted for in our assessment of annually in 2030 (this increase is analysis, lowering the rebound rate 

economic and environmental impacts of accounted for in the reductions would reduce the emission increases in

presented in Tables III.F.1–1 and III.F.1– this proposed rule. A 10 percent Tables III.F.1–1 and III.F.1–2 in 

rebound case was used for this analysis, 	 2). Our estimated changes in CH4 or N2O proportion (i.e., zero rebound equals

meaning that VMT for affected model 	 emissions as a result of these proposed zero emissions effect), and, thus, would

years is modeled as increasing by 10 	 vehicle GHG standards are attributed increase our estimates of emission 

percent as much as the increase in fuel solely to this rebound effect. reductions due to these proposed 

economy; i.e., a 10 percent increase in As discussed in Section III.H, EPA standards. 

fuel economy would yield a 1.0 percent will be reassessing the appropriate rate 

TABLE III.F.1–3—GHG IMPACT OF 10% VMT REBOUND a 

[MMTCO2 Eq per year] 

2020 2030 2040 2050 

Total GHG Increase ................................................................................. 

Tailpipe & Indirect A/C CO2 ..................................................................... 

Upstream GHGs b .................................................................................... 

Tailpipe N2O ............................................................................................ 

Tailpipe CH4 ............................................................................................. 

13 .6 

10 .6 

2 .95 

0 .040 

0 .008 

26 .4 

20 .6 

5 .74 

0 .085 

0 .016 

34 .2 

26 .6 

7 .43 

0 .113 

0 .021 

42 .9 

33 .4 

9 .32 

0 .142 

0 .027 

a These impacts are included in the reductions shown in Table III.F.1–1 and III.F.1–2. 

b Upstream rebound impact calculated as upstream total CO2 effect times ratio of downstream tailpipe rebound CO2 effect to downstream tailpipe total CO2 effect. 

d. Analysis of Alternatives 	 manufacturers would use air As in the primary scenario, EPA 

conditioning improvements in identical assumed that the fleet complied with EPA analyzed two alternative penetrations as in the primary scenario. the standards. For full details on 

scenarios, including 4% and 6% annual Under these assumptions, EPA expects modeling assumptions, please refer to increases in 2 cycle (CAFE) fuel achieved fleetwide average emission DRIA Chapter 5. economy. In addition to this annual levels of 254 g/mile CO2 EQ (4%), and 

increase, EPA assumed that 	 230 g/mile CO2 EQ (6%) in 2016. 

TABLE III.F.1–4—CALENDAR YEAR IMPACTS OF ALTERNATIVE SCENARIOS 

Calendar year 

Scenario CY 2020 CY 2030 CY 2040 CY 2050 

Total GHG Reductions (MMT CO2EQ) ........................... 

Fuel Savings (Billion Gallons Gasoline Equivalent) ....... 

Primary ............................... 

4% ...................................... 

6% ...................................... 

Primary ............................... 

4% ...................................... 

6% ...................................... 

165.2 

152.8 

215.2 

13.4 

12.2 

17.8 

324.6 

305.9 

426.2 

26.2 

24.5 

35.1 

417.5 

394.1 

549.3 

33.9 

31.8 

45.5 

518.5 

489.3 

683.9 

42.6 

39.9 

57.1 

TABLE III.F.1–5—MODEL YEAR IMPACTS OF ALTERNATIVE SCENARIOS 

Model year lifetime 

Scenario MY 2012 MY 2013 MY 2014 MY 2015 MY 2016 Total 

Total GHG Reductions (MMT Primary ............... 81.4 125.0 174.1 243.2 323.6 947.4 

CO2EQ). 

4% ...................... 41.8 93.5 160.8 231.0 305.2 832.3 

6% ...................... 60.2 146.4 239.9 333.3 424.9 1,204.7 

Fuel Savings (Billion Gallons Gaso- Primary ............... 6.6 10.0 13.9 19.5 26.3 76.2 

line Equivalent). 

4% ...................... 3.1 7.2 12.7 18.4 24.7 66.1 

6% ...................... 4.7 11.9 19.7 27.4 35.2 99.0 

2. Overview of Climate Change Impacts regulation can remain in the atmosphere their effects on climate are long lasting. 

From GHG Emissions for decades to centuries, meaning that Greenhouse gas emissions come mainly 

(1) their concentrations become well-	 from the combustion of fossil fuels 

Once emitted, greenhouse gases mixed throughout the global atmosphere (coal, oil, and gas), with additional (GHG) that are the subject of this regardless of emission origin, and (2) contributions from the clearing of 
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49584 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

forests and agricultural activities. The 

transportation sector accounts for a 

portion, 28%, of US GHG emissions.192 

This section provides a broad 

overview of some of the impacts of GHG 

emissions. The best sources of 

information include the major 

assessment reports of both the 

Intergovernmental Panel on Climate 

Change (IPCC) and the U.S. Global 

Change Research Program (USGCRP, 

formerly referred to as the U.S. Climate 

Change Science Program). The IPCC and 

USGCRP assessments base their findings 

on the large body of individual, peerreviewed studies in the literature, and 

then the IPCC and USGCRP assessments 

themselves go through a transparent 

peer-reviewed process. The USGCRP 

reports, where possible, are specific to 

impacts in the U.S. and therefore 

represent the best available syntheses of 

relevant impacts. 

Most recently, the USGCRP released a 

report entitled ‘‘Global Climate Change 

Impacts in the United States’’.193 The 

report summarizes the science and the 

impacts of climate change on the United 

States, now and in the future. It focuses 

on climate change impacts in different 

regions of the U.S. and on various 

aspects of society and the economy such 

as energy, water, agriculture, and 

human health. It’s also a report written 

in plain language, with the goal of better 

informing public and private decision 

making at all levels. The foundation of 

this report is a set of 21 Synthesis and 

Assessment Products (SAPs), which 

were designed to address key policyrelevant issues in climate science. The 

report was extensively reviewed and 

revised based on comments from 

experts and the public. The report was 

approved by its lead USGCRP Agency, 

the National Oceanic and Atmospheric 

Administration, the other USGCRP 

agencies, and the Committee on the 

Environment and Natural Resources on 

behalf of the National Science and 

Technology Council. This report meets 

all Federal requirements associated with 

the Information Quality Act, including 

those pertaining to public comment and 

transparency. Readers are encouraged to 

review this report. 

The source document for the section 

below is the draft endangerment 

Technical Support Document (TSD). In 

192 U.S. EPA (2008) Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2006. EPA–430–R– 

08–005, Washington, DC. http://www.epa.gov/ 

climatechange/emissions/usgginv_archive.html. 

193 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.). Cambridge University 

Press, 2009. http://www.globalchange.gov/ 

publications/reports/scientific-assessments/usimpacts. 

EPA’s Proposed Endangerment and 

Cause or Contribute Findings Under the 

Clean Air Act,194 EPA provides a 

summary of the USGCRP and IPCC 

reports in a draft TSD. The draft TSD 

reviews observed and projected changes 

in climate based on current and 

projected atmospheric GHG 

concentrations and emissions, as well as 

the related impacts and risks from 

climate change that are projected in the 

absence of GHG mitigation actions, 

including this proposal and other U.S. 

and global actions. The TSD serves as an 

important support document to EPA’s 

proposed Endangerment Finding; 

however, the document is a draft and is 

still undergoing comment and review as 

part of EPA’s rulemaking process, and is 

subject to change based upon comments 

to the final endangerment finding. 

a. Changes in Atmospheric 

Concentrations of GHGs From Global 

and U.S. Emissions 

Concentrations of six key GHGs 

(carbon dioxide, methane, nitrous oxide, 

hydrofluorocarbons, perfluorocarbons 

and sulfur hexafluoride) are at 

unprecedented levels compared to the 

recent and distant past. The global 

atmospheric CO2 concentration has 

increased about 38% from pre-industrial 

levels to 2009, and almost all of the 

increase is due to anthropogenic 

emissions. 

Based on data from the most recent 

Inventory of U.S. Greenhouse Gas 

Emissions and Sinks (2008),195 total 

U.S. GHG emissions increased by 905.9 

teragrams of CO2-equivalent (Tg CO2 

Eq), or 14.7%, between 1990 and 2006. 

U.S. transportation sources subject to 

control under section 202(a) of the 

Clean Air Act (passenger cars, light duty 

trucks, other trucks and buses, 

motorcycles, and cooling 196) emitted 

1665 Tg CO2 Eq in 2006, representing 

almost 24% of the total U.S. GHG 

emissions. Total global emissions, 

calculated by summing emissions of the 

six greenhouse gases by country, for 

2005 was 38,725.9 Tg CO2 Eq. This 

represents an increase of 26% from the 

1990 level. See the EPA report 

‘‘Inventory of U.S. Greenhouse Gas 

Emissions and Sinks: 1990–2006’’,197 

194 See Federal Register/Vol. 74, No. 78/Friday, 

April 24, 2009/Proposed Rules; also Docket Number 

EPA–HQ–OAR–2009–0171; FRL–8895–5. 

195 U.S. EPA (2008) Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2006. EPA–430–R– 

08–005, Washington, DC. 

196 Cooling refers to refrigerants/air conditioning 

from all transportation sources and is related to 

HFCs. 

197 U.S. EPA (2008) Inventory of U.S. Greenhouse 

Gas Emissions and Sinks: 1990–2006. EPA–430–R– 

08–005, Washington, DC. http://www.epa.gov/ 

climatechange/emissions/usgginv_archive.html. 

Section 2 of the proposed Endangerment 

TSD, and IPCC’s Working Group I (WGI) 

Fourth Assessment Report (AR4) 198 for 

a more complete discussion of GHG 

emissions and concentrations. 

b. Observed Changes in Climate 

i. Temperature 

The warming of the climate system is 

unequivocal, as is now evident from 

observations of increases in global air 

and ocean temperatures, widespread 

melting of snow and ice, and rising 

global average sea level. The global 

average net effect of the increase in 

atmospheric GHG concentrations, plus 

other human activities (e.g., land use 

change and aerosol emissions), on the 

global energy balance since 1750 has 

been one of warming. The global mean 

surface temperature 199 over the last 100 

years (1906–2005) has risen by about 

0.74 °C (1.5 °F) +/¥ 0.18 °C, and climate 

model simulations suggest that natural 

variation alone (e.g., changes in solar 

irradiance) cannot explain the observed 

warming. The rate of warming over the 

last 50 years is almost double that over 

the last 100 years. Most of the observed 

increase in global mean surface 

temperature since the mid-20th century 

is very likely due to the observed 

increase in anthropogenic GHG 

concentrations. 

It can be stated with confidence that 

global mean surface temperature was 

higher during the last few decades of the 

20th century than during any 

comparable period during the preceding 

four centuries. Like global mean surface 

temperatures, U.S. surface temperatures 

also warmed during the 20th and into 

the 21st century. U.S. average annual 

temperatures are now approximately 

0.69°C (1.25°F) warmer than at the start 

of the 20th century, with an increased 

rate of warming over the past 30 years. 

Temperatures in winter have risen more 

than any other season, with winters in 

the Midwest and northern Great Plains 

increasing more than 7 °F.200 Some of 

these changes have been faster than 

previous assessments had suggested. 

For additional information, please see 

Section 4 of the proposed Endangerment 

198 Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, 

M.Tignor and H.L. Miller (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

199 Surface temperature is calculated by 

processing data from thousands of world-wide 

observation sites on land and sea. 

200 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.) Cambridge University 

Press, 2009. 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49585 

TSD, IPCC WGI AR4,201 and the report 

‘‘Global Climate Change Impacts in the 

United States’’.202 

ii. Precipitation 

Observations show that changes are 

occurring in the amount, intensity, 

frequency and type of precipitation. 

Global, long-term trends from 1900 to 

2005 have been observed in the amount 

of precipitation over many large regions. 

Patterns in precipitation change are 

more spatially and seasonally variable 

than temperature change, but where 

significant precipitation changes do 

occur they are consistent with measured 

changes in stream flow. Significantly 

increased precipitation has been 

observed in eastern parts of North and 

South America, northern Europe and 

northern and central Asia.200 More 

intense and longer droughts have been 

observed over wider areas since the 

1970s, particularly in the tropics and 

subtropics. It is likely there has been an 

increase in heavy precipitation events 

(e.g., 95th percentile) within many land 

regions, even in those where there has 

been a reduction in total precipitation 

amount, consistent with a warming 

climate and observed significant 

increasing amounts of water vapor in 

the atmosphere. Rising temperatures 

have generally resulted in rain rather 

than snow in locations and seasons such 

as in northern and mountainous regions 

where the average (1961–1990) 

temperatures were close to 0 °C. Over 

the contiguous U.S., total annual 

precipitation increased at an average 

rate of 6.5% from 1901–2006, with the 

greatest increases in precipitation in the 

East and North Central climate regions 

(11.2% per century). 

For additional information, please see 

Section 4 of the proposed Endangerment 

TSD, IPCC WGI AR4,203 and the 

201 Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, 

M.Tignor and H.L. Miller (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

202 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.). Cambridge University 

Press, 2009. http://www.globalchange.gov/ 

publications/reports/scientific-assessments/usimpacts. 

203 Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, 

M.Tignor and H.L. Miller (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

USGCRP report ‘‘Global Climate Change 

Impacts in the United States’’.204 

iii. Extreme Events 

Changes in climate extremes have 

been observed related to temperature, 

precipitation, tropical cyclones, and sea 

level. In the last 50 years, there have 

been widespread changes in extreme 

temperatures observed across the globe. 

For example, cold days, cold nights, and 

frost have become less frequent, while 

hot days, hot nights, and heat waves 

have become more frequent. Globally, a 

reduction in the number of daily cold 

extremes has been observed in 70 to 

75% of the land regions where data is 

available. Cold nights (lowest or coldest 

10% of nights, based on the period 

1961–1990) have become rarer over the 

last 50 years. 

Observational evidence indicates an 

increase in intense tropical cyclone (i.e., 

tropical storms and/or hurricanes) 

activity in the North Atlantic. Since 

about 1970, increases in cyclone 

developments that affect the U.S. East 

and Gulf Coasts have been correlated 

with increases of tropical sea surface 

temperatures In the contiguous U.S., 

studies find statistically significant 

increases in heavy precipitation (the 

heaviest 5%) and very heavy 

precipitation (the heaviest 1%) of 14 

and 20%, respectively. Much of this 

increase occurred during the last three 

decades of the 20th century and is most 

apparent over the eastern parts of the 

country. Trends in drought also have 

strong regional variations. In much of 

the Southeast and large parts of the 

western U.S., the frequency of drought 

has increased coincident with rising 

temperatures over the past 50 years. 

Although there has been an overall 

increase in precipitation and no clear 

trend in drought for the nation as a 

whole, increasing temperatures have 

made droughts more severe and 

widespread than they would have 

otherwise been. 

For additional information, please see 

Section 4 of the proposed Endangerment 

TSD, the CCSP report ‘‘Weather and 

Climate Extremes in a Changing 

Climate. Regions of Focus: North 

America, Hawaii, Caribbean, and U.S. 

204 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.). Cambridge University 

Press, 2009. http://www.globalchange.gov/ 

publications/reports/scientific-assessments/usimpacts. 

Pacific Islands’’,205 IPCC WGI AR4,206 

and the report ‘‘Global Climate Change 

Impacts in the United States’’.207 

iv. Physical and Biological Changes 

Observations show that climate 

change is currently affecting U.S. 

physical and biological systems in 

significant ways. Observations of the 

cryosphere (the ‘‘frozen’’ component of 

the climate system) have revealed 

changes in sea ice, glaciers and snow 

cover, freezing and thawing, and 

permafrost. Satellite data since 1978 

show that annual average Arctic sea ice 

extent has shrunk by 2.7% (+/¥ 0.6%) 

per decade, with larger decreases in 

summer. Subtropical and tropical corals 

in shallow waters have already suffered 

major bleaching events that are 

primarily driven by increases in sea 

surface temperatures. Heat stress from 

warmer ocean water can cause corals to 

expel the microscopic algae that live 

inside them which are essential to their 

survival. Another stressor on coral 

populations is ocean acidification 

which occurs as CO2 is absorbed from 

the atmosphere by the oceans. About 

one-third of the carbon dioxide emitted 

by human activities has been absorbed 

by the ocean, resulting in a decrease in 

the ocean’s pH. A lower pH affects the 

ability of living things to create and 

maintain shells or skeletons of calcium 

carbonate. Other documented biophysical impacts include a significant 

lengthening of the growing season and 

increase in net primary productivity 208 

in higher latitudes of North America. 

Over the last 19 years, global satellite 

data indicate an earlier onset of spring 

across the temperate latitudes by 10 to 

14 days. 

205 Weather and Climate Extremes in a Changing 

Climate. Regions of Focus: North America, Hawaii, 

Caribbean, and U.S. Pacific Islands. A Report by 

the U.S. Climate Change Science Program and the 

Subcommittee on Global Change Research. [Thomas 

R. Karl, Gerald A. Meehl, Christopher D. Miller, 

Susan J. Hassol, Anne M. Waple, and William L. 

Murray (eds.)]. Department of Commerce, NOAA’s 

National Climatic Data Center, Washington, D.C., 

USA, 164 pp. 

206 Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, 

M.Tignor and H.L. Miller (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

207 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.). Cambridge University 

Press, 2009. http://www.globalchange.gov/ 

publications/reports/scientific-assessments/usimpacts. 

208 Net primary productivity is the rate at which 

an ecosystem accumulates energy or biomass, 

excluding the energy it uses for the process of 

respiration. 
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49586 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

For additional information, please see 

Section 4 of the proposed Endangerment 

TSD and IPCC WGI AR4.209 

c. Projected Changes in Climate 

Most future scenarios that assume no 

explicit GHG mitigation actions (beyond 

those already enacted) project 

increasing global GHG emissions over 

the century, with corresponding 

climbing GHG concentrations. Carbon 

dioxide is expected to remain the 

dominant anthropogenic GHG over the 

course of the 21st century. The radiative 

forcing 210 associated with the non-CO2 

GHGs is still significant and increasing 

over time. As a result, warming over this 

century is projected to be considerably 

greater than over the last century and 

climate related changes are expected to 

continue while new ones develop. 

Described below are projected changes 

in climate for the U.S. 

See Section 6 of the proposed 

Endangerment TSD, IPCC WGI AR4,211 

the USGCRP report ‘‘Global Climate 

Change Impacts in the United 

States’’,212 and the CCSP report 

‘‘Weather and Climate Extremes in a 

Changing Climate, Regions of Focus: 

North America, Hawaii, Caribbean, and 

U.S. Pacific Islands’’ 213 for a more 

complete discussion of projected 

changes in climate. 

209 IPCC (2007a) Climate Change 2007: The 

Physical Science Basis. Contribution of Working 

Group I to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change 

[Solomon, S., D. Qin, M. Manning, Z. Chen, M. 

Marquis, K.B. Averyt, M. Tignor and H.L. Miller 

(eds.)]. Cambridge University Press, Cambridge, 

United Kingdom and New York, NY, USA. 

210 Radiative forcing is a measure of the change 

that a factor causes in altering the balance of 

incoming (solar) and outgoing (infrared and 

reflected shortwave) energy in the Earth-atmosphere 

system and thus shows the relative importance of 

different factors in terms of their contribution to 

climate change. 

211 Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, 

M.Tignor and H.L. Miller (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

212 Global Climate Change Impacts in the United 

States, Thomas R. Karl, Jerry M. Melillo, and 

Thomas C. Peterson, (eds.). Cambridge University 

Press, 2009. http://www.globalchange.gov/ 

publications/reports/scientific-assessments/usimpacts. 

213 Weather and Climate Extremes in a Changing 

Climate. Regions of Focus: North America, Hawaii, 

Caribbean, and U.S. Pacific Islands. A Report by 

the U.S. Climate Change Science Program and the 

Subcommittee on Global Change Research. [Thomas 

R. Karl, Gerald A. Meehl, Christopher D. Miller, 

Susan J. Hassol, Anne M. Waple, and William L. 

Murray (eds.)]. Department of Commerce, NOAA’s 

National Climatic Data Center, Washington, DC, 

USA, 164 pp. 

i. Temperature 

Future warming over the course of the 

21st century, even under scenarios of 

low emissions growth, is very likely to 

be greater than observed warming over 

the past century. The range of IPCC 

SRES scenarios provides a global 

warming range of 1.8 °C to 4.0 °C (3.2 

°F to 7.2 °F) with an uncertainty range 

of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F). 

All of the U.S. is very likely to warm 

during this century, and most areas of 

the U.S. are expected to warm by more 

than the global average. The average 

warming in the U.S. through 2100 is 

projected by nearly all the models used 

in the IPCC assessment to exceed 2 °C 

(3.6 °F) for all scenarios, with 5 out of 

21 models projecting average warming 

in excess of 4 °C (7.2 °F) for the midrange emissions scenario. The number 

of days with high temperatures above 90 

°F is projected to increase throughout 

the U.S. Temperature increases in the 

next couple of decades will be primarily 

determined by past emissions of heattrapping gases. As a result, there is less 

difference in projected temperature 

scenarios in the near-term (around 2020) 

than in the middle (2050) and end of the 

century, which will be determined more 

by future emissions. 

ii. Precipitation 

Increases in the amount of 

precipitation are very likely in higher 

latitudes, while decreases are likely in 

most subtropical latitudes and the 

southwestern U.S., continuing observed 

patterns. The mid-continental area is 

expected to experience drying during 

the summer, indicating a greater risk of 

drought. Climate models project 

continued increases in the heaviest 

downpours during this century, while 

the lightest precipitation is projected to 

decrease. With more intense 

precipitation expected to increase, the 

risk of flooding and greater runoff and 

erosion will also increase. In contrast, 

droughts are likely to become more 

frequent and severe in some regions. 

The Southwest, in particular, is 

expected to experience increasing 

drought as changes in atmospheric 

circulation patterns cause the dry zone 

just outside the tropics to expand farther 

northward into the United States. 

iii. Extreme Events 

It is likely that hurricanes will 

become more intense, especially along 

the Gulf and Atlantic coasts, with 

stronger peak winds and more heavy 

precipitation associated with ongoing 

increases of tropical sea surface 

temperatures. Heavy rainfall events are 

expected to increase, increasing the risk 

of flooding, greater runoff and erosion, 

and thus the potential for adverse water 

quality effects. These projected trends 

can increase the number of people at 

risk from suffering disease and injury 

due to floods, storms, droughts, and 

fires. Severe heat waves are projected to 

intensify, which can increase heatrelated mortality and sickness. 

iv. Physical and Biological Changes 

IPCC projects a six-inch to two-foot 

rise in sea level during the 21st century 

from processes such as thermal 

expansion of sea water and the melting 

of land-based polar ice sheets. Ocean 

acidification is projected to continue, 

resulting in the reduced biological 

production of marine calcifiers, 

including corals. In addition to ocean 

acidification, coastal waters are very 

likely to continue to warm by as much 

as 4 to 8 °F in this century, both in 

summer and winter. This will result in 

a northward shift in the geographic 

distribution of marine life along the 

coasts. Warmer ocean temperatures will 

also contribute to increased coral 

bleaching. 

d. Key Climate Change Impacts and 

Risks 

The effects of climate changes 

observed to date and/or projected to 

occur in the future include: More 

frequent and intense heat waves, more 

wildfires, degraded air quality, more 

heavy downpours and flooding, 

increased drought, greater sea level rise, 

more intense storms, water quantity and 

quality problems, and negative impacts 

to human health, water supply, 

agriculture, forestry, coastal areas, 

wildlife and ecosystems, and many 

other aspects of society and the natural 

environment. 

i. Human Health 

Warm temperatures and extreme 

weather already cause and contribute to 

adverse human health outcomes 

through heat-related mortality and 

morbidity, storm-related fatalities and 

injuries, and disease. In the absence of 

effective adaptation, these effects are 

likely to increase with climate change. 

Health effects related to climate change 

include increased deaths, injuries, 

infectious diseases, and stress-related 

disorders and other adverse effects 

associated with social disruption and 

migration from more frequent extreme 

weather. Severe heat waves are 

projected to intensify in magnitude and 

duration over the portions of the U.S. 

where these events already occur, with 

potential increases in mortality and 

morbidity, especially among the elderly, 

young and other sensitive populations. 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49587 

However, reduced human mortality 

from cold exposure is projected through 

2100. It is not clear whether reduced 

mortality from cold will be greater or 

less than increased heat-related 

mortality, especially among the elderly, 

young and frail. Public health effects 

from climate change will likely 

disproportionately impact the health of 

certain segments of the population, such 

as the poor, the very young, the elderly, 

those already in poor health, the 

disabled, those living alone and/or 

indigenous populations dependent on 

one or a few resources. Increases are 

expected in potential ranges and 

exposure of certain diseases affected by 

temperature and precipitation changes, 

including vector and waterborne 

diseases (i.e., malaria, dengue fever, 

West Nile virus). See the CCSP Report 

‘‘Analyses of the effects of global change 

on human health and welfare and 

human systems’’,214 IPCC’s Working 

Group II (WG2) AR4,215 and Section 7 

of the proposed Endangerment TSD for 

a more complete discussion regarding 

climate change and impacts on human 

health. 

ii. Air Quality 

Climate change can be expected to 

influence the concentration and 

distribution of air pollutants through a 

variety of direct and indirect processes, 

including the modification of biogenic 

emissions, the change of chemical 

reaction rates, wash-out of pollutants by 

precipitation, and modification of 

weather patterns that influence 

pollutant build-up. Higher temperatures 

and weaker circulation patterns 

associated with climate change are 

expected to worsen regional ozone 

pollution in the U.S., with associated 

risks in respiratory infection, 

aggravation of asthma, and premature 

death. In addition to human health 

effects, elevated levels of tropospheric 

ozone have significant adverse effects 

on crop yields, pasture and forest 

growth, and species composition. See 

Section 8 of the proposed Endangerment 

TSD, EPA’s report ‘‘Assessment of the 

Impacts of Global Change on Regional 

U.S. Air Quality: A Synthesis of Climate 

214 Analyses of the effects of global change on 

human health and welfare and human systems. A 

Report by the U.S. Climate Change Science Program 

and the Subcommittee on Global Change Research. 

[Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. 

Wilbanks, (Authors)]. U.S. Environmental 

Protection Agency, Washington, DC, USA. 

215 Climate Change 2007: Impacts, Adaptation 

and Vulnerability. Contribution of Working Group 

II to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change [M.L. 

Parry, O.F. Canziani, J.P. Palutikof, P.J. van der 

Linden and C.E. Hanson (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

Change Impacts on Ground-Level 

Ozone’’, 216 the CCSP report ‘‘Analyses 

of the effects of global change on human 

health and welfare and human 

systems’’ 217 and IPCC WGII AR4 218 for 

a more complete discussion regarding 

human health impacts resulting from 

climate change effects on air quality. 

iii. Food and Agriculture 

The CCSP concluded that, with 

increased CO2 and temperature, the life 

cycle of grain and oilseed crops will 

likely progress more rapidly. But, as 

temperature rises, these crops will 

increasingly begin to experience failure, 

especially if climate variability 

increases and precipitation lessens or 

becomes more variable. Furthermore, 

the marketable yield of many 

horticultural crops (e.g., tomatoes, 

onions, fruits) is very likely to be more 

sensitive to climate change than grain 

and oilseed crops. Higher temperatures 

will very likely reduce livestock 

production during the summer season, 

but these losses will very likely be 

partially offset by warmer temperatures 

during the winter season. Cold water 

fisheries will likely be negatively 

affected; warm-water fisheries will 

generally benefit; and the results for 

cool-water fisheries will be mixed, with 

gains in the northern and losses in the 

southern portions of ranges. See Section 

9 of the proposed Endangerment TSD, 

the CCSP report ‘‘The Effects of Climate 

Change on Agriculture, Land Resources, 

Water Resources, and Biodiversity in 

the United States’’, and the USGCRP 

report ‘‘Global Climate Change Impacts 

in the United States’’ for a more 

complete discussion regarding climate 

science and impacts to food production 

and agriculture. 

iv. Forestry 

Climate change has very likely 

increased the size and number of forest 

fires, insect outbreaks, and tree 

216 EPA (2009) Assessment of the Impacts of 

Global Change on Regional U.S. Air Quality: A 

Synthesis of Climate Change Impacts on GroundLevel Ozone. An Interim Report of the U.S. EPA 

Global Change Research Program. U.S. 

Environmental Protection Agency, Washington, DC, 

EPA/600/R–07/094. 

217 Analyses of the effects of global change on 

human health and welfare and human systems. A 

Report by the U.S. Climate Change Science Program 

and the Subcommittee on Global Change Research. 

[Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. 

Wilbanks, (Authors)]. U.S. Environmental 

Protection Agency, Washington, DC, USA. 

218 Climate Change 2007: Impacts, Adaptation 

and Vulnerability. Contribution of Working Group 

II to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change [M.L. 

Parry, O.F. Canziani, J.P. Palutikof, P.J. van der 

Linden and C.E. Hanson (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and 

New York, NY, USA. 

mortality in the interior west, the 

Southwest, and Alaska, and will 

continue to do so. Disturbances like 

wildfire and insect outbreaks are 

increasing and are likely to intensify in 

a warmer future with drier soils and 

longer growing seasons. Although recent 

climate trends have increased vegetation 

growth, continuing increases in 

disturbances are likely to limit carbon 

storage, facilitate invasive species, and 

disrupt ecosystem services. Overall 

forest growth for North America as a 

whole will likely increase modestly (10– 

20%) as a result of extended growing 

seasons and elevated CO2 over the next 

century, but with important spatial and 

temporal variation. Forest growth is 

slowing in areas subject to drought and 

has been subject to significant loss due 

insect infestations such as the spruce 

bark beetle in Alaska. See Section 10 of 

the proposed Endangerment TSD, the 

CCSP report ‘‘The Effects of Climate 

Change on Agriculture, Land Resources, 

Water Resources, and Biodiversity in 

the United States’’, IPCC WGII, and the 

USGCRP report ‘‘Global Climate Change 

Impacts in the United States’’ for a more 

complete discussion regarding climate 

science and impacts to forestry. 

v. Water Resources 

The vulnerability of freshwater 

resources in the United States to climate 

change varies from region to region. 

Climate change will likely further 

constrain already over-allocated water 

resources in some sections of the U.S., 

increasing competition among 

agricultural, municipal, industrial, and 

ecological uses. Although water 

management practices in the U.S. are 

generally advanced, particularly in the 

western U.S climate change may 

increasingly create conditions well 

outside of historic observations 

impacting managed water systems. 

Rising temperatures will diminish 

snowpack and increase evaporation, 

affecting seasonal availability of water. 

Groundwater systems generally respond 

more slowly to climate change than 

surface water systems. In semi-arid and 

arid areas, groundwater resources are 

particularly vulnerable because of 

precipitation and stream flow are 

concentrated over a few months, yearto-year variability is high, and deep 

groundwater wells or reservoirs 

generally do not exist. Availability of 

groundwater is likely to be influenced 

by changes in withdrawals (reflecting 

development, demand, and availability 

of other sources). 

In the Great Lakes and major river 

systems, lower levels are likely to 

exacerbate challenges relating to water 

quality, navigation, recreation, 
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49588 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

hydropower generation, water transfers, 

and bi-national relationships. Decreased 

water supply and lower water levels are 

likely to exacerbate challenges relating 

to aquatic navigation. Higher water 

temperatures, increased precipitation 

intensity, and longer periods of low 

flows will exacerbate many forms of 

water pollution, potentially making 

attainment of water quality goals more 

difficult. As waters become warmer, the 

aquatic life they now support will be 

replaced by other species better adapted 

to warmer water. In the long-term, 

warmer water and changing flow may 

result in deterioration of aquatic 

ecosystems. See Section 11 of the 

proposed Endangerment TSD, the CCSP 

report ‘‘The Effects of Climate Change 

on Agriculture, Land Resources, Water 

Resources, and Biodiversity in the 

United States’’, IPCC WGII, and the 

USGCRP report ‘‘Global Change Impacts 

in the United States’’ for a more 

complete discussion regarding climate 

science and impacts to water resources. 

vi. Sea Level Rise and Coastal Areas 

Warmer temperatures raise sea level 

by expanding ocean water, melting 

glaciers, and possibly increasing the rate 

at which ice sheets discharge ice and 

water into the oceans. Rising sea level 

and the potential for stronger storms 

pose an increasing threat to coastal 

cities, residential communities, 

infrastructure, beaches, wetlands, and 

ecosystems. Coastal communities and 

habitats will be increasingly stressed by 

climate change effects interacting with 

development and pollution. Sea level is 

rising along much of the U.S. coast, and 

the rate of change will increase in the 

future, exacerbating the impacts of 

progressive inundation, storm-surge 

flooding, and shoreline erosion. Studies 

find 75% of the shoreline removed from 

the influence of spits, tidal inlets and 

engineering structures is eroding along 

the U.S. East Coast probably due to sea 

level rise. Storm impacts are likely to be 

more severe, especially along the Gulf 

and Atlantic coasts. Salt marshes, 

estuaries, other coastal habitats, and 

dependent species will be further 

threatened by sea level rise. The 

interaction with coastal zone 

development and climate change effects 

such as sea level rise will further stress 

coastal communities and habitats. 

Population growth and rising value of 

infrastructure in coastal areas increases 

vulnerability and risk of climate 

variability and future climate change. 

Sea level rise and high rates of water 

withdrawal promote the intrusion of 

saline water in to groundwater supplies, 

which adversely affects water quality. 

See Section 12 of the proposed 

Endangerment TSD, the CCSP report 

‘‘Coastal Sensitivity to Sea Level Rise: A 

Focus on the Mid-Atlantic Region’’,219 

the USGCRP report ‘‘Global Change 

Impacts in the United States’’, and IPCC 

WGII for a more complete discussion 

regarding climate science and impacts 

to sea level rise and coastal areas. 

vii. Energy, Infrastructure and 

Settlements 

Most of the effects of climate change 

on the U.S. energy sector will be related 

to energy use and production. The 

research evidence is relatively clear that 

climate warming will mean reductions 

in total U.S. heating requirements and 

increases in total cooling requirements 

for building. These changes will vary by 

region and by season and will affect 

household and business energy costs. 

Studies project that temperature 

increases due to global warming are 

very likely to increase peak demand for 

electricity in most regions of the country 

as rising temperatures are expected to 

increase energy requirements for cooling 

residential and commercial buildings. 

An increase in peak demand for 

electricity can lead to a disproportionate 

increase in energy infrastructure 

investment. Extreme weather events can 

threaten coastal energy infrastructures 

and electricity transmission and 

distribution in the U.S. Increases in 

hurricane intensity are likely to cause 

further disruptions to oil and gas 

operations in the Gulf, like those 

experienced in 2005 with Hurricane 

Katrina. Climate change is likely to 

affect some renewable energy sources 

across the nation, such as hydropower 

production in regions subject to 

changing patterns of precipitation or 

snowmelt. The U.S. energy sector, 

which relies heavily on water for both 

hydropower and cooling capacity, may 

be adversely impacted by changes to 

water supply and quality in reservoirs 

and other water bodies. 

Water infrastructure, including 

drinking water and wastewater 

treatment plants, and sewer and storm 

water management systems, will be at 

greater risk of flooding, sea level rise 

and storm surge, low flows, and other 

factors that could impair performance. 

In addition, as water supply is 

constrained and demand increases it 

will become more likely that water will 

219 CCSP (2009) Coastal Sensitivity to Sea-Level 

Rise: A Focus on the Mid-Atlantic Region. A report 

by the U.S. Climate Change Science Program and 

the Subcommittee on Global Change Research. 

[James G. Titus (Coordinating Lead Author), K. Eric 

Anderson, Donald R. Cahoon, Dean B. Gesch, 

Stephen K. Gill, Benjamin T. Gutierrez, E. Robert 

Thieler, and S. Jeffress Williams (Lead Authors)], 

U.S. Environmental Protection Agency, Washington 

DC, USA, 320 pp. 

have to be transported and moved 

which will require additional energy 

capacity. See Section 13 of the proposed 

Endangerment TSD, the CCSP reports 

‘‘the Effects of Climate Change on 

Energy Production in the United 

States’’ 220 and ‘‘Impacts of Climate 

Change and Variability on 

Transportation Systems and 

Infrastructure’’,221 and the USGCRP 

report ‘‘Global Change Impacts in the 

United States’’ for a more complete 

discussion regarding climate science 

and impacts to energy, infrastructure 

and settlements. 

viii. Ecosystems and Wildlife 

Disturbances such as wildfires and 

insect outbreaks are increasing in the 

U.S. and are likely to intensify in a 

warmer future with drier soils and 

longer growing seasons. Although recent 

climate trends have increased vegetation 

growth, continuing increases in 

disturbances are likely to limit carbon 

storage, facilitate invasive species, and 

disrupt ecosystem services. Over the 

21st century, changes in climate will 

cause species to shift north and to 

higher elevations and fundamentally 

rearrange U.S. ecosystems. Differential 

capacities for range shifts are 

constrained by development, habitat 

fragmentation, invasive species, and 

broken ecological connections. IPCC 

consequently predicts significant 

disruption of ecosystem structure, 

function, and services. See Section 14 of 

the proposed Endangerment TSD, IPCC 

WGII, the CCSP report ‘‘The Effects of 

Climate Change on Agriculture, Land 

Resources, Water Resources, and 

Biodiversity in the United States’’, and 

the USGCRP report ‘‘Global Change 

Impacts in the United States’’ for a more 

complete discussion regarding climate 

science and impacts to ecosystems and 

wildlife. 

220 CCSP (2007): Effects of Climate Change on 

Energy Production and Use in the United States. A 

Report by the U.S. Climate Change Science Program 

and the subcommittee on Global Change Research. 

Thomas J. Wilbanks, Vatsal Bhatt, Daniel E. Bilello, 

Stanley R. Bull, James Ekmann, William C. Horak, 

Y. Joe Huang, Mark D. Levine, Michael J. Sale, 

David K. Schmalzer, and Michael J. Scott). 

Department of Energy, Office of Biological & 

Environmental Research, Washington, DC, USA, 

160 pp. 

221 CCSP (2008) Impacts of Climate Change and 

Variability on Transportation Systems and 

Infrastructure: Gulf Coast Study, Phase I. A Report 

by the U.S. Climate Change Science Program and 

the Subcommittee on Global Change Research 

[Savonis, M.J., V.R. Burkett, and J.R. Potter (eds.)]. 

Department of Transportation, Washington, DC, 

USA, 445 pp. 
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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49589 

3. Changes in Global Mean Temperature 

and Sea Level Rise Associated With the 

Proposal’s GHG Emissions Reductions 

EPA examined 222 the reductions in 

CO2 and other GHGs associated with the 

proposal and analyzed the projected 

effects on global mean surface 

temperature and sea level, two common 

indicators of climate change. The 

analysis projects that the proposal will 

reduce climate warming and sea level 

rise. Although the projected reductions 

are small in overall magnitude by 

themselves, they are quantifiable and 

would contribute to reducing climate 

change risks. 

a. Estimated Projected Reductions in 

Global Mean Surface Temperatures and 

Sea Level Rise 

EPA estimated changes in the 

atmospheric CO2 concentration, global 

mean surface temperature and sea level 

to 2100 resulting from the emissions 

reductions in this proposal using the 

Model for the Assessment of 

Greenhouse Gas Induced Climate 

Change (MAGICC, version 5.3). This 

widely used, peer reviewed modeling 

tool was also used to project 

temperature and sea level rise under 

different emissions scenarios in the 

Third and Fourth Assessments of the 

Intergovernmental Panel on Climate 

Change (IPCC). 

GHG emissions reductions from 

Section III.F.1a were applied as net 

reductions to a peer reviewed global 

reference case (or baseline) emissions 

scenario to generate an emissions 

scenario specific to this proposal. For 

the proposal scenario, all emissions 

reductions were assumed to begin in 

2012, with zero emissions change in 

2011 (from the reference case) followed 

by emissions linearly increasing to 

equal the value supplied in Section 

III.F.1.a for 2020 and then continuing to 

2100. Details about the reference case 

scenario and how the emissions 

reductions were applied to generate the 

proposal scenario can be found in the 

DRIA Chapter 7. 

The atmospheric CO2 concentration, 

temperature, and sea-level increases for 

both the reference case and the proposal 

emissions scenarios were computed 

using MAGICC. To compute the 

reductions in the atmospheric CO2 

concentrations as well as in temperature 

and sea level resulting from the 

proposal, the output from the proposal 

222 Using the Model for the Assessment of 

Greenhouse Gas Induced Climate Change (MAGICC, 

http://www.cgd.ucar.edu/cas/wigley/magicc/), EPA 

estimated the effects of this action’s greenhouse gas 

emissions reductions on global mean temperature 

and sea level. Please refer to Chapter 7.4 of the 

DRIA for additional information. 

scenario was subtracted from an existing 

MiniCAM emission scenario. To capture 

some key uncertainties in the climate 

system with the MAGICC model, 

changes in temperature and sea-level 

rise were projected across the most 

current IPCC range for climate 

sensitivities which ranges from 1.5 °C to 

6.0 °C (representing the 90% confidence 

interval).223 This wide range reflects the 

uncertainty in this measure of how 

much the global mean temperature 

would rise if the concentration of 

carbon dioxide in the atmosphere were 

to double. Details about this modeling 

analysis can be found in the DRIA 

Chapter 7.4. 

The results of this modeling show 

small, but quantifiable, reductions in 

the atmospheric CO2 concentration, the 

projected global mean surface 

temperature and sea level resulting from 

this proposal (assuming it is finalized), 

across all climate sensitivities. As a 

result of this proposal’s emission 

reductions, the atmospheric CO2 

concentration is projected to be reduced 

by approximately 2.9 to 3.2 parts per 

million (ppm), the global mean 

temperature is projected to be reduced 

by approximately 0.007–0.016 °C by 

2100, and global mean sea level rise is 

projected to be reduced by 

approximately 0.06–0.15cm by 2100. 

The reductions are small relative to the 

IPCC’s 2100 ‘‘best estimates’’ for global 

mean temperature increases (1.8–4.0 °C) 

and sea level rise (0.20–0.59m) for all 

global GHG emissions sources for a 

range of emissions scenarios. EPA used 

a peer reviewed model, the MAGICC 

model, to do this analysis. This analysis 

is specific to the proposed rule and 

therefore cannot come from some 

previously published work. The Agency 

welcomes comment on the use of the 

MAGICC model for these purposes. 

Further discussion of EPA’s modeling 

analysis is found in Chapter 7 of the 

Draft RIA. 

As a substantial portion of CO2 

emitted into the atmosphere is not 

removed by natural processes for 

millennia, each unit of CO2 not emitted 

into the atmosphere avoids essentially 

permanent climate change on centennial 

time scales. Though the magnitude of 

the avoided climate change projected 

223 In IPCC reports, equilibrium climate 

sensitivity refers to the equilibrium change in the 

annual mean global surface temperature following 

a doubling of the atmospheric equivalent carbon 

dioxide concentration. The IPCC states that climate 

sensitivity is ‘‘likely’’ to be in the range of 2 °C to 

4.5 °C, ‘‘very unlikely’’ to be less than 1.5 °C, and 

‘‘values substantially higher than 4.5 °C cannot be 

excluded.’’ IPCC WGI, 2007, Climate Change 

2007—The Physical Science Basis, Contribution of 

Working Group I to the Fourth Assessment Report 

of the IPCC, http://www.ipcc.ch/. 

here is small, these reductions would 

represent a reduction in the adverse 

risks associated with climate change 

(though these risks were not formally 

estimated for this proposal) across all 

climate sensitivities. 

4. Weight Reduction and Potential 

Safety Impacts 

In this section, EPA will discuss 

potential safety impacts of the proposed 

standards. In the joint technology 

analysis, EPA and NHTSA agree that 

automakers could reduce weight as one 

part of the industry’s strategy for 

meeting the proposed standards. As 

shown in table III.D.6–3, of this 

Preamble, EPA’s modeling projects that 

vehicle manufacturers will reduce the 

weight of their vehicles by 4% on 

average between 2011 and 2016 

although individual vehicles may have 

greater or smaller weight reduction 

(NHTSA’s results are similar using the 

Volpe model). The penetration and 

magnitude of these modeled changes are 

consistent with the public 

announcements made by many 

manufacturers since early 2008 and are 

consistent with meetings that EPA has 

had with senior engineers and technical 

leadership at many of the automotive 

companies during 2008 and 2009. 

EPA also projects that automakers 

will not reduce footprint in order to 

meet the proposed CO2 standards in our 

modeling analysis. NHTSA and EPA 

have taken two measures to help ensure 

that the proposed rules provide no 

incentive for mass reduction to be 

accompanied by a corresponding 

decrease in the footprint of the vehicle 

(with its concomitant decrease in crush 

and crumple zones). The first design 

feature of the proposed rule is that the 

CO2 or fuel economy targets are based 

on the attribute of footprint (which is a 

surrogate for vehicle size).224 The 

second design feature is that the shape 

of the footprint curve (or function) has 

been carefully chosen such that it 

neither encourages manufacturers to 

increase, nor decrease the footprint of 

their fleet. Thus, the standard curves are 

designed to be approximately ‘‘footprint 

neutral’’ within the sloped portion of 

the function.225 For further discussion 

on this, refer to Section II.C of the 

preamble, or Chapter 2 of the joint TSD. 

Thus the agencies are assuming in their 

224 As the footprint attribute is defined as 

wheelbase times track width, the footprint target 

curves do not discourage manufacturers from 

reducing vehicle size by reducing front, rear, or side 

overhang, which can impact safety by resulting in 

less crush space. 

225 This neutrality with respect to footprint does 

not extend to the smallest and largest vehicles, 

because the function is limited, or flattened, in 

these footprint ranges. 
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49590 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

modeling analysis that the 

manufacturers could reduce vehicle 

mass without reducing vehicle footprint 

as one way to respond to the proposed 

rule.226 

In Section IV of this preamble, 

NHTSA presents a safety analysis of the 

proposed CAFE standards based on the 

2003 Kahane analysis. As discussed in 

Section IV, NHTSA has developed a 

worse case estimate of the impact of 

weight reductions on fatalities. The 

underlying data used for that analysis 

does not allow NHTSA to analyze the 

specific impact of weight reduction at 

constant footprint because historically 

there have not been a large number of 

vehicles produced that relied 

substantially on material substitution. 

Rather, the data set includes vehicles 

that were either smaller and lighter or 

larger and heavier. The numbers in the 

NHTSA analysis predict the safetyrelated fatality consequences that would 

occur in the unlikely event that weight 

reduction for model years 2012–2016 is 

accomplished by reducing mass and 

reducing footprint. EPA concurs with 

NHTSA that the safety analysis 

conducted by NHTSA and presented in 

Section IV is a worst case analysis for 

fatalities, and that the actual impacts on 

vehicle safety could be much less. 

However, EPA and NHTSA are not able 

to quantify the lower-bound potential 

impacts at this time. 

The agencies believe that reducing 

vehicle mass without reducing the size 

of the vehicle or the structural integrity 

is technically feasible in the rulemaking 

time frame. Many of the technical 

options for doing so are outlined in 

Chapter 3 of the joint TSD and in EPA’s 

DRIA. Weight reduction can be 

accomplished by the proven methods 

described below. Every manufacturer 

will employ these methodologies to 

some degree, the magnitude to which 

each will be used will depend on 

opportunities within individual vehicle 

design. 

• Material Substitution: Substitution 

of lower density and/or higher strength 

materials in a manner that preserves or 

improves the function of the 

component. This includes substitution 

of high-strength steels, aluminum, 

magnesium or composite materials for 

components currently fabricated from 

mild steel (e.g., the magnesium-alloy 

front structure used on the 2009 Ford 

F150 pickups).227 Light-weight 

226 See Chapter 1 of the joint TSD for a 

description of potential footprint changes in the 

2016 reference fleet. 

227 We note that since these MY 2009 F150s have 

only begun to enter the fleet, there is little realworld crash data available to evaluate the safety 

impacts of this new design. 

materials with acceptable energy 

absorption properties can maintain 

structural integrity and absorption of 

crash energy relative to previous designs 

while providing a net decrease in 

component weight. 

• Smart Design: Computer aided 

engineering (CAE) tools can be used to 

better optimize load paths within 

structures by reducing stresses and 

bending moments without adversely 

affecting structural integrity. This 

allows better optimization of the 

sectional thicknesses of structural 

components to reduce mass while 

maintaining or improving the function 

of the component. Smart designs also 

integrate separate parts in a manner that 

reduces mass by combining functions or 

the reduced use of separate fasteners. In 

addition, some ‘‘body on frame’’ 

vehicles are redesigned with a lighter 

‘‘unibody’’ construction with little 

compromise in vehicle functionality. 

• Reduced Powertrain Requirements: 

Reducing vehicle weight sufficiently 

can allow for the use of a smaller, 

lighter and more efficient engine while 

maintaining or even increasing 

performance. Approximately half of the 

reduction is due to these reduced 

powertrain output requirements from 

reduced engine power output and/or 

displacement, lighter weight 

transmission and final drive gear ratios. 

The subsequent reduced rotating mass 

(e.g. transmission, driveshafts/ 

halfshafts, wheels and tires) via weight 

and/or size reduction of components are 

made possible by reduced torque output 

requirements. 

• Mass Compounding: Following 

from the point above, the compounded 

weight reductions of the body, engine 

and drivetrain can reduce stresses on 

the suspension components, steering 

components, brakes, and thus allow 

further reductions in the weight of these 

subsystems. The reductions in weight 

for unsprung masses such as brakes, 

control arms, wheels and tires can 

further reduce stresses in the 

suspension mounting points which can 

allow still further reductions in weight. 

For example, lightweighting can allow 

for the reduction in the size of the 

vehicle brake system, while maintaining 

the same stopping distance. 

Therefore, EPA believes it is both 

technically feasible to reduce weight 

without reducing vehicle size, footprint 

or structural strength and manufacturers 

have indicated to the agencies that they 

will use these approaches to accomplish 

these tasks. We request written 

comment on this assessment and this 

projection, including up-to-date plans 

regarding the extent of use by each 

manufacturer of each of the 

methodologies described above. 

For this proposed rule, as noted 

earlier, EPA’s modeling analysis 

projects that weight reduction by model 

year 2016 on the order of 4% on average 

for the fleet will occur (see Section 

III.D.6 for details on our estimated mass 

reduction). EPA believes that such 

modeled changes in the fleet could 

result in much smaller fatality impacts 

than those in the worst case scenario 

presented in Section IV by NHTSA, 

since manufacturers have many safer 

options for reducing vehicle weight than 

doing so by simultaneously reducing 

footprint. The NHTSA analysis, based 

solely on 4-door vehicles, does not 

independently differentiate between 

weight reduction which comes from 

vehicle downsizing (a physically 

smaller vehicle) and vehicle weight 

reduction solely through design and 

material changes (i.e., making a vehicle 

weigh less without changing the size of 

the vehicle or reducing structural 

integrity). 

Dynamic Research Incorporated (DRI) 

has assessed the independent effects of 

vehicle weight and size on safety in 

order to determine if there are tradeoffs 

between improving vehicle safety and 

fuel consumption. In their 2005 

studies 228 229 one of which was 

published as a Society of Automotive 

Engineers Technical Paper and received 

peer review through that body, DRI 

presented results that indicate that 

vehicle weight reduction tends to 

decrease fatalities, but vehicle 

wheelbase and track reduction tends to 

increase fatalities. The DRI work 

focused on four major points, with #1 

and #4 being discussed with additional 

detail below: 

1. 2–Door vehicles represented a 

significant portion of the light duty fleet 

and should not be ignored. 

2. Directional control and therefore 

crash avoidance improves with a 

reduction in curb weight. 

3. The occupants of the impacted 

vehicle, or ‘‘collision partner’’ benefit 

from being impacted by a lighter 

vehicle. 

4. Rollover fatalities are reduced by a 

reduction in curb weight due to lower 

centers of gravity and lower loads on the 

roof structures. 

228 ‘‘Supplemental Results on the Independent 

Effects of Curb Weight, Wheelbase and Track on 

Fatality Risk’’, Dynamic Research, Inc., DRI–TR– 

05–01, May 2005. 

229 ‘‘An Assessment of the Effects of Vehicle 

Weight and Size on Fatality Risk in 1985 to 1998 

Model Year Passenger Cars and 1985 to 1997 Model 

Year’’, M. Van Auken and J. Zellner, Dynamic 

Research Inc., Society of Automotive Engineers 

Technical Paper 2005–01–1354. 
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The data used for the DRI analysis 

was similar to NHTSA’s 2003 Kahane 

study, using Fatality Analysis Reporting 

System (FARS) data for vehicle model 

years 1985 through 1998 for cars, and 

1985 through 1997 trucks. This data 

overlaps Kahane’s FARS data on model 

year 1991 to 1999 vehicles. However, 

DRI included 2-door passenger cars, 

whereas the Kahane study excluded all 

2-door vehicles. The 2003 Kahane study 

excluded 2-door passenger cars because 

it found that for MY 1991–1999 

vehicles, sports and muscle cars 

constituted a significant proportion of 

those vehicles. These vehicles have 

relatively high weight relative to their 

wheelbase, and are also 

disproportionately involved in crashes. 

Thus, Kahane concluded that including 

these vehicles in the analysis 

excessively skewed the regression 

results. However, as of July 1, 1999, 2-

door passenger cars represented 29% of 

the registered cars in the United States. 

DRI’s position was that this is a 

significant portion of the light duty 

fleet, too large to be ignored, and 

conclusions regarding the effects of 

weight and safety should be based on 

data for all cars, not just 4-doors. DRI 

did state in their conclusions that the 

results are sensitive to removing data for 

2-doors and wagons, and that the results 

for 4-door cars with respect to the 

effects of wheelbase and track width 

were no longer statistically significant 

when 2-door cars were removed. EPA 

and NHTSA recognize that it is 

important to properly account for 2-door 

cars in a regression analysis evaluating 

the impacts of vehicle weight on safety. 

Thus, the agencies seek comment on 

how to ensure that any analysis 

supporting the final rule accounts as 

fully as possible for the range of safety 

impacts due to weight reduction on the 

variety of vehicles regulated under these 

proposed standards. 

The DRI and Kahane studies also 

differ with respect to the impact of 

vehicle weight on rollover fatalities. The 

Kahane study treated curb weight as a 

surrogate for size and weight and 

analyzed them as a single variable. 

Using this method, the 2003 Kahane 

analysis indicates that curb weight 

reductions would increase fatalities due 

to rollovers. The DRI study differed by 

analyzing curb weight, wheelbase, and 

track as multiple variables and 

concluded that curb weight reduction 

would decrease rollover fatalities, and 

wheelbase and track reduction would 

increase rollover fatalities. DRI offers 

two potential root causes for higher curb 

weight resulting in higher rollover 

fatalities. The first is that a taller vehicle 

tends to be heavier than a shorter 

vehicle; therefore heavier vehicles may 

be more likely to rollover because the 

vehicle height and weight are correlated 

with vehicle center of gravity height. 

The second is that FMVSS 216 for roof 

crush strength requirements for 

passenger cars of model years 1995 

through 1999 were proportional to the 

unloaded vehicle weight if the weight is 

less than 3,333 lbs, however they were 

a constant if the weight is greater than 

3,333 lbs. Therefore heavier vehicles 

may have had relatively less rollover 

crashworthiness. 

NHTSA has rejected the DRI analysis, 

and has not relied on it for its 

evaluation of safety impact changes in 

CAFE standards. See Section IV.G.6 of 

this Notice, as well as NHTSA’s March 

2009 Final Rulemaking for MY2011 

CAFE standards (see 74 FR at 14402– 

05). 

The DRI and Kahane analyses of the 

FARS data appear similar in one respect 

because the results are reproducible 

between the two studies when using 

aggregated vehicle attributes for 4-door 

cars.230 231 232 However, when DRI and 

NHTSA separately analyzed individual 

vehicle attributes of mass, wheelbase 

and track width, DRI and NHTSA 

obtained different results for passenger 

cars. NHTSA has raised this as a 

concern with the DRI study. When 2-

door vehicles are removed from the data 

set EPA is concerned that the results 

may no longer be statistically significant 

with respect to independent vehicle 

attributes due to the small remaining 

data set, as DRI stated in the 2005 study. 

The DRI analysis concluded that there 

would be a small reduction in fatalities 

for cars and for trucks for a 100 pound 

reduction in curb weight without 

accompanied vehicle footprint or size 

changes. EPA notes that if DRI’s results 

were to be applied using the curb 

weight reductions predicted by the 

OMEGA model, an overall reduction in 

fatalities would be predicted. EPA 

invites comment on all aspects of the 

issue of the impact of this kind of 

weight reduction on safety, including 

the usefulness of the DRI study in 

evaluating this issue. 

The agencies are committed to 

continuing to analyze vehicle safety 

issues so a more informed evaluation 

230 ‘‘Supplemental Results on the Independent 

Effects of Curb Weight, Wheelbase and Track on 

Fatality Risk’’, Dynamic Research, Inc., DRI–TR– 

05–01, May 2005. 

231 ‘‘An Assessment of the Effects of Vehicle 

Weight and Size on Fatality Risk in 1985 to 1998 

Model Year Passenger Cars and 1985 to 1997 Model 

Year’’, M. Van Auken and J. Zellner, Dynamic 

Research Inc., Society of Automotive Engineers 

Technical Paper 2005–01–1354. 

232 FR Vol. 74, No. 59, beginning on pg. 14402. 

can be made. We request comment on 

this issue. These comments should 

include not only further discussion and 

analysis of the relevant studies but data 

and analysis which can allow the 

agencies to more accurately quantify 

any potential safety issues with the 

proposed standards. 

G. How Would the Proposal Impact 

Non-GHG Emissions and Their 

Associated Effects? 

In addition to reducing the emissions 

of greenhouse gases, this proposal 

would influence the emissions of 

‘‘criteria’’ air pollutants and air toxics 

(i.e., hazardous air pollutants). The 

criteria air pollutants include carbon 

monoxide (CO), fine particulate matter 

(PM2.5), sulfur dioxide (SOX) and the 

ozone precursors hydrocarbons (VOC) 

and oxides of nitrogen (NOX); the air 

toxics include benzene, 1,3-butadiene, 

formaldehyde, acetaldehyde, and 

acrolein. Our estimates of these nonGHG emission impacts from the 

proposed program are shown by 

pollutant in Table III.G–1 and Table 

III.G–2 in total, and broken down by the 

two drivers of these changes: (a) 

‘‘Upstream’’ emission reductions due to 

decreased extraction, production and 

distribution of motor gasoline; and (b) 

‘‘downstream’’ emission increases, 

reflecting the effects of VMT rebound 

(discussed in Sections III.F and III.H). 

Total program impacts on criteria and 

toxics emissions are discussed below, 

followed by individual discussions of 

the upstream and downstream impacts. 

Those are followed by discussions of the 

effects on air quality, health, and other 

environmental concerns. 

As discussed in Chapter 5 of the 

DRIA, the impacts presented here are 

only from petroleum (i.e., EPA assumes 

that total volumes of ethanol and other 

renewable fuels will remain unchanged 

due to this program). Ethanol use was 

modeled at the volumes projected in 

AEO2007 for the reference and control 

case; thus no changes are projected in 

upstream emissions related to ethanol 

production and distribution. However, 

due to the decreased gasoline volume 

associated with this proposal, a greater 

market share of E10 is expected relative 

to E0, which would be expected to have 

some effect on fleetwide average nonGHG emission rates. This effect, which 

is likely small relative to the other 

effects considered here, has not been 

accounted for in the downstream 

emission modeling conducted for this 

proposal, but EPA does plan to address 

it in the final rule air quality analysis, 

for which localized impacts could be 

more significant. A more comprehensive 

analysis of the impacts of different 
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49592 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

ethanol and gasoline volume scenarios 

is being prepared as part of EPA’s RFS2 

rulemaking package.233 

As shown in Table III.G–1, EPA 

estimates that this program would result 

in reductions of NOX, VOC, PM and 

SOX, but would increase CO emissions. 

For NOX, VOC, PM and SOX, we 

estimate net reductions in criteria 

pollutant emissions because the 

emissions reductions from upstream 

sources are larger than the emission 

increases due to additional driving (i.e., 

the ‘‘rebound effect’’). In the case of CO, 

we estimate slight emission increases, 

because there are relatively small 

reductions in upstream emissions, and 

thus the projected emission increases 

due to additional driving are greater 

than the projected emission decreases 

due to reduced fuel production. EPA 

estimates that the proposed program 

would result in small changes for toxic 

emissions compared to total U.S. 

inventories across all sectors. For all 

pollutants the overall impact of the 

program would be relatively small 

233 74 FR 24904. See also Docket EPA–HQ–OAR– 

2005–0161. 

compared to total U.S. inventories 

across all sectors. In 2030 EPA estimates 

the proposed program would reduce 

these total NOX, PM and SOX 

inventories by 0.2 to 0.3 percent and 

reduce the VOC inventory by 1.2 

percent, while increasing the total 

national CO inventory by 0.4 percent. 

As shown in Table III.G–2, EPA 

estimates that the proposed program 

would result in small changes for toxic 

emissions compared to total U.S. 

inventories across all sectors. In 2030 

EPA estimates the program would 

reduce total benzene and formaldehyde 

by 0.04 percent. Total acrolein, 

acetaldehyde, and 1,3-butadiene would 

increase by 0.03 to 0.2 percent. 

Other factors which may impact nonGHG emissions, but are not estimated in 

this analysis, include: 

• Vehicle technologies used to reduce 

tailpipe CO2 emissions; because the 

regulatory standards for non-GHG 

emissions are the primary driver for 

these emissions, EPA expects the impact 

of this program to be negligible on nonGHG emission rates per mile. 

• The potential for increased market 

penetration of diesel vehicles; because 

these vehicles would be held to the 

same certification and in-use standards 

for criteria pollutants as their gasoline 

counterparts, EPA expects their impact 

to be negligible on criteria pollutants 

and other non-GHG emissions. 

• Early introduction of electric 

vehicles and plug-in hybrid electric 

vehicles, which would reduce criteria 

emissions in cases where they are able 

to certify to lower certification 

standards. It would also likely reduce 

gaseous air toxics. 

• Reduced refueling emissions due to 

less frequent refueling events and 

reduced annual refueling volumes 

resulting from the GHG standards. 

• Increased hot soak evaporative 

emissions due to the likely increase in 

number of trips associated with VMT 

rebound modeled in this proposal. 

• Increased market share of E10 

relative to E0 due to the decreased 

overall gasoline consumption of this 

proposal combined with an unchanged 

fuel ethanol volume. 

EPA invites comments on the possible 

contribution of these factors to non-GHG 

emissions. 

BILLING CODE 4910–59–P 

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Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 49593 

BILLING CODE 4910–59–C 

1. Upstream Impacts of Program 

Reducing tailpipe CO2 emissions from 

light-duty cars and trucks through 

tailpipe standards and improved A/C 

efficiency will result in reduced fuel 

demand and reductions in the emissions 

associated with all of the processes 

involved in getting petroleum to the 

pump. These upstream emission 

impacts on criteria pollutants are 

summarized in Table III.G–1. The 

upstream reductions grow over time as 

the fleet turns over to cleaner CO2 

vehicles, so that by 2030 VOC would 

decrease by 148,000 tons, NOX by 

43,000 tons, and PM2.5 by 6,000 tons. 

Table III.G–2 shows the corresponding 

impacts on upstream air toxic emissions 

in 2030. Formaldehyde decreases by 112 

tons, benzene by 320 tons, acetaldehyde 

by 15 tons, acrolein by 2 tons, and 1,3-

butadiene by 3 tons. 

To determine these impacts, EPA 

estimated the impact of reduced 

petroleum volumes on the extraction 

and transportation of crude oil as well 

as the production and distribution of 

finished gasoline. For the purpose of 

assessing domestic-only emission 

reductions it was necessary to estimate 

the fraction of fuel savings attributable 

to domestic finished gasoline, and of 

this gasoline what fraction is produced 

from domestic crude. For this analysis 

EPA estimated that 50 percent of fuel 

savings is attributable to domestic 

finished gasoline and that 90 percent of 

this gasoline originated from imported 

crude. Emission factors for most 

upstream emission sources are based on 

the GREET1.8 model, developed by 

DOE’s Argonne National Laboratory,234 

but in some cases the GREET values 

were modified or updated by EPA to be 

consistent with the National Emission 

Inventory (NEI).235 The primary updates 

for this analysis were to incorporate 

newer information on gasoline 

distribution emissions for VOC from the 

NEI, which were significantly higher 

than GREET estimates; and the 

incorporation of upstream emission 

factors for the air toxics estimated in 

this analysis: benzene, 1,3-butadiene, 

acetaldehyde, acrolein, and 

234 Greenhouse Gas, Regulated Emissions, and 

Energy Use in Transportation model (GREET), U.S. 

Department of Energy, Argonne National 

Laboratory, http://www.transportation.anl.gov/ 

modeling_simulation/GREET/. 

235 EPA. 2002 National Emissions Inventory (NEI) 

Data and Documentation, http://www.epa.gov/ttn/ 

chief/net/2002inventory.html. 
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49594 Federal Register / Vol. 74, No. 186 / Monday, September 28, 2009 / Proposed Rules 

formaldehyde. The development of 

these emission factors is detailed in 

DRIA Chapter 5. 

2. Downstream Impacts of Program 

As discussed in more detail in Section 

III.H, the effect of fuel cost on VMT 

(‘‘rebound’’) was accounted for in our 

assessment of economic and 

environmental impacts of this proposed 

rule. A 10 percent rebound case was 

used for this analysis, meaning that 

VMT for affected model years is 

modeled as increasing by 10 percent as 

much as the increase in fuel economy; 

i.e., a 10 percent increase in fuel 

economy would yield a 1.0 percent 

increase in VMT. 

Downstream emission impacts of the 

rebound effect are summarized in Table 

III.G–1 for criteria pollutants and 

precursors and Table III.G–2 for air 

toxics. The emission increases from the 

rebound effect grow over time as the 

fleet turns over to cleaner CO2 vehicles, 

so that by 2030 VOC would increase by 

5,500 tons, NOX by 16,000 tons, and 

PM2.5 by 570 tons. Table III.G–2 shows 

the corresponding impacts on air toxic 

emissions. The most noteworthy of 

these impacts in 2030 are 40 additional 

tons of 1,3-butadiene, 75 tons of 

acetaldehyde, 240 tons of benzene, 96 

tons of formaldehyde, and 4 tons of 

acrolein. 

For this analysis the reference case 

non-GHG emissions for light duty 

vehicles and trucks were derived using 

EPA’s MOtor Vehicle Emission 

Simulator (MOVES) model for VOC, CO, 

NOX, PM and air toxics. PM2.5 emission 

estimates include additional 

adjustments for low temperatures, 

discussed in detail in the DRIA. Because 

this modeling was based on calendar 

year estimates, estimating the rebound 

effect required a fleet-weighted rebound 

factor to be calculated for calendar years 

2020 and 2030; these factors are 

presented in DRIA Chapter 5. 

As discussed in Section III.H, EPA 

will be taking comment on the 

appropriate level of rebound rate for this 

analysis. The sensitivity of the 

downstream emission increases shown 

in Tables III.G–1 and III.G–2 to the level 

of rebound would be in direct 

proportion to the rebound rate itself; 

since zero rebound would result in zero 

emission increase, the downstream 

results presented in Table III.G–1 and 

Table III.G–2 can be directly scaled to 

estimate the effect of lower rebound 

rates. 

3. Health Effects of Non-GHG Pollutants 

a. Particulate Matter 

i. Background 

Particulate matter is a generic term for 

a broad class of chemically and 

physically diverse substances. It can be 

principally characterized as discrete 

particles that exist in the condensed 

(liquid or solid) phase spanning several 

orders of magnitude in size. Since 1987, 

EPA has delineated that subset of 

inhalable particles small enough to 

penetrate to the thoracic region 

(including the tracheobronchial and 

alveolar regions) of the respiratory tract 

(referred to as thoracic particles). 

Current NAAQS use PM2.5 as the 

indicator for fine particles (with PM2.5 

referring to particles with a nominal 

mean aerodynamic diameter less than or 

equal to 2.5 μm), and use PM10 as the 

indicator for purposes of regulating the 

coarse fraction of PM10 (referred to as 

thoracic coarse particles or coarsefraction particles; generally including 

particles with a nominal mean 

aerodynamic diameter greater than 2.5 

μm and less than or equal to 10 μm, or 

PM10–2.5). Ultrafine particles are a subset 

of fine particles, generally less than 100 

nanometers (0.1 μm) in aerodynamic 

diameter. 

Fine particles are produced primarily 

by combustion processes and by 

transformations of gaseous emissions 

(e.g., SOX, NOX and VOC) in the 

atmosphere. The chemical and physical 

properties of PM2.5 may vary greatly 

with time, region, meteorology, and 

source category. Thus, PM2.5 may 

include a complex mixture of different 

pollutants including sulfates, nitrates, 

organic compounds, elemental carbon 

and metal compounds. These particles 

can remain in the atmosphere for days 

to weeks and travel hundreds to 

thousands of kilometers. 

ii. Health Effects of PM 

Scientific studies show ambient PM is 

associated with a series of adverse 

health effects. These health effects are 

discussed in detail in EPA’s 2004 

Particulate Matter Air Quality Criteria 

Document (PM AQCD) and the 2005 PM 

Staff Paper. 236 237 238 Further discussion 

236 U.S. EPA (2004). Air Quality Criteria for 

Particulate Matter. Volume I EPA600/P–99/002aF 

and Volume II EPA600/P–99/002bF. Retrieved on 

March 19, 2009 from Docket EPA–HQ–OAR–2003– 

0190 at http://www.regulations.gov/. 

237 U.S. EPA. (2005). Review of the National 

Ambient Air Quality Standard for Particulate 

Matter: Policy Assessment of Scientific and 

Technical Information, OAQPS Staff Paper. EPA– 

452/R–05–005a. Retrieved March 19, 2009 from 

http://www.epa.gov/ttn/naaqs/standards/pm/data/ 

pmstaffpaper_20051221.pdf. 

of health effects associated with PM can 

also be found in the DRIA for this rule. 

Health effects associated with shortterm exposures (hours to days) to 

ambient PM include premature 

mortality, aggravation of cardiovascular 

and lung disease (as indicated by 

increased hospital admissions and 

emergency department visits), increased 

respiratory symptoms including cough 

and difficulty breathing, decrements in 

lung function, altered heart rate rhythm, 

and other more subtle changes in blood 

markers related to cardiovascular 

health.239 Long-term exposure to PM2.5 

and sulfates has also been associated 

with mortality from cardiopulmonary 

disease and lung cancer, and effects on 

the respiratory system such as reduced 

lung function growth or development of 

respiratory disease. A new analysis 

shows an association between long-term 

PM2.5 exposure and a measure of 

atherosclerosis development.240 241 

Studies examining populations 

exposed over the long term (one or more 

years) to different levels of air pollution, 

including the Harvard Six Cities Study 

238 The PM NAAQS is currently under review and 

the EPA is considering all available science on PM 

health effects, including information which has 

been published since 2004, in the development of 

the upcoming PM Integrated Science Assessment 

Document (ISA). A second draft of the PM ISA was 

completed in July 2009 and was submitted for 

review by the Clean Air Scientific Advisory 

Committee (CASAC) of EPA’s Science Advisory 

Board. Comments from the general public have also 

been requested. For more information, see http:// 

cfpub.epa.gov/ncea/cfm/ 

recordisplay.cfm?deid=210586. 

239 U.S. EPA. (2006). National Ambient Air 

Quality Standards for Particulate Matter; Proposed 

Rule. 71 FR 2620, January 17, 2006. 

240 Ku ̈ nzli, N., Jerrett, M., Mack, W.J., et al. 

(2004). Ambient air pollution and atherosclerosis in 

Los Angeles. Environ Health Perspect., 113, 201– 

206. 

241 This study is included in the 2006 Provisional 

Assessment of Recent Studies on Health Effects of 

Particulate Matter Exposure. The provisional 

assessment did not and could not (given a very 

short timeframe) undergo the extensive critical 

review by CASAC and the public, as did the PM 

AQCD. The provisional assessment found that the 

‘‘new’’ studies expand the scientific information 

and provide important insights on the relationship 

between PM exposure and health effects of PM. The 

provisional assessment also found that ‘‘new’’ 

studies generally strengthen the evidence that acute 

and chronic exposure to fine particles and acute 

exposure to thoracic coarse particles are associated 

with health effects. Further, the provisional science 

assessment found that the results reported in the 

studies did not dramatically diverge from previous 

findings, and taken in context with the findings of 

the AQCD, the new information and findings did 

not materially change any of the broad scientific 

conclusions regarding the health effects of PM 

exposure made in the AQCD. However, it is 

important to note that this assessment was limited 

to screening, surveying, and preparing a provisional 

assessment of these studies. For reasons outlined in 

Section I.C of the preamble for the final PM NAAQS 

rulemaking in 2006 (see 71 FR 61148–49, October 

17, 2006), EPA based its NAAQS decision on the 

science presented in the 2004 AQCD. 
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and the American Cancer Society Study, 

show associations between long-term 

exposure to ambient PM2.5 and both 

total and cardiopulmonary premature 

mortality.242 243 244 In addition, an 

extension of the American Cancer 

Society Study shows an association 

between PM2.5 and sulfate 

concentrations and lung cancer 

mortality.245 

b. Ozone 

i. Background 

Ground-level ozone pollution is 

typically formed by the reaction of VOC 

and NOX in the lower atmosphere in the 

presence of heat and sunlight. These 

pollutants, often referred to as ozone 

precursors, are emitted by many types of 

pollution 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.246 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 hightemperature day. Ozone can be 

transported hundreds of miles 

downwind of precursor emissions, 

resulting in elevated ozone levels even 

242 Dockery, D.W., Pope, C.A. III, Xu, X, et al. 

(1993). An association between air pollution and 

mortality in six U.S. cities. N Engl J Med, 329, 

1753–1759. Retrieved on March 19, 2009 from 

http://content.nejm.org/cgi/content/full/329/24/ 

1753. 

243 Pope, C.A., III, Thun, M.J., Namboodiri, M.M., 

Dockery, D.W., Evans, J.S., Speizer, F.E., and Heath, 

C.W., Jr. (1995). Particulate air pollution as a 

predictor of mortality in a prospective study of U.S. 

adults. Am. J. Respir. Crit. Care Med, 151, 669–674. 

244 Krewski, D., Burnett, R.T., Goldberg, M.S., et 

al. (2000). Reanalysis of the Harvard Six Cities 

study and the American Cancer Society study of 

particulate air pollution and mortality. A special 

report of the Institute’s Particle Epidemiology 

Reanalysis Project. Cambridge, MA: Health Effects 

Institute. Retrieved on March 19, 2009 from 

http://es.epa.gov/ncer/science/pm/hei/ReanExecSumm.pdf. 

245 Pope, C.A., III, Burnett, R.T., Thun, M. J., 

Calle, E.E., Krewski, D., Ito, K., Thurston, G.D., 

(2002). Lung cancer, cardiopulmonary mortality, 

and long-term exposure to fine particulate air 

pollution. J. Am. Med. Assoc., 287, 1132–1141. 

246 U.S. EPA. (2006). Air Quality Criteria for 

Ozone and Related Photochemical Oxidants (Final). 

EPA/600/R–05/004aF-cF. Washington, DC: U.S. 

EPA. Retrieved on March 19, 2009 from Docket 

EPA–HQ–OAR–2003–0190 at http:// 

www.regulations.gov/. 

in areas with low local VOC or NOX 

emissions. 

ii. Health Effects of Ozone 

The health and welfare effects of 

ozone are well documented and are 

assessed in EPA’s 2006 Air Quality 

Criteria Document (ozone AQCD) and 

2007 Staff Paper.247 248 Ozone can 

irritate the respiratory system, causing 

coughing, throat irritation, and/or 

uncomfortable sensation in the chest. 

Ozone can reduce lung function and 

make it more difficult to breathe deeply; 

breathing may also become more rapid 

and shallow than normal, thereby 

limiting a person’s activity. Ozone can 

also aggravate asthma, leading to more 

asthma attacks that require medical 

attention and/or the use of additional 

medication. In addition, there is 

suggestive evidence of a contribution of 

ozone to cardiovascular-related 

morbidity and highly suggestive 

evidence that short-term ozone exposure 

directly or indirectly contributes to nonaccidental and cardiopulmonary-related 

mortality, but additional research is 

needed to clarify the underlying 

mechanisms causing these effects. In a 

recent report on the estimation of ozonerelated premature mortality published 

by the National Research Council (NRC), 

a panel of experts and reviewers 

concluded that short-term exposure to 

ambient ozone is likely to contribute to 

premature deaths and that ozone-related 

mortality should be included in 

estimates of the health benefits of 

reducing ozone exposure.249 Animal 

toxicological evidence indicates that 

with repeated exposure, ozone can 

inflame and damage the lining of the 

lungs, which may lead to permanent 

changes in lung tissue and irreversible 

reductions in lung function. People who 

are more susceptible to effects 

associated with exposure to ozone can 

include children, the elderly, and 

individuals with respiratory disease 

such as asthma. Those with greater 

exposures to ozone, for instance due to 

time spent outdoors (e.g., children and 

247 U.S. EPA. (2006). Air Quality Criteria for 

Ozone and Related Photochemical Oxidants (Final). 

EPA/600/R–05/004aF–cF. Washington, DC: U.S. 

EPA. Retrieved on March 19, 2009 from Docket 

EPA–HQ–OAR–2003–0190 at http:// 

www.regulations.gov/. 

248 U.S. EPA. (2007). Review of the National 

Ambient Air Quality Standards for Ozone: Policy 

Assessment of Scientific and Technical 

Information, OAQPS Staff Paper. EPA–452/R–07– 

003. Washington, DC. U.S. EPA. Retrieved on 

March 19, 2009 from Docket EPA–HQ–OAR–2003– 

0190 at http://www.regulations.gov/. 

249 National Research Council (NRC), 2008. 

Estimating Mortality Risk Reduction and Economic 

Benefits from Controlling Ozone Air Pollution. The 

National Academies Press: Washington, DC. 

outdoor workers), are of particular 

concern. 

The 2006 ozone AQCD also examined 

relevant new scientific information that 

has emerged in the past decade, 

including the impact of ozone exposure 

on such health effects as changes in 

lung structure and biochemistry, 

inflammation of the lungs, exacerbation 

and causation of asthma, respiratory 

illness-related school absence, hospital 

admissions and premature mortality. 

Animal toxicological studies have 

suggested potential interactions between 

ozone and PM with increased responses 

observed to mixtures of the two 

pollutants compared to either ozone or 

PM alone. The respiratory morbidity 

observed in animal studies along with 

the evidence from epidemiologic studies 

supports a causal relationship between 

acute ambient ozone exposures and 

increased respiratory-related emergency 

room visits and hospitalizations in the 

warm season. In addition, there is 

suggestive evidence of a contribution of 

ozone to cardiovascular-related 

morbidity and non-accidental and 

cardiopulmonary mortality. 

c. NOX and SOX 

i. Background 

Nitrogen dioxide (NO2) is a member of 

the NOX family of gases. Most NO2 is 

formed in the air through the oxidation 

of nitric oxide (NO) emitted when fuel 

is burned at a high temperature. SO2, a 

member of the sulfur oxide (SOX) 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. 

SO2 and NO2 can dissolve in water 

vapor and further oxidize to form 

sulfuric and nitric acid which react with 

ammonia to form sulfates and nitrates, 

both of which are important 

components of ambient PM. The health 

effects of ambient PM are discussed in 

Section III.G.3.a of this preamble. NOX 

along with non-methane hydrocarbon 

(NMHC) are the two major precursors of 

ozone. The health effects of ozone are 

covered in Section III.G.3.b. 

ii. Health Effects of NO2 

Information on the health effects of 

NO2 can be found in the U.S. 

Environmental Protection Agency 

Integrated Science Assessment (ISA) for 

Nitrogen Oxides.250 The U.S. EPA has 

concluded that the findings of 

epidemiologic, controlled human 

250 U.S. EPA (2008). Integrated Science 

Assessment for Oxides of Nitrogen—Health Criteria 

(Final Report). EPA/600/R–08/071. Washington, 

DC: U.S. EPA. Retrieved on March 19, 2009 from 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm? 

deid=194645. 
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exposure, and animal toxicological 

studies provide evidence that is 

sufficient to infer a likely causal 

relationship between respiratory effects 

and short-term NO2 exposure. The ISA 

concludes that the strongest evidence 

for such a relationship comes from 

epidemiologic studies of respiratory 

effects including symptoms, emergency 

department visits, and hospital 

admissions. The ISA also draws two 

broad conclusions regarding airway 

responsiveness following NO2 exposure. 

First, the ISA concludes that NO2 

exposure may enhance the sensitivity to 

allergen-induced decrements in lung 

function and increase the allergeninduced airway inflammatory response 

at exposures as low as 0.26 ppm NO2 for 

30 minutes. Second, exposure to NO2 

has been found to enhance the inherent 

responsiveness of the airway to 

subsequent nonspecific challenges in 

controlled human exposure studies of 

asthmatic subjects. Enhanced airway 

responsiveness could have important 

clinical implications for asthmatics 

since transient increases in airway 

responsiveness following NO2 exposure 

have the potential to increase symptoms 

and worsen asthma control. Together, 

the epidemiologic and experimental 

data sets form a plausible, consistent, 

and coherent description of a 

relationship between NO2 exposures 

and an array of adverse health effects 

that range from the onset of respiratory 

symptoms to hospital admission. 

Although the weight of evidence 

supporting a causal relationship is 

somewhat less certain than that 

associated with respiratory morbidity, 

NO2 has also been linked to other health 

endpoints. These include all-cause 

(nonaccidental) mortality, hospital 

admissions or emergency department 

visits for cardiovascular disease, and 

decrements in lung function growth 

associated with chronic exposure. 

iii. Health Effects of SO2 

Information on the health effects of 

SO2 can be found in the U.S. 

Environmental Protection Agency 

Integrated Science Assessment for 

Sulfur Oxides.251 SO2 has long been 

known to cause adverse respiratory 

health effects, particularly among 

individuals with asthma. Other 

potentially sensitive groups include 

children and the elderly. During periods 

of elevated ventilation, asthmatics may 

251 U.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. Retrieved on March 18, 2009 from http:// 

cfpub.epa.gov/ncea/cfm/recordisplay. 

cfm?deid=198843. 

experience symptomatic 

bronchoconstriction within minutes of 

exposure. Following an extensive 

evaluation of health evidence from 

epidemiologic and laboratory studies, 

the EPA has concluded that there is a 

causal relationship between respiratory 

health effects and short-term exposure 

to SO2. Separately, based on an 

evaluation of the epidemiologic 

evidence of associations between shortterm exposure to SO2 and mortality, the 

EPA has concluded that the overall 

evidence is suggestive of a causal 

relationship between short-term 

exposure to SO2 and mortality. 

d. Carbon Monoxide 

Carbon monoxide (CO) forms as a 

result of incomplete fuel combustion. 

CO enters the bloodstream through the 

lungs, forming carboxyhemoglobin and 

reducing the delivery of oxygen to the 

body’s organs and tissues. The health 

threat from CO is most serious for those 

who suffer from cardiovascular disease, 

particularly those with angina or 

peripheral vascular disease. Healthy 

individuals also are affected, but only at 

higher CO levels. Exposure to elevated 

CO levels is associated with impairment 

of visual perception, work capacity, 

manual dexterity, learning ability and 

performance of complex tasks. Carbon 

monoxide also contributes to ozone 

nonattainment since carbon monoxide 

reacts photochemically in the 

atmosphere to form ozone.252 

Additional information on CO related 

health effects can be found in the 

Carbon Monoxide Air Quality Criteria 

Document (CO AQCD).253 254 

e. Air Toxics 

Motor vehicle emissions contribute to 

ambient levels of air toxics known or 

suspected as human or animal 

carcinogens, or that have noncancer 

health effects. The population 

experiences an elevated risk of cancer 

and other noncancer health effects from 

252 U.S. EPA (2000). Air Quality Criteria for 

Carbon Monoxide, EPA/600/P–99/001F. This 

document is available in Docket EPA–HQ–OAR– 

2004–0008. 

253 U.S. EPA (2000). Air Quality Criteria for 

Carbon Monoxide, EPA/600/P–99/001F. This 

document is available in Docket EPA–HQ–OAR– 

2004–0008. 

254 The CO NAAQS is currently under review and 

the EPA is considering all available science on CO 

health effects, including information which has 

been published since 2000, in the development of 

the upcoming CO Integrated Science Assessment 

Document (ISA). A first draft of the CO ISA was 

completed in March 2009 and was submitted for 

review by the Clean Air Scientific Advisory 

Committee (CASAC) of EPA’s Science Advisory 

Board. For more information, see http:// 

cfpub.epa.gov/ncea/cfm/ 

recordisplay.cfm?deid=203935. 

exposure to air toxics. 255 These 

compounds include, but are not limited 

to, benzene, 1,3-butadiene, 

formaldehyde, acetaldehyde, acrolein, 

polycyclic organic matter (POM), and 

naphthalene. These compounds, except 

acetaldehyde, were identified as 

national or regional risk drivers in the 

2002 National-scale Air Toxics 

Assessment (NATA) and have 

significant inventory contributions from 

mobile sources.256 Emissions and 

ambient concentrations of compounds 

are discussed in the DRIA chapter on 

emission inventories and air quality 

(Chapters 5 and 7, respectively). 

i. Benzene 

The EPA’s 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.257 258 259 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. The 

International Agency for Research on 

Carcinogens (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.260 261 

A number of adverse noncancer 

health effects including blood disorders, 

such as preleukemia and aplastic 

anemia, have also been associated with 

255 U. S. EPA. 2002 National-Scale Air Toxics 

Assessment. http://www.epa.gov/ttn/atw/ 

nata12002/risksum.html. 

256 U.S. EPA. 2009. National-Scale Air Toxics 

Assessment for 2002. http://www.epa.gov/ttn/atw/ 

nata2002/. 

257 U.S. EPA. 2000. Integrated Risk Information 

System File for Benzene. This material is available 

electronically at http://www.epa.gov/iris/subst/ 

0276.htm. 

258 International Agency for Research on Cancer 

(IARC). 1982. Monographs on the evaluation of 

carcinogenic risk of chemicals to humans, Volume 

29. Some industrial chemicals and dyestuffs, World 

Health Organization, Lyon, France, p. 345–389. 

259 Irons, 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. 

260 International Agency for Research on Cancer 

(IARC). 1987. Monographs on the evaluation of 

carcinogenic risk of chemicals to humans, Volume 

29. Supplement 7, Some industrial chemicals and 

dyestuffs, World Health Organization, Lyon, France. 

261 U.S. Department of Health and Human 

Services National Toxicology Program 11th Report 

on Carcinogens available at http:// 

www.ntp.niehs.nih.gov/go/16183. 
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long-term exposure to benzene.262 263 

The most sensitive noncancer effect 

observed in humans, based on current 

data, is the depression of the absolute 

lymphocyte count in blood.264 265 In 

addition, recent work, including studies 

sponsored by the Health Effects Institute 

(HEI), provides evidence that 

biochemical responses are occurring at 

lower levels of benzene exposure than 

previously know 266 267 268 269 EPA’s IRIS 

program has not yet evaluated these 

new data. 

ii. 1,3-Butadiene 

EPA has characterized 1,3-butadiene 

as carcinogenic to humans by 

inhalation.270 271 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.272 273 There 

262 Aksoy, M. (1989). Hematotoxicity and 

carcinogenicity of benzene. Environ. Health 

Perspect. 82: 193–197. 263 Goldstein, B.D. (1988). Benzene toxicity. 

Occupational medicine. State of the Art Reviews. 3: 

541–554. 264 Rothman, N., G.L. Li, M. Dosemeci, W.E. 

Bechtold, G.E. Marti, Y.Z. Wang, M. Linet, L.Q. Xi, 

W. Lu, M.T. Smith, N. Titenko-Holland, L.P. Zhang, 

W. Blot, S.N. Yin, and R.B. Hayes (1996) 

Hematotoxicity among Chinese workers heavily 

exposed to benzene. Am. J. Ind. Med. 29: 236–246. 

265 U.S. EPA (2002) Toxicological Review of 

Benzene (Noncancer Effects). Environmental 

Protection Agency, Integrated Risk Information 

System (IRIS), Research and Development, National 

Center for Environmental Assessment, Washington 

DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0276.htm. 

266 Qu, 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. 

267 Qu, 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. Am. J. Industr. Med. 42: 275–285. 268 Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et 

al. (2004) Hematotoxically in Workers Exposed to 

Low Levels of Benzene. Science 306: 1774–1776. 269 Turtletaub, 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. 270 U.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://www.epa.gov/iris/supdocs/ 

buta-sup.pdf. 

271 U.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://www.epa.gov/iris/subst/0139.htm. 

272 International 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. 

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. 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.274 

iii. Formaldehyde 

Since 1987, EPA has classified 

formaldehyde as a probable human 

carcinogen based on evidence in 

humans and in rats, mice, hamsters, and 

monkeys.275 EPA is currently reviewing 

recently published epidemiological 

data. For instance, research conducted 

by the National Cancer Institute (NCI) 

found an increased risk of 

nasopharyngeal cancer and 

lymphohematopoietic malignancies 

such as leukemia among workers 

exposed to formaldehyde.276 277 In an 

analysis of the lymphohematopoietic 

cancer mortality from an extended 

follow-up of these workers, NCI 

confirmed an association between 

lymphohematopoietic cancer risk and 

peak exposures.278 A recent National 

Institute of Occupational Safety and 

273 U.S. Department of Health and Human 

Services (2005) National Toxicology Program 11th 

Report on Carcinogens available at: 

ntp.niehs.nih.gov/index.cfm?objectid=32BA9724-

F1F6-975E-7FCE50709CB4C932. 

274 Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. 

(1996) Subchronic toxicity of 4-vinylcyclohexene in 

rats and mice by inhalation. Fundam. Appl. 

Toxicol. 32:1–10. 

275 U.S. EPA (1987) Assessment of Health Risks 

to Garment Workers and Certain Home Residents 

from Exposure to Formaldehyde, Office of 

Pesticides and Toxic Substances, April 1987. 

276 Hauptmann, M.; Lubin, J. H.; Stewart, P. A.; 

Hayes, R. B.; Blair, A. 2003. Mortality from 

lymphohematopeotic malignancies among workers 

in formaldehyde industries. Journal of the National 

Cancer Institute 95: 1615–1623. 

277 Hauptmann, 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. 

278 Beane Freeman, L. E.; Blair, A.; Lubin, J. H.; 

Stewart, P. A.; Hayes, R. B.; Hoover, R. N.; 

Hauptmann, M. 2009. Mortality from 

lymphohematopoietic malignancies among workers 

in formaldehyde industries: The National Cancer 

Institute cohort. J. National Cancer Inst. 101: 751– 

761. 

Health (NIOSH) study of garment 

workers also found increased risk of 

death due to leukemia among workers 

exposed to formaldehyde.279 Extended 

follow-up of a cohort of British chemical 

workers did not find evidence of an 

increase in nasopharyngeal or 

lymphohematopoietic cancers, but a 

continuing statistically significant 

excess in lung cancers was reported.280 

Recently, the IARC re-classified 

formaldehyde as a human carcinogen 

(Group 1).281 

Formaldehyde exposure also causes a 

range of noncancer health effects, 

including irritation of the eyes (burning 

and watering of the eyes), nose and 

throat. Effects from repeated exposure in 

humans include respiratory tract 

irritation, chronic bronchitis and nasal 

epithelial lesions such as metaplasia 

and loss of cilia. Animal studies suggest 

that formaldehyde may also cause 

airway inflammation—including 

eosinophil infiltration into the airways. 

There are several studies that suggest 

that formaldehyde may increase the risk 

of asthma—particularly in the 

young.282 283 

iv. 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.284 Acetaldehyde is reasonably 

anticipated to be a human carcinogen by 

the U.S. DHHS in the 11th Report on 

Carcinogens and is classified as possibly 

carcinogenic to humans (Group 2B) by 

279 Pinkerton, L. E. 2004. Mortality among a 

cohort of garment workers exposed to 

formaldehyde: an update. Occup. Environ. Med. 61: 

193–200. 

280 Coggon, D, EC Harris, J Poole, KT Palmer. 

2003. Extended follow-up of a cohort of British 

chemical workers exposed to formaldehyde. J 

National Cancer Inst. 95:1608–1615. 

281 International Agency for Research on Cancer 

(IARC). 2006. Formaldehyde, 2–Butoxyethanol and 

1-tert-Butoxypropan-2-ol. Volume 88. (in 

preparation), World Health Organization, Lyon, 

France. 

282 Agency for Toxic Substances and Disease 

Registry (ATSDR). 1999. Toxicological profile for 

Formaldehyde. Atlanta, GA: U.S. Department of 

Health and Human Services, Public Health Service. 

http://www.atsdr.cdc.gov/toxprofiles/tp111.html. 

283 WHO (2002) Concise International Chemical 

Assessment Document 40: Formaldehyde. 

Published under the joint sponsorship of the United 

Nations Environment Programme, the International 

Labour Organization, and the World Health 

Organization, and produced within the framework 

of the Inter-Organization Programme for the Sound 

Management of Chemicals. Geneva. 

284 U.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://www.epa.gov/iris/ 

subst/0290.htm. 
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the IARC.285 286 EPA is currently 

conducting a reassessment of cancer risk 

from inhalation exposure to 

acetaldehyde. The primary noncancer 

effects of exposure to acetaldehyde 

vapors include irritation of the eyes, 

skin, and respiratory tract.287 In shortterm (4 week) rat studies, degeneration 

of olfactory epithelium was observed at 

various concentration levels of 

acetaldehyde exposure.288 289 Data from 

these studies were used by EPA to 

develop an inhalation reference 

concentration. Some asthmatics have 

been shown to be a sensitive 

subpopulation to decrements in 

functional expiratory volume (FEV1 

test) and bronchoconstriction upon 

acetaldehyde inhalation.290 The agency 

is currently conducting a reassessment 

of the health hazards from inhalation 

exposure to acetaldehyde. 

v. Acrolein 

Acrolein is extremely acrid and 

irritating to humans when inhaled, with 

acute exposure resulting in upper 

respiratory tract irritation, mucus 

hypersecretion and congestion. Levels 

considerably lower than 1 ppm (2.3 mg/ 

m3) elicit subjective complaints of eye 

and nasal irritation and a decrease in 

the respiratory rate.291 292 Lesions to the 

lungs and upper respiratory tract of rats, 

rabbits, and hamsters have been 

observed after subchronic exposure to 

acrolein. Based on animal data, 

individuals with compromised 

respiratory function (e.g., emphysema, 

285 U.S. Department of Health and Human 

Services National Toxicology Program 11th Report 

on Carcinogens available at: ntp.niehs.nih.gov/ 

index.cfm?objectid=32BA9724-F1F6-975E7FCE50709CB4C932. 

286 International 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. 

287 U.S. EPA. 1991. Integrated Risk Information 

System File of Acetaldehyde. This material is 

available electronically at http://www.epa.gov/iris/ 

subst/0290.htm. 

288 Appleman, L. M., R. A. Woutersen, V. J. Feron, 

R. N. Hooftman, and W. R. F. Notten. 1986. Effects 

of the variable versus fixed exposure levels on the 

toxicity of acetaldehyde in rats. J. Appl. Toxicol. 6: 

331–336. 

289 Appleman, L.M., R.A. Woutersen, and V.J. 

Feron. 1982. Inhalation toxicity of acetaldehyde in 

rats. I. Acute and subacute studies. Toxicology. 23: 

293–297. 

290 Myou, S.; Fujimura, M.; Nishi K.; Ohka, T.; 

and Matsuda, T. 1993. Aerosolized acetaldehyde 

induces histamine-mediated bronchoconstriction in 

asthmatics. Am. Rev. Respir. Dis.148(4 Pt 1): 940– 

3. 

291 Weber-Tschopp, A; Fischer, T; Gierer, R; et al. 

(1977) Experimentelle reizwirkungen von Acrolein 

auf den Menschen. Int Arch Occup Environ Hlth 

40(2):117–130. In German 

292 Sim, VM; Pattle, RE. (1957) Effect of possible 

smog irritants on human subjects. J Am Med Assoc 

165(15):1908–1913. 

asthma) are expected to be at increased 

risk of developing adverse responses to 

strong respiratory irritants such as 

acrolein. This was demonstrated in mice 

with allergic airway-disease by 

comparison to non-diseased mice in a 

study of the acute respiratory irritant 

effects of acrolein.293 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.294 

EPA determined in 2003 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.295 The IARC 

determined in 1995 that acrolein was 

not classifiable as to its carcinogenicity 

in humans.296 

vi. Polycyclic Organic Matter (POM) 

POM is generally defined as a large 

class of organic compounds which have 

multiple benzene rings and a boiling 

point greater than 100 degrees Celsius. 

Many of the compounds included in the 

class of compounds known as POM are 

classified by EPA as probable human 

carcinogens based on animal data. One 

of these compounds, naphthalene, is 

discussed separately below. Polycyclic 

aromatic hydrocarbons (PAHs) are a 

subset of POM that contain only 

hydrogen and carbon atoms. A number 

of PAHs are known or suspected 

carcinogens. Recent studies have found 

that maternal exposures to PAHs (a 

subclass of POM) 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 at age 

293 Morris JB, Symanowicz PT, Olsen JE, et al. 

2003. Immediate sensory nerve-mediated 

respiratory responses to irritants in healthy and 

allergic airway-diseased mice. J Appl Physiol 

94(4):1563–1571. 

294 Sim VM, Pattle RE. Effect of possible smog 

irritants on human subjects JAMA165: 1980–2010, 

1957. 

295 U.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://www.epa.gov/iris/subst/ 

0364.htm. 

296 International 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. 

three.297 298 EPA has not yet evaluated 

these recent studies. 

vii. 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. EPA released an 

external review draft of a reassessment 

of the inhalation carcinogenicity of 

naphthalene based on a number of 

recent animal carcinogenicity 

studies.299 The draft reassessment 

completed external peer review.300 

Based on external peer review 

comments received, additional analyses 

are being undertaken. This external 

review draft does not represent official 

agency opinion and was released solely 

for the purposes of external peer review 

and public comment. Once EPA 

evaluates public and peer reviewer 

comments, the document will be 

revised. 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.301 

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.302 Naphthalene 

also causes a number of chronic noncancer effects in animals, including 

297 Perera, F.P.; Rauh, V.; Tsai, W–Y.; et al. (2002) 

Effect of transplacental exposure to environmental 

pollutants on birth outcomes in a multiethnic 

population. Environ Health Perspect. 111: 201–205. 

298 Perera, 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. Environ 

Health Perspect 114: 1287–1292. 

299 U. S. EPA. 2004. 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 http://www.epa.gov/iris/ 

subst/0436.htm. 

300 Oak 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. 

301 National Toxicology Program (NTP). (2004). 

11th Report on Carcinogens. Public Health Service, 

U.S. Department of Health and Human Services, 

Research Triangle Park, NC. Available from: 

http://ntp-server.niehs.nih.gov. 

302 International Agency for Research on Cancer 

(IARC). (2002). Monographs on the Evaluation of 

the Carcinogenic Risk of Chemicals for Humans. 

Vol. 82. Lyon, France. 
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abnormal cell changes and growth in 

respiratory and nasal tissues.303 

viii. Other Air Toxics 

In addition to the compounds 

described above, other compounds in 

gaseous hydrocarbon and PM emissions 

from vehicles will be affected by this 

proposed action. Mobile source air toxic 

compounds that would potentially be 

impacted include ethylbenzene, 

polycyclic organic matter, 

propionaldehyde, toluene, and xylene. 

Information regarding the health effects 

of these compounds can be found in 

EPA’s IRIS database.304 

4. Environmental Effects of Non-GHG 

Pollutants 

a. Visibility 

Visibility can be defined as the degree 

to which the atmosphere is transparent 

to visible light. Airborne particles 

degrade visibility by scattering and 

absorbing light. 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 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 

2004 PM AQCD as well as the 2005 PM 

Staff Paper.305 306 

EPA is pursuing a two-part strategy to 

address visibility. First, to address the 

welfare effects of PM on visibility, EPA 

has set secondary PM2.5 standards 

which act in conjunction with the 

establishment of a regional haze 

program. In setting this secondary 

standard, EPA has concluded that PM2.5 

causes adverse effects on visibility in 

303 U. S. EPA. 1998. Toxicological Review of 

Naphthalene, Environmental Protection Agency, 

Integrated Risk Information System, Research and 

Development, National Center for Environmental 

Assessment, Washington, DC. This material is 

available electronically at http://www.epa.gov/iris/ 

subst/0436.htm. 

304 U.S. EPA Integrated Risk Information System 

(IRIS) database is available at: www.epa.gov/iris. 

305 U.S. EPA. (2004). Air Quality Criteria for 

Particulate Matter (AQCD). Volume I Document No. 

EPA600/P–99/002aF and Volume II Document No. 

EPA600/P–99/002bF. Washington, DC: U.S. 

Environmental Protection Agency. Retrieved on 

March 18, 2009 from http://cfpub.epa.gov/ncea/ 

cfm/recordisplay.cfm?deid=87903. 

306 U.S. EPA. (2005). Review of the National 

Ambient Air Quality Standard for Particulate 

Matter: Policy Assessment of Scientific and 

Technical Information, OAQPS Staff Paper. EPA– 

452/R–05–005. Washington, DC: U.S. 

Environmental Protection Agency. 

various locations, depending on PM 

concentrations and factors such as 

chemical composition and average 

relative humidity. Second, section 169 

of the Clean Air Act provides additional 

authority to address existing visibility 

impairment and prevent future visibility 

impairment in the 156 national parks, 

forests and wilderness areas categorized 

as mandatory class I Federal areas (62 

FR 38680–81, July 18, 1997).307 In July 

1999, the regional haze rule (64 FR 

35714) was put in place to protect the 

visibility in mandatory class I Federal 

areas. Visibility can be said to be 

impaired in both PM2.5 nonattainment 

areas and mandatory class I Federal 

areas. 

b. Plant and Ecosystem Effects of Ozone 

Elevated ozone levels contribute to 

environmental effects, with impacts to 

plants and ecosystems being of most 

concern. Ozone can produce both acute 

and chronic injury in sensitive species 

depending on the concentration level 

and the duration of the exposure. Ozone 

effects also tend to accumulate over the 

growing season of the plant, so that even 

low concentrations experienced for a 

longer duration have the potential to 

create chronic stress on vegetation. 

Ozone damage to plants includes visible 

injury to leaves and impaired 

photosynthesis, both of which can lead 

to reduced plant growth and 

reproduction, resulting in reduced crop 

yields, forestry production, and use of 

sensitive ornamentals in landscaping. In 

addition, the impairment of 

photosynthesis, the process by which 

the plant makes carbohydrates (its 

source of energy and food), can lead to 

a subsequent reduction in root growth 

and carbohydrate storage below ground, 

resulting in other, more subtle plant and 

ecosystems impacts. 

These 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 forest and other 

natural vegetation can potentially lead 

to species shifts and loss from the 

affected ecosystems, resulting in a loss 

or reduction in associated ecosystem 

goods and services. Lastly, 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. The final 2006 ozone 

AQCD presents more detailed 

307 These areas are defined in section 162 of the 

Act 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. 

information on ozone effects on 

vegetation and ecosystems. 

c. Atmospheric Deposition 

Wet and dry deposition of ambient 

particulate matter delivers a complex 

mixture of metals (e.g., mercury, zinc, 

lead, nickel, aluminum, cadmium), 

organic compounds (e.g., POM, dioxins, 

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. 

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.308 

Adverse impacts on water quality can 

occur when atmospheric contaminants 

deposit to the water surface or when 

material deposited on the land enters a 

water body through runoff. Potential 

impacts of atmospheric deposition to 

water bodies include those related to 

both nutrient and toxic inputs. Adverse 

effects to human health and welfare can 

occur from the addition of excess 

nitrogen via atmospheric deposition. 

The nitrogen-nutrient enrichment 

contributes to toxic algae blooms and 

zones of depleted oxygen, which can 

lead to fish kills, frequently in coastal 

waters. Deposition of heavy metals or 

other toxins may lead to the human 

ingestion of contaminated fish, human 

ingestion of contaminated water, 

damage to the marine ecology, and 

limits to recreational uses. Several 

studies have been conducted in U.S. 

coastal waters and in the Great Lakes 

Region in which the role of ambient PM 

deposition and runoff is 

investigated.309 310 311 312 313 

308 U.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. This document is available in 

Docket EPA–HQ–OAR–2003–0190. 

309 U.S. EPA (2004) National Coastal Condition 

Report II. Office of Research and Development/ 

Office of Water. EPA–620/R–03/002. This document 

is available in Docket EPA–HQ–OAR–2003–0190. 

310 Gao, Y., E.D. Nelson, M.P. Field, et al. 2002. 

Characterization of atmospheric trace elements on 

PM2.5 particulate matter over the New York-New 

Jersey harbor estuary. Atmos. Environ. 36: 1077– 

1086. 

311 Kim, G., N. Hussain, J.R. Scudlark, and T.M. 

Church. 2000. Factors influencing the atmospheric 

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Atmospheric deposition of nitrogen 

and sulfur contributes to acidification, 

altering biogeochemistry and affecting 

animal and plant life in terrestrial and 

aquatic ecosystems across the U.S. 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 

nutritional value of preferred prey 

species, threatening biodiversity 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 include a decline in 

sensitive forest tree species, such as red 

spruce (Picea rubens) and sugar maple 

(Acer saccharum), and a loss of 

biodiversity of fishes, zooplankton, and 

macro invertebrates. 

In addition to the role nitrogen 

deposition plays in acidification, 

nitrogen deposition also causes 

ecosystem nutrient enrichment leading 

to eutrophication that alters 

biogeochemical cycles. Excess nitrogen 

also leads to the loss of nitrogen 

sensitive lichen species as they are 

outcompeted by invasive grasses as well 

as altering the biodiversity of terrestrial 

ecosystems, such as grasslands and 

meadows. For a broader explanation of 

the topics treated here, refer to the 

description in Chapter 7 of the DRIA. 

Adverse impacts on soil chemistry 

and plant life have been observed for 

areas heavily influenced by atmospheric 

deposition of nutrients, metals and acid 

species, resulting in species shifts, loss 

of biodiversity, forest decline and 

damage to forest productivity. Potential 

impacts also include adverse effects to 

human health through ingestion of 

contaminated vegetation or livestock (as 

in the case for dioxin deposition), 

reduction in crop yield, and limited use 

of land due to contamination. 

Atmospheric deposition of pollutants 

can reduce the aesthetic appeal of 

buildings and culturally important 

depositional fluxes of stable Pb, 210Pb, and 7Be 

into Chesapeake Bay. J. Atmos. Chem. 36: 65–79. 

312 Lu, R., R.P. Turco, K. Stolzenbach, et al. 2003. 

Dry deposition of airborne trace metals on the Los 

Angeles Basin and adjacent coastal waters. J. 

Geophys. Res. 108(D2, 4074): AAC 11–1 to 11–24. 

313 Marvin, C.H., M.N. Charlton, E.J. Reiner, et al. 

2002. Surficial sediment contamination in Lakes 

Erie and Ontario: A comparative analysis. J. Great 

Lakes Res. 28(3): 437–450. 

articles through soiling, and can 

contribute directly (or in conjunction 

with other pollutants) to structural 

damage by means of corrosion or 

erosion. Atmospheric deposition may 

affect materials principally by 

promoting and accelerating the 

corrosion of metals, by degrading paints, 

and by deteriorating building materials 

such as concrete and limestone. 

Particles contribute to these effects 

because of their electrolytic, 

hygroscopic, and acidic properties, and 

their ability to adsorb corrosive gases 

(principally sulfur dioxide). The rate of 

metal corrosion depends on a number of 

factors, including the deposition rate 

and nature of the pollutant; the 

influence of the metal protective 

corrosion film; the amount of moisture 

present; variability in the 

electrochemical reactions; the presence 

and concentration of other surface 

electrolytes; and the orientation of the 

metal surface. 

d. Environmental Effects of Air Toxics 

Fuel combustion emissions contribute 

to ambient levels of pollutants that 

contribute to adverse effects on 

vegetation. Volatile organic compounds 

(VOCs), some of which are considered 

air toxics, have long been suspected to 

play a role in vegetation damage.314 In 

laboratory experiments, a wide range of 

tolerance to VOCs has been observed.315 

Decreases 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.316 

Research suggests an adverse impact 

of vehicle exhaust on plants, which has 

in some cases been attributed to 

aromatic compounds and in other cases 

314 U.S. EPA. 1991. Effects of organic chemicals 

in the atmosphere on terrestrial plants. EPA/600/3– 

91/001. 

315 Cape JN, ID Leith, J Binnie, J Content, M 

Donkin, M Skewes, DN Price AR Brown, AD 

Sharpe. 2003. Effects of VOCs on herbaceous plants 

in an open-top chamber experiment. Environ. 

Pollut. 124:341–343. 

316 Cape JN, ID Leith, J Binnie, J Content, M 

Donkin, M Skewes, DN Price AR Brown, AD 

Sharpe. 2003. Effects of VOCs on herbaceous plants 

in an open-top chamber experiment. Environ. 

Pollut. 124:341–343. 

to nitrogen oxides.317 318 319 The impacts 

of VOCs on plant reproduction may 

have long-term implications for 

biodiversity and survival of native 

species near major roadways. Most of 

the studies of the impacts of VOCs on 

vegetation have focused on short-term 

exposure and few studies have focused 

on long-term effects of VOCs on 

vegetation and the potential for 

metabolites of these compounds to 

affect herbivores or insects. 

5. Air Quality Impacts of Non-GHG 

Pollutants 

a. Current Levels of PM2.5, Ozone, CO 

and Air Toxics 

This proposal may have impacts on 

levels of PM2.5, ozone, CO and air toxics. 

Nationally, levels of PM2.5, ozone, CO 

and air toxics are declining.320 321 

However, in 2005 EPA designated 39 

nonattainment areas for the 1997 PM2.5 

National Ambient Air Quality Standard 

(NAAQS) (70 FR 943, January 5, 2005). 

These areas are composed of 208 full or 

partial counties with a total population 

exceeding 88 million. The 1997 PM2.5 

NAAQS was recently revised and the 

2006 24-hour PM2.5 NAAQS became 

effective on December 18, 2006. The 

numbers above likely underestimate the 

number of counties that are not meeting 

the PM2.5 NAAQS because the 

nonattainment areas associated with the 

more stringent 2006 24-hour PM2.5 

NAAQS have not yet been designated. 

Area designations for the 2006 24-hour 

PM2.5 NAAQS are expected to be 

promulgated in 2009 and become 

effective 90 days after publication in the 

Federal Register. 

In addition, the U.S. EPA has recently 

amended the ozone NAAQS (73 FR 

16436, March 27, 2008). That final 2008 

ozone NAAQS rule set forth revisions to 

the previous 1997 NAAQS for ozone to 

provide increased protection of public 

health and welfare. As of June 5, 2009, 

there are 55 areas designated as 

317 Viskari E-L. 2000. Epicuticular wax of Norway 

spruce needles as indicator of traffic pollutant 

deposition. Water, Air, and Soil Pollut. 121:327– 

337. 

318 Ugrekhelidze D, F Korte, G Kvesitadze. 1997. 

Uptake and transformation of benzene and toluene 

by plant leaves. Ecotox. Environ. Safety 37:24–29. 

319 Kammerbauer H, H Selinger, R Rommelt, A 

Ziegler-Jons, D Knoppik, B Hock. 1987. Toxic 

components of motor vehicle emissions for the 

spruce Pciea abies. Environ. Pollut. 48:235–243. 

320 U.S. EPA (2008) National Air Quality Status 

and Trends through 2007. Office of Air Quality 

Planning and Standards, Research Triangle Park, 

NC. Publication No. EPA 454/R–08–006. http:// 

epa.gov/airtrends/2008/index.html. 

321 U.S. EPA (2007) Final Regulatory Impact 

Analysis: Control of Hazardous Air Pollutants from 

Mobile Sources, Office of Transportation and Air 

Quality, Ann Arbor, MI, Publication No. EPA420– 

R–07–002. http://www.epa.gov/otaq/toxics.htm. 
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nonattainment for the 1997 8-hour 

ozone NAAQS, comprising 290 full or 

partial counties with a total population 

of approximately 132 million people. 

These numbers do not include the 

people living in areas where there is a 

future risk of failing to maintain or 

attain the 1997 8-hour ozone NAAQS. 

The numbers above likely 

underestimate the number of counties 

that are not meeting the ozone NAAQS 

because the nonattainment areas 

associated with the more stringent 2008 

8-hour ozone NAAQS have not yet been 

designated. 

The proposed vehicle standards may 

also impact levels of ambient CO, a 

criteria pollutant (see Table III.G–1 

above for co-pollutant emission 

impacts). As of June 5, 2009 there are 

approximately 479,000 people living in 

a portion of Clark Co., NV which is 

currently the only area in the country 

that is designated as nonattainment for 

CO.322 

Further, 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.323 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 U.S. EPA’s recent mobile 

source air toxics rule.324 

b. Impacts of Proposed Standards on 

Future Ambient PM2.5, Ozone, CO and 

Air Toxics 

Full-scale photochemical air quality 

modeling is necessary to accurately 

project levels of PM2.5, ozone, CO and 

air toxics. For the final rule, a nationalscale air quality modeling analysis will 

be performed to analyze the impacts of 

the vehicle standards on PM2.5, 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 III.G.1 of the preamble 

presents projections of the changes in 

criteria pollutant and air toxics 

emissions due to the proposed vehicle 

322 Carbon Monoxide Nonattainment Area 

Summary: http://www.epa.gov/air/oaqps/greenbk/ 

cnsum.html. 

323 U.S. Environmental Protection Agency (2007). 

Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007. 

324 U.S. Environmental Protection Agency (2007). 

Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007. 

standards; the basis for those estimates 

is set out in Chapter 5 of the DRIA. The 

atmospheric chemistry related to 

ambient concentrations of PM2.5, ozone 

and air toxics is very complex, and 

making predictions based solely on 

emissions changes is extremely difficult. 

However, based on the magnitude of the 

emissions changes predicted to result 

from the proposed vehicle standards, 

EPA expects that there will be an 

improvement in ambient air quality, 

pending a more comprehensive analysis 

for the final rule. 

For the final rule, EPA intends to use 

a 2005-based Community Multi-scale 

Air Quality (CMAQ) modeling platform 

as the tool for the air quality modeling. 

The CMAQ modeling system is a 

comprehensive three-dimensional gridbased Eulerian air quality model 

designed to estimate the formation and 

fate of oxidant precursors, primary and 

secondary PM concentrations and 

deposition, and air toxics, over regional 

and urban spatial scales (e.g. over the 

contiguous U.S.).325 326 327 The CMAQ 

model is a well-known and wellestablished tool and is commonly used 

by EPA for regulatory analyses, for 

instance the recent ozone NAAQS 

proposal, and by States in developing 

attainment demonstrations for their 

State Implementation Plans.328 The 

CMAQ model (version 4.6) was peerreviewed in February of 2007 for EPA as 

reported in ‘‘Third Peer Review of 

CMAQ Model,’’ and the EPA Office of 

Research and Development (ORD) peer 

review report which includes version 

4.7 is currently being finalized.329 

CMAQ includes many science 

modules that simulate the emission, 

production, decay, deposition and 

transport of organic and inorganic gasphase and particle-phase pollutants in 

the atmosphere. EPA intends to use the 

most recent CMAQ version (version 

325 U.S. Environmental Protection Agency, Byun, 

D.W., and Ching, J.K.S., Eds, 1999. Science 

algorithms of EPA Models-3 Community Multiscale 

Air Quality (CMAQ modeling system, EPA/600/R– 

99/030, Office of Research and Development). 

326 Byun, D.W., and Schere, K.L., 2006. Review of 

the Governing Equations, Computational 

Algorithms, and Other Components of the Models3 Community Multiscale Air Quality (CMAQ) 

Modeling System, J. Applied Mechanics Reviews, 

59 (2), 51–77. 

327 Dennis, R.L., Byun, D.W., Novak, J.H., 

Galluppi, K.J., Coats, C.J., and Vouk, M.A., 1996. 

The next generation of integrated air quality 

modeling: EPA’s Models-3, Atmospheric 

Environment, 30, 1925–1938. 

328 U.S. EPA (2007). Regulatory Impact Analysis 

of the Proposed Revisions to the National Ambient 

Air Quality Standards for Ground-Level Ozone. 

EPA document number 442/R–07–008, July 2007. 

329 Aiyyer, A., Cohan, D., Russell, A., Stockwell, 

W., Tanrikulu, S., Vizuete, W., Wilczak, J., 2007. 

Final Report: Third Peer Review of the CMAQ 

Model. p. 23. 

4.7), which was officially released by 

EPA’s Office of Research and 

Development (ORD) in December 2008 

and reflects updates to earlier versions 

in a number of areas to improve the 

underlying science. These include (1) 

enhanced secondary organic aerosol 

(SOA) mechanism to include chemistry 

of isoprene, sesquiterpene, and aged incloud biogenic SOA in addition to 

terpene; (2) improved vertical 

convective mixing; (3) improved 

heterogeneous reaction involving nitrate 

formation; and (4) an updated gas-phase 

chemistry mechanism, Carbon Bond 05 

(CB05), with extensions to model 

explicit concentrations of air toxic 

species as well as chlorine and mercury. 

This mechanism, CB05-toxics, also 

computes concentrations of species that 

are involved in aqueous chemistry and 

that are precursors to aerosols. 

H. What Are the Estimated Cost, 

Economic, and Other Impacts of the 

Proposal? 

In this section, EPA presents the costs 

and impacts of EPA’s proposed GHG 

program. It is important to note that 

NHTSA’s CAFE standards and EPA’s 

GHG standards will both be in effect, 

and each will lead to increases in 

average fuel economy and CO2 

emissions reductions. The two agencies’ 

standards comprise the National 

Program, and this discussion of costs 

and benefits of EPA’s GHG standard 

does not change the fact that both the 

CAFE and GHG standards, jointly, are 

the source of the benefits and costs of 

the National Program. 

This section outlines the basis for 

assessing the benefits and costs of these 

standards and provides estimates of 

these costs and benefits. Some of these 

effects are private, meaning that they 

affect consumers and producers directly 

in their sales, purchases, and use of 

vehicles. These private effects include 

the costs of the technology, fuel savings, 

and the benefits of additional driving 

and reduced refueling. Other costs and 

benefits affect people outside the 

markets for vehicles and their use; these 

effects are termed external costs, 

because they affect people external to 

the market. The external effects include 

the climate impacts, the effects on nonGHG pollutants, and the effects on 

traffic, accidents, and noise due to 

additional driving. The sum of the 

private and external benefits and costs 

is the net social benefits of the program. 

There is some debate about the role of 

private benefits in assessing the benefits 

and costs of the program: If consumers 

have full information and perfect 

foresight in their vehicle purchase 

decisions, it is possible that they have 
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already considered these benefits in 

their vehicle purchase decisions. If so, 

then the inclusion of private benefits in 

the net benefits calculation may be 

inappropriate. If these conditions do not 

hold, then the private benefits may be 

a part of the net benefits. Section III.H.1 

discusses this issue more fully. 

EPA’s proposed program costs consist 

of the vehicle program costs (costs of 

complying with the vehicle CO2 

standards, taking into account FFV 

credits through 2015, the temporary 

lead-time alternative allowance 

standard program (TLAASP), full car/ 

truck trading, and the A/C credit 

program), along with the fuel savings 

associated with reduced fuel usage 

resulting from the proposed program. 

These proposed program costs also 

include external costs associated with 

noise, congestion, accidents, time spent 

refueling vehicles, and energy security 

impacts. EPA also presents the costeffectiveness of the proposed standards 

and our analysis of the expected 

economy-wide impacts. The projected 

monetized benefits of reducing GHG 

emissions and co-pollutant health and 

environmental impacts are also 

presented. EPA also presents our 

estimates of the impact on vehicle miles 

traveled and the impacts associated 

with those miles as well as other 

societal impacts of the proposed 

program, including energy security 

impacts. 

The total monetized benefits 

(excluding fuel savings) under the 

proposed program are projected to be 

$21 to $54 billion in 2030, assuming a 

3 percent discount rate and depending 

on the value used for the social cost of 

carbon. The costs of the proposed 

program in 2030 are estimated to be 

approximately $18 billion for new 

vehicle technology less $90 billion in 

savings realized by consumers through 

fewer fuel expenditures (calculated 

using pre-tax fuel prices). 

EPA has undertaken an analysis of the 

economy-wide impacts of the proposed 

GHG tailpipe standards as an 

exploratory exercise that EPA believes 

could provide additional insights into 

the potential impacts of the proposal.330 

These results were not a factor regarding 

the appropriateness of the proposed 

GHG tailpipe standards. It is important 

to note that the results of this modeling 

exercise are dependent on the 

assumptions associated with how 

consumers will respond to increases in 

higher vehicle costs and improved 

330 See Memorandum to Docket, ‘‘Economy-Wide 

Impacts of Proposed Greenhouse Gas Tailpipe 

Standards,’’ September 14, 2009 (Docket EPA–HQ– 

OAR–2009–0472). 

vehicle fuel economy as a result of the 

proposal. Section III.H.1 discusses the 

underlying distinctions and 

implications of the role of consumer 

response in economic impacts. 

Further information on these and 

other aspects of the economic impacts of 

our proposed rule are summarized in 

the following sections and are presented 

in more detail in the DRIA for this 

rulemaking. EPA requests comment on 

all aspects of the cost, savings, and 

benefits analysis presented here and in 

the DRIA. EPA also requests comment 

on the inputs used in these analyses as 

described in the Draft Joint TSD. 

1. Conceptual Framework for Evaluating 

Consumer Impacts 

For this proposed rule, EPA projects 

significant private gains to consumers in 

three major areas: (1) Reductions in 

spending on fuel, (2) time saved due to 

less refueling, and (3) welfare gains from 

additional driving that results from the 

rebound effect. In combination, these 

private savings, mostly from fuel 

savings, appear to outweigh by a large 

margin the costs of the program, even 

without accounting for externalities. 

Admittedly, these findings pose a 

conundrum. On the one hand, 

consumers are expected to gain 

significantly from the proposed rules, as 

the increased cost of fuel efficient cars 

appears to be far smaller than the fuel 

savings (assuming modest discount 

rates). Yet fuel efficient cars are 

currently offered for sale, and 

consumers’ purchasing decisions may 

suggest a preference for lower fuel 

economy than the proposed rule 

mandates. Assuming full information 

and perfect foresight, standard 

economic theory suggests that the 

private gains to consumers, large as they 

are, must therefore be accompanied by 

a consumer welfare loss. This 

calculation assumes that consumers 

accurately predict all the benefits they 

will get from a new vehicle, even if they 

underestimated fuel savings at the time 

of purchase. Even if there is some such 

loss, EPA believes that under realistic 

assumptions, the private gains from the 

proposed rule, together with the social 

gains (in the form of reduction of 

externalities), significantly outweigh the 

costs. But EPA seeks comments on the 

underlying issue. 

The central conundrum has been 

referred to as the Energy Paradox in this 

setting (and in several others).331 In 

short, the problem is that consumers 

331 Jaffe, A.B., & Stavins, R.N. (1994). The Energy 

Paradox and the Diffusion of Conservation 

Technology. Resource and Energy Economics, 16(2), 

91–122. 

appear not to purchase products that are 

in their economic self-interest. There are 

strong theoretical reasons why this 

might be so.332 Consumers might be 

myopic and hence undervalue the longterm; they might lack information or a 

full appreciation of information even 

when it is presented; they might be 

especially averse to the short-term 

losses associated with energy efficient 

products (the behavioral phenomenon 

of ‘‘loss aversion’’); even if consumers 

have relevant knowledge, the benefits of 

energy efficient vehicles might not be 

sufficiently salient to them at the time 

of purchase. A great deal of work in 

behavioral economics identifies factors 

of this sort, which help account for the 

Energy Paradox.333 This point holds in 

the context of fuel savings (the main 

focus here), but it applies equally to the 

other private benefits, including 

reductions in refueling time and 

additional driving.334 

Considerable research suggests that 

the Energy Paradox is real and 

significant due to consumers’ inability 

to value future fuel savings 

appropriately. For example, Sanstad and 

Howarth (1994) argue that consumers 

optimize behavior without full 

information by resorting to imprecise 

but convenient rules of thumb. Larrick 

and Soll (2008) find evidence that 

consumers do not understand how to 

translate changes in miles-per-gallon 

into fuel savings (a concern that EPA is 

continuing to attempt to address).335 If 

these arguments are valid, then there 

will be significant gains to consumers of 

the government mandating additional 

fuel economy. 

The evidence from consumer vehicle 

choice models indicates a huge range of 

estimates for consumers’ willingness to 

pay for additional fuel economy. 

Because consumer surplus estimates 

from consumer vehicle choice models 

depend critically on this value, EPA 

would consider any consumer surplus 

estimates of the effect of our rule from 

such models to be unreliable. In 

addition, the predictive ability of 

consumer vehicle choice models may be 

limited. While vehicle choice models 

332 For an overview, see id. 

333 Id.; Thaler, Richard. Quasi-Rational 

Economics. New York: Russell Sage, 1993. 

334 For example, it might be maintained that at 

the time of purchase, consumers take full account 

of the time potentially saved by fuel-efficient cars, 

but it might also be questioned whether they have 

adequate information to do so, or whether that 

factor is sufficiently salient to play the proper role 

in purchasing decisions. 

335 Sanstad, A., and R. Howarth (1994). ‘‘ ‘Normal’ 

Markets, Market Imperfections, and Energy 

Efficiency.’’ Energy Policy 22(10): 811–818; Larrick, 

R.P., and J.B. Soll (2008). ‘‘The MPG illusion.’’ 

Science 320: 1593–1594.