Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33315 

1 GWP, is defined as the ratio of heat trapped by 

one unit mass of the greenhouse gas to that of one 

unit mass of CO2 over a specified period of time. 

Consistent with the international standards under 

the United Nations Framework Convention on 

Climate Change (UNFCCC), all GWPs in this rule 

are given using a 100-year period (IPCC, 1996). 

Authority: 5 U.S.C. 552(a); 13 U.S.C 301– 

307; 18 U.S.C. 1692–1737:39 U.S.C. 101, 401, 

403, 404, 414, 416, 3001–3011, 3201–3219, 

3403–3406, 3621, 3622, 3626, 3632, 3633, 

and 5001. 

2. Revise the following sections of 

Mailing Standards of the United States 

Postal Service, Domestic Mail Manual 

(DMM), as follows: 

Mailing Standards of the United States 

Postal Service, Domestic Mail Manual 

(DMM) 

* * * * * 

700 Special Standards 

* * * * * 

707 Periodicals 

* * * * * 

12.0 Nonbarcoded (Presorted) 

Eligibility 

12.1 Basic Standards 

* * * * * 

12.1.3 Barcode Quality 

[Revise the text of 12.1.3 as follows:] 

Any Intelligent Mail barcode on a 

mailpiece must be correct for the 

delivery address and meet the standards 

in 708.4.0 and 708.3.0. 

* * * * * 

13.0 Carrier Route Eligibility 

13.1 Basic Standards 

* * * * * 

13.1.3 Barcode Quality 

[Revise the text of 13.1.3 as follows:] 

Any Intelligent Mail barcode on a 

mailpiece must be correct for the 

delivery address and meet the standards 

in 708.4.0 and 708.3.0. 

* * * * * 

14.0 Barcoded (Automation) 

Eligibility 

[Revise 14.1 to include the standards 

in current 14.1.1, with revised text as 

follows:] 

14.1 Basic Standards 

[Revise the introductory text of 14.1 as 

follows:] 

All pieces in a Periodicals barcoded 

(automation) mailing must: 

* * * * * 

[Revise the first sentence of item 

14.1.1c as follows:] 

c. Bear an accurate Intelligent Mail 

barcode encoded with the correct 

delivery point routing code, matching 

the delivery address and meeting the 

standards in 202.5.0 (for letters), 302.4.0 

(for flats), and 708.4.0. 

* * * * * 

[Delete the heading of current 14.1.1, 

and delete current 14.1.2, Enclosed 

Reply Cards and Envelopes, in its 

entirety.] 

* * * * * 

14.5 Address Standards for Barcoded 

Pieces 

* * * * * 

14.5.3 Numeric Delivery Point Barcode 

[Revise the text of 14.5.3 as follows:] 

A numeric equivalent of the delivery 

point routing code is formed by adding 

two digits directly after the ZIP+4 code. 

* * * * * 

We will publish an appropriate 

amendment to 39 CFR part 111 to reflect 

these changes. 

Stanley F. Mires, 

Attorney, Legal Policy & Legislative Advice. 

[FR Doc. 2012–13636 Filed 6–5–12; 8:45 am] 

BILLING CODE 7710–12–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 82 

[EPA–HQ–OAR–2004–0488; FRL–9668–8] 

RIN 2060–AM54 

Protection of Stratospheric Ozone: 

Alternative for the Motor Vehicle Air 

Conditioning Sector Under the 

Significant New Alternatives Policy 

(SNAP) Program 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: Pursuant to the U.S. 

Environmental Protection Agency 

(EPA)’s Significant New Alternatives 

Policy (SNAP) program, this action lists 

carbon dioxide (CO2) or R–744, as 

acceptable substitute, subject to use 

conditions, in the motor vehicle air 

conditioning (MVAC) end-use for motor 

vehicles (i.e., passenger cars, light-duty 

and heavy-duty vehicles) within the 

refrigeration and air-conditioning sector. 

This final rule only concerns the use of 

CO2 in MVAC systems designed 

specifically for the use of CO2

refrigerant. The substitute is non-ozonedepleting and therefore does not 

contribute to stratospheric ozone 

depletion. 

DATES: This final rule is effective on 

August 6, 2012. The incorporation by 

reference of a certain publication listed 

in this rule is approved by the Director 

of the Federal Register as of May 31, 

2011. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2004–0488. All 

documents in the docket are listed on 

the www.regulations.gov Web site. 

Although listed in the index, some 

information is not publicly available, 

e.g., confidential business information 

(CBI) or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

www.regulations.gov or in hard copy 

from the EPA Air and Radiation Docket, 

EPA/DC, EPA West, Room 3334, 1301 

Constitution Ave. NW., Washington, 

DC. This Public Reading Room is open 

from 8:30 a.m. to 4:30 p.m., Monday 

through Friday, excluding legal 

holidays. The telephone number for the 

Public Reading Room is (202) 566–1744, 

and the telephone number for the Air 

and Radiation Docket is (202) 566–1742. 

FOR FURTHER INFORMATION CONTACT: 

Yaidi Cancel, Stratospheric Protection 

Division, Office of Air and Radiation, 

MC 6205J, Environmental Protection 

Agency, 1200 Pennsylvania Ave. NW., 

Washington, DC 20460; telephone 

number: (202) 343–9512; fax number: 

(202) 343–2338; email address: 

cancel.yaidi@epa.gov. 

SUPPLEMENTARY INFORMATION: This final 

action provides motor vehicle 

manufacturers and their suppliers with 

a refrigerant option subject to use 

conditions for motor vehicle air 

conditioning systems for use in new 

vehicles. The refrigerant discussed in 

this action, carbon dioxide (R–744, CO2) 

is non-ozone-depleting and has a global 

warming potential (GWP) 1 of 1. 

Table of Contents 

I. Does this action apply to me? 

II. What abbreviations and acronyms are used 

in this action? 

III. How does the SNAP program work? 

A. What are the statutory requirements and 

authority for the SNAP program? 

B. What are EPA’s regulations 

implementing section 612 of the Clean 

Air Act? 

C. How do the regulations for the SNAP 

program work? 

D. Where can I get additional information 

about the SNAP program? 

IV. What is EPA’s final decision for CO2 as 

an alternative for MVAC? 

V. Why is EPA establishing these final use 

conditions for the use of CO2 in MVAC? 


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33316 Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 

2Chemical Abstracts Service [CAS] Registry: No. 

124–38–9. 

3This final action applies only to air conditioning 

systems in motor vehicles consistent with the 

definition of light duty vehicles and heavy-duty 

vehicles under 40 CFR 86.1803–01, with the 

exception of passenger busses. 

VI. Why is EPA listing CO2 acceptable subject 

to use conditions? 

VII. What is the relationship between this 

SNAP rule and other EPA rules? 

VIII. What is EPA’s response to public 

comments on the proposal? 

A. Use Conditions 

B. Risk Mitigation Strategies 

C. Industry Standards 

D. Servicing 

IX. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Constitution and 

Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer 

Advancement Act 

J. Executive Order 12898: Federal Actions 

to Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act 

X. References 

I. Does this action apply to me? 

This final rule lists carbon dioxide 

(CO2)2, also known as R–744, as an 

acceptable substitute subject to use 

conditions for use as a refrigerant in 

new motor vehicle air conditioning 

(MVAC) systems designed specifically 

for the use of CO2 refrigerant in motor 

vehicles3. Businesses in this end-use 

that may want to use CO2 in MVAC 

systems include: 

• Motor vehicle manufacturers 

• Motor vehicle air conditioning 

service and repair shops 

Regulated entities may include: 

TABLE 1—POTENTIALLY REGULATED ENTITIES, BY NORTH AMERICAN INDUSTRIAL CLASSIFICATION SYSTEM (NAICS) CODE

Category NAICS code Description of regulated entities 

Industry ..................................................................................................... 336111, 336112, 336120 Motor Vehicle Manufacturing. 

Services .................................................................................................... 811198 Vehicle Air Conditioning Repair. 

This table is not intended to be 

exhaustive, but rather a guide regarding 

entities likely to be regulated by this 

action. If you have any questions about 

whether this action applies to a 

particular entity, consult the person 

listed in the preceding section, FOR

FURTHER INFORMATION CONTACT. 

II. What abbreviations and acronyms 

are used in this action? 

ACGIH—American Conference of 

Governmental Industrial Hygienists 

ASE—National Institute for Automotive 

Service Excellence 

CAA—Clean Air Act 

CAS—Chemical Abstracts Service 

CBI—confidential business information 

CFC—chlorofluorocarbon 

CFC-12—the chemical 

dichlorodifluoromethane, CAS Reg. No. 

75–71–8 

CFD—computational fluid dynamics 

CFR—Code of Federal Regulations 

CNS—central nervous system 

CO2—carbon dioxide, CAS Reg. No. 124–38– 

9, also known as R–744 

CRP—Cooperative Research Program 

EPA—the United States Environmental 

Protection Agency 

EO—Executive Order 

FMEA—Failure Mode and Effect Analysis 

FR—Federal Register 

FTA—fault-tree analysis 

GWP—Global warming potential 

HCFC-22—the chemical 

chlorodifluoromethane, CAS Reg No. 75– 

45–6 

HCFC-142b—the chemical 1-chloro-1,1- 

difluoroethane, CAS Reg No. 75–68–3 

HFC—hydrofluorocarbon 

HFC-134a—the chemical 1,1,1,2- 

tetrafluoroethane, CAS Reg. No. 811–97–2 

HFC-152a—the chemical 1,1-difluoroethane, 

CAS Reg. No. 75–37–6 

HFO—hydrofluoroolefin 

HFO-1234yf—the chemical 2,3,3,3- 

tetrafluoroprop-1-ene, CAS Reg. No. 754– 

12–1 

IDLH—Immediately Dangerous to Life and 

Health 

MVAC—motor vehicle air conditioning 

NIOSH—National Institute for Occupational 

Safety and Health 

NODA—Announcement of Data Availability, 

formerly known as Notice of Data 

Availability 

NPRM—Notice of Proposed Rulemaking 

NTTAA—National Technology Transfer and 

Advancement Act 

ODP—ozone depletion potential 

ODS—ozone-depleting substance 

OEM—original equipment manufacturer 

OMB—the United States Office of 

Management and Budget 

OSHA—the United States Occupational 

Safety and Health Administration 

PEL—Permissible Exposure Level 

ppm—parts per million 

RDECOM—U.S. Army Research, 

Development and Engineering Command 

REL—Recommended Exposure Level 

RFA—Regulatory Flexibility Act 

SAE—SAE International, formerly the 

Society of Automotive Engineers 

SAE CRP—SAE Cooperative Research 

Program 

SBREFA—Small Business Regulatory 

Enforcement Fairness Act 

SNAP—Significant New Alternatives Policy 

STEL—Short Term Exposure Limit 

TWA—Time Weighted Average 

UMRA—Unfunded Mandates Reform Act 

III. How does the SNAP program work? 

A. What are the statutory requirements 

and authority for the SNAP program? 

Section 612 of the Clean Air Act 

(CAA) requires U.S. Environmental 

Protection Agency (EPA) to develop a 

program for evaluating alternatives to 

ozone-depleting substances (ODS). EPA 

refers to this program as the Significant 

New Alternatives Policy (SNAP) 

program. The major provisions of 

section 612 are: 

1. Rulemaking 

Section 612(c) requires EPA to 

promulgate rules making it unlawful to 

replace any class I (i.e., 

chlorofluorocarbon, halon, carbon 

tetrachloride, methyl chloroform, 

methyl bromide, and 

hydrobromofluorocarbon) or class II 

(i.e., hydrochlorofluorocarbon) 

substance with any substitute that the 

Administrator determines may present 

adverse effects to human health or the 

environment where the Administrator 

has identified an alternative that (1) 

reduces the overall risk to human health 

and the environment, and (2) is 

currently or potentially available. 

2. Listing of Unacceptable/Acceptable 

Substitutes 

Section 612(c) requires EPA to 

publish a list of the substitutes 

unacceptable for specific uses and to 

publish a corresponding list of 

acceptable alternatives for specific uses. 

The list of acceptable substitutes is 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33317 

4As defined at 40 CFR 82.104 ‘‘interstate 

commerce’’ means the distribution or transportation 

of any product between one state, territory, 

possession or the District of Columbia, and another 

state, territory, possession or the District of 

Columbia, or the sale, use or manufacture of any 

product in more than one state, territory, possession 

or District of Columbia. The entry points for which 

a product is introduced into interstate commerce 

are the release of a product from the facility in 

which the product was manufactured, the entry into 

a warehouse from which the domestic manufacturer 

releases the product for sale or distribution, and at 

the site of United States Customs clearance. 

5As defined at 40 CFR 82.172 ‘‘end-use’’ means 

processes or classes of specific applications within 

major industrial sectors where a substitute is used 

to replace an ozone-depleting substance. 

6The SNAP regulations also include ‘‘pending,’’ 

referring to submissions for which EPA has not 

reached a determination, under this provision. 

found at http://www.epa.gov/ozone/ 

snap/lists/index.html and the lists of 

‘‘unacceptable,’’ ‘‘acceptable subject to 

use conditions,’’ and ‘‘acceptable 

subject to narrowed use limits’’ 

substitutes are found in the appendices 

to 40 CFR part 82 subpart G. 

3. Petition Process 

Section 612(d) grants the right to any 

person to petition EPA to add a 

substance, add or delete use restrictions, 

or delete a substance from the lists 

published in accordance with section 

612(c). The Agency has 90 days to grant 

or deny a petition. Where the Agency 

grants the petition, EPA must publish 

the revised lists within an additional six 

months. 

4. 90-Day Notification 

Section 612(e) directs EPA to require 

any person who produces a chemical 

substitute for a class I substance to 

notify the Agency not less than 90 days 

before new or existing chemicals are 

introduced into interstate commerce for 

significant new uses as substitutes for a 

class I substance. The producer must 

also provide the Agency with the 

producer’s unpublished health and 

safety studies on such substitutes. 

5. Outreach 

Section 612(b)(1) states that the 

Administrator shall seek to maximize 

the use of federal research facilities and 

resources to assist users of class I and 

II substances in identifying and 

developing alternatives to the use of 

such substances in key commercial 

applications. 

6. Clearinghouse 

Section 612(b)(4) requires the Agency 

to set up a public clearinghouse of 

alternative chemicals, product 

substitutes, and alternative 

manufacturing processes that are 

available for products and 

manufacturing processes which use 

class I and II substances. 

B. What are EPA’s regulations 

implementing section 612 of the Clean 

Air Act? 

On March 18, 1994, EPA published 

the original rulemaking (59 FR 13044) 

which established the process for 

administering the SNAP program and 

issued EPA’s first lists identifying 

acceptable and unacceptable substitutes 

in the major industrial use sectors (40 

CFR part 82, subpart G). These sectors 

include: refrigeration and air 

conditioning; foam blowing; solvents 

cleaning; fire suppression and explosion 

protection; sterilants; aerosols; 

adhesives, coatings and inks; and 

tobacco expansion. These sectors 

comprise the principal industrial sectors 

that historically consumed the largest 

volumes of ODS. 

Section 612 of the CAA requires EPA 

to list as acceptable those substitutes 

that do not present a significantly 

greater risk to human health and the 

environment as compared with other 

substitutes that are currently or 

potentially available. 

C. How do the regulations for the SNAP 

program work? 

Under the SNAP regulations, anyone 

who produces a substitute to replace a 

class I or II ODS in one of the eight 

major industrial use sectors must 

provide notice to the Agency, including 

health and safety information on the 

substitute at least 90 days before 

introducing it into interstate commerce 

for significant new use as an alternative. 

40 CFR 82.176(a). This requirement 

applies to the person planning to 

introduce the substitute into interstate 

commerce,4 typically chemical 

manufacturers, but may also include 

importers, formulators, equipment 

manufacturers, or end-users5 when they 

are responsible for introducing a 

substitute into commerce. The 90-day 

SNAP review process begins once EPA 

receives the submission and determines 

that the submission includes complete 

and adequate data. 40 CFR 82.180(a). 

The CAA and the SNAP regulations, 40 

CFR 82.174(a), prohibit use of a 

substitute earlier than 90 days after 

notice has been provided to the Agency. 

The Agency has identified four 

possible decision categories for 

substitutes: acceptable; acceptable 

subject to use conditions; acceptable 

subject to narrowed use limits; and 

unacceptable.6 40 CFR 82.180(b).Use 

conditions and narrowed use limits are 

both considered ‘‘use restrictions’’ and 

are explained below. Substitutes that are 

deemed acceptable with no use 

restrictions (no use conditions or 

narrowed use limits) can be used for all 

applications within the relevant enduses within the sector. Substitutes that 

are acceptable subject to use restrictions 

may be used only in accordance with 

those restrictions. 

After reviewing a substitute, the 

Agency may determine that a substitute 

is acceptable only if certain conditions 

in the way that the substitute is used are 

met to minimize risks to human health 

and the environment. EPA describes 

such substitutes as ‘‘acceptable subject 

to use conditions.’’ Entities that use 

these substitutes without meeting the 

associated use conditions are in 

violation of section 612 of the Clean Air 

Act and EPA’s SNAP regulations. 40 CF 

82.174(c). 

For some substitutes, the Agency may 

permit a narrow range of use within an 

end-use or sector. For example, the 

Agency may limit the use of a substitute 

to certain end-uses or specific 

applications within an industry sector. 

The Agency requires a user of a 

narrowed use substitute to demonstrate 

that no other acceptable substitutes are 

available for their specific application 

by conducting comprehensive studies. 

EPA describes these substitutes as 

‘‘acceptable subject to narrowed use 

limits.’’ A person using a substitute that 

is acceptable subject to narrowed use 

limits in applications and end-uses that 

are not consistent with the narrowed 

use limit is using these substitutes in an 

unacceptable manner and is in violation 

of section 612 of the CAA and EPA’s 

SNAP regulations. 40 CFR 82.174(c). 

The Agency publishes its SNAP 

program decisions in the Federal 

Register (FR). EPA publishes decisions 

concerning substitutes that are deemed 

acceptable subject to use restrictions 

(use conditions and/or narrowed use 

limits), or for substitutes deemed 

unacceptable, as proposed rulemakings 

to allow the public opportunity to 

comment, before publishing final 

decisions. 

In contrast, EPA publishes substitutes 

that are deemed acceptable with no 

restrictions in ‘‘notices of acceptability,’’ 

rather than as proposed and final rules. 

As described in the preamble to the rule 

initially implementing the SNAP 

program (59 FR 13044; March 18, 1994), 

EPA does not believe that rulemaking 

procedures are necessary to list 

alternatives that are acceptable without 

restrictions because such listings neither 

impose any sanction nor prevent anyone 

from using a substitute. 

Many SNAP listings include 

‘‘comments’’ or ‘‘further information’’ to 

provide additional information on 

substitutes. Since this additional 

information is not part of the regulatory 


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33318 Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 

7SAE International, formerly the Society of 

Automotive Engineers. 

8A compressor cut-off switch causes a device to 

stop compressor operation before activation of any 

pressure relief device. 

9The refrigerant service containers fitting 

requirement applies only to refrigerant service 

containers used during servicing of the MVAC, in 

accordance with the provisions established for 

MVAC servicing under 40 CFR part 82, subpart B. 

10Maximum number of vehicle occupants 

includes the maximum number of passengers in a 

normal seating position inside the passenger 

compartment. This may vary between vehicle types. 

decision, these statements are not 

binding for use of the substitute under 

the SNAP program. However, regulatory 

requirements so listed are binding under 

other regulatory programs. The ‘‘further 

information’’ classification does not 

necessarily include all other legal 

obligations pertaining to the use of the 

substitute. While the items listed are not 

legally binding under the SNAP 

program, EPA encourages users of 

substitutes to apply all statements in the 

‘‘further information’’ column in their 

use of these substitutes. In many 

instances, the information simply refers 

to sound operating practices that have 

already been identified in existing 

industry and/or building-codes or 

standards. Thus, many of the 

statements, if adopted, would not 

require the affected user to make 

significant changes in existing operating 

practices. 

D. Where can I get additional 

information about the SNAP program? 

For copies of the comprehensive 

SNAP lists of substitutes or additional 

information on SNAP, refer to EPA’s 

Ozone Depletion Web site at 

www.epa.gov/ozone/snap/index.html. 

For more information on the Agency’s 

process for administering the SNAP 

program or criteria for evaluation of 

substitutes, refer to the SNAP final 

rulemaking published March 18, 1994 

(59 FR 13044), codified at 40 CFR part 

82, subpart G. A complete chronology of 

SNAP decisions and the appropriate 

citations are found at http:// 

www.epa.gov/ozone/snap/chron.html. 

IV. What is EPA’s final decision for CO2

as an alternative for MVAC? 

In this final rule, EPA is modifying its 

previous determination that listed CO2

as an acceptable substitute for CFC–12 

in new MVAC systems (59 FR 13044; 

March 18, 1994) and is listing CO2

acceptable, subject to use conditions, as 

a substitute for CFC–12 in new MVAC 

systems. This final action does not 

apply to the use of CO2 as a conversion 

or retrofit for existing MVAC systems. In 

addition, it does not apply to the use of 

CO2 in the air conditioning or 

refrigeration systems of buses, trains, 

rail or subway cars, or appliances such 

as refrigerated transport. This refrigerant 

may be used only in equipment 

designed specifically and clearly 

identified for this refrigerant (i.e., it may 

not be used as a conversion or ‘‘retrofit’’ 

refrigerant for existing equipment). EPA 

is not mandating the use of CO2 or any 

other alternative to ODS in MVAC 

systems. Vehicle manufacturers have 

the option of using any refrigerant listed 

as acceptable for this end-use, so long as 

they meet the applicable use conditions. 

This action removes CO2 from the list of 

acceptable substitutes for MVAC 

systems and instead lists it as acceptable 

subject to the following use conditions: 

1. Engineering strategies and/or 

mitigation devices shall be incorporated 

such that in the event of refrigerant 

leaks the resulting CO2 concentrations 

do not exceed: 

• The short term exposure level 

(STEL) of 3% or 30,000 ppm averaged 

over 15 minutes in the passenger free 

space; and 

• The ceiling limit of 4% or 40,000 

ppm in the passenger breathing zone. 

2. Vehicle manufacturers (i.e., original 

equipment manufacturers [OEMs]) must 

keep records of the tests performed for 

a minimum period of three years 

demonstrating that CO2 refrigerant 

levels do not exceed the STEL of 3% 

averaged over 15 minutes in the 

passenger free space, and the ceiling 

limit of 4% in the breathing zone. 

3. The use of CO2 in MVAC systems 

must adhere to the standard conditions 

identified in SAE7 Standard J639 (2011 

version) including: 

• Installation of a high pressure 

system warning label; 

• Installation of a compressor cut-off 

switch; 8 and 

• Use of unique fittings with: 

i. Outside diameter of 16.6 +0/¥0.2 

mm (0.6535 +0/¥0.0078 inches) for the 

MVAC low-side service port; 

ii. Outside diameter of 18.1 +0/¥0.2 

mm (0.7126 +0/¥0.0078 inches) for the 

MVAC high-side service port; and 

iii. Outside diameter of 20.955 

+0/¥0.127 mm (0.825 +0/¥0.005 

inches) and right-hand thread direction 

for CO2 refrigerant service containers.9

To help ensure that the first use 

condition is met, we are including 

several recommendations in the listing 

decision. First, OEMs should conduct 

and keep on file Failure Mode and 

Effect Analysis (FMEA) on the MVAC as 

stated in SAE J1739 (Potential Failure 

Mode and Effects Analysis in Design 

[Design FMEA], Potential Failure Mode 

and Effect Analysis in Manufacturing 

and Assembly Process [Process FMEA]), 

or equivalent. Second, OEMs should 

factor in background CO2 concentrations 

that come about from normal respiration 

by the maximum number of vehicle 

occupants.10 Third, EPA recommends 

the use of the following industry 

standards as additional references when 

locating the driver’s and passengers’ 

breathing zone consistent with the head 

and seating position, measuring 

refrigerant concentrations at different 

locations inside the passenger 

compartment including the breathing 

zone, and addressing risks associated 

with MVAC use: 

• SAE J1052—Motor Vehicle Driver 

and Passenger Head Position; 

• SAE J2772—Measurement of 

Passenger Compartment Refrigerant 

Concentrations under System 

Refrigerant Leakage Conditions; and 

• SAE J2773—Standard for 

Refrigerant Risk Analysis for Mobile Air 

Conditioning Systems. 

Fourth, EPA recommends additional 

training for MVAC service technicians 

that will service MVAC systems using 

CO2 as the refrigerant. 

V. Why is EPA establishing these final 

use conditions for the use of CO2 in new 

MVAC? 

Summary of SNAP Actions on the Use 

of CO2 as a Refrigerant in MVAC 

In the initial SNAP rulemaking issued 

on March 18, 1994 (59 FR 13044), EPA 

found CO2 acceptable as a substitute for 

CFC-12 in new MVAC systems. In that 

final rule, EPA also found other 

substitutes (i.e., HFC–134a and R–401C, 

evaporative cooling and stirring cycle) 

acceptable for use in new MVAC 

systems. On June 13, 1995 (60 FR 

31092) and October 16, 1996 (61 FR 

54040) EPA took two separate actions 

requiring the use of unique fittings for 

several refrigerants then currently listed 

as acceptable for use in new MVAC 

systems (60 FR 31092) and for 

refrigerants subsequently found 

acceptable for use in MVAC (61 FR 

54040). The use conditions requiring 

unique fittings were codified at 40 CFR 

Part 82, Subpart G, Appendix D. None 

of these actions applied to CO2. 

However, in the preamble to the October 

16, 1996 SNAP rule, EPA stated that for 

any decision made under SNAP, the 

Agency may, on its own, determine that 

additional conditions or restrictions 

should be added or removed through 

future rulemaking (61 FR 54032). Also, 

EPA stated in the October 16, 1996 

SNAP rule that due concerns about 

potential cross-contamination as a result 

of the large number of MVAC 

refrigerants, the Agency may choose to 

list a substitute as acceptable subject to 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33319 

11 In the same NPRM, EPA also proposed to find 

HFC-152a acceptable subject to use conditions. On 

June 12, 2008, EPA published a final rule listing 

HFC-152a as an acceptable substitute, subject to use 

conditions, for new MVAC (73 FR 33304), but 

deferred final ruling on the use of CO2 in new 

MVAC systems. 

12This was the location considered in the U.S. 

Army risk assessment, in addition to the rest of the 

vehicle occupant compartment (EPA–HQ–OAR– 

2004–0488–0025.2) 

13The unique fittings provision applies for MVAC 

service ports and containers intended for servicing 

of the MVAC (Appendix D to Subpart G of 40 CFR 

part 82, 61 FR 54040; October 16, 2006). 

use the conditions listed (in that rule, 

i.e., use of unique fittings) while 

proceeding with notice-and-comment 

rulemaking to impose other restrictions 

(61 FR 54034). 

Although the initial SNAP rulemaking 

listed CO2 as acceptable for use in new 

MVAC systems, at that time, EPA was 

not aware of any interest in using CO2

in MVAC systems and did not receive 

any submission for unique fittings to be 

used on CO2 MVAC systems or any 

information specified in 40 CFR Part 82, 

Subpart G, Appendix D. EPA was 

subsequently made aware through risk 

screens of concerns regarding health 

risks to exposure of CO2 from refrigerant 

leaks into the passenger compartment 

(EPA–HQ–OAR–2004–0488–0025.2). 

EPA was also made aware of potential 

interest in using CO2 as a refrigerant for 

MVAC systems and of technology being 

developed (71 FR 55141; September 21, 

2006). On September 21, 2006, we 

issued a Notice of Proposed Rulemaking 

(referred to hereinafter as ‘‘the 

proposal’’ or NPRM) proposing to find 

CO2 acceptable as a substitute for CFC– 

12 in new MVAC systems, subject to the 

use conditions specified at 40 CFR part 

82, subpart G, appendix D (71 FR 

55140). In addition, due to concerns 

regarding the possibility of driver 

performance decrement and adverse 

effects on passengers if exposed to 

concentrations of CO2 above 3% during 

a short period of time (e.g., 15 minutes), 

we proposed use conditions restricting 

CO2 refrigerant concentrations to a STEL 

of 3% averaged over 15 minutes in the 

passenger free space caused by leaks 

from the MVAC.11 Subsequently, on 

September 17, 2009 (74 FR 47774), EPA 

issued a notice of data availability 

(NODA) making available to the public 

additional information received 

supporting a ceiling limit of 4% CO2 as 

a level that should not be exceeded for 

any period of time due to possible 

adverse health effects. We also 

requested public comment on whether 

EPA should include in a final rule, 

listing CO2 as acceptable subject to use 

conditions for new MVAC systems, a 

ceiling limit of 4% CO2 in addition to 

the proposed STEL of 3% averaged over 

15 minutes inside the passenger 

compartment, and whether the 

proposed use conditions should apply 

when the ignition is off. 

Basis for Use Conditions Included in 

This Final Rule 

EPA proposed three use conditions in 

the NPRM. One use condition required 

that systems be designed to avoid 

occupant exposure to CO2

concentrations above a STEL of 3% CO2

averaged over 15 minutes in the 

passenger free space, during the event of 

a leak. The passenger free space is the 

space inside the passenger compartment 

excluding the space enclosed by the 

ducting in the HVAC module (71 FR 

55149). The proposal also stated that a 

breathing zone ceiling limit may 

provide additional assurance regarding 

vehicle driver alertness and requested 

comment on whether a maximum limit 

should be applied in the driver and 

passenger breathing zone, in addition to 

the 3% CO2 free space limit averaged 

over 15 minutes. In the NODA, we 

defined the breathing zone as the space 

where people breathe (74 FR 47775), 

and data received during the public 

comment period defined this zone as 

the area inside the passenger 

compartment where the driver’s and 

passengers’ heads are located during a 

normal sitting position.12

The other proposed use conditions 

required OEMs to: (1) Keep records of 

the test performed to ensure that MVAC 

systems are safe and designed with 

sufficient safety mitigation devices so 

that occupants are not exposed to levels 

above the CO2 STEL; and (2) adhere to 

all the safety requirements listed in the 

SAE Standard J639, in addition to the 

use conditions already established 

under Appendix D to Subpart G of 40 

CFR part 82, for MVAC substitutes: 

unique fittings,13 label, and a 

compressor cut-off switch. 

We received a number of public 

comments on the proposed use 

conditions and subsequent data 

announced in the NODA regarding the 

4% CO2 ceiling limit. Some commenters 

claimed that the proposed STEL of 3% 

CO2 averaged over 15 minutes was 

enough to protect passengers and ensure 

driver alertness (EPA–HQ–OAR–2004– 

0448–0025.1, –0032, –0044). Other 

commenters stated that there are 

sufficient arguments for choosing 

percent concentration limits higher than 

the proposed STEL of 3% CO2 averaged 

over 15 minutes (EPA–HQ–OAR–2004– 

0448–0043, –0049). Alternatively, some 

commenters requested a maximum CO2

ceiling limit in the passenger breathing 

zone (EPA–HQ–OAR–2004–0448–0030, 

–0035, –0047.1) and one commenter 

considered appropriate the 4% CO2

ceiling limit as an additional use 

condition (EPA–HQ–OAR–2004–0448– 

0047.1). 

After considering the information in 

the docket at the time of proposal, 

comments received on the proposed 

rule, and additional information we 

have received in response to the NODA, 

we have decided to finalize the use 

conditions as proposed in the 

September 21, 2006, NPRM, and to add 

a ceiling limit of 4% CO2, which would 

apply in addition to the 3% averaged 

over 15-minute CO2 STEL. We believe 

that requiring a CO2 ceiling limit is 

necessary because it is possible for a 

time-weighted average concentration, 

such as the STEL, to be under 3%, while 

peak concentrations could reach higher 

limits resulting in possible hearing and 

vision effects that could distract and 

endanger a driver, or cause other, 

potentially more severe adverse health 

effects (EPA–HQ–OAR–2004–0488– 

0041). Thus, the proposed use condition 

requiring mitigation strategies for 

MVAC systems, to prevent leaks of CO2

refrigerant reaching concentrations 

above 3% averaged over 15 minutes 

inside the passenger compartment free 

space, may not be sufficient on its own 

to protect drivers and passengers. This 

further protective limit is necessary to 

ensure that overall risks to human 

health and the environment from CO2

will be similar to or less than those of 

other available refrigerants that EPA has 

already listed as acceptable for MVAC. 

In the final rule, we also revised the 

proposed use condition on 

recordkeeping to refer to the 4% ceiling 

limit. The September 21, 2006 NPRM 

proposed requiring OEMs to keep 

records demonstrating they have met 

the use condition requiring safety 

mitigation devices to avoid occupant 

exposure above the 3% CO2 STEL in the 

passenger compartment. The final use 

condition addressing recordkeeping 

requires OEMs to keep records of the 

tests performed for a minimum period 

of three years demonstrating that MVAC 

systems are designed incorporating 

engineering devices or mitigation 

strategies so that in the event of 

refrigerant leak, the resulting 

concentrations of CO2 in the passenger 

free space do not exceed the STEL of 

3% averaged over 15 minutes and do 

not exceed the ceiling limit of 4% in the 

passenger breathing zone. Keeping 

records of tests performed evaluating 

system safety is a customary practice for 

OEMs while vehicles are in production 


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33320 Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 

14The SAE J639 standard specifies unique fittings 

for high-side and low-side service ports and makes 

reference to SAE J2683 ‘‘Refrigerant Purity and 

Container requirements for Carbon Dioxide (CO2 R– 

744) Used in Mobile Air Conditioning Systems’’ 

which specifies that the unique fitting for CO2

refrigerant service containers must be consistent 

with the Cylinder Gas Association’s fitting CGA 320 

(for 0–3000 psi) which has an outside diameter of 

0.825 +0/-0.005 inches (20.955 +0/¥0.127 mm) and 

right-hand thread direction (EPA–HQ–OAR–2004– 

0488–0059, –0060). 

15HFO-1234yf was found acceptable only for 

MVAC systems in new passenger cars and light 

duty trucks (76 FR 17488, March 29, 2011). 

16Any refrigerant can act as an asphyxiant by 

limiting available oxygen in a space. When oxygen 

levels in air are reduced to 12–14% by 

displacement, symptoms of asphyxiation, loss of 

concentration, increased pulse rate and deeper 

respiration will occur. 

17SNAP rule listing as acceptable subject to use 

conditions HFO-1234yf for MVACs in new 

passenger cars and light-duty vehicles (76 FR 

17488, March 29, 2011). 

18Blackwell et. al 2006; Risk Analysis for 

Alternative Refrigerant in Motor Vehicle Air 

Conditioning (revised risk analysis made in 

and for several years afterward (EPA– 

HQ–OAR–2004–0488–0057). 

For purposes of the final rule, we are 

referencing to the 2011 version of SAE 

J639 instead of the 2005 version 

referenced in the proposed rule. The 

SAE J639 2011 version added new 

provisions designed specifically to 

address use of another refrigerant, HFO– 

1234yf (EPA–HQ–OAR–2004–0488– 

0059). The provisions under the 2011 

version of SAE J639 for high pressure 

system warning label, compressor cutoff switch, and unique fittings, remain 

unchanged. Consistent with the 

proposed rule, the criteria for 

uniqueness of fittings under Appendix 

H to Subpart G of 40 CFR Part 82, and 

the provisions of Appendix D to Subpart 

G of 40 CFR Part 82 and SAE J639 (2011 

version), in this final rule we specify 

that the CO2 refrigerant fittings must 

have: (1) An outside diameter of 16.6 

+0/¥0.2 mm (0.6535 +0/¥0.0078 

inches) for the MVAC low-side, (2) an 

outside diameter of 18.1 +0/¥0.2 mm 

(0.7126 +0/¥0.0078 inches) for the 

MVAC high-side, and (3) an outside 

diameter of 20.955 +0/¥0.127 mm 

(0.825 +0/¥0.005 inches) and righthand thread direction for refrigerant 

service containers.14

VI. Why is EPA listing CO2 acceptable 

subject to use conditions? 

EPA is listing CO2 acceptable subject 

to use conditions because the use 

conditions are necessary to ensure that 

use of CO2 will not present greater risk 

to human health and the environment 

than other available substitutes 

acceptable for use in new MVAC 

systems. Examples of other substitutes 

that EPA has already found acceptable 

subject to use conditions for use in new 

MVAC systems include HFC-152a and 

HFO-1234yf.15 A list of acceptable 

substitutes subject to use conditions for 

use in new MVAC systems can be found 

at Appendix B to Subpart G of 40 CFR, 

Part 82 and http://www.epa.gov/ozone/ 

snap/refrigerants/lists/mvacs.html. 

EPA is requiring the use of unique 

fittings for CO2 refrigerant consistent 

with Appendix D to Subpart G of 40 

CFR part 82 (61 FR 54040; October 16, 

1996). All acceptable substitutes for use 

in MVAC systems are subject to those 

use conditions (and thus are identified 

as acceptable subject to use conditions). 

For CO2, the unique fittings that must be 

used for MVAC systems are those 

identified in the industry standard SAE 

J639 (2011 version). 

In addition to the use conditions 

regarding unique fittings, EPA is 

requiring OEMs to adhere to all the 

safety requirements of SAE J639 (2011 

version) for the safe design of new 

MVAC systems using CO2. We are 

establishing this as a use condition to 

ensure that new MVAC systems that use 

CO2 are specifically designed to 

minimize release of the refrigerant into 

the passenger cabin. Adherence to the 

standard will minimize the risks that 

CO2 refrigerant levels in the passenger 

compartment and breathing zone would 

exceed the CO2 limits of 3% averaged 

over 15 minutes in the passenger cabin 

free space and the 4% ceiling limit in 

the passenger breathing zone. 

Environmental Impacts 

EPA finds that CO2 does not pose 

greater risk to the environment than 

other substitutes that are currently 

available in the end-use being evaluated 

in this rulemaking. In at least one 

aspect, CO2 is significantly better for the 

environment than most alternatives 

currently listed as acceptable subject to 

use conditions in the MVAC end-use. 

CO2 has a hundred-year time horizon 

(100-yr) global warming potential (GWP) 

of one, compared with a GWP of four for 

HFO-1234yf, 124 for HFC-152a, and 

1,430 for HFC-134a. Further, CO2 has an 

ozone depletion potential (ODP) of zero, 

comparable to HFO-1234yf, HFC-152a, 

and HFC-134a. Other SNAP-approved 

refrigerant blends containing HCFCs 

have ODPs ranging from 0.065 to 0.022. 

Additionally, CO2 is excluded from the 

definition of volatile organic compound 

(VOC) under CAA regulations (see 40 

CFR 51.100(s)). 

Human Health and Safety Impacts 

Carbon dioxide is not flammable, 

similar to HFC-134a and most other 

acceptable alternatives for MVACs. 

Therefore, it does not add risks of fire 

in a vehicle when used. For the MVAC 

end-use, the EPA has listed two 

flammable alternatives (HFC-152a and 

HFO-1234yf) acceptable, subject to use 

conditions to mitigate flammability 

risks. 

CO2 is an asphyxiant that obstructs 

the oxygen flow into the body (OSHA, 

1996; as cited in EPA–HQ–OAR–2004– 

0488–0041). However, it is not the only 

gas that may cause asphyxia. Releasing 

almost any gas 16 into an unventilated or 

poorly ventilated space can lower the 

oxygen concentration to a level that 

poses significant health risks (EPA–HQ– 

OAR–2004–0488–0041). Health risks 

could occur to drivers or vehicle 

occupants during release of CO2

refrigerant into the passenger 

compartment. Additionally, 

occupational risks could occur during 

the manufacture of the refrigerant, 

initial installation of the refrigerant into 

the MVAC system at the vehicle 

assembly plant, servicing of the MVAC 

system, or final disposition of the 

MVAC system (i.e., recycling or 

disposal). 

We evaluated potential human health 

and safety impacts, including the shortand long-term toxicity of CO2 and risk 

of injury to service personnel from highpressure CO2 MVAC systems, and 

considered detailed risk assessments 

with fault-tree analysis (FTA), (EPA– 

HQ–OAR–2004–0488–0017, –0022, and 

–0025.2), scientific data provided in 

public comments (EPA–HQ–OAR– 

2004–0488–0037.1) and other 

information obtained during the notice 

of data availability (EPA–HQ–OAR– 

2004–0488–0041). We also reviewed a 

risk assessment with fault-tree analysis 

from the SAE Corporate Research 

Program (CRP) for HFO-1234yf and CO2, 

submitted during the public comment 

period for another SNAP rulemaking 17

(EPA–HQ–OAR–2004–0488–0051, EPA– 

HQ–OAR–2008–0664–0008, and –0056). 

We also evaluated and provided 

additional information on the health 

effects and risks to CO2 exposure 

through a contractor-authored report 

‘‘Review of Health Impacts from ShortTerm Carbon Dioxide Inhalation 

Exposures’’ (EPA–HQ–OAR–2004– 

0488–0041). This report revealed that 

exposures over 4% (40,000 ppm) CO2

are likely to cause discomfort and signs 

of intoxication that could impair the 

driver’s response to road and driving 

conditions, and could create safety and 

health risks to the passengers. In 

addition to this report, a revised risk 

analysis performed by the U.S. Army 

Research, Development and Engineering 

Command (herein referred as U.S. Army 

risk analysis),18 submitted during the 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33321 

collaboration with EPA and several stakeholders, 

EPA–HQ–OAR–2004–0488–0025.2). The original 

risk screen referred in the NRPM (71 FR 55140) 

contained technical errors (EPA–HQ–OAR–2004– 

0488–0017). This final rule relies on the results of 

the revised U.S. Army risk analysis. 

19Refers to the assessment by Blackwell, et al., 

2006 (EPA–HQ–OAR–2004–0488–0025). 

20PELs are based on an eight hour TWA exposure 

(OSHA, 1988a). 

21REL–TWAs are concentrations for up to 10- 

hour workday during a 40-hour workweek (NIOSH, 

2005). 

22TLV–TWAs are concentrations for an eight 

hour workday and a 40-hour workweek, to which 

is believed that nearly all workers may be 

repeatedly exposed, day after day, for a working 

lifetime without adverse effect (ACGIH, 2005). 

23OSHA’s PEL–TWA, NIOSH’s REL–TWA, and 

ACGIH’S TLV–TWA are all the same, 5,000 ppm 

(0.5%), for CO2 (EPA–HQ–OAR–2004–0488–0041). 

24REL–STELs are 15-minute TWA exposure 

limits that should not be exceeded at any time 

during a workday (NIOSH, 2005). 

25TLV–STELs are 15-minute exposure that 

should not be exceeded at any time during a 

workday, even if the eight hour TWA is within the 

TLV–TWA (ACGIH, 2005). 

26NIOSH’s REL–STEL, and ACGIH’S TLV–STEL 

for CO2 are all 30,000 ppm (3%) 15-minute TWA 

(EPA–HQ–OAR–2004–0488–0041). 

public comment period, indicated that 

limiting passenger exposure to 4% CO2

is sufficiently protective to avoid 

serious or irreversible health effects in 

potentially sensitive subpopulations 

(EPA–HQ–OAR–2004–0488–0025.2). 

Also, the U.S. Army risk analysis 

selected the 4% CO2 level based on the 

lowest level at which performance 

decrements were observed in studies by 

Wong, 1992 (EPA–HQ–OAR–2004– 

0488–0025.2). 

Vehicle Driver and Passenger Risks 

EPA’s review of vehicle driver and 

passenger risks from CO2 refrigerant 

exposure indicated that a potential 

refrigerant leak into the vehicle 

passenger compartment is not expected 

to present an unreasonable exposure 

risk if engineering strategies or 

mitigation strategies are applied (EPA– 

HQ–OAR–2004–0488–0025, –0037.1). 

The U.S. Army risk assessment 

indicated a possible strategy to limit 

refrigerant leakage into the passenger 

compartment by installing a device 

referred as a ‘‘3-second squib valve’’ to 

discharge refrigerant to a location 

outside the passenger compartment 

three seconds after a major leak is 

detected.19 The assessment showed that 

for CO2 MVAC systems, using a squib 

valve to evacuate the charge in three 

seconds after a leak is detected kept 

passenger exposure to below levels of 

concern (i.e., 3% over 15 minutes in the 

passenger compartment, as a whole, and 

4% in the breathing zone).We listed in 

the proposal additional possible 

mitigation strategies that may reduce the 

likelihood of exceeding refrigerant 

levels of concern inside the passenger 

compartment, including within the 

breathing zone. We also received 

information from commenters on 

additional engineering strategies and 

mitigation strategies (EPA–HQ–OAR– 

2004–0488–0037.1, –0025.2, –0030, 

–0050). In this final rule, we are not 

establishing a use condition requiring a 

specific mitigation strategy, but instead 

leaving to vehicle manufacturers the 

choice of which mitigation strategy to 

use in order to ensure that in the event 

of refrigerant leak, the resulting 

concentrations of CO2 in the passenger 

free space above 3% or 30,000 ppm 

averaged over 15 minutes are avoided 

and the resulting concentrations of CO2

in the passenger breathing zone do not 

exceed the ceiling limit of 4% or 

40,000 ppm at any time. 

Occupational Risks 

EPA evaluated risks of injury and 

refrigerant exposure to workers by 

examining risk screens, published 

research information and data made 

available during the public comment 

period (EPA–HQ–OAR–2004–0017, 

–0025.2, –0041, –0022, –0015, –0051). 

We compared long-term occupational 

exposures to CO2 to a workplace 

exposure limit of 5,000 ppm (or 0.5%) 

time weighted average CO2

concentration over a period of eight 

hours, consistent with the Occupational 

Safety and Health Administration 

(OSHA) Permissible Exposure LimitTime Weighted Average (PEL–TWA),20

the Centers for Disease Control and 

Prevention’s (CDC’s) National Institute 

for Occupational Safety and Health 

(NIOSH) Recommended Exposure 

Limit-Time Weighted Average (REL– 

TWA),21 and the American Conference 

of Governmental Industrial Hygienists 

(ACGIH) Threshold Limit Value-Time 

Weighted Average (TLV–TWA).22 23

Additionally, we compared short-term 

occupational worker exposures to CO2

to a workplace short-term exposure 

limit of 30,000 ppm (or 3%) time 

weighted average CO2 concentration 

over a 15-minute period during a 

workday, consistent with NIOSH’s 

Recommended Exposure Limit-Short 

term Exposure Limit (REL–STEL) 24 and 

ACGIH’s Threshold Limit Value-Short 

Term Exposure Limit (TLV–STEL).25 26

The U.S. Army risk assessment (EPA– 

HQ–OAR–2004–0488–0025.2) evaluated 

occupational risks for the MVAC service 

sector using FTA. The FTA found 

probabilities of refrigerant exposure 

while servicing CO2 MVAC systems of 

approximately 10¥5 cases per year (i.e., 

approximately 5 annual cases per 

100,000 technicians) (EPA–HQ–OAR– 

2004–0488–0025). This figure is 

significantly lower when compared to 

the general injury and illness rate for 

auto repair technicians, which is 

approximately 4 annual cases per 100 

full time technicians (BLS, 2003; EPA– 

HQ–OAR–2004–0488–0025); thus risks 

from CO2 exposures in the MVAC 

service field are expected to be 

significantly less than the risks of injury 

already present in shops (EPA–HQ– 

OAR–2004–0488–0025). The U.S. Army 

risk assessment additionally found that 

the chances of refrigerant exposure for 

persons servicing an MVAC system do 

not vary considerably by the type of 

refrigerant used and found similar 

results for end-of-life (i.e., recycling or 

disposal) activities (EPA–HQ–OAR– 

2004–0488–0025). 

EPA notes that occupational risks 

could occur during the manufacture of 

the refrigerant and initial installation of 

the refrigerant into the MVAC system at 

the vehicle assembly plant. Although 

we did not analyze the risk of exposure 

during refrigerant manufacture and 

initial installation of CO2 refrigerant 

into the MVAC system at the vehicle 

assembly plant, we expect risks at the 

vehicle assembly plant, and at other 

workplaces were CO2 refrigerant 

handling will occur (e.g., service shops, 

and recycling or disposal facilities), to 

be similar to or lower than the risks 

from other refrigerants used for these 

purposes due to occupational safety 

practices (e.g., proper ventilation, use of 

personal protective equipment) 

established for these type of facilities 

and subject to occupational safety and 

health standards under 29 CFR Part 

1910, which are intended to address risk 

to such workers. 

Overall Conclusion 

EPA finds that the overall 

environmental and human health risks 

posed by the use of CO2 in new MVAC 

systems, subject to the use conditions 

being adopted in this final rule, is lower 

than or comparable to the risks posed by 

other substitutes found acceptable 

subject to use conditions in the same 

end-use. 

VII. What is the relationship between 

this SNAP rule and other EPA rules? 

Rules Under Sections 609 and 608 of the 

Clean Air Act 

This final SNAP rule addresses the 

conditions for safe use of CO2 in new 

MVAC systems. Thus, the requirements 

in this rule apply primarily to OEMs, 

except for specific requirements for 

unique fittings required under 

Appendix D to Subpart G of 40 CFR part 

82 which also applies for servicing of 


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27Service for consideration means receiving 

something of worth or value to perform service, 

whether in money, credit, goods, or services (see 40 

CFR 82.32 (g)). 

28The risk due to exposure to HF when using 

HFO-1234yf is approximately the same as that with 

the current use of HFC-134a (on order of 10¥12

occurrences per operating hour, or one in one 

trillion). (76 FR 17488; March 29, 2011). When this 

factor is multiplied by the approximate vehicle fleet 

and annual vehicle operating hours (250 million 

and 500 hr/yr, respectively) the occurrences per 

year are in the order of 10¥1. 

29Unconsciousness caused by short term 

exposure (e.g., 2–3 minutes) of CO2 concentration 

ranging from 7 to 10% was reported in studies by 

Aero Medical Association (1953), Flury and Zernik 

(1931), Hunter (1975), Schaefer (1951), and NIOSH 

(1996), as cited in Review of Health Impacts for 

Short-Term Carbon Dioxide Inhalation Exposures 

(2009). EPA–HQ–OAR–2004–0488–0041. 

30On March 29, 2011, EPA issued a final rule 

listing HFO-1234yf as acceptable subject to use 

conditions for MVACs in new passenger car and 

light duty trucks. One of the use conditions in that 

rule require OEMs to perform and keep on file an 

FMEA. In an FMEA vehicle designers analyze all 

the ways in which parts of the MVAC system could 

fail and identify how they will address those risks 

in design of the system. (76 FR 17488). If the FMEA 

reports that mitigation strategies are necessary in 

the MVAC for safety reasons, manufacturers are 

required to design safety components (e.g., 

mitigation strategies) to comply with the use 

condition of that rule. In the U.S. an OEM publicly 

announced that it will be using HFO-1234yf in 

some vehicles starting 2013 model year (EPA–HQ– 

OAR–2004–0488–0062). 

the MVAC. Section 609 of the CAA 

establishes standards and requirements 

regarding servicing of MVAC systems. 

These requirements include training 

and certification of any person that 

services MVAC systems for 

consideration,27 as well as standards for 

certification of equipment for refrigerant 

recovery and recycling. EPA has issued 

regulations implementing these 

statutory requirements and those 

regulations are codified at subpart B of 

40 CFR part 82. MVAC end-of-life 

disposal and recycling specifications are 

covered under section 608 of the CAA 

and our regulations are codified at 

subpart F of 40 CFR part 82. The 

statutory and regulatory provisions 

regarding MVAC servicing, refrigerant 

recovery, and refrigerant venting 

prohibition apply to any refrigerant 

alternative and are not limited to 

refrigerants that are also ODS. CO2 is 

exempted from the refrigerant venting 

prohibition provisions promulgated 

under CAA 608 (40 CFR 82.154 and 70 

FR 19278; April 13, 2005). 

VIII. What is EPA’s response to public 

comments on the proposal? 

This section summarizes EPA’s 

response to significant comments 

received during the public comment 

periods for the NPRM and the NODA. 

EPA’s response to all comments 

received can also be found in a response 

to comments document in docket EPA– 

HQ–OAR–2004–0488. 

A. Use Conditions 

Comment: Some commenters claimed 

that the proposed STEL of 3% CO2

averaged over 15 minutes in the cabin 

free space is enough to protect 

passengers and ensure driver alertness. 

One commenter suggested to consider a 

3% CO2 concentration limit averaged 

over 15 minutes in the breath level (i.e., 

breathing zone) instead of 3% in the 

cabin free space. The commenter 

considered the breathing zone to be a 

relevant point for measurement and 

claimed that high refrigerant 

concentrations lower in the vehicle 

would not impair vehicle operation. 

Other commenters supported higher 

CO2 concentration limits but over a 

shorter period of time (e.g., 5.5% CO2

for 5 minutes and 9% CO2 as a ceiling 

limit). Other commenters requested that 

EPA include a CO2 ceiling limit in the 

passenger breathing zone and one 

commenter considered appropriate a 

4% CO2 ceiling limit (i.e., a limit not to 

be exceeded at any time) as an 

additional use condition. Another 

commenter stated that use conditions 

requiring mitigation strategies are not 

necessary for low probability events 

(i.e., exceeding 4% CO2 for any 

duration) and that requiring such 

conditions would prevent the use of this 

refrigerant. 

Response: After evaluating the 

comments and risk screens (EPA–HQ– 

OAR–2004–0488–0025.2, –0041, 0051), 

EPA is revising the proposed use 

conditions to add a ceiling limit of 4% 

CO2, in addition to the CO2 STEL of 3% 

averaged over 15 minutes. We believe 

that the original proposed use condition 

requiring mitigation strategies for 

MVAC systems, to prevent leaks of CO2

refrigerant reaching concentrations 

above 3% averaged over 15 minutes 

inside the passenger compartment free 

space, may not be sufficient on its own 

to protect drivers and passengers. We 

also believe that requiring a CO2 ceiling 

limit of 4% is necessary because it is 

possible for a time-weighted average 

concentration, such as the STEL, to be 

under 3%, while peak concentrations 

could reach higher limits for a few 

minutes. As shown in published data, 

CO2 concentration peaks above 4% 

could result in effects on hearing and 

vision that could distract and endanger 

a driver, or other, potentially more 

severe adverse health effects (EPA–HQ– 

OAR–2004–0488–0041). 

CFD modeling showed that during 

unmitigated refrigerant leak scenarios, 

CO2 refrigerant concentrations in the 

passenger breathing zone can reach up 

to 10.2% in 50 seconds (0.83 minutes) 

and 8.0% in 200 seconds (3.33 minutes) 

(EPA–HQ–OAR–2004–0488–0025.2). 

The U.S. Army risk analysis’s FTA 

showed that unmitigated leak scenario 

occurrences for CO2 systems (reaching 

concentrations above 4% CO2) could 

reach 4,300 per year for the vehicle fleet 

(EPA–HQ–OAR–2004–0488–0025.2). 

These occurrences are about 10,000 

higher than the expected occurrences 

associated with leaks of a fluorinated 

refrigerant (e.g., HFC-134a, HFC-152a, or 

HFO-1234yf) breakdown product (i.e., 

hydrogen fluoride) exposure above 

health based limits.28 Several studies 

reported that exposure ranging from 7% 

to 10% CO2 for few minutes (e.g., 2–3 

minutes) resulted in loss of 

consciousness (EPA–HQ–OAR–2004– 

0488–0441).29

EPA disagrees with the commenter 

stating that use conditions requiring 

mitigation strategies are not necessary 

for low probability events and that 

requiring such conditions would 

prevent the use of this refrigerant. 

Consistent with the information above, 

we believe that unmitigated exposure 

occurrences are not rare. We believe the 

use conditions required in this final rule 

are necessary to ensure that overall risks 

to human health and the environment 

from CO2 will be similar to or less than 

those of other available refrigerants that 

EPA has already listed as acceptable for 

MVAC. We also believe that requiring 

the use conditions listed in this final 

rule would not make the refrigerant use 

less practicable. Use conditions 

imposed on other acceptable 

alternatives for MVACs (e.g., adherence 

to all safety requirements under SAE 

standard J639, use of unique fittings and 

labels, use of pressure relief devices) has 

not prevented use of such alternatives.30

Comment: Several commenters 

indicated that concentration 

measurements of CO2 inside the 

passenger compartment should consider 

passenger respiration in addition to a 

refrigerant leak from the A/C system. 

Another commenter indicated that the 

MVAC recirculation mode operates with 

at least 1% of fresh air. One commenter 

suggested changing the text of the 

proposed use condition indicating the 

STEL for CO2 refrigerant inside the 

passenger compartment to state that the 

STEL is ‘‘3% v/v fully-occupiedvolume, time averaged over 15 minutes’’ 

and to clarify that the calculation of 

such value is based on a double average 

consisting of the average CO2

concentration over the air volume of a 

fully occupied car and a time-average of 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33323 

31Fully occupied is defined as the maximum 

design occupancy determined by the number of sets 

of seat belts (EPA–HQ–OAR–2004–0488–0025.1— 

0025.2). 

32We refer here to the SNAP rule listing HFO1234yf as acceptable subject to use conditions for 

MVACs in new passenger cars and light duty 

vehicles (EPA–HQ–OAR–2008–0644, 74 FR 17488; 

March 29, 2011). 

33HFC-152a poses risks comparable to CO2 and 

other available refrigerants found acceptable subject 

to use conditions under SNAP (73 FR 33304; June 

12, 2008). 

volume-average over 15 minutes.31

Another commenter suggested 

alternative language for the use 

condition specifying a ceiling limit of 

4% CO2 applicable in any part of the 

free space inside the passenger 

compartment for a time period of 60 

seconds when the car ignition is on. The 

suggested language reads: 

‘‘Engineering strategies and/or devices 

shall be incorporated into the system 

such that foreseeable leaks into the 

passenger compartment do not result in 

R744 concentrations of 4.0% v/v or 

above in any part of the free space 

inside the passenger compartment for 

more than 60 seconds when the car 

ignition is on.’’ 

Response: EPA notes that the U.S. 

Army risk analysis assumed that a 

maximum number of passengers were in 

the vehicle before the release of 

refrigerant into the passenger 

compartment, allowing for some buildup of respiratory CO2 (EPA–HQ–OAR– 

2004–0488–0025.2). Thus, that analysis 

recognized that CO2 concentrations can 

occur from human respiration in a space 

with limited exchange of outside air and 

may consequently build up in the 

passenger cabin. For that reason, in the 

proposal, we indicated that OEMs 

should account for background CO2

concentrations in the passenger 

compartment that can result from 

human respiration when designing their 

systems and mitigation devices (71 FR 

55140; September 21, 2006). However, 

we did not specify whether the vehicle 

should be fully occupied to account for 

CO2 background concentrations. We 

believe that CO2 refrigerant 

concentrations may reach levels of 

concern (i.e., above 4% CO2) during an 

unmitigated event of refrigerant leak 

either when the vehicle is fully 

occupied or when not fully occupied 

(e.g., the vehicle is occupied by the 

driver only). Thus we do not agree with 

the commenter’s suggestion to state that 

the STEL is ‘‘3% v/v fully-occupiedvolume, time averaged over 15 

minutes’’. In this final rule, we 

recommend but do not require, 

consistent with the NPRM, to account 

for background CO2 concentrations from 

human respiration, in addition to 

refrigerant leaks when designing the 

MVAC. 

EPA notes that the proposal (79 FR 

55140; September 21, 2006) specifies 

the CO2 STEL as a concentration limit 

averaged over 15 minutes, in the event 

of a refrigerant leak. The STEL is 

determined from the sum of 

concentration and exposure time 

products (e.g., concentration 1 times 

exposure time 1 plus concentration 2 

times exposure time 2), divided by the 

total exposure time which shall not 

exceed 15 minutes (EPA–HQ–OAR– 

2004–0448–0041). Thus the STEL is a 

time-weighted average concentration 

and not necessarily a time-average of a 

volume-average as indicated by the 

commenter since STEL refers to a total 

exposure time (i.e., 15 minutes) and not 

an average time. For this reason, we do 

not agree with the commenter’s 

suggestion to clarify that the calculation 

of the 3% STEL is based on a double 

average consisting of the average CO2

concentration over the air volume of a 

fully occupied car and a time-average of 

volume-average over 15 minutes since 

the approach does not provide further 

clarity of the use condition. In this final 

rule, the CO2 STEL of 3% averaged over 

15 minutes considers the average CO2

concentration in a passenger cabin over 

a total time period of 15 minutes during 

the event of refrigerant leak; and the 

ceiling limit of 4% CO2 considers the 

total CO2 in the passenger breathing 

zone at any one moment in a passenger 

compartment during the event of a leak. 

Regarding the alternative language 

suggested by the other commenter 

specifying a ceiling limit of 4% CO2

applicable in any part of the free space 

inside the passenger compartment for a 

time period of 60 seconds when the car 

ignition is on, we note that the 

commenter did not provided 

information supporting his suggestion 

that the ceiling limit apply in areas 

other than the passenger breathing zone 

for the specified 60-second time period. 

Comment: Two commenters indicated 

the need for clarity on whether the use 

conditions apply when the ignition is 

off as well as when the ignition is on. 

Other commenters suggested 

considering the results of a risk 

assessment performed by SAE’s CRP 

indicating a significantly low 

probability for a leak when the ignition 

is off, and several other commenters 

stated that the use conditions should 

only apply when the ignition is on. 

Response: The NODA provided data 

and requested additional comment on 

whether the use conditions should 

apply when the engine is off. In 

December, 2009, after the public 

comment period closed on the NODA, 

SAE issued a report, ‘‘Risk Assessment 

for HFO-1234yf and R-744 (CO2) Phase 

III’’ (referred herein after as SAE CRP 

report), that evaluated toxicity effects 

and quantitative risks of CO2, similarly 

to the U.S. Army risk analysis. This 

report was submitted to EPA during the 

public comment period for another 

SNAP rulemaking.32 The report 

evaluates CO2 exposure estimations due 

to leaks into the passenger compartment 

during different modeled scenarios such 

as different MVAC operation mode, 

system failure, and during a collision 

(EPA–HQ–OAR–2008–0664–0056.2, 

EPA–HQ–OAR–2004–0488–0025.2, 

–0051). The SAE CRP report also 

evaluated refrigerant release into the 

passenger compartment during a 

scenario where the engine is expected to 

be off (EPA–HQ–OAR–2004–0488–0051, 

EPA–HQ–OAR–2008–0664–0056.2). For 

this scenario, which involves passengers 

sleeping inside a vehicle with the 

windows closed while refrigerant leaks 

occur, the SAE CRP report showed a 

probability for occurrences of CO2

refrigerant exposure above 6% (a 

threshold limit used by the CRP for this 

scenario) to be in the order of 10¥12 per 

vehicle/hour/occupant (EPA–HQ–OAR– 

2004–0488–0051, EPA–HQ–OAR–2008– 

0664–0056.2). We believe that 

exposures of concern inside the 

passenger compartment are more likely 

to result from a large, sudden release of 

refrigerant inside the passenger 

compartment and that such a situation 

is most likely during a collision while 

the ignition is on, as described on the 

U.S. Army risk analysis (EPA–HQ– 

OAR–2004–0488–0025.2) and consistent 

with the SAE CRP report (EPA–HQ– 

OAR–2004–0488–0051, EPA–HQ–OAR– 

2008–0664–0056.2). In addition, even if 

a rupture on the evaporator line is large, 

the overall leak rate is limited to the 

maximum flow rate of refrigerant 

through the fixed orifice tube opening of 

the MVAC (EPA–HQ–OAR–2004–0488– 

0025.2). The maximum flow rate is 

determined by the differential 

compressor discharge pressure, which is 

only available when the vehicle ignition 

is on and MVAC system is running. 

Therefore, EPA finds that the overall 

risks to human health and the 

environment from CO2 will be similar to 

or less than those of other available 

refrigerants that EPA has already listed 

as acceptable for MVAC when the 

ignition is off. Thus, consistent with a 

SNAP rule issued in June 12, 2008 (73 

FR 33304) listing HFC-152a 33 as 

acceptable subject to use conditions for 

use in new MVAC systems, the use 


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conditions in this final rule apply only 

when the ignition is on. 

Comment: One commenter suggested 

that the regulation should precisely 

define the area in the vehicle being 

regulated and indicated that SAE is 

working on a standard to establish 

standards for passenger compartment 

refrigerant concentration measurement. 

Another commenter indicated that a 

CO2 concentration limit should focus on 

the driver breathing zone rather than the 

cabin free space. 

Response: EPA has clarified the 

regulatory text of the use condition to 

define the passenger free space as the 

space inside the passenger 

compartment, excluding the space 

enclosed by the ducting in the HVAC 

module. The passenger breathing zone, 

where the ceiling limit of 4% must be 

met, is defined as the area inside the 

passenger compartment where the 

driver’s and passengers’ heads are 

located during normal sitting position 

(i.e., space where people breathe, as 

defined in the NODA (71 FR 47775; 

September 17, 2009)). Additionally, we 

note that the passenger breathing zone 

is defined in SAE J2772 and the driver’s 

head position in SAE J1052. Since the 

automotive industry often relies on 

standards for designs and assessments, 

we recommend the use of the SAE J1052 

and SAE J2772 standards as references 

for further specifications regarding the 

driver’s and passengers’ head and 

seating position and to establish the 

passenger breathing zone consistent 

with our explanation provided in 

Section V of the preamble (i.e., the area 

inside the passenger compartment 

where the driver’s and passengers’ 

heads are located during a normal 

sitting position). 

EPA disagrees with the comment 

indicating that a CO2 concentration 

limit should only focus on the driver 

breathing zone rather than the passenger 

cabin free space. Based on the risk 

analyses and available data, we include 

in this final rule a 4% ceiling limit that 

must not be surpassed at any time in the 

passenger (and driver) breathing zone 

(EPA–HQ–OAR–2004–0488–0044– 

0025.2). We also include, as proposed, 

a 3% CO2 STEL averaged over 15 

minutes in the passenger cabin free 

space as an additional protective 

measure for passenger exposure to CO2. 

As indicated by the U.S. Army risk 

assessment, sensitive subpopulations 

(e.g., elderly and children) may be 

affected from exposures to high 

concentrations of CO2 (EPA–HQ–OAR– 

2004–0488–0025.2), thus we believe it is 

necessary to set a limit that would 

address risk to all people in the 

passenger compartment and not solely 

the driver. We also take into 

consideration that passengers may not 

be in a normal sitting position all the 

time (e.g., passenger may rest in a 

reclined position) and note CO2 is 

heavier than air, thus higher 

concentrations may be found at lower 

points of the passenger cabin (EPA–HQ– 

OAR–2004–0488–0025.2, –0041, –0051). 

As indicated previously, the STEL is the 

concentration limit that people can be 

exposed continuously for a short period 

of time (i.e., 15 minutes) without 

suffering adverse health risks. For these 

reasons we include both limits (i.e., 4% 

CO2 ceiling limit in the passenger 

breathing zone and 3% CO2 averaged 

over 15 minutes in the passenger cabin 

free space) in this final rule. 

Comment: Several commenters 

suggested that a CO2 ceiling limit 

should rely on exposure time since 

potential effects of CO2 vary with both 

concentration and duration of the 

exposure. One commenter stated that if 

the ceiling limit is exceeded, it is likely 

due to collision events. 

Response: EPA agrees the health 

effects of CO2 are functions of exposures 

over time. The commenter appears to 

misunderstand what a ceiling limit is. A 

ceiling limit is a limit that shall not be 

exceeded for any period of time, thus it 

is not consistent with the concept of a 

ceiling limit to also include a period of 

time during which it cannot be 

exceeded. As explained previously, we 

believe that both a ceiling limit and a 

STEL are necessary to ensure that risks 

posed from CO2 MVAC systems are not 

greater than risks posed by other 

available MVAC systems. 

While EPA agrees with the 

commenter that collision events are the 

most likely cause of a refrigerant leak 

that could cause CO2 levels to the 

exceed the ceiling limit established in 

the use conditions, there may be other 

system failures that could cause the 

ceiling limit to be exceeded. OEMs 

should consider risks from all possible 

events in designing MVACs for use with 

CO2. 

Comment: Several commenters 

suggested considering ceiling limits of 

CO2 above 4% (e.g., 6%, 9%) based on 

studies showing that visual disturbances 

occur at concentrations of 6% CO2. They 

stated that the SAE CRP report’s 

rationale suggested a 9% CO2

concentration ceiling limit, based on 

studies showing central nervous system 

(CNS) effects at CO2 exposure 

concentrations of 10% (100,000 ppm). 

Response: Studies report that human 

exposures to 6% CO2 for periods as 

short as 2 minutes can lead to hearing 

and visual disturbances, and that 

exposures to 7.5% for 5 minutes lead to 

significant reasoning and performance 

decrements (Gellhorn, 1936; Sayers, 

1987 as cited in EPA–HQ–OAR–2004– 

0488–0041). To provide a margin of 

safety, EPA considers it necessary to 

require a ceiling limit of 4% CO2 in the 

passenger breathing zone as indicated in 

the NODA and suggested by some 

commenters, to avoid driver 

performance decrement and other 

adverse health effects on passengers. 

Comment: Several commenters said 

that the ceiling limit should rely on 

NIOSH’s Immediately Dangerous to Life 

and Health (IDLH) value of 4% CO2

based on a 30-minute exposure. 

Response: EPA disagrees with the 

commenters to the extent they are 

suggesting that the 4% limit be based on 

a 30-minute exposure. The NIOSH IDLH 

value is a worker’s exposure limit based 

on the effects that might occur as a 

consequence of a 30-minute exposure 

(NIOSH 2005; EPA–HQ–OAR–2004– 

0488–0041). The OSHA regulation 

(1910.134(b)) defines the term as ‘‘an 

atmosphere that poses an immediate 

threat to life, would cause irreversible 

adverse health effects, or would impair 

an individual’s ability to escape from a 

dangerous atmosphere.’’ We believe 

NIOSH’s IDLH is inappropriate as a 

ceiling limit for the use of CO2 as a 

refrigerant in MVACs because, as 

indicated above, a ceiling limit is a limit 

that shall not be exceeded for any 

period of time. Also, a 4% limit over 30- 

minutes would not protect drivers and 

passengers from the effects of CO2

exposure at concentrations equal or 

higher than 4%. CO2 is an asphyxiant 

that obstructs the oxygen flow into the 

body and we believe that 30-minute 

duration, in particular, where the 

person affected by such a concentration 

may be operating a vehicle and thus 

posing risk to others, creates a 

significant risk. Risk Mitigation 

Strategies 

Comment: The U.S. Army noted a 

CFD parameter error in their 2005 risk 

analysis which used an incorrect 

refrigerant leak angle in their 2005 risk 

analysis (EPA–HQ–OAR–2004–0488– 

0017). The U.S. Army corrected this 

error for purposes of their 2006 risk 

analysis by using a perpendicular leak 

angle to the rupture cross-sectional area 

(EPA–HQ–OAR–2004–0488–0025.1). 

The 2006 analysis finds that an 

unmitigated discharge of CO2, in full 

recirculation mode, results in CO2

concentration above 3% for more than 

60 minutes. The U.S. Army also 

indicated that a 3-second, rather than a 

10-second squib valve, as originally 

determined, would be needed to ensure 

that CO2 concentrations remain below 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33325 

the 3% on a 15-minute average inside 

the passenger compartment. 

Response: EPA notes that the U.S. 

Army is commenting on its own risk 

assessment performed in collaboration 

with EPA and several stakeholders, and 

referenced in the NPRM (71 FR 55140). 

We also note that the 2005 U.S. Army 

risk analysis referred in the NRPM (71 

FR 55140) contained technical errors 

(EPA–HQ–OAR–2004–0488–0017). This 

final rule relies on the results of the 

revised (2006) U.S. Army risk analysis 

submitted during the public comment 

period. 

Based on the U.S. Army revised 

assessment, we understand that, in 

order for a squib valve to be an effective 

mitigation device, the activation time of 

such device should be 3 seconds rather 

than the 10 seconds indicated in the 

original risk assessment. Since we are 

not specifying in this final rule what 

mitigation strategies must be used, we 

believe the 2006 revised risk analysis 

does not affect the use conditions 

addressed in this final rule, but may 

affect the potential risk mitigation 

strategies OEMs might apply for use 

with CO2 refrigerant. 

Comment: One commenter stated that 

secondary loop technology is not a 

viable risk mitigation strategy for CO2

because of reduced system performance 

and reduced fuel efficiency. 

Response: This final rule does not 

specify design options. EPA does not 

intend to limit engineering innovation 

by requiring any specific risk mitigation 

strategy; however, EPA notes that 

secondary loop technology could 

potentially reduce the risks of exceeding 

the ceiling limit of CO2 in the passenger 

compartment because the refrigerant 

charge stays separate from the passenger 

compartment. OEMs may choose to 

investigate secondary loops as a risk 

mitigation strategy, and would have to 

weigh the pros and cons, including any 

potential effect on fuel efficiency. 

However, even if secondary loop 

technology were not an attractive 

option, other feasible mitigation 

technologies could be applied to meet 

the use conditions of this final rule, 

such as a squib valve with a 3-second 

response time. 

Comment: One commenter indicated 

that squib valves with activation time of 

less than 10 seconds (e.g., few 

milliseconds) are available and such 

devices have been tested. Another 

commenter stated that a 10-second 

squib valve is not technically feasible 

given CO2 sensor performance. 

Additionally, the commenter stated that 

during sharp increases in CO2

concentration in the passenger 

compartment, a short activation time for 

a squib-valve would increase the 

possibility of purging the refrigerant 

from the air conditioning system to 

outside the vehicle when no leak in fact 

exists. 

Response: EPA agrees with the first 

commenter regarding the availability of 

squib valves and disagrees with the 

second commenter’s statement 

regarding feasibility of a squib valve. 

The 2006 U.S. Army risk analysis 

indicated that a squib valve is one 

effective strategy and viable engineering 

option to reduce the amount of charge 

that could potentially leak into the 

passenger compartment (EPA–HQ– 

OAR–2004–0488–0025.2). EPA notes 

that in the proposal, we intended for the 

squib valve activation time to include: 

1) the time the sensor takes to detect a 

significant leak that would cause CO2

refrigerant to enter into the passenger 

compartment, and 2) the time it takes 

for the squib valve to open (71 FR 

55140; September 21, 2006). The 2006 

U.S. Army risk assessment evaluated 

different activation times (i.e., 30, 10 

and 3 seconds) of squib valve during 

modeled scenarios of CO2 refrigerant 

leak. The results showed higher 

effectiveness of the valve preventing 

high refrigerant concentration reaching 

the passenger compartment during the 

shorter activation time. 

EPA believes that sharp increases in 

CO2 concentration in the passenger 

compartment will likely occur only 

when a significant amount of CO2

refrigerant leaks into the passenger 

compartment. Risk assessments showed 

that CO2 buildup due to passenger 

respiration occurs slowly (e.g., 60 

minutes) to levels up to 2.4% in a fullyoccupied 100 cubic feet sealed 

passenger compartment of a vehicle 

with no introduction of outside air 

(EPA–HQ–OAR–2004–0488–0025.2, 

–0041). EPA notes that a passenger 

compartment in a vehicle is not 

confined space and infiltration/ 

exfiltration rates of air changes within 

the passenger compartment and outside 

air are at least 0.3 air changes per hour 

(NREL, 2003 as cited in EPA–HQ–OAR– 

2004–0488–0025.2). Therefore, we do 

not agree that refrigerant purging from 

the air conditioning system to outside 

the vehicle will occur when no leak in 

fact exists. 

Comment: A commenter stated that 

odorants that alert drivers to a leak 

should be another option for 

compliance with the rule. 

Response: EPA did not propose the 

use of odorants, and this final action 

neither requires nor prohibits the use of 

odorants in new CO2 MVAC systems. 

Odorized CO2 may be an effective 

means to alert the driver and passengers 

to a refrigerant leak into the passenger 

compartment. However, EPA does not 

believe odorants used alone provide 

sufficient risk mitigation as it may take 

vehicle occupants a period of time to 

recognize what the odor signifies. 

Documentation has not been provided 

to show how long and how much 

odorized CO2 drivers must be exposed 

to before they recognize that the smell 

indicates a health and safety risk. 

Comment: One commenter suggested 

that EPA consider use of sensors to 

allow continuous monitoring of 

refrigerant concentration inside the 

passenger cabin as a mitigation strategy. 

Another commenter mentioned that an 

alarm system or other technical 

solutions should allow for air renewal 

and lowering concentration levels below 

the limits indicated in the use 

conditions within a reasonable time 

period 

Response: As noted previously, EPA 

is not specifying the risk mitigation 

strategies that must be used to ensure 

CO2 levels do not exceed the levels 

established in the use conditions. We do 

not believe that a sensor alone would be 

sufficient to provide effective protection 

to the passengers and to ensure that 

concentrations inside the passenger 

compartment and passenger breathing 

zone do not exceed the established CO2

concentration limits of this final rule. In 

response to the commenter stating that 

an alarm system or other technical 

solutions should allow for air renewal, 

EPA believes the use of such tool might 

be effective but that such strategy would 

need to rely on an automatic supply of 

air, rather than a driver’s response, to 

ensure CO2 concentrations do not 

exceed the exposure limits established 

in the use conditions. Thus, an 

additional mitigation device would 

need to be used in addition to any alarm 

system. 

Comment: One commenter said that 

evaporator isolation valves are not 

realistic as mitigation devices because of 

cost. The commenter stated that closecoupled and hermetically sealed 

systems are technically feasible and 

noted that an automatic increase in air 

exchange is a possible strategy that is 

technically feasible. Another commenter 

suggested that switching the MVAC 

blower to operate on outside air mode 

on high, rapidly after CO2 refrigerant is 

released, could reduce the overall 

refrigerant concentration in the 

compartment to a peak lower than 4%. 

Response: EPA believes the mitigation 

strategies mentioned by the commenters 

may all be technically feasible means to 

meet concentration levels specified in 

the use conditions. We note that in the 

proposed rule we suggested using 


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evaporator isolation valves, close 

coupled or hermetically closed systems 

that would reduce refrigerant charge 

size, and increasing air exchange (with 

outside air) in the passenger 

compartment upon detection of leaks as 

some of several potential risk mitigation 

strategies (71 FR 55140; September 21, 

2006). In this final rule we are not 

requiring a specific mitigation strategy 

or engineering device. We are allowing 

OEMs to choose a mitigation strategy 

that is consistent with the use 

conditions and that they will employ to 

protect the driver and passengers in a 

vehicle from CO2 exposure above the 

limits specified in this rule. 

Comment: One commenter stated that 

a vehicle crash could be so severe that 

the MVAC system evaporator could be 

damaged and possibly reduce a risk 

mitigation system’s effectiveness. The 

commenter proposed the inclusion of an 

evaporator crush resistance standard in 

this action. 

Response: EPA agrees that a vehicle 

crash could reduce the effectiveness of 

the risk mitigation strategy. However we 

believe that in such a case, the damage 

to the car would be so severe as to result 

in an inflow of ambient air that would 

negate the risks associated with 

potentially elevated CO2 concentrations. 

A crush-resistant evaporator could be 

selected as a possible mitigation strategy 

but, as stated previously, in this final 

rule we do not specify which 

engineering device or strategies must be 

incorporated into the MVAC system and 

leave this choice to the OEMs. 

C. Industry Standards 

Comment: Several commenters 

indicated that SAE is developing 

standards for safety and servicing of CO2

MVAC systems and that it is customary 

for OEMs to follow those standards. 

Other commenter claimed that every 

OEM is responsible for its own safety 

concept and has to show compliance 

with already existing and future safety 

standards. 

Response: EPA notes and agrees with 

the important role industry standards 

play particularly for the MVAC sector. 

In addition, we note that the regulatory 

text references the relevant SAE 

technical standards to promote 

consistency with established industry 

practices. Specifically, use conditions in 

this final rule reference SAE J639 (2011 

version). Other standards such as SAE 

J1739, which addresses design, safety, 

and recordkeeping requirements, are 

recommended to help ensure that the 

use conditions are met. 

We disagree with the comment stating 

that every OEM is responsible for its 

own safety concept because we believe 

that in addition to customary business 

standards and industry practices outside 

the scope of this rule, OEMs will 

comply with all the use conditions 

specified in this rule. 

Comment: Commenters noted that 

SAE is developing SAE J2772 standard, 

‘‘Measurement of Passenger 

Compartment Refrigerant 

Concentrations Under System 

Refrigerant Leakage Conditions’’ (EPA– 

HQ–OAR–2004–0448–0054) and SAE 

J2773 standard, ‘‘Standard for Safety 

and Risk Analysis for Use in Mobile Air 

Conditioning Systems’’ (EPA–HQ– 

OAR–2004–0448–00553), formerly 

known as Refrigerant Guidelines for 

Safety and Risk Analysis for Use in 

Mobile Air Conditioning Systems. 

Response: We note that standards 

J2772 and J2773 were recently 

published and are readily available. In 

the comments column of our listing 

decision, we recommend the use of 

J2772 and J2773 standards as well as 

other available standards such as SAE 

J1052, Motor Vehicle Driver and 

Passenger Head Position (EPA–HQ– 

OAR–2004–0448–0055). 

D. Servicing 

Comment: One commenter indicated 

CAA Section 609-certified, independent 

MVAC service technicians should be 

consulted before the rule is issued. 

Response: EPA took comments on a 

range of topics during the 60-day public 

comment period. In addition, EPA 

contacted the National Institute for 

Automotive Service Excellence (ASE), 

which represents a significant number 

of MVAC service technicians. A 

summary is in the docket for this final 

rule. ASE stated they did not see any 

servicing concerns in the proposal that 

would impact the service technicians 

they represent, but would be interested 

in any follow-on rulemaking that will 

address MVAC servicing for 

consideration under CAA Section 609 

and codified at 40 CFR part 82 subpart 

B (EPA–HQ–OAR–2004–0488–0031). 

Comment: One commenter said risks 

associated with MVAC service should 

be considered. 

Response: EPA agrees with the 

commenter and notes that risk 

associated with service were evaluated 

in the published risk analyses (EPA– 

HQ–OAR–2004–0488–0017, –0025.2, 

–0041, –0051) and discussed in the 

preamble to the proposed rulemaking 

(71 FR 55144 September 21, 2006). 

Additional details regarding our 

evaluation of risk associated with 

MVAC service can be found in Section 

VI of this final rule preamble (Why is 

EPA listing CO2 acceptable subject to 

use conditions?). As explained in more 

detail in Section VI above, we do not 

believe it is necessary to establish any 

use conditions regarding servicing 

because the overall environmental and 

human health risks posed by the use of 

CO2 in new MVAC systems, subject to 

the use conditions being adopted in this 

final rule, is lower than or comparable 

to the risks posed by other substitutes 

found acceptable subject to use 

conditions in the same end-use. 

Comment: One commenter requested 

more information on why CO2 systems 

are not found acceptable as a substitute 

in retrofitted systems. 

Response: In the original SNAP 

rulemaking (59 FR 13854; March 18, 

1994), EPA listed CO2 as an acceptable 

substitute for CFC–12 only for new 

MVAC systems. We have never received 

a SNAP submission requesting 

consideration of CO2 in retrofitted 

MVAC systems. EPA understands that 

the higher working pressure of CO2

compared to CFC–12 and other SNAPacceptable refrigerants could raise 

significant issues with retrofitting such 

systems to CO2. Because we have not 

received a request to use CO2 in 

retrofitted systems, which would 

include the technical and other analyses 

necessary to determine whether such 

use would present more risk than other 

available substitutes, this final rule only 

applies to the use of CO2 as a refrigerant 

in new MVAC systems, consistent with 

the NPRM (71 FR 55140; September 21, 

2006). When and if the Agency receives 

a submission for retrofitting to CO2, we 

will consider CO2 for use as a refrigerant 

to retrofit existing MVAC systems. 

IX. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

Under Executive Order (EO) 12866, 

(58 FR 51735; October 4, 1993) this 

action is a ‘‘significant regulatory 

action.’’ It raises novel legal or policy 

issues arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

Accordingly, EPA submitted this action 

to the Office of Management and Budget 

(OMB) for review under Executive 

Orders 12866 and 13563 (76 FR 3821, 

January 21, 2011) and any changes made 

in response to OMB recommendations 

have been documented in the docket for 

this action. 

B. Paperwork Reduction Act 

This action does not impose any new 

information collection burden under the 

Paperwork Reduction Act (44 U.S.C. 


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3501 et seq). This action is an Agency 

determination. It contains no new 

requirements for reporting. The only 

new recordkeeping requirement 

involves customary business practice. 

This rule requires minimal 

recordkeeping of studies done for three 

years to ensure that MVAC systems 

using CO2 meet the requirements set 

forth in this rule. Because it is 

customary business practice that OEMs 

conduct and keep on file records of the 

tests they perform, consistent with a 

widely recognized industry standard, 

SAE J1739 (Potential Failure Mode and 

Effect Analysis in Design [Design 

FMEA], Potential Failure Mode and 

Effect Analysis in Manufacturing and 

Assembly Processes [Process FMEA]), 

on any potentially hazardous part or 

system from the beginning of 

production of a vehicle model until 

three years or more after production of 

the model ends, we believe this 

requirement will not impose an 

additional paperwork burden. However, 

the Office of Management and Budget 

(OMB) has previously approved the 

information collection requirements 

contained in the existing regulations in 

subpart G of 40 CFR part 82 under the 

provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. and has 

assigned OMB control numbers 2060– 

0226. The OMB control numbers for 

EPA’s regulations are listed in 40 CFR 

part 9. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of today’s rule on small entities, small 

entity is defined as: (1) A small 

business, as defined by the Small 

Business Administration’s (SBA) 

regulations at 13 CFR 121.201;’’ (2) a 

small governmental jurisdiction that is a 

government of a city, county, town, 

school district or special district with a 

population of less than 50,000; and (3) 

a small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. 

After considering the economic 

impacts of this final rule on small 

entities, I certify that this action will not 

have a significant economic impact on 

a substantial number of small entities. 

This final rule modifies the current 

listing of CO2 as an acceptable 

alternative refrigerant subject to use 

conditions necessary for the safe use of 

CO2 in MVAC in new motor vehicles. 

The use conditions will need to be met 

by large entities (i.e., OEMs) that 

manufacturer motor vehicles if these 

choose to use CO2 as a refrigerant in 

new MVACs. This final rule does not 

mandate the use of CO2 as a refrigerant 

in new MVAC systems, thus will not 

impose significant requirements on 

small entities such as MVAC service 

shops. This final rule effectively ensures 

consistency with current practices in 

MVAC service shops regarding the use 

of unique fittings. It is not clear that 

there would be any cost differential 

between the unique fittings required for 

the use of CO2 and those used with the 

current automotive refrigerant, HFC134a, or other fittings that the industry 

could adopt instead, for other 

refrigerants. It is possible that the 

fittings required in the revised use 

condition will be equally or less 

expensive than those required for other 

acceptable alternative refrigerants 

because they are a standard shape and 

size and can be easily produced in a 

metal-working shop. Thus, cost impacts 

of this final rule on small entities are 

expected to be small. 

Although this final rule will not have 

a significant economic impact on a 

substantial number of small entities, 

EPA nonetheless has tried to reduce the 

impact of this rule on small entities. 

EPA has worked together with SAE 

International and with groups 

representing professional service 

technicians such as the Mobile Air 

Conditioning Society Worldwide, which 

conducts regular outreach with 

technicians and owners of small 

businesses such as retail refrigerant 

suppliers and automobile repair shops. 

D. Unfunded Mandates Reform Act 

This action contains no Federal 

mandates under the provisions of Title 

II of the Unfunded Mandates Reform 

Act of 1995 (UMRA), 2 U.S.C. 1531– 

1538 for State, local, or tribal 

governments or the private sector. This 

action does not affect State, local, or 

tribal governments. The enforceable 

requirements of this action related to 

integrating risk mitigation devices and 

documenting the safety of alternative 

MVAC systems affect only a small 

number of OEMs. The impact of this 

action on the private sector will be less 

than $100 million per year. Thus, this 

action is not subject to the requirements 

of sections 202 and 205 of the UMRA. 

This action is also not subject to the 

requirements of section 203 of UMRA 

because it contains no regulatory 

requirements that might significantly or 

uniquely affect small governments. This 

action applies directly to facilities that 

use these substances and not to 

governmental entities. 

E. Executive Order 13132: Federalism 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the States, on the 

relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in EO 

13132 (64 FR 43255, August 10, 1999). 

This regulation applies directly to 

facilities that use these substances and 

not to governmental entities. Thus, EO 

13132 does not apply to this rule. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This final rule does not have tribal 

implications, as specified in EO 13175 

(65 FR 67249, November 6, 2000). It 

does not significantly or uniquely affect 

the communities of Indian tribal 

governments, because this regulation 

applies directly to facilities that use 

these substances and not to 

governmental entities. Thus, EO 13175 

does not apply to this rule. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This final rule is not subject to the EO 

13045 (62 FR 19885, April 23, 1997) 

because it is not economically 

significant as defined in Executive 

Order 12866, and because the Agency 

does not have reason to believe the 

environmental health or safety risks 

addressed by this action present a 

disproportionate risk to children. This 

action’s health and risk assessments are 

discussed in sections VI and VIII of the 

preamble and in documents EPA–HQ– 

OAR–2004–0488–0025.2, EPA–HQ– 

OAR–2004–0488–0041 and EPA–HQ– 

OAR–2004–0488–0051 in the docket for 

this rulemaking. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This rule is not a ‘‘significant energy 

action’’ as defined in Executive Order 

13211 (66 FR 28355; May 22, 2001) 

because it is not likely to have a 

significant adverse effect on the supply, 

distribution, or use of energy. This 

action would impact manufacturers of 

CO2 MVAC systems for new vehicles. 


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Preliminary information indicates that 

these new systems are equally or more 

energy efficient than currently available 

systems in some climates. Therefore, we 

conclude that this rule is not likely to 

have any adverse effects on energy 

supply, distribution or use. 

I. National Technology Transfer 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995, Public Law 104–113, 

Section 12(d) (15 U.S.C. 272 note) 

directs EPA to use voluntary consensus 

standards in regulatory activities unless 

to do so would be inconsistent with 

applicable law or otherwise impractical. 

Voluntary consensus standards are 

technical standards (e.g., materials 

specifications, test methods, sampling 

procedures, and business practices) that 

are developed or adopted by voluntary 

consensus standards bodies. NTTAA 

directs EPA to provide Congress, 

through OMB, explanations when the 

Agency decides not to use available and 

applicable voluntary consensus 

standards. 

This rulemaking involves technical 

standards. EPA has incorporate by 

reference, the 2011 version of SAE 

standard J639 which is a voluntary 

consensus standard. This standard can 

be obtained from http://www.sae.org/ 

technical/standards/. This standard 

addresses safety and reliability issues of 

CO2 MVAC systems. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898 (59 FR 7629; 

February 16, 1994) establishes federal 

executive policy on environmental 

justice. Its main provision directs 

federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies, and activities on minority 

populations and low-income 

populations in the United States. 

EPA has determined that this final 

rule will not have disproportionately 

high and adverse human health or 

environmental effects on minority or 

low-income populations because it 

increases the level of environmental 

protection for all affected populations 

without having any disproportionately 

high and adverse human health or 

environmental effects on any 

population, including any minority or 

low-income population. The refrigerant 

CO2 is a non ozone-depleting substance 

with a GWP of 1.0. Based on the 

toxicological and atmospheric data 

described earlier, the use of CO2 subject 

to the use conditions specified in this 

final rule will not have any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority or low-income population. 

This final rule requires specific use 

conditions for MVAC systems, if motor 

vehicle manufacturers choose to market 

MVAC systems using this refrigerant 

alternative. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this rule and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A Major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). This rule 

will be effective August 6, 2012. 

X. References 

The documents below are referenced 

in the preamble. All documents are 

located in the Air Docket at the address 

listed in section titled ADDRESSES at the 

beginning of this document. Unless 

specified otherwise, all documents are 

available in Docket ID No. EPA–HQ– 

OAR–2004–0488 at http://www.

regulations.gov. 

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the Documentation of the Threshold 

Limit Values for Chemical Substances 

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ACGIH, 2005b. Documentation of the 

Threshold Limit Values for Chemical 

Substances: Carbon Dioxide. American 

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Aero Medical Association, 1953. Committee 

on Aviation Toxicology, Blakiston, New 

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Al-Delaimy W.K., Hay S.M., Gain K.R., Jones 

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ANSI/ASHRAE, 2007. ASHRAE Standard 

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Indoor Air Quality. American National 

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www.sae.org/altrefrigerant/

presentations/sumantran.pdf. 

ASHRAE, 2006. BSR/ASHRAE Addendum to 

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Atkinson, W., 2002. Consumer Use of A/C 

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Amin, J., B. Dienhart, and J. Wertenbach., 

1999. Safety Aspects of an A/C System 

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Birgfeld, E., 2003. Risk Analysis for CO2, 

HFC-152a, and Hydrocarbon Refrigerants 

in MACs, presented at The Earth 

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Beck J.G., P.J. Ohtake, and J.C. Shipherd., 

1999. Exaggerated anxiety is not unique 

to CO2 in panic disorder: A comparison 

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Blackwell, N., L. Bendixen, E. Birgfield., 

2006. Risk Analysis for Alternative 

Refrigerant in Motor Vehicle Air 

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in preventing the physiological effects of 

noxious concentrations of carbon 

dioxide U.S. Naval Med. Bull. 132, 523– 

553. As cited in Wong 1992. 

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2002,’’ December 18, 2003. 

CATAM., 1953. Aviation Toxicology, An 

Introduction to the Subject and a 

Handbook of Data. Committee on 

Aviation Toxicology, Aero Medical 

Association. The Blakiston Co.: New 

York, NY. Pp. 6–9, 31–39, 52–55, 74–79, 

110–115. As cited in Wong 1992. 

Compressed Cylinder Gas (CGA) Association, 

1999. Properties, Manufacture, Uses, and 

Special Requirements for Safe Handling. 

Carbon Dioxide. Handbook of 

Compressed Gases, 4th edition. 

Arlington, VA Klever Academy. Pages 

300–308. 

CRP, 2009. Risk Assessment for Alternative 

Refrigerants HFO-1234yf and R-744 

(CO2) Phase III. Prepared for SAE 

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Program 1234 by T. Lewandowski, 

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White, C.S.; Humm, J.H.; Armstrong, E.D.; 

Lundgren, N.P.V., 1952. Human 

tolerance to acute exposures to carbon 

dioxide. Report No. 1 Six percent carbon 

dioxide in air and in oxygen. Aviation 

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List of Subjects in 40 CFR Part 82 

Environmental protection, 

Administrative practicable and 

procedure, Air pollution control, 

Reporting and recordkeeping 

requirements, Stratospheric ozone layer. 

Dated: May 23, 2012. 

Lisa P. Jackson, 

Administrator. 

For the reasons set out in the 

preamble, 40 CFR Part 82 is amended as 

follows: 

PART 82—PROTECTION OF 

STRATOSPHERIC OZONE 

■ 1. The authority citation for part 82 

continues to read as follows: 

Authority: 42 U.S.C. 7414, 7601, 7671– 

7671q. 

Subpart G—Significant New 

Alternatives Policy Program 

■ 2. In Appendix B to Subpart G of Part 

82, add an entry to the end of the table 

for ‘‘Refrigerants-Acceptable Subject to 

Use Conditions,’’ and revise footnotes 1, 

2, and 3 to read as follows: 

Appendix B to Subpart G of Part 82— 

Substitutes Subject To Use Restrictions 

and Unacceptable Substitutes 

REFRIGERANTS-ACCEPTABLE SUBJECT TO USE CONDITIONS

Application Substitute Decision Conditions Comments 

*******

CFC–12 Motor Vehicle Air 

Conditioning (New 

equipment only).

Carbon dioxide 

(CO2) as a substitute for CFC– 

12.

Acceptable subject to use conditions.Engineering strategies and/or mitigation devices shall be incorporated such that in the event of 

refrigerant leaks, the resulting 

CO2 concentrations do not exceed: 

Additional training for service technicians is recommended. 

The short term exposure level 

(STEL) of 3% or 30,000 ppm 

averaged over 15 minutes in the 

passenger free space 1; and; 

The ceiling limit of 4% or 40,000 

ppm in the passenger breathing 

zone.2

In designing risk mitigation strategies and/or devices, manufacturers should factor in background 

CO2 concentrations in the passenger cabin potentially contributed from normal respiration by 

the maximum number of vehicle 

occupants. 

Vehicle manufacturers must keep 

records of the tests performed for 

a minimum period of three years 

demonstrating that CO2 refrigerant levels do not exceed the 

STEL of 3% averaged over 15 

minutes in the passenger free 

space, and the ceiling limit of 4% 

in the breathing zone.

Use of the standards SAE J1052, 

SAE J2772, and SAE J2773 is 

recommended as additional reference. 

The use of CO2 in MVAC systems 

must adhere to the standard conditions identified in SAE Standard 

J639 (2011 version) including: 

Installation of a high pressure system warning label; 

Installation of a compressor cut-off 

switch; and 

Use of unique fittings with: 

Outside diameter of 16.6 +0/¥0.2 

mm (0.6535 +0/¥0.0078 inches) 

for the MVAC low-side; 

Outside diameter of 18.1 +0/¥0.2 

mm (0.7126 +0/¥0.0078 inches) 

for the MVAC high-side; and 

Outside diameter of 20.955 +0/ 

¥0.127 mm (0.825 +0/¥0.005 

inches) and right-hand thread direction for CO2 refrigerant service 

containers.3

Manufacturers should conduct and 

keep on file Potential Failure 

Mode and Effects Analysis in Design [Design FMEA], Potential 

Failure Mode and Effect Analysis 

in Manufacturing and Assembly 

Process [Process FMEA] on the 

MVAC as stated in SAE J1739. 

1Free space is defined as the space inside the passenger compartment excluding the space enclosed by the ducting in the HVAC module. 2Area inside the passenger compartment where the driver’s and passengers’ heads are located during a normal sitting position. Refer to SAE 

J1052 for information on determining passenger head position. 3The refrigerant service containers fitting requirement applies only to refrigerant service containers used during servicing of the MVAC, in accordance with the provisions established for MVAC servicing under 40 CFR part 82, subpart B. 


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Federal Register / Vol. 77, No. 109 / Wednesday, June 6, 2012 / Rules and Regulations 33331 

* * * * * 

[FR Doc. 2012–13189 Filed 6–5–12; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF TRANSPORTATION 

Federal Motor Carrier Safety 

Administration 

49 CFR Part 395 

Regulatory Guidance on the 

Applicability of Property-Carrier Hoursof-Service Rules to the Driveaway 

Operation of Vehicles Designed to 

Transport Passengers 

AGENCY: Federal Motor Carrier Safety 

Administration (FMCSA), DOT. 

ACTION: Notice of regulatory guidance. 

SUMMARY: The property-carrier hours-ofservice (HOS) rules in 49 CFR 395.3 are 

applicable to drivers operating 

commercial motor vehicles designed or 

used to transport passengers on 

‘‘driveaway-towaway’’ trips, as defined 

in 49 CFR 390.5. This notice provides 

Federal and State enforcement 

personnel, and the motor carrier 

industry, with uniform guidance 

concerning these rules. 

DATES: Effective Date: This regulatory 

guidance is effective June 6, 2012. 

FOR FURTHER INFORMATION CONTACT: 

Thomas L. Yager, Chief, Driver and 

Carrier Operations Division, Federal 

Motor Carrier Safety Administration, 

1200 New Jersey Ave. SE., Washington, 

DC 20590. Email: MCPSD@dot.gov. 

Phone (202) 366–4325. 

SUPPLEMENTARY INFORMATION: 

Legal Basis 

The Motor Carrier Act of 1935 

provides that ‘‘The Secretary of 

Transportation may prescribe 

requirements for (1) qualifications and 

maximum hours of service of employees 

of, and safety of operation and 

equipment of, a motor carrier; and (2) 

qualifications and maximum hours of 

service of employees of, and standards 

for equipment of, a motor private 

carrier, when needed to promote safety 

of operation’’ [49 U.S.C. 31502(b)]. 

The Motor Carrier Safety Act of 1984 

(MCSA) confers on the Secretary the 

authority to regulate drivers, motor 

carriers, and vehicle equipment. It 

requires the Secretary to prescribe safety 

standards for commercial motor 

vehicles (CMVs). At a minimum, the 

regulations must ensure that (1) CMVs 

are maintained, equipped, loaded, and 

operated safely; (2) the responsibilities 

imposed on operators of CMVs do not 

impair their ability to operate the 

vehicles safely; (3) the physical 

condition of operators of CMVs is 

adequate to enable them to operate the 

vehicles safely; and (4) the operation of 

CMVs does not have a deleterious effect 

on the physical condition of the 

operator [49 U.S.C. 31136(a)]. The Act 

also grants the Secretary broad power to 

‘‘prescribe recordkeeping and reporting 

requirements’’ and to ‘‘perform other 

acts the Secretary considers 

appropriate’’ [49 U.S.C. 31133(a)(8) and 

(10)]. 

The Administrator of FMCSA has 

been delegated authority to carry out the 

functions vested in the Secretary by the 

Motor Carrier Act of 1935 [49 CFR 

1.73(l)], and the MCSA [§ 1.73(g)]. The 

provisions affected by this Notice of 

Regulatory Guidance are based on these 

statutes. 

Background 

This document adds regulatory 

guidance on the applicability of the 

hours-of-service (HOS) regulations for 

property-carrying drivers in 49 CFR 

395.3 to drivers of vehicles designed or 

used to transport passengers, while 

operating the vehicle on a ‘‘driveawaytowaway’’ trip as defined 49 CFR 390.5. 

These drivers often work for motor 

carriers that specialize in delivery of 

commercial motor vehicles (CMVs), and 

they do not operate CMVs to transport 

passengers on a regular basis. 

The § 390.5 definition of ‘‘driveawaytowaway’’ is ‘‘* * * an operation in 

which an empty or unladen motor 

vehicle with one or more sets of wheels 

on the surface of the roadway is being 

transported: (1) Between vehicle 

manufacturer’s facilities; (2) between a 

vehicle manufacturer and a dealership 

or purchaser; (3) between a dealership, 

or other entity selling or leasing the 

vehicle, and a purchaser or lessee; (4) to 

a motor carrier’s terminal or repair 

facility for the repair of disabling 

damage (as defined in § 390.5) following 

a crash; (5) to a motor carrier’s terminal 

or repair facility for repairs associated 

with the failure of a vehicle component 

or system; or (6) by means of a saddlemount or tow-bar.’’ 

Reason for This Notice 

Section 395.3 prescribes the primary 

HOS regulations applicable to propertycarrying drivers, and § 395.5 prescribes 

the comparable regulations for 

passenger-carrying drivers. Neither the 

term ‘‘property-carrying’’ nor 

‘‘passenger-carrying’’ is defined in these 

regulations. The FMCSA has received 

inquiries from motor carriers as to 

whether the property-carrying or 

passenger-carrying HOS rules would 

apply in driveaway situations usually 

involving the delivery of a bus, 

motorcoach, or similar CMV from the 

manufacturer or distributor to the 

dealer, or similar scenario. The Agency 

agrees that regulatory guidance is 

needed to clarify applicability of the 

HOS regulations. For the reasons 

explained above, FMCSA issues 

Regulatory Guidance Question 1 to 

§ 395.5 of the FMCSRs. 

PART 395—HOURS OF SERVICE OF 

DRIVERS 

§ 395.5 ‘‘Maximum driving time for 

passenger-carrying vehicles.’’ 

‘‘Question 1: Would a driver 

delivering an empty commercial motor 

vehicle designed or used to carry 

passengers, from the manufacturer or 

distributor to a dealer, or otherwise 

engaged in a ‘‘driveaway-towaway’’ trip 

as defined in § 390.5, be required to 

comply with the hours-of-service 

regulations for passenger-carrying 

drivers? 

Guidance: 

No. The property-carrier hours-ofservice rules in § 395.3 are applicable to 

drivers operating commercial motor 

vehicles designed or used to transport 

passengers in a ‘‘driveaway-towaway’’ 

operation, as defined in § 390.5.’’ 

Issued on: May 29, 2012. 

Anne S. Ferro, 

Administrator. 

[FR Doc. 2012–13657 Filed 6–5–12; 8:45 am] 

BILLING CODE 4910–EX–P 


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