Document ID: EPA-HQ-OAR-2004-0488-0094
Agency: epa
Document Type: Rule
Title: Protection of Stratospheric Ozone: Alternative for the Motor Vehicle Air Conditioning Sector under the Significant New Alternatives Policy (SNAP) Program
Posted Date: 2012-06-06T04:00Z

[Federal Register Volume 77, Number 109 (Wednesday, June 6, 2012)]
[Rules and Regulations]
[Pages 33315-33331]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-13189]

=======================================================================
-----------------------------------------------------------------------

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-ozone-depleting 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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

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?

[[Page 33316]]

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 vehicles\3\. Businesses in this end-use that may want to use 
CO2 in MVAC systems include:
---------------------------------------------------------------------------

    \2\ Chemical Abstracts Service [CAS] Registry: No. 124-38-9.
    \3\ This 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.
---------------------------------------------------------------------------

     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

[[Page 33317]]

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-users\5\ 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.
---------------------------------------------------------------------------

    \4\ As 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.
    \5\ As 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.
---------------------------------------------------------------------------

    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 end-uses within the sector. Substitutes that are acceptable 
subject to use restrictions may be used only in accordance with those 
restrictions.
---------------------------------------------------------------------------

    \6\ The SNAP regulations also include ``pending,'' referring to 
submissions for which EPA has not reached a determination, under 
this provision.
---------------------------------------------------------------------------

    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

[[Page 33318]]

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 SAE\7\ Standard J639 (2011 version) 
including:
---------------------------------------------------------------------------

    \7\ SAE International, formerly the Society of Automotive 
Engineers.
---------------------------------------------------------------------------

     Installation of a high pressure system warning label;
     Installation of a compressor cut-off switch; \8\ and
---------------------------------------------------------------------------

    \8\ A compressor cut-off switch causes a device to stop 
compressor operation before activation of any pressure relief 
device.
---------------------------------------------------------------------------

     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\
---------------------------------------------------------------------------

    \9\ The 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.
---------------------------------------------------------------------------

    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:
---------------------------------------------------------------------------

    \10\ Maximum 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.
---------------------------------------------------------------------------

     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

[[Page 33319]]

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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

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\
---------------------------------------------------------------------------

    \12\ This 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)
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \13\ The 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).
---------------------------------------------------------------------------

    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

[[Page 33320]]

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 cut-off 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 right-hand thread direction 
for refrigerant service containers.\14\
---------------------------------------------------------------------------

    \14\ The 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).
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \15\ HFO-1234yf was found acceptable only for MVAC systems in 
new passenger cars and light duty trucks (76 FR 17488, March 29, 
2011).
---------------------------------------------------------------------------

    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).
---------------------------------------------------------------------------

    \16\ Any 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.
---------------------------------------------------------------------------

    We evaluated potential human health and safety impacts, including 
the short- and long-term toxicity of CO2 and risk of injury 
to service personnel from high-pressure 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 
Short-Term 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

[[Page 33321]]

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).
---------------------------------------------------------------------------

    \17\ SNAP 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).
    \18\ Blackwell et. al 2006; Risk Analysis for Alternative 
Refrigerant in Motor Vehicle Air Conditioning (revised risk analysis 
made in 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.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \19\ Refers to the assessment by Blackwell, et al., 2006 (EPA-
HQ-OAR-2004-0488-0025).
---------------------------------------------------------------------------

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 Limit-Time 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
---------------------------------------------------------------------------

    \20\ PELs are based on an eight hour TWA exposure (OSHA, 1988a).
    \21\ REL-TWAs are concentrations for up to 10-hour workday 
during a 40-hour workweek (NIOSH, 2005).
    \22\ TLV-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).
    \23\ OSHA'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).
    \24\ REL-STELs are 15-minute TWA exposure limits that should not 
be exceeded at any time during a workday (NIOSH, 2005).
    \25\ TLV-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).
    \26\ NIOSH'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).
---------------------------------------------------------------------------

    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

[[Page 33322]]

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).
---------------------------------------------------------------------------

    \27\ Service 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)).
---------------------------------------------------------------------------

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\
---------------------------------------------------------------------------

    \28\ The 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.
    \29\ Unconsciousness 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.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \30\ On 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).
---------------------------------------------------------------------------

    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-occupied-volume, 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

[[Page 33323]]

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:
---------------------------------------------------------------------------

    \31\ Fully 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).
---------------------------------------------------------------------------

    ``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 build-up 
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-occupied-volume, 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

[[Page 33324]]

conditions in this final rule apply only when the ignition is on.
---------------------------------------------------------------------------

    \32\ We refer here to the SNAP rule listing HFO-1234yf 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).
    \33\ HFC-152a poses risks comparable to CO2 and other 
available refrigerants found acceptable subject to use conditions 
under SNAP (73 FR 33304; June 12, 2008).
---------------------------------------------------------------------------

    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

[[Page 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 fully-occupied 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 close-coupled 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

[[Page 33326]]

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 SNAP-acceptable 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.

[[Page 33327]]

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-for-profit 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, HFC-134a, 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.

[[Page 33328]]

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.

ACGIH, 2005a. TLVs[supreg] and BEIs[supreg] Based on the 
Documentation of the Threshold Limit Values for Chemical Substances 
and Physical Agents & Biological Exposure Indices. American 
Conference of Governmental Industrial Hygienists (ACGIH), 
Cincinnati, Ohio.
ACGIH, 2005b. Documentation of the Threshold Limit Values for 
Chemical Substances: Carbon Dioxide. American Conference of 
Governmental Industrial Hygienists (ACGIH), Cincinnati, Ohio.
Aero Medical Association, 1953. Committee on Aviation Toxicology, 
Blakiston, New York. As cited in CDC IDLH documentation for carbon 
dioxide. Available online at: http://www.cdc.gov/niosh/idlh/124389.html.
Al-Delaimy W.K., Hay S.M., Gain K.R., Jones D.T., Crane J., 2001. 
The effects of carbon dioxide on exercise-induced asthma: an 
unlikely explanation for the effects of Buteyko breathing training. 
Med J Aust. 15,174(2):64-5.
ANSI/ASHRAE, 2007. ASHRAE Standard 62.1-2007: Ventilation for 
Acceptable Indoor Air Quality. American National Standard Institute, 
American Society for Heating, Refrigerating, and Air-Conditioning 
Engineers (ASHRAE), Atlanta, GA. Available online at: http://www.sae.org/altrefrigerant/presentations/sumantran.pdf.
ASHRAE, 2006. BSR/ASHRAE Addendum to ANSI/ASHRAE Standard 34-2004--
Designation and Safety Classification of Refrigerants, Publication 
Draft. American Society for Heating, Refrigerating, and Air-
Conditioning Engineers (ASHRAE), Atlanta, GA.
Atkinson, W., 2002. Consumer Use of A/C Systems. SAE Automotive 
Alternate Refrigerant Systems Symposium 2002. Phoenix, Arizona. 
Available online at: http://www.sae.org/events/aars/2002/consumeruse.pdf.
Amin, J., B. Dienhart, and J. Wertenbach., 1999. Safety Aspects of 
an A/C System with Carbon Dioxide as Refrigerant, SAE Subcommittee 
Safety of Refrigerant Systems. Available online at: http://www.sae.org/misc/aaf99/visteon.pdf.
Birgfeld, E., 2003. Risk Analysis for CO2, HFC-152a, and 
Hydrocarbon Refrigerants in MACs, presented at The Earth 
Technologies Forum, Washington, DC, April 2003.
Beck J.G., P.J. Ohtake, and J.C. Shipherd., 1999. Exaggerated 
anxiety is not unique to CO2 in panic disorder: A 
comparison of hypercapnic and hypoxic challenges. J Abnorm Psychol 
108:473-482.
Blackwell, N., L. Bendixen, E. Birgfield., 2006. Risk Analysis for 
Alternative Refrigerant in Motor Vehicle Air Conditioning.
Brown. E.W., 1930. The value of high oxygen in preventing the 
physiological effects of noxious concentrations of carbon dioxide 
U.S. Naval Med. Bull. 132, 523-553. As cited in Wong 1992.
Bureau of Labor Statistics (BLS), 2003. ``Workplace Injuries and 
Illnesses in 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 International 
Cooperative Research Program 1234 by T. Lewandowski, Gradient 
Corporation. December 17, 2009.
DOT, Federal Aviation Authority, 1996. Allowable carbon dioxide 
concentration in transport category airplane cabins;

[[Page 33329]]

final rule. Federal Register 61(232):63951-63956. Available online 
at: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/51B4BFD4B3B081968625683A005905BE.
Dripps, R.D., J.H. Comroe, Jr., 1947. The respiratory and 
circulatory response of normal man to inhalation of 7.6 and 10.4 
percent CO2 with a comparison of the maximal ventilation 
produced by severe muscular exercise, inhalation of CO2 
and maximal voluntary hyperventilation. Am J Physiol 149:43-51. As 
cited in NIOSH, 1976 and NRC, 1996.
ERG Inc., 2009. Review of Health Impacts from Short Term Carbon 
Dioxide Inhalation Exposures. 110 Hartwell Ave. Lexington, MA 02421. 
February 18, 2009.
Froehling, J., M. Lorenz-Boernert, F. Schroeder, V. Khetarpal, S. 
Pitla. (2002) ``Component Development for CO2,'' 
presented at 2002 SAE Automotive Alternate Refrigerant Systems 
Symposium, Scottsdale, Arizona. Available online at: http://www.sae.org/events/aars/2002/froehling.pdf.
Gellhorn, E. (1936). The Effect of O2-Lack, Variations in the Carbon 
Dioxide-Content of the Inspired Air, and Hyperpnea on Visual 
Intensity Discrimination. American Journal of Physiology. 115: 679-
684.
Hunter D. (1975). The diseases of occupations. 5th ed. London: 
Hodder and Stoughton, p. 618 Jetter, J., R. Forte, and F. Delafield. 
(2001) ``Refrigerant Concentrations in Motor Vehicle Passenger 
Compartments,'' ASHRAE Transactions: Research, No. 4466, pp. 99-107.
Lambertsen, C.J. (1971). Therapeutic Gases: Oxygen, Carbon Dioxide, 
and Helium. In Drill's Pharmacology in Medicine, ed. J.R. DiPalma, 
1145-1179. New York, NY: McGraw-Hill.
NIOSH, 1976. Criteria for Document for Carbon Dioxide. NIOSH 
Publication No. 76-194.
NIOSH, 1990. Pocket Guide to Chemical Hazards. U.S. Department of 
Health and Human Services, Centers for Disease Control and 
Prevention, National Institutes for Occupational Safety and Health 
(NIOSH), Washington, DC. Available online at: http://www.cdc.gov/niosh/npg/.
NIOSH, 1996. Documentation for Immediately Dangerous to Life or 
Health Concentrations (IDLHs): Carbon dioxide. U.S. Department of 
Health and Human Services, Centers for Disease Control and 
Prevention, National Institutes for Occupational Safety and Health 
(NIOSH), Washington, DC. Available online at: http://www.cdc.gov/niosh/idlh/124389.html.
NIOSH, 2005. Pocket Guide to Chemical Hazards. U.S. Department of 
Health and Human Services, Centers for Disease Control and 
Prevention, National Institutes for Occupational Safety and Health 
(NIOSH), Washington, DC. Available online at: http://www.cdc.gov/niosh/npg/.
NRC, 1996. Spacecraft Maximum Allowable Concentrations for Selected 
Airborne Contaminants: Volume 2. Subcommittee on Spacecraft Maximum 
Allowable Concentrations, Committee on Toxicology, Board on 
Environmental Studies and Toxicology, Commission on Life Sciences, 
National Research Council (NRC). Washington, DC: National Academies 
Press. Available online at: http://archive.org/details/nasa_techdoc_19970023991.
NRC, 2007. Emergency and Continuous Exposure Guidance Levels for 
Selected Submarine Contaminants. Subcommittee on Emergency and 
Continuous Exposure Guidance Levels for Selected Submarine 
Contaminants, Committee on Toxicology, Board on Environmental 
Studies and Toxicology, National Research Council (NRC). Washington, 
DC: National Academies Press. Available online at: http://www.nap.edu/catalog.php?record_id=11170#toc.
OSHA, 1989. Carbon Dioxide, Industrial Exposure and Control 
Technologies for OSHA Regulated Hazardous Substances, Volume I of 
II, Substance A-I. Occupational Safety and Health Administration. 
Washington, DC: U.S. Department of Labor. March 1989.
OSHA, 1993. Final Rule on Air Contaminants: FR 58:35338-35351, June 
30, 1993. U.S. Department of Labor, Occupational Safety and Health 
Administration (OSHA), Washington, DC. Available online at: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=13306.
OSHA, 1996. Hazard Information Bulletin. Potential Carbon Dioxide 
(CO2) Asphyxiation Hazard When Filling Stationary Low 
Pressure CO2 Supply Systems. Available online at: http://
www.osha.gov/pls/oshaweb/owadisp.show--document?p--table=HIB--
STATIC&p--id=35791&p--search--type=CLOBTEXTPOLICY&p--search--
str=carbon+dioxide&p--text--version=FALSE#ctx1.
OSHA, 1997. Regulations (Standards--29 CFR); Table Z-1 Limits for 
Air Contaminants--1910.1000. U.S. Department of Labor, Occupational 
Safety and Health Administration (OSHA), Washington, DC. Available 
online at: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9992.
Patterson, J.L., H. Heyman, L.L. Battery, R.W. Ferguson., 1955. 
Threshold of response of the cerebral vessels of man to increases in 
blood carbon dioxide. Journal of Clinical Investigations. 34:1857-
1864.
Pine, D.S. et al., 2005. Response to 5% carbon dioxide in children 
and adolescents: relationship to panic disorder in parents and 
anxiety disorders in subjects. Arch Gen Psychiatry 62:73-80. 
Available online at: http://archpsyc.ama-assn.org/cgi/content/full/62/1/73.
Rebinger, C., 2005. Safety Concept Proposal for R744 A/C Systems in 
Passenger Cars--Update 2005. VDA Alternate Refrigerant Winter 
Meeting 2005. Saalfelden, Austria.
RISA Sicherheitsanalysen., 2002. Safety-Study for a Prototypical 
Mobile R744 A/C System. VDA Alternate Refrigerant Winter Meeting 
2002. Saalfelden, Austria.
Schaefer K.E., 1951. Studies of carbon dioxide toxicity. New London, 
CT: Navy Department, Bureau of Medicine and Surgery, Medical 
Research Laboratory, U.S. Naval Submarine Base, Vol. 10, Report 
No.181, pp. 156-189. As cited in NIOSH documentation for carbon 
dioxide. Last accessed January 23, 2009: http://www.cdc.gov/niosh/idlh/124389.html.
Sayers, J.A., R.E.A. Smith, R.L Holland, W.R. Keatinge. 1987. 
Effects of Carbon Dioxide on Mental Performance. Journal of Applied 
Physiology. 63(1):25-30.
Schneider, E.C., E. Truesdale., 1922. The effects on circulation and 
respiration of an increase in the carbon dioxide content of blood in 
man. American Journal of Physiology. 63:155-175.
Schulte, J.H., 1964. Sealed environments in relation to health and 
disease. Archives of Environmental Health. 8: 438-452.
SAE International, 2002. Surface Vehicle Standard J1052. Motor 
Vehicle Driver and Passenger Head Position.
SAE International, 2005. Surface Vehicle Standard J2683. Refrigerant 
Purity and Containment Requirements for Carbon Dioxide 
(CO2 R-744) Used in Mobile Air-Conditioning Systems.
SAE International, 2009. Surface Vehicle Standard J1739. Potential 
Failure Mode and Effect Analysis in Design (Design FMEA), Potential 
Failure Mode and Effect Analysis in Manufacturing and Assembly 
Processes (Process FMEA).
SAE International, 2011. Surface Vehicle Standard J639. Safety 
Standards for Motor Vehicle Refrigerant Vapor Compression Systems.
SAE International, 2011. Surface Vehicle Standard J2772. Measurement 
of Passenger Compartment Refrigerant Concentrations Under System 
Refrigerant Leakage Conditions.
SAE International, 2011. Surface Vehicle Standard J2773. Standard 
for Refrigerant Risk Analysis for Mobile Air Conditioning Systems.
Sumantran, V., B. Khalighi, K. Saka, and S. Fischer., 1999. An 
Assessment of Alternative Refrigerants for Automotive Applications 
based on Environmental Impact. General Motors R&D Center and Oak 
Ridge National Laboratory. Available online at: http://www.sae.org/altrefrigerant/presentations/sumantran.pdf.
U.S. EPA., 1994. SNAP Technical Background Document: Risk Screen on 
the Use of Substitutes for Class I Ozone-Depleting Substances: 
Refrigeration and Air Conditioning. Stratospheric Protection 
Division. March 1994.
U.S. EPA., 2005. Risk Analysis for Alternative Refrigerant in Motor 
Vehicle Air Conditioning.
U.S. EPA, 2010. Email from Yaidi Cancel, EPA to William Hill and 
Ward Atkinson, SAE Interior Climate Control Committee re: Minimum 
recordkeeping on SAE J1739. August 16, 2010.

[[Page 33330]]

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 Med. Oct. 
issue. pp 439-455. As cited in Wong 1992.
Wong, K.L., 1992. Carbon Dioxide. Internal Report, Johnson Space 
Center in the Group. National Aeronautics and Space Administration, 
Huston, TX. 1987.
Yang, Y., S. Changnian, and M. Sun., 1997. The effect of moderately 
increased CO2 concentration on perception of coherent 
motion. Aviat Space Environ Med 68(3):187-191.

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

0
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

0
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        Carbon dioxide    Acceptable        Engineering            Additional training
 Conditioning (New equipment     (CO2) as a        subject to use    strategies and/or      for service
 only).                          substitute for    conditions.       mitigation devices     technicians is
                                 CFC-12.                             shall be               recommended.
                                                                     incorporated such
                                                                     that in the event of
                                                                     refrigerant leaks,
                                                                     the resulting CO2
                                                                     concentrations do
                                                                     not exceed:
                                                                    The short term         In designing risk
                                                                     exposure level         mitigation
                                                                     (STEL) of 3% or        strategies and/or
                                                                     30,000 ppm averaged    devices,
                                                                     over 15 minutes in     manufacturers should
                                                                     the passenger free     factor in background
                                                                     space \1\; and;        CO2 concentrations
                                                                    The ceiling limit of    in the passenger
                                                                     4% or 40,000 ppm in    cabin potentially
                                                                     the passenger          contributed from
                                                                     breathing zone.\2\.    normal respiration
                                                                                            by the maximum
                                                                                            number of vehicle
                                                                                            occupants.
                                                                    Vehicle manufacturers  Use of the standards
                                                                     must keep records of   SAE J1052, SAE
                                                                     the tests performed    J2772, and SAE J2773
                                                                     for a minimum period   is recommended as
                                                                     of three years         additional
                                                                     demonstrating that     reference.
                                                                     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.
                                                                    The use of CO2 in      Manufacturers should
                                                                     MVAC systems must      conduct and keep on
                                                                     adhere to the          file Potential
                                                                     standard conditions    Failure Mode and
                                                                     identified in SAE      Effects Analysis in
                                                                     Standard J639 (2011    Design [Design
                                                                     version) including:    FMEA], Potential
                                                                    Installation of a       Failure Mode and
                                                                     high pressure system   Effect Analysis in
                                                                     warning label;.        Manufacturing and
                                                                    Installation of a       Assembly Process
                                                                     compressor cut-off     [Process FMEA] on
                                                                     switch; and.           the MVAC as stated
                                                                    Use of unique           in SAE J1739.
                                                                     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\.
----------------------------------------------------------------------------------------------------------------
\1\ Free space is defined as the space inside the passenger compartment excluding the space enclosed by the
  ducting in the HVAC module.
\2\ Area 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.
\3\ The 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.

[[Page 33331]]

* * * * *
[FR Doc. 2012-13189 Filed 6-5-12; 8:45 am]
BILLING CODE 6560-50-P