Protection of Stratospheric Ozone: Listing of Substitutes in the Motor Vehicle Air Conditioning Sector Under the Significant New Alternatives Policy (SNAP) Program, 55140-55149 [06-7967]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 71, Number 183 (Thursday, September 21, 2006)]
[Proposed Rules]
[Pages 55140-55149]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-7967]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2004-0488; FRL-8221-5]
RIN 2060-AM54


Protection of Stratospheric Ozone: Listing of Substitutes in the 
Motor Vehicle Air Conditioning Sector Under the Significant New 
Alternatives Policy (SNAP) Program

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: Under mandate from the Clean Air Act to review and approve 
alternatives to ozone-depleting substances, the Environmental 
Protection Agency (EPA) proposes to expand and amend the list of 
acceptable substitutes for ozone-depleting substances (ODS) through the 
Significant New Alternatives Policy (SNAP) program. Substitutes 
addressed in this proposal are for the motor vehicle air conditioning 
(MVAC) end-use within the refrigeration and air-conditioning sector. 
The proposed substitutes are non ozone-depleting gases and consequently 
do not contribute to stratospheric ozone depletion.

DATES: Comments must be received on or before October 23, 2006. Any 
person interested in requesting a public hearing, must submit such 
request on or before October 6, 2006. If a public hearing is requested, 
a separate notice will be published announcing the date and time of the 
public hearing and the comment period will be extended until 30 days 
after the public hearing to allow rebuttal and supplementary 
information regarding any material presented at the public hearing. 
Inquires regarding a public hearing should be directed to the contact 
person listed below.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2004-0488, by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the online instructions for submitting comments.
     E-mail: a-and-r-Docket@epa.gov.
     Fax: (202) 566-1741.
     Mail: Environmental Protection Agency, EPA Docket Center 
(EPA/DC), Mailcode 6102T, Attention Docket ID No. EPA-HQ-OAR-2004-0488, 
1200 Pennsylvania Avenue, NW., Washington, DC 20460.
     Hand Delivery: Public Reading Room, Room B102, EPA West 
Building, 1301 Constitution Avenue, NW., Washington, DC.
    Such deliveries are only accepted during the Docket's normal hours 
of operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2004-0488. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
www.regulations.gov, including any personal information provided, 
unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit information that you consider to 
be CBI or otherwise protected through www.regulations.gov or e-mail. 
The www.regulations.gov Web site is an ``anonymous access'' system, 
which means EPA will not know your identity or contact information 
unless you provide it in the body of your comment. If you send an e-
mail comment directly to EPA without going through www.regulations.gov 
your e-mail address will be automatically captured and included as part 
of the comment that is placed in the public docket and made available 
on the Internet. If you submit an electronic comment, EPA recommends 
that you include your name and other contact information in the body of 
your comment and with any disk or CD-ROM you submit. If EPA cannot read 
your comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in www.regulations.gov or in hard copy at the Air Docket, EPA/DC, EPA 
West, Room B102, 1301 Constitution Ave., NW., Washington, DC. This 
Docket Facility 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 
Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For further information about this 
proposed rule, contact Karen Thundiyil by telephone at (202) 343-9464, 
or by e-mail at thundiyil.karen@epa.gov. Notices and rulemakings under 
the SNAP program are available on EPA's Stratospheric Ozone Web site at 
https://www.epa.gov/ozone/snap/regs. For copies of the full list of SNAP 
decisions in all industrial sectors, contact the EPA Stratospheric 
Protection Hotline at (800) 296-1996. You also can find a complete 
chronology of SNAP decisions and the appropriate Federal Register 
citations at EPA's Stratospheric Ozone Web site at https://www.epa.gov/
ozone/snap/chron.html.

SUPPLEMENTARY INFORMATION: This proposed action, if finalized, would 
provide motor vehicle manufacturers and their suppliers an additional 
refrigerant option for motor vehicle air conditioning systems. This 
proposed action would also modify the current acceptability of an 
approved substitute to include use conditions. The two refrigerants 
discussed in this proposed action are non ozone-depleting substances. 
Car manufacturers, component manufacturers and the MVAC service 
industry have all been actively engaged in the development of this 
rulemaking and are developing prototype systems with the use

[[Page 55141]]

conditions defined in this proposed rulemaking.

Table of Contents

I. Section 612 Regulatory Background
    A. Rulemaking
    B. Listing of Unacceptable/Acceptable Substitutes
    C. Petition Process
    D. 90-day Notification
    E. Outreach
    F. Clearinghouse
II. Summary of Acceptability Determinations
III. SNAP Criteria for Evaluating Alternatives
IV. Carbon Dioxide MVAC Systems
    A. Occupant Exposure
    B. Service Technician Exposure
    C. Environmental Information
    D. Acceptability Determination
V. HFC-152a MVAC Systems
    A. Toxicity and Flammability
    B. Service Technician Exposure
    C. Environmental Information
    D. Acceptability Determination
VI. Other Use Conditions Applicable to Motor Vehicle Air 
Conditioning Systems
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions that Significantly Affect 
Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
VIII. References

I. Section 612 Regulatory Background

    Section 612 of the Clean Air Act (CAA) authorizes EPA to develop a 
program for evaluating alternatives to ozone-depleting substances. EPA 
refers to this program as the Significant New Alternatives Policy 
(SNAP) program. The major provisions of section 612 are:

A. Rulemaking

    Section 612(c) requires EPA to promulgate rules making it unlawful 
to replace any class I (e.g., chlorofluorocarbon, halon, carbon 
tetrachloride, methyl chloroform, methyl bromide, and 
hydrobromofluorocarbon) or class II (e.g., 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.

B. Listing of Unacceptable/Acceptable Substitutes

    Section 612(c) also 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.

C. Petition Process

    Section 612(d) grants the right to any person to petition EPA to 
add a substance to, 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.

D. 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.

E. 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.

F. 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.
    On March 18, 1994, EPA published the original rulemaking (59 FR 
13044) which described the process for administering the SNAP program 
and issued EPA's first acceptability lists for substitutes in the major 
industrial use sectors. 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 compose the principal 
industrial sectors that historically consumed the largest volumes of 
ozone-depleting substances.
    For the purposes of SNAP, the Agency defines a ``substitute'' as 
any chemical, product substitute, or alternative manufacturing process, 
whether existing or new, intended for use as a replacement for a class 
I or class II substance. Anyone who produces a substitute must provide 
the Agency with health and safety studies on the substitute at least 90 
days before introducing it into interstate commerce for significant new 
use as an alternative. This requirement applies to substitute 
manufacturers, but may include importers, formulators, or end-users, 
when they are responsible for introducing a substitute into commerce.
    You can find a complete chronology of SNAP decisions and the 
appropriate Federal Register citations at EPA's Stratospheric Ozone Web 
site at https://www.epa.gov/ozone/snap/chron.html. This information is 
also available from the Air Docket (see Addresses section above for 
contact information).

II. Summary of Acceptability Determinations

    EPA proposes to find HFC-152a and CO2, with use 
conditions acceptable refrigerant substitutes as replacements for CFC-
12 in motor vehicle air conditioning (MVAC) systems. This determination 
applies to MVAC systems in newly manufactured vehicles. This 
acceptability determination does not apply to MVAC systems that were 
retrofitted to use HFC-134a and might be again retrofitted to either 
HFC-152a or CO2; nor to MVAC systems that initially were 
manufactured to use HFC-134a and that might be retrofitted to use HFC-
152a and CO2. The HFC-152a and CO2 acceptability 
determinations are based on the results of risk screens and national 
safety standards.
    In the original SNAP rulemaking,\1\ CO2 was found 
acceptable in new motor vehicle air conditioning systems, but EPA did 
not at that time base acceptability on use conditions now required by 
this rule. For various reasons, CO2 MVAC technology 
development took longer than anticipated and currently, no car 
manufacturer has put CO2 MVAC systems in production vehicles 
for general consumer use. However, manufacturers are developing 
prototype air conditioning (A/C) systems that use CO2 and 
HFC-152a for motor vehicles sold in some foreign and domestic markets. 
This rule would facilitate and allow commercial deployment of the new 
refrigerants, but leaves refrigerant choice to the market. Since the 
original SNAP rulemaking, the risks of CO2 in a MVAC system 
without risk mitigation

[[Page 55142]]

strategies have been explored and examined. Now, informed with a new 
risk screen, the SNAP program has determined that the risks of 
CO2 will be comparable to the risks of HFC-134a only if use 
conditions are implemented.
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    \1\ 59 FR 13044; March 18, 1994.
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    In making the acceptability determinations, EPA assessed the impact 
of both HFC-152a and CO2 systems on human health and the 
environment; the focus was on the risks of exposure to potentially 
hazardous levels of refrigerant for both vehicle occupants and vehicle 
service technicians and how those risks compare to those associated 
with use of HFC-134a in MVACs.\2\ EPA identified scenarios where there 
was potential for a leak into the passenger compartment and potential 
for technicians to be exposed during servicing. EPA's review found that 
a foreseeable worst case scenario leak into the passenger compartment 
from either HFC-152a or CO2 air conditioning systems might 
lead to passenger exposures above risk levels associated with HFC-134a 
systems. However, safety devices could be added or engineered into new 
systems so that potentially hazardous concentrations could be avoided, 
making the risk comparable to that associated with HFC-134a systems. 
Therefore, EPA is listing HFC-152a and CO2 as acceptable 
with the use condition that engineering devices or mitigation 
strategies be employed so that in the event of a leak, the resulting 
concentrations of refrigerant in the free space and vehicle occupant 
breathing zone within the interior car compartment are maintained at 
safe levels. Air conditioning systems with two or more evaporators will 
generally have larger refrigerant charges and therefore will require 
more elaborate safety mitigation devices and/or strategies. Other 
organizations and industry groups that have assessed risks associated 
with HFC-152a and/or CO2 MVAC systems have also concluded 
that risk mitigation strategies in some form are 
necessary.3 4
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    \2\ The predominant air conditioning refrigerant in newly 
manufactured motor vehicles is HFC-134a. In listing HFC-134a as an 
acceptable substitute, EPA found that exposure in motor vehicles 
would fall far below a threshold of concern (EPA, 1994).
    \3\ RISA, 2002.
    \4\ Rebinger, 2005.
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    EPA's analysis also found that the probability of potentially 
dangerous exposures is higher for service technicians than for 
passengers, but within the level of risk that technicians currently 
accept as part of their job. EPA recommends that service technicians 
receive additional training so they are knowledgeable about the 
different hazards associated with working on HFC-152a and 
CO2 systems when compared to HFC-134a systems. Consistent 
with Society of Automotive Engineer's Standard J639, prominent labeling 
of A/C systems with warning of ``High Pressure CO2'' and 
``Flammable Refrigerant'' is required. In addition, the SNAP 
regulations require unique fittings for the two A/C refrigerants which 
will prevent accidents associated with adding refrigerant to the wrong 
type of A/C system.
    The following sections present a more detailed discussion of the 
EPA's acceptability decisions for HFC-152a and CO2 MVAC 
systems. The listing decisions are summarized in Appendix B. The 
statements in the ``Comments'' column of the table in Appendix B 
provide additional information that is not legally binding under 
section 612 of the CAA. However, these statements may include 
information about binding requirements under other programs. 
Nevertheless, EPA strongly encourages users to use these substitutes in 
a manner consistent with the recommendations in the ``Comments'' 
section. In many instances, the comments simply refer to standard 
workplace safety practices that have already been identified in 
existing industry standards. Thus, many of these recommendations, if 
adopted, would not require significant changes in existing operating 
practices for the affected industry. Such recommendations should not be 
considered comprehensive with respect to legal obligations that may 
pertain to the use of the substitute.

III. SNAP Criteria for Evaluating Alternatives

    When making acceptability decisions, EPA has considered toxicity, 
flammability, the potential for occupational and general population 
exposure, and environmental effects including ozone depletion 
potential, atmospheric lifetime, impacts on local air quality, and 
ecosystem effects of the alternatives. EPA evaluated the criteria set 
forth at 40 CFR 82.180(a)(7) in determining whether HFC-152a and 
CO2 are acceptable refrigerant substitutes for CFC-12 in the 
motor vehicle air conditioning sector. The Agency has determined that 
the Clean Air Act does not authorize EPA to regulate for global climate 
change purposes (Fabricant, 2003). EPA has not yet concluded how this 
determination would affect its consideration of the global warming 
potential of substitutes under the SNAP program. Regardless, for the 
substitutes considered here, the global warming potential (GWP) of the 
alternatives was not a determinative factor in EPA's acceptable subject 
to use conditions determination. The GWP for these substitutes is well 
below that of previously approved substitutes in this sector.
    The data described below indicates that use of HFC-152a and 
CO2 with risk mitigation technologies does not pose greater 
risks compared to other substitutes approved in the MVAC sector.\5\ The 
review focused on the potential for hazardous exposures to the 
refrigerants for vehicle occupants and for service technicians.
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    \5\ The predominant substitute in the MVAC sector is HFC-134a.
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    EPA and the U.S. Army (Research Development and Engineering 
Command) collaborated on analyzing the probability that HFC-152a or 
CO2 leaks into the passenger compartment would expose 
occupants to refrigerant concentration levels that could lead to driver 
performance decrements, adverse effects on passengers, or flammable 
concentrations of refrigerant. The flow of refrigerant into the 
passenger compartment was modeled using three-dimensional computational 
fluid dynamics (CFD) to predict localized refrigerant concentrations 
over time that would result from a leak.\6\ A typical six passenger 
sedan \7\ was modeled under a broad range of MVAC system operating 
modes (e.g., air conditioning on or off, fan on low or high, 100% 
recirculated air or 100% outside air), including worst case scenarios 
that would result in the maximum possible leak rate. The analysis 
assessed the potential frequency of vehicle occupant and technician 
exposure to elevated levels of CO2 and HFC-152a using 
``fault tree analysis'' (FTA) which EPA has previously used to assess 
frequency and potential consequences of HFC-134a refrigerant releases 
(Jetter et al., 2001). The analysis quantified the potential for 
occupant exposure as a result of a range of leak scenarios and usage 
modes where no risk mitigation systems were engineered into the A/C 
systems, as well as scenarios that included engineering technology to 
reduce exposures. The probability of exposure during servicing was 
assessed for trained technicians and for untrained ``do-it-
yourselfers'' (DIYers) in a variety of work situations.
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    \6\ The U.S. Army CFD model was previously developed for risk 
assessment of other chemicals.
    \7\ Modeling assumed 6 adult passengers in the car.
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    In this rulemaking, CO2 and HFC-152a risks are 
considered in relation to the risks associated with the predominant 
ozone-depleting substance (ODS) refrigerant substitute in MVACs, HFC-
134a. HFC-134a is a non-flammable, low toxicity refrigerant. The

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EPA's SNAP program does not require that new substitutes be found risk-
free to be found acceptable. In reviewing the acceptability of proposed 
substitutes, EPA considers how each substitute can be used within a 
specific application and the resulting risks and uncertainties 
surrounding potential health and environmental effects. The EPA does 
not want to intercede in the market's choice of available substitutes, 
unless a proposed substitute is clearly more harmful to human health 
and the environment than other alternatives.
    CO2 and HFC-152a MVAC systems are not yet commercially 
available. In the absence of empirical data, EPA selected upper bound 
values for the fault tree probability inputs that would tend to lead to 
higher estimates of equipment failure or leak rates (i.e., worst case 
scenarios), and therefore higher probabilities of passenger exposures 
than might typically be encountered, such as using a car with a high 
ratio of refrigerant charge size to passenger compartment volume.

IV. Carbon Dioxide MVAC Systems

A. Occupant Exposure

    Numerous studies indicate that a spectrum of health effects are 
associated with increasing CO2 exposures. These health 
effects range from symptomatic effects to death (EPA, 2005). 
Individuals exposed to CO2 concentrations as low as 4-5% 
over a few minutes reported headache, uncomfortable breathing and 
dizziness (Schulte, 1964; Schneider and Truesdale, 1922; Patterson et 
al., 1955). Significant performance degradation (e.g., reaction time) 
was noted in pilots exposed to 5% CO2 (Wamsley et al., 1975, 
cited in Wong, 1992). Individuals exposed to 6% CO2 for 
periods as short as two minutes had hearing and visual disturbances 
(Gellhorn, 1936), and significant reasoning and performance decrements 
have been observed in healthy young adults after exposures of 5 minutes 
to 7.5% CO2 (Sayers, 1987). Concentrations of 10% 
CO2 and higher can cause loss of consciousness, seizures, or 
even death (Hunter, 1975; Lambertsen, 1971; OSHA, 1989).
    Elevated CO2 concentrations can result from human 
respiration in a sealed space, such as a car, without the introduction 
of fresh air. For example, after 60 minutes in a sub-compact car with 
four adult passengers and the A/C system in recirculation mode, the 
total CO2 concentration is estimated to be approximately 
2.4% (EPA, 2005). In designing their systems and necessary mitigation 
devices, original equipment manufacturers (OEMs) should account for 
potentially elevated background CO2 concentrations that can 
result without a discharge of CO2 into the passenger 
compartment.
1. Upper Limit for Vehicle Occupant Exposure
    In proposing the upper CO2 limit for vehicle occupant 
exposure, EPA relied on guidance from National Institute for 
Occupational Safety and Health (NIOSH) of the Centers for Disease 
Control and Prevention. Based on adverse effects associated with 
overexposure to CO2 ranging from rapid breathing and heart 
palpitations, headache, sweating, shortness of breath and dizziness, to 
convulsions and death, NIOSH has adopted a Recommended Exposure Limit 
(REL) for short-term CO2 exposure of 3% averaged over 15 
minutes. NIOSH's REL for short-term CO2 exposure is the same 
as the American Conference of Governmental Industrial Hygienists 
(ACGIH) short-term exposure limit (STEL) for CO2.
    EPA focused on short-term passenger exposures for three reasons. 
First, occupants experiencing decreased cooling of the A/C system as a 
result of refrigerant leaks may also respond by opening windows or 
increasing fan speed. The introduction of outside air by a vehicle 
occupant would mix with discharged CO2 and dilute a 
potentially hazardous concentration. The second reason is that average 
trip duration is about 30 minutes.\8\ The third reason is that vehicle 
occupants who start to experience abnormal breathing or other 
physiological effects of CO2 exposure will likely react by 
increasing the fan speed or opening windows to increase their comfort 
level by reducing the sense of stuffiness. EPA proposes that direct 
loop refrigerant systems that have the potential for release of 
refrigerant into the occupant compartment or the A/C air distribution 
system, must have safety mitigation necessary to prevent concentrations 
higher than the CO2 STEL (3% averaged over 15 minutes). EPA 
seeks comment on this use condition and also whether a maximum 
CO2 ceiling in the breathing zone should be applied in 
addition to the 3% free space limit averaged over 15 minutes. A 
breathing zone ceiling may provide additional assurance regarding 
vehicle driver alertness. Public comments suggesting a breathing zone 
ceiling should specify the suggested level, justified by literature 
from scientific, safety standard, and other sources published 
worldwide.
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    \8\ Atkinson, 2002.
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2. Potential Occupant Exposure With No Safety Mitigation
    Computational fluid dynamics (CFD) modeling demonstrated where peak 
concentrations of refrigerant could appear in the passenger compartment 
as a result of different leak events, and whether those peaks are 
likely to be above the CO2 STEL. U.S. Army modeling 
conducted as part of the EPA risk analysis indicated that 
CO2 leaks in a stationary or slowly moving vehicle in full 
recirculation mode, without mitigation devices or other safety features 
could result in peak concentrations of about 10% and levels above 6% 
for roughly an hour which are well above the CO2 STEL.
3. Occupant Exposure With Risk Mitigation
    The analyses indicate that direct expansion CO2 systems 
without additional safety features could result in vehicle occupant 
exposures above the CO2 STEL. However, based on the U.S. 
Army CFD modeling, properly engineered safety systems added to 
CO2 systems can reduce the chance of occupant exposure to 
levels above the CO2 STEL, thus making the risks of 
CO2 comparable to HFC-134a. EPA is interested in comment on 
the adequacy of available mitigation systems for CO2 in 
minimizing risks to passengers.
    One possible strategy to limit refrigerant leakage into occupied 
passenger space is to detect the leak and activate a device referred to 
as a ``squib valve'' to vent the CO2 to a location outside 
of the passenger compartment, such as a wheel well or tail pipe. The 
CFD modeling estimated peak concentrations in the passenger compartment 
when a squib valve is used to evacuate the refrigerant charge. The U.S. 
Army CFD modeling conducted to date indicates that when the squib valve 
is activated within 10 seconds after a leak event is detected, the 
maximum concentration remains well below the CO2 STEL. The 
Agency is interested in comment on whether a squib valve activation 
faster than 10 seconds would be needed, or whether any squib valve 
technology is sufficient to protect against possible adverse effects 
associated with very brief (e.g., 5 second) potentially elevated 
exposures (e.g., 5-10% CO2), and the likelihood that 
occupants would encounter such high exposures.
    Another way to reduce CO2 exposure would be to increase 
the amount of outside air that is introduced to the car. CFD modeling 
revealed that when the A/C system uses 100% outside air, as opposed to 
recirculated air, CO2 levels

[[Page 55144]]

remained below the CO2 STEL after a foreseeable worst case 
scenario leak.\9\
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    \9\ Although this would effectively mitigate safety hazards 
there would likely be a large fuel efficiency penalty if this 
strategy were used since the system would not use recirculated air 
at all.
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    Other potential risk mitigation strategies that reduce the 
likelihood of exceeding the CO2 STEL in the free space of 
the passenger compartment include:
     Eliminating the possibility of passenger exposure by 
separating the refrigerant from the passenger compartment with 
secondary loop systems.
     Evaporator isolation valves whose default position is 
closed. Such valves would allow only a fraction of the total charge to 
be released into the passenger compartment in the event of a leak.
     Close-coupled or hermetically sealed systems that would 
both reduce charge size and decrease the possibility of a leak event.
     Automatic increases in the air exchange in the passenger 
compartment upon detection of leaks.
     Automatic venting of refrigerant outside the passenger 
compartment in the air exchange of the passenger compartment upon 
detection of leaks.
    The Agency is interested in comment on whether these risk 
mitigation strategies are technically feasible, considering fuel 
efficiency and overall system performance criteria.

B. Service Technician Exposure

    Risks to service personnel from CO2 systems can result 
from the high pressure of the systems. Carbon dioxide A/C systems are 
high-pressure systems that require service personnel to take safety 
precautions and measures. Injury could occur as a result of the 
potentially high force of an unexpected failure of system components or 
from gas escaping during parts disassembly.
    Risks to service personnel from CO2 systems can also 
come about from overexposure to CO2 in an unexpected system 
release. Because CO2 is heavier than air, the gas will sink 
and could cause high concentrations in low lying areas such as service 
pits. Service technicians should be aware of the potential for 
CO2 build-up in these areas and protect against exposure to 
high concentrations. The Occupational Safety and Health Administration 
(OSHA) Permissible Exposure Limit (PEL) for CO2 is 5,000 
parts per million (ppm) (or 0.5%) over an eight hour time weighted 
average.
    EPA analysis revealed that the risk of potentially hazardous 
exposure to CO2 as a result of working on MVAC systems is 
within the level of risk service technicians currently accept as part 
of their job. Technicians handle high pressure gases such as 
CO2 on a daily basis. However, it is recommended that 
service technicians become knowledgeable about the hazards associated 
with CO2 systems and that additional training be provided.
    ``Do-it-yourself'' repairers (DIYers) working with CO2 
systems face the risks of working with high pressure, including 
potentially high force from an unexpected leak from the system or a 
CO2 tank. Consistent with Society of Automotive Engineers 
(SAE) J639 Standard, CO2 systems must be labeled with a 
nameplate or tag indicating the air conditioning system is under high 
pressure and should only be serviced by qualified personnel. These 
labels combined with unique fittings for CO2 systems are 
expected to help mitigate potential for risk or injury to DIYers.

C. Environmental Information

    Carbon dioxide has an ozone depletion potential (ODP) of zero. The 
original ozone depleting substance in MVACs, CFC-12, has an ODP of 
1.\10\ The predominant MVAC substitute, HFC-134a has an ODP of 
zero.\11\ Carbon dioxide, CFC-12, and HFC-134a are all excluded from 
the definition of volatile organic compound (VOC) under CAA regulations 
(see 40 CFR 51.100(s)) addressing the development of State 
implementation plans (SIPs) to attain and maintain the national ambient 
air quality standards.
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    \10\ World Meteorological Organization (WMO) Science Assessment 
of Ozone Depletion, 2002.
    \11\ WMO Science Assessment of Ozone Depletion, 2002.
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D. Acceptability Determination

    EPA proposes to list CO2 acceptable with the use 
condition that MVAC systems are designed so that occupant exposure to 
concentrations above the CO2 STEL of 3% averaged over 15 
minutes are avoided, even in the event of a leak. We request comment on 
whether a maximum ceiling CO2 level should be applied in the 
driver and passenger breathing zone and the scientific basis for such a 
limit. The addition of the squib valve/directed release system is one 
possible strategy for mitigating risk for CO2 systems. Other 
mitigation strategies may also prove equally or more effective.
    Prominent labeling of CO2 MVAC systems with a warning 
such as ``CAUTION SYSTEM CONTAINS HIGH PRESSURE CARBON DIOXIDE 
(CO2)--TO BE SERVICED ONLY BY QUALIFIED PERSONNEL'' is 
required. Consistent with Society of Automotive Engineers (SAE) J639 
Standard, this label should be mounted in the engine compartment on a 
component that is not normally replaced and where it can be easily 
seen. This label must include CO2 identification information 
and indicate that CO2 is potentially toxic.
    Original equipment manufacturers (OEMs) are required to keep 
records of the tests they perform to ensure that MVAC systems are safe 
and are designed with sufficient safety mitigation devices to ensure 
that occupants are not exposed to levels above the CO2 STEL 
under foreseeable circumstances. Presently, no standard test procedure 
exists to determine that concentrations of concern are not exceeded. 
EPA is working with SAE to develop these test standards and expects 
them to be in place by the time that CO2 MVAC systems are 
deployed in U.S. vehicles. Other use conditions are already established 
in Appendix D to subpart G of 40 CFR part 82 that are applicable to all 
substitute refrigerants in MVAC systems (e.g., unique fittings and 
labels).

V. HFC-152a MVAC Systems

A. Toxicity and Flammability

    The American Industrial Hygienists Association (AIHA) Workplace 
Environmental Exposure Limit (WEEL) (8 hour time weighted average) for 
HFC-152a is 1000 ppm (0.1% v/v), the highest occupational exposure 
limit allowed under standard industrial hygiene practices for any 
industrial chemical. The toxicity profile of HFC-152a is comparable to 
CFC-12 and its most prevalent substitute, HFC-134a. The lowest observed 
adverse effect level for HFC-152a toxicity (15%) is above the level of 
flammability concern, discussed below, so protecting against flammable 
concentrations protects against toxic conditions as well.
    A wide range of concentrations has been reported for HFC-152a 
flammability where the gas poses a risk of ignition and fire (3.7%-20% 
by volume in air) (Wilson, 2002). Different test conditions, impurities 
and the measurement approach can all contribute to the range of 
flammable concentrations of HFC-152a. The lower flammability limit 
(LFL) for HFC-152a has been tested by many laboratories using different 
testing protocols with results ranging from 3.7% to 4.2%. EPA selected 
the lowest reported LFL to assess the potential for passenger exposure 
and predict localized pockets of refrigerant concentrations within the 
passenger compartment. This selection increases confidence that the 
substitute

[[Page 55145]]

is regulated in a manner that is protective of the general population.
    Protecting against flammable concentrations of HFC-152a also 
protects against toxic conditions because the lowest observed adverse 
effect level (LOAEL) of HFC-152a is far above the level of flammability 
concern.
1. Upper Limit of Occupant Exposure
    The lowest reported LFL for HFC-152a is 3.7%, which EPA considers 
to pose a fire hazard to occupants and technicians. To assess the 
potential for passenger exposure and predict localized pockets of 
greater refrigerant concentrations in specific locations within the 
passenger compartment, EPA used 3.7% as the upper limit of occupant 
exposure.
    The upper limit of occupant exposure to HFC-152a protects against 
the possibility of flammability. It is important to note that when 
burned or exposed to high heat, HFC-152a like all fluorocarbons 
including CFC-12 and HFC-134a, forms acid byproducts including 
hydrofluoric acid (HF)--a severe respiratory irritant.\12\ OSHA has set 
a Permissible Exposure Limit (PEL) 8-hour occupational exposure limits 
for HF at 3 ppm which is the upper allowable limit for worker exposure. 
Passenger exposure to HF could only occur as a result of a large leak 
in the presence of an ignition source. EPA's approach in the risk 
screen and in setting use conditions is to prevent any fire risk 
associated with HFC-152a use in MVAC systems, which would also prevent 
any potential passenger exposure to HF.
---------------------------------------------------------------------------

    \12\ These decomposition products have a sharp, acrid odor even 
at concentrations of only a few parts per million.
---------------------------------------------------------------------------

2. Potential Occupant Exposure With No Safety Mitigation
    U.S. Army computational fluid dynamics (CFD) modeling simulated 
various leakage scenarios into the passenger compartment and the 
potential for occupant exposures. As an initial screening tool, 
simplified modeling was conducted by assuming uniform mixing of 
passenger compartment air. This type of modeling does not account for 
the pockets of flammable refrigerant that can occur. The results 
indicate that concentrations of HFC-152a that are roughly one-half the 
lower flammable limit (2%) would be reached in all recirculation modes 
(at various fan speeds and A/C on and off) for a stationary vehicle. 
More complex modeling showed that localized concentrations exceeding 
the LFL would occur with minimal mitigation (see below). Therefore, 
this substitute would pose increased risk compared to HFC-134a in the 
absence of sufficient mitigation technology.
3. Occupant Exposure With Safety Mitigation
    U.S. Army CFD modeling included in the risk analysis indicates that 
occupant exposures could be reduced if risk mitigation technology was 
incorporated that reduced the amount of HFC-152a that entered the 
passenger compartment in the event of a leak.
    A 10-second squib valve activation time in a HFC-152a system 
resulted in estimated localized concentrations greater than 3.7% v/v in 
close proximity to the vent for a total of 14 seconds. In comparison, a 
HFC-152a system with no squib valve resulted in estimated localized 
concentrations greater than 3.7% v/v in close proximity to the vent for 
35 seconds. Given the very small areas and time frames of potential 
exposures involved, EPA believes that 10 seconds is an appropriate 
upper bound for the valve activation time, unless the system design can 
also ensure a lower release rate. EPA is interested in comments on 
whether a squib valve activation faster than 10 seconds is necessary, 
or whether any squib valve technology is sufficient to prevent 
potentially hazardous concentrations (i.e., greater than 3.7% for 15 
seconds).
    We also assessed the introduction of outside air through the A/C 
system to investigate whether this would be useful in hazard 
mitigation. CFD modeling showed that potentially flammable 
concentrations would exist for 5 minutes with the introduction of 50% 
outside air, and for 3 minutes with 100% outside air using the 
simplified modeling. While the introduction of outside air alone does 
not yield acceptable outcomes, introducing some outside air at all 
times in addition to another mitigation strategy may be a viable 
option.
    Other potential risk mitigation strategies that reduce the 
likelihood of exceeding the HFC-152a LFL of 3.7% for more than 15 
seconds may include:
     Eliminating the possibility of HFC-152a in the passenger 
compartment by placing the refrigerant only in the engine compartment 
with secondary loop systems.
     Evaporator isolation valves whose default position is 
closed. Such valves would allow only a fraction of the total charge to 
be released into the passenger compartment in the event of a leak.
     Close-coupled or hermetically sealed systems that would 
both serve to reduce charge size and decrease the possibility of a leak 
event.
     Automatic increases in the air exchange in the passenger 
compartment upon detection of leaks.
     Automatic venting of HFC-152a outside the passenger 
compartment in the air exchange of the passenger compartment upon 
detection of leaks.
    The Agency is interested in comment on whether these risk 
mitigation strategies are technically feasible, considering fuel 
efficiency and overall system performance criteria.

B. Service Technician Exposure

    Fault Tree Analysis (FTA) found that the risk of potentially 
hazardous exposure to HFC-152a is higher for service technicians than 
for occupants driving in vehicles with no safety mitigation technology. 
The AIHA occupational exposure limit for HFC-152a is 1000 ppm (0.1% v/v 
averaged over 8-hours). The risk of exposure while servicing vehicles 
depends not only on the number of vehicles a given service technician 
or shop handles, but also on service technician experience and 
training. With proper mitigation and training, the frequency of these 
exposures can be reduced dramatically. Further, EPA believes, based on 
input from service technicians, the flammability potential of HFC-152a 
is within the level of risk technicians currently accept as part of 
their job. Technicians handle flammables comparable to HFC-152a on a 
daily basis. It is recommended however, that additional training be 
provided to service technicians so that they are knowledgable about the 
different hazards associated with working on HFC-152a systems compared 
to CFC-12 or HFC-134a systems. EPA is currently working with A/C 
service and technical associations to anticipate new systems and to 
modify training, as needed.
    ``Do-it-yourself'' repairers (DIYers) working with HFC-152a systems 
face the risks of working with a slightly flammable substance. 
Consistent with Society of Automotive Engineers (SAE) J639 Standard, 
HFC-152a systems should be labeled with a nameplate or tag indicating 
the air conditioning system is under high pressure and should only be 
serviced by qualified personnel. These labels combined with unique 
fittings for HFC-152a systems are expected to help mitigate potential 
for risk or injury to DIYers.

[[Page 55146]]

C. Environmental Information

    HFC-152a has an ODP of zero.\13\ The original ozone depleting 
substance in MVACs, CFC-12, has an ODP of 1. The predominant MVAC 
substitute, HFC-134a has an ODP of zero.\14\ HFC-152a, CFC-12, and HFC-
134a all are excluded from the definition of VOC under CAA regulations 
(see 40 CFR 51.100(s)) addressing the development of State 
implementation plans (SIPs) to attain and maintain the national ambient 
air quality standards
---------------------------------------------------------------------------

    \13\ WMO Science Assessment of Ozone Depletion, 2002.
    \14\ WMO Science Assessment of Ozone Depletion, 2002.
---------------------------------------------------------------------------

D. Acceptability Determination

    Within the refrigeration and air-conditioning sector, EPA proposes 
to find HFC-152a acceptable with the use condition that MVAC systems 
are designed so that foreseeable leaks into the passenger compartment 
do not result in HFC-152a concentrations at or above the lowest LFL of 
3.7% for more than 15 seconds. EPA seeks comment on whether 15 seconds 
is sufficiently protective. The addition of the squib valve/directed 
release system is one effective strategy for mitigating risk for HFC-
152a systems. Other mitigation strategies may also prove effective.
    Prominent labeling of HFC-152a A/C systems is required with warning 
such as ``CAUTION SYSTEM CONTAINS POTENTIALLY FLAMMABLE HFC-152a 
REFRIGERANT--TO BE SERVICED ONLY BY QUALIFIED PERSONNEL''. Consistent 
with SAE J639 Standard, this label should be mounted in the engine 
compartment on a component that is not normally replaced and where it 
can be easily seen. This label should include refrigerant 
identification information and indicate the refrigerant is potentially 
flammable. HFC-152a systems operate at pressures similar to those of 
HFC-134a systems, with which technicians are familiar; therefore EPA 
has determined that additional labeling to address high pressure is 
unnecessary.
    Original equipment manufacturers (OEMs) are required to keep 
records of the tests they perform to ensure that MVAC systems are safe 
and are designed with sufficient safety mitigation devices to ensure 
that occupants are not exposed to levels of HFC-152a at or above 3.7% 
for more than 15 seconds. Presently, no standard test procedure exists 
to determine that concentrations of concern are not exceeded, but EPA 
is working together with stakeholders and standards organizations to 
develop these test standards. The Agency expects these standards to be 
in place by the time that HFC-152a MVAC systems are deployed in U.S. 
vehicles. Other use conditions already established in Appendix D to 
Subpart G of 40 CFR Part 82 are applicable to all substitute 
refrigerants in MVAC systems (e.g. unique fittings and labels).

VI. Other Use Conditions Applicable to Motor Vehicle Air Conditioning 
Systems

    On October 16, 1996, (61 FR 54029), EPA promulgated a final rule 
that prospectively applied certain conditions on the use of any 
refrigerant used as a substitute for CFC-12 in motor vehicle air 
conditioning systems (Appendix D of Subpart G of 40 CFR part 82). That 
rule provided that EPA would list new refrigerant substitutes in future 
notices of acceptability and all such refrigerants would be subject to 
the use conditions stated in that rule. Therefore, the use of both 
CO2 and HFC-152a in motor vehicle air conditioning systems 
must follow the standard conditions imposed on refrigerant substitutes 
previously listed by SNAP, including:
     Use of unique fittings--identified by SAE standard J639 
and subject to EPA approval;
     Application of a detailed label identifying the 
refrigerant in use and if it is potentially flammable or toxic \15\; 
and
---------------------------------------------------------------------------

    \15\ This proposal specifies the language to be used for this 
label to warn technicians of the risks associated with HFC-152a and 
CO\2\.
---------------------------------------------------------------------------

     Installation of a high-pressure compressor cutoff switch 
on systems equipped with pressure relief devices.
    Because HFC-152a and CO2 retrofits of CFC-12 or HFC-134a 
are prohibited by EPA, this document does not consider the additional 
SNAP requirements for MVAC substitutes approved for use in retrofits.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and 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 EO 12866 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. 
Burden means the total time, effort, or financial resources expended by 
persons to generate, maintain, retain, or disclose or provide 
information to or for a Federal agency. This includes the time needed 
to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    This proposed rule is an Agency determination. It contains no new 
requirements for reporting. The only new recordkeeping requirement 
involves customary business practice. 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 (EPA 
ICR No. 1596.05). This Information Collection Request (ICR) included 
five types of respondent reporting and record keeping activities 
pursuant to SNAP regulations: submission of a SNAP petition, filing a 
SNAP/TSCA Addendum, notification for test marketing activity, record 
keeping for substitutes acceptable subject to use restrictions, and 
record-keeping for small volume uses. This proposed rule requires 
minimal record-keeping of studies done to ensure that MVAC systems 
using either HFC-152a or CO2 meet the requirements set forth 
in this rule. Because it is customary business practice that automotive 
systems manufacturers and automobile manufacturing companies conduct 
and keep on file failure mode and Effect Analysis (FMEA) on any 
potentially hazardous part or system, we believe this requirement will 
not impose an additional paperwork burden.
    An Agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR Part 9 and 48 CFR Chapter 15.

[[Page 55147]]

    Copies of the SNAP ICR document(s) may be obtained from Susan Auby, 
by mail at the Office of Environmental Information, Office of 
Information Collection, Collection Strategies Division; U.S. 
Environmental Protection Agency (2822T); 1200 Pennsylvania Ave., NW., 
Washington, DC 20460, by e-mail at auby.susan@epa.gov, or by calling 
(202) 566-1672.

C. Regulatory Flexibility Act (RFA)

    The 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 
this 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 proposed rule on 
small entities, we certify that this action will not have a significant 
economic impact on a substantial number of small entities. The 
requirements of this proposed rule impact car manufacturers and car air 
conditioning system manufacturers only. These businesses do not qualify 
as small entities. The change in CO2 acceptability to 
include use conditions and the imposition of use conditions for HFC-
152a does not impact the small businesses. The change does not impact 
car manufacturers because production-quality CO2 and HFC-
152a MVAC systems are not manufactured yet. Consequently, no change in 
business practice is required by this proposed rule and will not impose 
any requirements on small entities.
    We continue to be interested in the potential impacts of the 
proposed rule on small entities and welcome comments on issues related 
to such impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if the 
Administrator publishes with the final rule an explanation why that 
alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan. The plan must 
provide for notifying potentially affected small governments, enabling 
officials of affected small governments to have meaningful and timely 
input in the development of EPA regulatory proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements. EPA has determined that this rule does not contain a 
Federal mandate that may result in expenditures of $100 million or more 
for State, local, and tribal governments, in the aggregate, or the 
private sector in any one year. This proposed rule does not affect 
State, local, or tribal governments. The enforceable requirements of 
this proposed rule related to integrating risk mitigation devices and 
documenting the safety of substitute refrigerant MVAC systems affect 
only a small number of manufacturers of car air conditioning systems 
and car manufacturers. This proposal provides additional technical 
options allowing greater flexibility for industry in designing consumer 
products. The impact of this rule on the private sector will be less 
than $100 million per year. Thus, this rule is not subject to the 
requirements of sections 202 and 205 of the UMRA. EPA has determined 
that this rule contains no regulatory requirements that might 
significantly or uniquely affect small governments. This regulation 
applies directly to facilities that use these substances and not to 
governmental entities. The change in acceptability of CO2 
does not impact the private sector because manufacturers are not 
producing systems under the current acceptability regulation. This 
proposed rule does not mandate a switch to these substitutes; 
consequently, there is no direct economic impact on entities from this 
rulemaking.

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that 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.''
    This proposal 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 Executive Order 13132. This regulation applies directly 
to facilities that use these substances and not to governmental 
entities. Thus, Executive Order 13132 does not apply to this rule.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 6, 2000), 
requires EPA to develop an accountable process to ensure ``meaningful 
and timely input by tribal officials in the development of regulatory 
policies that have tribal implications.'' ``Policies that have tribal 
implications'' is defined in the Executive Order to include regulations 
that have ``substantial direct effects on one or more Indian tribes, on 
the relationship between the Federal government and the Indian tribes, 
or on the distribution of power and responsibilities between the 
Federal government and Indian tribes.''

[[Page 55148]]

    This proposed rule does not have tribal implications. It will not 
have substantial direct effects on tribal governments, on the 
relationship between the Federal government and Indian tribes, or on 
the distribution of power and responsibilities between the Federal 
government and Indian tribes, as specified in Executive Order 13175. 
This proposed rule 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, Executive Order 13175 does not apply to 
this proposed rule.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    Executive Order 13045: ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies 
to any rule that: (1) Is determined to be ``economically significant'' 
as defined under Executive Order 12866, and (2) concerns an 
environmental health or safety risk that EPA has reason to believe may 
have a disproportionate effect on children. If the regulatory action 
meets both criteria, the Agency must evaluate the environmental health 
or safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency.
    This proposed rule is not subject to the Executive Order 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. There are no experimental or 
anecdotal data to indicate that children are more sensitive than adults 
to the adverse effects of increased CO2 environments.\16\ 
The exposure limits and acceptability listings in this proposed rule 
apply to car occupants, and in particular car drivers and service 
technicians. These are areas where we expect adults are more likely to 
be present than children, and thus, the agents do not put children at 
risk disproportionately.
---------------------------------------------------------------------------

    \16\ Risk Analysis for Alternative Refrigerant in Motor Vehicle 
Air Conditioning (EPA, 2005).
---------------------------------------------------------------------------

    The public is invited to submit or identify peer-reviewed studies 
and data, of which the agency may not be aware, that assesses the 
potential effects of these alternatives on children.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This proposed rule is not a ``significant energy action'' as 
defined in Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (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 manufacturing and repair of alternative MVAC systems. 
Preliminary information indicates that these new systems may be 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 and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law No. 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. The NTTAA directs EPA 
to provide Congress, through OMB, explanations when the Agency decides 
not to use available and applicable voluntary consensus standards. This 
proposed rule regulates the safety and deployment of new substitutes 
for MVAC systems. EPA is referencing the Society of Automotive 
Engineers (SAE) standard J639, which is currently being revised to 
include requirements for safety and reliability for HFC-152a and 
CO2 systems.

VIII. References

    The documents below are referenced in the preamble. All documents 
are located in the Air Docket at the address listed in section I.B.1 at 
the beginning of this document. Unless specified otherwise, all 
documents are available in Docket ID No. EPA-HQ-OAR-2004-0488 at 
www.regulations.gov.

Atkinson, W. 2002. Consumer U