55140 Federal Register / Vol. 71, No. 183 / Thursday, September 21, 2006 / Proposed Rules 

the fact or facts and the evidence it 

intends to provide in support of its 

position. The Commission will hold 

hearings on a Postal Service request 

made pursuant to this subpart when it 

determines that there is a genuine issue 

of material fact to be resolved, and that 

a hearing is needed to resolve that issue. 

10. Revise § 3001.174 to read as 

follows: 

§ 3001.174 Rule for decision. 

The Commission will issue a decision 

on the Postal Service’s proposed 

provisional service in accordance with 

the policies of the Postal Reorganization 

Act, but will not recommend 

modification of any feature of the 

proposed service which the Postal 

Service has identified in accordance 

with § 3001.172(a)(3). The purpose of 

this subpart is to allow for consideration 

of proposed provisional services within 

90 days, consistent with the procedural 

due process rights of interested persons. 

§ 3001.181 [Amended] 

11. In § 3001.181, remove paragraph 

(b) and remove the designation for 

paragraph (a). 

[FR Doc. 06–7870 Filed 9–20–06; 8:45 am] 

BILLING CODE 7710–FW–P 

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. 

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) enduse within the refrigeration and airconditioning 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: http:// 

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 email 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 email at thundiyil.karen@epa.gov. 

Notices and rulemakings under the 

SNAP program are available on EPA’s 

Stratospheric Ozone Web site at http:// 

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 

http://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 


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1 59 FR 13044; March 18, 1994. 

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 http:// 

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 


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2The 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). 

3RISA, 2002. 

4Rebinger, 2005. 

5The predominant substitute in the MVAC sector 

is HFC–134a. 

6The U.S. Army CFD model was previously 

developed for risk assessment of other chemicals. 

7Modeling assumed 6 adult passengers in the car. 

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. 

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

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. 

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 threedimensional 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. 

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 nonflammable, low toxicity refrigerant. The 


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8Atkinson, 2002. 

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) shortterm 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. 

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 


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9Although 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. 

10World Meteorological Organization (WMO) 

Science Assessment of Ozone Depletion, 2002. 

11WMO Science Assessment of Ozone Depletion, 

2002. 

remained below the CO2 STEL after a 

foreseeable worst case scenario leak.9

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. 

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 


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12These decomposition products have a sharp, 

acrid odor even at concentrations of only a few 

parts per million. 

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. 

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. 


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13WMO Science Assessment of Ozone Depletion, 

2002. 

14WMO Science Assessment of Ozone Depletion, 

2002. 

15This proposal specifies the language to be used 

for this label to warn technicians of the risks 

associated with HFC–152a and CO2. 

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 

D. Acceptability Determination 

Within the refrigeration and airconditioning 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 

• 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 recordkeeping for small volume uses. This 

proposed rule requires minimal recordkeeping 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. 


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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 email 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 costeffective 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.’’


rmajette on PROD1PC67 with PROPOSALS1
55148 Federal Register / Vol. 71, No. 183 / Thursday, September 21, 2006 / Proposed Rules 

16Risk Analysis for Alternative Refrigerant in 

Motor Vehicle Air Conditioning (EPA, 2005). 

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. 

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 Use of 

A/C Systems. SAE Automotive Alternate 

Refrigerant Systems Symposium 2002. 

Phoenix, Arizona. 

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 R. Rubenstein. 2001. 

Fault Tree Analysis for Exposure to 

Refrigerants Used for Automotive Air 

Conditioning in the United States. Risk 

Analysis. 21(1):157–170. 

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. 

Memo to Acting Administrator, Marianne L. 

Horinko. 2003. EPA’s Authority to Impose 

Mandatory Controls to Address Global 

Climate Change under the Clean Air Act, 

from Robert E. Fabricant. 

National Institute for Occupational Safety 

and Health. 1976. Criteria for Document for 

Carbon Dioxide. NIOSH Publication No. 

76–194. 

National Institute for Occupational Safety 

and Health. 2005. NIOSH Pocket Guide to 

Chemical Hazards. NIOSH Publication No. 

2005–151. 

Occupational Safety and Health 

Administration. 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. 

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. 

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. SafetyStudy for a Prototypical Mobile R744 A/C 

System. VDA Alternate Refrigerant Winter 

Meeting 2002. Saalfelden, Austria 

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. 

Society of Automotive Engineers (SAE). 

2005. Surface Vehicle Standard J639. 

Safety Standards for Motor Vehicle 

Refrigerant Vapor Compression Systems. 

United States Environmental Protection 

Agency (EPA). 1994. SNAP Technical 

Background Document: Risk Screen on the 

Use of Substitutes for Class I OzoneDepleting Substances: Refrigeration and 

Air Conditioning. 

United States Environmental Protection 

Agency (EPA). 2005. Risk Analysis for 

Alternative Refrigerant in Motor Vehicle 

Air Conditioning. 

Wilson, D.P., R. Richard. 2002. 

Determination of Refrigerant Lower 


rmajette on PROD1PC67 with PROPOSALS1
Federal Register / Vol. 71, No. 183 / Thursday, September 21, 2006 / Proposed Rules 55149 

Flammability Limits in Compliance with 

Proposed Addendum p to Standard 34. HI–

02–7–2 (RP–1073). 

Wong, K.L. 1992. Carbon Dioxide. Internal 

Report, Johnson Space Center Toxicology 

Group. National Aeronautics and Space 

Administration: Houston, TX. 1987. 

List of Subjects in 40 CFR Part 82 

Environmental protection, 

Administrative practice and procedure, 

Air pollution control, Reporting and 

recordkeeping requirements. 

Dated: September 14, 2006. 

Stephen L. Johnson, 

Administrator. 

For the reasons set out in the 

preamble, 40 CFR part 82 is proposed to 

be amended as follows: 

PART 82—PROTECTION OF 

STRATOSPHERIC OZONE 

1. The authority citation for part 82 

continues to read as follows: 

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

7671q. 

Subpart G—Significant New 

Alternatives Policy Program 

2. The first table in Subpart G to 

Appendix B of part 82 is amended by 

adding 2 new entries to the end of the 

table 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 Automobile 

Motor Vehicle Air Conditioning (New equipment only).

Carbon Dioxide 

(CO2) as a substitute for CFC– 

12.

Acceptable subject to use conditions.Engineering strategies and/or devices shall be incorporated into the 

system such that foreseeable 

leaks into the free space 1 of the 

passenger compartment do not result in concentrations greater than 

the CO2 short-term exposure limit 

(STEL) of 3% v/v for 15 minutes.

Manufacturers must adhere to all the 

safety requirements listed in the 

Society of Automotive Engineers 

(SAE) Standard J639, including 

unique fittings and a high pressure 

system warning label.

Additional training for service technicians recommended. 

Manufacturers should conduct and 

keep on file Failure Mode and Effect Analysis (FEMA) on the 

MVAC as stated in SAE J1739. 

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

CO2 concentrations potentially 

contributed from normal respiration 

by the maximum number of vehicle occupants. 

CFC–12 Automobile 

Motor Vehicle Air Conditioning (New equipment only).

HFC–152a as a 

substitute for 

CFC–12.

Acceptable subject to use conditions.Engineering strategies and/or devices shall be incorporated into the 

system such that foreseeable 

leaks into the passenger compartment do not result in HFC–152a 

concentrations of 3.7% v/v or 

above in any part of the free 

space 2 inside the passenger compartment for more than 15 seconds.

Manufacturers must adhere to all the 

safety requirements listed in the 

Society of Automotive Engineers 

(SAE) Standard J639, including 

unique fittings and a flammable refrigerant warning label.

Additional training for service technicians recommended. 

Manufacturers should conduct and 

keep on file Failure Mode and Effect Analysis (FMEA) on the 

MVAC as stated in SAE J1739. 

1Free space is defined as the space inside the passenger compartment excluding the space enclosed by the ducting in the HVAC module. 2Free space is defined as the space inside the passenger compartment excluding the space enclosed by the ducting in the HVAC module. 

[FR Doc. 06–7967 Filed 9–20–06; 8:45 am] 

BILLING CODE 6560–50–P 

FEDERAL COMMUNICATIONS 

COMMISSION 

47 CFR Parts 1, 27, and 90 

[WT Docket Nos. 06–169, 96–86; FCC 06–

133] 

Revisions to Upper 700 MHz Guard 

Band Licenses; Development of 

Operational, Technical and Spectrum 

Requirements for Meeting Federal, 

State and Local Public Safety 

Communications Requirements 

Through the Year 2010 

AGENCY: Federal Communications 

Commission. 

ACTION: Notice of proposed rulemaking. 

SUMMARY: In this document, the Federal 

Communications Commission 

(Commission) seeks comment on 

possible changes to its rules governing 

existing and prospective Upper 700 

MHz Guard Bands licensees as well as 

possible revision to its Upper 700 MHz 

band plan in order to promote the most 

efficient and effective use of the 

spectrum. Specifically, the Commission 

requests comment on whether to extend 

the Commission’s Secondary Markets 

spectrum leasing policies to the Guard 

Bands, whether to increase band 

manager flexibility for incumbents and 

prospective licensees; whether to 

eliminate the prohibition on deploying 

cellular architectures in the Guard 


rmajette on PROD1PC67 with PROPOSALS1