Final

-- October 10, 2014 1 

## Significant New Alternatives Policy Program Refrigeration and Air Conditioning Sector
Risk Screen on Substitutes in Refrigerated Transport

Substitute: R

- 450 A

This risk screen does not contain Clean Air Act (CAA) Confidential Business Informati on

(CBI) and, therefore, may be disclosed to the public.



### 1. INTRODUCTION Ozone

- depleting substances (ODS) are being phased out of production in response to a series of diplomatic and legislative efforts that have taken place over the past two decade s , including the Montreal Protocol and the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection Agency (EPA), as authorized by Section 612 of the CAAA, administers the Significant New Alternatives Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific end

- uses based on assessment of their health and environmental impacts. EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of potential human health and environmental risks posed by the substitute in specific applications. EPA has already screened a large number of substitutes in many end

- use applications within all of the major ODS

using sectors including : refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented in a seri es of Background Documents that are available in EPA's docket. The purpose of this risk screen is to supplement EPA’s Background Document on the refrigeration and air conditioning sector (EPA 1994) (hereinafter referred to as the Background Document) . This risk screen eval uates the potential use of R

- 450 A as a substitute in the refrigerated transport end

- use, specifically in containers, trailers, and ship holds

. Table 1 presents the composition of the proposed substitute.

Table 1

. Composition of R

- 450A and Potential Impurities
Constituent Chemical Formula CAS Number Concentration (Weight Percent) a 1,1,1,2

- Tetrafluoroethane ( HFC

- 134a ) CF 3 CH 2 F 811

- 97

- 2 42 % trans

- 1,3,3,3,

- Tetrafluoro

- 1

- propene ( HFO

- 1234ze (E)) CHFCHCF 3 29118

- 24

- 9 58 %
Potential ImpuritiesFinal

-- October 10, 2014 2 Section 2 summarizes the results of the risk screen for the proposed substitute blend listed in Table 1 . The remainder of the risk screen is organized into the following sections:

 Section 3 : Atmospheric Assessment

 Section 4 : Volatile Organic Compound Assessment

 Section 5 : Discussion of End

- Use Scenario Modeled

 S ection 6 : Potential Health Effects

 Section 7 : Flammability Assessment

 Section 8 : Asphyxiation Assessment

 Section 9 : End

- Use Exposure Assessment

 Section 10 : Occupational Exposure Assessment

 Section 11 : General Po pulation Exposure Assessment

 Section 12 : References


### 2. SUMMARY OF RESULTS
R

- 450 A is recommended for SNAP approval for the refrigerated transport end

- use, specifically containers, trailers, and ship holds

. E PA's risk screen indicates that the use of the proposed substitute will be less harmful to the atmosphere than the continued use of commonly used refrigerants such as CFC

- 12 , R

- 50 2 , and HCFC

- 22 , as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime

. Neither of the components of R

- 450A are subject to volatile organic compound (VOC) regulations u nder the CAA (40 CFR 51.100(s)) , so environmental impact from the release of these substances is not a concern

. It is expected that the material safety data sh eet ( MSDS ) for R

- 450 A and good manufacturing practices will be adhered to , and appropriate safety and personal protective equipment (PPE) (e.g., protective gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in cas e of leakage or insufficient ventilation) consistent with Occupational Safety and Health Administration ( OSHA ) guidelines will be used during manufacture, servicing, and disposal of refrigerated transport units using R

- 450 A

. In addition, it is expected that leak detectors will be installed inside refrigerated transport containers and container doors will be open during end

- use to prevent significant exposure to R

- 450A in the case of catastrophic leakage. Because refrigerated t ransport units are to be installed in locations with adequate space and/or ventilation (i.e. outdoors) in accordance with EPA recommendations and the equipment maintenance manual s for R

- 450 A in refrigerated transport end

- use , significant toxicity risk to c onsumers is also unlikely. In addition, because R

- 450A is considered to be nonflammable , the proposed substitute is not expected to present a flammability concern. Additional safeguards , including specified refrigerant concentration limits (RCL) of R

- 450A and its components, are also provided by adherence to industry standards including American Society of Heating, Refrigerating and Air

- Conditioning Engineers (ASHRAE) Standards 15, 1 34, 2 and 62. 3


### 3. ATMOSPHERIC ASSESSMENT This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R

450 A in refrigerated transport. The ozone depletion potential ( ODP ) , global warming potential ( GWP ) , and atmospheric lifetime (ALT) of the proposed su bstitute are presented in Table 2

.

1 Safety Standard for Refrigeration Systems ASHRAE Standard 15 establishes safeguards for life, limb, health, and property and prescribes safety requirements. 2 Designation and Safety Classification of Refrigerants ASHRAE Standard 34 establishes a uniform system for assigning reference numbers, safety classifications, and refrige rant concentration limits to refrigerants. Safety classifications based on toxicity and flammability data are included. 3 Ventilation for Acceptable Indoor Air Quality ASHRAE Standard 62 establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects

.Final

-- October 10, 2014 3 The proposed substitute is substantially less harmful to the ozone layer, has lower climate impact, and a shorter a tmospheric lifetime when compared to refrigerants currently used in refrigerated transport, such as CFC

- 12 , R

- 502 , and HCFC

- 22

. In addition, R

- 450 A also has lower climate impact and a shorter atmospheric lifetime than those predicted for other substitutes examined in the Background Document as well as commonly utilized refrigerants HFC

- 134a, R

- 404A , R

- 507A, and R

- 407C . Thus, EP A believes that the use of R

- 450 A would result in substantially less harm to the climate and ozone layer than the continued use of O DS and other commonly used refrigerants

. Table 2 . Atmospheric Impacts of R

- 4 50 A Components Compared to Other Retail Food Re f rigerants Refrigerant Ozone Depleting Potential ( ODP ) a Global Warming Potential ( GWP ) b Atmospheric Lifetime in Years ( ALT ) R

- 450A 0 60 1 NA c Individual Components HFC

- 134a 0 1,430 14 b HFO

- 1234ze (E) 0 1 d 16.4 days d CFC

- 12 0.82 10,900 100 b R

- 502 e 0. 2 4,650 NA f HCFC

- 22 0.13 1,810 12 a HFC

- 134a 0 1,430 14 b R

- 404A g 0 3,922 NA h R

- 507 A i 0 3,985 NA j R

- 407C k 0 1,774 NA l

a WMO 2010 Scientific Assessment Report (2011) b IPCC 4 th Assessment Report (Forster et al. 2007)

c Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 134a is 14 years and the ALT for HFO

- 1234ze(E) is 10 days (IPCC 4 th Assessmen t Report [Forster et al. 2007], Hodnebrog, O. et al. [ 2013 ] ). d Hodnebrog, O. et al. ( 2013 )

e R

- 502 is a blend consisting of HCFC

- 22 (49%) and CFC

- 115 (51%)

. f Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HCFC

- 22 is 12 years and the ALT for CFC

- 115 is 1,700 years (IPCC 4 th Assessment Report [Forster et al. 2007]). g R

- 404A is a blend consisting of HFC

- 143a (52%), HFC

- 125 (44%) and HFC

- 134a (4%). h Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 143a is 52 years, the ALT for HFC

- 125 is 29 years, and t he ALT for HFC

- 134a is 14 years (IPCC 4 th Assessment Report [Forster et al. 2007]). i R

- 507A is a blend consisting of HFC

- 125 (50%) and HFC

- 143a (50%). j Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 1 25 is 29 years and ALT for HFC

- 143a is 52 years (IPCC 4 th Assessment Report [Forster et al. 2007]). k R

- 407C is a blend consisting of HFC

- 32 (29%), HFC

- 125 (25%) and HFC

- 134a (52%). l Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 32 is 4.9 years, the ALT for HFC

- 125 is 29 years, and t he ALT for HFC

- 134a is 14 years (IPCC 4 th Assessment Report [Forster et al. 2007]).


### 4. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS HFC

- 134a and HFO

- 1234ze(E) are not volatile organic compounds (VOCs) according to CAA regulations (40 CFR 51.100(s)) due to their negligible photochemical reactivity

. Therefore, environmental impacts from the relea se of HFC

- 134a and HFO

- 1234ze (E) as VOCs are not a concern.


### 5

. DISCUSSION OF END

- USE SCENARIOS MODELED R

- 450A has been proposed for use in refrigerated transport units. As provided by the submitter, the typical and maximum charge sizes for R

- 450A in containers, trailers, and ship holds are listed in Table 3. Table 3 . Typical and Maximum Charge Sizes for Various R

- 450A End

- Uses and Applications
End
- Use Application Typical Charge Size (kg) Maximum Charge Size

(kg) Refrigerated Transport Containers 4 5 Trailers 6.5 10Final

-- October 10, 2014 4 Ship Holds 100 >500

To evaluate potential end

- use exposures for R

- 450A in refrigerated transport units , this risk screen examines a scenario in which a catastrophic leak of refrigerant occurs while personnel are inside the refrigerated transport container and the doors to the container are closed . A more reasonable worst

- case scenario for this assessment would consider the catastrophic leak of refrigerant occurring while the container doors are open , because EPA expects the refrigerated container door to be open while personnel
are present inside the container at end

- use (e.g., during loading and unloading of refrigerated goods)

. However, the limitations of the box model used for this assessment do not allow c onsideration of this scenario; calculating the concentration of R

- 450A in the container as it exchanges with the warm, outside air through the open door would require more complex computational fluid dynamic s modeling.
Given these limitations, the risk sc reen evaluates a more unlikely scenario, in which it is assumed that the full charge of the refrigerated transport unit is emitted over the course of one minute into the refrigerated container with the door closed

. Although R

- 450A is denser than air, a ver tical concentration gradient is not assumed, because when the full charge is released, the presence of ventilation and the high pressure operating conditions of the refrigerant are expected to disperse the proposed substitute evenly and immediately through out the refrigerated transport container. It was assumed that an individual is present at the start of the leak and remains in the container until the charge is completely released. Furthermore, this risk screen evaluates a refrigerated transport unit wi th a ventilation rate of 25 m 3 /hr, a lower ventilation rate appropriate for less perishable produce (perishable items require a higher ventilation rate up to 60 m 3 /hr) (Brecht et. al 2000). Hence, b ased on suggested ventilation rates for refrigerated transport units for various types of produce, this analysis conservatively assumes a ventilation rate of 25
m 3 /hr. 4 Table 4 details the end

- use modeling assumptions used in Sections 8 , 9, and 10.

4 Ventilation rates range from 0 to 60 m 3 /hr depending on the type of good that is transported (Hamburg Süd 2010).Final

-- October 10, 2014 5 Table 4

. End

- Use Scenario Model Assumptions Parameter Assumption s ( Containers ) Assumption s (Tr ailers ) Assumption s ( Ship Holds) Refrigerated Transport Container Containers Trailers Ship Holds Charge Size ( k g) 4;5 6.5;10 100;>500 Length of Release (minutes) 1 1 1 Container Size (volume

- m 3 ) 66 (2,360 ft 3 ) a 100 (3,530 ft 3 ) b 7,560 ( 267 ,000 ft 3 ) c Room Ventilation ( m 3 /hr ) 25 25 25 Vertical Concentration Gradient No No No

a Specific information was not availabl e regarding the sizes of the refrigerated transport containers

. Thus, a standard 40 ft. (12.2 m) refrigerated container was used for this scenario, with a height of 7. 75 ft (2.4 m ) (TRAC Intermodal, 2013)

. b According to the United Nations Environmental Programme (UNEP), trailers have box volumes of approximately 100 m 3 (UNEP 2010).

c UNEP reported 7,560 m 3 (267,000 ft 3 ) as the average volume of a reefer ship above 100 gross tonnes (10,000 ft 3 ) (UNEP 20 06 ).
EPA recognizes that refrigerated transport units may be placed in a variety of containers with different sizes and ventilation rates. When units are installed in smaller containers , there is a higher risk for asphyxiation or significant exposure

. To address th is variability in container volumes and charge sizes for refrigerated transport units , this risk screen incorp orates threshold analyses in addition to the worst

- case scenario modeling . The threshold analyses are performed in order to determine the container size and charge size r equirements that ensure that th e use of R

- 450 A in refrigerated transport does not pres ent risk to end

- users or servicing technicians

. 

### 6

. POTENTIAL HEALTH EFFECTS To assess potential health risks from exposure to the proposed substitute in refrigerated transport end

- uses , EPA identified the relevant toxicity threshold values for comparison to modeled exposure concentrations for different scenarios. In March 2014, R

- 450A was submitted to ASHRAE’s Standing Standard Project Committee (SSPC) for inclusion in ASHRAE Standard 3 4 under safety group A1 with a refrigeration concentration limit (RCL) of 72,000 ppm. ASHRAE 34 RCLs are intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during refrigerant
use and protect end

- users from the potential dangers of a catastrophic leak from refrigeration unit (ASHRAE 2010b). ASHRAE Standard 15 implements the aforementioned standard, requiring that “the concentration of refrigerant in an enclosed space following a comple te discharge of a high

- probability system shall not exceed the RCL” (ASHRAE 2010a). As such, this risk screen references the proposed RCL for R

- 450 A in addition to the lower flammability limit, hypoxia no observed adverse effect l evel ( NOAEL ) , and exposure limits, as an additional, conservative limit to ensure that significant flammability, asphyxiation, and end

- use exposure risks , respectively, do not occur. For the occupational exposure analysis, potential risks from chronic and acute wor ker exposure were evaluated by comparing exposure concentrations to available occupational exposure limits. Potential risks of chronic worker exposure were evaluated using workplace guidance levels (WGL). Risks from potential short

- term consumer exposures were evaluated by comparing exposure concentrations to emergency guidance levels (EGL). In the absence of an established short

- term exposure limit (STEL), acute exposure guideline level (AEGL), or emergency response planning guideline (ERPG) for R

- 450A , p otential short

term, end

- use exposures were evaluated on a component basis (i.e., HFC

- 134a and HFO

- 1234ze (E) ). Table 5 lists the relevant toxicity limits for R

- 450A and its component s and is followed by Table 6 , which provides an explanation of each toxicity limit

. EPA’s approach for identifying or developing these values is discussed in Chapter 3 of the Background Document.Final

-- October 10, 2014 6 Table 5

. Exposure Limits of R

- 450 A Components
R
- 450 A Component WGL

(Long
- term Exposure) ppm EGL

(Short
- term Exposure) p pm Refrigerant Concentration Limit (RCL) ppm R

- 450A 880 (8

- hour AEL) 2,640 ( 15

- min STEL ) a 72,000 Individual Components
HFC

- 134a 1 ,000 ( 8

- hour WEEL ) 8,000 (10

- min AEGL

- 1) 8,0 00 (30

- min AEGL

- 1) 50,000
HFO

- 1234ze (E) 800 ( 8

- hour WEEL ) 2,400 ( 15

- min STEL ) b NA c NA = Not available

a Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for the blend R

- 450A. A STEL for R

- 450A of 2,640 ppm was developed by EPA based on the 880 ppm AEL value. The STEL was estimated as three to five times the AEL , which is an established method of estimating a short

- term exposure limit by ACGIH . [STEL] = [AEL] x 3 = 880 ppm x 3 ≈ 2,640 ppm b Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFO

- 1234ze (E) . A STEL for HFO

- 1234ze(E) of 2,400 ppm was developed by EPA based on the 800 ppm WE EL value. The STEL was estimated as three to five times the AEL, which is an established method of estimating a short

- term exposure limit by ACGIH . [STEL] = [AEL] x 3 = 800 ppm x 3 ≈ 2,400 ppm

c Alt hough an RCL has not been proposed for HFO

- 1234ze(E), t he recommended ATEL for HFO

- 1234ze(E) is 59,000 ppm (Honeywell 2014a).

Table 6 . Explanation of Exposure Limit

- Related Terminology a Organization Definition OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Health ACGIH American Conference of Governmental Industrial Hygienists AIHA American Industrial Hygiene Association OARS Occupational Alliance for Risk Science Exposure Limit Definition Explanation Short
- Term Exposure RCL Refrigerant Concentration

Limit The RCL for a refrigerant is intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. The RCL for each refrigerant is the lowest of the Acute

- Toxicity Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable Concentration Limit (FCL). Determination assumes full vaporization with no removal by ventilation, dissolution, reaction, or decomposition and complete mixing of refrigerant in the space to which it is released. ATEL Acute Toxicity Exposure Limit The ATEL is t he refrigerant concentration limit intended to r educe the risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34. The ATEL includes consideration of mortality, cardiac sensitization, anesthetic or central nervous system effects and other escape i mpairing effects and permanent injury. The ATEL is s imilar to the Immediately Dangerous to Life or Health (IDLH) concentrations set by NIOSH

. STEL Short

- Term Exposure Limit A 15

- minute time

- weighted average ( TWA ) exposure that should not be exceeded during a workday, even if the 8

- hour TWA is within the TLV

– TWA , set by ACGIH.

AEGL b,c Acute Exposure Guideline

Level 1 AEGL

- 1 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. Acute Exposure Guideline Level 2 AEGL

- 2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or otherFinal

-- October 10, 2014 7 serious, lon g - lasting adverse health effects or an impaired ability to escape. Acute Exp osure Guideline Level 3 AEGL

- 3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life

- threatening health effects or death. Long
- Term Exposure PEL Permissible Exposure Limit This is an 8

- hour time

- weighted average exposure limit set by OSHA. AEL Acceptable Exposure Limit T he maximum 8

- hour time weighted average (TWA) at which a worker can be exposed regularly without adverse effects. WEEL Workplace Environmental

Exposure Level Developed by OARS for to protect healthy workers against acute and chronic health effects, this limit is based on repeated daily exposures over a working lifetime and averaged over an 8

- hour workday. TLV

- TWA Threshold Limit Value

– Time

Weighted Average T he TWA concentration for a conventional 8

- hour workday and a 40

- hour workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect according to ACGIH.

a All information in this table taken from EPA (1994) except where otherwise noted. b EPA (2012)

c A pplicable to emergency exposure periods ran ging from 10 minutes to 8 hours. According to the MSDS, exposure to R

- 450 A may be hazardous if inhalation, skin contact, or eye contact with R

- 450 A occurs. The most likely pathway of exposure is through inhalation. R

- 450 A can cause symptoms of asphyxiation when present in concentrations high enough to significantly lower oxygen concentrations below 19.5 percent by volume, such as headaches, ringing in ears, dizziness, drowsiness, nausea, vomiting, depression of all senses, and also unconsciousness. Under some circumstances of over

exposure (i.e., oxygen levels fall below 6 percen t by volume), death may occur. If R

- 450 A is inhaled, person(s) should be immediately removed and exposed to fresh air. In accordance with the MSDS, EPA further recommends that if breathing is difficult or irregular , person(s) be given oxygen, provided a q ualified operator is present, a nd medical attention be sought. Rescuers should not attempt to retri eve victims of exposure to R

- 450 A without adequate PPE. At a minimum, a self

- contained breathing apparatus (SCBA) should be worn. Exposures of R

- 4 50 A to the skin may cause frostbite. In the case of dermal exposure, the MSDS for R

- 4 50 A recommends that person(s) immediately wash the affected area with water and remove all contaminated clothing; if frostbite occurs, bathe (not rub) the affected area with lukewarm , not hot, water. If water is not available, cover the affecte d area with a clean, soft cloth , and seek medical attentio n immediately. Exposures of R

- 450 A to the eyes could cause eye irritation. In case of ocular exposure, the MSD S for R

- 450 A recommends th at person(s) immediately flush the eyes, including under the eyelids, with copious amounts of water for 15 minutes. EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for this decision. These risks and procedures after exposure are similar for other common refrigerants. The p otential health effects of R

- 450 A can be minimized by following the exposure guidelines and ventilation and PPE recommendation s outlined in the MSDS for R

- 450 A and th is risk screen.Final

-- October 10, 2014 8 

### 7
. FLAMMABILITY ASSESSMENT
R

- 450A has been submitted to the ASHRAE SSPC 34 committee for classification as an A1 refrigerant, and is considered to be nonflammable ( Honeywell 2014 ) . Based on this classification, manu facture, servicing, and use of R

- 450A is not expected to present a flammability risk in refrigerated transport

. 

### 8

. ASPHYXIATION ASSESSMENT Th e risk of asphyxiation for the worst

- case scenario was investigated for R

- 450 A

. In this section, risk of asphyxiation is assessed in three ways: 1) modeling the oxygen concentration under the charge size and container size specified in the worst

- case scenario, 2) performing a threshold analysis of minimum charge size needed to cause a n asphyxiation risk in the room size specified in the worst

- case scenario 3) performing a threshold analysis of the maximum container size needed to cause an asphyxiation risk with the charge size specified in the worst

- case scenario. This analysis does n ot consider ventilation or conditions that are likely to occur that would increase oxygen levels to which individuals would be exposed, such as open doors , which allow air to flow in and out. As specified in Section 5, the worst

- case scenario does not assu me a vertical concentration gradient. If the proposed substitute passes the screening analysis with these restrictive assumptions in place, it can be reasonably assumed that no risks of asphyxiation will be pres ent under real

- world conditions. The results of the asphyxiation assessment are summarized in Table 7 below. Table 7 . Asphyxiation Assessment a Refrigerated Transport Application Scenario Charge Size ( k g) Effective

Container Size (m 3 ) Percent

Oxygen Concentration b Containers Scenario 1a 5 66 (2,360 ft 3 ) 21 Trailers Scenario 1 b 10 100 (3,530 ft 3 ) 21 Ship Holds Scenario 1 c 500 7,560 (267,000 ft 3 ) 21 Minimum Container Size Threshold Analysis 1a: Charge Size 126 66 (2,360 ft 3 )
12 Maximum Container Size Threshold Analysis 1b: Charge Size 14,610 7,560 (267,000 ft 3 ) Minimum Charge Size Threshold Analysis 2a: Container Size 4 2.1 (74 ft 3 ) Maximum Charge Size Threshold Analysis 2b: Container Size 500 261.8 (9,245 ft 3 ) Bold font indicates modeling results.

a Cells highlighted in green are the scenarios in which the charge and room sizes evaluated in this risk screen are acceptable according to the threshold analysis or the scenarios with acceptable oxygen concentrations, given various modeling assumption opti ons. b The typical c oncentration of oxygen in air is considered to be 21 percent (Mackenzie & Mackenzie 1995)

. In order for a risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) must be reduced to 12 percent. 5 Based on the reasonable worst

- case scenario modeling, a release of R

- 450A in refrigerated transport units does not present a significant risk of asphyxiation. This modeling does not take into account any ventilation which is likely to occur, such as open container doors or openings at the bottom of container doors that allow air to flow in and out, as mentioned above, the actual asphyxiation risk to personnel is likely to be even smaller than modeled. For the asphyxiation threshold analyses shown in Error! Reference source not found. , the conditions at which an asphyxiation concern would exist were determined. Within the smallest container size of 66 m 3 ( 2,360 ft 3 ), as shown under Threshold Analysis 1a, the charge size of the R

- 450A refrigeration unit would have to be at least 126 kg for asphyxiation to be a concern, which is more than thirty times greater than the minimum charge size indicated by the submitter (i. e., 4 kg ). Using the largest charge size of 500 kg , as

5 Twelve percent oxygen in air i s the NOAEL for hypoxia (ICF 1997).Final

-- October 10, 2014 9 shown under Threshold Analysis 2 b , the volume of the container would have to be approximately 262 m 3 ( 9,245 ft 3 ) or smaller for asphyxiation to be of concern. Based on the modeling results and thresho ld analysis in Table 7 , EPA does n ot believe that the use of R

450 A in refrigerated transport poses a significant risk of asphyxiation or imp aired coordination to personnel, provided systems are installed in appropriate spaces according to guidelines from the manufacturer and the MSDS for R

- 450A

. 

### 9. END

- USE EXPOSURE ASSESSMENT This section presents estimates of potential end

- user exposures to R

- 450 A and each of its chemical constituents in the event of a catastrophic release from the proposed substitute’s use in refrigerated transport units

. A n end

- use exposure analysis was performed to examine pot ential catastrophic releases of R

- 450 A under th e scenario outlined in Section 5

. This end

- use exposure assessment examines a scenario in which personnel are located inside the refrigerated transport unit containing goods; such scenarios are expected to occur while the container doors are open. When the container door is opened, a stack effect exists from the presence of the denser, cold air coming into contact with the warm, moist air outside. This effect will cause the colder air to flow outside of the container and become replaced by the warm, outside air through infiltration. Therefore, EPA expects that if a release of the proposed substitute occurs while personnel are present inside the refrigerated transport container (e.g., during loading and unloading of refrigerated goods), the container doors would be open , increasing the air exchange rate inside of the unit and also resulting in diffusion of any R

- 450A to flow towards the outside of the container

. To simulate a worst

- case scenario, the catastrophic release of the entire charge of the unit into the refrigerated container was modeled. The estimated exposures are conservative, as the analysis assumes that a catastrophic release occurs while the refrigerated transport cont ainer doors are closed and also does not consider other variables that would reduce the levels to which individuals would be exposed. The analysis
w as undertaken to determine the 15

- minute exposures for R

- 450 A , which were then compared to the standard toxi city limits presented in Table 5 to assess the risk to end

- users. Because HFO

- 1234ze(E) is present in larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table s 8 a and 8b only display exposures for HFO

- 1234ze(E), the component with greater potential concerns

. Modeling results are presented in Table 8 a.

Table 8 a . End

- Use Exposure Assessment for HFO

- 1234ze(E) Component a Refrigerated Transport Containers Scenario Charge Size (kg) Room Size

(m 3 ) 15
- min TWA End
Use Exposure (ppm) Exposure Limit (ppm) b

Short
- term (15
- min) Acute

toxicity Containers Worst

- Case Scenario 1a 4 66 6,500

2,400 59,000

Worst

- Case Scenario 1b 5 8,100
Trailers Worst

- Case Scenario 1c 6.5 100 7,200

Worst

- Case Scenario 1d 10 11,000 Ship Holds Worst

- Case Scenario 1e 100 7,560 1,530

Worst

- Case Scenario 1f 500 4,090 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios in which the charge and container sizes evaluated in this risk screen are acceptable according to the threshold analysis. b See Table 5 for more information Under the worst

- case scenarios described in Section 5 for refrigerated transport systems in containers, trailers, and ship holds, catastrophic releases of the typical and maximum charge sizes of R

- 450A were modeled

. Although most of the exposure estimates for the reasonable worst

- case scenarios exceed the STEL (i.e., 2,400 ppm) (see Table 8 a ), the STEL is a conservatively

- derived exposure limit that isFinal

-- October 10, 2014 10 intended to protect against risk with a wide safety margin for even the most sensitive of populations. All of these exposure estimates are significantly lower than the acute toxicity exposure limit (ATEL) of 59,000 ppm for HFO

- 1234ze(E), which is a refrigerant concentration l imit intended to reduce the risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34. Furthermore, the estimated exposures for R

- 450A in each of these scenarios are also significantly lower than the RCL for R

- 45 0A (i.e., 72,000 ppm). B ecause the modeling was done using a conservative worst

- case scenario where the refrigerated transport container door is closed , and because normally personnel would be exposed in a situation where the door is open with significantly higher ventilation levels, personnel exposure to the proposed substitute at end

- use is not expected to reach the modeled concentrations shown in Table 8a. Therefore, end

- use exposure is not considered to be a significant risk.
A threshold analysis was performed to determine the combinations of charge sizes and container sizes with a 25 m 3 /hr ventilation rate that would avoid end

- use exposures above the STEL for HFO

- 1234ze(E) (i.e., 2,400 ppm). The results from the threshold analyses are used to establish general guidelines for choosing an effective container size and charge size such that the use of R

- 450A in refrigerated transport units does not presen t risk to end

- users or servicing technicians. The se estimated charge and container sizes are fairly conservative as the analysis does not consider open doors and other variables that would reduce the levels to which individuals would be exposed. The result s of the threshold analyses are presented in Table 8b.

Table 8b. End

- Use Exposure Threshold Analysis

– Charge and Container Sizes Refrigerated Transport Container Scenario Charge Size ( k g) Container Size (m 3 ) End
- Use Exposure (ppm) Containers Threshold Analysis 1a: Charge Size 1

. 5 66 (630 ft 3 )

2,400 a Trailers Threshold Analysis 1b: Charge Size 2

. 2 100 (3,000 ft 3 ) Ship Holds Threshold Analysis 1c: Charge Size 1 60 7,560 (267,000 ft 3 ) Containers Threshold Analysis 2a : Container Size 5 2 40 (8,340 ft 3 ) Trailers Threshold Analysis 2b : Container Size 10 4 80 (16,900 ft 3 ) Ship Holds Threshold Analysis 2 c : Container Size 500 24, 200 (835,350 ft 3 ) Bold font indicates modeling results.

a EPA

- derived STEL (see Table 5). Based on these results, for a minimum container volume of 66 m 3 (630 ft 3 ) , end

- use exposure above the STEL would not be a concern as long as the charge size does not exceed 1

. 5 kilo grams (see Threshold Analysis 1 a in Table 8b ) and for the maximum proposed charge sizes in containers, trailers, and ship holds (i.e. 5, 10, and 500 , kilo grams , respectively ) exposure would not be a concern if the refrigeration unit is installed in a container o f effective volume of at least 2 40 m 3 (8,340 ft 3 ) , 4 80 m 3 (16,900 ft 3 ), and 24, 200
m 3 (835,350 ft 3 ), respectively (see Threshold Analyses 2a, 2b , and 2c in Table 8b ). As shown in Table 8 b, these recommended minimum container sizes vary in direct correlation with charge size , and are more conservative than the intended charg e sizes provided by the submitter. However, these modeling results presented in Table 8a and 8b are derived using the STEL (i.e., 2,400 ppm), which is the most conservative short

- term exposure limit for HFO

- 1234ze(E) and reflect conditions that are assumed to be a worst

- case scenario, as described in Section 5

. Infiltration rates through the opening of a refrigerated truck container have been measured to be approximately 2,520 m 3 /hr, which is roughly 100 times the ventilation rates used in the threshold analyses (Bonjour et. al 2011). A s previously discussed, EPA expects the refrigerated container door to be open while personnel are present inside the container at end

- use, increasing the air exchange rate inside of the unit and also encouraging any R

- 450A to flow towards the outside air. Therefore, under a reasonable worst

- case scenario where the refrigerated container doors are open, the exposures shown in the modeling results (see Tables 8a and 8b) are unlikely.Final

-- October 10, 2014 11 Because refrigerated transport units usin g the proposed substitute were modeled using a conservative, worst

- case scenario where the refrigerated transport container door is closed, personnel exposure above the proposed substitute’s STEL of 2,400 ppm is unlikely. However, these potential exceedanc es emphasize the importance associated with proper equipment use, employment of engineering controls to limit releases and/or exposures, and the need for workforce training. To prevent exposure and reduce the risk of acute toxicity hazards during larger re leases in any location where an R

- 450A system is installed, EPA recommends that the proposed RCL for R

- 450A (i.e., 72,000 ppm or 320 g/m 3 ) and the ATEL for the individual components (i.e., 59,000 ppm for HFO

- 1234ze(E) and 50,000 ppm for HFC

- 134a ) are not
e xceeded and that proper leak protection devices are in place. In addition, EPA recommends the installation of refrigerant detection monitors on both ends of the refrigerated container, especially near the refrigeration system unit, and ensure the doors to the refrigerated container are open while personnel are inside. In addition, EPA recommends that warning labels are present in the refrigerated transport container indicating that R

- 450A refrigerant is in use and can cause suffocation, injury, or death. An example of this warning label would read: “WARNING: R

- 450A gas can cause injury or death. Ventilate the area before entering. A high R

- 450A concentration can occur in this area and can cause suffocation.” Training materials and an operations manual descri bing procedures for proper use of the equipment , safety guidelines for handling R

- 450A , and safety training is required for all personnel operating and servicing the refrigerated transport unit

. These procedures and guidelines s hould be acknowledged and followed to mitigate exposure in case of R

- 450A leakage.


### 10. OCCUPATIONAL EXPOSURE ASSESSMENT This section assesses potential exposures to workers during manufacture, charging and servicing, and disposal of R

- 450 A refrigerated transport eq uipment

. To ensure that use of the proposed substitute in refrigerated transport does not pose an unacceptable risk to workers during charging, servicing, and disposal, occupational exposure modeling was performed using a box

- model approach

. For a detailed description of t he methodology used for this screening assessment , the reader is referred to the occupational exposure and hazard analysis described in Chapter 5 of the Background Document

. Estimates of refrigerant release per event for various release scenarios were obtained from the Vintaging Model. 6 To determine the estimated level of occupational exposure for a constituent in a blend, the total anticipated release rate of the refrigerant is multiplied by the weight percent composition of each compound in the blen d; however, only the exposure concentrations for the HFO

- 1234ze(E) component are shown. The release rate per event was multiplied by the number of events esti mated to occur over a workday. T he release per event was conservatively assum ed to range between 0. 6 percent and 8 percent of the equipment charge during charging and servicing , respectively (see Section 10.2) and 20 percent 7 of the equipment charge during disposal (see Section 10. 3). For equipment charging and servicing, the numbe r of events per workday was assumed to equal the maximum number of units anticipated to be serviced in one day (i.e., eight units divided by eight hours per workday for refrigerated transport units in trailers and rail
cars and one unit divided by eight ho urs per workday for refrigerated units in ship holds ). For disposal, i t was conservatively assumed that 10 units are disposed during an 8

- hour work day for containers and trailers equipment and one unit per day for ship hold systems. The modeled exposure concentrations were compared to short

- term occupational exposure limits at charging and servicing and long

- term exposure

6 ICF International maintains the Vintaging Model for EPA in order to simulate the aggregate impacts of the ODS phaseout on the use and emissions of various ODS and their substitutes over a period of several years across 60 different end

- uses. The model tr acks the use and emissions of various compounds for the annual vintages of new equipment that enter service in each end

- use. The vintage of each type of equipment determines such factors as leak rate, charge size, number of units in operation, and th e ini tial ODS substance that the equipment contained. 7 CARB (2013) estimates an end

- of

- life loss rate of 13

- 19% for refrigerated transport systems and DECC (2011) estimates a disposal loss rate of 20

- 30%. A proposed update to EPA’s Vintaging Model recommen ds an end

- of

- life loss rate of 20% based on these estimates and other assumptions found in recent literature.Final

-- October 10, 2014 12 limits at disposal

. Similar to the end

- use exposure assessment, Table s 9 and 11 only present exposures for HFO

- 123 4ze(E), the component with greater potential concerns.

10 .1 Occupational Exposure at Manufacture

HFC

- 134a is obtained by the submitter from other manufacturers and HFO

- 1234ze(E) is manufactured by the submitter in the United States. During manufacture of the components and blending of R

- 450A, the MSDS for both HFC

- 134a and HFO

- 1234ze(E) should be referenced and proper engineering controls and PPE used.

R

- 450A and its components are not expected to pose a risk to workers during manufacture or blending when the engineering controls and PPE recommendations referenced in the MSDS for HFC

- 13 4 a, HFO

1234ze(E), and R

- 450A are followed. Release points/exposure in chemical manufacturing would typically be where temporary lines are connected or disconnected (i.e ., filling of portable cylinders and portable bulk containers). Refrigerant quality control testing may result in release of de minimus quantities of refrigerant, which would typically be to exhaust ducts or fume hoods. Engineering controls should include normal and local ventilation (e.g., chemical hoods) and vapor

- in

- air detection systems for standard manufacturing procedures so workers can avoid physical contact with the refrigerant and to achieve emission control. In general, use of PPE consistent with OSHA guidelines is recommended, such as respiratory protection (including a self

- contained breathing apparatus [SCBA] in case of insufficient ventilation), tightly sealed goggles, and protective gloves (OSHA 1994). In addition, as for other halogenated re frigerants, there is a risk of generation of toxic degradation products such as hydrogen fluoride and hydrogen chloride if HF C

- 134a or HFO

- 1234ze (E) are exposed to high temperatures or fire. Other reaction products such as carbon dioxide might also be pres ent. Containers should be stored in cool, dry conditions (maximum storage temperature should be 40  C) in well

- sealed receptacles and should not be allowed to contact open flames, glowing metal surfaces, or electrical heating elements. EPA believes that whe n proper handling and disposal guidelines are followed in accordance with both good industrial hygiene and manufacturing practices and the MSDS for R

- 450A and its components , there is no significant risk to workers during the manufacture of R

- 450A

. 10

. 2 Oc cupation al Exposure at Charging and Servicing As indicated by the submitter, large refrigeration equipment (e.g., refrigerated transport units in ship holds ) is typically field

- erected and therefore equ ipment is charged in the field. Smaller refrigeration equipment (e.g. refrigeration units in containers and trailers) would occur by the Original Equipment Manufacturer (OEM). For both OEM system manufacture (i.e. charging at OEM location) and field charging (i.e., charging at the end

- u se location), points of release for charging and servicing these leak

- tight systems would be from connection/disconnection of temporary lines for charging and recovery equipment). Charging occurs within an enclosed area equipped with automatic ventilatio n , refrigerant detectors , and alarm systems. The submitter indicated that charging equipment is operated only by trained technicians. Release points during charging would be connection/disconnection of temporary lines from charging equipment. Refrigerant c ontained in temporary lines during charging would be recovered, and breaking of fittings should result in de minimus releases (Honeywell 2014). During servicing, used refrigerant from R

- 450A in refrigerated transport units is pumped into a canister, where it is stored until it is recycled (i.e., filtered and re claimed/sold ). During the transfer to the initial canister, incidental refrigerant releases may occur during connection and disconnection of the recharging hose fittings (Honeywell 2014). Isolation and evacuation of lines or equipment prior to servicing or repair and the use of compatible seals, gaskets, O

- rings , thread sealants, and minimization of threaded joints all contribute to limiting releases. V entilation, leak mo nitors, and alarms also help minimize exposure.Final

-- October 10, 2014 13 Charging and servicing activities for refrigerated transport units are not expected to result in significant worker exposure when certified technicians follow the procedures outlined in the R

- 450A MSDS and maintenance manual, undergo proper training, and wear appropriate PPE (e.g., gloves and safety glasses). Nevertheless, the potential occupational exposure during servicing was analyzed. The maximum 15

- minute time weighted average (TWA) exposure s for each R

- 4 50 A constituent were estimated for the servicing exposure scenario and compared to the ir respective short

- term exposure limits (see Table 9 )
. Because HFO

- 1234ze(E) is present in larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table 9 only presents exposures for HFO

- 1234ze(E), the component with greater potential
concerns. Table 9 . Occupational Risk Assessment at Charging and Servicing for HFO

- 1234ze (E) Component a

Equipment Scenario Charge Size (kg) 15
- minute TWA Occupational

Exposure (ppm) 15
- min Short Term Exposure Limits (ppm) Charging [0.6% release] Servicing

[8% release]
Containers Reasonable Worst

- Case Scenario 1a 4 1 7 220

2,400 c

Reasonable Worst

- Case Scenario 1b 5 2 1 280
Trailers Reasonable Worst

- Case Scenario 1c 6.5 2 7 360

Reasonable Worst

- Case Scenario 1d 10 41 550 Ship Holds b Reasonable Worst

- Case Scenario 1e 100 41 550

Reasonable Worst

- Case Scenario 1f 500 210 2,800 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios that are deemed to be acceptable given various modeling assumption options. b One installation or servicing event per day was modeled for refrigerated transport units in ship holds

c EPA

- derived STEL (see Table 5 ) The anticipated 15

- minute TWA exposures for the HFO

- 1234ze(E) component of R

- 450A are not anticipated to exceed its ST EL (i.e., 2,400 ppm) for all scenarios except the maximum charge size for ship holds in Reasonable Worst

- Case Scenario 1f (see Table 9). In addition, t he estimated exposures were derived using conservative assumptions, and do not take into account the use of ventilation or PPE. These types of systems are typically serviced by trained personnel using proper industrial hygiene techniques and using proper engineering controls (e.g., local ventilation, refrigerant detectors, and alarm systems). Thus, EPA does n ot believe that charging or servicing of refrigerated transport units containing R

- 450A presents a significant concern to workers.

10

. 3 Occupational Exposure at Disposal Disposal of R

- 450A in refrigerated transport units is expected to occur with limited frequency (approximately one disposal event per day) at disposal facilities and with limited duration of exposure to the installed refrigerant. Typically, p otential exposures to the refrigerant during recovery and disposa l are expected to occur during activities related to decommissioning refrigeration systems (e.g., attaching of hoses associated with draining or otherwise discharging of refrigerant from the refrigeration units into cylinders) and would be similar to those during servicing, because similar refrigerant charging and/or recovery equipment would be used (see Section 10.2 and Table 9 for information and modeling results related to exposure during servicing activities). As shown in Table 9 in Section 10.2, expos ures during servicing (and therefore during typical disposal activities) are not anticipated to present a significant concern for workers. To model a worst

- case scenario during disposal, scenarios were modeled in which the portion of refrigerant that is no t recovered during decommissioning of equipment (e.g., due to technical efficiency of recovery equipment) is released during the recovery process in the presence of workers. The implied maximum release rates workers could be exposed to under the reasonable worst

- case disposal scenario are shown in Table 10.Final

-- October 10, 2014 14 Table 10. Assumed Release Rates during Disposal
E nd
- Use Percent Remaining at Disposal Recovery

Efficiency Implied Maximum

Disposal Release Rate Refrigerated Transport Unit 5 0% 60 % 20 % Source: Release rate assumptio ns consistent with CARB (2013) and DECC (2011) estimates. Because HFO

- 1234ze(E) is present in larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table 11 only presents the maximum estimated 8

- hour TWA occupational exposure levels for HFO

- 1234ze(E) , the component with greater potential concerns. Table 11 . Occupational Risk Assessment at Disposal for HFO

- 1234ze(E) Component a

Equipment Scenario Maximum Charge Size (kg) 8
- hour TWA Occupational Exposure (ppm) 8
- Hour Long

Term Exposure Limits (ppm)
Containers Reasonable Worst

- Case Scenario 1a 4 510

800 b

Reasonable Worst

- Case Scenario 1b 5 630
Trailers Reasonable Worst

- Case Scenario 1c 6.5 820

Reasonable Worst

- Case Scenario 1d 10 1,300 Ship Holds Reasonable Worst

- Case Scenario 1e 100 1 , 600

Reasonable Worst

- Case Scenario 1f 500 7,900 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with exposure levels deemed to be acceptable given various modeling assumption o ptions. b 8

- hour WEEL
The results in Table 11 indicate that long

- term (8

- hour) worker exposure concentrations of the HFO

1234ze(E) component of R

- 450A are not likely to exceed its WEEL (i.e. 8 00 ppm) in containers. The reasonable worst

- case disposal modeling for t railers and ship holds indicates worker exposure concentrations could exceed the WEEL for HF O

- 1234ze(E). Although the modeling indicates that the
worse

- case disposal scenario could exceed the WE EL for HFO

- 1234ze(E), the estimated exposures were derived usi ng conservative assumptions (e.g., no mechanical or local exhaust ventilation) , and represent a worst

- case scenario with a low probability of occurrence (e.g., for smaller refrigerated transport units, it is highly unlikely that a worker would be exposed t o the maximum release rate at disposal for every unit decommissioned in a day) . These types of systems are typically disposed of by Section 608

- certified personnel using proper industrial hygiene techniques to maximize recovery efficiency and limit release s. The average recovery efficiency and maximum disposal release rate (see Table 10) are also representative of release rates for currently used refrigerants in refrigerated transport units (e.g., HFC

- 134a), and there are already established standards of pr actice and training requirements that apply to fluorinated refrigerants to reduce exposures (and would therefore extend to R

- 450A systems)

.
I t is also unlikely that workers would be exposed to the unrecoverable portion of refrigerant during the recovery process , and therefore anticipated exposures would be much lower . For example, some of the refrigerant would likely be dissolved in the refrigerant oil (which would be drawn out and separated from the recovered refrigerant) or trapped within deeper parts o f the refrigeration circuit (e.g., the accumulator or receiver) and wouldn’t be released until the system is actually dismantled later on in the disposal process (Oko

- Recherche 2003). Because anticipated occupational exposures could exceed the exposure limit for HFO

- 1234ze(E) for some of the disposal release scenarios (i.e., Reasonable Worst

- Case Scenarios 1c through 1f) for refrigerated transport applications , the recommendations for proper engineering controls and PPE in the MSDS for R

45 0A should be followed. Adequate ventilation should always be established during any use, handling, or storage of R

- 450A

. If recovery and disposal is taking place in an enclosed space without any mechanicalFinal

-- October 10, 2014 15 ventilation, facilities should be cleared of non

- e ssential personnel and technicians should wear a SCBA and other appropriate protective equipment. Engineering controls should include vapor

- in air detection systems and local exhaust ventilation during use of R

- 450A to prevent dispersion throughout the wo rkplace. In addition, an eye wash and safety shower should be near the manufacturing facility and locations where R

- 450A is stored and ready for use. In general, use of PPE is recommended, such as splash goggles, m echanical resistance gloves (e.g., oil

rep ellent or thermal resistance gloves) when handling cylinders and recovery equipment and chemically

resistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). The installation of signage which warns room occu pants to remain standing (as higher concentrations are likely to accumulate near the floor) and not to enter recessed parts of the facility (e.g., maintenance crawl spaces and below grade service areas) and exit the facility immediately should they hear th e refrigerant detector alarm and/or smell the leaked refrigerant would further minimize toxicity risks. EPA believes that if proper handling and disposal guidelines are followed in accordance with good industrial hygiene and manufacturing practices and the MSDS for R

- 450A, there is no significant risk to workers during the manufacturing, installation, servicing, and disposal of R

- 450A in refrigerated transport units

.



### 11

. GENERAL POPULATION EXPOSURE ASSESSMENT
R

- 450 A is not expected to cause a significant risk to human health in the general population when manufactured for use and used as a refrigerant in refrigerated transport units

. The proposed substitute will be manufactured in a closed process and is proposed for use in closed systems ; thus , significant releases are not anticipated. At room temperature, R

- 450 A is a gas and, therefore, releases to ground or surface water are not anticipated, as R

- 450 A is anticipated to dissipate into the atmosphere upon release to outside air (i.e., because n atural ventilation rates would be higher and there is no enclosed space to maintain a high concentration of R

- 4 50 A). Should air releases during manufacturing operations occur, engineering controls should be used (e.g. , carbon absorption scrubbers) to colle ct R

- 450 A and prevent the release of R

- 4 50 A to the atmosphere. EPA believes that by using proper engineering controls and by following disposal and containment recommendations outlined in the proposed substitute’s MSDS, exposure to R

- 4 50 A is not expected t o pose a significant toxicity risk to the general population.Final

-- October 10, 2014 16 

### 12

. REFERENCES ACGIH. 2012. Guide to Occupational Exposure Values. American Conference of Governmental Industrial Hygienists. ANSI/ASHRAE. 2010a. Standard 15: Safety Standard for Refrigeration Systems. American Society of Heating, Refrigerating and Air

- Conditioning Engineers, Inc.
ANSI/ASHRAE. 2010b. Standard 34: Designation and Safety Classification of Refrigerants . American Society of Heating, Refrigerating and Air

- Conditioning Engineers, Inc.
ANSI/ASHRAE. 2013 a . Standard 62: Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigerating and Air

- Conditioning Engineers, Inc. Bonjour, J. D ucoulombier, M., and Sartre, V. 2011. Experimental Investigation of the Infiltration Heat Load During the Opening of a Refrigerated Truck Body. International Institute of Refrigeration: International Congress of Refrigeration. Available online at http://bright

- blue.eu/wp

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392_DucoulombierSartreBonjour_revised_final.pdf

. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007:The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. C ambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Gallagher, Glenn, Tao Zhan, Ying

- Kuang Hsu, et. al. (CARB) 2013. “High

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gas Emissions in California: Comparison of Ambient

- based versus Inventory

- based Em ission Estimates, and Implications of Refined Estimates.” Environ. Sci. Technol., 2014, 48 (2), pp 1084

– 1093. DOI: 10.1021/es403447v. Publication Date (Web): December 13, 2013. Copyright © 2013 American Chemical Society. Available at http://pubs.acs.org/doi/abs/10.1021/es403447v Hodnebrog, O ., Etminan, M., Fuglestvedt, J. S., Marston, G., Myhre, G., Nielsen, C. J., Shine, K. P., Wallington, T. J. 2013. Global Warming Potentials and Radiative Ef ficiencies of Halocarbons and Related Compounds: A Comprehensive Review, Reviews of Geophysics, 51, 300

- 378, doi:10.1002/rog.20013. Honeywell, Inc. 2014. Solstice® N

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- 540) in Retail Food Refrigeration and Vending Machines. Significant New Alternatives Policy Program Submission to the United States Environmental Protection Agency. May 2014. ICF. 1997. Physiological Effects of Alternative Fire Protection Agents

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-- October 10, 2014 17 the Ozone Layer and the Global Climate System. Intergovernmental Panel on climate Change Technology and Economic Assessment Panel. Cambridge University Press, UK. pp 478. Kataoka, O., M. Yoshizawa, & T. Hirakawa 2000. “Allowable Charge Limit of Flammable Refrigerants and Ventilation Requirements.” Daikin Industries. International Refrigeration and Air Conditioning Conference. Paper 506. Available online at: http://docs.lib.purdue.edu/iracc/506

. Mackenzie, F.T. and J.A. Mackenzie. 1995. Our changing planet. Prentice

- Hall. OSHA. 2004. “Safety and Health Topics: Isobutane.” February 2004. Available online at: < http://www.osha.gov/dts/chemicalsampling/data/CH_247840.html>. TRAC Intermodal. 2013. “Intermodal Industry Overview

– History of Containers and Intermodal Industry”. Available online at: < http://www.tracintermodal.com/wp

content/uploads/PDFs/Introduction% 20to%20Intermodal%20Industry%20

- %20TRAC.pdf >. United Nations Environmental Programme. 20 06 . “20 06 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee (RTOC) 20 06 Assessment. Available online at: < http://ozone.unep.org /Assessment_Panels/TEAP/Reports/RTOC/rtoc_assessment_report06.pdf > United Nations Environmental Programme. 2010. “2010 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee (RTOC) 2006 Assessment. Available online at: http://acd

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. WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010 , Global Ozone Research and Monitoring Project

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