Final

-- October 10, 2014 1 

## Significant New Alternatives Policy Program Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Household Refrigerators and Freezers and Water Coolers

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 b y 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 screen s are presented in a series 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 B ackground Document) . This risk screen eval uates the potential use of R

- 450 A as a substitute i n the household refrigerator and freezer end

- use and the drinking water cooler end

- use

. 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 Constituent Chemical Formula CAS Number Concentration (Weight Percent) aFinal

-- October 10, 2014 3 Constituent Chemical Formula CAS Number Concentration (Weight Percent) a

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 Com pound 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 Population Exposure Assessment

 Section 12 : References



### 2. SUMMARY OF RESULTS

R

- 450 A is recommended for SNAP approval for use in household refrigerators and freezers and water coolers

. 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 CFC

- 12, R

- 502, and HCFC

- 22

, as well as other commonly used refrigerants, 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 i s expected that manufacturers and technicians will adhere to the material safety data sheet ( MSDS ) for R

- 450 A and good manufacturing practices

. Additionally, it is expected that the appropriate safety and personal protective equipment (PPE) (e.g., protecti ve gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in case of leakage or insufficient ventilation) consistent with Occupational Safety and Health Administration ( OSHA ) guidelines will be used during manufacture , installation and servicing, and disposal of household refrigerators and freezers and water coolers using R

- 450 A

. Because household refrigerators and freezers and water coolers are to be installed in locations with adequate space and/or ventilation in accordance with EPA recommendations and the equipment maintenance manual s for R

- 450 A in each end

- use , significant asphyxiation or toxicity risk to consumers is also unlikely. In add ition, because R

- 450A is considered to be nonflammable , the proposed substitute is not expected to present a flammability concern. Additional safeguards , includingFinal

-- October 10, 2014 4 specified refrigerant concentration limits (RCL) of R

- 450 A 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 i ntegrity posed by the use of R

450 A in household refrigerators and freezers and water coolers. The ozone depletion potential ( ODP )

, global warming potential ( GWP ) , and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 2

. The proposed substitute is substantially less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime when c ompared to ODS refrigerants currently in these end

- uses 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 a s commonly utilized refrigerant HFC

- 134 a . 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 ODS and other commonly used refrigerants

. Table 2 . Atmospheric Impacts of R

- 4 50 A Components Compared to Other Refrigerants for

Household Refrigerator and Freezer and Water Cooler
Refrigerant Ozone Depleting Potential ( ODP ) a Global Warming Potential ( GWP ) b Atmospheric Lifetime in Years ( ALT ) b R

- 450A 0 60 1 NA c Individual Components HFC

- 134a 0 1,430 14 HFO

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

- 12 0.82 10,900 100 R

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

- 22 0.13 1,810 12 a HFC

- 134a 0 1,430 14

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], H odnebrog, 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]).



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

HFC

- 134a and HFO

- 1234ze (E) are both exempt from the definition of volatile organic compound (VOC) under CAA regulations (40 CFR 51.100(s) ). Therefore, environmental impacts from the release of HFC

134a and HFO

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

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 is establishes a uniform system for assigning reference numbers, safety c lassifications, and refrigerant 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 5 

### 5

. DISCUSSION OF END

- USE SCENAR IOS MODELED

The submission states that both R

- 450A household refrigerators and freezers and water coolers will have a typ ical charge size of 200 grams a nd a maximum charge size of 1,000 grams

. Household refrigerators and freezers and water coolers can be installed in a wide range of locations with varying room volumes (e.g., residential homes, commercial office buildings). To represent a reasonable worst

- case scenario for the household refrigerators and freezers end

- use and water coolers end

- use , it is ass umed that a catastrophic leak of refrigerant occurs while a household refrigerator is installed at the end

- use (i.e., a small kitchen ) for both t he typical and maximum charge size provided by the submitter

. T he analys i s in this risk screen conservatively assume s that the household refrigerator is located in a small residential kitchen with an effective volume of 18 m 3 (640 ft 3 ) (i.e., excluding the space filled by cabinets, other kitchen equipment

, etc.) and a height of 2.4 meters.

Under the reasonable wo rst

- case scenario, the full charge of the unit is assumed to be emitted into the kitchen with 2.3 air change s per hour (ACH) over the course of two time durations: 1) one minute , which represents a catastrophic release of refrigerant due to a puncture or other major damage to the refrigeration system, and 2) fifteen minutes , which represents the accidental release of refrigerant due to a non

catastrophic leak in the system (e.g., valve failure , pinhole leaks ). The one

- minute time duration is most appropria te for flammable refrigerants and presents a less relevant scenario for R

- 450A, which is nonflammable. Therefore, while we evaluate both of these scenarios in this risk screen for consistency purposes, the scenario which analyzes a release of refrigerant o v er a 15

- minute time duration more accurately represent s a reasonable worst

- case scenario for R

- 450A in household refrigerators and freezers and water coolers. A vertical concentration gradient is also assumed since R

- 450A is denser than air ( i.e., the spe cific gravities of both HFC

- 134a and HFO

- 1234ze(E) are greater than 1) and will settle in higher

concen trations closer to the ground. In order to simulate the vertical concentration gradient of refrigerant following release , it is assumed that 95 percent o f the leaked refrigerant mixes evenly into the bottom 0.4
meter (1.3 feet) of the room, and the rest of the refrigerant mixes evenly in the remaining volume (Kataoka 2000 ). Additionally, because the average breat hing zone is above 0.4 meters and mixing is likely to occur upon release of R

- 450A from the unit because the system pressure is higher than the surrounding atmospheric pressure, the absence of the vertical concentration gradient was also evaluated i n the end

- use exposure assessment (Section 9 ). Table 3 details the end

- use modeling assumptions used throughout the risk screen (i.e., in Sections 7
, 8 and 9 ).

Table 3

. End

- Use Scenario Model Assumptions
Parameter Assumption Room Type Household Kitchen S ize (m 3 ) 18 a (640 ft 3 ) V entilation Rate (air changes per hour) 2.3 a Refrigeration Unit Household Refrigerator Charge S ize (g) 200 b ; 1 ,000 c Duration of R elease (minutes) 1 d ; 15 e Vertical Concentration Gradient Yes ; No

a Background Document (EPA 1994)
b Typical charge size for household refrigerators and freezers and water coolers (Honeywell 2014b)

c Maximum charge size for household refrigerators and freezers and water coolers (Honeywell 2014b)
d Represents catastrophic release due to puncture and/or destruction of system

e Represents non

- catastrophic release due to leak in the system (e.g., valve failure , pinhole leak ) EPA recognizes that household refrigerators and freezers and water coolers ma y be placed in a variety of locations with different room sizes and ventilation rates. When units are installed in smaller, enclosed spaces, there is a higher risk for asphyxiation or exposure concerns. To address th is variability in room volumes and charge sizes for installed household refrigerators and freezers and water coolers, this risk screen incorporates threshold analyses in addition to the worst

- case scenario modeling . The thresholdFinal

-- October 10, 2014 6 analyses are performed in order to determine the room siz e and charge size r equirements that ensure that th e use of R

- 450 A in these end

- uses does not present risk to end

- users or servicing technicians

.


### 6

. POTENTIAL HEALTH EFFECTS To assess potential health risks from exposure to the proposed substitute in household refrigerators and freezers and water coolers , 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 Proje ct Committee (SSPC) for inclusion in ASHRAE Standard 34 under safety group A1 with a n 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 complete 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 ( N OAEL ) , 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 worker 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 s ). Risks from potential short

- term consumer exposures were evaluated by comparing exposure concentrations to emergency guidance levels (EGL s ). 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

, potential short

term, end

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

- 134a and HFO

- 1234ze (E) ). Table 4 lists the relevant toxicity limits for R

- 450A and its component s and is followed by Table 5 , 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.

Table 4

. 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) p pm R

- 450A 880 (8

- hour AEL) 2,640 ( 15

- min STEL ) a 72,000 Individual Components

HFC

- 134a 1 ,000 ( 8

- hour WEEL ) b 8,000 (10

- min AEGL

- 1) 8,0 00 (30

- min AEGL

- 1) 50,000

HFO

- 1234ze (E) 800 ( 8

- hour WEEL ) b 2,400 ( 15

- min STEL ) c NA d
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 Honeywell (2014a)

c 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
d Although an RCL has not been proposed for HFO

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

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

-- October 10, 2014 7 Table 5 . 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 decomposi tion 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 TL V

– 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 other serious, long

- 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 Workplac e 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 The 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 accor ding 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.Final

-- October 10, 2014 8 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 that 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. Th e 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 this risk

screen.



### 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 a ) . Based on this classification, manu facture, servicing, and use of R

- 450A is not expected to present a flammability risk in household refrigerators and freezers and water coolers

.


### 8

. ASPHYXIATION ASSESSMENT The risk of asphyxiation for the reasonable 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 room size specified in the worst

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

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

- case scenario. This analysis does not consider ventilation or conditions that are likely to occur that would increase oxygen levels to which individuals would be exposed, such as open doors or windows, fans operating, conditioned airflow (either heated or cooled), or even openings at the bottom of doo rs that allow air to flow in and out. As specified in Section 5 , th e reasonable worst

- case scenario assumes a vertical concentration gradient

. If the proposed substitute passes the screening analysis with these restrictive assumptions in place, it can be r easonably assumed that no risks of asphyxiation will be pres ent under real

- world conditions. The results of the asphyxiation assessment are summarized in Table 6 below

.Final

-- October 10, 2014 9 Table 6 . Asphyxiation Assessment a ,b

Scenario Charge Size (g) Effective Room Size (m 3 ) Percent Oxygen Concentration in Lower 0.4 Meters Reasonable Worst

- Case 1 2 00 18 (640 ft 3 ) 21% Reasonable Worst

- Case 2 1,000 18 (640 ft 3 ) 19 % Threshold Analysis 1: Charge Size 5,640 18 (640 ft 3 ) 12% Threshold Analysis 2 a : Room Size 2 00 0

. 6 4 ( 22.5 ft 3 ) 12% Threshold Analysis 2b: Room Size 1,000 3.19 ( 113 ft 3 ) 12%
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 options.
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. 4 Based on the reasonable worst

- case scenario modeling, a release of R

- 450A from household refrigerators has an insignificant impact on the concentration of oxygen in the air and therefore does not present a significant risk of asphyxiation. This modeling does not take into account any ventilation which is like ly to occur, such as conditioned airflow, open doors, or even openings at the bottom of doors that allow air to flow in and out, as mentioned above; therefore, the actual asphyxiation risk to person(s) is likely to be even smaller than modeled.

For the as phyxiation threshold analyses shown in Table 6, the conditions at which an asphyxiation concern would exist were determined. Within the reasonable worst

- case room size of 18 m 3 (640 ft 3 ), as shown under Threshold Analysis 1, the charge size of the R

- 450A refrigerator would have to be at least 5,640 grams for asphyxiation to be a concern

, which is approximately 5 times the maximum charge size anticipated by the submitter. In Threshold Analyses 2a and 2b, the volume of the room would have to be .64m 3 (22.5 f

t 3 ) and 3.19m 3 (113 ft 3 ) or smaller f or asphyxiation to be of concern for units with 200

- gram and 1,000

- gram charge sizes , respectively

. Based on the worst

- case modeling results and threshold analysis, EPA does not believe that the use of R

450A in househo ld refrigerators and freezers or water coolers poses a significant risk of asphyxiation or impaired coordination to end

- users or servicing technicians , provided systems are installed in appropriate spaces according to guidelines from the manufacturer and t he 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 household refrigerators and freezers and water coolers

. A n end

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

- 450 A under the reasonable worst

- case scenario outlined in Section 5

. For the end

- use exposure assessment scenario, 15

- m in ute TWA exposures for the proposed substitute were calculated using the box model described in the Background Document, which was adapted to estimate concentrations on a minute

- by

- minute basis. Estimates for acute/short

- term end

- use exposures resulting f rom catastrophic leakage of refrigerant from household refrigerators were examined. The analysis w as undertaken to determine the 15

- minute exposures of R

- 450 A , which were then compared to the standard toxicity limits presented in Table 4 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 7 displays only HFO

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

. The estimated TWA value s are fairly

4 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997).Final

-- October 10, 2014 10 conservative as the analysis does not consider opened windows, fans operating, conditioned airflow (either heated or cooled) and other variables that would reduce the levels to which individuals would be exposed.

Table 7 . End

- Use Exposure Ass essment for HFO

- 1234ze (E) Component a

Scenario Charge

Size (g) Room Size

(m 3 ) Vertical

Concentration Gradient Duration

of Release (min) 15

- min TWA End

Use Exposure (ppm) b Reasonable Worst

- Case Scenario 1a 200 18 (640 ft 3 ) Yes 1 5,970 Reasonable Worst

- Case Scenario 1b No 1 994 Reasonable Worst

- Case Scenario 1c Yes 15 3,470 Reasonable Worst

- Case Scenario 2a 1,000 18 (640 ft 3 ) Yes 1 29,800 Reasonable Worst

- Case Scenario 2b No 1 4,970 Reasonable Worst

- Case Scenario 2c Yes 15 17,400 Threshold Analysis 1: Charge Size 80.5 18 (640 ft 3 ) Yes 1 2,400 Threshold Analysis 2a: Room Size 200 44.7 (1,470 ft 3 ) Threshold Analysis 2b: Room Size 1,000 224 (7,340 ft 3 ) Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options.
b 15

- min STEL for HFO

- 1234ze(E) is 2,400 ppm and ATEL for HFO

- 1234ze(E) is 59,000 ppm; s ee Table 4 for more information

.
Under the reasonable worst

- case scenarios described in Section 5 for household refrigerators, catastrophic releases of the typical and maximum charge sizes of R

- 450A (i.e., 200 grams and 1,000 grams, respectively ) were modeled. The modeling scenarios evaluate the presence and absence of a vertical concentratio n gradient as well as two refrigerant release time durations (i.e., 1 minute and 15 minutes). The anticipated 15

- min ute TWA exposures of the HFO

- 1234ze(E) component of R

- 450A do exceed its STEL (i.e., 2,400 ppm) for all scenarios except Reasonable Worst

- Ca se Scenario 1b, which does not assume the presence of a vertical concentration gradient

. Although most of the exposure estimates for the reasonable
worst

- case scenarios exceed the STEL (i.e., 2,400 ppm) (see Table 7 )

, the STEL is a conservatively

derived e xposure limit that is intended to protect against risk with a wide safety margin for even the most sensitive of populations. A ll 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 limit intended to reduce the risks of acute toxicity hazards in normally occupied, en closed 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

- 450A (i.e., 72,000 ppm).

In addition, t hese exposure estimates were derived using fa irly conservative assumptions (e.g., minimum room volume

, low ventilation rate ) that do not necessarily reflec t the actual room attributes where R

- 450 A household refrigerators and freezers and water coolers will be installed

. Specifically, R easonable W orst

C ase S cenarios 1a through 1c model a 200

- gram refrigerator, which represents an average refrigerator size (i.e., 20

– 25 ft 3 capacity) , in a fairly small kitchen size that would likely contain a smaller refrigerator (e.g., 10 ft 3 capacity ). In addition, a 1,000

- gram refrigerator represents a high

- end, commercial

- sized refrigerator

, that is generally installed in large homes (i.e., greater than 5,000 ft 2 or 465 m 2 ) and are therefore unlikely to be installed in a kitchen with an effective vo lume of 18 m 3 (640 ft 3 )

. Furthermore, k itchen spaces are often connected to other rooms through open pathways without doors (e.g., an eat

- in space or a dining area in an open floor plan home )

, which would increase the effective volume of the space in to which a refrigerant would be released , thereby reducing the likelihood that end

- use rs would be exposed to modeled concentrations

. Finally, these exposures represent concentrations of leaked refrigerant in the bottom 0.4 meter (1.3 feet) of the room

, acco unting for 95 percent of the refrigerant charge in this lower portion of the room

. The probability that an individual would be present in this lower portion (e.g., prone or supine on the floor or crawling infant ) in the event of the catastrophic release of refrigerant is low

.Final

-- October 10, 2014 11 To further analyze potential risks of exposure during end

- use, threshold analyses were conducted to determine the room size and charge size r equirements that ensure that th e use of R

- 450A in these end

- uses does not present risk to end

- users or servicing technicians. Based on these results, EPA recommends that for a minimum room volume of 18 m 3 , the charge size does not exceed 80.5 grams (see Threshold Analysis 1in Table 7) , and that for charge sizes of 200 grams and 1,000 grams, the refrigeration unit not be installed in a room of effective volume less than 44.7 m 3 (1,470 ft 3 ) and 224 (7,340 ft 3 ), respectively (see Threshold Analyses 2a and 2b in Table 7)

. To prevent exposure and potential serious side effects during larger releases

, EPA recommends that the proposed RCL for R

- 450A (i.e., 72,000 ppm or 320 g/m 3 ) is not exceeded in any location where an R

450A system is installed, unless proper leak protection devi c es are in place in order to prevent exposures of R

- 450A beyond the reco mmended limits. P roper leak protection devi c es , engineering control requirements

, and adherence to the MSDS will further ensure that exposure limits are maintained below those described in Table 7

.


### 10. OCCUPATIONAL EXPOSURE ASSESSMENT

This section assesses potential exposures to workers during manufacture, installation and servicing, and disposal of R

- 450 A household refrigerators and freezers and water coolers. To ensure that use of the proposed substitute in household refrigeration units does not pose an unacceptable risk to workers during 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. 5 To determine the estimated level of occup ational 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 ar e shown. For the household refrigerator and freezer and water coolers end

- use s , t he release per event was conservatively assumed to be 0.4 percent of the equipment charge during charging and servicing and 6 3 percent of the equipment charge during disposal

. 6 The release rate per event was multiplied by the number of events esti mated to occur over a workday. For equipment charging and servicing , the number of events per workday was conservatively assumed that eight events of servicing a unit by one servicing technician

occur in an 8

- hour work day

. For disposal, i t was conservatively assumed that ten units are disposed of during an 8

- hour work day

. The modeled exposure concentrations were compared to short

- term occupational exposure limits at installation and servicing and long

- term exposure limits at disposal

.

5 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 more than 40 different applicati ons. The model tracks 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 the initial ODS substance that the equipment contained. The service leak rate and disposal release rate assumptions are consi stent with the household refrigerators and freezer end

- use in Vintaging Model version VM IO file_v4.4_7.29.14

. 6 CARB (2013) estimates an end

- of

- life loss rate of 63% for domestic refrigerated appliances. A proposed update to EPA’s Vintaging Model recommends an end

- of

- life loss rate of 63% based on this estimate and other assumptions found in recent literature.Final

-- October 10, 2014 12 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 manufa cture 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 contro ls 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 PP E 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 ot her halogenated refrigerants, 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 present. 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 when 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 Occupation al Exposure at Charging and Servicing As indicated by the submitter, household refrigerators and freezers and water coolers would typically be charged by the Original Equipme nt Manufacturer (OEM). During OEM system manufacture (i.e ., charging at OEM location), po ints of release for charging and servicing these leak

- tight system s would be from connection/disconnection of temporary lines for charging and recovery equipment. During servicing, used refrigerant from R

- 450A household refrigerators and freezers and water coolers is pumped into a canister, where it is stored until it is recycled (i.e., filtered and reused). During the transfer to the initial canister, incidental refrigerant releases may occur during connection and disconnection of the recharging hose fittings (Honeywell 2014 a ). 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. The submitter indicated that servicing equipment is opera ted only by trained technicians. R oom ventilation, leak monitors, and alarms also m inimize exposure.

Installation and servicing activities for household refrigerators and freezers and water coolers 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 and compared to the ir respective short

- term exposure limits (see Table 8 ). T he modeling results indicate that the maximum anticipated occupational exposure concentrations at no point exceed the short

- term exposure limit for either component

.Final

-- October 10, 2014 13 Table 8 . Occupational Risk Assessment at Servicing a
Component 15

- minute TWA Occupational Exposure (ppm) Short Term Exposure Limits (ppm) Charge Size: 200 grams Charge Size: 1,000 grams HFC

- 134a 0.38 1.9 8,000 b HFO

- 1234ze(E) 0.47 2.4 2,400 c 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 10

- minute and 30

- minute AEGL

- 1; see Table 4 for more information.

c EPA

- derived 15

- minute STEL ; see Table 4 for more information.
T he estimated exposures were derived using conservative assumptions, and represent a worst

- case scenario with a low probability of occurrence. These types of systems are typicall y 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 not believe that installation or servicing of household ref

rigerators and freezers and water coolers containing R

- 450A presents a significant concern to workers.

10

. 3 Occupation al Exposure at Disposal Disposal of R

- 450 A household refrigerators and freezers and water coolers is expected to occur with limited frequency (up to approximately ten disposal event s per day) at disposal facilities and with limited duration of exposure to the installed refrigerant. Potential exposures to the refrigerant during recovery and disposal ar e expected to occur during activities related to draining the refrigerant from the refrigeration units into cylinders (e.g., connecting of pipes). Such activities and related exposure is anticipated to occur within 15

- 30 minutes (per event/day). Table 9 di splays the maximum estimated 8

- hour TWA occupational exposure levels for each component of R

- 450A during disposal. Because modeled exposure levels for both the typical and maximum charge sizes are significantly lower than the 8

- hour exposure limits for eac h component, occupational exposure to the proposed substitute during disposal is not considered a toxicity risk . Further, estimated exposures were derived using conservative assumptions (e.g., no ventilation or use of PPE assumed) and represent a worst

- case scenario with a low probability of occurrence. These types of systems are typically disposed of by trained personnel using proper industrial hygiene techniques.

Table 9 . Occupational Risk Assessment at Disposal a

Component 8

- hou r TWA Occupational Exposure (ppm) 8

- Hour Long Term Exposure Limits (ppm) Charge Size: 200 grams Charge Size: 1,000 grams HFC

- 134a 80.7 403 1,000 b HFO

- 1234ze(E) 99.7 499 800 b Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with exposure levels deemed to be acceptable given various modeling assumption options

. b 8

- hour WEEL

Although anticipated occupational exposures are well below the exposure limits for both R

- 450A components for both typical and maximum charge sizes

, the recommendations for proper engineering controls and PPE in the MSDS for R

- 450A should be followed. Adequate ventilation should always be established during any use, handling, or storage of propane . 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, mechanically

- resistance gloves when handlin g cylinders and chemically

- resistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). 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

- 450 A in household refrigerators and freezers and water coolers

.Final

-- October 10, 2014 14 

### 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 household refrigerators and freezers and water coolers

. 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 anticipat ed to dissipate into the atmosphere upon release to outside air (i.e., because natural 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 collect 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 to pose a significant toxicity risk to the general population.Final

-- October 10, 2014 15 

### 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 Engi neers, 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 Qua lity. American Society of Heating, Refrigerating and Air

- Conditioning Engineers, Inc.
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 Dorl and. 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.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Hodnebrog, Ø., Etminan, M., Fuglestvedt, J. S., Marston, G., Myhre, G., Nielsen, C. J., Shine, K. P., Wallington, T. J. 2013. Global Warming Potentials and Radiative Efficiencies of Halocarbons and Related Compounds: A Comprehensive Review, Reviews of Geophysics, 51, 300

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

- 13 (R

- 45 0 A ) in Household Refrigerators and Freezers and Water Coolers

. Significant New Alternatives Policy Program Submission to the United States Environmental Protection Agency. May 2014.
Honeywell, Inc. 2014b. Response to Incompleteness Letter for Solstice® N

- 13 (R

- 45 0A) Significant New Alternatives Policy Program Submission to the United States Environmental Protection Agency. August 11, 2014.
ICF. 1997. Physiological Effects of Alternative Fire Protection Agents

- Hypoxic Atmospheres Conference. Stephanie Skaggs prep ared the proceedings of the conference held May 22, 1997 in New London, CT.

Kataoka, O., M. Yoshizawa, & T. Hirakawa 2000. “Allowable Charge Limit of Flammable Refrigerants and Ventilation Requirements.” Daikin Industries. International Refrigeration an d 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.

U.S. EPA

. 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on the Use of Substitutes for Class I Ozone

- depleting Substances: Refrigeration and Air Conditioning. Stratospheric Protection Division. March, 1994.

U.S. EPA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: http://www.epa.gov/oppt/aegl/pubs/define.htm

.Final

-- October 10, 2014 16 WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010

, Global Ozone Research and Monitoring Project

- Report No. 52, 51 6 pp., Geneva, Switzerland

.