March 29, 2016 – Final 1 

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

Risk Screen on Substitutes in Commercial Ice Machin es

Substitute: Propane (R-290)

This risk screen is restricted to self-contained co mmercial ice makers meeting the requirements of UL 563.

This risk screen does not contain Clean Air Act (CA A) Confidential Business Information (CBI) and, therefore, may be disclosed to the public. Bra ckets [ ] represent redacted CBI content.



### 1. INTRODUCTION Ozone-depleting substances (ODS) are being phased o ut of production in response to a series of diploma tic and legislative efforts that have taken place over the past two decades, including the Montreal Protoc ol 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 unacceptab le substitutes for ODS in specific end-uses based o n assessment of their health and environmental impact s. 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 pose d by the substitute in specific applications. EPA has already screened a large number of substitutes in m any end-uses and applications within all of the maj or ODS-using sectors including: refrigeration and air conditioning; solvent cleaning; foam blowing; aeros ols; fire suppression; adhesives, coatings and inks; and sterilization. The results of these risk screens a re presented in a series of Background Documents that are available in EPA's docket. The purpose of this risk screen is to supplement EP A’s Background Document on the refrigeration and ai r conditioning sector (EPA 1994) (hereinafter referre d to as the Background Document). This risk screen evaluates the potential use of propane (R-290) as a substitute in the commercial ice machines end-use. Table 1 presents the composition of the proposed su bstitute.

Table 1. Composition of Propane and Potential Impu rities

Constituent Chemical Formula CAS Number Concentration (Weight Percent) a Propane (R

- 290) C 3 H 8 74

- 98

- 6 > 99. 7 % Potential Impurities (Maximum Concentration)

Ethane C 6 H 14 74

- 84

- 0 < 0.17% Propylene C 3 H 6 115

- 07

- 1 < 0.03%

n

- Butane C 4 H 10 106

- 97

- 8 < 0.1% Sulfur S 7704

- 34

- 9 < 0.001% Water H 2 O 7732

- 18

- 5 < 0.0012%

Section 2 summarizes the results of the risk screen for the proposed substitute in Table 1. The remai nder of the risk screen is organized into the following sections:

• Section 3: Atmospheric Assessment

• Section 4: Volatile Organic Compound AssessmentMarch 29, 2016 – Final 2 • Section 5: Discussion of End-Use Scenario Modeled

• Section 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 Propane is recommended for SNAP approval for self-c ontained commercial ice machines that comply with Underwriters Laboratory (UL) Standard 563: Ice Make rs. EPA's risk screen indicates that the use of the proposed substitute will be less harmful to the atm osphere than the continued use of ODS and other commonly used refrigerants, as it is less harmful t o the ozone layer, has lower climate impact, and a shorter atmospheric lifetime (ALT). Propane is regulated as a volatile organic compound (VOC) under CAA regulations (40 CFR 51.100(s)). Based on analysis of potential impacts of hydrocarb on refrigerant emissions on ground-level ozone concentrations, VOCs from the use of propane are no t anticipated to result in greater impacts on local air quality in the United States than other available o ptions. It is expected that the manufacturer’s safe ty data sheet (SDS) for propane and good manufacturing prac tices will be adhered to during handling or use of propane. Additionally, it is expected that the appr opriate safety and personal protective equipment (P PE) (e.g., protective gloves, tightly sealed goggles, p rotective work clothing, and suitable respiratory p rotection in case of leakage or insufficient ventilation) con sistent with Occupational Safety and Health Administration (OSHA) guidelines will be used durin g manufacture, installation and servicing, and disposal of commercial ice machines using propane. Because commercial ice machines are to be installed in locations with adequate space and/or ventilation in accordance with EPA recommendations and the equipment maintenance manuals for propane, signific ant flammability, asphyxiation, or toxicity risk to consumers is unlikely. Additional safeguards, including the refrigerant co ncentration limit (RCL) for propane, are provided i n industry standards such as American Society of Heat ing, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standards 15, 1 34, 2 and 62 3 and UL Standard 563: Ice Makers. 4

1 Safety Standard for Refrigeration Systems ASHRAE St andard 15 establishes safeguards for life, limb, he alth, and property and prescribes safety requirements.
2 Designation and Safety Classification of Refrigeran ts ASHRAE Standard 34 is establishes a uniform syst em for assigning reference numbers, safety classifications, and refr igerant concentration limits to refrigerants. Safe ty classifications based on toxicity and flammability data are included.
3 Ventilation for Acceptable Indoor Air Quality ASHRA E Standard 62 establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acce ptable to human occupants and that minimizes advers e health effects.
4 UL 563 Standard for Safety: Ice Makers establishes safety requirements for self-contained automatic ic e makers employing hermetic refrigerant motor-compressors and air- or water-cooled condensers, and designed for connectio n to alternating-current circuits rated not greater than 600 volts (ANSI/UL 2013).March 29, 2016 – Final 3 

### 3. ATMOSPHERIC ASSESSMENT This section presents an assessment of the potentia l risks to atmospheric integrity posed by the use o f propane in commercial ice machines. The ozone deple tion potential (ODP), global warming potential (GWP), and ALT of the proposed substitute are prese nted in Table 2. The proposed substitute is substantially less harmf ul to the ozone layer, has lower climate impact, an d a shorter ALT when compared to refrigerants such as C FC-12, R-502, and HCFC-22. In addition, propane has lower climate impact and a shorter ALT than tho se predicted for other substitutes examined in the Background Document as well as the commonly utilize d refrigerants R-404A and HFC-134a. Thus, EPA believes that the use of propane would result in su bstantially less harm to the climate and ozone laye r than the continued use of ODS and other commonly used re frigerants. Table 2. Atmospheric Impacts of Propane Compared t o Other Refrigerants used in Commercial Ice Machines
Refrigerant Ozone Depleting Potential (ODP) a Global Warming Potential (GWP) b Atmospheric Lifetime in Years (ALT) b Propane 0 b 3.3 0.03 a CFC

- 12 0.82 10,900 100 R

- 502 c 0. 2 4, 65 7 NA d HCFC

- 22 0.13 1,810 12 a R

- 404A e 0 3,922 NA f HFC

- 134a 0 1,430 14 NA – Not applicable

a World Meteorological Organization (WMO) 2010 Scient ific Assessment Report (2011)
b Intergovernmental Panel on Climate Change (IPCC) 4 th Assessment Report (Forster et al. 2007)

c R-502 is a blend consisting of HCFC-22 (49%) and CF C-115 (51%).
d Atmospheric lifetimes are not given for blends, be cause the components separate in the atmosphere. Th e 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]).

e R-404A is a blend consisting of HFC-143a (52%), HFC -125 (44%) and HFC-134a (4%).
f Atmospheric lifetimes are not given for blends, bec ause the components separate in the atmosphere. The ALT for HFC-143a is 52 years, the ALT for HFC-125 is 29 years, and the ALT for HFC-13 4a is 14 years (IPCC 4 th Assessment Report [Forster et al. 2007]).



### 4. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS Propane is regulated as a VOC under CAA regulations (40 CFR 51.100 [s]). Emissions of propane should be controlled according to CAA and other regulation s by adhering to standard industry practices. EPA prepared a separate analysis in 2014 5 and a follow-on analysis in 2016 6 to evaluate the potential impact of the use of hydrocarbon refrigerants on gr ound-level ozone concentrations in the United State s. These analyses estimated refrigerant emissions from refrigeration and air conditioning equipment, whic h were assumed to contain propylene, isobutane, and/o r propane 7 under different scenarios and compared their resulting relative increases in ozone concent rations against the National Ambient Air Quality

5 Assessment of the Potential Impact of Hydrocarbon R efrigerants on Ground Level Ozone Concentrations (February 2014) [EPAHQ-OAR-2013-0748-0003]
6 Follow-on Assessment of the Potential Impact of Hydrocarbon Refrigerants on Ground Level Ozone Conc entrations (March 2016)
7 EPA uses the maximum incremental reactivity (MIR) o f ethane (0.28 g-O 3 /g-substance) as the threshold for determining whet her a compound has negligible reactivity. Propylene (MI R = 11.57), isobutane (MIR = 1.34), and propane (MI R 0.56) are all considered to be reactive compounds and are therefo re subject to VOC regulations.March 29, 2016 – Final 4 Standard (NAAQS) for ozone of 70 ppb. 8 Under the most conservative scenario it was assume d that propylene was used in all refrigeration and air con ditioning equipment. In more realistic scenarios, a ll three hydrocarbons (and/or blends thereof) were ass umed to be used in certain types of refrigeration a nd air conditioning equipment, depending on the propos ed use of each alternative under submissions receiv ed by the SNAP program at the time of the analysis. End-uses in the evaluation included a number of typ es of smaller, self-contained refrigeration (includ ing commercial ice machines) and room air-conditioning units for which SNAP hydrocarbon applications have been received and/or UL Standards covering flammabl e refrigerants exist. The hydrocarbon emissions from these scenarios were estimated based on EPA’s Vintaging Model, and their potential contributions to ozone concentrations were assessed using EPA’s Comm unity Multiscale Air Quality (CMAQ) model. 9 CMAQ modeling was performed for April through the e nd of September, as these months presented the largest releases of hydrocarbon refrigerant as well as weather conditions favorable for ozone formation. The ozone concentrations were estimated for the Atlanta, Houston, and Los Angeles regions, due to their distinctive geographic setting and chr onic high levels of ground-level ozone, and then sc aled for national emission estimates. The results of the CMAQ modeling indicated that und er the most conservative case which assumed that the most reactive hydrocarbon, propylene, was used in all refrigeration and air conditioning equipment
, there could be an incremental maximum increase of t he 8-hour average as high as 7.8 ppb ozone in 2040. By comparison, the most realistic scenario, in whic h a mixture of hydrocarbon refrigerants are used, refrigerant emissions could potentially increase th e maximum 8-hour average ground-level ozone by no more than 2.5 ppb in 2040 in Los Angeles, the city with the greatest ozone problem. This upper bound level of increase for the realisti c scenario is not likely, as most ozone nonattainme nt areas are not VOC-limited (i.e., the formation of o zone in these areas is not limited by VOC emissions , but by other compounds such as nitrogen oxides [NO x ]). In addition, the analysis assumed no use of VOC

exempt refrigerants which will also likely be used in refrigeration and air conditioning end-uses alon g with hydrocarbon refrigerants. Based on the results of t his analysis, VOC emissions from the use of propane in commercial ice machines are not anticipated to cont ribute significantly to ground level ozone concentrations in the United States.



### 5. DISCUSSION OF END-USE SCENARIOS MODELED Propane has been proposed for the commercial ice ma chine end-use. The modeled end-use scenario assumes a charge size of 150 grams for commercial i ce machines, as indicated by the submitter. The modeled charge size is also consistent with UL Stan dard 563: Ice Makers, which limits the charge size of ice machine refrigeration equipment for ASHRAE clas sified A3 refrigerants to 150 grams (UL 2015).
Commercial ice machines can be installed in a wide range of locations with varying room volumes (e.g., hotels, bars, and restaurants). To represent the re asonable worst-case scenario for commercial ice machines, it is assumed that a catastrophic leak of refrigerant occurs while an ice machine is install ed at end-use (i.e., restaurant kitchen). Based on the ro om sizes provided by the submitter, the analysis in this risk screen assumes that the ice machine is located in a restaurant kitchen with a height of 2.4 meter s (7.8

8 On October 1, 2015, EPA strengthened the NAAQS for ground-level ozone to 70 ppb from 75 ppb, based on scientific evidence about ozone’s effects on public health and welfare (EPA 2015). 9 VM version VM_IO file_v4.4_10.13.14 and CMAQ model version 5.0.2 were used in this analysis.March 29, 2016 – Final 5 feet), a minimum effective volume of 22 m 3 (780 ft 3 ), or a typical effective volume of 120 m 3 (4,240 ft 3 ) (i.e., excluding the space filled by the ice machin e, shelving, other kitchen equipment, etc.). Under this reasonable worst-case scenario, the full charge of the unit is assumed to be emitted over t he course of one minute into the restaurant kitchen wi th 20 air changes per hour (ACH). 10 A vertical concentration gradient is also assumed in the worst -case scenario since propane is denser than air (sp ecific gravity of propane relative to air is 1.52 [air = 1 ]) and will settle in higher concentrations closer to the ground. In order to simulate the vertical concentra tion gradient of refrigerant following release, it is assumed that 95 percent of the leaked refrigerant m ixes evenly into the bottom 0.4 meters (1.3 feet) o f the room, and the rest of the refrigerant mixes evenly in the remaining volume (Kataoka 2000). Table 3 det ails the end-use modeling assumptions used throughout th e risk screen (i.e., in Sections 7, 8 and 9). Table 3. End-Use Scenario Model Assumptions Parameter Assumptions Room Restaurant Kitchen Charge Size (g) 150 a Length of Release (minutes) 1 Room Size (volume

- m 3 ) 22 (7 8 0 ft 3 ); 120 (4,240 ft 3 ) b Room Ventilation (air changes per hour) 20 c Vertical Concentration Gradient Yes

a UL 563 maximum charge size for ice makers using Cla ss A3 refrigerants.
b Manitowoc (2015)

c The typical ventilation rate for a commercial kitch en is 20 to 40 air changes per hour (McMullan 2014)

. EPA recognizes that commercial ice machines may be placed in a variety of locations with different roo m sizes and ventilation rates. There may also be inst ances in which the consumer chooses to place an ice machine and other pieces of equipment (e.g., a vend ing machine) within an enclosed space (thus further limiting the effective volume of the space), or a s ingle ice machine in a very small enclosed space. W hen units are installed in smaller, enclosed spaces, th ere is a higher risk for asphyxiation or exposure c oncerns. To address this variability in room volumes and cha rge sizes for installed ice machines, this risk scr een incorporates threshold analyses in addition to the worst-case scenario modeling. The threshold analyse s are performed in order to determine the room size and c harge size requirements that ensure that the use of propane in commercial ice machines does not present risk to end-users or servicing technicians.



### 6. POTENTIAL HEALTH EFFECTS To assess potential health risks from exposure to t he proposed substitute in commercial ice machines, EPA identified the relevant toxicity threshold values f or comparison to modeled exposure concentrations fo r different scenarios. According to ASHRAE Standard 3 4, propane is listed under safety group A3 with a RCL of 5,300 ppm (ASHRAE 2013a). ASHRAE 34 RCLs are intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during refriger ant use and protect end-users from the potential danger s of a catastrophic leak from a refrigeration unit (ASHRAE 2013a). ASHRAE Standard 15 implements the a forementioned standard, requiring that “the concentration of refrigerant in an enclosed space f ollowing a complete discharge of a high-probability system shall not exceed the RCL” (ASHRAE 2013b). As such, this risk screen references the RCL for propane in addition to the lower flammability limit (LFL), hypoxia no observed adverse effect level

10 The air exchange rate for a commercial kitchen is d erived from the suggested sufficient ventilation in commercial kitchens of 20 to 40 air changes per hour (McMullan 2014).March 29, 2016 – Final 6 (NOAEL) and exposure limits, as an additional, cons ervative limit to ensure that significant flammabil ity, asphyxiation, and end-use exposure risks, respectiv ely, do not occur. For the occupational exposure analysis, potential r isks from chronic and acute worker exposure were evaluated by comparing exposure concentrations with available occupational exposure limits. Potential risks of chronic worker exposure were evaluated usi ng workplace guidance levels (WGL). Risks from potential short-term consumer exposures were evalua ted 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), potential short-term, end-use exposures were evaluated. Table 4 lists the relevant toxicity limits and RCL of pr opane and is followed by Table 5, which provides an expla nation 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 Propane

Component WG L

(Long-term Exposure) ppm EGL (Short-term Exposure) Ppm Refrigerant Concentration Limit (RCL) ppm Propane 1,000 a

(OSHA PEL/NIOSH REL) 10,000 b,c (10

- min AEGL

- 1) 6,900 c (30-min AEGL-1) 5,300 d Potential Impurities
Ethane 1,000 e (ACGIH TLV) 3,000 f (30

- min ACGIH Excursion Limit) 2,900 g (15-min TEEL-1) 7,000 d Propylene 500 e (ACGIH TLV) 1,500 f (30-min ACGIH Excursion Limit) 1,000 d n-Butane 1,000 e (ACGIH TLV) 6,900 h (30-min AEGL-1) 4,000 d An explanation of each exposure limit and exposure- limit related terminology is described in Table 5.

a OSHA PEL available at: http://www.cdc.gov/Niosh/np g/npgd0524.html
b An IDLH of 2,100 ppm has been established for propa ne. However, NIOSH (1996) states that "[b]ased on acute inhalation toxicity data in humans (ACGIH 1991; Braker 1980), a value much grea ter than 10,000 ppm would have been appropriate. Ho wever, the revised IDLH for propane is 2,100 ppm based strictly on safety consi derations (i.e., being 10% of the lower explosive l imit of 2.1%)." Therefore, as this IDLH value is based on flammability concerns and not tox icity concerns, it is not used in the evaluation of toxicity risks in this risk screen.

c AEGL-1 available at: http://www.epa.gov/opptintr/a egl/pubs/results96.htm
d ASHRAE (2010b)

e ACGIH TLV for aliphatic hydrocarbon gases: alkane (C 1 - C 4 ) is 1,000 ppm TWA (ACGIH 2012)
f Calculated as three times the TLV-TWA (ACGIH 2004).

g Department of Energy (DOE) (2008)
h AEGL-1 available at: http://www.epa.gov/oppt/aegl/p ubs/rest102.htm

Table 5. Explanation of Exposure Limit-Related Term inology a Organization Definition OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Heal th ACGIH American Conference of Governmental Industrial Hygi enists 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 (OD L), and Flammable Concentration Limit (FCL). Determination assumes fu ll vaporization withMarch 29, 2016 – Final 7 no removal by ventilation, dissolution, reaction, o r deco mposition and complete mixing of refrigerant in the space to whic h it is released. STEL Short

- Term Exposure Limit A 15

- minute TWA exposure that should not be exceeded dur ing a workday, even if the 8-hour TWA is within the TLV–T WA, set by ACGIH.

AEGL b,c Acute Exposure Guideline

Level 1 AEGL

- 1 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that the gene ral population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effe cts. However, the effects are not disabling and are transient and rev ersible upon cessation of exposure. Acute Exposure Guideline Level 2 AEGL

- 2 is the airborne concentration (expressed as ppm o r mg/m 3 ) of a substance above which it is predicted that the gene ral 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 o r mg/m 3 ) of a substance above which it is predicted that the gene ral population, including susceptible individuals, could experience life-threatening health effects or death.

TEEL d Temporary Emergency

Exposure Limit 1 TEEL

- 1 is the maximum concentration in air below which i t is believed nearly all individuals could be exposed without exp eriencing other than mild transient adverse health effects or perceiving a clearly defined, objectionable odor. Temporary Emergency Exposure Limit 2 TEEL

- 2 is the maximum concentration in air below which i t is believed nearly all individuals could be exposed without exp eriencing or developing irreversible or other serious health eff ects or symptoms that could impair their abilities to take protective act ion. Temporary Emergency Exposure Limit 3 TEEL

- 3 is the maximum concentration in air below which i t is believed nearly all individuals could be exposed without exp eriencing or developing life-threatening health effects. Long

- Term Exposure PEL Permissible Exposure Limit This is an 8

- hour TWA exposure limit set by OSHA. REL e Recommended Exposure

Limit This is an 8

- hour TWA recommended by NIOSH.

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 li fetime without adverse effect according to ACGIH.

a All information in this table is taken from EPA (19 94) except where otherwise noted.
b EPA (2012)

c Applicable to emergency exposure periods ranging fr om 10 minutes to 8 hours.
d DOE (2008)

e NIOSH (2015)
According to the SDS, exposure to propane may be ha zardous if inhalation, skin contact, or eye contact with the proposed substitute occurs. The most likel y pathway of exposure is through inhalation. Propan e 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 sen ses, and also unconsciousness. Under some circumstances of over-exposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. In addition, at high concentrations, propane can act a s a narcotic and cause central nervous system depression, including dizziness, drowsiness, and he adaches.March 29, 2016 – Final 8 If propane is inhaled, person(s) should be immediat ely removed from the contaminated space and exposed to fresh air. In accordance with the SDS, EPA furth er recommends that if breathing is difficult or irr egular, person(s) should be given oxygen, provided a qualif ied operator is present, and medical attention be sought. Exposures of propane to the skin may cause frostbite. In the case of dermal exposure, the SDS for propane 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 affected area with a clean, soft cloth, and seek medical attentio n immediately. Exposures of propane to the eyes could cause eye irritation. In case of ocular exposure, the SDS for propane recommends that person(s) immediate ly flush the eyes, including under the eyelids, wit h copious amounts of water for 15 minutes. EPA’s review of the human health impacts of this pr oposed substitute is contained in the public docket for this decision. The potential health effects of propane can be mini mized by following the exposure guidelines and ventilation and PPE recommendations outlined in the SDS for propane and this risk scree n.



### 7. FLAMMABILITY ASSESSMENT ASHRAE Standard 34 classifies propane as a Class A3 refrigerant. Propane is flammable when its concentration in air is in the range of 2.1 percent to 9.5 percent by volume (21,000 ppm to 95,000 ppm ). In the presence of an ignition source (e.g., static electricity or a cigarette), an explosion or a fir e could occur if the concentration of propane were to excee d the LFL of 21,000 ppm. The remainder of this sect ion addresses flammability risks and summarizes the rec ommended measures to ensure safe handling and use of the refrigerant during manufacture, servicing, a nd end-use. 7.1 Flammability Risks at Equipment Manufacture Release of or exposure to propane may be possible a t the charging and sealing steps on the production line at the manufacturing site. It is therefore importan t that all relevant standards be followed during th e manufacture of ice machine refrigeration units. If the manufacture of commercial ice machines charged with propane occurs in the United States, EPA recom mends that engineering controls should include normal and local ventilation (e.g., chemical hoods) for standard manufacturing procedures so workers c an avoid physical contact with the refrigerant and to limit emissions. In general, use of appropriate PPE consistent with OSHA guidelines is recommended, suc h as splash goggles, mechanically-resistant gloves when handling cylinders, chemically-resistant glove s (e.g., butyl rubber, chlorinated polyethylene, or neoprene) when handling the gas mixture, and protec tive clothing. All propane storage and transport equipment should be installed with safety devices that minimize the likelihood of catastrophic releases. For example, t he National Fire Protection Association (NFPA) 58 Liquefied Petroleum Gas Code (NFPA 2007) for liquef ied propane requires the use of overfill protection devices (OPD) on cylinders to minimize the likeliho od of leaks. The NPFA 58 Code also contains propane storage and transportation requirements/guidelines. It is expected that refrigerants be properly store d and caution used within manufacturing facilities to min imize explosion risk and that workers adhere to the requirements set by OSHA under 29 CFR 1910. OSHA re quirements include proper ventilation and storage practices within manufacturing facilities t o prevent fire and explosion. Good manufacturing practices should be adhered to during the manufactu re of equipment containing propane, e.g., using pro per ventilation. 7.2 Flammability Risk at Servicing and End-Use The risk of flammability during servicing and end-u se for the reasonable worst-case scenario (see Sect ion 5) was investigated for propane. Both servicing and end-use of propane ice machines are expected to ta ke place in the same space (i.e., the installation and use location). In order to determine the potentialMarch 29, 2016 – Final 9 flammability risks during servicing or end-use in c ase of a catastrophic release of refrigerant, model ed concentrations of propane immediately following the release of refrigerant were compared with the LFL for propane. The results of the flammability assessment are pres ented in Table 6.
Table 6 . Flammability Assessment a

Scenario Charge Size (g) Effective Room Size (m 3 ) Vertical

Concentration Gradient Maximum

Instantaneous Concentration (ppm) b,c Reasonable Worst-Case Scenario 1 150 22 (780 ft 3 ) d Yes 21,430 Reasonable Worst-Case Scenario 2 No 3,570 Reasonable Worst-Case Scenario 3 150 120 (4,240 ft 3 ) Yes 3,860 Threshold Analysis 1: Charge Size 147 22 (780 ft 3 ) d Yes 21,000 Threshold Analysis 2: Charge Size 820 120 (4,240 ft 3 ) Yes 21,000 Threshold Analysis 3: Room Size 150 ~22 (780 ft 3 ) d Yes 21,000
Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with a cceptable exposure levels given various modeling as sumption options.
b LFL of propane is 21,000 ppm.

c Values provided in this column refer to the concent ration in the lower 0.4 meters of the room, which p resents the most conservative risk as 95 percent of the leaked refrigerant is pre sent in this space.
d Room sizes for Reasonable Worst-Case Scenarios 1, 2 and Threshold Analyses 1, 3 differ by less than 1 m 3 but appear to be equal due to independent rounding. As presented in Table 6, the maximum instantaneous concentration in the lower 0.4 meters of the room does not exceed the LFL for propane (i.e., 21,000 p pm) in all reasonable worst-case scenarios, excludi ng Reasonable Worst-Case Scenario 1. Although Reasonab le Worst-Case Scenario 1 exceeds the LFL for propane, this exceedance is by approximately 2 perc ent, which is a small enough margin to reconsider t he conservativeness of the assumptions used in the ana lysis. [ ]. Furthermore, commercial kitchen spaces are often connected to other rooms (e.g., an eat-in spa ce, hallway) through open pathways or swinging door s, which would also increase the effective volume of t he space into which a refrigerant would be released
, thereby reducing the likelihood that the instantane ous concentration of propane would exceed the LFL. As a result, release of a 150-gram unit does not prese nt a significant flammability risk in the reasonabl e worstcase scenario for propane in commercial ice machine s. The conditions at which a flammability concern woul d exist (i.e., when the maximum instantaneous concentration in the lower 0.4 meters of the room e quals the LFL for propane) were also determined.

• As shown under Threshold Analysis 1, a flammability concern could occur if the charge size of the commercial propane ice machine unit in a 22 m 3 (780 ft 3 ) room is 147 grams or more, which is slightly smaller than the maximum charge size allow ed by UL 563 (i.e., 150 grams).

• As shown under Threshold Analysis 2, a flammability concern could occur if the charge size of the commercial propane ice machine unit in a 120 m 3 (4,240 ft 3 ) room is 820 grams or more, which is approximately five times the maximum charge size al lowed by UL 563 (i.e., 150 grams).

• Using the charge size of 150 grams for commercial i ce machines, as shown under Threshold Analysis 3, the volume of the room would have to be approximately ~22 m 3 (780 ft 3 ), or slightly larger than the minimum modeled room size provided by the submitter for flammability to be of

concern. According to the results of this flammability analy sis, the risk of fire is minimal if a commercial ic e machine is installed in a room with volumes in acco rdance with standards and regulations and if it mee ts the requirements of UL 563, including a charge size of 150 grams. As restaurant kitchens can be smalle rMarch 29, 2016 – Final 10 than those modeled in this assessment and because persons or equipment in the room may re duce the effective volume of the space, refrigeration units containing propane should not be installed in enclo sed areas with effective volumes less than indicated by relevant safety standards (e.g., ASHRAE 15, 34, an d UL 563) unless additional steps are taken to protec t against a flammability risk (e.g., higher ventila tion rates). EPA recommends that warning labels are present on t he equipment indicating that flammable refrigerants in use as well as notifying the user to read the eq uipment use instructions that provide safety guidel ines for handling propane. These guidelines should be follow ed to mitigate flammability risk. The installation of leak prevention devices would further protect again st the very limited risk of explosion. During servi cing operations, EPA recommends that the ventilation req uirements outlined in the SDS for propane are followed through the use of fans or other mechanica l ventilation devices and that portable refrigerant detectors are used to alert technicians to the pres ence of flammable gases in order to mitigate the ri sk of fire or explosion during catastrophic leak. It is a lso important that only properly trained and certif ied technicians handle propane. As a further precaution , certification requirements and training programs for technicians that handle propane should be developed using these guidelines.



### 8. ASPHYXIATION ASSESSMENT The risk of asphyxiation for the reasonable worst-c ase scenarios described in Section 5 were investiga ted for propane. In this section, risk of asphyxiation is assessed in three ways: 1) Modeling the oxygen concentration under the char ge size and room size specified in the worstcase scenario, 2) Performing a threshold analysis of minimum charg e size at which an asphyxiation risk could occur in the room size specified in the worst-case scenario (i.e., charge sizes greater than this are expected to cause an asphyxiation risk), and 3) Performing a threshold analysis of the maximum r oom size at which an asphyxiation risk could occur with the charge size specified in the worst-c ase scenario (i.e., room sizes smaller than this are expected to cause an asphyxiation risk). This analysis does not consider ventilation or cond itions 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 e ven openings at the bottom of doors that allow air to flow in and out. As specified in Section 5, the rea sonable worst-case scenario assumes a vertical concentration gradient. If the proposed substitute passes the screening analysis with these restrictiv e assumptions in place, it can be reasonably assumed that no risks of asphyxiation will be present under realworld conditions. The results of the asphyxiation a ssessment are summarized in Table 7 below. Table 7. Asphyxiation Assessment a,b

Scenario Charge Size (g) Effective Room Size (m 3 ) Percent Oxygen Concentration in Lower 0.4 Meters Reasonable Worst-Case Scenario 1 150 22 (780 ft 3 ) 21% Reasonable Worst-Case Scenario 2 150 120 (4,240 ft 3 ) 21% Threshold Analysis 1: Charge Size 2,730 22 (780 ft 3 ) 12% Threshold Analysis 2: Room Size 150 1.2 (42 ft 3 ) 12% Bold font indicates modeling results.March 29, 2016 – Final 11 a Cells highlighted in green are the scenarios in wh ich the charge and room sizes evaluated in this ris k screen are acceptable according to the threshold analysis or the scenarios with acceptable oxygen concentrations, given various modeling ass umption options.
b The typical concentration of oxygen in air is cons idered to be 21 percent (Mackenzie & Mackenzie 1995 ). In order for a risk of asphyxiation to occur, the n ormal concentration of oxygen in air (21 percent) m ust be reduced to 12 percent. 11 Based on the reasonable worst-case scenario modeli ng, a release of propane from commercial ice machines has an insignificant impact on the concentration of oxygen in the air and therefore does not present a significant risk of as phyxiation. This modeling does not take into accoun t any ventilation which is likely to occur, as mentioned above, so the actual asphyxiation risk to person(s) is likely to be even smaller than modeled. For the asphyxiation threshold analyses shown in Ta ble 7, the conditions at which an asphyxiation conc ern would exist were determined.

• As shown under Threshold Analysis 1, the charge siz e of the commercial ice machine in a 22 m 3 (780 ft 3 ) room would have to be at least 2,730 grams for as phyxiation to be a concern, which is approximately 18 times greater than the maximum cha rge size allowed by UL (i.e., 150 grams).

• Using the charge size of 150 grams for commercial i ce machines, as shown under Threshold Analysis 2, the volume of the room would have to be approximately 1.2 m 3 (42 ft 3 ), or approximately 18 times smaller than the size of the minimum modeled restaurant kitchen for asphyxiation to be of concern. Based on the worst-case modeling results and thresh old analysis, EPA does not believe that the use of propane in commercial ice machines poses a signific ant risk of asphyxiation or impaired coordination t o personnel, provided systems are installed in approp riate spaces according to guidelines from the manufacturer and the SDS for propane.



### 9. END-USE EXPOSURE ASSESSMENT This section presents estimates of potential end-us er exposures to propane in the event of a catastrop hic release from the proposed substitute’s use in comme rcial ice machines. An end-use exposure analysis wa s performed to examine potential catastrophic release s of propane under the reasonable worst-case scenar io outlined in Section 5. For the end-use exposure assessment scenario, 30-mi nute TWA exposures for the proposed substitute were calculated using the box model described in the Bac kground Document, which was adapted to estimate concentrations on a minute-by-minute basis. Estimat es for acute/short-term end-use exposures resulting from catastrophic leakage of refrigerant from a com mercial ice machine were examined. As discussed in Section 5, the full charge of the unit is assumed t o be emitted over the course of 1 minute. The analy sis was undertaken to determine the 30-minute TWA expos ures of propane, which were then compared to the standard toxicity limits presented in Table 4 to as sess the risk to end-users. The estimated TWA value s are fairly conservative as the analysis reflects minima l airflow (i.e., natural ventilation), but does not consider mechanical ventilation such as fans, conditioned ai rflow (either heated or cooled) and other variables that would reduce the levels to which individuals would be exposed. Table 8 displays the estimated exposure s to propane at end-use.

11 Twelve percent oxygen in air is the NOAEL for hypo xia (ICF 1997).March 29, 2016 – Final 12 Table 8. End-Use Exposure Assessment for Propane a

Scenario Charge Size (g) Room Size

(m 3 ) Vertical

Concentration Gradient 30

- min TWA End

Use Exposure (ppm) b Reasonable Worst-Case Scenario 1 150 22 (780 ft 3 ) Yes 2,150 Reasonable Worst-Case Scenario 2 No 360 Reasonable Worst-Case Scenario 3 150 120 (4,240 ft 3 ) Yes 390 Threshold Analysis 1: Charge Size 480 22 (7 8 0 ft 3 ) Yes 6,900 Threshold Analysis 2: Room Size 150 7 ( 250 ft 3 ) Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling a ssumption options.
b 30-minute AEGL-1; see Table 4 for more information.

Under the reasonable worst-case scenario described in Section 5 for commercial ice machines, the anticipated 30-minute TWA exposures of propane foll owing a catastrophic release of a 150-gram unit do not exceed its 30-minute AEGL (i.e., 6,900 ppm). In addition, these exposure estimates were derived us ing conservative assumptions (e.g., minimum room volume , low ventilation rate) that do not necessarily ref lect the actual room attributes where propane ice machin es will be installed. Specifically, the estimated exposure represents concentrations of leaked refrig erant in the bottom 0.4 meter (1.3 feet) of the roo m, accounting 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 portio n (e.g., prone or supine on the floor or a crawling infant) in the event of the catastrophic release of refrige rant is low. Furthermore, commercial kitchen spaces are often connected to other rooms (e.g., an eat-in spa ce, hallway) through open pathways or swinging door s, which would increase the effective volume of the sp ace into which a refrigerant would be released, the reby reducing the likelihood that end-users would be exp osed to modeled concentrations. To further analyze potential risks of exposure duri ng end-use, threshold analyses were conducted to determine the room size and charge size requirement s that ensure that the use of propane in this end-u se does not present risk to end-users or servicing tec hnicians. Based on these results, EPA recommends th at for a room volume of 22 m 3 (780 ft 3 ), the charge size is consistent with the proposed limit in UL 563 and does not exceed 150 grams. The analysis also indica tes a 150-gram refrigeration unit should not be installed in a room of effective volume less than 7 m 3 (250 ft 3 ) (see Threshold Analysis 2 in Table 8). To prevent exposure and potential serious side effe cts during larger releases, EPA recommends that the RCL for propane (i.e., 5,300 ppm or 9.5 g/m 3 ) is not exceeded in any location where a propane s ystem is installed, unless proper leak protection devices ar e in place in order to prevent exposures of propane beyond the recommended limits. Proper leak protecti on devices, engineering control requirements, and adherence to the SDS will further ensure that expos ure limits are maintained below those described in Table 8.



### 10. OCCUPATIONAL EXPOSURE ASSESSMENT This section assesses potential exposures to worker s during manufacture of propane, and installation, servicing, and disposal of propane ice machines. To ensure that use of the proposed substitute in commercial ice machines does not pose an unacceptab le toxicity risk to workers during servicing and disposal, occupational exposure modeling was perfor med using a box-model approach. For a detailed description of the methodology used for this screen ing assessment, the reader is referred to the occupational exposure and hazard analysis described in Chapter 5 of the Background Document.March 29, 2016 – Final 13 For charging, servicing, and disposal activities, t he release rate per event was multiplied by the num ber of events estimated to occur over a workday. During ch arging and servicing, the release per event was conservatively assumed be 0.4 percent of the equipm ent charge. For equipment charging and servicing, t he number of events per workday was conservatively ass umed that eight events of servicing a unit by one servicing technician occur in an 8-hour work day (s ee Section 10.2). For disposal, the release per event was conservativ ely assumed to be 100 percent of the equipment char ge (representing a catastrophic release). It was assum ed that 10 units are disposed of during an 8-hour w ork day; however, it was assumed that of the 10 units, only the last unit per workday would experience the catastrophic release (i.e., 100 percent). The remai ning 9 units were assumed to release an incidental amount of refrigerant (i.e., 1 percent per unit) fr om the connecting and disconnecting of lines, as it is likely that if a worker was exposed to the entire charge o f a system during disposal activities, they would immediately stop working, clear the area until all refrigerant has been removed from the space (e.g., through ventilation), and adhere to the exposure pr ocedures recommended in the SDS for the proposed substitute (see Section 10.3). The modeled exposure concentrations were compared t o short-term occupational exposure limits at charging and servicing and long-term exposure limit s at disposal. 10.1 Occupational Exposure at Manufacture of Substi tute Propane is produced around the world, including in the United States, and is used for a wide variety o f refrigerant and non-refrigerant uses. During manufa cture of propane, the SDS should be referenced and proper engineering controls and PPE used. Propane is not expected to pose a risk to workers d uring manufacture or blending when the engineering controls and PPE recommendations referenced in the SDS propane 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 con tainers). Refrigerant quality control testing may r esult in release of de minimus quantities of refrigerant, which would typically be to exhaust ducts or fume hoods. Engineering controls should include normal and loca l ventilation (e.g., chemical hoods) and vapor-in-a ir detection systems for standard manufacturing proced ures so workers can avoid physical contact with the refrigerant and to achieve emission control. In gen eral, use of PPE consistent with OSHA guidelines is recommended, such as respiratory protection (includ ing a self-contained breathing apparatus [SCBA] in case of insufficient ventilation), tightly sealed g oggles, and protective gloves (OSHA 1994). EPA beli eves that when proper handling and disposal guidelines a re followed in accordance with both good industrial hygiene and manufacturing practices and the SDS for propane, there is no significant risk to workers during the manufacture of propane. 10.2 Occupational Exposure at Charging and Servicin g Commercial ice machines would typically be charged by the Original Equipment Manufacturer (OEM). During OEM system manufacture (i.e., charging at OE M location), points of release for charging and servicing these leak-tight systems would be from co nnection/disconnection of temporary lines for charg ing and recovery equipment. Charging occurs within an enclosed area equipped wi th automatic ventilation, refrigerant detectors, an d alarm systems. [ ]. During servicing, used refrigerant from propane ice machines is pumped into a canister, where it is st ored until it is recycled (i.e., filtered and reused). I solation and evacuation of lines or equipment prior to servicing or repair and the use of compatible seals , gaskets, O-rings, thread sealants, and minimizati on ofMarch 29, 2016 – Final 14 threaded joints all contribute to limiting releases . Room ventilation, leak monitors, and alarms also minimize exposure. Installation and servicing activities for commercia l ice machines are not expected to result in signif icant worker exposure when certified technicians follow t he procedures outlined in the propane SDS and maintenance manual, undergo proper training, and we ar appropriate PPE (e.g., gloves and safety glasses ). Nevertheless, the potential occupational exposure d uring servicing was analyzed. The maximum 30- minute TWA exposures for propane were estimated and compared to the STEL (see Table 9). The modeling results indicate that the maximum anticipa ted occupational exposure concentrations at no poin t exceed the STEL for propane. Table 9. Occupational Risk Assessment at Servicing a

Component 30

- minute TWA Occupational Exposure (ppm) Short Term Exposure Limit (ppm) Charge Size: 150 grams Propane 1.2 6,900 b Bold font indicates modeling results.

a Cells highlighted in green are the scenarios that a re deemed to be acceptable given various modeling assumption options.
b 30-minute AEGL-1; see Table 4 for more information. The estimated exposures were derived using conserva tive assumptions, and represent a worst-case scenar io with a low probability of occurrence. These types o f systems are typically serviced by trained personn el using proper industrial hygiene techniques and usin g proper engineering controls (e.g., local ventilat ion, refrigerant detectors, and alarm systems). Thus, EP A does not believe that installation or servicing o f commercial ice machines containing propane presents a significant concern to workers. 10.3 Occupational Exposure at Disposal Disposal of propane ice machines is expected to occ ur with limited frequency (up to approximately ten disposal events per day) at disposal facilities and with limited duration of exposure to the installed refrigerant. Typically, potential exposures to the refrigerant during recovery and disposal are expect ed to occur during activities related to decommissioning refrigeration systems (e.g., attaching of hoses associated with draining or otherwise discharging o f refrigerant from the refrigeration units into cyl inders) and would be similar to those during servicing, bec ause 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). Such activit ies and related exposure is anticipated to occur wi thin 15- 30 minutes (per event/day). Table 10 displays the maximum estimated 8-hour TWA occupational exposure levels for propane and each of its potential impurities during disposal. To mod el a worst-case scenario, it was assumed that of th e 10 disposal events, 9 units are properly disposed of w ith only incidental releases of refrigerant (i.e., 1 percent per unit) followed by the disposal of one unit that results in a catastrophic release of refrigerant ( i.e., 100 percent of the equipment charge). Because modeled e xposure levels are significantly lower than the 8-h our exposure limits for propane and each of its potenti al impurities, occupational exposure to the propose d substitute during disposal is not considered a toxi city risk. Further, estimated exposures were derive d using conservative assumptions (e.g., no ventilation) and represent a worst-case scenario with a low probabi lity of occurrence. These types of systems are typically disposed of by trained personnel using proper industrial hygiene techniques while wearing PPE.March 29, 2016 – Final 15 Table 10. Occupational Risk Assessment at Disposal a

Component 8

- hour TWA Occupational

Exposure (ppm) 8-Hour Long Term Exposure Limits (ppm) Charge Size: 150 grams Propane 58 1,000 b Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with e xposure levels deemed to be acceptable given various modeling assumption options.
b OSHA PEL and NIOSH REL Although anticipated occupational exposures are wel l below the exposure limit for propane for units wi th a charge of 150 gram, the recommendations for proper engineering controls and PPE in the SDS for propane should be followed. Adequate ventilation should alw ays be established during any use, handling, or storage of propane. Engineering controls should inc lude vapor-in air detection systems and local exhau st ventilation during use of propane to prevent disper sion throughout the workplace. In addition, an eye wash and safety shower should be near locations where pr opane is stored and ready for use. In general, use of PPE is recommended, such as splash goggles, mechani cally-resistance gloves when handling cylinders, and chemically-resistant gloves when handling the g as mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). EPA believes that if pr oper handling and disposal guidelines are followed in accordance with good industrial hygiene and manufac turing practices and the SDS for propane, there is no significant risk to workers during the disposal of propane in commercial ice machines.



### 11. GENERAL POPULATION EXPOSURE ASSESSMENT This section presents an assessment of potential ri sks to the general population posed by the use of p ropane in ice machines. The general population is defined in this risk screen as non-personnel who are subjec t to exposure of the proposed substitute near industrial facilities, including manufacturing or equipment production factories, equipment operating sites (fo r on-site installation or disposal activities only) , or recycling centers, rather than consumers at end-use

. Propane 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 c ommercial ice machines. The proposed substitute wil l be manufactured in a closed process and is proposed for use in closed systems; thus, significant relea ses are not anticipated. At room temperature, propane i s a gas; therefore, releases to ground or surface w ater are not anticipated, as propane is anticipated to d issipate into the atmosphere upon release to outsid e air (i.e., because natural ventilation rates would be h igher and there is no enclosed space to maintain a high concentration of propane). Should air releases duri ng manufacturing operations occur, engineering cont rols should be used (e.g., carbon absorption scrubbers) to collect propane and prevent the release of the chemical to the atmosphere. EPA believes that by us ing proper engineering controls and by following disposal and containment recommendations outlined i n the proposed substitute’s SDS and this risk scree n, exposure to propane is not expected to pose a signi ficant toxicity risk to the general population.March 29, 2016 – Final 16 

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