March 28, 2016 – Final 1 

## Significant New Alternatives Policy Program Refrigeration and Air Conditioning Sector
Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps

Substitute: R-443A

This risk screen does not contain Clean Air Act (CA A) Confidential Business Information (CBI) and, therefore, may be disclosed to the public.



### 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 R-443A as a substitu te in the residential and light commercial air conditioning (AC) and heat pumps end-use (specifica lly window AC units, split-system AC units, residential heat pumps, and portable AC units). Tab le 1 presents the composition of the proposed substitute. Table 1. Composition of R-443A

Constituent Chemical Formula CAS Number Concentration (Weight Percent) a Propylene C 3 H 6 115-17-1 55% Propane C 3 H 8 74-98-6 40% Isobutane C 4 H 10 75-28-5 5%

a There are no impurities of toxicological or ecolog ical significance anticipated for this formulation. Isomers of hydrocarbons present in formulation mixture will exist, but are not considered to be an impurity, contaminant or by product.
Section 2 summarizes the results of the risk screen for the proposed substitute blend in 

### Error! Reference source not found. . The remainder of the risk screen is organized in to the following sections:

• Section 3: Atmospheric Assessment

• Section 4: Volatile Organic Compound Assessment

• Section 5: Discussion of End-Use Scenario Modeled

• Section 6: Potential Health Effects

• Section 7: Flammability Assessment

• Section 8: Asphyxiation AssessmentMarch 28, 2016 – Final 2 • 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-443A is not recommended for SNAP approval as a re frigerant in residential and light commercial AC units and heat pumps, specifically window AC units, split-system AC units, residential heat pumps, and portable AC units. R-443A 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 R-443A are ant icipated to result in greater impacts on local air quality in the United States than other available o ptions. According to the results of the assessments in this risk screen, significant flammability risk is unli kely (see Section 7 of this document). However, the results o f the end-use exposure assessment indicate signific ant toxicity risk at end-use is likely even when units are installed in locations with adequate space or ventilation conditions in accordance with equipment maintenance manuals for R-443A residential and lig ht commercial AC equipment (see Section 9 of this docu ment). Toxicity risks at end-use exceed additional safeguards, including specified refrigerant concent ration limits (RCL) of R-443A components, which are provided by adherence to industry standards includi ng American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standards 15, 1 34, 2 and 62, 3 and Underwriters Laboratory (UL) Standard 484. 4 Because of the potential local air quality impacts and toxicity risk posed by use of R-443A in the proposed end-uses, R-443A is not recommended for SNAP approval as a refrigerant in residential and light commercial AC units and heat pumps.



### 3. ATMOSPHERIC ASSESSMENT This section presents an assessment of the potentia l risks to atmospheric integrity posed by the use o f R443A in residential and light commercial AC and hea t pumps. The ozone depletion potential (ODP), globa l warming potential (GWP), and atmospheric lifetime ( ALT) of the proposed substitute are presented 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 and HCFC-22. In addition, R-443A also has lower climate impact and a shorter ALT than those p redicted for other substitutes examined in the Background Document as well as the commonly utilize d refrigerant, R-410A.

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 484 Standard for Safety: Room Air Conditioners e stablishes safety requirements for room air conditi oners that are designed to provide delivery of conditioned air to an enclos ed space, room, or zone.March 28, 2016 – Final 3 Table 2. Atmospheric Impacts of R-443A Components Compared to Other Refrigerants used in

Residential and Light Commercial AC and Heat Pumps Refrigerant Ozone Depleting Potential (ODP) a Global Warming Potential (GWP) b Atmospheric Lifetime in Years (ALT) Propylene 0 1.8 0.35 days b Propane 0 3.3 0.03 b Isobutane 0 ~4 0.016 b CFC

- 12 0.82 10,900 100 HCFC

- 22 0.13 b 1,810 12 b R

- 410A c 0 2,088 NA d 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-410A is a blend consisting of HFC-32 (50%), and HFC-125 (50%).
d Atmospheric lifetimes are not given for blends, bec ause 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 The components of R-443A are regulated as VOCs unde r CAA regulations (40 CFR 51.100 [s]). Emissions of R-443A should be controlled according to CAA and other regulations by adhering to standard industry practices. EPA prepared a separat e analysis in 2014 5 and a follow-on analysis in 2016 6 to evaluate the potential impact of the use of hydroca rbon refrigerants on ground-level ozone concentrati ons in the United States. These analyses estimated refrigerant emissions from refrigeration and air conditioning equipment, whic h were assumed to contain propylene, isobutane, and/o r propane under different scenarios. The hydrocarbo n emissions from these scenarios were estimated based on EPA’s Vintaging Model, and their potential contributions to ozone concentrations were assessed using EPA’s Community Multiscale Air Quality (CMAQ) model. 7 CMAQ modeling was performed for April through the e nd of September, as these months presented the largest releases of hydrocarbo n refrigerant as well as weather conditions favorab le for ozone formation. The ozone concentrations were estimated for the Atlanta, Houston, and Los Angeles regions, due to their distinctive geographic settin g and chronic high levels of ground-level ozone, an d then scaled for national emission estimates. The analysis considers the propensity of organic co mpounds to form ozone according to their maximum incremental reactivity (MIR). The MIR scale assesse s a compound’s contributions to the photochemical ozone formation in urban plumes and is reflective o f its use in North America, where ground-level ozon e formation is considered an urban issue. Table 3 lis ts the MIR for several compounds, including the hydrocarbons examined in this analysis.

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 VM version VM_IO file_v4.4_10.13.14 and CMAQ model version 5.0.2 were used in this analysis.March 28, 2016 – Final 4 Table 3. Propensity of Refrigerants to Form Troposp heric Ozone

Compound North America MIR Scale (g-O 3 /g-substance) HCFC-22 <0.1
HFC-134a <0.1 Propylene 11.57
Ethane a 0.28
Isobutane 1.34 Propane 0.56 Source: IPCC (2005)

a EPA uses the reactivity of ethane as the threshold for determining whether a compound has negligible reactivity. Compounds that are less reactive than, or equally reactive to, ethane under certain assume d conditions may be deemed negligibly reactive and th erefore suitable for exemption from the definition of a VOC (EPA 2012a). As demonstrated in Table 3, the MIR for propylene, R-443A’s largest component (see Table 1), is more than 20 times greater than the MIR for propane, and approximately 9 times greater than the MIR for isobutane. Therefore, propylene is significantly mo re likely to form tropospheric ozone than other refrigerants examined in this analysis. These analyses estimated hydrocarbon refrigerant em issions in 2030 (EPA 2014) and 2040 (EPA 2016) from different scenarios and compared their resulti ng relative increases in ozone concentrations again st the National Ambient Air Quality Standard (NAAQS) for o zone of 70 ppb. 8 All three regions examined in these analyses (i.e., Los Angeles, Atlanta and Hous ton) are forecast to be in attainment of the 2015 8 -hr 70 ppb ozone standard by 2040. Isobutane, a less reactive hydrocarbon than propyle ne, was modeled in all refrigeration and air conditioning equipment. The results of this scenari o indicate there could be an incremental increase u p to 0.72 ppb in 2030. In the alternative case, which as sumed that the most reactive hydrocarbon, propylene

, was used in all refrigeration and air conditioning equipment, there could be an incremental maximum increase of the 8-hour average as high as 6.6 ppb o zone in 2030 (EPA 2014) or 7.8 ppb ozone in 2040. Although potential impacts from isobutane were only modeled in 2030, the relative impact of isobutane in 2040 is still anticipated to be significantly less than that of propylene, because isobutane is signif icantly less reactive. EPA performed an additional analysis to determine r efrigerant emissions resulting from the use of propylene in a limited number of refrigeration and air conditioning end-uses including chillers, cold storage warehouses, and certain residential and lig ht commercial air conditioning applications and the ir potential contributions to tropospheric ozone gener ation. Emissions from these select end-uses were estimated to result in an incremental maximum incre ase of the 8-hour average of up to 4.5 ppb in 2040. In addition, EPA examined a more realistic scenario in which refrigerant emissions from propylene and R443A were modeled in cold storage warehouses, resid ential and light commercial air conditioning, and large commercial air conditioning applications incl uding chillers, as well as refrigerant emissions fr om R441A and propane in room air conditioners. Refriger ant emissions from this scenario resulted in an incremental maximum increase of the 8-hour average of 2.6 ppb in 2040. The increase in ozone is estimated to be about 95 percent associated with th e use of propylene as a refrigerant, including its use as a component of R-443A, and 4 percent from propane, in cluding its use as a component of R-443A and R441A, under this scenario. The results of the CMAQ modeling are summarized in Table 4.

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).March 28, 2016 – Final 5 Table 4. Estimated Maximum Increase in the Daily 8- hour Ground-Level Ozone in 2040 from Hydrocarbon Refrigerant Emissions

Equipment Refrigerant 8-hr Ozone Maximum Change (ppb) All refrigeration and air conditioning equipment Propylene 7.8
Isobutane 0.72 a
Chillers, cold storage warehouses, and certain residential and light commercial air conditioning applications Propylene 4.5 Propane, Propylene, R

441A, R-443A 2.6 b

a The 8-hr maximum increase in ground-level ozone is observed in 2030 for the isobutane scenario.
b 95 percent of the change in ozone is associated wit h the use of propylene as a refrigerant and as a component of R-443A, and 4 percent from propane as a refrigerant and as a component of R-441A and R443A, under this scenario. Although most ozone nonattainment areas are not VOC -limited (i.e., the formation of ozone in these are as is not by limited by VOC emissions, but by other co mpounds such as nitrogen oxides [NO x ]), allowing the use of R-443A in residential and light commercial A C could introduce VOC loading that would place a further burden on reaching attainment and extend th e timeline for compliance for some areas. Because propylene, R-443A’s largest component, is h ighly reactive, VOC emissions from the use of R443A in residential and light commercial AC units a re anticipated to contribute to ground-level ozone concentrations in the United States significantly m ore than less reactive hydrocarbons and other avail able options for these end-uses, such as propane or HFC- 32. Therefore, R-443A is not recommended for SNAP approval as a refrigerant in residential and light commercial AC and heat pumps.



### 5. DISCUSSION OF END-USE SCENARIOS MODELED R-443A has been proposed for use in residential and light commercial AC units and heat pumps, includin g window AC units, split-systems, 9 residential heat pumps, and portable AC units. Thi s risk screen evaluates refrigerant releases from all of the proposed room AC systems in a single room based on the smallest a nd largest proposed charge sizes. Charge sizes for the systems modeled in this risk screen are shown in T able 5. Table 5. Charge Sizes for R-443A Residential Air-Co nditioning Applications

Application Minimum Modeled Charge Size (g) Maximum Modeled Charge Size b (kg) Window Units 160 a 245 Ducted Split-Systems 416 b 1,560

a Acceptable charge size for R-443A window AC units i nstalled in a 41 m 3 room (ANSI/UL 2012).
b Charge size indicated by the submitter (A.S. Trust & Holdings, 2015). The 160-gram charge size for window units is consis tent with UL Standard 484: Room Air Conditioners, which limits the charge size of single-room AC unit s for ASHRAE classified A3 refrigerants based on th e lower flammability limit of the refrigerant and the volume of the room at end-use (ANSI/UL 2012). The submitter indicates a charge size of 245 grams for window units. The ducted split-systems proposed by the submitter are not governed by UL 484, because they are intended to serve multiple rooms. Therefore, this r isk screen models the submitter’s minimum charge si ze

9 Split-systems consist of an evaporator section ins talled indoors and a condensing unit installed outd oors, which are connected by refrigerant piping and electrical wiring (UL 2013). Such systems can be further classified as ducted, ductless mini-split, or ductless multi-split.March 28, 2016 – Final 6 of 416 grams for ducted split-system AC units, cons istent with the International Electrotechnical Commission (IEC) Standard 60335-2-40: Particular re quirements for electrical heat pumps, air conditioners, and dehumidifiers. 10 The submitter indicates a maximum charge size of 1 ,560 grams for ducted split-system AC units serving multiple rooms (A.S. Trust & Holdings 2015). 11 Although the submitter did not propose using R-443A in split-sys tems covered under UL 484, the standard’s maximum allowable charge size of 290 grams for single-room split-systems containing R-443A is discussed in Sections 7 and 9 of this risk screen. Window and split-system AC units can be installed i n a wide range of locations with varying room volumes. To represent a reasonable worst-case scena rio for window and ducted split-system AC units, it is assumed that a catastrophic leak of refrigerant occ urs in a bedroom where the AC unit is located. The analysis in this risk screen conservatively assumes that the AC unit is located in a bedroom with an effective volume of 41 m 3 (1,450 ft 3 ) (i.e., excluding the space filled by furniture, e tc.) and a height of 2.4 meters (7.8 feet).
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 a bedroom with 0.11 air c hange(s) per hour (ACH) or 0.67 ACH. 12 During the cooling season (May to September), ACH in spaces wi th a floor area of 900 square feet or less are repo rted to be between 0.11 ACH for tight construction and 0 .67 ACH for loose construction (ACCA 2006). Therefore, this risk screen models both air exchang e rates, 0.11 ACH and 0.67 ACH, in order to account for installation of units in homes with different c onstruction practices, for both charge sizes (245 a nd 1,560 grams). UL 484 assumes that window AC and split-system unit s are installed at a height of 1 meter and 1.8 mete rs above the ground, respectively. Although UL 484 is not applicable to ducted split-systems that serve multiple rooms, for this analysis, it is assumed th at all split-system units and/or vents for ducted-s plit systems would be installed at similar heights. Based on this location and since R-443A is denser t han air (specific gravity of R-443A relative to air is 1.49 [air=1]) and will settle in higher concentrations closer to the ground, a vertical concentration gradient is al so assumed. In order to simulate the vertical concentration gradient of refrigerant following rel ease, it is assumed that 95 percent of the leaked refrigerant mixes evenly into the lower meter (3.3 feet) or 1.8 meters (5.9 feet) of the room, and the rest of the refrigerant mixes evenly in the remaining volum e (Kataoka 2000). 13 Table 6 details the end-use modeling assumptions used throughout the risk scree n (i.e., in Sections 7, 8 and 9).

10 IEC 60335-2-40 limits the charge size of room AC un its, including split-systems, for flammable refrige rants based on the lower flammability limit of the refrigerant and the volum e of the room at end-use (IEC 2013).
11 The submitter also indicates a typical charge size of 340 grams for portable room AC units (A.S. Trust & Holdings 2013).
12 The EPA Exposure Factors Handbook (1997) states tha t the typical residential air exchange rate is 0.45 ACH, which factors in tests from homes that are greater than 45 years old as well as those that are less than 10 years old. However, older homes (i.e., built before 1994) are more likely to use window or wall AC units than newer homes. Based on data of AC use in U.S. homes by year of construction, 27 percent of homes using AC equip ment use window or wall AC units, while the remaini ng use central air conditioning equipment (EIA 2013). On average, 38 p ercent of homes built before 1990 use window or wal l AC units in comparison to the average of 9 percent of homes bui lt after 1990. Air exchange rates are expected to b e greater in older homes that are typically built with loose construction practic es (e.g., no or inadequate effort to seal structura l panels, corners, cracks, joints, and penetrations; window and door assemblies are no t rated). Additionally, if a home uses window or wa ll AC units, EPA does not expect that there is any significant mechanical ven tilation present in the home.
13 UL 484 assumes AC units installed near floor level , such as portable room AC units, are installed at a height of 0.6 meters above the ground (ANSI/UL 2012). 95 percent of the leaked refrigerant from portable room AC units is assumed to mix evenly in the bottom 0.6 meters of the room. The results of the f lammability, asphyxiation, and end-use exposure ass essments for portable AC units are not shown in this risk screen, because th e results fall within the range of exposures for wi ndow units and ducted splitsystems in Sections 7, 8, and 9.March 28, 2016 – Final 7 Table 6. End-Use Scenario Model Assumptions Parameter Assumption s Room Type Bedroom Size (m 3 ) 41 a (1,450 ft 3 ) Ventilation Rate (air changes per hour) 0.11 b ; 0.67 c Air Conditioning Unit Window AC Ducted Split

- System AC Charge Size (g) 160 d

, 245 e 416 e , 1,560 e Length of Release (minutes) 1 1 Vertical Concentration Gradient Yes f Yes g

a Background Document (EPA 1994)
b Tight construction home (ACCA 2006)

c Loose construction home (ACCA 2006)
d Acceptable charge size for R-443A window AC units i nstalled in a 41 m 3 room (ANSI/UL 2012)

e Charge size indicated by the submitter (A.S. Trust & Holdings 2015)
f The end-use scenario for window units assumes a ver tical concentration gradient of 1 meter (3.3 feet) in accordance with UL 484 (ANSI/UL 2012).

g The end-use scenario for split-systems assumes a v ertical concentration gradient of 1.8 meters (5.9 f eet) in accordance with UL 484 (ANSI/UL 2012).



### 6. POTENTIAL HEALTH EFFECTS To assess potential health risks from exposure to t he proposed substitute in residential and light commercial AC and heat pumps, EPA identified the re levant toxicity threshold values for comparison to modeled exposure concentrations for different scena rios. According to ASHRAE Standard 34, R-443A is listed under safety group A3 with a RCL of 1,700 pp m (ASHRAE 2013a). ASHRAE 34 RCLs are intended to reduce the risks of acute toxicity, asp hyxiation, and flammability hazards in normally occupied, enclosed spaces during refrigerant use an d protect end-users from the potential dangers of a catastrophic leak from a refrigeration unit (ASHRAE 2013a). ASHRAE Standard 15 implements the aforementioned standard, requiring that “the concen tration of refrigerant in an enclosed space followi ng a complete discharge of a high-probability system sha ll not exceed the RCL” (ASHRAE 2013b). As such, this risk screen references the RCL for R-443A in a ddition to the lower flammability limit (LFL), hypo xia no observed adverse effect level (NOAEL) and exposu re limits, as an additional, conservative limit to ensure that significant flammability, asphyxiation, and end-use exposure risks, respectively, do not o ccur. 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 7 lists the relevant toxicity limits and RCL of R- 443A and is followed by Table 8, 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.March 28, 2016 – Final 8 Table 7. Exposure Limits of R-443A Components

An explanation of each exposure limit and exposure- limit related terminology is described in Table 8.

a Calculated as three times the TLV-TWA (ACGIH 2004).
b ASHRAE (2013a)

c OSHA PEL available at: http://www.cdc.gov/Niosh/np g/npgd0524.html
d 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.

e AEGL-1 available at: http://www.epa.gov/opptintr/a egl/pubs/results96.htm
f ACGIH TLV for aliphatic hydrocarbon gases: alkane ( C1 - C4) is 1,000 ppm TWA (ACGIH 2012)

g Because n-Butane and isobutane have the same molec ular formula, EGL for isobutane is conservatively a ssumed to be that for n-Butane. However, OSHA (2004) notes the following regarding isobutane: “OSHA does not have a PEL for isobutane, which is affirmed as "generally recognized as safe" as a direct human food ingredie nt (21 CFR 184.1165). No toxic effects reported bel ow 18,000 ppm.”

Table 8. Explanation of Exposure Limit-Related Term inology a R-443A Component 8

- hr WGL (Long

- term Exposure) ppm 30

- min EGL (Short

- term Exposure) ppm Refrigerant Concentration Limit (RCL) ppm Propylene 500 (ACGIH-TLV) 1,500 (30-min ACGIH Excursion Limit) a 1,000 b

Propane 1,000 c (OSHA PEL /NIOSH REL) 10,000 d,e (10

- min AEGL

- 1) 6,900 e (30-min AEGL-1) 5,300 b

Isobutane 1,000 f (ACGIH

- TLV) 6,900 g 4,000 b

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 Exposure Limit Definition Explanation Short

- Term Exposure RCL Refrigerant Concentration Limit The RCL for a refrigerant is intended to reduce the risks o f acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. The RCL for each refrige rant is the lowest of the Acute-Toxicity Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable Concentratio n Limit (FCL). Determination assumes full vaporization with no removal by ventilation, dissolution, reaction, or decompositio n and complete mixing of refrigerant in the space to which it is r eleased. STEL Short

- Term E xposure Limit A 15

- minute time

- weighted average ( TWA ) exposure that should not be exceeded at any time during a workday, even if the 8-hour TWA is within the threshold-limit value (TLV)–TWA, 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 t he general population, including susceptible individuals, coul d experience notable discomfort, irritation, or certain asymptom atic nonsensory effects, set by EPA. However, the effects are not d isabling and are transient and reversible 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 t he general population, including susceptible individuals, coul d experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape, set by EPA. Acute Exposure Guideline Level 3 AEGL

- 3 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that t he generalMarch 28, 2016 – Final 9 a All information in this table taken from EPA (1994) except where otherwise noted.
b EPA (2012)

c Applicable to emergency exposure periods ranging fr om 10 minutes to 8 hours.
d NIOSH (2015)
According to the safety data sheet (SDS), exposure to R-443A may be hazardous if inhalation, skin contact, or eye contact with the proposed substitut e occurs. The most likely pathway of exposure is through inhalation. R-443A can cause symptoms of as phyxiation 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, vom iting, depression of all senses, and also unconsciousness. Under some circumstances of over-e xposure (i.e., oxygen levels fall below 6 percent b y volume), death may occur. In addition, at high conc entrations, propane, a component of R-443A, can act as a narcotic and cause central nervous system depress ion, including dizziness, drowsiness, and headaches

. If R-443A is inhaled, person(s) should be immediate ly 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 R-443A to the skin may cause f rostbite. In the case of dermal exposure, the SDS f or R-443A recommends that person(s) immediately wash t he 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 R-443A to the eyes could cause eye irritation. In case of ocular exposure, t he SDS for R-443A recommends that person(s) immediatel y 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 pr oposed substitute is contained in the public docket for this decision. The potential health effects of R-443A can be minim ized by following the exposure guidelines and ventilation and personal protective equipment (PPE) recommendations outlined in the SDS for R-443A and this risk screen. population, including susceptible individuals, coul d experience life

threatening health effects or death, set by EPA. Excursion Li mit d Excursion Limit Because methane (and other short

- chain alkane gases through butane) does not have a TLV-short-term exposure lim it, an excursion limit may be applied. Excursions in worke r exposure levels may exceed 3 times the TLV-TWA for no more t han a total of 30 minutes during a workday, and under no circumsta nces should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded according to ACGIH. IDLH Immediately Dangerous to Life

and Health If exposed to this concentration, room occupants are expected to be able to escape the room within 30 minutes withou t experiencing escape-impairing or irreversible health effects, as indicated by NIOSH. Long

- Term Exposure PEL Permissible Exposure Limit This is an 8

- hour TWA exposure limit set by OSHA. REL d 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 near ly all workers may be repeatedly exposed, day after day, for a wor king lifetime without adverse effect according to ACGIH.March 28, 2016 – Final 10 

### 7. FLAMMABILITY ASSESSMENT

ASHRAE Standard 34 classifies R-443A as an A3 refri gerant. R-443A is flammable when its concentration in air is in the range of 2.03 percen t to 10.3 percent by volume (20,300 ppm to 103,000 ppm). In the presence of an ignition source (e.g., static electricity or a cigarette), an explosion or a fire could occur if the concentration of R-443A were to exceed the LFL of 20,300 ppm. The remainder of this section addresses flammability risks and summarizes the recommended measures to ensure safe handling and use of the refrigerant during manufacture and s ervicing.

7.1 Flammability Risks at Equipment and Substitute Manufacture As indicated by the submitter, the manufacture of R -443A refrigerant (i.e., formulation mixing) and th e charging of R-443A residential and light commercial AC units occur in a closed system. As a result, releases of R-443A during manufacturing operations in the presence of an ignition source are not anticipated. All R-443A storage and transport equipment should b e 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. Similar equipment safety and procedural requiremen ts should be developed for R-443A and other flammable refrigerants. It is expected that refrigerants be properly stored and caution used within manufacturi ng facilities to minimize explosion risk and that workers adhere to the requirements set by OSHA unde r 29 CFR 1910. OSHA requirements include proper ventilation and storage practices within manufactur ing facilities to prevent fire and explosion. Good manufacturing practices should be adhered to during the manufacture of equipment containing R-443A, e.g., using proper 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 R-443A. Both servicing and end-use of R-443A window and ducted split-system AC units are expected to take place in the same spa ce (i.e., the installation and use location). In or der to determine the potential flammability risks during s ervicing or end-use in case of a catastrophic relea se of refrigerant, modeled concentrations of R-443A immed iately following the release of refrigerant were compared with the LFL for R-443A (i.e., 20,300 ppm)

. The results of the flammability assessment are presented in Table 9.

Table 9 . Flammability Assessment a

Equipment Scenario Charge Size (g) Effective Room

Size (m 3 ) Vertical

Concentration Gradient Maximum

Instantaneous Concentration (ppm) b,c

Window Units Reasonable Worst-Case Scenario 1a 160 41 (1,450 ft 3 ) Yes 4,910

Reasonable Worst-Case Scenario 1b 245 7,520
Ducted SplitSystems Reasonable Worst-Case Scenario 2a 416 41 (1,450 ft 3 ) Yes 5,410

Reasonable Worst-Case Scenario 2b 1,560 Yes 26,600 Reasonable Worst-Case Scenario 2c No 20,000

Window Units Threshold Analysis 1a: Charge Size 660 41 (1,450 ft 3 ) Yes 20,300

Threshold Analysis 1b: Room Size 245 15 (540 ft 3 ) Yes 20,300Ducted SplitSystems Threshold Analysis 2a: Charge Size 1,190 41 (1,450 ft 3 ) Yes 20,300

Threshold Analysis 2b: Room Size 1,560 54 (1,900 ft 3 ) Yes 20,300March 28, 2016 – Final 11 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 R-443A is 20,300 ppm.

c Values provided in this column refer to the concent ration in the lower meter of the room, which presen ts the most conservative risk as 95 percent of the leaked refrigerant is present in thi s space.

As presented in Table 9, the maximum instantaneous concentration in the lower compartment of the room does not exceed the LFL for R-443A (i.e., 20,300 pp m) for window units and Reasonable Worst-Case Scenarios 2a and 2c for ducted split-system AC unit s. However, the maximum instantaneous concentration in the lower 1.8 meters of the room exceeds the LFL for R-443A (i.e., 20,300 ppm) in Reasonable WorstCase Scenario 2b, where a vertical concentration gr adient is considered. Because the ducted split-syst em AC unit is expected to be installed at or near ceil ing height (approximately 2 meters or 7 feet), it i s reasonable to assume the refrigerant would mix even ly with air before settling to the ground. Therefor e, Reasonable Worst-Case Scenario 2c was modeled witho ut a vertical concentration gradient. Although Reasonable Worst-Case Scenario 2b exceeds the LFL for R-443A, it is also unlikely that the entire charge of the R-443A system will be released . The submitter indicates the condenser, compressor

, refrigerant lines and other components of the ducte d split-system are located outside, and such configurations employ a safety valve that limit the amount of R-443A that could be released indoors (A .S. Trust & Holdings 2013). As a result, releases of du cted split-system AC units with a 1,560 gram charge size do not present a significant flammability risk in the reasonable worst-case scenario for R-443A. The conditions at which a flammability concern woul d exist (i.e., when the maximum instantaneous concentration in the lower meter of the room equals the LFL for R-443A) were also determined.

• As shown under Threshold Analysis 1a, a flammabilit y concern could occur if the charge size of a R-443A window AC unit in a 41 m 3 (1,450 ft 3 ) room is 660 grams or more, which is larger than the maximum charge size allowed by UL 484 in a 41 m 3 room (i.e., 160 grams of R-443A for window units and 290 grams of R-443A for split-syst ems serving a single room).

• Using the submitter’s charge size of 1,560 grams fo r R-443A ducted split-system AC units, as shown under Threshold Analysis 2b, the volume of th e room would have to be approximately 54

m 3 (1,900 ft 3 ), or slightly larger than the modeled room size fo r flammability to be of concern. According to the results of this flammability analy sis, the risk of fire is minimal if a window or spl itsystem AC unit is installed in a room with volumes in accordance with standards and regulations and if it meets the requirements of UL 484 for equipment serv ing a single room. As bedrooms can be smaller than those modeled in this assessment 14 and because persons or equipment in the room may re duce the effective volume of the space, AC units containing R-443A sho uld not be installed in enclosed areas with effecti ve volumes less than indicated by relevant safety stan dards (e.g., ASHRAE 15, 34, and UL 484) unless additional steps are taken to protect against a fla mmability risk (e.g., higher ventilation rates).



### 8. ASPHYXIATION ASSESSMENT The risk of asphyxiation for the reasonable worst-c ase scenarios described in Section 5 were investiga ted for R-443A. In this section, risk of asphyxiation i s assessed in three ways: 1) Modeling the oxygen concentration under the char ge size and room size specified in the worstcase scenario,

14 International Residential Code requires a minimum of 6.5 m 2 (70 ft 2 ) for a habitable room, or 14 m 3 (490 ft 3 ) (ICC 2015).March 28, 2016 – Final 12 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 10 below. Table 10. Asphyxiation Assessment a,b

Scenario Charge Size (g) Effective Room Size (m 3 ) Percent Oxygen Concentration in Lower Meter Reasonable Worst-Case Scenario 1 245 41 (1,450 ft 3 ) 21% Reasonable Worst-Case Scenario 2 1,560 20% Threshold Analysis 1: Charge Size 12,800 41 (1,450 ft 3 ) 12% Threshold Analysis 2: Room Size 1,560 5 (180 ft 3 ) 12%
Bold font indicates modeling results.

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. 15 Based on the reasonable worst-case scenario modeli ng, a release of R-443A from window or ducted split-system AC units has an insig nificant impact on the concentration of oxygen in t he air and therefore does not present a significant ri sk of asphyxiation. This modeling does not take int o account any ventilation which is likely to occur, s uch as conditioned airflow, open doors, or even ope nings at the bottom of doors that allow air to flow in an d out, as mentioned above; therefore, the actual asphyxiation risk to person(s) is likely to be even smaller than modeled. For the asphyxiation threshold analyses shown in Ta ble 10, the conditions at which an asphyxiation concern would exist were determined.

• As shown under Threshold Analysis 1, the charge siz e of the window or ducted split



### - system AC unit in a 41 m 3 (1,450 ft 3 ) room would have to be at least 12,800 grams for a sphyxiation to be a concern, which is approximately 8 times greater tha n the maximum modeled charge size (i.e., 1,560 grams).

• Using the charge size of 1,560 grams for ducted spl it-system AC units, as shown under Threshold Analysis 2, the volume of the room would have to be approximately 5 m 3 (180 ft 3 ), or approximately 8 times smaller than the modeled room size 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 R443A in window or split-system AC units poses a sig nificant risk of asphyxiation or impaired coordinat ion

15 Twelve percent oxygen in air is the NOAEL for hypo xia (ICF 1997).March 28, 2016 – Final 13 to personnel, provided systems are installed in app ropriate spaces according to guidelines from the manufacturer and the SDS for R-443A.



### 9. END-USE EXPOSURE ASSESSMENT This section presents estimates of potential end-us er exposures to R-443A in the event of a catastroph ic release from the proposed substitute’s use in windo w and ducted split-system AC units. An end-use exposure analysis was performed to examine potentia l catastrophic releases of R-443A under the reasonable worst-case scenario 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 duc ted split-system AC unit were examined. As discusse d in Section 5, the full charge of the unit is assume d to be emitted over the course of 1 minute. The an alysis was undertaken to determine the 30-minute TWA expos ures of R-443A components, which were then compared to the standard toxicity limits presented in Table 7 to assess the risk to end-users. The est imated TWA values are fairly conservative as the analysis reflects minimal airflow (i.e., natural ventilation ), but does not consider mechanical ventilation such as fa ns, conditioned airflow (either heated or cooled) a nd other variables that would reduce the levels to whi ch individuals would be exposed. Because propylene is present in larger concentrations and because it has a lower exposure limit than other R-443A component s, Table 11 only displays exposures for propylene, the component with greater potential concerns. Modelin g results are presented in Table 11.

Table 11. End-Use Exposure Assessment of R-443A Pro pylene Component a

Equipment Scenario Charge Size (g) b Effective Room

Size (m 3 ) Air

Exchange Rate (ACH) Vertical

Concentration Gradient 30

- minute

TWA EndUse Exposure (ppm) c, d

Window Units Reasonable Worst

- Case Scenario 1a 160 41 (1,450 ft 3 ) 0.67 Yes 2,380

Reasonable Worst

- Case Scenario 1b 245 3,650 Reasonable Worst

- Case Scenario 1c 160 41 (1,450 ft 3 ) No 990 Reasonable Worst

- Case Scenario 1d 245 1,520

Ducted SplitSystems Reasonable Worst

- Case Scenario 2a 416 41 (1,450 ft 3 ) 0.67 Yes 3,440

Reasonable Worst

- Case Scenario 2b 1,560 12,900 Reasonable Worst

- Case Scenario 2c 416 41 (1,450 ft 3 ) No 2,580 Reasonable Worst

- Case Scenario 2d 1,560 9,680

Window Units Threshold Analysis 1a: Charge Size 100 41 (1,450 ft 3 ) 0.67 Yes

1,500

Threshold Analysis 1 b : Room Size 245 110 (4,020 ft 3 ) 0. 11 Threshold Analysis 1c : ACH 245 41 (1,450 ft 3 ) 5 Yes
Ducted SplitSystems Threshold Analysis 2 a : Charge Size 180 41 (1,450 ft 3 ) 0.67 Yes

Threshold Analysis 2 b : Room Size 1,560 400 (14,200 ft 3 ) 0. 11 Threshold Analysis 2c : ACH 1,560 41 (1,450 ft 3 ) 20 Yes Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling a ssumption options.
b An R-443A unit with a charge size of 160 grams cont ains 88 grams of propylene; 245 grams of R-443A con tains 135 grams of propylene; 416 grams of R-443A contains 229 grams of propylene; an d 1,560 grams of R-443A contains 858 grams of propy lene.

c EPA-derived STEL (see Table 7)
d Values provided in this column refer to the concen tration in the lower 1 meter of the room for window units and 1.8 meters for split-systems, which presents the most conservative risk as 95 per cent of the leaked refrigerant is present in this s pace.March 28, 2016 – Final 14 Under the reasonable worst-case scenario described in Section 5 for window and ducted split-system AC units, the anticipated 30-minute TWA exposures of R -443A following catastrophic releases of window and ducted split-system AC units were modeled with two air exchange rates, 0.11 ACH and 0.67 ACH. According to the results in Table 11, the 30-minute STEL for propylene (i.e., 1,500) is likely to be exceeded in all reasonable worst-case scenarios, ex cluding Reasonable Worst-Case Scenario 1c. Reasonable Worst-Case Scenario 1c models the smalle st proposed charge size of 160 grams in the least conservative end-use scenario (i.e., highest ventil ation rate of 0.67 and no vertical concentration gr adient). Because modeled exposures exceed the STEL for propy lene, the largest constituent of R-443A and the component with greater toxicity concern, it is also likely that the RCL for R-443A would be exceeded a t end-use. To further analyze potential risks of exposure duri ng end-use, threshold analyses were conducted to determine the charge size, room size and ventilatio n requirements that ensure that the use of R-443A i n this end-use does not present risk to end-users or servicing technicians. Based on these results, a ro om volume of 41 m 3 (1,450 ft 3 ) should not contain an AC unit with a charge size that exceeds 100 grams, assuming an ACH of 0.67 (Threshold Analysis 1a in T able 11). The analysis also indicates a split-syste m AC unit with a charge size of 1,560 grams should no t be installed in a room of effective volume less t han 400 m 3 (14,200 ft 3 ), assuming an ACH of 0.67 (Threshold Analysis 2b i n Table 11). In addition, although the submitter indicates a complete loss of refriger ant is unlikely due to the presence of a safety val ve, a release of 40 percent of the 245-gram refrigerant c harge for window units, 60 percent of the 290-gram refrigerant charge for split-systems covered by UL, and only 11 percent of the 1,560-gram refrigerant charge for ducted split-systems could lead to an ex posure concern (see Threshold Analyses 1a and 2a). In order for toxicity risk to not be of concern, th e results of the threshold analyses indicate R-443A would have to be installed under room size and ventilatio n conditions that are not typical of residential ro oms (see Table 11). For instance, the recommended air exchan ge rate for R-443A in the modeled room size is approximately 45 times greater than the typical air exchange rate for residential rooms (i.e., 0.45 AC H) (EPA 1997). Because R-443A presents a significant t oxicity risk at end-use for both the submitter’s ty pical charge sizes and the charge sizes recommended by UL 484 (i.e., 160 and 290 grams), R-443A is not recommended for SNAP approval in residential and li ght commercial AC and heat pumps, specifically window AC units, split-system AC units, residential heat pumps, and portable AC units.



### 10. OCCUPATIONAL EXPOSURE ASSESSMENT This section assesses potential exposures to worker s during manufacture, installation and servicing, a nd disposal of R-443A window and split-system AC units . To determine whether the use of the proposed substitute in window and ducted split-system AC uni ts poses an unacceptable toxicity risk to workers during servicing and disposal, occupational exposur e modeling was performed using a box-model approach. For a detailed description of the method ology used for this screening assessment, the reade r is referred to the occupational exposure and hazard an alysis described in Chapter 5 of the Background Document. 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 incidentalMarch 28, 2016 – Final 15 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. Similar to the end-use exposure assessment, Tables 12 and 13 only present exposures for propylene, the component with the greater potential concern. 10.1 Occupational Exposure at Manufacture of Substi tute R-443A is produced in the United States. During man ufacture of R-443A, the SDS should be referenced and proper engineering controls and PPE used.

The submitter indicates R-443A is manufactured in c losed systems constructed for safety and eliminatio n of environmental releases and worker exposure (A.S. Trust & Holdings 2013). Therefore, R-443A is not expected to pose a risk to workers during manufactu re or blending when the engineering controls and PP E recommendations referenced in the SDS for R-443A ar e followed. Release points/exposure in chemical manufacturing would typically be where temporary li nes are connected or disconnected (i.e., filling of portable cylinders and portable bulk containers). R efrigerant quality control testing may result in re lease 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 R-443A, there is no significant risk to workers during the manufacture of R-443A. 10.2 Occupational Exposure at Charging and Servicin g Window and ducted split-system AC units would typic ally be charged by the Original Equipment Manufacturer (OEM). During OEM system manufacture ( i.e., charging at OEM location), points of release for charging and servicing these leak-tight systems would be from connection/disconnection of temporar y lines for charging and recovery equipment. Window and ducted split-system AC units are expecte d to be serviced rarely, since this type of equipme nt is hermetically sealed. Generally, in the United St ates, these units are replaced rather than serviced if the charge leaks. Nevertheless, the potential occupatio nal exposure during servicing was analyzed. The possibility of a release during installation was al so considered. The maximum 30-minute TWA exposure for each component in R-443A was estimated for serv icing window and ducted split-system AC units charged with 245 grams or 1,560 grams of R-443A. Installation and servicing activities for R-443A wi ndow and ducted split-system AC units are not expec ted to result in significant worker exposure when certi fied technicians follow the procedures outlined in the R443A SDS and maintenance manual, undergo proper tra ining, and wear appropriate PPE (e.g., gloves and safety glasses). Nevertheless, the potential occupa tional exposure during servicing was analyzed. The maximum 30-minute TWA exposures for propylene, the R-443A constituent with greater potential concern, were estimated and compared to the STEL (s ee Table 12). The modeling results indicate that th e maximum anticipated occupational exposure concentra tions do not exceed the STEL for propylene (i.e., 1,500 ppm).March 28, 2016 – Final 16 Table 12. Occupational Risk Assessment at Servicing a

R-443A Component 30-minute TWA

Occupational Exposure (ppm) 30-minute TWA

Occupational Exposure (ppm) 30-min Short

Term Exposure Limits (ppm) Charge Size: 245 grams Charge Size: 1,560 grams Propylene 1 7 1,500 b 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 EPA-derived STEL (see Table 7) 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 window and split-system AC units containing R-443A presents a significant concern to workers. 10.3 Occupational Exposure at Disposal Disposal of R-443A window and split-system AC units is expected to occur with limited frequency (up to approximately ten disposal events per day) at dispo sal facilities and with limited duration of exposur e to the installed refrigerant. Typically, potential exp osures to the refrigerant during recovery and dispo sal are expected to occur during activities related to deco mmissioning refrigeration systems (e.g., attaching of hoses associated with draining or otherwise dischar ging of refrigerant from the refrigeration units in to cylinders) and would be similar to those during ser vicing, because similar refrigerant charging and/or recovery equipment would be used (see Section 10.2 and Table 12 for information and modeling results related to exposure during servicing activities). S uch activities and related exposure is anticipated to occur within 15-30 minutes (per event/day). Table 13 displays the maximum estimated 8-hour TWA occupational exposure levels for R-443A component, propylene, during disposal. To model a w orst-case scenario, it was assumed that of the 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 complete 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 R-443A’s component with the gre atest potential concern, occupational exposure to t he proposed substitute during disposal is not consider ed a toxicity risk. Further, estimated exposures we re derived using conservative assumptions (e.g., no ve ntilation) and represent a worst-case scenario with a low probability of occurrence. These types of syste ms are typically disposed of by trained personnel u sing proper industrial hygiene techniques while wearing PPE. Table 13. Occupational Risk Assessment at Disposal a

R-443A Component 8-Hour TWA Occupational

Exposure (ppm) 8-Hour TWA Occupational Exposure (ppm) 8-Hour Long Term Exposure Limits (ppm) Charge Size: 245 grams Charge Size: 1,560 grams Propylene 54 3 1 0 5 00 b Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling a ssumption options.
b OSHA PEL

c ACGIH TLVMarch 28, 2016 – Final 17 

### 11. GENERAL POPULATION EXPOSURE ASSESSMENT This section presents an assessment of potential ri sks to the general population posed by the use of R -443A in residential and light commercial AC and heat pum ps. The general population is defined in this risk screen as non-personnel who are subject to exposure of the proposed substitute near industrial facilit ies, including manufacturing or equipment production fac tories, equipment operating sites (for on-site installation or disposal activities only), or recyc ling centers, rather than consumers at end-use. R-443A 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 r esidential and light commercial AC and heat pumps. The proposed substitute will be manufactured in a close d process and is proposed for use in closed systems ; thus, significant releases are not anticipated. At room temperature, R-443A is a gas; therefore, relea ses to ground or surface water are not anticipated, as R-4 43A is anticipated to dissipate into the atmosphere upon release to outside air (i.e., because natural venti lation rates would be higher and there is no enclos ed space to maintain a high concentration of R-443A). Should air releases during manufacturing operations occur

, engineering controls should be used (e.g., carbon a bsorption scrubbers) to collect R-443A and prevent the release of the chemical to the atmosphere. EPA beli eves that by using proper engineering controls and by following disposal and containment recommendations outlined in the proposed substitute’s SDS and this risk screen, exposure to R-443A is not expected to pose a significant toxicity risk to the general population.

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