### May 30, 2014 -- Final 1 

## Significant New **Alternatives Policy Pr ogram**  **Refrigeration and Air Conditioning Sector**  **Risk Screen on Substitutes for**  **HCFC -**  **22 in**  **Residential and Light Commercial Air Conditioning and Heat Pumps**  **Substitute: R -**  **441A This risk screen is restricted to**  **residential and light commercial window air conditioner applications and other self**  **- contained room air conditioners meeting the requirements of UL 484:** 

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

### 1. **INTRODUCTION** Ozone - depleting substances (ODS) are being phased out of production in response to a series of diplomatic and legislative efforts that have taken place over the past two decades, including the Montreal Protocol and the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection Agency (EPA), as authorized by Section 612 of the CAAA, administers the Significant New Alternatives Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific end -uses based o n assessment of their health and environmental impacts. EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of potential human health and environmental risks posed by the substitute in specific applicati ons. EPA has already screened a large number of substitutes in many end -use applications within all of the major ODS using sectors including: refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire suppression, adhesives, coatin gs and inks, and sterilization. The results of these risk screens are presented in a series of Background Documents that are available in EPA's docket. The purpose of this risk screen is to supplement EPA’s Background Document on the refrigeration and air conditioning sector (EPA 1994) (hereinafter referred to as the Background Document) . This risk screen evaluates the potential use of R- 441A as a substitute for HCFC - 22 in the residential and light commercial air conditioning (AC) and heat pump end -use that meets the requirement of Underwriters Laboratory (UL) Standard 484: Room Air Conditioners , specifically in window AC units , packaged terminal AC (PTAC), packaged terminal heat pumps ( PTHP ) , and portable AC units . Table 1 details the composition of the proposed substitute. **Table 1**  **. Composition of R -**  **441A**

**Constituent Chemical Formula**  **CAS Number Concentration**  **(Weight Percent) a**  Propane C 3 H 8 74 - 98 - 6 55% n - Butane C 4 H 10 106 - 97 - 8 36% Isobutane C 4 H 10 75 - 28 - 5 6% Ethane C 6 H 14 74 - 84 - 0 3% a There are no impurities of toxicological or ecological significance anticipated for this formulation. Isomers of hydrocarbons present in formulation mixture will exist, but are not considered to be an impurity, contaminant or byproduct.

### May 30, 2014 -- Final 2 Section 2 of this report summarizes the results of the risk screen for the proposed substitute blend listed in 

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**erence source not found.** . The remainder of the report is organized into th e 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 Assessment  Section 9 : End -Use Exposure Assessment  Section 10 : Occupational Exposure Assessment  Section 11 : General Population Exposure Assessment  Section 12 : References 

### 2. **SUMMARY OF RESULTS** R - 441A is recommended for SNAP approval fo r residential and light commercial room AC units that comply with Underwriters Laboratory ( UL ) S tandard 484: Room Air Conditi o ners , specifically window AC units, packaged terminal AC (PTAC), packaged terminal heat pumps ( PTHP ) , and portable AC units . EPA's risk screen indicates that the use of the proposed substitute and its constituents will be less harmful to the atmosphere than the continued use of HCFC - 22 as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime . No significant asphyxiation risks to consumers or toxicity risks to workers, consumers, or the general population are expected. Three of the four components of R- 441A are subject to volatile organic compound (VOC) regulations under the CAA (40 CFR 51. 1 00 (s) ). Based on analysis of potential impacts of hydrocarbon refrigerant emissions on ground level ozone concentrations , VOC emissions from the use of R- 441A in window air conditioners are not anticipated to contribute significantly to ground leve l ozone concentrations in the United States . Itis expected that procedures identified in the MSDS for R- 441A and good manufacturing practices will be adhered to, and that the appropriate safety and personal protective equipment (PPE) (e.g., protective glo ves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in case of leakage or insufficient ventilation) consistent with Occupational Safety & Health Administration ( OSHA ) guidelines will be used during manufacture, instal lation, servicing, and disposal of room AC systems using R- 441A . Because units are to be installed in locations with adequate space or ventilation in accordance with the AC maintenance manual for R- 441A window AC units , as discussed in greater detail in Se ction 9, significant toxicity or flammability risk to consume rs is also unlikely. Additional safeguards , including specified refrigerant concentration limits (RCL) of R- 441A components , are also provided by adherence to industry standards including American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 15 , 1 34, 2 and 62, 3 and Underwriters Laboratories ( UL ) Standard 484. 4

1 Safety Standard for Refrigeration Systems ASHRAE Standard 15 establishes safeguards for life, limb, health, and property and prescribes safety requirements. 2 Designation and Safety Classification of Refrigerants ASHRAE Standard 34 is establishes a uniform system for assigning reference numbers, safety classifications, and refrigerant concentration limits to refrigerants. Safety classifications base d on t oxicity and flammability data are included. 3 Ventilation for Acceptable Indoor Air Quality ASHRAE Standard 62 establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. 4 UL 484 Standard for Safety: Room Air Conditioners establishes safety requirements for room air conditioners that are designed to provide delivery of conditioned air to an enclosed space, room, or zone.

### May 30, 2014 -- Final 3 **3. ATMOSPHERIC**  **ASSESSMENT** This section presents an assessment of the potential risks to the atmosphere posed by the use of R- 441A in window AC units . The ozone depletion potential (ODP), global warming potential (GWP), and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 2. The proposed substitute is substantially less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime compared to HCFC - 22 . In addition, R- 441A also has lower climate impact and a shorter atmospheric lifetime than those predicted for other substitutes examined in the Background Document , as well as a commonly utilized substitute, R - 410A. Thus, EPA believes that use of R- 441A would result in substantially less harm to the climate and ozone layer than the continued use of ODS and commonly used ODS substitutes, such as HCFC - 22 and R- 410A. **Table 2**  **. Atmospheric Impacts of R** **- 441A**  **Components Compared to HCFC**  **- 22**  **and R -**  **410A Refrigerant**  **Ozone Depleting Potential (**  **ODP )**  **Global Warming Potential**

**– 100 year**  **( GWP**  **) a**  **Atmospheric Lifetime in Years (**  **ALT )**  Propane 0 3.3 0.03 b n - Butane 0 4.0 0.018 c Isobutane 0 ~4 0.016 b Ethane 0 5.5 0.21 c HCFC - 22 0.13 b 1,810 12 a R - 410Ad 0 2,088 NAe NA = not applicable a IPCC 4 th Assessment Report (Forster et al. 2007) b WMO (2011) c IPCC/TEAP (2005) d R - 410A is a blend of 50% HFC - 32 and 50% HFC - 125. e Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HCFC - 22 is 12 years and the ALT for CFC - 115 is 1,700 years (IPCC 4 th Assessment Report [Forster et al. 2007]). 

### 4. **VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS** Propane, isobutane and n -butane are regulated as VOCs under the CAA, while ethane is exempted (40 CFR 51.100 [s]). Through regulations and standard industry practices, VOC emissions should be controlled. A separate analysis was prepared by EPA (2014) to evaluate the potential impact of the use of hydrocarbon refrigerants on ground - level ozone concentrations in the Unit ed States. The analysis estimated refrigerant emissions from refrigeration and air conditioning equipment, which were assumed to contain propylene, isobutane, and /or propane 5 under different scenarios. Under the most conservative scenario it was assumed that propylene was used in all refrigeration and air conditioning equipment. In the most realistic scenario, all three hydrocarbons were assumed to be used in certain types of refrigeration and air conditioning equipment , depending on the proposed use of e ach alternative under submissions received by the SNAP Program at the time of the analysis. End -uses in the evaluation included residential AC units (e.g., window units, PTAC/PTHP) , for which SNAP hydrocarbon applications have been received and /or UL Standards covering flammable refrigerants exist. Th e hydrocarbon emissions from these scenarios were estimated based on U.S. EPA’s Vintaging Model, and their potential contributions to ozone concentrations were assessed using U.S. EPA’s Community Multi scale Air Quality (CMAQ) model. CMAQ modeling was performed for April through the end 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,

5 EP A uses the maximum incremental reactivity (MIR) of ethane (0.28 g - O 3 /g - substance) as the threshold for determining whether a compound has negligible reactivity. Propylene (MIR = 11.57), isobutane (MIR = 1.34), and propane (MIR 0.56) are all considered to be reactive compounds and are therefore subject to VOC regulations.

### May 30, 2014 -- Final 4 due to their distinctive geographic setting and chronic high levels of ground level ozone, and then scaled for national emission estimates. The results of the CMAQ modeling indicated that under the most realistic scenario, hydrocarbon refrigerants could potentially increase the maximum 8 -hour average ground level ozone by less than 0.15 ppb in Los Angeles, the city with the greatest ozone problem. Th is is roughly 0.2 percent of the curre nt National Ambient Air Quality Standard (NAAQS) for ozone of 75 ppb. In 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 maxi mum increase of the 8 - hour average as high as 6.61 ppb ozone , or an increase of up to 9 percent of the NAAQS . However, this upper bound level of increase is not likely, as most ozone nonattainment areas are not VOC - limited (i.e., the formation of ozone in these ar eas are not by 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 may be used in the refrigeration and air conditioning end -uses . Based on the r esults of this analysis, VOC emissions from the use of R - 441A in window AC units are not anticipated to contribute significantly to ground level ozone concentrations in the United States . 

### 5 **. DISCUSSION OF END**  **- USE SCENARIOS MODELED**  R - 441A is proposed for use in residential and light commercial room AC units. The remainder of this risk screen assesses the risk of window AC units . To represent a reasonable worst - case scenario , it was assumed that the full charge of the window AC unit i s emitted over the course of one minute into a bedroom , where it is located . Because window AC units can be installed in a wide range of locations with varying room volumes, the analysis in this risk screen conservatively assumes that the window air condit ioner is located in a bedroom with a volume of 41 m3 (1,450 ft 3 ) . Under EPA’s proposed charge size limits, which correspond to those found in UL 484, the maximum refrigerant charge allowed for R441A window AC units installed in a room of 41m3 (1,450 ft 3 ) is 19 5 grams. 6 However, the submission states that R- 441A window AC units will have a typical charge size of 125 grams . Furthermore, UL Standard 484 indicates that the maximum charge size of a window AC unit containing a flammable refrigerant is 1,000 gr ams. Therefore, this risk screen evaluates the risks associated with all three charge sizes. This risk screen evaluates a bedroom with air exchange rate s of 0. 11 ACH and 0.67 ACH . The EPA Exposure Factors Handbook (1997) states that 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 AC units than newer homes. B ased on data of AC use in U.S. homes by year of construction, 27 percent of homes using AC equipment use window AC units, while the remaining use central air conditioning equipment (EIA 2013). On average, 38 percent of homes built before 1990 use window AC units in comparison to the average of 9 percent of homes built after 1990. Air exchange rates are expected to be greater in older homes that are typically built with loose construction practices (e.g., no or inadequate effort to seal structural panels, corners, cracks, joints, and penetrations; window and door assemblies are not rated). Additionally, if a home uses window AC units, EPA does not expect that there is any significant mechanical ventilation present in the home. During the cooling season (May t o September), air changes per hour in spaces with a floor area of 900 square feet or less are reported 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 exchange rates , 0. 11 ACH and 0.67 ACH , in order to account for installation of units in homes with different construction practices, for all three charge sizes (125 grams, 19 5 grams, and 1,000 grams). Itis further assumed that an individual is present at the start of the leak and remains in the room until the

6 Under EPA’s proposed limits, for a conservative room of 41m3 , the appropriate cooling capacity would be approximately 6, 5 00 BTU/hr, corresponding to an ass ociated charge size limit of 195 grams.

### May 30, 2014 -- Final 5 charge is completely released. UL 484 assumes that window AC units and their c ompressors are installed at a height of 1 meter above the ground. Based on this location and because R- 441A is denser than air (specific gravity of R- 441A relative to air is 1.67 [air = 1]) , this risk screen assumes that a vertical concentration gradient of R- 441A will occur. In order to simulate the vertical concentration gradient, it is assumed that 95 percent of the leaked refrigerant mixes evenly into the lower 1 meter of the room, and the rest of the refrigerant mixes evenly in the remaining volume (Kataoka 2000 ). Modeling of the lower 1 meter of the room is consistent with the p ossibility that, in a bedroom scenario, individuals may be lying close to the floor. Table 3 details the assumptions used in the models throughout this risk screen (i.e., in Sections 7, 8, and 9). **Table 3**  **. End**  **- Use**  **Scenario Model Assumptions** 

**Parameter Assumption**  **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 Charge Size (g) 125 d ; 19 5 e ; 1,000 f Length of Release (minutes) 1 Vertical Concentration Gradient Yes a Background Document (EPA 1994) b Tight construction home (ACCA 2006) c Loose construction home (ACCA 2006) d Maximum charge size for a window AC under EPA’s proposed use conditions., based on a room size of 41 m 3 , and capacity of 65 00 BTU/hr . e Typical charge size (A .S. Trust & Holdings, Inc. 201 2 ). f Maximum charge size for a window AC unit under UL 484. 

### 6 **. POTENTIAL HEALTH EFFECTS**  To assess potential health risks from exposure to the proposed substitute in window AC units, EPA identified the relevant toxicity threshold values for comparison to modeled exposure concentrations for different scenarios for each constituent of R- 441A. To protect consumers from the potential dangers of a catastrophic leak from the refrigeration unit, ASHRAE Standard 34 determined refrigerant concentration limits (RCLs) for the components of R- 441A which are intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during refrigerant us e (ASHRAE 2010b). ASHRAE Standard 15 implements the aforementioned standard, requiring that “the concentration of refrigerant in an enclosed space following a complete discharge of a high -probability system shall not exceed the RCL” to ensure that there is not a significant risk of toxicity, asphyxiation, and flammability (ASHRAE 2010a). As such, this risk screen references the RCL of the R- 441A components in addition to the lower flammability limit, hypoxia NOAEL, and exposure limits, as an additional, con servative limit to ensure that significant flammability, asphyxiation, and end -use exposure risks , respectively, do not occur. 

### For the occupational exposure anal ys is, potential risks from chronic and acute worker exposure were evaluated b y comparing exposure concentrations to available occupational exposure limits. Potential risks of chronic worker exposure were evaluated using workplace guidance levels (WGL) . Risks from potential short - term consumer exposures were evaluated by comparing exposure con centrations to emergency guidance levels (EGL). Potential short - term, end -use exposures are compared to an established short - term exposure limit (STEL), acute exposure guideline level (AEGL), or emergency response planning guideline (ERPG); in the absence of these limits, an excursion limit,

### May 30, 2014 -- Final 6 calculated according to the methodology described in ACGIH (2004), is applied. 7 When evaluating the toxicity of R- 441A , the cumulative effects and additivity of toxicities of short - chain aliphatic hydrocarbons are not c onsidered to be a concern. ACGIH and OSHA do not consider these cumulative risks. Furthermore, a recent study evaluated alkane gases (ethane, propane, n -butane, and isobutane) in combined repeated exposure studies with reproduction/development toxicity scr eening tests. No significant effects on systemic toxicity or neurotoxicity were found at concentrations from 9,000 to 16,000 ppm, and no significant effects on developmental or reproductive toxicity were found at the highest concentrations tested (McKee RH et. al. 2013). Furthermore, the components of R- 441A do not share an end -point of concern. Table 4 lists the relevant toxicity limits of R- 441A components, and is followed by Table 5 , which provides an explanation of each toxicity limit. EPA’s approach for identifying or developing these values is discussed in Chapter 3 of the Background Document. **Table 4**  **. Exposure Limits**  **of R** **- 441A Components** 

a OSHA PEL available at: http://www.cdc.gov/Niosh/npg/npgd0524.html b ACGIH TLV for aliphatic hydrocarbon gases: alkane (C 1 - C 4 ) is 1 , 000 ppm TWA (ACGIH 2012) c An IDLH of 2,100 ppm has been established for propane. However, NIOSH (1996) states that "[b]ased on acute inhalation toxicity data in humans (ACGIH 1991; Braker 1980), a value much greater than 10,000 ppm would have been appropriate. However, the revised IDLH for propane is 2,100 pp m based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 2.1%)." Therefore, as this IDLH v alue is based on flammability concerns and not toxicity concerns, it is not used in the evaluation of toxicity risks in this risk s creen. d AEGL - 1 available at: http://www.epa.gov/opptintr/aegl/pubs/tsd96.pdf e AEGL - 1 available at: http://www.epa.gov/opptintr/aegl/pubs/tsd102.pdf f Because n - Butane and isobutane have the same molecular formula, EGL for isobutane is conservatively assumed 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 ingredient (21 CFR 184.1165). No toxic effects reported below 18,000 ppm.” g ASHRAE (20 10b ) h Calculated as three times the TLV - TWA (ACGIH 2004). i DOE (2008) **Table 5**  **. Explanation of Exposure Limit** **- Related Terminology**  **a**

7 I t should be noted that this risk screen evaluates both short - term occupational and end -use (i.e., non - occupational) exposure to ethane by comparison to the excursion limit, which is typically used to evaluate short - term occupational exposure. EPA believes, however, that in the absence of an AEGL, STEL, or ERPG, the excursion limit provides a reasonable proxy. Notably, the ACGIH methodology (i.e., a calculation of three times the TLV - TWA) has also been used by DOE (2008) to develop temporary emergency exposure limit s (TEEL) for ethane ( 3,500 mg/m3 or 2,900 ppm 15 - min TWA), which apply to the general population. **R -**  **441A Component**  **8 -**  **hr WGL (Long**  **- term**  **Exposure) ppm**  **30 -**  **min EGL (Short**  **- term**  **Exposure) ppm**  **Refriger ant Concentration**  **Limit (R**  **CL )**  **ppm** Propane 1,000 a

(OSHA PEL) 10,000 c , d (10 min AEGL - 1) 6,900 d 30 min AEGL - 1) 5,300 g n - Butane 1,000 b (ACGIH TLV) 6,900 e (30 min AEGL - 1) 4,000 g Isobutane 1,000 b (ACGIH TLV) 6,900 f 4,000 g Ethane 1,000 b (ACGIH TLV) 3,000 h (30 min ACGIH Excursion Limit) 2,900 i (15 - min TEEL - 1) 7,000 g

**Organization Definition**  OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Health ACGIH American Conference of Governmental Industrial Hygienists AIHA American Industrial Hygiene Association **Exposure Limit Definition**  **Explanation**

### May 30, 2014 -- Final 7 **Short -**  **Term Exposure** STEL Short - Term Exposure Limit A 15 - minute TWA exposure that should not be exceeded at any time during a workday, even if the 8 - hour TWA is within the TLV– TWA, set by ACGIH. AEGL b,c Acute Exposure Guideline Level 1 AEGL - 1 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomat ic nonsensory effects, set by EPA. However, the effects are not disabling and are transient and reversible upon cessation of exposure. Acute Exposure Guideline Level 2 AEGL - 2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long - lasting adverse health effects or an impaired ability to escape, set by EPA. Acute Exposure Guideline Level 3 AEGL - 3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life threatening health effects or death, set by EPA.

ERPG Emergen cy Response Planning

Guideline 1 T he maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing other than mild transient health effects or perceiving a clea rly defined, objectionable odor according to AIHA. Emergency Response Planning Guideline 2 T he maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ab ility to take protective action according to AIHA. Emergency Response Planning Guideline 3 The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing life - threatening health effects according to AIHA. Excursion Limit d Excursion Limit Because methane (and other short - chain alkane gases through butane) does not have a TLV - short - term exposure limit, an excursion limit may be applied. Excursions in worker exposure levels may exceed 3 times the TLV - TWA for no more than a total of 30 minutes during a workday, and under no circumstances 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 without experiencing escape - impairing or irreversible health effects, as indicated by NIOSH.

TEEL e Temporary Emergency Exposure

Limit 1 TEEL - 1 is the maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined, objectionable odor set by DOE. Temporary Emergency Exposure Limit 2 TEEL - 2 is the maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing irreversible or other serious health effects or symptoms that could impair their ab ilities to take protective action set by DOE. Temporary Emergency Exposure Limit 3 TEEL - 3 is the maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing life - threatening health effects set by

### May 30, 2014 -- Final 8 a All information in this table taken from EPA (1994) , except where otherwise noted. b EPA (2012) c A pplicable to emergency exposure periods ranging from 10 minutes to 8 hours. d ACGIH (2004) e Chemical exposure guidelines to use for emergency planning if no AEGL or ERPG is available. TEELs are developed based on conc entration limits or toxicology parameters (DOE 2008). According to the MSDS, exposure to R- 441A may be hazardous if inhalation, s kin contact, or eye contact with R- 441A occurs. The most likely pathway of exposure is through inhalation. R - 441A can cause symptoms of asphyxiation when present in concentrations high enough to significantly lower oxygen concentrations below 19.5 percent by volume, such as headaches, ringing in ears, dizziness, drowsiness, nausea, vomiting, depression of all senses, and also unconsciousness. Under some circumstances of over exposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. In addition, at high concentrations, propane, a major component of the R- 441A blend, can act as a narcotic and cause central nervous system depression, including dizziness, drowsiness, and headaches. If R - 441A is inhaled, person(s) should be immediately remo ved and exposed to fresh air. In accordance with the MSDS, EPA further recommends that if breathing is difficult, person(s) be given oxygen, provided a qualified operator is present, and medical attention be sought. Rescuers should not attempt to retrieve victims of exposure to R- 441A without adequate PPE. At a minimum, a self - contained breathing apparatus (SCBA) should be worn. Exposures of R- 441A to the skin may cause frostbite. In the case of dermal exposure, the MSDS for R- 441A recommends that person(s ) immediately wash the affected area with soap and 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 . Alternatively, if the fingers or hands are frostbitten, warm the affected area by placing it in the armpit; gently exercise the affected part while being warmed, and seek medical attention immediately. Exposures of R- 441A to the eyes could cause eye irritation. In case of ocular exposure, the MSDS for R441A recommends that person(s) immediately flush the eyes, including under the eyelids, with copious amounts of water for 15 minutes. EPA’s review of the human health impacts of this proposed substitute i s contained in the public docket for this decision. The potential health effects of R- 441A can be minimized by following the exposure guidelines and ventilation and PPE recommendations outlined in the MSDS for R- 441A and this risk screen. 

### 7. **FLAMMABILITY ASSESSMENT**  ASHRAE Standard 34 classifies R- 441A a s a Class A3 refrigerant. R- 441A is flammable when its concentration in air is in the range of 2.05 percent to 9.25 percent by volume ( 20,5 00 ppm to 92,500 ppm). In the presence of an ignition source (e.g., static electricity, a spark resulting from a switch malfunction, or a cigarette), an explosion or a fire could occur if the concentration of R- 441A were to exceed the lower flammability limit (LFL) of 20,500 ppm. As such, R- 441A may pose a significant sa fety concern for workers and consumers if it is not handled carefully. The remainder of this section assesses flammability risks and summarizes the recommended measures to ensure safe handling and use of the refrigerant during manufacturing , servicing, and end -use. DOE. **Long -**  **Term Exposure** PEL Permissible Exposure Limit This is an 8 - hour time - weighted average exposure limit set by OSHA. TLV- TWA Threshold Limit Value –Time Weighted Average The TWA concentration for a conventional 8 - hour workday and a 40 - hour workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect according to ACGIH.

### May 30, 2014 -- Final 9 **7 .1**  **Flammability Risks at Manufacture** As indicated by the submitter, the manufacture of R- 441A refrigerant (i.e., formulation mixing) and the charging of R- 441A window air conditioners occurs in a closed system . As a result, releases of R- 441A during manufacturing operations in the presence of an ignition source are not anticipated. All R- 441A storage and transport equipment should be installed with safety devices that minimize the likelihood of catastrophic releases. For example, NFPA 58 Lique fied Petroleum Gas Code (NFPA 20 14 ) for liquefied propane requires the use of overfill protection devices (OPD) on cylinders to minimize the likelihood of leaks. The NPFA 58 Code also contains propane storage and transportation requirements/guidelines. Similar equipment safety and procedural requirements should be developed for R - 441A and other flammable refrigerants. Itis important that all relevant standards be followed during the manufacture of window air conditioners. Itis expected that refrigerants be properly stored and caution used within manufacturing facilities to minimize explosion risk and that workers adhere to the requirements set by OSHA under 29 CFR part 1910. OSHA requirements include proper ventilation and storage practices within man ufacturing facilities to prevent fire and explosion. Good manufacturing practices should be adhered to during the manufacture of equipment containing R - 441A . **7 .2**  **Flammability Risk at Servicing and End -**  **Use** The risk of flammability during servicing and end -use for the reasonable worst - case scenario (see Section 5 ) was investigated for R- 441A. Both servicing and end -use of R - 441A window AC units are expected to take place in the same space (i.e., the place of installation and use). In order to determine the potential flammability risks during servicing or end -use i n case of a catastrophic release of refrigerant, modeled concentrations of R- 441A immediately following the release of refrigerant were compared to the LFL for R - 441A. As demonstrated in

Table , the maximum instantaneous concentration in the lower 1 meter of the room at a charge size of 125 grams would be approximately 3,450ppm, approximately 5,390 ppm for a 195 - gr am charge size, and approximately 27,6 20 ppm for a 1,000 - gram charge size. The 125 - gram charge size indicated by the submitter (Reasonable Worst - Case 1) and the 195 - gram charge size proposed by EPA (Reasonable Worst - Case 2) do not present a significant flammability concern. In contrast, the sc enario using a 1,000 - gram charge size (Reasonable Worst - Case 3) exceeds the proposed substitute’s LFL of 20,500 ppm. However, according to UL 484, a window unit with a charge size of 1,000 grams in not intended for installation in a room with a volume as s mall as that modeled in the worst - case scenario (41 m3 ). The minimum room size for a charge size of 125 grams according to UL 484 is approximately 18 m3 (630 ft 3 ), assuming a 2.4 m ceiling height , and the maximum charge size for a 41 m3 (1,450 ft 3 ) room a ccording to UL 484 is approximately 195 grams. The maximum instantaneous concentration in the upper portion of the room for both modeled charge sizes is much lower, as only 5 percent of the leaked refrigerant is present in this area , and this area has greater volume than the lower 1 meter . EPA is also proposing to

### May 30, 2014 -- Final 10 limit charge sizes that an equipment manufacturer may use for a given cooling capacity. The appropriate cooling capacity for a room of 41 m3 would be approximately 6,500 BTU/hr, with an associated charge limit of 195 grams under EPA’s proposed use conditions. The results of the flammability assessment are presented in Table 6 .

**Table 6**  **. Flammability Assessment a** 

**Scenario Charge Size**  **(g) Effective Room**  **Size (m 3**  **) Maximum Instantaneous** 

**Concentration (ppm)**  b ,c Reasonable Worst - Case 1 125 41 (1,450 ft 3 ) **3,450** Reasonable Worse - Case 2 195 41 (1,450 ft 3 ) **5,390** Reasonable Worst - Case 3 1,000 41 (1,450 ft 3 ) **27,620** Threshold Analysis 1: Charge Size **742** 41 (1,450 ft 3 ) 20,500 Threshold Analysis 2a: Room Size 125 **7 ( 244**  **ft 3**  **)** Threshold Analysis 2b: Room Size 195 **11 (**  **380 ft**  **3 )**  Threshold Analysis 2 c : Room Size 1,000 **55 (**  **1,950 ft**  **3 )**  **Bold** font indicates modeling results. a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b Lower Flammability Limit of R - 441A is equal to 20,500 ppm. c Values provided in these columns refer to the concentration in the lower 1 meter of the room. For the Flammability Threshold analysis shown in Table 6 , the conditions at which a flammability concern would exist (i.e., when the maximum instantaneous concentration in the lower 1 meter of the room equals the LFL for R- 441A) were determi ned. Within the reasonable worst - case room size of 41 m3 (1,450 ft 3 ) , the charge size of the R- 441A window AC would have to be at least 742 grams (see Threshold Analysis 1 in Table 6 ) for a flammability concern to exist, which is approximately 5.9 times larger than the largest size intended by the submitter (i.e., 125 grams) and approximately 3.8 times larger than EPA’s recommended charge size (i.e., 195 grams) for R- 441A window AC units. For window AC units with a charge size of 125 grams (see Threshold Analysis 2a in Table 6 ) the volume of the bedroom would have to be 7 m3 ( 244 ft 3 ) or smaller for a flammability risk to occur. For window AC units with a charge size of 195 - gram s (see Threshold Analysis 2 b in Table 6) the volume of the room would have to b e 11 m3 ( 380 ft 3 ) or smaller for a flammability risk to occur. Using a charge size of 1,000 - gram s for window AC unit s (see Threshold Analysis 2 c in Table 6 ) the volume of the bedroom would have to be 55 m3 ( 1,950 ft 3 ) or smaller for a flammability risk to occur. According to the results of this flammability analysis, the risk of fire is minimal if a window AC unit is installed in a room with volumes in accordance with standards and regulations. As bedrooms can be of smaller sizes, 8 and because persons or furniture in the room may reduce the effective volume of the space, window AC units containing R - 441A should not be installed in rooms with effective volumes less than

8 International Residential Code requires a minimum of 70 ft2 for a habitable room, or 14 m3 (490 ft 3 ) (ICC 2012).

### May 30, 2014 -- Final 11 what UL 484 indicates with respect to charge size , unless additional steps are taken to protect against a flammability risk (e.g., higher ventilation rates). According to UL 484 and assuming a mounting height of 1 meter , R- 441A window AC units with charge sizes of 125 grams , 19 5 grams, and 1,000 grams sh ould not be installed in a room less than 1 7 m3 (6 1 0 ft 3 ) , 41 m3 ( 1,450 ft 3 ) and 1,332 m3 (47,000 ft 3 ) , respectively. In addition, EPA recommends that the ventilation requirements outlined in the MSDS for R441A are followed to mitigate the risk of fire o r explosion during catastrophic leak during end -use or when servicing equipment using R- 441A. Itis also important that only properly trained and certified technicians handle R- 441A. The submitter has provided safety guidelines for handling R - 441A, whic h should be followed. As a further precaution, certification requirements and training programs for technicians that handle R- 441A should be developed using these guidelines. During servicing operations, although considered rare, since this type of equipment is hermetically sealed and is often replaced rather than serviced if the charge leaks , technicians should ensure that proper ventilation is in place through the use of fans (or other mechanical ventilation devices) and portable refrigerant detectors should be used to alert technicians to the presence of flammable gases in the area. The installation of leak prevention devices would further protect against the very limited risk of explosion. When the guidelines recommended by EPA and industry standards including UL 484 are followed, EPA does not believe that use of R- 441A in window AC units presents a significant risk of flammability at servicing or end -use. 

### 8. **ASPHYXIATION ASSESSMENT** The risk of asphyxiation for the reasonable worst - case scenario (see Section 5 ) was investigated for R441A. In this section, risk of asphyxiation is assessed in three ways: 1) modeling the oxygen concentration under the charge size and room size specified in the worst - case scenario, 2) performing a threshold analysis of minimum charge size needed to cause an asphyxiation risk in the room size specified in the worst - case scenario 3) performing a threshold analysis of the maximum room size needed to cause an asphyxiation risk with the charge size specified in the worst - case scenario. This analysis does not consider conditions that are likely to occur that would increase oxygen levels to which individuals would be exposed, such as open doors or windows, fans o perating, conditioned airflow (either heated or cooled), or even openings at the bottom of doors that allow air to flow in and out. As specified in Section 5, this analysis assumes a v ertical concentration gradient. If the proposed substitute passes the sc reening analysis with these restrictive assumptions in place, it can be reasonably assumed that no risks of asphyxiation will be present under real -world conditions. The results of the asphyxiation assessment are summarized in Table 7 below. **Table 7**  **. Asphy xiation Assessment**  **a**

**Scenario Charge Size (g)**  **b Effective Room Size**  **(m 3**  **) Percent Oxygen** 

**Concentration in Lower**  **1 Meter**  Reasonable Worst - Case 1 125 41 (1,450 ft 3 ) **21** Reasonable Worst - Case 2 195 41 (1,450 ft 3 ) **21** Reasonable Worst - Case 3 1,000 41 (1,450 ft 3 ) **21** Threshold Analysis 1: Charge Size **18,520** 41 (1,450 ft 3 ) 12 Threshold Analysis 2a: Room Size 125 **0. 28**  **( 9.8**  **ft 3**  **)** 12 Threshold Analysis 2b: Room Size 195 **0.43 (**  **15.2 ft**  **3 )**  12 Threshold Analysis 2 c : Room Size 1,000 **2.2 (**  **78.2 ft**  **3 )**  12 **Bold font** indicates modeling results. a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. **b** The typical concentration of oxygen in air is considered to be 21 percent (Mackenzie & Mackenzie 1995)

### May 30, 2014 -- Final 12 Under the reasonable, worst - case scenario (see Reasonable Worst - Case 1 and Reasonable Worst - Case 2 in Table 7 ), an asphyx iation risk will not occur, as the oxygen concentration in the room is 21 percent , well above the 12 percent level of concern. 9 The concentration of R- 441A in the air in the lower 1 meter of the room following the release of the maximum charge size of 1,00 0 grams does not exceed 2.3 percent, which has an insignificant impact on the normal concentration of oxygen in air. This modeling does not take into account any ventilation which is likely to occur, such as conditioned airflow, open doors, or even opening s at the bottom of doors that allow air to flow in and out, as mentioned above, therefore, the actual asphyxiation risk to personnel is likely to be even smaller than modeled. For the asphyxiation threshold analyses shown in Table 7 , the conditions at which an asphyxiation concern would exist were determined. Within the reasonable worst - case room size of 41 m3 (1,450 ft 3 ) ( see Threshold Analysis 1 in Table 7 ) the charge size of the R- 441A AC unit would have to be at least 18,520 grams for asphyxiation to be a concern, which is more than 18 times the largest charge size allowed for R- 441A window AC units according to UL 484 (i.e., 1,000 grams) . For asphyxiation to be of concern with a 125 - gram R - 441A window AC unit (see Threshold Analysis 2a in Table 7 ) the volume of the bedroom would have to be 0. 28 m3 ( 9.8 ft 3 ) . Using a 195 - gram window AC unit, as shown under Threshold Analysis 2b, the volume of the room would have to be 0.43 m3 ( 15.2 ft 3 ) or smaller f or asphyxiation to be of concern . Using a 1,000 - gram R - 441A window AC unit (see Threshold Analysis 2 c in Table 7 ) the volume of the bedroom would have to be 2.2 m3 ( 78.2 ft 3 ) for asphyxiation to be a concern, which is significantly smaller than the reasonable worst - case bedroom size (41 m3 [1,450 ft 3 ]). In a ddition, the threshold room volumes at which asphyxiation could occur during a catastrophic leak of a 125 - gram , 195 - gram or 1,000 - gram unit are smaller than the minimum bedroom volume typically found in the U.S. 10 To further protect against an asphyxiatio n risk, end -users should ensure window AC units are installed with an appropriate cooling capacity for the intended cooled space to be consistent with manufacturer recommendations and the guidelines of relevant safety standards (e.g., ASHRAE 15 and UL 484) . Leak prevention, detection, or mitigation devices should be installed and the ventilation requirements outlined in the MSDS for R- 441A should be closely followed. If these guidelines are followed, a catastrophic leak of R- 441A is not anticipated to resul t in a significant asphyxiation risk. 

### 9. **END -**  **USE EXPOSURE ASSESSMENT** This section presents estimates of potential consumer exposures to R- 441A and each of its chemical constituents in window AC units . An exposure analysis was performed to examine potential catastrophic release of the proposed substitute in a bedroom under the reasonable worst - case scenario outlined in Section 5 with a charge size of 125 grams , 195 grams, and 1,000 grams. For the end -use exposure assessment scenario, 30 - minute time -weighted average (TWA) exposures for the constituents of the proposed substitute were calculated using the box model described in the Background Document, which was adapted to estimate concentrations on a minute -by - minute basis. These exposures were then compared to the standard toxicity limit presented in Table 4 to assess the risk to end -users. T he results of the assessment provide both fairly conservative and more realistic TWA values, as the analys e s using both a 0.11 ACH and a 0.67 ACH ventilation rate do not consider opened windows, fans operating, conditioned airflow (either heated or cooled) and other variables that would reduce the levels to which individuals would be exposed . Modeling was perfo rmed for all constituents of R - 441A, however, only the results for propane , which show the end -use exposure levels under the reasonable worst - case scenario in Section 4, are presented in Table 8 . As the primary component of R441A, propane presents the gre atest risk of exceeding the STEL and thus the most conservative

9 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997). 10 The 20 12 International Residential Code requires bedrooms to have a minimum volume of 13.9 m3 (490 ft 3 ) ( ICR ICC 20 12 ).

### May 30, 2014 -- Final 13 assessment. **Table 8**  **. End -**  **Use Exposure Assessment of R**  **- 441A**  **Propane C omponent**  **a Scenario**  **Charge Size (g) Effective**  **Room Size (m**  **3 )**  **Air Exchange**

**Rate (ACH) 30**  **- minute TWA** 

**End -**  **Use Exposure (ppm)**  **b, c**  Reasonable Worst - Case 1 a 125 41 (1,450 ft 3 ) 0. 11 **2,028** Reasonable Worst - Case 1b 0.67 **1,785** Reasonable Worst - Case 2a 195 0. 11 **3, 163**  Reasonable Worst - Case 2b 0.67 **2,7 84**  Reasonable Worst - Case 3a 1,000 0. 11 **16,223** Reasonable Worst - Case 3b 0.67 **14,277** Threshold Analysis 1 a : Charge Size **425** 41 (1,450 ft 3 ) 0. 11

6,900 Threshold Analysis 1b: Charge Size **483** 0.67 Threshold Analysis 2a: Room Size 125 **12 (**  **430 ft**  **3 )**  0. 11 Threshold Analysis 2b: Room Size **11 (**  **370 ft**  **3 )**  0.67 Threshold Analysis 3a: Room Size 195 **1 9**  **( 660**  **ft 3**  **)** 0. 11 Threshold Analysis 3b: Room Size **1 7**  **(5 8**  **0 ft 3**  **)** 0.67 Threshold Analysis 4a: Room Size 1,000 **96 (3,400 ft 3**  **)** 0. 11 Threshold Analysis 4b: Room Size **85 (3,000 ft 3**  **)** 0.67 Threshold Analysis 5a: Air Exchange Rate 125 41 (1,450 ft 3 ) **0** Threshold Analysis 5b: Air Exchange Rate 195 **0** Threshold Analysis 5c: Air Exchange Rate 1,000 **4.4 Bold**  font indicates modeling results . a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b 30 - min AEGL - 1 STEL for propane is 6,900 ppm; See Table 4 for more information c Values provided in this column refer to the concentration in the lower 1 meter of the room, which presents the most conservative risk as s 95 percent of the leaked refrigerant in present in this space. In the reasonable worst - case scenario described in Section 5, catastrophic releases of R- 441A from a window AC unit with charge sizes of 125 grams , 195 grams, and 1,000 grams were modeled with two different air exchange rates, 0.11 ACH and 0.67 ACH . In Reasonable Worst - Case Scenarios 3a and 3b, which model a 1,000 - gram charge size and ventilation rates of 0.11 ACH and 0.67 ACH respectively, the 30 - minute AEGL - 1 for propane of 6,900 ppm is likely to be exceeded (see Table 8). However, the 30 - min TWA exposures in Reasonable Worst - Case Scenarios 3a and 3b do not exceed the AEGL - 2 (17,000 ppm) or the AEGL - 3 (33,000 ppm) for propane. A threshold analysis was performed to determine the charge size, minimum room volume , and ventilation rates where window AC units containing R- 441A could be installed to avoid the STEL for each of the components of R- 441A. Based on this end -use exposure threshold analysis, shown in Table 8, the maximum charge size that should be installed in a room of 41 m 3 (1,450 ft 3 ) volume with 0.11 ACH is 425 grams and 483 grams with 0.67 ACH (see Threshold Analysis 1a and 1b in Table 8) . Additionally, the threshold analysis indicates that window AC units with charge sizes of 1 25 grams, 195 grams, and 1,000 grams should not be installed in rooms smaller than 12 m3 (430 ft 3 ), 1 9 m3 (6 6 0 ft 3 ) , and 96 m3 (3,400 ft 3 ) , respectively, assuming an air ventilation rate of 0.11 ACH. As shown in Table 8, these recommended minimum rooms sizes are smaller if the ventilation rate is increased to 0.67 ACH. Because a window A C units with a charge size of 1,000 grams was modeled in a room size that is much smaller than the size recommended by UL 484 in the reasonable worst - case scenarios, it i s not unexpected that the calculated 30 - minute TWA exposures for th at scenario exceed s the AEGL - 1 for propane. These

### May 30, 2014 -- Final 14 potential exposure exceedances emphasize the importance associated with proper equipment installation , ( i.e. matching charge size with room dimensions ) . To prevent exposure and potential serious side effects during larger releases , EPA proposes the charge size for R- 441A window AC units to require compli ance with UL 484 and with proposed charge sizes based upon cooling capacity in the proposed rule . Smaller accidental releases of the proposed substitute, however, do not pose a significant risk to end-users. Thus, risk of toxicological threat is minimal if a window AC un it is installed in a room with volumes in accordance with standards and regulations and/or in enc losed areas with volumes larger than those determined in the threshold analyses. Furthermore, proper ventilation should be used in accordance with the MSDS for R- 441A . When these conditions are met, accidental catastrophic releases of the proposed substitute would not pose a significant risk to end -users . 

### 10. **OCCUPATIONAL EXPOSURE ASSESSMENT** This section assesses potential exposures to workers during manufactur e, installation, servicing, and disposal of R- 441A in window AC units. As indicated by the submitter, all manufacturing steps will be conducted in closed systems appropriately constructed for safety and elimination of environmental releases and worker exposures. Standard operating procedures and personnel training focus on minimizing such releases and occ upational exposures. As a result, exposure to R- 441A during manufacturing is not anticipated and is not analyzed further. To ensure that use of the proposed substitute in window AC units does not pose an unacceptable risk to workers during servicing and di sposal, occupational exposure modeling was performed using a box model approach. For a detailed description of the methodology used for this screening assessment, the reader is referred the occupational exposure and hazard analysis described in Chapter 5 o f the Background Document. Estimates of refrigerant release per event for various release scenarios and data on number of events were obtained from the Vintaging Model. 11 To determine the estimated level of occupational exposure for a constituent in the pro posed substitute blend, the total anticipated release rate of the refrigerant is multiplied by the weight percent composition of each compound in the blend. For the window AC unit end use, the release per event was conservatively assumed to be 0.4 percent of the equipment charge during installation and servicing and 50 percent of the equipment charge during disposal. 12 Additionally, EPA is proposing to allow intentional venting or release of R- 441A as a refrigerant during installation, servicing, maintenance and disposal from window AC units . If venting does occur, it should be done in a well - ventilated area ( e.g . , outdoors). Therefore, s cenarios in which 100 percent of the equipment charge was released during servicing and disposal were also considered . The release rate per event was multiplied by the number of events estimated to occur over a workday. For equipment servicing, the number of events per workday was assumed to equal the maximum number of units anticipated to be serviced in one day ( i.e., eight u nits [A .S. Trust & Holdings, Inc. 201 2 ]) divided by eight hours per workday. These assumptions result in approximately 1 event per hour. For disposal, it was conservatively assumed that 10 units are disposed during an 8 -hour work day. **10 .1**  **Occupational Exposure at Installation and Servicing**  Window AC units are expected to be serviced rarely, since this type of equipment is hermetically sealed . Generally , in the U.S., these units are replaced rather than serviced if the charge leaks . N evertheless, the p otential occupational exposure for those situations where servicing takes place was analyzed. The 11 ICF International maintains the Vintaging Model for EPA in order to simulate the aggregate impacts of the ODS phase - out on the use and emissions of various ODS and their substitutes over a period of several years across 60 different end - uses. The model tracks the use and emissions of various compounds for the annual vintages of new equipment that enter service in each end - use. The vintage of each type of equipment determines such factors as leak rate, charge size, number of units in operation, and the initial ODS substance that the equipment contained. The service l eak rate and disposal release rate assumptions are consistent with the window AC end -use in Vintaging Model version VM IO file_v4.4_11.6.12. 12 During disposal it is assumed that 100 percent of the refrigerant charge remains in the unit.

### May 30, 2014 -- Final 15 possibility of a release during installation was also considered. The maximum 30 - minute time -weighted average (TWA) exposure for each component in R- 441A was estimated for servicing window AC units charged with 125 grams , 195 grams, and 1,000 grams of R- 441A. As summarized in Table 8, occupational exposure to R- 441A is anticipated to be significantly below the short- term exposure limits (STEL) with either a 125 - gram , 195 - gram or 1,000 - gram charge size and with a 0.4 percent or 100 pe rcent release during installation and servicing. Installation and servicing activities for window ACs using R- 441A are not expected to result in significant worker exposure when certified technicians follow the procedures outlined in the MSDS and maintenan ce manual, undergo proper training, and wear appropriate PPE (e.g., gloves and safety glasses). Adequate ventilation should always be established during any use, handling, or storage of R- 441A. Systems should be installed to ensure leak - free conditions, fo r instance by following procedures of ASHRAE Standard 147 including conducting leak checks once a system is installed (ASHRAE 20 13 b ). In addition, during servicing events, prior to adding refrigerant, all pipes should be inspected for leakages, and repairs should be performed only after all refrigerant has been recovered from the system. By adhering to the safety guidelines mentioned above, and in Section 6 , worker exposure to R- 441A during installation and maintenance is unlikely. **Table 9**  **. Occupational Ris k Assessment at Servicing**  **a R**  **- 441A**  **Component 30**  **- minute TWA** 

**Occupational Exposure (ppm)**  **Charge size: 125 grams 30**  **- minute TWA**  **Occupational Exposure (ppm)**  **Charge size: 195**  **grams 30**  **- minute TWA**  **Occupational Exposure (ppm)**  **Charge size: 1,000 grams**  **30 -**  **min Short**

**Term Exposure Limits (ppm)**  **0.4% Release**  **100%**

**Release 0.4%** 

**Release 100%** 

**Release 0.4%** 

**Release 100%** 

**Release** Propane 0.60 150 0.8 6 21 4 4.8 1,200 6,900 b n - Butane 0.23 57 0.4 4 10 6 1.8 450 6,900 b Isobutane 0.04 9.5 0.07 1 8 0.30 76 6,900 b Ethane 0.07 18 0.07 17 0.60 150 3,000 c a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b AEGL - 1; See Table 4 for more information c ACGIH (2004) **10 .2**  **Occupational Exposure at Disposal** Disposal of the R- 441A window AC unit is expected to occur at disposal facilities with limited duration of exposure to the refrigerant. Potential exposures to the refrigerant during recovery and disposal are expected to occur during activities related to d raining the refrigerant from the refrigeration units into cylinders (e.g., connecting of pipes). Such activities and related exposure is anticipated to occur within 15 - 30 minutes (per event/day). Table 10 displays the maximum estimated 8 -hour TWA occupati onal exposure levels of the R- 441A constituents during disposal. Based on the assumptions described in the beginning of S ection 10 , the modeling indicates that 8 -hour worker exposure concentrations for each of the R- 441A blend components during the 50 perc ent release scenario will at no point exceed the long - term exposure limits of any of the individual components during disposal of R- 441A for window AC units with a charge size of 125 grams , 195 grams, or 1,000 grams . Under the 100 percent release scenario at disposal of the 1,000 - gram window unit, the 8 -hour TWA would be exceeded for the propane component of R- 441A. However, occupational exposure to the proposed substitute during disposal does not represent a true occupational health hazard because the esti mated exposure concentrations of the propane component of R- 441A for all scenarios do not exceed the 8 -hr AEGL - 1 for propane, which is 5,500 ppm . Furthermore, these estimated exposures were derived using conservative assumptions (e.g., no ventilation or us e of PPE assumed), and represent a reasonable worst - case scenario with a low probability of occurrence. These types of systems are typically disposed of by trained personnel using proper industrial hygiene techniques.

### May 30, 2014 -- Final 16 **Table 10**  **. Occupational Risk Assessment at Disposal**  **a R**  **- 441A**  **Component 8**  **- Hour TWA** 

**Occupational Exposure (ppm)**  **Charge size: 125 grams 8**  **- Hour TWA**  **Occupational Exposure (ppm)**  **Charge size: 195**  **grams 8**  **- Hour TWA**  **Occupational Exposure (ppm)**  **Charge size: 1,000 grams**  **8 -**  **Hour Long Term**

**Exposure L imits**  **(ppm) 50%**  **Release 100%** 

**Release 50%** 

**Release 100%** 

**Release 50%** 

**Release 100%** 

**Release** Propane 130 270 190 37 9 1,060 2,100 1,000 b n - Butane 50 100 9 4 18 8 400 800 1,000 c Isobutane 8.4 17 1 6 31 67 130 1,000 c Ethane 16 32 15 30 130 260 1,000 c a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b OSHA PEL c ACGIH TLV Because anticipated occupational exposures could potentially exceed the exposure limits for each of the components of R- 441A during disposal of 1,000 - gram window AC units without recovery, the recommendations for proper engineering controls and PPE in the MSDS for R- 441A should be followed. Adequate ventilation should always be established during any use, handling, or storage of R - 441A. Engineering controls should include vapor - in air detection systems and local exhaust ventilation during use of R- 441A to prevent dispersion throughout the work place. In addition, an eye wash and safety shower should be near the manufacturing facility and locations where R- 441A is stored and ready for use. In general, use of PPE is recommended, such as splash goggles, mechanically -resistance gloves when handling cylinders and chemically -resistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). SCBA and fire retardant protective clothing should be worn in case of an accidental release or spill (A.S. Trust & Holdings, Inc. 201 2 ). EPA believes that if proper handling and disposal guidelines are followed in accordance with good industrial hygiene and manufacturing practices and the MSDS for R- 441A, there is no significant risk to workers during the manufacturing, installation, servicing, and disposal of R - 441A in window AC units. 

### 11 **. GENERAL POPU**  **LATION EXPOSURE ASSESSMENT**  R - 441A is not expected to cause a concern for human health in the general population when used as a refrigerant in window AC units. At room temperature, R - 441A is a gas and, therefore, releases to ground or surface water are not anticipated , as R- 441A is anticipated to dissipate into the atmosphere upon release to outside air (i.e., because natural ventilation rates would be higher and there is no enclosed space to keep propane concentrated) . Should air releases during manufacturi ng operations occur, including filling of AC units, engineering controls could be used (e.g., carbon absorption units or scrubbers) to collect R- 441A and prevent the release of R- 441A to the atmosphere. EPA believes that by using proper engineering control s and by following disposal and containment recommendations outlined in the proposed substitute’s MSDS, exposure to R - 441A is not expected to pose a significant toxicity risk to the general population.

### May 30, 2014 -- Final 17 **12 .**  **REFERENCES** Air Conditioning Contractors of America (ACCA). 2006. Manual J Residential Load Calculation Eighth Edition . ACGIH. 2004. The Documentation of the Threshold Limit Values and Biological Exposure Indices. American Conference of Governmental Industrial Hygienists. Available at: www.acgih.org. ACGIH. 2005. Guide to Occupational Exposure Values. American Conference of Governmental Industrial Hygienists. ANSI/ASHRAE. 2010 a . Standard 15: Safety Standard for Refrigeration Systems. American Society of Heating, Refrigerating and Air - Conditioning Engineers, Inc. ANSI/ASHRAE. 2010 b . Standard 34: Designation and Safety Classification of Refrigerants. American Society of Heating, Refrigerating and Air - Conditioning Engineers, Inc. ANSI/ASHRAE. 2013 a . Standard 62: Ventilation for Accep table Indoor Air Quality. American Society of Heating, Refrigerating and Air - Conditioning Engineers, Inc. ANSI/ASHRAE. 2013 b . Standard 147: Reducing the Release of Halogenated Refrigerants from Refrigerating and Air Conditioning Equipment and Systems. Ame rican Society of Heating, Refrigerating and Air - Conditioning Engineers, Inc. A.S. Trust & Holdings, Inc. 2012. HCR- 188C/R - 441A for Use in White Goods Systems. Significant New Alternatives Policy Program Submission to the United States Environmental Protec tion Agency. March 2012. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radia tive Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. ICC IRC. 2012. International Residential Code. International Code Consortium. ICF International. 1997. Physiological Effects of Alternative Fire Prote ction Agents - Hypoxic Atmospheres Conference. Stephanie Skaggs prepared the proceedings of the conference held May 22, 1997 in New London, CT. IPCC/TEAP. 2005. Bert Metz, Lambert Kuijpers, Susan Solomon, Stephen O. Andersen, Ogunlade Davidson, José Pons, David de Jager, Tahl Kestin, Martin Manning, and Leo Meyer (Eds). Safeguarding the Ozone Layer and the Global Climate System. Intergovernmental Panel on climate Change Technology and Economic Assessment Panel. Cambridge University Press, UK. pp 478. Kataoka, O., M. Yoshizawa, & T. Hirakawa 2000. “Allowable Charge Limit of Flammable Refrigerants and Ventilation Requirements.” Daikin Industries. International Refrigeration and Air Conditioning Conference. Paper 506. Available online at: http://docs.lib.purdue.edu/iracc/506 . Mackenzie, F.T. and J.A. Mackenzie. 1995. Our changing planet. Prentice - Hall.

### May 30, 2014 -- Final 18 McKee R.H., D. Herron, M. Saperstein, P. Podhasky, G.M. Hoffman, & L. Roberts. 2013. The Toxicological Properties of Petroleum Gases. International Journal of Toxicology. NFPA . 20 14 . NFPA Liquefied Petroleum Gas Code. 20 14 Edition. OSHA. 2004. “Safety and Health Topics: Isobutane.” February 2004. Available online at: http://www.osha.gov

/dts/chemi calsampling/data/CH_247840.html . UL. 2007. UL 484: Standard for Room Air Conditioners. Underwriters Laboratory. U.S. Department of Energy (DOE). 2008. DOE Handbook

– Tem porary Emergency Exposure Limits For Chemicals: Methods And Practice. Available online at: http://orise.orau.gov/emi/sc apa/files/doe -hdbk 1046 - 2008_ac.pdf

. U.S. Energy Information Administration (EIA). 2013. 2009 Residential Energy Consumption Survey. Table HC7.3 Air Conditioning in U.S. Homes, by Year of Construction, 2009 . Available online at: http://www.eia.gov/consumption/residential/data/2009/#undefined . U.S. EPA 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on the Use of Substitutes for Class I Ozone - depleting Substances: Refrigeration and Air Conditioning. Stratospheric Protection Division. March, 1994. U.S. EPA. 1997. Exposure Factors Handbook. National Center for Environmental Assessment, Office of Research and Development. Available online at: http://www.epa.gov/ncea/pdfs/efh/front.pdf. U.S. E PA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: http://www.epa.gov/oppt/aegl/pubs/define.htm . U.S. EPA . 2014. Draft Assessment of the Potential Impact of Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. Prepared for the U.S. EPA Stratospheric Protection Division by ICF International . February 24, 2014. WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010 , Global Ozone Research and Monitoring Project - Report No. 52, 516 pp., Geneva, Switzerland.