Ju ne 4, 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:**  **Propane (** **R -**  **290) 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 on assessment of their health and environmental impacts. EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of potential human health and environmental risks posed by the substitute in specific applications. EPA has already screened a large number of substitutes in many end
-use applications within all of the major ODS
using sectors including: refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented in a series of Background Documents that are available in EPA's docket. The purpose of this report 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 propane as a substitute for HCFC
- 22 in the residential and light commercial air conditioning (AC) and heat pump end
-use, specifically in window AC units. Table 1 details the composition of the proposed substitute, including the maximum estimated concentrations of impu rities , which may be present in the proposed substitute , as provided by the submitter (allowable impurity levels per 40 CFR Part 82 or under AHRI Standard 700 may be different)
. **Table 1**  **. Composition of Propane**  **Component Chemical**  **Formula CAS Number**  **Concentration (Weight Percent)**  **Proposed Substitute**  Propane C 3 H 8 74 - 98 - 6  98.9 %

**Potential Impurities (maximum concentration)**  Isobutane C 4 H 10 75 - 28 - 5 0.4% n - Butane C 4 H 10 106 - 97 - 8 0.4% Ethane C 6 H 14 74 - 84 - 0 0.2% Propene C 3 H 6 115 - 07 - 1 0.1%Ju ne 4, 2014
-- Final 2 Section 2 of this report summarizes the results of the risk screen for the proposed substitute listed in Table 1 

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

 Section 3 : Atmospheric Assessment  Section 4 : Volatile Organic Compound Assessment  Section 5 : Discussion of End
-Us e Scenario Modeled  Section 6 : Potential Health Effects  Section 7 : Flammability Assessment  Section 8 : Asphyxiation Assessment  Section 9 : End
-Use Exposure Assessment  Section 10 : Occupational Exposure Assessment  Section 11 : General Population Exposure Assessment  Section 12 : References 

### 2. **SUMMARY OF RESULTS** Propane is recommended for SNAP approval for residential and light commercial room AC units that comply with Underwriters Laboratory (UL) Standard 484: Room Air Conditioners, specifically window AC units, packaged terminal air conditioners (PTAC), packaged terminal heat pumps (PTHP ) , and portable AC units . EPA's risk screen indicates that the use of the proposed substitute will be less harmful to the atmosphere than the continued use of HCF C
- 22 as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime
. Propane is subject to volatile organic compound (VOC) regulations under the CAA (40 CFR 51. 1 00 (s) ). Based on analysis of potential impacts of hydro carbon refrigerant emissions on ground
- level ozone concentrations , VOC emissions from the use of propane in window AC units are not anticipated to contribute significantly to ground level ozone concentrations in the United States
. No significant asphyxiation risks to consumers or toxicity risks to workers, consumers, or the general population are expected. It is expected that procedures identified in the material data safety sheet (MSDS ) for propane and good manufacturing practices will be adhered to
. Additionally, it is expected that the appropriate safety and personal protective equipment (PPE) (e.g., protective gloves, 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, installation, servicing, and disposal of window AC units using propane . Because units are to be installed in locations with adequate space and/or ventilation for the unit’s charge size in accordance with EPA recommendations and the equipment maintenance manual for propane window AC units , as discussed in greater detail in Section 9, significant toxicity or flammability risk to consumers is also unlikely. Additional safeguards , including specified refrigerant concentration limits (RCL) for propane , 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 Laboratory (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 toxicity and flammability data are included. 3 Ventilation for Acceptable Indoor Air Quality ASHRAE Standard 62 establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. 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.Ju ne 4, 2014
-- Final 3 

### 3. **ATMOSPHERIC ASSESSMENT** This section presents an assessment of the potential risks to the atmosphere posed by the use of propane 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 , propane also has a 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 propane 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 Propane**  **Compared to HCFC -**  **22 and R -**  **410A Refrigerant**  **Ozone Depleting Potential (**  **ODP )**  **Global Warming Potential –**  **100 year ( GWP**  **) a**  **Atmospheric Lifetime in Y** **ears (** **ALT )**  Propane 0 a 3.3 0.0 3 b HCFC - 22 0.05 b 1,810 12 a R- 410Ac 0 a 2,088 NAd NA = Not Available a IPCC 4 th Assessment Report ( Forster et al. 2007 ) b WMO 2010 Scientific Assessment Report (2011) c R-410A is a blend of 50% HFC - 32 and 50% HFC - 125. d Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC - 32 is 4.9 years and the ALT for HFC - 125 is 29 years (IPCC 4 th Assessmen t Report [Forster et al. 2007]). 

### 4. **VOLATILE ORGANIC COMPOUND ASSESSMENT**  Propane is regulated as a VOC under CAA regulations ( 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 United 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 each alternative under submissions received by the SNAP Program at the time of the analysis. End
-uses in the evaluation included a number of types of smaller, self
- contained refrigeration and room air
- conditioning units for which SNAP hydrocarbon applications have been received and/or UL Standards covering flammable refrigerants exist. Th e hydrocarbon emissions from these scenarios were es timated based on U.S. EPA’s Vintaging Model, and their potential contributions to ozone concentrations were assessed using U.S. EPA’s Community Multiscale Air Quality (CMAQ) model. CMAQ modeling was performed for April through the end of September, as the se months presented the largest releases of hydrocarbon refrigerant as well as weather conditions favorable for ozone formation. The ozone concentrations were estimated for the Atlanta, Houston and Los Angeles regions, due to their distinctive geographic s etting 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 lesson more than 0.15 ppb in Los Angeles, the city with the greatest ozone problem. This is

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 sub ject to VOC regulations.Ju ne 4, 2014
-- Final 4 roughly 0.2 percent of the current 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 maximum 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 areas 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 results of this analysis, VOC emissions from the use of propane 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** Propane has been 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 is 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 conditioner 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 propane window AC units installed in a room of 41m3 is 180 grams. 6 However, the submission states that propane window AC units will have a typical cha rge size of 300 grams . Furthermore, UL Standard 484 indicates that the maximum charge size of a window AC unit containing a flammable refrigerant is 1,000 grams. 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, o lder homes (i.e., built before 1994 ) are more likely to use window 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 equipment use window AC units, while the remaining use central air conditioning equipment (EIA 2013). O n 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 to September) , air changes per hour in spaces with a floor area of 900 square feet or less are rep orted 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 (180 grams, 300 grams, and 1,000 grams)
. It is further assumed that an individual is present at the start of the leak and remains in the room with the door closed until the charge is compl etely released. UL 484 assumes that window AC units and their compressors are installed at a height 1 meter above the ground. Based on this location and because propane is denser than air (specific gravity of propane relative to air is 1.52 [air = 1]) , thi s risk screen assume s that a vertical concentration gradient of propane 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

6Under EP A’s proposed limits , for a conservative room of 41m3 , the appropriate cooling capacity would be approximately 6,500 BTU/hr, corresponding to an associated charge size limit of 180 grams.Ju ne 4, 2014
-- Final 5 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 also consistent with the possibility that , in a bedroom scenario, individuals may b e lying close to the floor. Table 3 details the end
-use modeling assumptions used throughout this risk screen (i.e., in Sections 7, 8 , and 9). **Table 3**  **. End** **- Use**  **Scenario Model Assumptions Parameter**  **Assumption s**  **Room Type** Bedroom S ize (m 3 ) 41 a ( 1,450 ft 3 ) Ventilation Rate (air changes per hour) 0
. 11 b ; 0.67 c **Refrigeration Unit** Window AC Charge S ize (g) 180 d ; 300 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
. e Typical charge size ( CHEAA 2011). 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. To protect consumers from the potential dangers of a catastrophic leak from the refrigeration unit, ASHRAE Standard 34 determined refrigerant concentration limits (RCLs) which are intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during refrigerant use (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 in addition to the lower flammability limit, hypoxia No Obs erved Adverse Effect Level (NOAEL ) , and exposure limits, as an additional, conservative limit to ensure that significant flammability, asphyxiation, and end
-use exposure risks , respectively, do not occur. For the occupational exposure analysis, potential risks from chronic and acute worker exposure were evaluated by comparing exposure concentrations to available occupational exposure limits. Potential risks of chronic worker exposure were evaluated using workplace guidance levels (WGL). Risks from potential short
-term consumer exposures were evaluated by comparing exposure concentrations to emergency guidance levels (EGL) . In the absence of an established short
-term exposure limit (STEL), acute exposure guidelines levels (AEGLs) , or an emergency response planning guideline (ERPG), potential short
-term, end
-use exposures were compared to an excursion limit, which was calculated according to the methodology described in ACGIH (2004). 7 Table 4 lists the relevant toxicity limits and RCLs of propane and its impurities, 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.

7 It should be noted that this risk screen evaluates both short
- term occupational and end
- use (i.e., non
- occupational) exposure to ethane and propene 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) and propene (2,500 mg/m3 or 1,50 0 ppm 15
- min TWA), which apply to the general population.Ju ne 4, 2014
-- Final 6 **Table 4**  **. Exposure Limits**  **of Propane**  **and Potential Impurities Component**  **WGL (Long -**  **term Exposure) ppm**  **EGL (Short -**  **term Exposure) p**  **pm Refrigerant**  **Concentration Limit (RCL)**  **ppm** Propane 1,000 a (OSHA PEL) 10,000 c , d (10 min AEGL - 1) 6,900 d (30 min AEGL - 1) 5,300 i Potential Impurities n - Butane 1,000 b (ACGIH TLV) 6,900 e (30 min AEGL - 1) 4,000 i Isobutane 1,000 b (ACGIH TLV) 6,900 f 4,000 i Ethane 1,000 b (ACGIH TLV) 3,000 g (30 min ACGIH Excursion Limit) 2,900 h (15 - min TEEL - 1) 7,000 i Propene 500 b (ACGIH TLV) 1,500 g (30 min ACGIH Excursion Limit) 1,000 i 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 toxici ty 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 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 2.1%)." Therefore, as this IDLH value is based on flammability concerns and not toxicity concerns, it is not used in the evaluation of toxicity risks in this risk screen. d AEGL - 1 available at: http://www.epa.gov/opptintr/aegl/pubs/results96.htm e AEGL - 1 available at: http://www.epa.gov/oppt/aegl/pubs/rest102.htm 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 Calculated as three times the TLV- TWA. (AC GIH 2004) h DOE (2008) i ASHRAE (2010 b ) **Table 5**  **. Explanation of Exposure Limit** **- Related**  **Terminology a**  **Organization Definition**  OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Health ACGIH American Conference of Governmental Industrial Hygienists AIHA American Industrial Hygiene Association **Exposure Limit Definition**  **Explanation Short**  **- Term Exposure**  RCL Refrigerant Concentration Limit The RCL for a refrigerant is intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. The RCL for each refrigerant is the lowest of the Acute - Toxicity Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable Concentration Limit (FCL). Determination assumes full vaporization with no removal by ventilation, dissolution, reaction, or decomposition and complete mixing of refrigerant in the space to which it is released. 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 t he general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. Acute Exposure Guideline Level 2 AEGL - 2 is the airborne concentration (expressed as ppm orJu ne 4, 2014
-- Final 7 mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, lon g - lasting adverse health effects or an impaired ability to escape. Acute Exp osure Guideline Level 3 AEGL - 3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life threatening health effects or death.

ERPG Emergency 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. Excursio n Limit d Excursion Limit Because methane (and other short- chai n 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 exceed ed 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.

TEEL e Temporary Emergency Exposure

Limit 1 TEEL - 1 is the maximum concentration in air below which it is beli eved nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined, objectionable odor. Temporary Emergency Exposure Limit 2 TEEL - 2 is the maximum concentration in air below which 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 abilities to take protective a ction. 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. **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 th at nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect according to ACGIH. a All information in this table taken from EPA (1994) except where otherwise noted. b EPA (2012) c A pplicable to emergency e xposure periods ran ging from 10 minutes to 8 hours. d ACGIH (2004)Ju ne 4, 2014
-- Final 8 e Chemical exposure guidelines to use for emergency planning if no AEGL or ERPG is available. TEELs are developed based on concentration l imits or toxicology parameters (DOE 2008). According to the MSDS, exposure to propane may be hazardous if inhalation, skin contact, or eye contact with propane occurs. The most likely pathway of exposure is through inhalation. Propane can cause symptoms of asphyxiation when present in concentration s 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 can act as a narcotic and cause central nervous system depression, including dizziness, drowsiness, and headaches. If propane is inhale d, person(s) should be immediately removed 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 assist victims of exposure to propane without adequate PPE. At a minimum, a self
- contained breathing apparatus (SCBA) should be worn. Exposures of propane to the skin may cause frostbite. In the case of dermal exposure, the M SDS for propane recommends that person(s) immediately wash the affected area with water and remove all contaminated clothing; if frostbite occurs, bathe ( do not rub) the affected area with lukewarm, not hot, water. If water is not available, cover the affe cted 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 propane to the eyes could cause eye irritation. In case of ocular exposure, the MSDS for propane recommends that person(s) immediately flush the eyes, including under the eyelids, with copious amounts of water for 15 minutes. EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for this decision. The potential health effects of propane can be minimized by following the exposure guidelines and ventilation and PPE recommendations outlined in the MSDS for propane and this risk screen. 

### 7 **. FLAMMABILITY ASSESSMENT**  ASHRAE Standard 34 classifies propane as a Class A3 refrigerant. Propane is flammable when its concentration in air is in the range of 2.1 percent and 9.5 percent by volume (21,000 ppm to 95,000 ppm). In the presence of an ignition source (e.g., static electricity, a spark resulting from a switch malfunction, or a lit cigarette), an explosion or a fire could occur if the concentration of propane exceed s the lower flammability limit (LFL) of 21,000 ppm. As such, propane may pose a significant safety 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 manufacture, servicing, and end
-use. **7 .1**  **Flammability Risks at Manufacture** Propane window AC unit s are currently manufactured by the submitter in China ; the manufacturer currently has no plans to manufacture the se systems in the United States. If the manufacture of these propane systems occur s in the United States, the submitter indicates that release of or exposure to propane is possible at the charge and sealing steps on the window AC unit production line at the manufacturing site (CHEAA 2013)
. Itis therefore important that all relevant standards be followed during the manufacture of window A C units , such as UL 484 . Engineering controls should include normal and local ventilation (e.g., chemical hoods) for standard manufacturing procedures so workers can avoid physical contact with the refrigerant and to limit emission s . In general, use of appropriate PPE consistent with OSHA guidelines is recommended, such as splash goggles, mechanically
-resistance gloves whenJu ne 4, 2014
-- Final 9 handling cylinders , chemically
-resistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene), and protective clothing. All propane storage and transport equipment should be installed with safety devices that minimize the likelihood of catastrophic releases
. For example, NFPA 58 Liquefied 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
. 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 1910. OSHA requirements include proper ventilation and storage practices within manufacturing facilities to prevent fire and explosion. Good manufacturing practices should be adhered to during the manufacture of equipment containing propane . **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 propane . Both servicing and end
-use of propane window AC units are expected to take place in the same location (i.e., the place of installation and use). In order to determine the potential flammability risks during servicing or end
-use in case of a catastrophic release of refrigerant , modeled concentrations of propane immediately following the release of refrigerant were compared to the LFL for propane . As demonstrated in Table 6 , the maximum instantaneous concentration in the lower 1 meter o f the room at a charge size of 180 grams would be approximately 5 ,400 ppm, approximately 8,980 ppm for a 300
- gram charge size , and approximately 29,930 ppm for a 1,000
- gram charge size
. The 180
- gram charge size proposed by EPA (Reasonable Wo rst - Case 1) and the 300
- gram charge size indicated by the submitter (Reasonable Worst
- Case 2) do not present a significant flammability concern. In contrast, the scenario using a 1,000
- gram charge size (Reasonable Worst
- Case 3) both exceed the proposed substitute’s LFL of 21,000 ppm
. However, according to UL 484, a window unit with a charge size of 1,000 grams is not intended for installation in a room with a volume as small as that modele d in the worst
- case scenario (41 m3 ). The maximum instantaneous concentration in the upper portion in the room for all modeled charge sizes is much lower, as o nly 5 percent of the leaked refrigerant is present in this area , and this area has greater volume than the lower 1 meter of the room
. EPA is also proposing to limit charge size s 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 180 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 18 0 41 (1,450 ft 3 ) **5,400** Reasonable Worst- Case 2 300 41 (1,450 ft 3 ) **8,980** Reasonable Worst- Case 3 1,000 41 (1,450 ft 3 ) **29,930** Threshold Analysis 1: Charge Size **700** 41 (1,450 ft 3 ) 21,000 Threshold Analysis 2a: Room Size 180 **11 (**  **345 ft**  **3 )**  Threshold Analysis 2b: Room Size 300 **18 (**  **575 ft**  **3 )**  Threshold Analysis 2 c : Room Size 1,000 **58 (**  **1,920 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 Lowe r Flammability Limit of propane is equal to 21,000 ppm.Ju ne 4, 2014
-- Final 10 c Values provided in this column refers to the concentration in the lower 1 meter of the room , which presents the most conservative risk as 9 5 percent of the leaked refrigerant i s present in this space. For the flammability threshold analyses shown in Table 6 , the conditions at which a flammability concern would exist ( i.e., when the maximum instantane ous concentration in the lower stratum of the bedroom equals the LFL for propane ) were determined. Within the reasonable worst
- case room size of 41 m3 (1,450 ft 3 ) , as shown under Threshold Analysis 1, the charge size of the propane window AC unit would have to be at least 700 grams for a flammability concern to exist , which is greater than EPA’s recommended charge size (i.e., 180 grams) and the largest charge size intended by the submitter (i.e., 300 grams)
. For window AC units with a charge size of 180 grams (see Threshold Analysis 2a in Table 6) the volume of the bedroom would have to be 11 m3 ( 345 ft 3 ) or smaller for a flammability risk to occur. U sing a 300
- gram window AC unit, as shown under Threshold Analysis 2 b , the volume of the room would have to be 18 m3 ( 575 ft 3 ) or smaller for a flammability risk to occur. Using a 1,000
- gram propane window AC unit, as shown under Threshold Analysis 2 c , the volume of the bedroom would have to be 58 m3 ( 1,920 ft 3 ) or less for a flammability risk to occur. According to the results of this flammability analysis, the risk o f 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 size s than those modeled in this assessment 8 and because persons or furniture in the room may reduce the effective volume of the space, window AC units containing propane should not be installed in enclosed areas with effective volumes less than indicated by UL 484 or the Room Air
- Conditioners with Flammable Refrigerants Installation and Service Manual provided by the submitter , unless additional steps are taken to protect against a flammability risk (e.g., higher ventilation rates)
. A ccording to UL 484 , 9 windo w AC units with charge size s of 300 grams and 1,000 grams should not be installed in a room less than 120 m3 (4, 3 00 ft 3 ) and 1,360 m3 (4 8,100 ft 3 ) , respectively. According to ASHRAE Standard 34, the RCL for propane (9.5 g/m3 of propane or 5,300 ppm by volume) should not be excee ded in any room that contains a propane window AC unit. Although the RCL for propane is less conservative than the anticipated release amount of propane under the modeled worst
- case scenario s ( i.e., 180 grams in a 41m3 space, or 4.4 g/m3 and 300 grams in a 41 m3 space, or 7.3 g/m3 ), the RCL is calculated assuming that refrigerant is evenly mixed in the space, whereas this analysis assumes a vertical concentration gradient due to the higher density of propane to air (propane = 1.52, air = 1). End
-users, therefore, should ensure that propane window AC units are installed with an appropriate cooling capacity for the intended cooled space (i.e., avoid installing large window AC units to cool small spaces) that is consistent with manufacturer recommendations and the guidelines of relevant safety standards (e.g., ASHRAE 15 and 34 and UL 484). The submitter additionally indicates that warning labels are present on the equipment indicating that flammable refrigerants are inside the unit as well as notifying the user to read the equipment use instructions which provide safety guidelines for handling propane . Therefore, these guidelines s hould be acknowledged and followed to mitigate flammability risk. The installation of leak prevention devices would further protect against the very limited risk of explosion. In the U.S., window AC units are typically replaced rather than serviced. However, should servicing of window AC units with propane occur , EPA recommends that the ventilation requirements outlined in the MSDS for propane be followed through the use of fans (or other mechanical ventilation devices) and portable refrigerant detectors be used to alert technicians to the presence of flammable gas es in order to mitigate the risk of fire or explosion during catastrophic leak
. Itis also important th at only properly trained and certified technicians handle propane . As a further precaution, certification requirements and training programs for technic ians that handle propane should be developed using these guidelines.

8 International Residential Code requires a minimum of 70 ft2 for a habitable room, or 14 m3 (490 ft 3 ) (ICC IRC 2012). 9 The room sizes provided by UL 484 are based on a mounted window AC unit height of 1.0 m from the floor.Ju ne 4, 2014
-- Final 11 

### 8 **. ASPHYXIATION**  **ASSESSMENT** The risk of asphyxiation for the reasonable worst - case scenario (see Section 5 ) was investigated for propane . In this section, risk of asphyxiation is assesse d 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 and 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 operating, 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 vertical concentration gradient. If the proposed substitute passes the screening analysis with these restrictive assumptions in place, it can be reasonably assumed that no risks of asphyxiation will be present under real
-world conditions. The results of the asphyxiation assessment are summarized in Table 7 below. **Table 7**  **. Asphyxiation Assessment a** 

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

**Concentration in Lower 1**  **Meter b**  Reasonable Worst- Case 1 180 41 (1,450 ft 3 ) **21** Reasonable Worst- Case 2 300 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 180 **0. 40**  **( 14**  **. 1**  **ft 3**  **)** 12 Threshold Analysis 2 b : Room Size 300 **0. 66**  **( 23.5**  **ft 3**  **)** 12 Threshold Analysis 2 c : Room Size 1,000 **2.21 (**  **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)
. In order for a risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) must be reduced to 12 percent. 10 Based on the worst
- case scenario modeling assumptions, propane in window AC units does not present a significant risk of asphyxiation. The concentration of propane in the air in the lower 1 meter of the room following the release of the maximum charge size of 1,000 grams does not exceed 2.3 percent, which has an insignificant impact on the normal concentration of oxygen in air. Because this modeling does not take into account any ventilation which is likely to occur, such as conditioned airflow, open doors, or even openings at the bottom of doors that allow air to flow in and out, as mentioned above, 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 41m3 (1,450ft 3 ), as shown under Threshold Analysis 1, the charge size of the propane window AC unit would have to be at least 18,520 grams f

or asphyxiation to be a concern , which is more than 18 times the largest charge size allowed by UL 484 (i.e., 1 , 0 00 grams). Using a 180
- gr am window AC unit, as shown under Threshold Analysis 2a, the volume of the room would have to be 0. 40 m3 ( 14.1 ft 3 ) or smaller f or asphyxiation to be of concern . Using a 300
- gram window AC unit, as shown under Threshold Analysis 2 b , the volume of the room would have to be 0 .66 m3 ( 23.5 ft 3 ) or smaller f or asphyxiation to be of concern . Using a 1,000
- gram window AC unit, as shown under Threshold Analysis 2 c , the volume of the room would have to be 2.21 m3 ( 78.2 ft 3 ) or smaller f or asphyxiation to be of concern . All of the room sizes modeled in the latter

10 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997).Ju ne 4, 2014
-- Final 12 three scenarios are significantly smaller than the reasonable worst
- case bedroom size (41 m3 [1,450 ft 3 ]) and the minimum bedroom volume typically found in the U.S. 11 To further protect against an asphyxiation 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 34 and UL 484). Additionally, adherence to ASHRAE 34, which provides more conservative concentration limits, will ensure that asphyxiation is not a significant risk. Minimum room s izes according to the RCL stated in ASHRAE 34 and UL 484 can be found in Section 7
. Leak prevention, detection, or mitigation devic es should be installed and the ventilation requirements outlined in the MSDS for propane should be closely followed. If these guidelines are followed, a catastrophic leak of propane is not anticipated to result in a significant asphyxiation risk. 

### 9 **. END**  **- U**  **SE EXPOSURE ASSESSMENT**  This section presents estimates of potential consumer exposures to propane and each of its impurities 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 s outlined in Section 5 with charge size s of 180 grams, 300 grams and 1,000 grams. For the end
-use exposure assessment scenario, 30
- minute TWA exposures for the proposed substitute and each of its impurity c onstituents were calculated using the box model described in the Background Document, which was adapted to estimate concentration s on a minute
-by
- minute basis. These exposures were then compared to the standard toxicity limits presented in Table 4 to asses s 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 performed for propane and all of its impurity constituents; however, only the results for propane are presented in Table 8 . As p ropane is approximately 98.9 percent pure, it presents the greatest risk of exceeding the STEL and thus the most conservative assessment.

11 The 20 12 International Residential Code requires bedrooms to have a minimum volume of 13.9 m3 (490 ft 3 ) (ICC IRC 20 12 ).Ju ne 4, 2014
-- Final 13 **Table 8**  **. End** **- Use Exposure Assessment**  **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 1a 180 41 (1,450 ft 3 ) 0. 11 **5,247** Reasonable Worst- Case 1b 0.67 **4,602** Reasonable Worst- Case 2a 300 0. 11 **8, 745**  Reasonable Worst- Case 2b 0.67 **7,670** Reasonable Worst- Case 3a 1,000 0. 11 **29,151** Reasonable Worst- Case 3b 0.67 **25,566** Threshold Analysis 1a: Charge Size **2 37**  41 (1,450 ft 3 ) 0. 11

6,900 Threshold Analysis 1b: Charge Size **270** 0.67 Threshold Analysis 2a: Room Size 180 **31 (1,020 ft**  **3 )**  0. 11 Threshold Analysis 2b: Room Size **2 7**  **( 890**  **ft 3**  **)** 0.67 Threshold Analysis 3a: Room Size 300 **52 (1,7**  **10 ft**  **3 )**  0. 11 Threshold Analysis 3b: Room Size **46 (1,**  **510 ft**  **3 )**  0.67 Threshold Analysis 4a: Room Size 1,000 **1 73**  **(5,6 8**  **0 ft 3**  **)** 0. 11 Threshold Analysis 4b: Room Size **1 52**  **( 5,000**  **ft 3**  **)** 0.67 Threshold Analysis 5a: Air Exchange Rate 180 41 (1,450 ft 3 ) **0** Threshold Analysis 5b: Air Exchange Rate 300 **1.1** Threshold Analysis 5c: Air Exchange Rate 1,000 **8.6 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 95 percent of the leaked refrig erant in present in this space. In the reasonable worst
- case scenario, catastrophic releases of window AC units with charge sizes of 180 grams, 300 grams, and 1,000 grams were modeled with two different air exchange rates, 0. 11 ACH and 0.67 ACH. In Reaso nable Worst
- Case Scenarios 2a, 2b, 3a, and 3b, the 30
- minute AEGL
- 1 for propane of 6,900 ppm is likely to be exceeded (see Table 8 ). The 30
- min TWA exposure s in Reasonable Worst
- Case Scenarios 3a and 3b , which model a 1,000
- gram charge size and ventilation rate s of 0. 11 ACH and 0.67 ACH respectively , exceed the AEGL
- 2 (17,000 ppm) , but not the AEGL
- 3 (33,000 ppm) for propane. A threshold analysis was performed to determine the charge size, room volume, and ventilation rates where window AC units containing propane could be installed to avoid the short
-term exposure limit for propane . 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 m3 (1,450 ft 3 ) volume with 0. 11 ACH is 2 37 grams and 270 grams with 0.67 ACH. Additionally, the threshold analysis indicates that window AC units with charge sizes of 180 grams, 300 grams and 1,000 grams should not be installed in rooms smaller than 31 m3 (1,020 ft 3 ) , 52 m3 (1,7 1 0 ft 3 ) , and 173 m3 (5,6 8 0 ft 3 ) , respectively , assuming an air ventilation rate of 0. 11 ACH. As shown in Table 8 , these recommended minimum room sizes are smaller if the air ventilation rate is increased to 0.67 ACH. Because window AC units with charge size s of 300 grams and 1,000 grams were modeled in a room size that is much smaller than the size recommended by UL 484 in the reasonable worst
- case scenarios, it is not unexpected that the calculated 30
-minute TWA exposure s for these scenarios exceed the AEGL
- 1 for propane. Th ese potential 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 recommends that the charge size for a propane window AC unit does not exceed the RCL (9.5 g/m3 ) and proposes to require compliance with UL 484 in any space containing a window AC unit, unless proper leak protection devises are in place in order to preventJu ne 4, 2014
-- Final 14 exposures of propane beyond the recommended limits. Smaller accidental releases of the proposed substitute, however, do not pose a significant risk to end
-users. Thus, risk of excessive exposure is minimal if a window AC unit 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 propane . When these conditions and the proposed use conditions of the rule 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 manufacture, installation, servicing, and disposal of propane in window AC units
. To ensure that use of the proposed substitute in window AC units does not pose an unacceptable risk to workers during servicing and disposal, occupational exposure modeling was performed using a box
- model approach
. For a detailed description of the methodology used for this screening assessment, the reader is referred the occupational exposure and hazard analysis described in Chapter 5 of the Background Document. Estimates of refrigerant release per event for various release scenarios and data on number of events in 2010 were obtained from the Vintaging Model. 12 To determine the estimated level of occupational exposure for a constituent in proposed substitute blend, the total anticipated release rate of the refrigerant is multiplied by the weight percent composition of each compound and impurity . For the window AC unit end
-use, 0.4 percent of the equipment charge was conservatively assumed to be released during manufacture and servicing and 50 percent of the equipment charge was conservatively assumed to be released during disposal
. 13 Additionally, EPA is proposing to allow intentional venting or release of propane 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 o ccur over a workday. For window AC unit servicing, it was conservatively assumed that eight events of servicing a unit occur in an 8
-hour work day
. For disposal, it was conservatively assumed that 10 units are disposed during an 8
-hour work day. The model ed exposure concentrations were compared to short
-term occupational exposure limits at installation and servicing and long
-term exposure limits at disposal. **10 .1**  **Occupational Exposure during Manufacture** Propane window AC units are currently manufactured by the submitter in China , and the manufacturer currently has no plans to manufacture the se systems in the United States. As indicated by the submitter, release of or exposure to propane is possible at the charge and sealing steps on the window AC unit production line. If the manufacture of these propane systems occur s in the United States, the proposed substitute’s MSDS should be referenced and proper engineering controls and PPE should be used. Propane is not expected to pose a risk to workers during manufacture when the engineering controls and PPE recommendations and referenced in the MSDS for propane are followed. Engineering controls should include normal and local ventilation (e.g., chemical hoods) for standard manufacturing procedures so workers can avoid physical contact with the refrigerant and limit emission s . The manufacturing

12 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 equip ment determines such factors as leak rate, charge size, number of units in operation, and the initial ODS substance that the equipment contained. The service leak rate and disposal release rate assumptions are consistent with the window AC end
-use in Vintaging Model version VM IO file_v4.4_11.6.12. 13 During disposal it is assumed that 10 0 percent of the refrigerant charge remains in the unit.Ju ne 4, 2014
-- Final 15 equipment is designed to minimize potential emissions while engineering controls at the manufacturing facility include w arning alarms for propane leakage and ventilation systems. M aintenance manuals describe procedures to reduce leakage and prior safety training is required for all personnel who work on the production line
. In general, use of appropriate 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), and protective clothing. Because of established equipment design and manufacture practices, exposures to propane will be unlikely. Thus, EPA does not believe that manufacturing of AC units with propane under these workplace conditions presents a concern to workers. Containers should be stored in cool, dry conditions (maximum storage temperature should be 40  C) in well
- sealed receptacles and should not be allowed to contact open flames, glowing metal surfaces, or electrical heating elements. EPA believes that when proper handling and disposal guidelines are fo llowed in accordance with both good industrial hygiene and manufacturing practices and the MSDS for propane , there is no significant risk to workers during the manufacture of propane window AC units. **10 .2**  **Occupational Exposure at**  **Installation and Servicing**  Window AC units are expected to be serviced rarely, since this type of equipment is hermetically sealed and in the U.S. is often replaced rather than serviced if the charge leaks. Nevertheless, the potential occupational exposure for those situations where servicing takes place were analyzed
. T he possibility of a release during installation was also considered
. The maximum 30
- minute time
-weighted average (TWA) exposure for propane and its potential impurities were estimated for servicing window AC units charged with 180 grams, 300 grams and 1,000 grams of refrigerant . As summarized in Table 9 , occupational exposure to propane is anticipated to be significantly below the short
-term exposure limits (STEL) with a 180
- gram, 300
- gram or 1,000
- gram charge size for both 0.4 percent release and 100 percent release of refrigerant during servicing
. Therefore, worker exposure to propane during installation and servicing is not a significant concern. T echnicians should follow the procedures outlined in the MSDS and maintenance 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 propane . Systems should be installed by following procedures of ASHRAE Standard 147 including conducting leak checks once a system is installed (ASHRAE 20 13 ). 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 propane during installation and maintenance is unlikely. **Table 9**  **. Occu pational Risk Assessment at Servicing**  **a Component**  **30 -**  **minute TWA**

**Occupational Exposure (ppm)**  **Charge size: 180 grams**  **30 -**  **minute TWA**

**Occupational Exposure (ppm)**  **Charge size: 300 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 1.42 356 2.37 593 7.90 1,980 6,900 b Potential Impurities Isobutane 0.004 1.1 0.007 1.8 0.024 6.1 6,900 b n - Butane 0.004 1.1 0.007 1.8 0.024 6.1 6,900 b Ethane 0.004 1.1 0.007 1.8 0.023 5.9 3,000 c Propene 0.002 0.4 0.003 0.6 0.008 2.1 1,500 c a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b AEGL - 1 ; S ee Table 4 for more information c ACGIH (2004)Ju ne 4, 2014
-- Final 16 **10 .**  **3 Occupational Exposure**  **at Disposal**  D isposal of propane window AC unit s 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 draining the refrigerant from the refrigeration units into cylinders (e.g., connecting of pipes). Such activities and related exposure is anticipated to occur within 15
- 30 minutes (per event/day). Table 10 displays the maximum estimated 8
-hour TWA occupational exposure levels of propane and its impurities during disp osal. Based on the assumptions described in the beginning of S ection 10 , the modeling indicates that 8
-hour worker exposure concentrations for propane and its impurities during the 50 percent release scenario will not exceed the long
-term exposure limits of any of the individual component s during disposal of propane for window AC units with a charge size of 180 grams or 300 grams . Under the 100 percent disposal release scenario for the 300
- gram unit and the 50 percent and 100 percent release scenario s for the 1,000
- gram unit, the modeling indicates that occupational exposure could exceed the 8
-hour long term exposure limits for propane. However, the occupational exposure to the proposed substitute during disposal does not represent a true occupational health hazard because the estimated exposure concentrations for all scenarios do not exceed the 8
-hr AEGL
- 1 for propane, which is 5,500 ppm. Furthermore, these exposures were derived using conservative assumptions (e.g., no ventilation or use of PPE assume d) , 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.

**Table 10**  **. Occupational Risk Assessment at Disposal a**  **Component 8**  **- Hour TWA Occupational** 

**Exposure (ppm) Charge size: 180 grams**  **8 -**  **Hour TWA Occupational Exposure (ppm)**  **Charge size: 300 grams 8**  **- Hour TWA Occupational**  **Exposure (ppm) Charge size: 1,000 grams**  **8 -**  **Hour Long Term Exposure**  **Limits (ppm) 50%**  **Release 100%** 

**Release 50%** 

**Release 100%** 

**Release 50%** 

**Release 100%** 

**Release** Propane 315 629 524 1,050 1,748 3,500 1,000 b Potential Impurities Isobutane 0.97 1.93 1.61 3.22 5.36 10.7 1,000 c n - Butane 0.97 1.93 1.61 3.22 5.36 10.7 1,000 c Ethane 0.93 1.87 1.56 3.11 5.19 10.3 1,000 c Propene 0.33 0.67 0.56 1.11 1.85 3.7 500 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 are above the exposure limits for propane for the 100 percent disposal release scenario for 300g and 1000 g charge sizes , the recommendations for proper engineering controls and PPE in the MSDS for propane should be followed. Adequate ventilation should always be established during any use, handling, storage , or disposal of propane . Engineering controls should include vapor- in air detection systems and local exhaust ventilation during use and disposal of propane to prevent dispersion throughout the work place. In addition, an eye wash and safety shower should be near the manufacturing facility and locations where propane 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). EPA believes that if proper handling and disposal guidelines are followed in accordance with good industrial hygiene and manufacturing practices and the MSDS for propane , there is noJu ne 4, 2014
-- Final 17 significant risk to workers during the manufacturing, installation, servicing, and disposal of propane in window AC units. 

### 11 **. GENERAL POPULATION EXPOSURE**  **ASSESSMENT** Propane is not expected to cause a concern for human health in the general population when manufactured for use and used as a refrigerant in window AC units. At room temperature, propane is a gas and, therefore, releases to ground or surface water are not anticipated , as propane 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 manufacturing operations occur, including filling of window AC units, engineering controls should be used (e.g., carbon absorption units or scrubbers) to collect propane and prevent the release of propane to the atmosphere. EPA believes that by using proper engineering cont rols and by following disposal and containment recommendations outlined in the proposed substitute’s MSDS, exposure to propane is not expected to pose a significant toxicity risk to the general population.Ju ne 4, 2014
-- Final 18 

### 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 online at: www.acgih.org. ACGIH. 2012. 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. 2010b . Standard 34: Designation and Safety Classification of Refrigerants. American Society of Heating, Refrigerating and Air
- Conditioning Engineers, Inc. ANSI/ASHRAE. 2013 a . Standard 62: Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigerating and Air
- Conditioning Engineers, Inc. ANSI/ASHRAE. 2013 b . Standard 147: Reducing the Release of Halogenated Refrigerants from Refrigerating and Air Conditioning Equipment and Systems. American Society of Heating, Refrigerating and Air
- Conditioning Engineers, Inc. Braker W, Mossman AL. 1980. Matheson gas data book. 6th ed. Secaucus, NJ: Matheson Gas Products, pp. 615 623. Centers for Disease Control and Prevention (CDC). 20 10. NIOSH Pocket Guide to Chemical Hazards. Available online at: http://www.cdc.gov/niosh/npg/default.html China Household Electrical Appliance Association (CHEAA). 2011. Propane for Use in Residential and Light Commercial Air Conditioning and Heat Pumps. Significant New Alternatives Policy Program Submission to the U.S. Environmental Protection Agency. September 2011. China Household Electrical Appliance Association (CHEAA). 2013. Incompleteness Letter for Propane in Residential and Light Commercial Air Conditioning and Heat Pumps SNAP Submission. October 2013. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007:The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [S olomon, 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 Protection Agents
- Hypoxic Atmospheres Conference. Stephanie Skaggs prepared the proceedings of the conference held May 22, 1997 in New London, CT.Ju ne 4, 2014
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