## MEMORANDUM

To: Margaret Sheppard , U.S. EPA

CC: Karen Thundiyil and Monica Shimamura , U.S EPA

From: Emily Herzog, Ed Carr, Kara Altshuler, Toby Krasney, Marian Van Pelt, Mark Wagner, ICF
International

Date: August 4 , 200 9

Re: Revised Final Draft Assessment of the Potential Impacts of HFO

- 1234yf and the Associated Production of TFA on Aquatic Communities and Local Air Quality (Deliverable under EPA
Contract Number EP

- W

- 06

- 008 Task Order 0 26 , Task 06)

Please find attached a revised final draft of a paper that examines the emissions of HFO

- 1234yf and the associated production of TFA under several scenarios. The assessment has been revised based on updates made to the Vintaging Model assumptions for MVAC end uses. Specifically, the updates include smaller charge sizes and a reduction in future market growth rates. While market penetration of the substitute is assumed to be the same as in the previous set of assumptions, the growth of the overall sector is assumed
to be less than the annual 2.6 per cent growth rate previously assumed

. The revised charge size and growth rate assumptions have result ed in a reduction of projected future emissions of HFO

- 1234yf.

Please contact Mark Wagner at 202

- 862

- 1155 with any questions or comments.

# Rev ised Draft A ssessment of the Potential Impacts of

HFO

- 1234yf and the Associated Production of TFA on Aquatic Communities and Local Air Quality

Prepared for:
Stratospheric Protection Division
Office of Atmospheric Programs

U.S. Environmental Protection Division

1310 L Street, NW
Washington, DC 20005

Prepared by:

ICF International

1725 E ye Street, NW, Suite 1000
Washington, DC 20006
July 31

, 2009

### TFA Assessment

1 100

- year GWPs of Selected HCFCs and HFCs

Gas IPCC Second

Assessment Report (SAR) IPCC Fourth

Assessment Report (AR4) HCFC

- 22 1,500 1,810

HCFC

- 123 90 77

HCFC

- 124 470 609

HCFC

- 141b 600 725

HCFC

- 142b 1800 2,310

HFC

- 23 11,700 14,800

HFC

- 32 650 675

HFC

- 125 2,800 3,500

HFC

- 134a 1,300 1,430

HFC

- 143a 3,800 4,470

HFC

- 152a 140 124

HFC

- 227ea 2,900 3,220

HFC

- 236fa 6,300 9,810

HFC

- 245fa NA 1 ,030

HFC

- 365mfc 860 794

Source: IPCC (1996), IPCC (2007) 

## Executive Summary

HFO

- 1234yf is a chemical under development for use in motor vehicle air conditioning ( MVACs) and has the potential to be used more broadly in other end use sectors. Although HFO

- 1234yf has a low global warming potential (GWP) and is thus a desirable alternative to commonly used hydrofluorocarbons (HFCs), there is concern that use of HFO

- 12 34yf could negatively impact both local air quality and aquatic communities. HFO

- 1234yf has a photochemical ozone creation potential (POCP) that could potentially lead to increased levels of ground ozone. Additionally, there is concern associated with th e atmospheric degradation of HFO

- 1234yf, which results in the production of trifluoroacetic acid (TFA). TFA has the potential to accumulate on soil, on plants, and in aquatic ecosystems over time and to impact the supported plant and animal communities. The following paper describes the production and fate of TFA, provides an in

- depth discussion of the toxicity of TFA, discusses the scenarios developed for this analysis, and discusses the potential impacts HFO

- 1234yf could have on aquatic ecosystems, soil

, plants, and local air quality.

The scenarios developed for this analysis project HFO

- 1234yf emissions and subsequent production of TFA up to 2050 based on market penetrations in the domestic market. In conjunction with three dimensional air quality m odeling conducted using EPA’s Community Multiscale Air Quality (CMAQ) model (CMAQ

- Byun, D. W., and J. K. S. Ching. 1999 ) these projections were used to estimate the maximum potential concentration of TFA in rainwater . These projections were also localiz ed and used to predict the potential increase in ground level ozone. From this analysis, it was concluded that the projected maximum concentration of TFA in rainwater should not result in a significant risk of ecotoxicity and that n on

- attainment resulting from

HFO

- 1234yf emissions is unlikely to be a major concern for local air quality in most locations.



## 1. Introduction

Since the inception of the Significant New Alternatives Policy (SNAP) program, a large number of substitutes have been reviewed in support o f the development and commercialization of viable replacements for ozone depleting substances (ODS)
across all of the end use sectors that have traditionally used ODS. Approved substitutes have included hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), blends, hydrocarbons,
and not

- in

- kind alternatives. The HFCs have been a significant alternative for many sectors because of
their non

- ozone depleting nature, but due to the high global warming potential (GWPs) of HFCs, new low

GWP alternatives ar e being developed. In particular,

HFO

- 1234yf is a chemical under development for use in motor vehicle air conditioning (MVACs) and has the potential to be used more broadly in the refrigeration/air conditioning end use sectors.

### TFA Assessment

2 Sources of TFA

Species Global TFA

Production (t yr

- 1 )

Halothane 520

Isoflurane 280

HCFC

- 123 266

HCFC

- 124 4440

HFC

- 134a 4560
Fluoropolymers 200
TFA (lab use etc) Negligible

Total 10,266
Source: IPCC/TEAP 2005 HFO

- 1234yf is proposed to replace HFC

- 134a in MVACs and has a particularly low GWP of 4.4 compared to the HFCs and HCFCs currently in use (as shown in the text box above), HFO

- 1234yf has the potential to significantly reduce the climate impacts of MVACs as well as that of other sec tors (Papadimitriou et al. 2007).

Although the use of HFO

- 1234yf could potentially mitigate greenhouse gas emissions, it could also potentially contribute to increased levels of ground level ozone. The photochemical ozone creation potential (POCP) of HFO

- 1234yf is dependent on regional conditions and is expected to be similar to that of ethylene ( Papadimitriou et al. 2007). This POCP value is significantly higher than that of HFC

- 134a, which is nearly zero, and therefore HFO

- 1234yf may pose a risk to loca l air quality, if emitted in sufficient quantities.

There is additional concern associated with the atmospheric degradation of HFO

- 1234yf which results in the production of trifluoroacetic acid (TFA). TFA is a well

- known environmental
contaminant that res ults from the degradation of halothane (an anesthetic introduced clinically in 1956), isoflurane, and fluoropolymers as well as HFC

- 134a, HCFC

- 123, and HCFC

- 124. In its 2006 report on Environmental Effects of Ozone Depletion
and Its Interactions with Clim ate Change, the United National Environment Programme (UNEP) stated that risks to humans and the environment from TFA and other degradation products
of HCFCs and HFCs “are considered minimal.” HFO

- 1234yf was
not considered in the basket of HFCs at the tim e that UNEP prepared its 2006 report.

At the current rate of production from atmospheric degradation of HFCs and HCFCs, the level of TFA is projected to reach close to 0.0001 mg/L in 2020 in rainwater , about 1,000 times lower than the lowest reported no observed effect concentration of 0.1 2 mg/L (Berends et al. 1999). However, the rate of production of TFA from HFO

- 1234yf is significantly higher than that associated with HFC

- 134a. With the anticipated use (and associated emissions) of HFO

- 1234yf, TFA has the potential to accumulate in seasonal wetlands, which have both little to no outflow and high evaporation rates (e.g., vernal pools, playa lakes), over time and may impact the supported plant and animal communities in those wetlands.

This paper examine s the emissions of HFO

- 1234yf and the associated production of TFA under several scenarios and assesses the potential impacts of HFO

- 1234yf and TFA on aquatic communities and local air quality. The remainder of the document is organized as follows:

 Section 2 describes the production and fate of TFA;

 Section 3 provides an in

- depth discussion of the toxicity of TFA;

 Section 4 discusses the scenarios developed for this analysis and the resulting emissions of HFO

1234yf and production of TFA; and

 Section 5 disc usses the results of this analysis, presents an assessment of the potential impacts on aquatic ecosystems and local air quality, and identifies the limitations of the analysis.

### TFA Assessment

3 

## 2. Production and Environmental Fate of Trifluoroacetic acid (TFA)

Trifluoroaceti c acid (TFA) is produced during the atmospheric breakdown of many fluorocarbons (e.g.,

CFC replacements) , including HFO

- 1234yf . The process is initiated by the gaseous reaction of these fluorocarbons with hydroxyl (OH) radicals, eventually resulting in ca rbonyl products. These halogenated carbonyl compounds remain in the atmosphere for about 5 days before they are encapsulated into water droplets and hydrolyzed to TFA ( Papadimitriou et al. 2007)

.

D ue to the re

- evaporation of cloud droplets

, TFA may als o re

- evaporate to the gas phase . A small portion (at most 5%) of gas phase TFA is estimated to react with OH and be dry

- deposited to the earth’s surface (Kotamarthi et al. 1998). However, TFA is considered highly soluble and is instead expected to

reincor porate into cloud and rainwater, eventually being wet

- deposited to the oceans and land surfaces (Kotamarthi et al. 1998). After deposition, TFA enters aquatic environments.

TFA is a strong acid with a reported p K a range of ~0.25

- 0.5; therefore, it is exp ected to completely ionize at any pH that occurs naturally (Boutonnet et al. 1999; HSDB 2008; Kotamarthi et al. 1998). Due to its high solubility, volatilization from aqueous solution is not considered to be a significant transport pathway. In the aqueou s phase, TFA does not absorb light at wavelengths greater
than 250

- 290 nm (Boutonnet et al. 1999; HSDB 2008), thus excluding photolysis as a degradation pathway.

There are few studies available that provide information
on the movement of TFA in solid and liquid media. Based on a low Henry’s Law constant and a low K ow (n

octanol/water partition coefficient) (Franklin 1993), it has been predicted that TFA would partition predominantly in water (Bowden et al. 1996; 1998). However, studies of TFA adsorption in soils have been performed in both upland forest and forest wetland environments in the Hubbard Brook Experimental Forest in New Hampshire, with varying results (Likens et al. 1997; Richey et al. 1997). These studies indicate that TFA is measurably retai ned in soils in those environments, with wetland systems retaining more applied TFA than the forest system. For example, within 1

- 3 weeks, applied TFA moved through the forest soil profile with drainage water, and more than 70% of the TFA exited the uplan d forest in drainage water. The authors suggested that TFA would likely be leached from the soil and enter drainage waters { over approximately 2 years until the TFA concentrations returned to pre

- application levels. In the case of the forest wetland, TF A did not move readily with water, and <5% of the applied TFA moved out of the wetland in drainage water. Interestingly, the authors did not see an increased concentration of TFA in drainage waters following dry spells and the drying of the wetland, indic ating that the compound was not concentrating due to evaporation. The authors interpreted these data to indicate the compound was being retained in the vegetation (20

- 50%) and forest wetland soils (20

- 60%).

A separate study done by the researchers inves tigated the properties of soils that affect TFA retention (Richey et al. 1997). The data indicate that soils with greater amounts of organic matter preferentially Chemical and Physical Properties of TFA

Molecular Formula CF 3 C(O)OH

Molecular Weight 114.02

Vapor Pressure 1.10 x 10 2 mm Hg

Boiling Point 72.4  ̊C

Melting Point

- 15.4  ̊C

Log K ow 0.50

pK a 0.25

- 0.5

K oc 3

Henry’s Law Constant 1 .11 x 10

- 7 atm

- m 3 /mol

Solubility Miscible in water at 20  ̊C

Source: Hazardous Substance Data Bank

### TFA Assessment

4 retain TFA compared to well

- drained, aerobic soils, with organic soils from wetlands, peatla nds, and a boreal forest showing the greatest retention of the compound. Further, TFA was retained to a greater extent in lower pH environments, but was not retained in the presence of high concentrations of fluoride, chloride, and sulfate ions. As menti oned before, TFA is a strong acid; these data suggest that soils impacted by acid rain may be further impacted by the deposition of TFA, because of its acidity, although the presence of SO 4 - (currently a primary component of acid rain) in large quantities will inhibit TFA retention. Studies evaluating effects of TFA deposition/adsorption on soil or sediment chemistry
have not been identified. Effects of TFA on soil microbial communities are described below.

Studies show that TFA is extremely persistent in aquatic environments. The estimated half

- life for degradation of TFA in typical environmental conditions via reaction with hydroxyl radicals in water

would be  100 years (Ellis et al. 2001). Further, data provided by Alternative Fluorocarbons

Environment al Acceptability Study (AFEAS) member companies indicates that TFA is resistant to biodegradation (Franklin 1993).



## 3. Toxicity of Trifluoroacetic Acid (TFA)

3.1. Aquatic and Environmental Toxicity 1

TFA is mildly toxic to plant life (i.e., phytotoxic). In certain environmental conditions, TFA could reach concentrations in the future that may be toxic to surrounding plant life. For example, studies show that as seasonal wetlands evaporate, the remaining TFA is concentrated; TFA in these standing pools can be

reta ined for years, adding to long

- term accumulation of TFA in wetlands (Cahill et al. 2001). Increased concentrations of TFA can inhibit growth in the most sensitive plants and may affect the survival of endangered and endemic plant species (Cahill et al. 200 1). Lower aquatic life forms, such as bacteria, small invertebrates, and oligochaete worms, do not accumulate large quantities of TFA, and are not significantly impacted by the compound (Boutonnet et al. 1999). According to a study on the aquatic

toxicit y of TFA, systems exposed to a concentration of 0.10 mg/L are expected to experience no adverse effects (Berends et al. 1999), although many organisms show no toxic effects at much higher concentrations of the compound (see Table 1 below).

Lowest observed effect concentrations (LOEC) and no observed effect concentrations (NOEC), as summarized by Boutonnet et al. (1999), 2 are shown in Table 1

.

1 T he toxicity of TFA has been evaluated in algae, microbial benthic organisms, fish, and freshwater plants. Terrestrial plant, laborator y animal, and human study data are not reviewed in this section.

2 Research sponsored by the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS) and conducted by independent scientists at universities, private research organizations, and go vernment laboratories.

### TFA Assessment

5 Table 1 : Summary of Studies on the Aquatic Toxicity of Sodium Trifluoroacetate (mg/L) Aquatic Organisms EC50 * LOEC ** NOEC *** Selenastrum capricornutum (freshwater green alga) (new name: Raphidocelis subcapitata ) 4.8 1.5 0.36 0.12 0.15

Anabaena flos

- aquae (blue

- green alga) 2400 12 00 600

Navicula pelliculosa (freshwater diatom) 1200 1200 600

Skeletonema costatum (marine diatom) --- --- 2400

Chlorella vulgaris (freshwater green alga) --- --- 1200

Scenedesmus subspicatus (freshwater green alga) --- --- --- Chlamydomona s reinhardtii (freshwater green alga) --- --- >120

Microcystis aeruginosa (blue

- green alga) --- --- >117

Phaeodactylum tricornutum (marine alga) --- --- >117

Dunaliella tertiolecta (marine alga) --- --- >124

Euglena gracilis (freshwater alga) --- --- >112

Daphnia magna (crustacea) --- --- 1200

Brachydanio rerio (Zebra fish) --- --- 1200

Lemna gibba (duckweed)

--- vegetative growth 1100 600 300

*EC50 = test concentration resulting in a 50% effect; the table lists EC50 for biomass (a dverse effects on growth)
**LOEC = lowest observed effect concentration
***NOEC = no observed effect concentration
Source: Boutonnet et al. 1999

At an exposure level of 1200 mg/L of sodium trifluoroacetate, no effects were seen on either Brachydanio rerio ( zebr a fish) after 96 hours or Daphnia magna (a water flea) after 48 hours (Boutonnet et al. 1999) . In duckweed, mild negative growth eff ects were seen on frond and weight increase at the same exposure level , while no effects were noted at 300 mg/L . Toxic ity tests conducted with 11 species of algae (Berends et al. 1999) found that, f or ten of these species

, the effect concentration for 50% of the test organisms ( EC 50 ) was greater than 100 mg/L. The lowest threshold for effects w as observed for
the unicell ular alga

, Selenastrum capricornutum ; the no

- effect concentration (NOEC) was 0.12 mg/L

.
Species of flora and fauna found in vernal pools and other seasonal wetlands vary with geography, and are established in unique environmental niches. Plant species te nd to be annuals, as perennials are not adapted to the seasonality of the rainfall. Of the species listed in Table 1, daphnia magna (crustacean) is a common resident of vernal pools. Freshwater fairy shrimp ( Branchinecta lynchi ) and tadpole shrimp ( Lepid urus packardi ), which are found only in California, are obligate vernal pool species that define these wetlands. Neither have been tested in published TFA exposure or toxicity studies to date. These

### TFA Assessment

6 species are adapted to living in an ecosystem that has v arying pH and salinity gradients, but there is currently no information regarding what, if any, effects increasing TFA concentrations would have on the life cycle of these organisms.

More recent research results are summarized in Table 2 . These data were taken from articles relative to the toxicity of TFA in fish, aquatic plants, and freshwater benthic microbial communities, and they indicate that TFA exhibits low toxicity in these receptors.

Table 2 : Summa ry of Additional Toxicity Studies of Trifluoroacetate (mg/L) Aquatic Organisms EC50 /LC50 LOEC NOEC

Danio rerio (Zebra fish) (Wiegand et al., 2000)

--- 1,000 (low elevation of GST activity) 4,000

(no acute effects)

Myriophyllum sibiricum, Myriophyllum spicatum (aquatic plants) (exposure to trichloroacetic acid and TFA mixture for 49 days) (Hanson et al., 2002) --- --- 10

Lemna gibba, Myriophyllum sibiricum, Myriophyllum spicatum (aquatic plants [macrophytes]) (Hanson and Solomon, 2004a) EC 50 rang e: 222.1

- 10,000 M. sib. : 300

M. spic. : 100 L. gibba : 100 M. sib. : 100

M. spic. : 30 L. gibba : 30 Pimephales promelas (Fathead minnow) (Geiger et al., 1988, as cited in ECOTOX) 7.79

- 1.28

--- ---

Freshwater benthic microbial communities in stream sediments (Bott and Standley, 1998)

--- --- 0.00002 to 0.2 (no effect on acetate metabolism) *GST = glutathione S

- transferases *EC50 = test concentration resulting in a 50% effect; the table lists EC50 for biomass (adverse effects on growth)
*LC50 = conc entration at which 50% of the organisms show an effect (mortality)
*LOEC = lowest observed effect concentration
*NOEC = no observed effect concentration

The combined impact of TFA and other haloacetic acids is not likely to create a significant impact on exposed species. Hanson et al. (2002) tested two aquatic plant species with a mixture of trichloroacetic acid (TCA) and TFA at concentrations up to 10 mg/L, and observed reversible effects on pigment concentrations at the start of the study, but no advers e effects thereafter. The authors conclude that, based on the lack of morphological or biochemical effects on these aquatic macrophytes, it is unlikely that the TCA/TFA mixture causes toxicity at the currently measured environmental concentrations,
which they report as 0.01 mg/L. Hanson and Solomon (2004a) tested the toxicity of TFA and other haloacetic acids (HAA) in the laboratory with three aquatic plants; mass and root measures, such as root number and root length, tended to be the most sensitive indi cators of HAA toxicity. The results of this study were used in an ecological risk assessment for macrophytes and HAA (Hanson and Solomon, 2004b). The authors compare the thresholds of toxicity for the species tested to measured
concentrations of HAAs in the environment from Canada, Europe, and Africa to calculate hazard quotients. The Hazard Quotient, as defined by Hanson and coworkers, is the ratio of the highest expected environmental concentration of HAA (EEC) and the toxicological benchmark concentra tion (TBC); HQ = EEC/TBC. An HQ of greater than 1 indicates a “potential for toxic effects to occur” while those less than 1 essentially indicate no risk (“effects are unlikely”). The calculated hazard quotients are extremely low (those for TFA with the t hree macrophytes were all ≤0.000088 or lower), indicating that HAAs do not pose a significant risk to freshwater macrophytes at current environmental concentrations

### TFA Assessment

7 for both single compound and mixture exposures. The thresholds for toxicity in these calcu lations ranged from 4.1 mg/L to 45.9 mg/L, concentrations which are 400

- 4500

- fold greater than those currently detected in the environment (Cahill et al. 2001). Therefore, these data indicate that even in
the event of increased environmental concentrations of TFA, which might result from increased use of

HFO

- 1234yf, the risk to environmental receptors is expected to be small.

The potential for bioconcentration in aquatic organisms is low (HSDB 2008), based on one classification scheme (Franke et al. 1994). An estimated BCF of 3 for TFA was calculated in fish, using an estimated log

K ow of 0.50 (Meylan and Howard 1995) and a regression

- derived equation (Meylan et al. 1999). Boutonnet et al. (1999) conclude that TFA does not accumulate significantly in lowe r aquatic life forms
such as bacteria based on results from Bott and Standley (1994, as cited in Boutonnet et al. 1999) in which incorporation of radiolabeled TFA increased over 2.5 years from 0.005% of total counts to 0.024%
of total counts

, and based on low bioconcentration factors (BCF) derived in studies with green algae (BCF of approximately 10) and duckweed (BCF of 1.0 to 1.6)

.
As seasonal wetlands evaporate, TFA can remain in place and can concentrate over several years, resulting in long

- term accum ulation. This accumulation may be linked to increased concentrations of TFA in plants in these wetlands, but studies in animals following long

- term exposure to TFA have not been done to date. In one study, t he highest TFA concentrations in water, which o ccurred just prior to the pools drying up, were in the 0.00 2 to 0.01 mg/L range . This concentration range is lower than the lowest reported NOEC of 0.12 mg/L for a species of freshwater green alga e. P lants exposed to high aqueous concentrations of TFA with in the seasonal pools had elevated TFA concentrations with a median concentration of 279 ng/g dry weight in their tissues

, as compared to 33 ng/g for species growing outside the pools (Cahill et al. 2001)

. A study of the effects of TFA on vernal pool soil microbial and plant communities indicated that, at the test concentrations, TFA will not adversely affect the development of soil microbial communities and vernal pool plant species. Microbial respiration was not affected by TFA exposures up to 10 mg/L, and microbial degradation of TFA was not observed in soils incubated for three months. In addition, no adverse physiological responses were observed in wetland plants exposed to 0.1 and 1 mg/L TFA. TFA did accumulate in the foliar tissue of wetland plants as a function of root exposure concentration, but the concentrations in foliar tissue leveled off and/or declined with time (Benesch et al. 2002). Thus, the test concentration of 1 mg/L is a NOEC for plant species in vernal pools.

Studies of stomatal upt ake in plants following dry deposition are limited. For TFA that is dry deposited, ponderosa pines were shown to take up TFA through their foliage (stomatal uptake) at concentrations of 0.0015 and 0.01 mg/L for four months (Benesch and Gustin 2002). The s tudy authors prevented misted TFA from reaching the roots of the trees to ensure they evaluated only foliar uptake. Although TFA concentrations were shown to increase in the pine needles over the course of the study, no visual morphological or photosynthe tic effects were noted at either concentration. No NOEC values have been identified based solely on dry deposition of TFA, or on a combined wet/dry deposition model.

In conclusion, NOECs from the published literature for the most sensitive species were:

 0 .12 mg/L for freshwater green algae

 1200 mg/L for a fish species

 No observed adverse effects at up to 10 mg/L for vernal pool microbial species and up to 1 mg/ L for vernal pool plant species

### TFA Assessment

8 

### 3.2. Human and Animal Toxicity

TFA has low inhalation toxicity, modera te oral toxicity, and the irritation threshold for humans is 54 ppm (Boutonnet et al. 1999). The free acid is considered a strong skin and eye irritant. TFA is not significantly metabolized by mammals. The sodium salt of TFA (NaTFA) has a much lower toxi city than the free acid and will be the focus of this section, as the free acid is not likely to be present at high concentrations in environmental media. Animal studies show that the target organ of TFA and its
sodium salt is the liver. Single doses of u p to 2000 mg/kg NaTFA in male mice resulted in fatty liver changes, accompanied by increases in glycogen and vacuolization (Rosenberg and Wahlstrom 1971, as cited in Boutonnet et al. 1999). Repeated oral dosing of male rats with NaTFA at up to 150 mg/kg

- da y resulted in significantly increased relative liver weights with decreased liver glycogen content (Stier et al. 1972, as cited in Boutonnet et al. 1999), and doses of up to 500 mg/kg

- day of trifluoroacetate caused increased liver cell size with peroxisoma l proliferation (Just et al., 1989, as cited in Boutonnet et al.; 1999). The peroxisomal proliferation is unique to the rat, as this effect was not observed in dosed guinea pigs. Single doses of 10 mg/kg (ip) or 25 mg/kg (oral) TFA in male rats resulted in no adverse testicular effects. Neither TFA nor its salts have been studied in reproductive or developmental assays; TFA was present in the amniotic fluid of halothane

- dosed pregnant rats, but no fetal effects were observed (Ghantous et al. 1986, as cit ed in Boutonnet et al. 1999). TFA has also been identified in the milk of lactating rats (5

- 23% following saponification) after the administration of HCFC

- 123 (Buschmann 1996, as cited in Boutonnet et al. 1999). TFA has also been reported to be non

- mutag enic in bacterial studies (Blake et al. 1981 and Waskell 1978, both cited in Boutonnet et al. 1999); studies have not been conducted to determine its carcinogenic potential.

### TFA Assessment

9 

## 4. Assessment of Potential HFO

- 1234yf Emissions and TFA Production

This analysis i s intended as a screening exercise to develop a reasonable worst

- case estimate of HFO

1234yf emissions and the associated production of TFA under various use scenarios. The remainder of this section describes the assumptions used for this analysis to deter mine potential emissions of HFO

1234yf and the expected resultant production of TFA. A discussion on the limitations of the emission projections of HFO

- 1234yf can be found in section 5.3.1 of this paper.



### 4.1. Scenarios of HFO

- 1234y f Market Penetration

For this analysis, two scenarios were developed. These scenarios provide reasonable worst

- case assumptions for the potential market penetration of HFO

- 1234yf in the domestic market only. Both
scenarios assume that HFO

- 1234yf is used as a drop

- in replacement for HFC

- 134a, 3 with a replacement
ratio of 1:1 HFC

- 134a to HFO

- 1234yf. 4

 Scenario 1: HFO

- 1234yf is used in the United States as a new car refrigerant in the MVAC sector.

HFO

- 1234yf begins penetrating the market in 2016 reaching 100 percent market penetration by 2020, as described in Table 3 below.

 Scenario 2: HFO

- 1234yf is used in the United States as a new car refrigerant in MVAC systems, refrigeration, and stationary AC systems. Similar to scenario 1 , by 2020, HFO

- 1234yf is used in all new MVAC systems. For refrigeration and stationary AC systems, HFO

- 1234yf enters the market in 2010, reaches 30 percent penetration of the market in 2015, and 100 percent by 2020.

The scenarios are summarized in Table 3 below.

Table 3 : Summary of Assumed Penetration of HFO1234yf in Scenarios Used in Analysis Sectors 2010 2015 2020
Scenario 1
MVACs 0% 0 % 100% Scenario 2
MVACs 0% 0 % 100% Refrigeration 6% 30% 100%
Sta tionary Air Conditioning 6% 30% 100%



### 4.2. Estimated Emissions of HFO

- 1234yf

Using EPA’s Vintaging Model, ICF estimated emissions of HFO

- 1234yf for both scenarios. These

estimates are summarized in Table 4 . A complete table with es timated annual emissions can be found

in Annex A. Figure 1 and Figure 2 graphically depict the estimated HFO

- 1234yf emissions for each

scenario.

3 In all scenarios, HFO

- 1234yf replaces only pure HFC

- 134a, not any blends with HFC

- 134a as a component.

4 The ratio of HFC

- 134a to HFO

- 1234yf has been estimated at 1:0.9, however a 1:1 ratio was used to provide a

worst case estimate

.

### TFA Assessment

10 Table 4 : Summary of Estimated Emissions of HFO

- 1234yf (MT)* Scenarios 20 20 20 3 0 20 40 2 0 5 0 Scenario 1 6,244 28,327 33,196 36,478 Scenario 2 1 0,345 42,800 55,349 64,324

* ICF projected emissions of HFO

- 1234yf using special scenarios designed specifically for this analysis and run on
the U.S. EPA Vintaging Model, Version VM IO File v4.1 5

- 1 9

- 0 9

.

Figure 1 : Estimated Emissions of HFO

- 1234yf under Scenario 1 (MT)

### TFA Assessment

11 Figure 2 : Estimated Emissions of HFO

- 1234yf under Scenario 2, by End

- Use Sector (MT)



### 4.3. Estimated Production of TFA

The production of TFA from HFO

- 1234yf emissions was estimated under the assumption that 90 percent
of HFO

- 1234yf emissions degrade to TFA. These estimates are summarized in Table 5 below. A complete table with estimated annual TFA production can be found in Annex B.

Table 5 : Summary of Estimated Production of TFA (MT) Scenarios 20 20 20 30 20 40 20 5 0 Scenario 1 5,620 25,494 29,877 32,830 Scenario 2 9,311 38,520 49,814 57,892

### TFA Assessment

12 

## 5. Assessment of Potent ial Impacts of HFO

- 1234yf and TFA

Th is section uses the projected emissions of HFO

- 1234yf under scenario 2 described in section 4 to predict a reasonable worst case scenario leading to impacts on aquatic communities , soil and p lants, and local air quality. For all analyses, emissions of refrigerant due to servicing motor vehicle air conditioning systems were expected to be higher during the spring and summer, with up to 80% of emissions due to repairs occurring from April throu gh August. 5 Furthermore, refrigerant emissions from servicing motor vehicle air conditioning systems were estimated at 47% of annual refrigerant emissions from motor
vehicles. 6 As a result, the analysis assumes that 59.5% of annual emissions of HFO

- 1234y f would occur from April through August, with 11.9% of annual emissions occurring during each of those five months. The remaining 40.5% of annual emissions was modeled to occur from September through March, with 5.8% of annual emissions occurring during e ach of those seven months. This assumption was also applied to stationary AC end uses based on the assumption that similar patterns of seasonal emissions
would be attributable to this end

- use.

The analysis and discussion included in this section are descr ibed as follows.

 Section 5.1 analyzes impacts on aquatic communities, soil, and plants using l ocalized modeling
that was undertaken for both the Houston region and the South Coast Air Basin region of the
United States. These areas were chosen based on the potential presence of vernal pools and their susceptibility to high TFA deposition concentrations.

 Section 5.2 analyzes local air quality impacts using scaling rations based on VOC emission
increases for both the Houston

- Galveston region and the South Coast Air Basin. These areas were chosen based on their projected dates for reaching ozone attainment which coincide with the large increase in HFO

- 1234yf emission rates.

 Section 5.3 discusses the limitations and uncertainties related to the modeling a nd analysis
conducted for this assessment.



### 5.1. Aquatic and Soil Impacts

The general approach to analyze the potential impacts of HFO

- 1234yf emissions on water, soil, and plants involved modeling emissions of SO 2 that were scaled proportionately to the project ed emissions
of HFO

- 1234yf from scenario 2

. For example, if SO 2 emissions are ten tons per day in a given location and for the same geographical region HFO

- 1234yf emissions are projected to be one ton per day, then the resulting modeled concentration woul d be reduced by a factor of ten. The assumption that SO 2 can be scaled proportionately to HFO

- 1234yf is made based on the understanding that the lifetime cycle for

SO 2 to sulfate conversion and their removal in cloud droplets is similar to that of HFO

- 1234 yf to TFA removal in cloud droplets. Further, the conversion of SO 2 to sulfate is also a reasonable proxy for the
conversion of HFO

- 1234yf to TFA because both processes have atmospheric lifetimes of a few days, compared to the much longer atmospheric life time of HFC

- 134a of 14 years.

In the paper by Papadimitriou et al. (2007) the authors demonstrated that the local lifetime for HFO

-

5 Hoffpauir, Elvis. 2009. Email to Karen Thundiyil, 10 March.

6 U.S. EPA Vintaging Model, Version VM IO File v4.2 10

- 07

- 08

### TFA Assessment

13 1234yf was ~ 6.6 days based on typical concentration levels of OH and Cl in a non

- marine environment. Further, the Cl atom abundance is expected to be higher in the marine boundary layer leading to an
even shorter lifetime (on the order of a few days) as typical for Los Angeles and Houston. The major product from HFO

- 1234yf degradation is CF 3 CFO which through hydrolysis in cl oud droplets will lead to the formation of TFA in ~ 5 days. Emissions of SO 2 are converted to the sulfate aerosol within clouds by
oxidation from ozone and OH

- molecules. Once in the form of a sulfate aerosol it is removed by water droplets. This proce ss has a typical lifetime on the order of ~ 7 days (Lohmann et al., 1999), but is more rapid in urban environments with higher background levels of OH

- and ozone.

Thus, to a first approximation the SO 2 to sulfate removal is of a similar time period as t he HFO

- 1234yf to
TFA removal with a similar removal process (wet deposition). Thus, the conversion of SO 2 to sulfate is a reasonable proxy for the conversion of HFO

- 1234yf to TFA because both processes have similar atmospheric lifetimes and final removal processes.

EPA’s three

- dimensional community multiscale air quality model (CMAQ) was applied using emissions of

SO 2 only from Los Angeles and Houston to determine the dry sulfate deposition and sulfate rainwater concentrations for a typical one

- year (2001) period using hourly meteorological data. 7 The sulfate concentrations were then scaled on a emissions molar adjusted basis to estimate the maximum potential concentration of TFA in rainwater and dry deposition both on an annual basis

, as well as for
the maximum month downwind deposition for both Houston and Los Angeles

. To account for the minor difference in lifetime for sulfate and for TFA (3 days vs. 5 days) due to in

- cloud removal, a log

- log adjustment was also made to the output of the model to estim ate TFA concentrations in rainwater.



### 5.1.1. Wet Deposition

Estimates were made for both the dry deposition pathway

, as well as the wet deposition pathway. The results of the maximum monthly and annual average TFA concentration in rainwater are presented in
Table 6 for both Houston and Los Angeles.

Table 6 : Estimated Maximum Annual Average TFA and Monthly Maximum TFA Concentration in Rainwater (mg/L)

Year HFO

- 1234yf

Emissions Los Angeles (MT / yr ) HFO

- 1234yf

Emissions Houston (MT /yr ) Maximum

Monthly Average Downwind of Los Angel e s a Maximum

Monthly Average Downwind of Houston b Maximum Annual

Average Downwind of Los Angeles Maximum Annual

Average Downwind of Houston
2015 63 16 0.02 0.0001 0.00 0.0001
2020 767 191 0.29 0.0013 0.05 0.0009
2025 1,926 481 0.74 0.0034 0.12 0.0022
2030 3,365 840 1.23 0.0055 0.21 0.0038
2040 4,101 1,023 1.57 0.0071 0.25 0.0046
2050 4,766 1,189 1.80 0.0081 0.29 0.0053

a Maximum concentration occurred in July

b Ma ximum concentration occurred in April but July was close to April values

7 More information is available on the CMAQ model at http://cmascenter.org/

.

### TFA Assessment

14 For the Los Angeles region , modeled concentrations of TFA in rainwater are expected to be highest during the month of July due to the relatively high concentration of the hydroxyl (O H) radicals in the atmosphere during the summer as well as limited rainfall. The high concentration of OH allows more

HFO

- 1234yf to react yielding a higher production rate. In addition, the low rainfall rate limits dilution and allows for a higher conce ntration of TFA in rainwater when it does rain occasionally during the summer season in the San Gabriel Mountains to the east of Los Angeles.

Compared to Los Angeles, the precipitation rates in the Gulf Coast region are expected to be much higher and mo re widely distributed in the summer allowing TFA to be more diluted. Furthermore, the availability of OH radical is likely lower in Houston due to more frequent cloud cover. As a result, the monthly maximum TFA concentration in Houston

, which occurs in April with a slightly lower value occurring in July, is lower than Los Angeles. On an annual basis the maximum TFA rainfall concentration is also considerably lower in Houston than Los Angeles.

The potential for accumulation of TFA in aquatic environme nts is greatest for closed aquatic systems over multiple years. These types of closed aquatic systems are predominately found in two regions of the United States; the glaciated region of eastern North America, which includes 1) the Great Lakes
Basin and N ew England, and 2) California and Nevada. Therefore, the Los Angeles regional assessment has the potential for maximum annual TFA impact.

The highest monthly average TFA concentration in rainwater is estimated to be 1 .8 mg/L in 2050 located
downwind of Los Angeles, while the monthly maximum concentration downwind of Houston is estimated to be only 0.0 0 8 mg/L. The maximum concentrations in both annual and monthly rainwater
for Houston are well below the 0.12 m g/L no observed effect concentration (NOEC) reported for the most sensitive freshwater green algae species tested to date. However, Los Angeles shows the potential for concentrations to exceed the no effect levels for this algae species starting in 20 20 for the monthly maximum concentration and 20 2 5 for the annual average maximum. If the NOEC levels are exceeded, sensitive algae species may suffer decline. Note however, all other plant or microbes exhibited no effects for the maximum modeled TFA concentrations for both the monthly and annual

aver age concentrations.

In section 3.1 of this paper, it was concluded that the NOEC is 10 mg/L for vernal pool microbial species and 1 mg/L for vernal pool plant species. Thus beginning sometime between 2025 and 2030 the potential exists for rainwater con centrations to exceed NOECs in vernal pools near Los Angeles during the month of July , which represents the monthly maximum concentration

. However, the maximum annual average of 0. 29 mg/L in rainwater downwind of Los Angeles in 2050 and both the maximum

a nnual and monthly averages for Houston remain significantly below the NOECs for all vernal pool species. Environmental sinks (e.g., adsorption to soil) may further affect the bioavailability of localized TFA concentrations such that they could potentially be below the NOEC for both plants and microbes.

NOECs were compared to rainwater TFA concentrations because for most water bodies, it is difficult to predict what the actual TFA concentration will be. This is because concentrations of environmental

c ontaminants in most fresh water bodies fluctuate widely due to varying inputs and outputs to most ponds, lakes, and streams. Comparison of NOECs to rainwater concentrations of TFA is actually more conservative because TFA is expected to be diluted in mo st freshwater bodies. The exception to this is

### TFA Assessment

15 vernal pools and similar seasonal water bodies that have no significant outflow capacity. These are
discussed in more detail in the next section.



### 5.1.2. Dry Deposition

The amount of dry deposition was determined assuming a constant deposition velocity for TFA of 1.15 cm/s based on the average depo sition rate of 0.88 cm/s for urban

- night s, 2.03 cm/s for urban

- day s, 1.00 cm/s for desert

- day s, and 0.7 cm/s for desert night s ( Zhang, L., J. R. Brook, and R. Vet 2003)

. Table 7 presents the results of the maximum annual and monthly TFA deposition.

Table 7 : Estimated Maximum Annual (nmole/m 2/ /yr) Dry Deposition of TFA and Monthly (nmole/m 2 / yr) Maximum Dry Deposition

Year HFO

- 1234yf Emissions Los Angeles(MT /yr ) HFO

- 1234yf

Emissions Houston (MT /yr ) Maximum

Monthly Average Downwind of Los Angel es a Maximum

Monthly Average Downwind of Houston b Maximum Annual

Average Downwind of Los Angels Maximum Annual

Average Downwind of Houston
2015 63 16 1,864 69 454 9
2020 767 191 27,241 1,012 5,537 111
2025 1,926 481 69,250 2,571 13,912 279
2030 3,365 840 114,559 4,254 24,308 488
2040 4,101 1,023 146,107 5,425 29,625 594
2050 4,766 1,189 167,892 6,234 34,429 691

a Maximum con centration occurred in March

b Maximum concentration occurred in July

Results show that the monthly peak dry deposition occurs in March for Los Angeles and in July for Houston. In Los Angeles, the results also indicate that the deposition is closer to t he source region in March. This is likely due to lower wind speeds which yield less dispersion as compared to the summer months, although there the difference in the peak monthly average concentration between March and May

– October is small

.

Dry depo sition of TFA is likely more of a concern in central and southern California than is wet deposition due to the lower rainfall in the state compared to other geographical areas of the United States. A comparison of dry deposition rates modeled for areas do wnwind of Los Angeles is presented

in Table 8 , along with measured TFA flux rates from two vernal pool systems outside of Sacramento, California (Cahill et al. 2001; data taken in 1998 and 1999).

The values above indicate that projected maximum annual average deposition of TFA will be greater
after 2015 than what has been measured in vernal pools in the last decade in Northern California. We would expect measured values in vernal pools in Southern California to b e somewhat higher owing to
the reduced rainfall. These projected deposition levels are consistent with the higher localized production of TFA from the use of HFO

- 1234yf. Future TFA loading in seasonal wetlands are predicted
to increase with increased use of HFO

- 1234yf. It is difficult to predict at this point whether the increased levels will be harmful to typical obligate species in these wetlands, such as fairy and tadpole shrimp.

### TFA Assessment

16 Table 8 : Future Year(s) Modeled Dry Deposition of TFA a Downwind of Los Angeles and Comparison to TFA Measurements in California Vernal Pools, 1998

- 1999

Modeled Year Maximum Average Yearly Deposition Observed Year Values measured in CA vernal pools

nmole/m2

- yr  g/m2

- yr ng/m2

- day  g/m2

- yr 2015 454 52 1998

- 1999 134* 48.9
2020 5,537 633 1998

- 1999 110** 40. 2 2025 13,912 1

, 590 1998

- 1999 152*** 55. 5 2030 24,308 2

, 778
2040 29,625 3

, 386
2050 34,429 3

, 935

a Based on HFO1234yf Scenario 2 emission rates (see section 4.1)

Notes: Formula weight o f TFA is 114 g/mole.
*Time

- weighted average of values measured in Davis, CA Jan 1

- May 16, 1998.
**Time

- weighted average of values measured in Davis, CA Nov 26, 1998

- Apr 2, 1999.
***Time

- weighted average of values measured in Yolo Country Grasslands Regiona l Park, CA Jan 6

- May 6, 1999.
Values of  g/m2

- yr

– ng/m2

- day * 365 days/1000



### 5.2. Air Quality Impacts

Increase in ground level ozone is a nother potential impact of using HFO

- 1234yf. The potential for ozone
creation from the release of HFO

- 1234yf is expected to be similar to the volatile organic compound (VOC)

– ethylene (Papadimitriou, V. et al, 2007). This fairly reactive compound VOC is an important ozone precursor especially in rich NO x environments where the addition of VOC will act linearly to

increase ground level ozone.

The Houston

- Galveston region and the South Coast Air Basin in California are areas where high levels of ground level ozone have been a continuin g and chronic problem. These two regions were examined to analyze the potential impacts o f using HFO

- 1234yf on ground level ozone, assuming business as usual
emissions of NO x and VOC. For Houston, data were taken from the Post

- 1999 Rate of Progress and Attainment Demonstration SIP to predict future emissions of NO x and VOC (Texas Natural Reso urce Commission, 2000) up to the 2019 ozone attainment year based on model simulations during the

summer ozone season

. Data for the South Coast region were taken from the 2007 Air Quality Plan, which predicts future emissions of NO x and VOC for attaining the ozone standards for 2017 and 2023 (South Coast, 2007), again based on modeling during the summer ozone season.

Data for f uture year projections after 20 23 for both Houston

- Galveston and the South Coast were estimated based on a need for continued red uction in emissions due to increased temperatures from global warming. Climate change impacts reported in the IPCC’s 4 th A ssessment R eport (IPCC, 2007) predict that by 2050 global warming will increase average daily ozone levels across the eastern U.S. by 3.7 ppb based on likely emission levels . It is assumed that the regional air quality plan would be adjusted accordingly to compensate for this expected increase. T hus

, the Houston

- Galveston regional

emissions of both NO x and VOCs were proportionately re duced to maintain attainment of the current 8

-

### TFA Assessment

17 hour ground level ozone standard of 75 ppb. 8 While less specific data is available for the South Coast, IPCC projections report significant increase in the frequency and magnitude of ground level
temperature, which leads to higher ozone concentrations. Thus, it is assumed that the same level of increase in background ozone concentration would be seen for the South Coast region as projected for the eastern United States. As a result, regional emissions for the South Coast after 2023 were also proportionately reduced to account for the expected 3.7 ppb increase.

Data from scenario 2 (described above in Table 3 ) were used to project the amount of HFO

- 1234yf (metric tons, MT, per day) emi tted in the Houston

- Galveston and South Coast regions. The annual output shown in Annex A was adjusted according to the population of the Houston

- Galveston and South Coast regions . Emissions from the MVAC and stationary AC end uses were multiplied by 59.5 % and then divided by 153 days/year (number of days in the summer ozone season) to determine the higher summer seasonal daily emission rate for HFO

- 1234yf. 9 Refrigeration emissions were assumed to be uniformly distributed throughout the year. These data were then used to make two sets of projections concerning the production of ground level ozone. One set of projections assumes the reactivity of HFO

1234yf to be the same as the average VOC . The other set of projections assumes HFO

- 1234yf is more

reactiv e and has the maximum potential to form up to 3 molecules of ozone per molecule of HFO

1234yf. 10 This assumption implies that one tonne of HFO

- 1234yf emissions has an equivalent impact on air quality as 3 tonnes of emissions of average VOC.

The emission projections of NOx, VOC, and HFO

- 1234yf in the Houston

- Galveston and South Coast region are summarized in Table 10 an d Table 11.

Table 10: Projected Emissions of NOx, VOC, and HFO

- 1234yf in the Houston

- Galveston region of Texas (MT/day)
Year NOx VOC HFO

- 12 34yf 3x HFO

- 123 4 yf
2019 764 378 0.4 7 1.41
2029 753 373 2.61 7.84
2040 741 367 3.59 10.78
2050 730 362 4.13 12.38 Source: Post

- 1999 Rate

- of

- Progress and Attainment Demonstration SIP for the Houston/Galveston Ozone Nonattainment Area (Texas Natural Res ource Conservation Commission, 200 0 )

* Includes the counties of Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery and Waller

8 For both Houston and Los Angeles the ozone attainment demonstrations emission reductions were based on the prior 80 ppb 8

- hour ozone standard. Additional emission reductions will be needed to reach the new 75 ppb 8

- hour standard. It is assumed that a linear reduc tion for both VOC and NO x would be needed to reach this new standard and impacts of HFO

- 1234yf were evaluated based on these lower emission rates.

9 Hoffpauir, Elvis. 2009. Ema il to Karen Thundiyil, 10 March; U.S. EPA Vintaging Model, Version VM IO Fil e v4.2 10

- 07

- 08

10 In discussions with Dr. Ravishankara

, the director of the Chemical Sciences Division of the National Oceanic and Atmospheric Administration ( NOAA ) Earth System Research Laboratory in Boulder, Colorado, it was indicated that

HFO

- 1234yf has the potential to form up to 3 molecules of ozone per molecule of HFO

- 1234yf reacted hydroxyl
radical.

### TFA Assessment

18 Table 11: Projected Emissions of NOx, VOC, and HFO

- 1234yf in the South Coast* region of California (MT/day)
Year NOx VOC HFO

- 1234yf 3x HFO

- 123 4 yf
2017 335 392 0.73 2.19
2023 280 355 5.14 15.41
2040 272 345 14.40 43.19
2050 268 339 16.54 49.63 Source: South Coast AQMD 2007 Future Year Emission Inventory (South Coast, 2007)

* Includes the counties of Kern, Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Luis Obispo, San Diego, Santa Barbra and Ventura

For Houston

- Galveston t he ratio of the 3x HFO

- 1234yf to the 2019 VOC emission rate shows that ground level ozone potentia lly could increase by less than 1 % (0. 37 %= 1.41 /378) assuming a VOC

- limited

environment , or an environment where ozone formation is limited by the availability of VOC (not the availability of NOx)

. However, if the reactivity of HFO

- 1234yf is assumed to be the same as the avera ge VOC (as opposed to forming 3 molecules of ozone per molecule of HFO

- 1234yf), it is predicted that ground level ozone would increase by an even lesser percentage (0.1 2 %= 0. 4 7 /378). By 2029, the potential increases in ground level ozone could be as high as 1 %

- 2 % depending on the reactivity of

HFO

- 1234yf.

For the South Coast t he ratio of the 3x HFO

- 1234yf to the 2023 VOC emission rate shows that ground level ozone potentia lly could increase by a bout 4.3 % (= 15.41 /355) assuming a VOC limited

environment

. However, if the reactivity of HFO

- 1234yf is assumed to be the same as the average VOC (as opposed to forming 3 molecules of ozone per molecule of HFO

- 1234yf), then ground level ozone would increase by about 1.4 % (= 5.14 / 355 )

.
These percentage increases i n ozone suggest how much ground level ozone may potentially increase as
a result of the use of HFO

- 1234yf, relative to the projected emissions of NOx and VOC. Both of these regions have detailed plans to achieve attainment of the 8

- hour ozone standard. I n Houston, reaching attainment by 2019 would imply having a maximum 8

- hour ozone concentration of no more than 75 ppb. If HFO

- 1234yf was 3x as reactive as the average VOC, HFO

- 1234yf emissions could potentially
contribute 0. 3 ppb to the regional ozone conc entration by 201 9 . Assuming that the Houston regional plan is set to achieve exactly the 75 ppb 8

- hour ozone concentration standard in 2019, an additional
contribution of 0. 3 ppb to the regional ozone concentration could cause the total concentration to reach

75. 3 ppb, which would be considered non

- attainment. Similarly, for South Coast region, in 2023 HFO

1234yf emissions could contribute 3

. 2 ppb to the regional ozone concentration, if HFO

- 1234yf was 3x as reactive as the average VOC. An additional co ntribution of 3

. 2 ppb could cause the total concentration
to reach 7 8

. 2 ppb, which would be considered non

- attainment.

Emissions of NO x and VOC will likely continue to decrease for both the Houston

- Galveston and the South Coast area, 11 and HFO

- 1234yf emis sions are projected to increase (see Annex A), but it is uncertain to what extent these combined changes will impact local air quality in years after 2030. There is the potential for continued increases in ground level ozone from increases in both backgr ound
concentrations and from the contribution from HFO

- 1234yf emissions and other VOC emissions sources; however, uncertainties related to the impacts from global warming, changes in control technology, and

11 South Coast AQMD 2007 Future Year Emission Inventory (South Coast, 2007); Post

- 1999 Rate

- of

- Progress and Attainment Demonstration SIP for the Houston/ Galveston Ozone Nonattainment Area (Texas Natural Resource Conservation Commission, 2000).

### TFA Assessment

19 changes in emission sources do not allow a detai led analysis to be conducted at this time. Additionally, it is expected that air quality planners in regions such as Houston and the South Coast would seek to offset significant emission increases of HFO

- 1234yf with emissions reductions from other VOC so urce categories. Even so, depending upon the spatial and temporal distribution of HFO

- 1234yf emissions, there is potential that these emissions could contribute to the production of ground level ozone and potentially contribute to non

- attainment or exacer bate existing non

- attainment in a given region.

For other areas of the United States that were not examined in this analysis, a similar conclusion can be
drawn: HFO

- 1234yf emissions have the potential to increase ground level ozone; however, the percent

in crease of 1%

– 4 % is not expected to impact other regions as severely. Most other areas are not VOC

limited meaning that their ozone concentrations are not affected by additional VOC emissions. Furthermore, it is expected that less severe regions will ach ieve the ozone standard by 2013, 12 thus retaining some additional margin of safety. Because the two regions, Los Angeles and Houston, are expected to reach attainment coincident with the rapid market penetration of HFO

- 1234yf in the late 2010’s, these two regions are representative of those most susceptible to being pushed backed into

non

- attainment as a result of ozone formation from HFO

- 1234yf emissions.



### 5.3. Limitations of this Analysis

The analysis described above is based on numerous assumptions and projec tions that cannot be known with certainty at this time. The following discussion recognizes these uncertainties and indicates various factors that have potential to impact and change the results of this analysis.



### 5.3.1. Market Modeling

 The market penetration as sumptions used for this analysis assume HFO

- 1234yf will be the sole replacement for HFC

- 134a. However, the introduction of additional substitutes could potentially lower the penetration of HFO

- 1234yf into the market, thus decreasing the emissions and impa cts of HFO

- 1234yf and TFA.

 Even though EPA’s Vintaging Model, used to calculate emissions for both scenarios, provides output up to 2050, the assumptions used in the model are based only on current data and expert opinions regarding the near future. Sinc e it is not possible to predict with certainty changes that will occur in the distant future (post 2020), the assumptions in the model are not adjusted for additional unpredictable cha nges that will likely take place.

 EPA’s Vintaging Model does not account for reductions in emissions that may occur as a result of using HFO

- 1234yf as a replacement for HFC

- 134a. Factors such as refrigerant price and
advancements in leak

- tightness of MVAC systems are not adjusted for in the modeling. Consequently, HFO

- 1234yf emission projections are considered to be conservative.



### 5.3.2. Aquatic and Soil Impacts

12 Environmental Protection Agency. Accessed May 2009. Classifications of 8

- Hour Ozone Nonattainment Areas. Last Updated March 12, 2009. Available at < http://www.epa .gov/air/oaqps/greenbk/gnc.html >

### TFA Assessment

20  The modeling of potential future impacts to plant and animal species adapted to vernal pool ecology may be overestimated using the models described. This is due to human pop ulation differences in the area of southern CA, which is modeled in section 5.1, to the populations currently living in the areas known to have recurrent vernal pools (e.g., Central Valley of CA). Nevertheless, it is important to assume maximum impact bas ed on emissions modeling due to the persistent nature of TFA in the environment.

 A significant source of uncertainty in the analysis of aquatic toxicity is the receptor species used in the analysis. For example, in the cited studies, researchers used wi dely accepted and standardized species of freshwater flora and fauna. These plant and animal species, however, are not typical of specialized vernal pool species in California such as meadow foam, Downingia, Navarettia, fairy shrimp, tadpole shrimp, or ti ger salamanders. Of course, one reason for this is that many of these species are endangered and/or protected, and it is not possible to conduct toxicity studies on them. Nevertheless, lack of knowledge regarding the susceptibility and/or

resistance to T FA or similar compounds by these species affects the ability to more accurately quantify aquatic impacts from TFA deposition in certain geographical areas.

 T he ecology considered in this analysis is a highly specialized one that is vital to many species,

i ncluding migratory birds. In addition, regional areas that contain the geology necessary for vernal pool formation are subject to modification via many means, including residential and commercial development, mining, agriculture, and in California, earthq uakes. These activities also produce environmental contamination that affects species adapted to vernal pool ecology. It is not possible to predict the impact of these external effects on aquatic toxicity of vernal pools, nor how TFA concentrations, in c oncert with these other effects, might change the estimated results presented here.



### 5.3.3. Air Quality

 Improvements in the understanding of the reactivity of HFO

- 1234yf and resulting production of TFA and ozone formation are likely to change the estimates made i n this analysis.

 Further global warming impacts will result in region

- specific changes that may for example increase local cloud cover leading to decreases in local photolysis rates resulting in reduced ozone production.

 The changes in standards for other pollutants such as air toxics or criteria pollutants could effect the precursor ozone emissions. For example, EPA recently announced a proposed rule for a new

1

- hour NO 2 standard in the range between 80 to 100 ppb. In order to meet this standard, signif icant NO x emission reductions may be required, thus impacting the potential production of ground level ozone.

 The ozone air quality standard may be lowered in the future (historically the standard has been lowered a number of times) and would require addit ional reductions of ozone precursor emissions, which would increase the importance of HFO

- 1234yf to the production rate for

ozone.

### TFA Assessment

21 

## 6. Conclusion

From the analysis summarized in the previous sections of this white paper, the following preliminary
conclusions concerning the potential impacts of HFO

- 1234yf and the associated production of TFA can
be made:

 Projected levels of TFA in rainwater should not result in a significant risk of ecotoxicity. After taking into account the nature of HFO

- 1234yf degradation an d the resulting TFA concentration in

rainwater ; regional precipitation patterns; the geology of closed aquatic systems ; and no observed effect concentrations (NOEC) for TFA, TFA production resulting from HFO

- 1234yf emissions is not expected to pose signifi cant harm to aquatic communities in the near future. Future research is necessary to determine if significant TFA loading is occurring in vernal pools near major population centers as there are insufficient data to determine whether TFA would impact these environments significantly.

 Dry Deposition is somewhat of a concern however more research is needed to fully understand the impacts of dry deposition on soil, plants, and aquatic communities. Only two studies were identified which investigated the effects of dry deposition in plants. While one study showed measured effects on photosynthesis, the other did not. It is unclear what impact current and future loading of TFA will have in vernal pool ecosystems. Current tests on freshwater plants and animal sp ecies that might be found in vernal pools show that only one species of algae might be affected at predicted concentrations of deposited TFA. Howe ver, it is not possible to know without further research, whether increased TFA loading might affect other ob ligate vernal pool species.

 Non

- attainment resulting from HFO

- 1234yf emissions is not likely to be a major concern for local air quality in most locations. HFO

- 1234yf could potentially increase ground level ozone by

1 % to 4 % o n a given day in the most extreme case. However, in most cases this upper bound
level of increase is not likely, as most ozone nonattainment areas are (1) not VOC limited and (2)
the HFO

- 1234yf

- mediated ozone production is more likely to be closer to a single molecule
rather than conservative 3 molecules used in this assessment. Both of these conditions would reduce the potential increase in ground level ozone to at most a 1% to 2% increase. However, given the variety of uncertainties, it is difficult to predict how future TFA e missions will impact

non

- attainment of the ozone NAAQS on these days. These uncertainties include the composition of the future atmosphere, the extent of increases or decreases in ground level ozone from other sources, the reactivity of HFO

- 1234yf under n ear

- and later

- term atmospheric conditions, impacts on reactivity and circulation associated with global warming, and, most importantly, the
future measures that may be taken to reduce ozone precursors

.

### TFA Assessment

22 

## 7. References

1234yf OEM Group. 2008. MAC Summit 2008. Available at

< http://www.epa.gov/cppd/mac/HFO1234YF%20EXPERT%20CONSENSUS%20GROUP.ppt >

Abstracts : South African Association of Botanists

– Annual meeting 2006

. South African Journal of Botany 72 : 313

- 347

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### TFA Assessment

25 

## Annex A: Annu al HFO

- 1234yf Emissions Estimated under each Scenario for the Years 2010 through 205 0 (MT)*

Year Scenario 1 Scenario 2

MVACs MVACs Refrigeration Stationary AC TOTAL

2010

- - 31 6 37

2011

- - 96 18 114

2012

- - 194 37 231

2013

- - 329 62 392

2014

- - 502 94 597

2015

- - 715 134 849

2016 407 407 1,034 192 1,633

2017 1,229 1,229 1,465 269 2,963

2018 2,472 2,472 2,014 365 4,851

2019 4,143 4,143 2,685 481 7,309

2020 6,244 6,244 3,484 617 10,345

2021 8,332 8,332 4,304 761 13,397

2022 10,413 10,413 5,169 910 16,493

2023 12,513 12,513 6,031 1,061 19,605

2024 14,644 14,644 6,926 1,212 22,782

2025 16,812 16,812 7,817 1,363 25,992

2026 19,003 19,003 8,702 1,512 29,217

2027 21,203 21,203 9,580 1,675 32,457

2028 23,962 23,962 10,505 1,845 36,313

202 9 26,335 26,335 11,373 2,014 39,722

2030 28,327 28,327 12,261 2,212 42,800

2031 29,927 29,927 13,084 2,405 45,415

2032 31,121 31,121 13,836 2,571 47,529

2033 31,301 31,301 14,420 2,716 48,437

2034 31,526 31,526 15,013 2,860 49,398

2035 31,811 31,811 15,509 3,009 50,328

2036 32,114 32,114 16,040 3,212 51,366

2037 32,418 32,418 16,576 3,408 52,402

2038 32,687 32,687 17,118 3,594 53,399

2039 32,936 32,936 17,664 3,770 54,371

2040 33,196 33,196 18,216 3,936 55,349

2041 33,476 33,476 18,731 4,014 56, 221

2042 33,801 33,801 19,245 4,087 57,133

### TFA Assessment

26 Year Scenario 1 Scenario 2

MVACs MVACs Refrigeration Stationary AC TOTAL

2043 34,110 34,110 19,758 4,160 58,028

2044 34,425 34,425 20,269 4,228 58,922

2045 34,748 34,748 20,779 4,290 59,818

2046 35,079 35,079 21,274 4,329 60,682

2047 35,417 35,417 21,781 4,367 61,565

2048 35,763 35,763 22,301 4,400 62,464

2049 36,116 36,116 22,834 4,433 63,383

2050 36,478 36,478 23,379 4,467 64,324

* ICF projected emissions of HFO

- 1234yf using special scenarios designed specifically for this analysis and run on
the U.S. EPA Vintaging Model, Ve rsion VM IO file v4.1 5

- 19

- 0 9

.

### TFA Assessment

27 

## Annex B : Estimated Production of TFA under each Scenario, by year (MT)

Year Scenario 1 Scenario 2

MVACs MVACs Refrigeration Stationary AC TOTAL

2010

- - 28 5 34

2011

- - 86 16 103

2012

- - 175 33 208

2013

- - 297 56 353

2014

- - 452 85 537

2015

- - 643 120 764

2016 366 366 931 173 1,469

2017 1,106 1,106 1,319 242 2,667

2018 2,225 2,225 1,812 329 4,366

2019 3,729 3,729 2,416 433 6,578

2020 5,620 5,620 3,136 555 9,311

2021 7,499 7,499 3,873 685 12,057

2022 9 ,372 9,372 4,652 819 14,843

2023 11,262 11,262 5,428 955 17,645

2024 13,180 13,180 6,234 1,090 20,504

2025 15,131 15,131 7,035 1,227 23,393

2026 17,103 17,103 7,831 1,361 26,295

2027 19,083 19,083 8,622 1,507 29,212

2028 21,566 21,566 9,455 1,661 32, 681

2029 23,702 23,702 10,235 1,813 35,750

2030 25,494 25,494 11,035 1,991 38,520

2031 26,934 26,934 11,775 2,164 40,874

2032 28,009 28,009 12,453 2,314 42,776

2033 28,171 28,171 12,978 2,444 43,593

2034 28,373 28,373 13,511 2,574 44,458

2035 28,630 28,630 13,958 2,708 45,295

2036 28,902 28,902 14,436 2,891 46,229

2037 29,176 29,176 14,918 3,068 47,162

2038 29,418 29,418 15,406 3,235 48,059

2039 29,643 29,643 15,898 3,393 48,934

2040 29,877 29,877 16,395 3,543 49,814

2041 30,129 30,129 16,858 3 ,613 50,599

2042 30,421 30,421 17,320 3,679 51,420

2043 30,699 30,699 17,782 3,744 52,225

### TFA Assessment

28 Year Scenario 1 Scenario 2

MVACs MVACs Refrigeration Stationary AC TOTAL

2044 30,983 30,983 18,243 3,805 53,030

2045 31,273 31,273 18,701 3,861 53,836

2046 31,571 31,571 19,147 3,896 54,614

2047 31,875 31,875 19,603 3,930 55,409

204 8 32,186 32,186 20,071 3,960 56,217

2049 32,505 32,505 20,550 3,990 57,045

2050 32,830 32,830 21,042 4,020 57,892