**SNAP TECHNICAL BACKGROUND DOCUMENT: RISK SCREEN ON THE USE OF**  **SUBSTITUTES FOR CLASS I OZONE**  **- DEPLETING SUBSTANCES:**  **REFRIGERATION AND AIR CONDITIONING**

U.S. Environmental Protection Agency Office of Air and Radiation Stratospheric Protection Division Mail Code 6205J 401 M Street, S.W. Washington, D.C. 2 0460

March 1994ii **NOTICE** This background document supports the U.S. Environmental Protection Agency 's (EPA) rulemaking for controlling the replacement of Class I ozone - depleting substances (ODSs) with an y substitute that presents unacceptable risk to human health or the environment where safer alternatives are available. S pecificall y, this document examines the risk from the use of various refrigeration and air conditi oning substitutes. S imilar documents address other industry sectors. IC F Incorporated provided support for the preparation of this document at the technical direction of the Stratospheric Protection Division, Office of Air and Radiation, EPA, Contract No . 68 - D9 - 0068, Work Assignments 3 - 23 and 3 - 69; and Contract No. 68 - C2 - 0107, Work Assignment 39; and Contract No. 68 - D3 - 0021, Work Assignments 1 - 11 and 2 - 18. M eridian Research Incorporated also provided technical support under Contract No. 68 - D9 - 0068, Work Assignment 3 - 68 and Contract No. 68 - D3 - 0021 Work Assignment 2 - 18, particularl y for the occupational evaluation. Z BA, under Work Assignment 3 - 74, provided technical support for evaluating the feasibility

of substitutes.iii **TABLE OF CONTENTS Section**  **Page** Notice ................................ ................................ ................................ ................................ ............. ii Executive Summary ................................ ................................ ................................ ....................... vi ES.1 The Refrigeration and Air Conditioning Sectors ................................ ................... vi ES.2 Risk Screening Methodology ................................ ................................ ............... viii ES.3 Risk Screening Results ................................ ................................ ............................ x 1. IN TRODUCTION ................................ ................................ ................................ ........... 1 - 1 1.1 Background ................................ ................................ ................................ .......... 1 - 1 1.2 Evaluation of Substitutes ................................ ................................ ..................... 1 - 2 1.3 Risk Screening Reports for Refrigeration and Air Conditioning ................................ ................................ ................................ .. 1 - 3 2. OVERVIEW OF SUBSTITUTES AND END USES ................................ ..................... 2 - 1 2.1 End Uses ................................ ................................ ................................ .............. 2 - 1 2.2 Alternative Refrigerants ................................ ................................ ....................... 2 - 2 2.2.1 HCFCs ................................ ................................ ................................ ...... 2 - 2 2.2.2 HFCs ................................ ................................ ................................ ........ 2 - 3 2.2.3 Hydrocarbons ................................ ................................ ........................... 2 - 3 2.2.4 Ammonia ................................ ................................ ................................ .. 2 - 3 2.2.5 Chlorine ................................ ................................ ................................ .... 2 - 3 2.2.6 Potential Substitutes Manufacturers Have Submitted as Confidential Business Information ................................ .......................... 2 - 4 2.3 Alternative Technologies ................................ ................................ ..................... 2 - 4 2.3.1 Absorption Refrigeration Sy stems ................................ ........................... 2 - 4 2.3.2 E vaporative Cooling ................................ ................................ ................ 2 - 4 3. TOXICITY REFERENCE VALUES FOR SUBSTI TUTES ................................ .......... 3 - 1 3.1 Occupational (Inhalation) Exposure L imits ................................ ......................... 3 - 1 3.2 General Population/Consumer (Inhalation) Toxicity Reference Values ............. 3 - 6 3.2.1 Reference Concentrations (RfCs) ................................ ............................ 3 - 6 3.2.2 Cancer Slope Factors ................................ ................................ .............. 3 - 8 Chapter 3 References ................................ ................................ ................................ ....... 3 - 9 4. ATMOSPHERI CS MODELING ................................ ................................ ..................... 4 - 1 4.1 Introduction ................................ ................................ ................................ .......... 4 - 1 4.2 Description of Refrigerator and Air Conditioning End Uses ............................... 4 - 1 4.3 Control Options ................................ ................................ ................................ .... 4 - 4 4.4 The Baseline for the Analy sis ................................ ................................ .............. 4 - 4 4.4.1 Uniform Assumptions Made Throughout the Analy sis ........................... 4 - 4 4.4.2 Assumptions Made for All Other End Uses ................................ ............ 4 - 5 4.4.3 Assumptions Made Within the End Use of Concern ............................... 4 - 5 4.4.3.1 I deal Substitute Baseline ................................ ............................ 4 - 5 4.4.3.2 N o Substitution Baseline ................................ ........................... 4 - 7iv

4.5 Overview of the Modeling Approach ................................ ................................ .. 4 - 8 4.5.1 Chemical Use ................................ ................................ ........................... 4 - 8 4.5.2 Chemical Emissions ................................ ................................ ................. 4 - 8 4.5.3 Atmospheric Effects ................................ ................................ ................. 4 - 8 4.5.4 Human Health Effects ................................ ................................ .............. 4 - 9 4.6 Model Results ................................ ................................ ................................ .... 4 - 10 4.6.1 Description of the Results ................................ ................................ ...... 4 - 10 4.6.2 Interpreting the Results ................................ ................................ .......... 4 - 10 4.7 Global Warming ................................ ................................ ............................... 4 - 92 4.7.1 The Nature of the Global Warming Problem ................................ ......... 4 - 93 4.7.2 Properties of Greenhouse Gases ................................ ............................ 4 - 93 4.7.3 Properties of CFCs and CFC Substitutes ................................ ............... 4 - 95 4.7.4 Indirect Effects from Changes in Energy Efficiency ............................. 4 - 98 4.7.4.1 Refrigeration and Air Conditioning End Uses ........................... 4 - 98 4.7.4.2 Foam Insulation ................................ ................................ ......... 4 - 99 Chapter 4 References ................................ ................................ ................................ ... 4 - 100 5. OCCUPATI ONAL EXPOSURE AND HAZARD ANALYSIS ................................ ..... 5 - 1 5.1 Introduction ................................ ................................ ................................ .......... 5 - 1 5.2 Description of the Model ................................ ................................ ..................... 5 - 1 5.3 Discussion of the Results ................................ ................................ ..................... 5 - 4 5.3.1 Presentation of Results ................................ ................................ ............. 5 - 4 5.3.2 Interpretation and Comparison of Model Results with Sampling Data ... 5 - 5 5.4 Potential Workplace Flammability and Explosivity

Risks ................................ .. 5 - 8 Chapter 5 References ................................ ................................ ................................ ... 5 - 10 6. CONSUMER EXPOSURE AND RI SK SCREENING ANALYSI S .............................. 6 - 1 6.1 Home Appliances ................................ ................................ ................................ . 6 - 2 6.1.1 Risks from L ong - term Exposure t o L eakage and Servicing Events C Previous Estimates ................................ ................................ ................... 6 - 2 6.1.2 Risks form Short - term Exposure During Servicing and Accidental Releases ................................ ................................ ................................ .... 6 - 3 6.1.3 Summary

of Modeling Results ................................ .............................. 6 - 10 6.1.4 Safety

Concerns: H FC - 152a in Household Refrigerators ................... 6 - 10 6.2 Mobile Air Conditioners (MACs) ................................ ................................ ...... 6 - 11 6.2.1 Approach Used in a Previous Consumer Exposure Report ................... 6 - 11 6.2.2 Comparison of Parameters Contained in Consumer Exposure Report with Data from Other Sources ................................ ............................... 6 - 12 6.2.3 Summary ................................ ................................ ................................ 6 - 13 Chapter 6 References ................................ ................................ ................................ ..... 6 - 14 7. GENERAL POPULATION EXPOSURE AND RISK ANALYSIS .............................. 7 - 1 7.1 HCFCs and HFCs ................................ ................................ ................................ 7 - 1 7.1.1 Approach ................................ ................................ ................................ .. 7 - 1 7.1.2 Results ................................ ................................ ................................ ...... 7 - 4 7.1.3 Caveats and Limitations ................................ ................................ ........... 7 - 4 7.1.4 Conclusions ................................ ................................ .............................. 7 - 7 7.2 Other Alternative Refrigerants ................................ ................................ ............. 7 - 7 7.2.1 Background ................................ ................................ .............................. 7 - 8v 7.2.2 Approach ................................ ................................ ................................ .. 7 - 8 7.2.3 Results ................................ ................................ ................................ .... 7 - 9 7.3 Chlorine ................................ ................................ ................................ ................ 7 - 9 7.4 Lithium Bromide and Ammonia in Absorption Systems ................................ .. 7 - 11 Chapter 7 References ................................ ................................ ................................ ..... 7 - 12 Attachment 7 - A: D etailed Categorization of Refrigeration End Uses and

Equipment Ty

pes ................................ ................................ ........... 7 - A - 1 Attachment 7 - B: A ssumptions for Ambient Air Release Cal culations ..................... 7 - B - 1 Attachment 7 - C: M ethodology for Estimating General Population Exposures to Ambient Air Releases of Substitutes for Class ISubstances for SNAP Risk Screens 7 - C - 1 Attachment 7 - D: D etailed Results ................................ ................................ ............. 7 - D - 1 Attachment 7 - E: P ercent of Equipment with Assumed Charge Size ........................ 7 - E - 1 8. VOLATILE ORGANIC COMPOUND ANALYSIS ................................ ...................... 8 - 1 8.1 VOC Emissions from Substitutes to Class IODSs ................................ .............. 8 - 1 8.2 VOC Emissions from All Sources ................................ ................................ ....... 8 - 1 8.3 Comparison of VOCs from Substitutes to VOCs from All Sources .................... 8 - 1 8.4 Caveats and Limitations ................................ ................................ ....................... 8 - 2 Chapter 8 References ................................ ................................ ................................ ....... 8 - 3 Attachment 8 - A: E stimation of Total VOC Emissions from All Sources in 1995 .... 8 - A - 1 Attachment 8 - B: V OC Controls ................................ ................................ ................ 8 - B - 1**EXECUTIVE SUMMARY**

This report presents a screening a ssessment of human health and environmental risks associated with the use of potential substitutes for ozone depleting substances (ODSs) in the refrigeration and air conditioning sectors. 1 ODSs are being phased out of production in response to a series o f diplomatic and legislative efforts that have taken place in the past few years, including the Montreal Protocol and, more recently, the Clean Air Act Amendments of 1990. T he anal ys es presented in this report support the United States Environmental Prote ction Agency's Significant New Alternatives Policy (SNAP) Program, which is authorized by Section 612 of the Clean Air Act Amendments. Implementation of this program involves: (1) developing, promulgating, and administering a regulatory program for identi fying and evaluating substitutes, and (2) publishing a list of acceptable and unacceptable substitutes for specific end uses. The remainder of this summary provides an overview of ODS use in the refrigeration and air conditioning sectors, the methodology used to conduct the risk screen, and the key results. **ES.1 THE REFRIGERATION AND AIR CONDITIONING SECTORS**  ODS use in the refrigeration and air conditioning sectors accounted for almost 22 percent of the total use of Class I s ubstances in the United State s in 1990. C FC - 12 is the most widel y used refrigerant, with applications in mobile air conditioners (MACS), household refrigerators and freezers, various appliances, chillers, retail food refrigeration equipment, cold storage warehouses, refrigerated tran sport s ys tems, and industrial equipment. C FC - 11 is most commonly used to provide cooling for large buildings, while CFC - 115, as a component in the refrigerant blend R - 502, is used for low temperature applications in a variety of sectors. C FC - 113 and CFC - 114 are used in special applications chillers. Of the Class II controlled substances, HCFC - 22 is the refrigerant of choice in small to medium size air conditioning s ys tems, and some ty pes of retail food and industrial process refrigeration s ys tems. EPA h as divided the refrigeration and air conditioning sector into the following general end uses:

 Retail Food Systems : T hese include stand alone refrigeration cases found in small markets, convenience stores, restaurants and other food establishments, large sy stems found in supermarkets, commonl y referred to as parallel s ys tems, and HCFC - 22 sy stems found in a wide variet y of retail and service establishments;

 Cold Storage S ys tems : P ublic and private facilities used to store meat, produce, dairy prod ucts, frozen foods, and other perishable goods. T hese s ys tems refrigerate warehouses of varying sizes and include high pressure and low pressure sy stems;

1 Other ODS sectors evaluated in separate report s are solvent cleaning; foam blowing; fire extinguishing; aerosols; sterilants; and adhesives, coatings, and inks. Chillers : T hese are large commercial air conditioning s ys tems used to cool office buildings, shopping malls, and other large indoor spaces. E nd uses include CFC - 11 (low pressure) chillers, CFC - 12 centrifugal chillers, CFC - 12 reciprocating chillers, HCFC - 22 chillers, CFC - 114 centrifugal chillers, and CFC - 500 centrifugal chillers;

 In dustrial Process Refrigeration : R efrigeration sy stems used in the chemical, pharmaceutical, petrochemical, and other manufacturing and food processing industries. T hese include both packaged and built - up sy stems used in manufacturing processes as well as extra - large ice makers;

 Ice Skating Rinks : T here are several different ty pes of ice rink sy stems, but all are grouped into one end use in this analy sis;

 Ice Makers : T hese include small, medium, and large ice makers used by a number of entities, in cluding restaurants and hotels;

 Household and Li ght Commercial Air Conditioning : T hese include window units, packaged terminal air conditioners, central air conditioners, direct expansion commercial air conditioners, and heat pumps used for space cooli ng and heating in homes and businesses. A ll sy stems in this end use currently use HCFC - 22;

 Refrigerated Appliances : T hese include household refrigerators and freezers, water coolers, vending machines, and dehumidifiers. M ost currentl y use CFC - 12 as a refrigerant, but there are some CFC - 502 units in existence;

 Refrigerated Transport Systems : T hese include sy stems designed to refrigerate materials in transit. T hey are found in trucks, trains, and ships; and

 Mobile Air Conditioning : T his end use includes sy stems installed in motor vehicles for the comfort of occupants. The following substitutes to Class Iand Class II substances are examined in this report:

$ **HCFCs** : H CFCs are chemically similar to CFCs except that they contain hydrogen in add ition to chlorine and fluorine. H CFCs anal yz ed as possible substitutes to the use of Class Ichemicals in the refrigeration sector include HCFC - 22, HCFC - 123, HCFC - 124, HCFC - 141b, and HCFC - 142b.

$ **HFCs** : H FCs do not contain chlorine and do not contribute to destruction of stratospheric ozone. T hey can, however, have high greenhouse gas potentials and may c ontribute to global warming. H FCs analyzed as possible substitutes to Class I and Class II substances in the refrigeration sector include HFC - 134a, HFC - 152a, HFC - 143a, HFC - 125, HFC - 227ea, and HFC - 23.

$ **Hydrocarbons** : P ropane, ethane, prop yl ene, and (to some extent) butane are used as refrigerants in specialized industrial applications, primarily in o il refineries and chemical plants. P erfluoropropane and other perfluorocarbons (PFCs) also have potential applications in the refrigeration sector.viii

$ **Ammonia** : Ammonia has been used as a refrigerant in vapor compression cycles for more than 100 ye ars. Its main application is in moderate to low temperatures sy stems.

$ **Chlorine** : C hlorine has been proposed as a Class I s ubstitute refrigerant for use in chlorine liquification, a processing step in the manufacture of the chemical.

$ **Potential Substitutes S ubmitted as Confidential Business Information**  . Af ew substitutes included in this analy sis were submitted by their manufacturers as confidential business information. A s a result the identity of these substances are not revealed. T he results of the use analy ses for these compounds are presented under the following identities: R200b through 200i; and HCFC/HFC/Fluoroalkane. In addition to these chemical substitutes, there are a number of alternative technologies considered in thi s risk screening anal ys is:

$ **Absorption Refrigeration Systems** : Absorption refrigeration s ys tems are a major existing alternative to sy stems based on vapor compression cycles. Ammonia and lithium bromide are used in absorption refrigeration and air conditioning sy stems. $ **Evaporative Cooling** : E vaporative cooling is another technology that could be an alternative to CFC - and HCFC - based vapor compression sy stems in some applications. C ontrary

to vapor compression sy stems, evaporative coolers do not require compressors and consequentl y can offer considerable energy savings. **ES.2 R** **ISK SCREENING METHODOLOGY** To examine risks associated with the use of substitutes for ODSs in each sector, EPA examined many

different ty

pes of exposure routes, receptors, and effects. A s discussed in more detail later, EPA used an atmospherics modeling framework to assess global ozone depletion and associated health effects. T o examine risks to workers, consumers, and the general population, EPA first conducted screening - level assessments using generall y conservative assumptions to identify scenarios potentially

of concern, and then conducted more in - depth assessments of those scenarios. T hese risk screening assessments were conducted in three basic steps: (1) Assess exposure . E PA estimated levels of substitutes to which workers, consumers, the general population, and environmental receptors may be exposed, and over what period of time. (2) Evaluate toxicity . E PA compiled information on the toxicity of each substitute, including occupational exposure limits, reference concentrations, and cancer slope factors. T hese values were identified from an appropriate source (e.g., Permissible Exposure L imits [PEL s] from the Occupational Safet y and Health Administratio n [OSHA]) or were derived for this report using extrapolation and other techniques. (3) Estimate risk . E xposure assessment results were combined with toxicity v alues to estimate risks. Uncertainties in the risk estimates were anal yz ed qualitatively .ix

EP A did not estimate risks for every possible combination of substitute, end use, and t ype of effect; combinations that clearl y were not of concern were not anal yz ed. F or example, substitutes that volatilize quickly when exposed to the atmosphere were not e xamined for potential releases to streams and effects on aquatic life. E PA believes that all of the significant human health and environmental exposure pathway s and effects were covered in the risk screen. Below are brief descriptions of how the general approach discussed above was applied to the risk screen for the refrigeration sector. **Worker Exposure and Risk** . E PA used a mass - balance model to estimate worker exposure to HCFC and HFC refrigerant and air conditioning substitutes for ODSs used in this s ector. P otential exposure levels to the substitutes were assessed during the manufacture, installation, and servicing of refrigeration and air conditioning equipment. E stimated exposures were compared to OSHA and EPA occupational exposure limits to scree n the potential risks to workers. **Consumer Exposure** . C onsumers may be exposed to ODS substitutes that could potentially

be used in household refrigeration and air conditioning equipment and mobile air conditioners. M ass - balance models were us ed to estimate the risks from short term and long term exposures to ODS substitutes used in these end uses. T o assess noncarcinogenic effects, estimated long term exposures were compared to reference concentrations. C ancer risks were calculated using standard risk equations. T he estimated short term exposures were compared to interim emergency

guidance levels (EGLs) developed by EPA for each substitute. **General Population Exposure** . T o screen risks to the general population, EPA considered releases fro m the following t ypes of facilities: m anufacturing facilities that produce refrigeration or air conditioning equipment, operating facilities using refrigeration or air conditioning equipment, service stations (mobile air conditioners only), and recycling centers (household refrigeration and air conditioning end uses only) or salvage yards (mobile air conditioners only). M odel facilities were developed for each refrigeration and air conditioning end use. F or each t ype of facility, conservative release est imates were multiplied by dispersion factors to predict fenceline concentrations of HCFC, HFC, and other chemical substitutes downwind of these facilities. T hese concentrations were then compared to estimated reference concentrations to screen noncancer h ealth risks. C ancer risks were calculated using EPA's standard risk equation. **Atmospherics** . In this analy sis, two different baselines are employed to present the atmospheric impacts associated with each of the potential substitutes in a given end use: an "ideal" or "no - risk" baseline, and a "no - substitution" baseline. T hese two baselines bound the range of health effects, since the first examines impacts from a risk - free scenario and the second presents effects assuming continued use of all CFCs. T hes e baselines can be summarized as follows:

$ "Ideal" Baseline : T his baseline presents the incremental ODP risks associated with the use each of the potential substitutes in a given end use relative to a hy pothetical substitute with an ODP of 0.0. In esse nce, this baseline presents the increase in ODP risks that could result from the use of the substitutes relative to a no risk (or ideal) baseline.x

$ No Substitution Baseline : Under this baseline, the incremental performance of each substitute within an e nd - use is judged against continued use of Class I and Class II substances. In essence, this baseline presents the reduction in ODP risks associated with phasing out the use of the Class I compound in a given end use and switching to each of the potential substitutes. EPA used the Atmospheric and Health Effects Framework (AHEF) to model the effects of substitutes for ODSs in the refrigeration and air conditioning sector. T he framework employs the Vintaging Model for forecasting consumption and emissions o f refrigeration and air conditioning substitutes. T he Atmospheric Stabilization Framework (ASF) uses these emissions as a basis for predicting changes in ozone levels. C hanges in UV - B flux are then estimated from the ASF output. F inally , AHEF utilizes a human health effects model to calculate skin cancer cases and fatalities. **VOCs** . V OC emissions from the refrigeration and air conditioning end uses were estimated under the conservative assumption that all ODSs currentl y used in refrigeration and air con ditioning equipment would be replaced with VOCs. T hese emissions were then compared to total VOC emissions from all sources at the national level. The use of substitutes for ODSs in the refrigeration and air conditioning sector were assumed to result in no releases of chemicals to surface waters that could result in potential risks to the general population or aquatic life, nor were the substitutes expected to result in the generation of solid waste that could potentially result in risks to the general po pulation. **ES.3 RISK SCREENING RESULTS**  The results of EPA's risk screens are summarized briefl y below and discussed in greater detail in the body

of this report. **Atmospherics** . E xhibits ES - 1 and ES - 2 summarize the impacts on skin cancers, fatal ities, and cumulative Clx resulting from the use of the potential ODS substitutes in the refrigeration and air conditioning sectors relative to the ideal and no substitution baselines, respectivel y. E xhibit ES - 1 (ideal baseline) indicates that for the vas t majority of end use and substitute combinations the increase in skin cancers is less than 10,000 cases and the increase in fatalities is less than 1,000, relative to the ideal baseline. T he greatest increase in skin cancers and fatalities results from c ertain substitutes examined in the MACs sector. T his is due to (1) the significant quantities of chemical use in the MACs sector; (2) the ODPs of some of the alternatives examined; and importantly (3) the timing of the availability of the chemical substitutes. Exhibit ES - 2 (no substitution baseline) indicates that virtually all of the substitutes anal yz ed are substantially

less harmful to the ozone layer than continued use of CFCs. **Worker exposure** . T he results of EPA's anal ys is indicates that for the va st majority of end use, substitute, and operation combinations workers will not be exposed to potentially hazardous airborne gas or vapor concentrations. E xhibit ES - 3 summarizes the results for those scenarios where the model suggests that worker exposure s exceed either the 8 - hour or 30 - minute occupational exposure limit (OEL) for the alternative refrigerant (Exhibit ES - 4 summarizes the OEL s for the potential alternative refrigerants). In considering the implications of the results presented in Exhibit ES - 3, it is important to note the following observations that suggest that the anal yt ical results will overstate likel y occupational exposures to alternative refrigerants:xi

$ The emission estimates from the Vintaging Model used in the anal ys is are considered to be worst - case estimates.

$ The anal ys is does not assume the use of an y local exhaust ventilation, which is likely to be used in manufacturing and disposal operations involving any significant releases. T he use of properly designed local exhaust venti lation would likely prevent gas or vapor concentrations from exceeding the OEL s most of the time.

$ The anal ys is assumes for each release scenario that the entire dail y release occurs over a single 8 - hour workday at a single location. T his is not the cas e for many scenarios, and particularly for manufacturing operations, where the estimated dail y release may

occur over two or three workshifts or where the release may be spread over two or three production lines.

$ The vast majority of the exceedances ove r the OELs are the result of assuming that there will be no recycling of HFC refrigerants. G iven that such recycling isxii

es2xxi **EXHIBIT ES -**  **3 SUMMARY OF ESTIMATED WORKER EXPOSURE TO ALTERNATIVE REFRIGERANTS**  **FOR SCENARIOS WHERE THE OCCUPA TIONAL EXPOSURE LIMIT IS EXCEEDED**  a 8 - Hour TWAb 30 - Minute TWA End - Use Sector Operation Substitute Material c Predicted

Exposure (ppm) Operation Substitute Material c Predicted

Exposure (ppm) Retail Food (Parallel Sy stem) Disposal HFC - 134a HFC - 125 HFC - 143a HFC - 23 1,579 1,342 1,917 2,300 Disposal HFC - 134a HFC - 125 HFC - 143a HFC - 23 4,742 4,030 5,757 6,909 Cold Storage Warehouses Disposal HFC - 152a HFC - 23 1,309 1,234 Centrifugal Chillers (Low Pressure) Manufacture HCFC - 123 73 d Centrifugal Chillers (High Pressure) Disposal HFC - 124 HFC - 134a HFC - 227ea 2,271 3,050 1,647 Disposal HFC - 124 HFC - 134a HFC - 227ea 6,819 9,159 4,928 Industrial Process (Low Pressure) Manufacture Repair HCFC - 123

HCFC - 123 54 49xxii **EXHIBIT ES -**  **3 (continued)**  **SUMMARY OF ESTIMATED WORKER EXPOSURE TO ALTERNATIVE REFRIGERANTS FOR SCENARIOS WHERE THE OCCUPATIONAL EXPOSURE LIMIT IS EXCEEDED**  a 8 - Hour TWAb 30 - Minute TWA End - Use Sector Operation Substitute Material c Predicted

Exposure (ppm) Operation Substitute Material c Predicted

Exposure (ppm) Industrial Process (High Pressure Build - Up) Manufacture Disposal HFC - 143a

HFC - 152a HFC - 134a HFC - 152a HFC - 125 HFC - 143a HFC - 23 1,293 1,016 30,840 47,661 15,740 18,375 13,490 Manufacture Disposal HFC - 134a

HFC - 143a HFC - 152a HFC - 134a HFC - 152a HFC - 125 HFC - 143a HFC - 23 3,941 7,751 6,090 92,608 143,122 47,266 56,260 40,509 Large Ice Makers Repair HFC - 152a 1,076 Ice Rinks Disposal HFC - 134a HFC - 152a HFC - 23 4,609 7,123 2,016 Disposal HFC - 134a HFC - 152a HFC - 23 13,840 21,390 6,054 Central A/C and Home Heat Pumps Manufacture HFC - 152a 1,332

a Exposure levels are rounded to the nearest whole number. b Time - weighted average. c One manufacturer's representative states that worker exposures to HCFC - 123 during centrifugal chiller manufacture are ty pically 1 p pm or less, due to the use of exhaust ventilation. d The refrigerant blends analyzed for these sectors may b e considered confidential business information (CBI) by the manufactur er. A s a result, the identification of the constituents of any blend and the proportion of each constituent contained in any blend are not present ed in this exhibit.xxiii **EXHIBIT ES -**  **4 OCCUPATIONAL EXPOSURE LIMITS FOR**  **POTENTIAL ALTERNATIVE REFRIGERANTS*** Substitute Material WGL(ppm) EGL(ppm) HCFC - 22 1,000 5,000 HFC - 23 1,000 3,000 HCFC - 123 30 2,500 HCFC - 124 1,000 3,000 HFC - 125 1,000 3,000 HFC - 134a 1,000 3,000 HFC - 143a 1,000 3,000 HCFC - 142b 1,000 5,000 HFC - 152a 1,000 4,000 HFC - 227ea 1,000 3,000

required under the Clean Air Act beginning in 1995, exposures should be below the OEL s for these compounds.

$ The model's tendency to overstate worker exposures is further supported by sampling obtained for HCFC - 123 refrigerants during repair operations conducted on low - pressure centrifugal chillers. Finally , the anal ys is did not consider the use of ammonia, butane, propane, or perfluoropropane as alternative refrigerants. H owever, existing OSHA and ASHRAE standards governing the handling and use of these materials should serve to limit occupational exposures to them. **Consumer exposure** . E PA's consumer exposure anal ys is of household refrigeration, household air conditioning, and mobile air conditioning equipment indicates that unless the enti re refrigerant charge is released over a short period of time, none of the substitutes exceed EPA's threshold of concern for human health risk in any piece of equipment. R outine leakage and servicing with recycling simply will not release enough refrigerant to pose significant short - term or long - term risks to human health. If the entire charge is released (due to an accident or during servicing without recycling of HFC - containing equipment), then the 30 - minute average concentrations exceed the EGLs for substitutes in household air conditioning equipment only . T he following factors should be considered when judging whether these exceedances are cause for concern:

$ Recycling at servicing will be required for the HFCs by 1995. Until then, EPA believes that most HFCs will be recycled any way , because of their high cost relative to CFCs.xxiv

$ Accidental releases of an entire refrigerant charge occur infrequentl y. T he UNEP (1992) reports that less than 5 percent of the refrigerators and freezers have accidental releases of the entire charge.

$ Exposures are below levels that would raise concern for cardiotoxic effects. T his would be true even if higher, shorter - term TWA exposures (e.g., 15 - minute TWAs) had been used as the basis for the assessment. **General population exposure to ambient air releases** . E PA's general population exposure anal ys is indicates that even with conservative screening assumptions there are no end uses within the refrigeration and air conditioning sectors where the use of HFCs o r HCFCs as substitutes for CFCs will result in exposure concentrations above the chemicals' health - based reference concentrations for non - cancer effects. S imilarly , there are no areas for which predicted cancer risks would be above the upper - bound cancer risk level of concern. T he anal ys is also indicates that general population exposures are not of concern for ammonia, butane, propane, and perfluoropropane. **VOCs** . E PA's analy sis indicates that potential VOC emissions from all substitutes for all end uses in the refrigeration and air conditioning sector are likel y to be insignificant relative to VOC emissions from all other sources.**1. I**  **NTRODUCTION**

This report documents the results of the examination of human health and environmental risks a ssociated with the use of substitutes for ozone depleting substances (ODSs) in the refrigeration and air conditioning sectors. 2 This introduction provides a brief background on the history and philosophy

of the Significant New Alternatives Policy (SNAP) p rogram, discusses in general terms the ty

pes of anal ys es performed to screen the risks from the substitutes, and provides a list of the chapters that follow. **1.1 BACKGROUND**  Over the past decade, a series of diplomatic and legislative efforts have taken p lace in response to growing concerns over the progressive depletion of the Earth's stratospheric ozone layer and its attendant health and environmental problems. T he first major step was in September 1987, when the United States and 23 other nations signe d the Montreal Protocol. T he original agreement established a schedule for reducing b y half the production and consumption of eight specific ODSs, including CFC - 11, CFC - 12, CFC - 113, CFC - 114, CFC - 115, Halon - 1211, Halon - 1301 and Halon 2402. When the partie s to the Protocol met again in Lo ndon in June 1990, they agreed to fully

phase out the original eight ODSs, as well as methyl chloroform, carbon tetrachloride, and other fully halogenated CFCs. Congress incorporated the requirements of the London Amendments into the Clean Air Act (CAA) Amendments of November 15, 1990, and in some cases went beyond the London requirements. T itle VI of the CAA differs from the L ondon Amendments by mandating a faster phaseout of meth ylchloroform, a restriction on the use of hydrochlorofluorocarbons (HCFCs) after 2015, and a ban on the production of HCFCs after 2030. When the Parties to the Montreal Protocol met in Copenhagen in November 1992, they further accelerated the phaseout dates for many controlled substances. T o implement the Copenhagen amendments and adjustments, EPA promulgated regulations in December 1993 that set the phaseout date at January 1, 1996 for Class I substances (as defined in the CAA), with the exception of halons which were subject to a phaseout b y J anuary

1, 1994. T he regulation also includes a phaseout of methyl bromide b y the ye ar 2001. Section 612 of the CAA requires EPA to develop a program to evaluate the risks to human health and the environment posed by alternatives to ODSs. E PA is referrin g to this new program as the Significant New Alternatives Policy (SNAP) program. T he SNAP program is directed at fulfilling the general mandate in Section 612 of identifying acceptable and unacceptable substitutes for the Class I ODSs. Initial SNAP imple mentation involves two key activities: (1) developing, promulgating, and administering a regulatory program for identifying and evaluating substitutes, and (2) publishing a list of acceptable and unacceptable substitutes for specific end uses.

2 Other sectors evaluated in separate reports are solvent cleaning, foam blowing, fire extinguishing, aerosols, sterilization, and adhes ives, coatings, and inks.EPA took the first major step in implementing Section 612 of the CAA on January 16, 1992, with publication of a Request for Data and Advance Notice of Proposed Rulemaking (ANPRM; 57 Federal Register , p. 1984). T his notice, developed with the help of the S tratospheric Ozone Protection Advisory Committee (STOPAC), presented the initial plan for implementing the SNAP program and requested producers and formulators of substitutes for ODSs to provide EPA with information to facilitate review of the substitutes. A Notice of Proposed Rulemaking was published in the Federal Register on May 1 2, 1993. T he proposed rule described the proposed structure and process for administering the SNAP program and presented initial determinations on the acceptability of key sub stitutes. T his Final Rule provides both the SNAP process and additional SNAP determinations on the acceptability of substitutes. In the future, substitutes will be addressed on a case - by - case basis through individual notices. In addition, EPA will accep t petitions requesting that a substance be added or deleted from either of the lists. **1.2 EVALUATION OF SUBSTITUTES**  To develop the lists of unacceptable and acceptable substitutes, EPA conducted a comprehensive screening assessment of the h ealth and environmental risks posed by various substitutes in the context in which they are used. S ubstitutes are grouped into one or more of eight general sectors: r efrigeration and air conditioning; solvent cleaning; foam blowing; fire extinguishing; a erosols; sterilization; adhesives, coatings, and inks; and tobacco expansion. Within each sector, substitutes are evaluated in the context of particular end uses. E xamples of end uses within the refrigeration and air conditioning sectors include cold sto rage warehouse refrigeration sy stems, household refrigerators, and mobile air conditioners. E PA also determined the feasibility

of using each substitute by assessing its production capacity and projected market share. B ased on these analy ses, EPA will id entify as "unacceptable" onl y those substitutes that pose significantly

higher human health and environmental risks than other available substitutes. EPA does not intend to restrict substitutes that are only marginall y worse based on some criteria. EPA's evaluation of each substitute in each end use is based on the following t ypes of information and anal ys es:

 **Atmospheric effects** are assessed by using models to predict stratospheric ozone depletion. O zone depletion is measured in terms of cumulative Cl x loadings and increased incidence of skin cancer cases and skin cancer mortalities. C hanges in global temperatures may

result from releases of the substitutes themselves or from changes in fossil fuel use due to increases or decreases in energy efficienc y. T hese impacts are discussed qualitatively .

 **Exposure** assessments are used to estimate levels of substitutes to which workers, consumers, the general population, and environmental receptors may be exposed, and over what period of time. T hese assessme nts are based on personal monitoring data or area sampling data if available. O therwise, exposures are assessed using measured or estimated releases as inputs to mathematical models. Exposure assessments may be conducted for many

ty pes of releases, inclu ding releases in the workplace and in peoples' homes; releases to ambient air and surface water; and releases from the management of solid wastes.

 **Toxicity** data are used to assess the possible health and environmental effects from exposure to the substi tutes. I f Occupational Safety and Health Administration (OSHA) - approved or EPA - wide health - based criteria such as Permissible Exposure L imits (PEL s; for occupational exposure), reference concentrations  3 (RfCs; for noncarcinogenic effects), or cancer slope factors (for carcinogenic risk) are available for a substitute, exposure information is combined with this toxicity information to determine whether there is potential for concern. O therwise, toxicity data are used in conjunction with existing EPA guideli nes to develop health - based criteria for interim use in these risk screens.

 **Flammability** is examined as a possible safet y concern for workers and consumers. E PA screens flammability risk using data on flash point and flammability

limits (e.g., OSHA flammability /combustibility

classifications), test data on flammability

in consumer applications conducted by independent laboratories (e.g., Underwriters Laboratories), and information on flammability risk minimization techniques.

 Some of the proposed sub stitutes are **volatile organic compounds (VOCs)** , which are chemicals that increase tropospheric air pollution by contributing to ground - level ozone formation. L ocal and nationwide increases in VOC loadings from the use of substitutes are also evaluated. In conducting these assessments, EPA made full use of previous anal ys es, including the 1990 interim assessments prepared b y EPA's Office of Pesticides and Toxic Substances (OPTS) and the supporting documentation (full citations are given in appropriate chapters of this report). These analy ses were modified in some cases to incorporate more recent data or new field experience. Where possible, EPA incorporated data submitted in response to the ANPRM and NPRM. F inally , these analy ses assume that the regulated community is in compliance with applicable requirements of other statutes and regulations administered by EPA (e.g., recycling requirements promulgated under the CAA) and other federal agencies (e.g., enforceable workplace standards set b y OSHA). **1.3 RISK SCREENING REPORTS FOR REFRIGERATION AND AIR**  **CONDITIONING** The remainder of this package includes a series of chapters on the following topics:

 Overview of substitutes and end uses;

 Human health and environmental concern levels for substitutes;

 Atmospherics modeling (ozone depletion, global warming);

 Occupational exposure and risk screening anal ys is;

 Consumer exposure and risk screening anal ys is;

 General population exposure and risk screening analy sis (ambient air); and

 VOC anal ys is. Flammability

is addressed within several of the chapters. C ompliance costs are addressed in conjunction with other SNAP decisions in a separate package, as are regulatory burdens and effects on small businesses.  4

Finally , three of the substitutes analyzed in this report, HCFC - 123, HCFC - 124, and HFC - 134a contribute to or generate trifluoroacetic acid (TFA) as an atmospheric transformation product. T he potential ecological effects on aqueous and terrestrial ecos ys tems are not addressed in this report because of insufficient data on the toxicity o f TFA and the level to which ecos ys tems may be exposed. R esearch efforts of the Agency in cooperation with the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS) are unde rway to define the potential ecological risks associated with the formation of TFA in the environment. Although there are significant uncertainties about the potential risks associated with TFA, and research is continuing to address these risks, a number of preliminary statements can be made based on the research completed to date 3 :

 Research indicates that virtually 100% of the HCFC - 123 and HCFC - 124 released to the environment will degrade to TFA, and suggests that approximately 25% to 40% of HFC - 134a w ill also degrade to TFA.

3 See Alternative Fluorocarbons Environmental Acceptability Study (AFEAS). 1 991. " Kinetics and Mechanisms for the Reactions of Halogenated Organic Compounds in the Troposphere." STEP - HALOCSIDE/AFEAS WORKSHOP, Dublin. M ay 14 - 16, 1991. S ee also AFEAS. 1993. "Production, Sales, and Atmospheric Releases of Fluorocarbons Through 1992."  5

 TFA is a highl y soluble acid that will exist primarily in aqueous environments (rain, rivers, lakes, ocean, and groundwater). T ests have shown that it is very resistant to decomposition and will therefore reside in the environment for long periods of time.

 Given conservative estimates of global HCFC and HFC use and emissions, the environmental concentrations of TFA will be low over the next few decades.

 Experimental results show at high concentrations TFA has lo w to moderate acute toxicity to animals and initial tests indicate that relatively high concentrations of TFA cause toxic effects on some plants and algae. R esearch to evaluate these effects is continuing.

 The expected environmental concentrations of T FA over the next few decades are unlikely to pose a significant hazard to animals or plants.

 There has been concern that TFA might degrade to MFA (monofluoroacetic acid) and that MFA could exist at high enough concentrations to pose health and environme ntal risks. R esearch to date has identified no environmental process that would convert TFA to MFA. R esearch to elucidate all the degradation pathway s for TFA, including potential pathway s to MFA is continuing. EPA is closely

monitoring the research eff orts underway

with respect to TFA, and will assess the long term ecological risks associated with this compound when the research is completed. A s noted above, research completed to date has not uncovered any risks that warrant the implementation of measures to control atmospheric concentrations of TFA. I f such risks are identified in the future, the Agency will re - assess its position on TFA and evaluate measures to mitigate such risks.**2. O**  **VERVIEW OF SUBSTITUTES AND END USES**

**2.1 END USES**  The refrigeration industry was the first to make widespread use of CFCs after this class of chemical compounds was discovered in the 1930's. In 1990, refrigeration and air conditioning accounted for almost 22 percent of the total use of Class I substances in the United States. T here are over 500 million pieces of refrigeration and air conditioning equipment that use these chemicals as the working fluids in a vapor compression cycle. Many Class I substances exhibit desirable thermophy sical properties for use in refrigeration cycles. T hey are relativel y nontoxic, nonflammable, and inexpensive to produce B characteristics that have contributed to their appeal as refrigerants. C FC - 12 is the most widely used refrigerant, with applications in mobile air condi tioners (MACs), household refrigerators and freezers, various appliances, chillers, retail food refrigeration equipment, cold storage warehouses, refrigerated transport s ys tems, and industrial equipment. C FC - 11 is most commonly used to provide cooling for large buildings, while CFC - 115, as a component in the refrigerant blend R - 502, is used for low temperature applications in a variety of sectors. C FC - 113 and CFC - 114 are used in special applications chillers. Of the Class II controlled substances, HCFC - 2 2 is the most common refrigerant in small to medium size air conditioning s ys tems, and some ty pes of retail food and industrial process refrigeration s ys tems. EPA has divided the refrigeration and air conditioning sector into the following general end use s:

 Retail Food Systems : T hese include stand alone refrigeration cases found in small markets, convenience stores, restaurants and other food establishments, large parallel s ys tems found in supermarkets, and HCFC - 22 sy stems found in a wide variet y of re tail and service establishments;

 Cold Storage S ys tems : P ublic and private facilities used to store meat, produce, dairy products, frozen foods, and other perishable goods. T hese s ys tems refrigerate warehouses of varying sizes and include high pressure and low pressure sy stems;

 Chillers : T hese are large commercial air conditioning s ys tems used to cool office buildings, shopping malls, and other large indoor spaces. E nd uses modeled are CFC - 11 (low pressure) chillers, CFC - 12 centrifugal chillers, CF C - 12 reciprocating chillers, CFC - 114 centrifugal chillers, and CFC - 500 centrifugal chillers;

 Industrial Process Refrigeration : R efrigeration sy stems used in the chemical, pharmaceutical, petrochemical, and other manufacturing and food processing industries. T hese include both packaged and built - up sy stems used in manufacturing processes as well as extra - large ice makers; Ice Skating Rinks : T here are several different ty pes of ice rink sy stems, but all are grouped into one end use in this analy sis;

 Ice Makers : T hese include small, medium, and large ice makers used by a number of entities, including restaurants and hotels;

 Household and Li ght Commercial Air Conditioning : T hese include window units, packaged terminal air conditioners, central air conditioners, direct expansion commercial air conditioners, and heat pumps used for space cooling and heating in homes and businesses. A ll sy stems in this end use currently use HCFC - 22;

 Refrigerated Appliances : T hese include household refrig erators and freezers, water coolers, vending machines, and dehumidifiers. M ost currentl y use CFC - 12 as a refrigerant, but there are some CFC - 502 units in existence;

 Refrigerated Transport Systems : T hese include sy stems designed to refrigerate materi als in transit. T hey are found in trucks, trains, and ships; and

 Mobile Air Conditioning : T his end use includes sy stems installed in motor vehicles for the comfort of occupants. Industry has invested heavily

in the search for suitable alternative refrigerants that exhibit the favorable characteristics of the controlled substances, but that do not contribute to stratospheric ozone depletion or global warming. T he h ydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) have received the most attention, along with expanded use of traditional refrigerants such as ammonia and h ydrocarbons. In man y cases the most promising solution appears to be a blend of refrigerants. D espite great progress, the suitability of many replacements is still uncert ain. T oxicity concerns, high ozone depletion potentials, or flammability

may limit the ultimate attractiveness of potential substitutes in many applications when testing is completed. T he 1991 report by UNEP's Refrigeration, Air Conditioning, and Heat Pumps Technical Options Committee contains detailed information about the status of alternative refrigerants in various applications. EPA believes that HCFCs have an important role to play a s transitional refrigerants, both in retrofit applications and in n ew equipment. H CFCs have the disadvantage that they d o contribute to the destruction of stratospheric ozone, although to a much lesser extent than CFCs. H FCs have ozone depletion potentials (ODPs) of zero, but their practical application is years away in man y cases. T he interim use of HCFCs, until such time as safer alternatives are available, will allow industry t o move away

f rom CFC refrigerants more rapidl y. E PA believes that this approach will have greater environmental benefits than permitting the continued use of CFCs until equipment that uses HFCs becomes available. **2.2 ALTERNATIVE REFRIGERANTS**  **2.2.1 HCFCs**  HCFCs are chemicall y similar to CFCs except that they contain hydrogen in addition to chlorine and fluorine. H CFC - 22 has been used as a ref rigerant for man y ye ars. It is the primary refrigerant used in small to medium sized air conditioners and chillers, and has found increasing application in medium temperature retail food refrigeration sy stems. H CFC - 123 holds promise as the primary

retrof it option for CFC - 11 in low pressure centrifugal chillers. H CFC - 124 has  8

potential applications in blends for man y t ypes of refrigeration equipment and, as a pure refrigerant, has been suggested as a replacement for CFC - 114 in high pressure centrifugal chi llers. Because they

c ontain hydrogen, the HCFCs break down more easily i n the atmosphere, and therefore have lower ODPs. T heir global warming potentials are lower than either the CFCs or the HFCs. P roduction of HCFCs is controlled by the Clean Air Act Amendments of 1990. Beginning in 2015, it will be unlawful to produce HCFCs for uses other than in equipment manufactured before 2020. B eginning in 2030, it will be unlawful to produce HCFCs, except for certain purposes that are exempted. Because their thermophysical properties are, in many cases, similar to CFCs, equipment designed to use CFCs can sometimes be retrofitted to operate with HCFCs. A s noted above, EPA believes that HCFCs will play an important role as transitional refrigerants. T here are c lear environmental benefits to be gained b y allowing their use until better substitutes are developed. **2.2.2 HFCs**  HFCs do not contain chlorine and do not contribute to destruction of stratospheric ozone. Many , however, have relatively high greenhouse gas potentials and contribute to global warming. Although a few HFCs have been in use for some time (HFC - 152a is a component in the azeotropic blend R - 500, used in smaller tonnage reciprocating equipment and large tonnage centri fugal equipment), the potential for HFCs as a replacement for CFCs has only r ecently b een investigated. HFC - 134a and HFC - 152a hold the most promise as single - substance replacements for Class I and Class II refrigerants. H FC - 143a and HFC - 125, as parts of blends, have been considered as substitutes for R - 502 in low temperature refrigeration applications. H FC - 227ea has possible applications as a refrigerant in mixtures used in high pressure centrifugal chillers. H FC - 23 and HFC - 32, when used in blends with other chemicals, have been proposed as a potential substitute for certain HCFC - 22, CFC - 13, and R - 503 end - uses. **2.2.3 Hydrocarbons**  Propane, ethane, prop yl ene, and, to some extent, butane are used as refrigerants in specialized industrial applications, pri marily oil refineries and chemical plants, where they are frequentl y available as part of the process stream and where their use contributes only slightl y to the incremental risk of fire or explosion. T hese industrial systems are specially designed to mee t rigid requirements for reliability , durability , and safet y. A SHRAE Standard 15, Safety Code for Mechanical Refrigeration , and Standard 34, Refrigerants , are incorporated into building codes in most of the U.S. T hese standards limit the use of flammable refrigerants in many applications. Perfluoropropane and other perfluorocarbons (PFCs) have potential applications in the refrigeration sector as well. **2.2.4 Ammonia**  Ammonia has been used as a refrigerant in vapor compression cycles for more than 100 ye ars. It is by

far the refrigerant of choice in many food processing and industrial applications, such as the meat packing, chicken processing, dairy , frozen juice, brewery , and cold storage industries. It is also widely used to refrigerate holds in fishi ng vessels. Industrial process refrigeration equipment uses rotary screw or reciprocating compressors. A mmonia's main application is when moderate to low temperatures are required. Ammonia has a characteristic pungent odor, excellent refrigerant properties, is low in cost, and has no long - term environmental drawbacks. It is moderately flammable and toxic, however, but it is not a cumulative poison.  9

Occupational Safety and Health Administration (OSHA) standards specify that the maximum allowable concentration of ammonia for an eight - hour working exposure is 50 ppm. **2.2.5 Chlorine**  Chlorine has been proposed as a Class I substitute refrigerant for use in chlorine liquification, a processing step in the manufacture of the chemical. When chilled below its boiling point, chlorine can be stored as a liquid at atmospheric pressure, a method that for safety reasons is much preferred to storing the chemical as a pressured gas at ambient temperatures. Compatibility

o f the refrigerant with liquid chlorine is cri tical because of chlorine's high reactivity ; CFC - 12 has been widel y used because it is nonreactive with chlorine. Chlorine compressors would be specialized units made to resist chemical attack by liquid and gaseous chlorine. B ecause a chlorine refrigerat ion sy stem would use part of the process stream as the refrigerant, the proposed use of chlorine as a refrigerant is analogous to that of hydrocarbon refrigerants in the oil and gas industry. E PA has determined that, if the refrigeration sy stem is placed so that any leakage or losses of chlorine would be contained and neutralized by the process safet y mechanisms, chlorine can be used safel y in these specialized applications. **2.2.6 Potential Substitutes that Manufacturers have Submitted as Confidential Bus**  **iness Information**  A few substitutes that may be used in certain refrigeration and air conditioning end uses have been submitted by

their manufacturers as confidential business information. A s a result, the identity of these substitutes are not r evealed in this anal ys is. T he results of the risk anal ys es for these compounds are presented under the following identities: R200b through R200i and HCFC/HFC/Fluoroalkane Blend A. **2.3 ALTERNATIVE TECHNOLOGIES**  **2.3.1 Absorption Refrigeration Systems**  Absorption refrigeration sy stems are the onl y major existing alternative to sy stems based on vapor compression cycles. Ammonia is also used in absorption refrigeration and air conditioning sy stems. S mall ammonia refrigeration units are popular in recreat ional vehicles and in some household applications as they n eed no electricall y driven mechanical compressor, rel yi ng instead on a propane flame as an energy source. S mall refrigerators using absorption technology are produced for use in hotel rooms, where the focus is on their silent operation rather than the lack of a suitable supply

of electricit y. S mall absorption ty pe s ys tems use h ydrogen to maintain a sy stem pressure high enough to allow the ammonia refrigerant to evaporate at low pressure and temper ature (and condense at room temperature), and are constructed to withstand high internal operating pressures. T he absorption mechanism itself is a sealed unit, which usually needs no servicing over its operating life. Commercial ammonia absorption sy stem s are used for air conditioning comfort cooling, particularl y in instances where waste heat is available. A s with all chillers, these produce chilled water, which is circulated to the space being cooled. L ithium bromide is also used in commercial absorpt ion sy stems, where it serves as an absorbent. S uch sy stems operate at very l ow pressure to allow water to act as a refrigerant. L ithium bromide is a relativel y nontoxic, nonflammable,  10

nonexplosive, chemically stable compound. B oth ty pes of absorption ch iller s ys tems have traditionally

been competitors to electricall y driven CFC chillers. **2.3.2 E**  **vaporative Cooling** Evaporative cooling is another technology that could be an alternative to CFC - and HCFC - based vapor compression systems in some applic ations. T hree ty pes of EC systems exist: direct, indirect, and desiccant - assisted. In direct EC, the airstream temperature is decreased by bringing the air into direct contact with liquid water. B ecause it humidifies when it cools, direct evaporative co oling can give customer comfort only where the ambient air is hot and dry , such as in the southwestern parts of the United States. Indirect sy stems use a heat exchanger between the water and the airstream, and desiccant - assisted s ystems use a desiccant to dry the air before it is exposed to water. T hese new developments have greatl y expanded the applicability of EC to include the entire U.S. Contrary to vapor compression sy stems, evaporative coolers do not require compressors and consequentl y c an offer c onsiderable energy savings. E vaporative coolers have been used for many years to provide cooling for comfort and for a variet y of industrial and agricultural applications. T hey

are energy - efficient, inexpensive to purchase, and have low operating costs.**3. T**  **OXICITY REFERENCE VALUES FOR SUBSTITUTES**

To assess potential health risks from exposure to substitutes for ozone - depleting substances (ODSs) in the refrigerants sector, EPA identified or developed toxicity r eference values for each subs titute. T hese values include occupational exposure limits, reference concentrations, and cancer slope factors. T he toxicity reference values were compared to or combined with predicted exposure concentrations to estimate risks to workers, consumers, and the general population, as described in subsequent chapters of this report. This chapter first discusses EPA's general approach for identifying or developing the toxicity reference values for substitutes examined in the SNAP background documents. S ection 3.1 discusses occupational exposure limits, and Section 3.2 discusses general population toxicity reference values. B oth of these sections pertain to the inhalation route of exposure. This chapter concludes by presenting the most recent toxicity referen ce values available for the substitutes covered in the refrigerants sector at the time of publication of this background document (Exhibit 3 - 1). T he list of substitutes presented in Exhibit 3 - 1 is not all inclusive; however, the Agency believes that the s ubstitutes selected for this review are representative of the ty pes of agents that could replace ODSs in this sector. T he Agency has also included in this screen replacement chemicals that may have high toxicity

potential to ensure that the assumptions us ed in the subsequent hazard assessments are valid and conservative. **3.1 OCCUPATIONAL**  **4 (INHALATION) EXPOSURE LIMITS**  Allowable occupational exposure limits (OEL s) for continuous and short - term exposure, denoted as the workplace guidance level (WGL) and emergency guidance level (EGL), respectivel y, are used to examine potential risks to workers. Whenever available, the W GL s and EGL s are based on OEL s developed by the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), or the American Industrial Hygiene Association (AIHA). The Occupational Safety and Health Administration (OSHA) is a governmental agency within the Department of L abor that sets enforceable occupational standards. L imits set by OSHA include permissible exposure limits (PEL s 5 ) and short - term exposure limits (STEL s). T he PELis an 8 - hour time - weighted average (TWA) airborne exposure limit that is designed, to the extent feasible, to reduce a significant risk of material impairment of health or functional capacity associ ated with exposure to a hazardous substance. T he STELi s the employee's 15 - minute TWA exposure that should not be exceeded at any time during a work day. It is designed to protect workers from experiencing adverse acute health effects such as respiratory irritation, eye irritation,

4 In some cases, these occupational exposure limits were also used to assess general population/consumer risk. 5 On July 7, 1992, th e 11 th Circuit Court of Appeals overturned permissible exposure limits (PELs) for 428 chemicals that were set by OSHA in January 1989. Employers are now legally bound to observe the 1971 PELs codified in 29 CFR 1910.1000. E PA has, howev er, decided to continue using the January 1989 proposed PELs for the purposes of the SNAP risk screen because these values are more representative of ACGIH TWA threshold limit values (TLV - TWAs) and AIHA workplace environmental exposure levels (WEELs), and cover a wider rang e of chemicals.and narcosis. It must be noted that because OSHA's exposure limits are legall y enforceable,

OSHA must consider a variety of factors including technologic and economic feasibility in establishing them. T hus, the limits set by OSHA do not solely reflect the toxicological properties of the material.  13

Exhibit 3 - 1  14

Exhibit 3 - 1 (cont.)  15

The National Institute for Occupational Safety and Health (NIOSH) , a governmental institute under the jurisdiction of the Department of Health and Human Services, develops recommended exposure limits (REL s) that are non - enforceable. Unlike OSHA, NIOSH is not constrained b y issues of technical or economic feasibility or significance of risk when deriving REL s . N IOSH also estimates concentrations of chemicals that are immediately dangerous to life and health (IDLH), which represents "the maximum concentration from which. . . one could escape within 30 minutes . . . without experiencing any escape - impairing (e. g., severe eye irritation) or irreversible health effects" (NIOSH 1990). The American Conference of Governmental Industrial Hygienists (ACGIH) is a non - governmental limit setting body. A CGIH's non - enforceable TWA threshold limit values (TLV - TWAs) are sim ilar to OSHA's PELs. A CGIH does not formall y analy ze for technical feasibility , but there appears to be some implicit recognition of feasibility s ince TLVs are set to be protective for most workers but not so low as to be "undul y restrictive." A CGIH TLVs provided much of the basis for OSHA's 1989 air contaminant standards. The American Industrial Hygiene Association (AIHA) is also non - governmental. T he AI HA workplace environmental exposure levels (WEEL s) are like the TLVs in that the justification of a particular WEEL is based predominantly o n toxicological information rather than feasibility . H owever, it is likely that feasibility

is considered implicitly

since the WEELs are limits that are protective and practical. The long - term occupational exposur e limits (WGLs) used for the SNAP risk screening assessments are based on OSHA PEL s, NIOSH REL s, ACGIH TLV - TWAs, or AIHA WEEL s, if available. T he short - term occupational exposure limits (EGL s) are based on OSHA STEL s or NI OSH IDLHs, if available. E PA rec ognizes that in an industrial setting OSHA STEL s are ty picall y much lower than IDLHs and other emergency guidance levels, and that exposure at the OSHA STELis not a situation requiring emergency corrective action. T herefore, using OSHA STEL s as EGL s is a conservative way to screen risks from short - term exposure to chemicals. If OSHA, ACGIH, N IOS H, or AIHA OELs were not available for a substitute, and WGLs or EGLs were considered important for the risk screening assessment, they were estimated by EPA. A l though the estimated WGL s are intended to be analogous to OSHA PEL s, they are different in that PELs are developed b y a regulatory process and incorporate complex decision criteria such as technological feasibility . In estimating WGLs, EPA took into consi deration the characteristics of workers who are healthier and younger than the general population, and experience intermittent rather than continuous exposure. Where appropriate, WGL s were estimated to be ten times greater than the suggested reference con centration (see Section 3.2.1). If the resulting estimate was greater than the 1,000 ppm TLV - TWA set by ACGIH (1986) ". . . as a guide for good h ygiene practice for vapors of low toxicity" (i.e., the "good housekeeping" limit), then the latter was used fo r the risk screening analysis. The EGL estimate is similar to the NIOSH IDLH (i.e., the maximum concentration from which one could escape within 30 minutes without experiencing escape - impairing or irreversible health effects). It also resembles the emerg ency exposure guidance level (EEGL) and the short - term public emergency guidance level (SPEGL) suggested by NRC (1986) and the emergency

response planning guideline suggested by AI HA (1989). In instances when a substitute has an OELbut the available toxi cological data were not sufficient to develop a STEL , the ACGIH excursion limit recommendation as stated below was used to estimate the EGL:  16

"Excursions in worker exposure levels may exceed 3 times the TLV - TWA for no more than a total of 30 minutes during a work - day , and under no circumstances should they exceed 5 times the TLV - TWA, provided that the TLV - TWA is not exceeded" (ACGIH, 1992). Thus, EGL s can range from three to five times the OEL. In the event of a fire, explosion , or catastrophic emission, the EGLestimates for most of the HCFCs and HFCs and several other chemicals in this sector are based on the lowest - observed - adverse - effect level (LOAEL) or on the no - observed - adverse - effect level (NOAEL) for cardiotoxicity in e pinephrine - sensitized dogs because the primary concern for acute high - level exposure to these compounds is cardiotoxicity . C ardiac sensitization is of particular interest in these acute, episodic exposures because human heart arrh ythmias and sudden death resulting from overexposure to halons, CFCs, and other halogenated h ydrocarbons have been documented in workplace settings and in volatile substance abuse (e.g., glue sniffing). A s defined by

the Agenc y, c ardiotoxicity i s the ability of a compound to caus e serious and sometimes fatal cardiac arrh ythmia, and is best evaluated b y exposing the appropriate species, usuall y the dog, to an agent b y inhalation in the presence of epinephrine (Rubenstein and Bellin 1993). T he Agency is using these values in the SNAP risk screen to ensure protection of the worker population. The protocols used to determine the cardiotoxic LOAEL and NOAEL concentrations for each agent are conservative; they entail measurement of cardiotoxic effects in animals made more sensitive t o these effects by the administration of epinephrine. T he administered doses of epinephrine are just below the concentrations at which epinephrine alone would cause cardiotoxicity

in the experimental animal, and are approximately ten times greater than th e concentration a human being would likel y s ecrete under stress. T hus, the estimated LO AELs and NOAELs would be conservative for humans even in high - stress situations. EPA is adopting OSHA standard (29 CFR 1910, subpart L) section 1910.162 arising from the cardiac sensitization induced by H alon 1301, and is basing its risk assessment decisions for the substitutes that induce cardiotoxicity upon this standard. Under safe use conditions for Halon 1301 (29 CFR 1910.162), the exposure limits, based upon the length of time it takes to evacuate, can be summarized as follows:

$ Where egress takes longer than 30 seconds but less than one minute, the employer shall not use the agent in a concentration greater than its LOAEL for cardiotoxicity (e.g., 100,000 ppm f

or Halon 1301).

$ Agent concentrations greater than the LOAEL for cardiotoxicity are onl y p ermitted in areas not normall y occupied by employees provided that any employee in the area can escape within 30 seconds. T he employer shall assure that no unprote cted employees enter the area during agent discharge.

$ Where egress from an area cannot be accomplished within one minute, the employer shall not use this agent in concentrations exceeding its NOAEL for cardiotoxicity

(e.g., 75,000 ppm for Halon 1301).  17

In addition, EPA recognizes that agents should not be used at a concentration that would significantl y displace oxygen in the lungs. S ince most of the refrigerant substitutes are gaseous, heavier - than - air compounds, following a leak or catastrophic emissi on, they may t end to pool near the ground, (i.e. in the breathing zone). T hese agents are, in the main, colorless with minimal odor and little toxicity

or irritant effect, therefore, they can lead to asphy

xiation by

oxygen displacement, if the unwary pers on inadvertentl y walked into an area of oxygen depletion. Under the SNAP risk screen, EPA is only intending to set conditions for the safe use of refrigerant substitutes in the workplace until OSHA incorporates specific language addressing gaseo us agents into the OSHA regulation. T hese general conditions will no longer appl y once OSHA establishes applicable work place requirements. Where appropriate, the Agency also based its analy sis of short - term exposures to consumers and the general populat ion on these cardiotoxic levels. **3.2 GENERAL POPULATION/CONSUMER (INHALATION) TOXICITY**  **REFERENCE VALUES** For the refrigerants sector, risks to the general population and consumers were screened for short - term and/or long - term exposure scenarios. Risks from short - term exposure were screened using the EGLs and cardiotoxic L OAELs and NOAEL s discussed in the previous section. T his section discusses EPA's general approach for identifying and developing toxicity reference values applicable to chronic (i.e., lifetime) exposure: v erified or interim reference concentrations (RfCs) for noncarcinogens and cancer slope factors (SFs) for carcinogens. **3.2.1 Reference Concentrations (RfCs)**  When possible, the RfC verified b y the Agency's RfD/RfC Work Group, whether or not it has been listed on the Agency 's Integrated Risk Information Sy stem (IRIS) database, was used to assess the risk from long - term exposure to ODS substitutes in the SNAP background assessments. The RfC is designed to protect the general population against adverse s ys temic (i.e., noncancer) effects, and is defined as: "An estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without apprecia

ble risk of deleterious effects during a lifetime. T he inhalation reference concentration is for continuous inhalation exposures and is appropriately e xpressed in units of mg/m 3 " (U.S. EPA 1990). However, when verified RfCs were not available, interim Rf Cs were used to evaluate risks associated with chronic exposure to ODS (listed in decreasing order of preference):

$ Currently

undergoing verification by the Work Group;

$ Not yet undergoing verification but contained in the Agency's Health Effects Asses sment Summary

Tables (HEAST; U.S. EPA 1992);

$ Estimated from other data for the substitute; or  18

$ Estimated based on surrogate limits. The remainder of this section discusses the interim RfCs derived from other data for the substitute or estimated based on surrogate limits. RfCs Estimated From Other Data In the absence of a verified RfC or an RfC pending verification b y the Agency's RfD/RfC Work Group, EPA calculated an interim RfC using the methods specified in EPA's Interim Methods for Development of Inhalation Reference Concentrations (U.S. EPA 1990). S ince adequate human data were not available to calculate RfCs for the proposed substitutes that did not already have RfCs, data obtained from animal inhalation toxicity experiments serve d as the basis for estimating the RfCs. T his approach was adopted in developing an interim RfC for HFC - 143a. For the purposes of the SNAP risk screen, the interim RfC that has been estimated for HFC - 143a was based on limited animal data. T he Agency's Rf D/RfC Work Group reviewed the quality and quantity o f the animal data and determined that the available information was inadequate to derive an RfC. T he compound's interim RfC is, therefore, currently listed as "not verifiable". In general, the verificat ion process requires the existence of a sizeable body o f information. I deall y, this should include two well - conducted chronic inhalation studies, one reproductive study , and two developmental toxicity studies in different species. T he term "not verifiabl e" does not imply that if only

limited data are available that these data are technically deficient. T he Agency

will develop the verified RfC for HFC - 143a when these data become available; use of the interim value should be restricted solely to the SNAP risk screen. If adequate animal inhalation toxicity data were unavailable for a substitute, the interim general population RfC was estimated b y extrapolation from oral references doses (RfDs) or oral NOAELs or LOAELs. A ccording to the Interim Methods for Development of Reference Concentrations , such route - to - route extrapolation can be performed if pharmacokinetic data, including measurements of absorption efficiency and comparative excretion data (when the associated metabolic pathway s are equivalent) are available for both routes of interest, and comparative sy stemic toxicity d ata indicate equivalent effects by e ach route of interest. H owever, the Interim Methods stipulate that oral data should not be used to estimate inhalation exposure limits when the f

ollowing conditions exist: (1) When groups of chemicals are expected to have different toxicity b y the two routes of exposure (e.g., metals, irritants, and sensitizers); (2) When a first - pass effect is expected by the liver, or when the pulmonary s ys tem was not adequatel y studied in the oral studies; (3) When a pulmonary effect is established, but dosimetry comparison cannot be clearl y established between the two routes; and (4) When short - term inhalation studies or in vitro studies indicate potential p ortal - of - entry effects at the lung, but studies themselves are not adequate for RfC development. The appropriate data to assess these conditions were not available for substitutes requiring a route - to - route extrapolation. T herefore, the interim RfCs that were estimated by extrapolation  19

from oral data would most likely be considered "not verifiable" by the Agency's RfD/RfC Work Group. H owever, in the absence of adequate data and in need of a chronic reference toxicity value for the purpose of the SNAP ris k screens, extrapolation from oral data was nevertheless performed according to the following procedures: (1) Oral RfDs (expressed in mg/kg/day) were converted to inhalation RfCs (expressed in mg/m 3 ) by

multiplying the RfD by

the default assumption for av erage human body weight (70 kg) and dividing by the default assumption for average human breathing rate (20 m 3 /day) (EPA 1988). (2) Alternativel y, in the absence of adequate experimental inhalation toxicity data, RfCs for some substitutes were estimated by converting the OEL for that substitute (or a suitable surrogate, as discussed below) to a general population exposure limit. For example, the aliphatic hydrocarbon isobutane is best represented by pentane. The OSHA PEL for pentane is 1,800 mg/m 3

. T hi s value is based on an 8 - hour TWA worker exposure over a 40 - hour work week. T o extrapolate to a threshold for long - term continuous general population exposure, the PEL was multiplied by a factor of 10 m 3 /20 m 3 (assuming that 10 m 3 are inhaled in an 8 - hour day by a healthy worker, extrapolated to 20 m 3 in a 24 - hour day by the general population) (Jarabek and Hasselblad 1991), and then divided by an uncertainty

factor of 1,000 to account for sensitive subpopulations and other uncertainties. Interim RfCs Based on Surrogate Limits For some of the substitutes, there are neither RfCs nor adequate experimental inhalation toxicity data, oral RfDs, oral data, or OELs from which to estimate an RfC. In these cases, exposure limits for a surrogate such as HFC - 134a, the surrogate for several HFCs in this sector, was used. S urrogates were chosen by structure - activity

relationship (SAR) anal ys is to provide the worst - case/most conservative estimate for the exposure limit. S AR is used to predict the biologica l activity

o f an untested compound based on an examination of analogous chemicals with well - documented health or environmental effects data. SAR has been an important tool in guiding the development of new chemicals and drugs for man y ye ars. E PA has used SAR in assessing new chemicals prior to their manufacture or importation under the Premanufacture Notice Program. A lso, the pharmaceutical i ndustry has used SAR to assist in the design and sy nthesis of new drugs.  20

**3.2.2 Cancer Slope Factors**  The cancer slope factor (SF) is used to estimate the upper - bound risk for cancer. B ecause chemicals that produce cancer are assumed not to show a thres hold for their effects, the observed threshold level (i.e., the NOAEL) is not used in the calculation of the cancer SF. R ather, the slope of the dose - response for the effect is used to extrapolate levels at which the risk of the effect is small. It has b een argued that the dose - response function for carcinogenicity could be linear and that it is unlikely

t o exceed linearity

i n the low - dose region. T hus the model chosen to extrapolate low - dose effects from the much higher doses at which effects are observ ed assumes low - dose linearity for cancer production. E PA guidelines (U.S. EPA 1986) recommend that, in absence of adequate information to the contrary , the linearized multistage procedure should be used for the extrapolation. T his model expresses upper c onfidence limits on cancer risk as a linear function of dose in the low - dose range. C ancer SFs are estimated by f itting the model to experimental animal carcinogenicity

data using the maximum likelihood method. In addition, an upper bound on the dose - res ponse curve is calculated, reflecting uncertainty of extrapolating the curve to low doses at which human exposures are anticipated to occur. T his upper bound can be considered to represent the largest reasonable linear extrapolation to low doses consistent with the data. T he 95 percent statistical upper limit on the linear term, q 1 , is referred to as the q 1 *, or the SF. The SNAP cancer risk estimates were based on cancer SFs that have been verified b y EPA's Cancer Risk Assessment Verification Endeavor (C RAVE) Work Group and are contained in IR IS . I f these were unavailable, a second choice was SFs that have not yet been verified but are contained in HEAST (U.S. EPA 1992). T he interim SFs for HCFC - 22 and HCFC - 123 were estimated using raw data from recentl y completed chronic inhalation cancer bioassay s, according to the methods recommended in the EPA Risk Assessment Guidelines (U.S. EPA 1986).  21 **REFERENCES** ACGIH. 1 986. Documentation of the Threshold Limit Values and Biological Exposure Indices . Fifth Edition. ACGIH. 1 992. 1992 - 1993 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . AI HA. 1 989. Concepts and Procedures for the Development of Emergency Response Planning Guidelines (ERPGs) . ERPG Committee. Jarabek, A.M. and V. Hasselblad. 1 991. Inhalation Reference Concentration Methodology: Impact of Dosimetric Adjustments and Future Directions Using the Confidence Profile Method . P resented at 84th Annual Meeting and Exhibition, Van couver, B.C. June 16 - 21, 1991. NI OSH. 1 990. NIOSH Pocket Guide to Chemical Hazards . N IOSH Pub. No. 90 - 117. U S DHHS. NRC. 1 986. Criteria and Methods for Preparing Emergency Exposure Guidance Level (EEGL), Short- term Public Emergency Guidance Level (SPEGL), and Continuous Exposure Guidance Level (CEGL) Documents . C ommittee on Toxicology . N ational Academ y Press, Washington, DC. Rubenstein, R. and J.S. Bellin. 1 993. Short Duration High -Level Exposure to Halon Substitutes: Potential Cardiovascular Effects . P resented at Halon Alternatives Technical Working Conference, Albuquerque, NM, May 11 B 13, 1993. U.S. EPA. 1 992. Health Effects Assessment Summary Tables. A nnual Update. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment. C incinnati, OH. O HEA ECAO - CIN - 821. U.S. EPA. 1 990. Interim Methods for Development of Inhalation Reference Concentrations. Review Draft. August 1990. E nvironmental Criteria and Assessment Office, Office of Health and Environme ntal Assessment, Research Triangle Park, NC. E PA 600/8 - 90/066A. U.S. EPA. 1 988. Recommendations for and Documentation of Biological Values for Use in Risk Assessment . F ebruary 1988. O ffice of Health and Environmental Assessment, Environmental Criteri a and Assessment Office, Cincinnati, OH. U.S. EPA. 1 986. The Risk Assessment Guidelines of 1986 . O ffice of Health and Environmental Assessment. W ashington, DC. E PA/600/8 - 87/045.**4. A**  **TMOSPHERICS MODELING**

**4.1 INTRODUCTION**  EPA has condu cted a risk screen of possible alternatives to Class Iozone depleting substances (ODSs) as part of its implementation of Section 612 of the Clean Air Act Amendments of 1990. C lass I substances include chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform (MCF). C lass I ODSs deplete stratospheric ozone and may contribute to global warming. T hese atmospheric changes have potentially serious consequences for human health and the environment. T he depletion of stratospheric ozone i ncreases the amount of biologicall y active ultraviolet radiation (UV - B) at the earth's surface. Among the consequences of increased UV - B are the increased incidence of cataracts and skin cancers, damage to plants and animals, and damage to poly mers (chemi cal compounds often used in plastics, paints, and coatings). T his chapter presents estimates of the potential atmospheric and human health effects of the alternatives available to replace Class I compounds in the refrigeration and air conditioning sector. The remainder of this chapter is divided into the six following sections: S ection 4.2 presents an overview of the refrigeration and air conditioning sector, including a description of the major end uses; Section 4.3 summarizes the potential replacements for Class Icompounds in the refrigeration and air conditioning sector; Section 4.4 describes the baseline for the analy sis; Section 4.5 details the modeling framework used to quantify the atmospheric and human health impacts of the alternatives; Section 4.6 presents the results of the anal ys is; and Section 4.7 presents a qualitative discussion of global warming and global warming potentials. **4.2 DESCRIPTION OF REFRIGERATION AND AIR CONDITIONING END USES**  CFCs are used as refrigerants in numerous refrigeration and air conditioning applications. For the purposes of this analy sis, the refrigeration and air conditioning sector was divided into several end uses to facilitate appropriate comparisons between possible substitutes. T wo general principles define how equipment ty pes were classified into the various end uses: ( 1) all equipment ty

pes in an end use employ roughly comparable refrigeration technologies (e.g., low and high pressure cold storage warehouse s ys tems are separated ); and (2) all equipment ty pes in an end use serve the same general consumer or industrial purpose (e.g., ice skating rinks and parallel retail food s ys tems form separate end uses). The advantage of this end use classification is that substitutes applicable to a given end u se will ty pically be able to be used in all segments of that end use. Aconsequence, however, is that some end uses are considerabl y larger than others. F or example, all high - pressure industrial process refrigeration s ys tems form one end use, while anoth er end use consists only of CFC - 12 reciprocating chillers. While the principal focus of this analy sis is to evaluate alternatives to Class I substances, many end uses in the refrigeration and air conditioning sector primaril y use HCFC - 22 (a Class II compo und). In order to comprehensivel y examine the health and environmental effects ofsubstitutes throughout this sector, HCFC end uses were anal yz ed in the same manner as CFC end

uses. The end use categories are as follows:

 Retail Food Systems : T hese i nclude stand alone refrigeration cases found in small markets, convenience stores, restaurants and other food establishments, large parallel s ys tems found in supermarkets, and HCFC - 22 sy stems found in a wide variet y of retail and service establishments.

 Cold Storage Sy stems : T hese sy stems refrigerate warehouses of varying sizes and include high pressure and low pressure s ys tems.

 Chillers : T hese are large commercial air conditioning s ys tems used to cool office buildings, shopping malls, and other large indoor spaces. E nd uses modeled are CFC - 11 (low pressure) chillers, CFC - 12 centrifugal chillers, CFC - 12 reciprocating chillers, CFC - 114 centrifugal chillers, and CFC - 500 centrifugal chillers.

 Industrial Process Refrigeration : T hese in clude both packaged and built - up sy stems used in manufacturing processes as well as extra - large ice makers. H igh and low pressure s ys tems are modeled as separate end uses, although the overwhelming majority of industrial process s ys tems are high pressure units.

 Ice Skating Rinks : T here are several different ty pes of ice rink sy stems, but all are grouped into one end use in this analy sis.

 Ice Makers : T hese include small, medium, and large ice makers used by a number of entities, including restaurant s and hotels.

 Household and Li ght Commercial Air Conditioning : T hese include window units, unitary air conditioning sy stems, and heat pumps. A ll sy stems in this end use currentl y use HCFC - 22.

 Refrigerated Appliances : T hese include household refrigerators and freezers, water coolers, vending machines, and dehumidifiers. M ost currentl y use CFC - 12 as a refrigerant, but there are some CFC - 502 units in existence.

 Refrigerated Transport Systems : T hese include sy stems designed to refrigerate materials in transit. T hey are found in trucks, trains, and ships.

 Mobile Air Conditioning : T his end use includes sy stems installed in motor vehicles for the comfort of occupants. Exhibits 4 - 1 and 4 - 2 display the consumption of ODSs in the refrigeratio n and air conditioning sectors as a fraction of total U.S. ODS consumption. T he consumption amounts  24

presented for ODSs in Exhibit 4 - 1 are weighted according to the chemicals' ozone depletion potentials (ODPs). 6

6 Ozone depletion potential (ODP) is a relative index of the ability of a substance to cause ozone depletion. A

r eference level of 1.0 is assigned to CFC - 11 and CFC - 12. Agi ven weight in the atmosphere of a chemical with an ODP of 0. 5 would, in time, deplete half the ozone as the same weight of CFC - 11 or CFC - 12.  25

ex 4 - 1 &4 - 2  26

**4.3 CONTROL OPTIONS**  The alternatives to CFC refrigerants with the widest applicability are HCFC and HFC refrigerants, although other alternatives such as ammonia, propane, and butane are possibilities in some end uses. Whether or not a chemi cal substitute is feasible in a given end use depends on a number of factors, including the required operating temperatures and pressures that need to be attained in that end use. Substitutes can replace CFCs in both new and existing equipment in the refr igeration and air conditioning sector. In general, existing equipment will have to be modified C or retrofitted C to be capable of using the substitutes. In this analy sis, the effects of substitutes in new equipment were distinguished from the effects of the same substitutes as retrofits. T his allows one to study the implications of substitutes in new equipment and existing equipment independentl y from one another. Additional information on possible substitutes, their availability , their potential end u se market penetration, and their impact on energy consumption is presented in Section 4.6 with the results. **4.4 THE BASELINE FOR THE ANALYSIS**  The baseline provides a benchmark against which the effects of possible substitution scenarios can be measured. An appropriate baseline incorporates assumptions regarding chemical emissions in the particular end use being examined, but at the same time it must account for all other sources of emissions of relevant compounds both in the U.S. and in the rest of the w orld (ROW). Aglobal baseline is required because the incremental atmospheric effects of emissions in an end use depend on the quantity em itted from all other end uses worldwide. The baseline is described in three steps. F irst, the uniform assumptions m ade throughout the anal ys is are specified. S econd, the assumptions that are applied to all of the end uses (including end uses in other sectors such as solvents, fire extinguishing, foams, and sterilants) other than the one in which multiple substitutes are being compared are specified. F inally , the baseline assumptions used within an end use when evaluating multiple substitutes are specified. **4.4.1 Uniform Assumptions Made Throughout the Analysis**  This section describes the uniform phaseout and recyclin g assumptions made throughout the anal ys is. T he U.S. phaseout assumptions are listed in Exhibit 4 - 3. T he exhibit lists the last ye ar in which a given chemical can be produced for use in either new equipment or existing equipment. O ther developed countri es (Canada, Japan, Australia, New Zealand, and the nations of Western Europe) are assumed to follow the same schedule. T he phaseout of ODSs in developing countries is assumed to lag that of the developed world b y a decade. In addition, this anal ys is assumes that CFCs and HCFCs are recycled beginning in 1992 during the servicing and disposal of certain refrigeration equipment and that HFCs are likewise recycled starting in 1995. These recycling options are implemented in both the U.S. and the rest of the world (with a ten - ye ar lag for developing countries).  27 **EXHIBIT 4 -**  **3 PRODUCTION PHASEOUT ASSUMPTIONS FOR THE UNITED STATES**  **Chemical Compound Phaseout Date**  **for New Equipment**  **Phaseout Date**

**for Existing Equipment**  CFCs, methyl chloroform and carbon tetrachloride 1996 1996 halons 1994 1994 methyl bromide 2001 2001 HCFC - 141b 2003 2003 HCFC - 22 and HCFC - 142b 2010 2020 All other HCFCs 2015 2030 **4.4.2 Assumptions Made for All Other End Uses**  This section summarizes the substances industry is assumed to choose to replace CFCs, halons and MCF in all end uses other than the one in which multiple substitutes are being compared. A lthough in a few sectors it remains uncertain which substitutes will be chosen, a "best estimate" substitute or combination of substitutes was assumed for each end use under the 1996 phaseout in order to best approximate total worldwide emissions of Class I and Class II substitutes. T hese substitution scenarios were developed based on EPA's best judgment of the likely substitutes to be used in each end use under the 1996 phaseout. **4.4.3 Assumptions Made Within the End Use of Concern**  This section describes the baseline assumptions used within the end use in which multiple substitutes are to be compared. In this anal ys is, two different baselines are used to present the results of the substitution scenarios. B efore detailing these base lines, it is important to note that the choice of the baseline affects the presentation, and not the substance, of the results. Under either of the baselines described below, the relative differences between the substitutes with respect to ozone depletion will be the same. T he absolute results presented for each substitute will, however, differ between the two baselines. Each of the baselines used with the end use of concern are discussed below. O ne is a "no - risk baseline"; the other is a "no - substituti on" baseline. T hese two baselines bound the range of health effects, since the first examines impacts from a risk - free scenario and the second presents effects assuming continued use of all CFCs. **4.4.3.1 Ideal Substitute Baseline**   28

The "ideal" substitute is a hy pothetical alternative that has an ozone depletion potential (ODP) of zero. T he concept of the "ideal" substitute was developed to provide a "no - risk" point of reference from which actual alternatives could be compared against one another. Inthis case, the difference between substitute and baseline scenarios isolates the effects of implementing the substitute in the U.S. relative to an ideal or "no - risk" substitute. A s presented schematicall y in Exhibit 4 - 4, the reported effects of a substitute are the difference between the estimated effects of the substitution scenario and the "ideal" substitute baseline. T he "ideal" substitute baseline consists of the "ideal" substitute in the end use of concern in the U.S. only and the "best estimate" substitute in all other end uses B both in the U.S. and in the rest of the world. The substitution scenario consists of the substitute in the end use of concern in the U.S., and the "best estimate" scenario in all other end uses. In the refrigerat ion and air conditioning sector, special care also has to be taken to distinguish between new and existing equipment, especiall y regarding baseline issues. A s mentioned previously , this analy sis examines separatel y the effects of substitutes in new equipm ent and in retrofits (existing equipment). A s a result, for new equipment scenarios, the anal ys is measures the impact of replacing the ideal substitute with the substitution scenario. T he retrofit scenarios assess the impact of replacing the ideal substi tute in existing equipment with the substitution scenario. **EXHIBIT 4 -**  **4 SUMMARY OF METHODOLOGY USED IN ATMOSPHERICS RUNS**  **TO CALCULATE IMPACTS RELATIVE TO "IDEAL" BASELINE**

**United States Rest**  **- of**  **- World**  End Use of Concern All Other

End Uses End Use

of Concern All Other

End Uses BASELINE SCENARI O "Ideal"

Substitute Best

Estimate Substitute Best

Estimate Substitute Best

Estimate Substitute SUBSTITUTIO N SCENARI O Substitute Best Estimate Substitute Best

Estimate Substitute Best

Estimate Substitute The model includes consideration of speed of market penetration. In all analy ses, the "ideal" substitute fully

penetrates the new equipment market in 1992 and begins to penetrate the existing equipment market in 1992, reaching a maximum market penetration in 2000. T he slower rate of penetration and the smaller final market share for retrofits reflects the behavior that would be expected in practice for most possible retrofit scenarios. A s a result, a substitute that has low ODP but only penetrates that m arket slowl y s hows adverse health effects that are an artifact of the modeling, since until the time the substitute becomes available, Class I compounds must continue to be used.  29

The advantage of the "ideal" substitute baseline is that it allows for a "no - risk" point of reference for presentation purposes but accounts for changes in atmospheric conditions caused by activity in other end uses. It must be emphasized that the "ideal" substitute is only used as a reference point. In all end uses, the relevant comparisons are those between one substitute and another, not between the substitute and the ideal . **4.4.3.2 N**  **o Substitution Baseline** Under this baseline, the incremental perfo rmance of each substitute within an end - use is judged against a no substitution baseline (i.e., continued use of Class I substances within the end use). T his option clearly indicates the reduction in ODP risks associated with replacing the use of Class I compounds with each of the potential substitutes and allows for direct comparisons in risk reduction achievable through each substitute. Inthis case, the difference between substitute and baseline scenarios isolates the effects of implementi ng the substitute in the U.S. relative to a scenario that assumes the continued use of the Class I compound. A s presented schematically in Exhibit 4 - 5, the reported effects of a substitute under this baseline are the difference between the estimated effec ts of the substitution scenario and the no substitution baseline. T he no substitution baseline consists of the continued use of the Class I c ompound in the end use of concern in the U.S. only and the "best estimate" substitute in all other end uses B both in the U.S. and in the rest of the world. T he substitution scenario consists of the substitute in the end use of concern in the U.S., and the "best estimate" scenario in all other end uses. **EXHIBIT 4 -**  **5 SUMMARY OF METHODOLOGY USED IN ATMOSPHERICS RUNS**  **TO CALCULATE IMPACTS RELATIVE TO "NO SUBSTITUTION" BASELINE**

**United States Rest**  **- of**  **- World**  End Use of Concern All Other

End Uses End Use

of Concern All Other

End Uses BASELINE SCENARI O Continued

CFC Use Best

Estimate Substitute Best

Estimate Substitute Best

Estimate Substitute SUBSTITUTIO N SCENARI O Substitute Best Estimate Substitute Best

Estimate Substitute Best

Estimate Substitute As discussed above, this anal ys is examines separately the effects of substitutes in new equipment and in retrofits (existing equipment). A s a result, for new equipment scenarios, the anal ys is measures the impact of phasing out the use of the Class I compound in new equipment in a given end use and replacing it with the sub stitution scenario. T he retrofit scenarios assess the impact of replacing the use of the Class I compound in existing equipment in a given end use and replacing it with the substitution scenario.  30

The intent of the Agency in presenting the resulting of th e tradeoff anal ys is relative to the no substitution baseline is to indicate that all of the substitutes analyzed are substantially less harmful to the ozone layer than continued use of CFCs. In presenting the results in this fashion, however, EPA is cogni zant of the fact that the reduction in ODP risks due to the phaseout of Class I compounds are attributable to the Class I Phaseout Rule and not the Safe Alternatives Program. **4.5 OVERVIEW OF THE MODELING APPROACH**  This section provides a brief description of the Atmospheric and Health Effects Framework (AHEF), the modeling framework used to assess the global environmental impacts of alternatives to Class I substances in the United States. **4.5.1 Chemical Use**  The starting point of an AHEF anal ys is is to forecast the consumption of the relevant chemical compounds in each of the end uses in each sector. F or U.S. estimates, this task is usually performed b y the Vintaging Model, which simulates the chemical requirements of the various equipment ty

pes in each end use over their lifetimes. 7 The Vintaging Model has been used to support several significant Agency rulemakings including the phaseout of Class I and II compounds under Section 604 of the Clean Air Act. It is documented in Appendix A of EPA's Regulatory Impact Analysis: Compliance with Section 604 of the Clean Air Actfor the Phaseout of Ozone Depleting Substances (EPA 1992), which was included in the Phaseout rulemaking docket and was subject to public review and comment. For other regions of the world, chemical use estimates are ty pically d erived by appl yi ng the London Amendment reduction schedule to estimates of what demand would be in the rest of the world had this phaseout never occurred. **4.5.2 Chemical Emissions**  Emissions of a compound into the atmosphere are not necessaril y simultaneous with use. The delay between use and emission of a compound depends on the kind of equipment in which the compound is employed. F or example, hermetically sealed refrigerators emit CFCs over a very long period of time, whereas packaging foam s emit similar compounds in less than one year. AHEF simulates compound emissions by means of release functions which specify the time delay between use and emissions for each particular end use.

7 The data contained in the Vintaging Model were obtained through a series of meetings held by EPA with representatives of the air conditioning and refrigeration industri es during the Spring and Summer of 1991. Q uestionnaires developed at the meetings were analyzed and the information contained reduced to input files in a form usable by the model. A dditional information was obtained from trade associations, professional societies, equipment manufacturers, and from the literature.  31

**4.5.3 Atmospheric Effects**  The output from the emissions m odule are used in an atmospheric model, the Atmospheric Stabilization Framework (ASF), that predicts changes in stratospheric ozone associated with changes in atmospheric composition. A SF computes the globall y and annually averaged concentrations of climatically important atmospheric constituents, taking into account various feedbacks between climate parameters and the constituents themselves. E xamples of feedbacks accounted for in ASF are:

 The dependence of a compound's atmospheric lifetime on column (stratospheric) ozone and temperature;  Radiative and chemical feedbacks due to water vapor;  Ocean absorption;  Atmospheric circulation effects; and  Chemical interactions between compounds. ASF relies on simple empirical relations based either on observations or on the results of more complex models in order to quantify phy sical feedbacks. In particular, the dependence of model ozone on stratospheric chlorine is adjusted so that it predicts a historical ozone depletion equal to that observed for the current atmosphere. In addition, ASF input parameters are adjusted to give column ozone changes that are consistent with consensus ODP estimates. The ASF is a "consensus" model developed b y a committee of prominent atmospheric scientists in government , academia, and private consulting firms. It was designed to approximate the behavior of more sophisticated two and three - dimensional phy sical models without requiring the computing power needed for phy sical simulations. A dditional information on the ASF can be found in National Aeronautics and Space Administration Conference Publication 3023, An Assessment Model for Atmospheric Composition (NASA 1988). **4.5.4 Human Health Effects**  The ozone column changes predicted b y the ASF are inputs to a health effec ts model that estimates the number of skin cancer cases and fatalities that result from the scenario modeled. Estimates of skin cancers include both melanoma and non - melanoma cancers and represent all cases experienced b y individuals born in the United St ates before 2030. In order to quantify

the human health impacts of ozone depletion in the U.S., the globall y averaged ozone depletion predicted b y AS F is converted to estimates of depletion by latitude. This latitudinal variation is estimate d using simple regression techniques from a prior two - dimensional modeling study . (Isaksen, 1986). R esults from a separate UV model are in turn used to estimate changes in UV - B intensit y associated with the latitudinally- varying ozone depletion. Human h ealth effects are computed by AHEF as a function of UV - B exposure. T he effective exposure of various population cohorts, representing different sexes and age groups, is estimated using appropriate factors that weight exposure at various stages during a pe rson's  32

lifetime. E mpirical "dose - response" relationships for each cohort are then used to predict changes in skin cancer and cataract incidence over time. The human health effects model was reviewed in 1987 as part of an EPA Science Advisory Board review of Assessing the Risks of Trace Gases that Can Modify the Stratosphere (EPA, 1987). **4.6 MODEL RESULTS**  This section presents the results of the anal ys is and lists several considerations that are helpful in interpreting them. **4.6.1 Description of Results**  The results are presented in Exhibits 4 - 6 through 4 - 45, one for each end use sector. E ach exhibit contains two tables and two graphs. P arts A and B of each exhibit present the atmospheric results relative to the "ideal" baseline. P arts C and D of each exhibit present the results relative to the no substitution baseline. T he table lists the assumptions regarding the availability and replacement potential of each alternative and estimated atmospheric and health effects resulting from those assumptions. Note that numbers in parenthesis represent decreases from the baseline (e.g., negative numbers). T he graph illustrates the change in cumulative Cl x in 2075 for each of the alternatives. More specificall y, the following information is provided: Start Date : T he ye ar in which the alternative option is expected to be commerciall y available (i.e., after all research and development is complete). Astart date of 1992 indicates that the alternative is currentl y available. Years to Maximum Market Penetration : T he number of ye ars it would take for an alternative, once it became commercially available, to reach its maximum possible use in the end use market. Maximum Market Penetration : T he maximum, technicall y feasible percentage of total ODS consumption in an end use that can be replaced b y the alternative. Cumulative Cl x : T his is a measure of the change in the total quantity of chlorine in the stratosphere over time. M ore technically , it is the integral of the Cl x curve above two parts per billion. Skin Cancer Cases : T he estimated change in the number of cases of melanoma and non - melanoma skin cancers experienced by individuals in the U.S. population born before 2030. The estimate of skin cancers includes fatalities that may result from these cancers. Skin Cancer Fatalities : T he estimated change in the number of fatalities due to melanoma and non - melanoma skin cancers of individuals in the U.S. population born before 2030. S kin cancer fatalities are a small portion of the total number of skin cancer cases. **4.6.2 Interpreting the Results**   33

When interpreting the results, one should be aware of the following:

 For the results presented relative to the ideal baseline, the baseline for the substitution scenarios for new and existing equipment assumes that the "ideal" substitute is fully

implemented in new equipment in 1992 and is retrofit in 50% of existing equipment between 1992 and 2000. A s a result, the numbers presented for each alternative in new equipment scenarios account for: ( 1) the effects of that alternative; (2) the effects of an y continued CFC use occurring in the period after the implementation of the ideal substitute in the baseline and before the implementation of the alternative; and (3) the continued CFC use attributable to the lack of a retrofit. A ccordingl y, the later the availability of the alternative, the greater the quantity of continued CFC use that is attributed to that alternative. Even an ozone - safe alternative can have cancers indirectly attributed to it if it pe netrates the market after the "ideal" substitute.

 Under the ideal baseline, a "no retrofit" scenario (i.e. "ideal" in new equipment and continued CFC use in existing equipment) is included with the retrofit results for each end use to indicate the effec ts of continued CFC use in existing equipment that are potentiall y avoidable through retrofitting. T he results of this scenario are helpful in interpreting both retrofit and non - retrofit graphs because they demonstrate the benefits of retrofitting and sho w how much of the effects in new equipment scenarios can be attributed to the lack of a retrofit.

 Since different HCFCs have different phaseout dates, the total quantity of substitute chemical ultimately released into the atmosphere may differ depending on the alternative. F or example, the results of scenarios using HCFCs with earl y phaseout dates reflect the fact that less of the chemical is ultimately used.

 Blends containing HCFCs are phased out as soon as their earliest constituents are phased out .

 Modeling reflects the market penetration potential for each substitute. T his means that health effects are dependent on potential market size, so that a low ozone - depleting substitute with large market potential could look worse than a high ozone - dep leting substitute with only small uses.  34

Exhibits 4 - 6 through 4 - 45. 80 pages  92

**4.7. Global Warming**  There is no doubt that human activity is increasing the concentration of greenhouse gases in the atmosphere. T he sources and industrial sectors contributing these gases are extremel y varied. N o single economic sector can be held entirely responsible for the greenhouse effect, nor can a single source, because it contributes only a small amount to the problem, be exempt from accountabil ity . A dditional research is needed to better characterize the effects of greenhouse gas emissions on the environment and to evaluate the benefit of various reduction strategies. However, as in the case of ozone depletion, there is growing international c onsensus among scientists and policy

makers that immediate efforts are necessary to curb the rate of growth of atmospheric concentrations of these gases. Based on total emissions, the major greenhouse gases are carbon dioxide (CO 2 ) and methane (CH 4 ), and i t is on these major contributors that EPA has focused much of the effort of its nascent voluntary

p rograms such as Green Li ghts. H owever, a substantial contribution is made in the aggregate b y other gases including CFCs, halons, and other halocarbons. T h ese minor or trace gases are important for two reasons. F irst, although these gases are currentl y emitted in smaller quantities than CO 2 and CH 4 , their effectiveness in influencing climate tends to be greater. Second, while individual use of these gases may add little to the overall burden, the rising concentration of greenhouse gases in the atmosphere cannot be controlled without addressing the aggregate effect of the trace gases. As the transition away from the ozone - depleting compounds proceeds, a key policy go al of the SNAP program in reducing overall risk is to be sure that this shift does not also result in a significant rise in contributions to global warming due to an increased reliance on greenhouse gas substitutes. A lternatives reviewed under S NAP to date have varying potential to contribute to global warming. T heir contribution depends on many factors evaluated under SNAP, including radiative properties and persistence in the atmosphere. It is difficult to make relative judgements among those which do contribute to global warming, however, because their contributions, when viewed through the SNAP lens of individual end - uses, are uniformly small. Recognizing this, SNAP avoids evaluating the viability of greenhouse gases as substitutes based so lel y on a single measure, such as an end - use by end - use contribution to actual warming. Instead, a broader evaluation of a substitute's inherent characteristics, such as its absorption spectra and atmospheric lifetime, is used to help clarify wh ether a su

bstitute could contribute significantl y to the problem relative to other substitutes available. F or example, a compound which might be acceptable in its contribution to global warming in limited uses might become a problem in widespread emissive uses. T hus, a careful review of the volume likely to be used in a particular end - use, and how much is likely to be emitted from that end - use, also helps. F inally , because SNAP's primary

goal is to facilitate the transition away from the ozone - depleting chemicals, a substitute which is also a significant global warming gas might be allowed with controls if there exist few other alternatives in a particular end - use. This section reviews the risk screen for global warming under SNAP. It includes a discussion of the nature of the global warming problem, general properties of greenhouse gases, and global warming resulting from changes in the energy efficiency

of equipment or processes using the alternative chemicals.  93

**4.7.1 The Nature of the Global Warming Problem**  The Earth's stable average temperature is maintained by a radiative balance in which the amount of energy

absorbed from the sun is equal to the amount of energy radiated back into space by the Earth and atmosphere. I f a factor is introduced into the atmosphere that changes this balance, the climate must warm or cool until the radiative fluxes are equal and the balance is restored. Achange of this kind is known as a change in radiative forcing (or warming commitment). R adiative f orcing, expressed in watts per square meter (W/m 2 ), is a measure of the downward radiation flux received b y the climate system. C oncerns about global warming stem from observed increases in the concentrations of certain gases that may be able to alter the climate by causing an increase in radiative forcing. A characteristic that these gases share is that they absorb radiation in the infrared (or thermal) part of the electromagnetic spectrum. M ost of the energy that the Earth receives from the sun is in the form of shortwave radiation in the visible and ultraviolet parts of the spectrum. The energy

e mitted from the Earth to space is in the form of longwave radiation in the infrared part of the spectrum. T hese gases absorb some of the outgoing infrared (o r thermal) radiation and re - emit it both up into space and back down to the Earth. T he net result is a decrease in the heat radiation escaping to space and an increase in the heat radiation falling to the Earth (an increase in radiative forcing). B ecause this process tends to concentrate heat in the troposphere, it is known as the greenhouse effect. T he gases responsible for the greenhouse effect are known as greenhouse gases. Greenhouse gases include carbon dioxide, methane, and nitrous oxide, as well as chlorofluorocarbons (CFCs) and some CFC substitutes. The greenhouse effect is a natural phenomenon which play s an important role in keeping the Earth warm. C oncerns about the greenhouse effect and global warming arise from indications that human activ ities have been increasing the concentrations of both naturally occurring and anthropogenic greenhouse gases. Increasing concentrations of these gases may lead to an enhanced greenhouse effect, which may cause the Earth to warm at a rate much faster than natural rates of climate change. T his accelerated climate change may have a number of adverse consequences including damage to ecosy stems, changes in climatic zones, changes in weather patterns, and sea level rise. A djusting to these changes quickl y may be both difficult and expensive. **4.7.2 Properties of Greenhouse Gases**  All organic compounds that can volatilize into the atmosphere share the property that they absorb energy

in the infrared portion of the electromagnetic spectrum. H owever, these gases do not all absorb infrared radiation equally well, and thus some have greater impacts than others on global warming. T he following factors determine the global warming impact of emissions of a particular gas:

 Atmospheric lifetime. Various phy sical and chemical processes tend to remove and break down chemicals in the atmosphere. Atmospheric lifetime is a measure  94 of how long a gas stays in the atmosphere before it is removed by these processes. 8 The lifetimes of the greenhouse gases are de termined by their sources and sinks in the oceans, atmosphere, and biosphere. In general, the most effective greenhouse gases are those with long lifetimes since the impact of long - lived gases is more persistent than the impact of short - lived gases. In s ome cases this persistence may be cause for concern. W ith very - long - lived gases it may take thousands of years for concentrations to decline significantl y after emissions have stopped. T hus, the impacts these emissions have are essentiall y irreversible.

 Molecular weight. Emissions are t ypicall y measured according to their mass (in kilograms). H owever, the increase in atmospheric concentration (by volume) resulting from an emission is proportional to the number of molecules in the emission, not the to tal mass of the emission. T he number of molecules in an emission of a given mass is inversely proportional to the molecular weight of the gas emitted. A s a result, the molecular weight is needed to determine the increase in concentration resulting from an emission of a given mass. T he lower the molecular weight of the gas, the greater the increase in concentration resulting from a given emission.

 Radiative forcing per molecule. This is a measure of the effectiveness of the gas at absorbing infrared r adiation emitted by the Earth. It is proportional to the increase in radiative forcing resulting from a given increase in concentration. Of these factors, onl y molecular weight is an irreducible characteristic of a gas. Atmospheric lifetime depends on o ther characteristics such as solubility in water, rates of reaction with other components of the atmosphere, and susceptibility to photoly sis. R adiative forcing per molecule depends on a number of characteristics that are relevant to greenhouse gas behavi or. These include the following:

 Integrated infrared band strength. Each kind of molecule absorbs energy at a unique set of wavelengths. T he wavelengths at which a molecule absorbs energy are in patterns of contiguous regions in the electromagnetic s pectrum which are referred to as absorption bands. Amolecule's absorption bands together make up its absorption spectrum. T he strength of the gas's infrared absorption spectrum is a measure of how well molecules of the gas absorb radiation at their characteristic wavelengths (i.e., the stronger the absorption band, the more energy that is absorbed b y the molecule).

8 Atmospheric lifetimes are commonly modeled as e - folding lifetimes. T his means that the concentration of a gas is assumed to decay exponentially. C oncentration through time is given by the following equation: C t = C 0 e - t

L where C t is the concentration at time t, C 0 is the initial concentration, and L is the atmospheric life of the gas. I f the initial concentration of a gas is 1 ppb, its concentration after one lifetime is 1/e (about 0.37) ppb. After two lifetimes the conc entration is 1/e 2 (about 0.14) ppb. In theory this means that the concentration is never truly zero. H owever, after a few lifetimes it does become vanishingly small.  95

 Location of infrared absorption bands. The location of the gas's infrared absorption bands is important for two reasons: F irst, the ener gy radiated from the earth is not evenl y distributed across the infrared spectrum. M ore energy is radiated at some wavelengths than at others. M olecules with absorption bands at wavelengths of high infrared radiation will tend to be more effective greenh ouse gases than molecules with absorption bands at wavelengths of low infrared radiation. S econd, the impact of a greenhouse gas may b e reduced if its absorption bands overlap with those of other gases present in the atmosphere in significant quantities. For example, if a gas has absorption bands that overlap with those of an abundant greenhouse gas like carbon dioxide, the relative impact of the gas on radiative forcing is reduced since much of the energy at these wavelengths is already absorbed.

 Init ial concentration of the gas. If the initial atmospheric concentration of a gas is high enough so that a significant portion of the energy at relevant wavelengths is already absorbed, the impact of additional increases in concentration is reduced. This e ffect is significant for carbon dioxide. It is not significant for CFCs and CFC substitutes since they are present in much smaller quantities than carbon dioxide. R adiative forcing scales linearl y with concentration for these chemicals. A useful index for comparing emissions that incorporates all of these factors is the Global Warming Potential (GWP). T he GWP depends on the position and strength of the absorption bands of the gas, its lifetime in the atmosphere, its molecular weight, and the time period over which the climate effects are of concern. S pecifically , the GWP is defined as the time - integrated change in radiative forcing resulting from a kilogram of emissions of a given chemical relative to the time - integrated change in radiativ e forcing resulting from a kilogram of emissions of a reference gas, t ypically carbon dioxide. 9 Because different gases have different lifetimes, the period of integration has an important impact on relative GWPs. T his point is illustrated by the example of two different gases, each with an initial concentration of 1 ppb. I f the lifetime of the first gas is 10 years, its concentration will be 1/e 10 (0.00005) ppb after 100 ye ars (ten lifetimes). A100 - ye ar GWP captures the entire impact of this gas since the concentration of the gas is effectivel y zero at the end of the period of integration, and it can no longer influence radiative forcing. I f the lifetime of the second gas is 100 years, its concentration will be 1/e (about 0.37) ppb after 100 years (on e lifetime). A 100 - ye ar GWP does not capture the entire impact of this gas since the gas is still present in significant quantities at the end of the period of integration, and it still affects radiative forcing. I f the period of integration were lengthe ned, the ratio of GWPs between the long - lived and the short - lived gases would increase because the value of the integral in the numerator would increase, while the value of the integral in the denominator would remain the same.

9 Climate Change: The IPCC Scientific Assessment. Intergovernmental Panel on Climate Change. 1990.  96

**4.7.3 Properties of ODSs an**  **d ODS Substitutes** Exhibit 4 - 46 presents atmospheric lifetime, molecular weight, integrated infrared band strength and GWPs for a number of ODSs and ODS substitutes. A lthough there is overlap between categories, in general the PFCs have the highest GWPs among ODS substitutes. H FCs are next, followed b y HC FCs, which have the lowest GWPs. P FCs have high GWPs because of their high integrated band strengths and their extremely long atmospheric lifetimes. H CFCs generall y have low GWPs because of their short atmospheric lifetimes (see Exhibit 4 - 46). H FCs ty picall y fall in the middle because of strong integrated band strengths and moderate atmospheric lifetimes. In examining this table the following issues should be considered:

 Although the GWPs of ODSs an d ODS substitutes may be thousands of times the GWP of the reference gas, carbon dioxide, this is offset by the fact that emissions of these compounds are orders of magnitude smaller than emissions of carbon dioxide. N evertheless, it is estimated that CFC s accounted for about 23 percent of the direct radiative forcing from US emissions of greenhouse gases in 1990. 10

 If the lifetime of a chemical is short compared to the lifetime of the reference gas, the GWP of the chemical declines as the period of inte gration increases. I f the lifetime of the chemical is long compared to the lifetime of the reference gas, the GWP of the chemical rises as the period of integration increases. 11

10 This estimate does not account for the indirect atmospheric effect of CFC emissions on radiative forcing. C FCs play a role in the depletion of stratospheric ozone, which is itself a radiatively active gas. Ozone depletion may re duce the net increase in radiative forcing that would otherwise occur as a result of CFC emissions. T his indirect effect does not apply to HFC and PFC emissions, which are not ozone depleting. 11 Because carbon dioxide is removed from the atmosphere through complex processes that cannot be modeled as simple exponential decay, this relationship is not always monotonic.  97

 In practice a high GWP does not necessarily mean a large impact on warming. I f chemicals are never emitted they cannot cause a direct contribution to global warming even if they

h ave high GWPs. F or example, if good service practices are in place, emissions from hermeticall y sealed household refrigerators are very s m all. If the material is recovered for recycling or destruction after the useful life of the equipment, the refrigerant is never released to affect the atmosphere. In contrast, mobile air conditioners tend to be leaky. S ubstitutes used in this end use ar e more likely to be released to the atmosphere and, thus, impact global warming.  98  99

**4.7.4 Indirect Effects from Changes in Energy Efficiency**  In addition to direct and indirect atmospheric effects, ODS substitutes may also have indire ct energy

effects that can influence global warming. U se of alternative chemicals may change the energy

efficiency

of equipment and products currentl y using CFCs. B ecause most energy is derived from burning fossil fuels, changes in energy efficiency

may result in changes in carbon dioxide, nitrous oxide, and methane emissions, which will impact radiative forcing and global warming. T he two major end use categories in which the use of alternatives can impact the energy efficiency

of equipment or products are refrigeration and air conditioning applications and foam insulation applications. T he key factors affecting energy

efficiency

for each of these applications are discussed below. **4.7.4.1 Refrigeration and Air Conditioning End Uses**  Refrigeration and air conditioning equipment can consume significant quantities of energy during normal operation. Whether used in new or existing equipment, a new refrigerant can impact both the energy

efficiency

and cooling capacity

of the refrigeration sy stem. T he spec ific factors that impact the potential change in energy consumption associated with the use of a new refrigerant are as follows:

 Thermodynamic Properties of the Alternative Refrigerant: The thermody namic properties of the refrigerant affect the amount of energy used b y the compressor. 12 This is because these properties determine the evaporating and condensing pressures at which the equipment can operate given the temperature requirements of the application. In practice, the greater the pressure differe nce between the evaporator and the condenser, the more the compressor must work to achieve a given cooling capacity .

 Design of Equipment Components : N ew refrigeration equipment is always designed around the refrigerant to be used. S ys tem components such as the condenser, evaporator, or other heat exchangers are selected to minimize the work that a refrigeration sy stem needs to do given a particular refrigerant. F or example, switching from a CFC to an alternative refrigerant might require a different ty pe of heat exchanger tubing in the evaporator to enhance heat transfer or different sized expansion devices to better control the amount of refrigerant metered to the evaporator.

 Retrofit Optimization : T he use of an alternative refrigerant in existi ng equipment (retrofits) often results in a decrease in the energy efficiency

or refrigerating capacity of the equipment. T his is because the equipment was originall y d esigned to operate most efficiently given the thermodynamic properties of the CFC refri gerant. Anumber of steps can be taken to alter existing equipment so that it operates more efficientl y with a given alternative. S uch steps include changing 12 Components in heating, ventilation, and air conditioning systems that consume energy include fans, pumps, defrost heaters, and compressors. In terms of energy use the component most significantly affected by the refrigerant used is the compressor.  100 the motor drive train, increasing the motor speed, changing the heat exchangers, and replacing the impeller (for chillers). T he gains in energy efficiency associated with such measures must be weighed against cost and possible impact on refrigeration capacity. A widely used measure for the energy efficiency

of refrigeration equipment is the coefficient of performance (COP). T his is defined as the total amount of refrigeration delivered by the equipment divided by the total amount of energy (i.e., work) input into the sy stem. T he COP can be calculated for an ideal cycle. T he COP for an actual piece of equipment can be measured through field testing of the actual energy input and refrigerating effect of the equipment. Field measurements of COP may vary from the ideal COP because of energy losses not accounted for in the model, or variat ions from the ideal cycle caused b y friction losses or pressure drops. Finally , it is important to note that actual changes in energy efficiency

are equipment and application specific. A s a result, it can be difficult to generalize about the potential impacts of a given substitute on energy efficiency

in a given refrigeration or air conditioning application. **4.7.4.2 Foam Insulation**  Several factors combine to limit heat flow in thermal insulating foams including the volume fraction of the solid phase; the cell size which suppresses convection and radiation through cell walls; and the conductivity o f the enclosed cell gases. In addition to the conductivity p er unit volume of the foam, the foam thickness also affects the thermal insulating capacity of foam products. CFCs were highl y suitable as blowing agents in part because their low thermal conductivity

contributed to the insulating capacity of the foam product. S ubstitute blowing agents with higher thermal conductivity contribute less. H igher thermal conductivity of the substitute blowing agent, however, does not necessarily translate into lower energy efficiency

in foam products if formulation or thickness changes are made to compensate for the relative change in substitute blowing agents.  101 **CHAPTER 4 REFERENCES** Is aksen, I.S.A. 1 986. Ozone Perturbation Studies in a Two Dimensional Model with

Temperature Feedbacks in the Stratosphere Included . P resented at the UNEP Workshop on the Control of Chlorofluorocarbons, Leesburg, Virginia. S eptember 1986. National Aeronautics and Space Administration (NASA). 1 989. An Assessment Model for

Atmospheric Composition . N ational Aeronautics and Space Administration Conference Publication 3023. U.S. EPA. 1 992. Regulatory Impact Analysis: Compliance with Section 604 of the Clean Air Act for the Phaseout of Ozone Depleting Substances, Appendix A . O ffice of Air and Radiation. M arch 12, 1992. U.S. EPA. 1 987. Assessing the Risks of Trace Gases that Can Modify the Stratosphere . O ffice of Air and Radiation. D ecember 1987.**5. O**  **CCUPATIONAL EXPOSURE AND HAZARD ANALYSIS 13** 

**5.1 INTRODUCTION**  This section presents an anal ys is of potential occupational exposures to alternative refrigerant materials during the manufacture, installation, repair, and disposal of refrigeration equipment in several end - use sectors. E valuation of potential occupational exposures to these materials was based primarily on the use of a modelling approach that is similar to the approach used by EPA in their previous analy ses of potential occupational exposure to refrigerant vapors (EPA 1990). Where possible, the results obtained from the model were compared to available worker exposure data to determine the direction and magn itude of any uncertainty

resulting from assumptions used in the model. T he following discussion describes the model used to evaluate potential occupational exposures to alternative refrigerants; this is followed by a discussion of the results obtained. **5 .2**  **DESCRIPTION OF THE MODEL** Occupational exposure to a gas or vapor is the result of two events: a release of the material to the air and the presence of a worker within the contaminated space. T he duration and magnitude of the resulting exposure is inf luenced by

(1) the duration and intensity of the release, (2) the rate at which contaminated air is diluted with uncontaminated air in the space affected b y the release, (3) the proximity of the worker to the source of the release, and (4) the length of ti me that the worker remains in the space affected b y the release. The first two factors are addressed directl y b y the mathematics of the "box" model used in this analysis. T his model has been widely used for many years to estimate probable exposures of wo rkers to hazardous airborne materials, and has been described in detail by the National Institute for Occupational Safet y and Health (NIOSH 1973). S tarting with a fundamental material balance, assuming that contaminated air is diluted with uncontaminated air:

Rate of Accumulation = Rate of Generation - Rate of Removal Where: C = Concentration of gas or vapor at time t G = Rate of generation of the contaminant (cubic feet per minute (cfm)) Q'= Effective rate of ventilation that is corrected for incomplete mixing (cfm) V = Volume of room or enclosure (ft 3 ) Converting units and rearranging the equation yi elds the mass balance equation

13 **This analysis was prepared by an industrial hygienist certified by the American Board of Industrial Hygiene.** Where: V = Room Volume (m C i = Indoor Concentration (g/m S = Source Generation Rate (g/hr) r t = Residence Time of the indoor air (hr) m = Mixing Factor (dimensionless) C o = Outdoor Concentration (g/m The integrated form of this equation can be used to calculate the average concentration of a contaminant in a room during the release of a chemical substance:

Where: C b = Concentration already existing in the room when the emission starts (i.e., at time = 0) Assuming that the concentration of contaminant at time = 0 is zero (i.e., C c ontaminated air is diluted with uncontaminated air (i.e., C reached a steady - state (equilibrium) level, the integrated equation above can be further simplified:

A dimension analysis reveals that:

Since it is customary

to measure occupational exposures to gasses and vapors in units of parts per million, the equation above can be modified to:

where MW is the molecular weight of the contaminant.

V = Room Volume (m 3 ) = Indoor Concentration (g/m 3 ) Source Generation Rate (g/hr) = Residence Time of the indoor air (hr) m = Mixing Factor (dimensionless) = Outdoor Concentration (g/m 3 ) The integrated form of this equation can be used to calculate the average concentration of a room during the release of a chemical substance:

= Concentration already existing in the room when the emission starts (i.e., at time = 0) Assuming that the concentration of contaminant at time = 0 is zero (i.e., C ontaminated air is diluted with uncontaminated air (i.e., C o = 0), and that the concentration has

state (equilibrium) level, the integrated equation above can be further simplified:

A dimension analysis reveals that:

Since it is customary

to measure occupational exposures to gasses and vapors in units of parts per million, the equation above can be modified to:

is the molecular weight of the contaminant. The integrated form of this equation can be used to calculate the average concentration of a

Assuming that the concentration of contaminant at time = 0 is zero (i.e., C b = 0), that = 0), and that the concentration has state (equilibrium) level, the integrated equation above can be further simplified:

Since it is customary

to measure occupational exposures to gasses and vapors in units ofBecause the residence time

(ACH), the following can be derived, which is the working equation used to estimate worker exposure to alternative refrigerants:   104 Because the residence time r is the inver se of the air exchange rate in air changes per hour (ACH), the following can be derived, which is the working equation used to estimate worker exposure to alternative refrigerants:  105

However, as described above, the de gree to which a worker is exposed to a gas or vapor also depends on the location of the worker at the time the contaminant is released. T o address this aspect, the use of the box model was modified to recognize the fact that workers move around an area wh ere a release occurs. S pecificall y, the workspace was divided into four areas or zones. These zones are defined as follows:

 Zone 1 represents a space measuring 3' x 3' x 3' centered around an emission source. Aw orker is said to be in Zone 1 whenever his/her breathing zone is within 18 inches of the emission source. T hus, this zone represents an area occupied by a worker performing operations within an arm's reach of the emission source;

 Zone 2 represents a space measuring 12' x 12' x 12' centered around an emission source. Aw orker is said to be in Zone 2 while working within 6 feet of the source;

 Zone 3 represents a space m easuring 30' x 30' x 30' centered around an emission source. Aw orker is considered to be in Zone 3 while working within 15 feet of the emission source; and

 Zone 4 represents a space sufficientl y far from the emission source that no measurable exposure occurs. Thus, refrigerant vapor concentrations will be highest in Zone 1 and will decrease as the worker moves through each zone away from the emission source. U se of this approach captures the idea that there is a vapor concentration gradient surroundi ng the emission source, and that a worker, in the course of performing normal work duties, will move between these zones. A second important assumption concerns the rate at which air is exchanged within each zone. In the implementation of the box model, air within a small space is exchanged at a faster rate than is air within a larger space. T his is due to the presence of local air currents and eddies. In Zone 1, which is the smallest space defined in the model, the motion of the worker's hands and tool s will serve to increase the rate of air exchange; however, in a larger space, local air currents will have a lesser effect on the overall rate of air exchange within that space. A s such, the air within a 3' x 3' x 3' space may be exchanging with surround ing air at a rate of 30 air changes per hour (ACH) even though the overall rate of air exchange within a 30' x 30' x 30' room is only 0.5 ACH. In the model, it is assumed that air within Zone 1 is moving through the zone at a rate of about 2 mph. T his rate is cut in half for Zone 2, and by 75 percent in Zone 3. T he rate of air movement within Zone 3 is equivalent to about 50 feet per minute, which represents a background rate of air movement frequently seen in industrial facilities having moderate genera l dilution ventilation. Amixing factor of 0.5 is assumed, which cuts the effective air exchange rate in half. Thus, to implement the box model, the variables in the working equation above were substituted as follows. T he variable S is the release rate in g/hr. T he value of S was derived from the Vintaging model used to estimate refrigerant release rates for various release scenarios. T he release rate per event (from the Vintaging model) was multiplied by the number of events estim ated to occur over a workday . F or equipment manufacturing, the number of events per workday was assumed to equal the number of units produced per plant per year divided by 365 day s per year. F or scenarios where fewer than 365 units are manufactured per year, it is assumed that the event causing the emission occurs over a single 8 - hour workday , rather than over several day s. F or installation and repair operations, it is assumed that one event occurs per workday for large refrigeration s ys tems and four eve nts per workday for small s ys tems. F or disposaloperations involving refrigerators and freezers, other refrigeration appliances, and mobile air

conditioners, it is assumed that 100 units are disposed of over an 8 end - use sectors , it is assumed that one unit is disposed of during a single shift. The variable V represents the volume of space in which the worker is performing his or her work duties. F or each exposure scenario, it is assumed that a worker spends a certain p of time within each of the four zones, as follows. F or manufacturing and installation operations, it is assumed that a worker spends 10 50 percent in Zone 2, 30 percent in Zone 3, and assumed that a worker spends 20 percent of the workday in Zone 1, 40 percent in Zone 2, 20 percent in Zone 3, and 20 percent in Zone 4; this reflects the likely possibility that, in repair operations as c ompared to manufacturing or installation operations, a worker will spend a larger proportion of the workday in close proximity

to the emission source, but will also spend a greater proportion of the day

away from the emission source while travelling to the After using the box model to estimate the average vapor concentration within each zone, a worker's 8 - hour time - weighted - average exposure is calculated as follows: where C x = Concentration of vapor within Zone x; and P x = Percent of time spent in Zone x by the worker. The term representing Zone 4 drops out because there is no exposure to refrigerant vapors in Zone 4 (by definition). To estimate short - term (i.e., 30 it is assumed that 25 percent of the daily emission is released over a 30 **5.3 DISCUSSION OF RESULTS**  **5.3.1 Presentation of Results**  The attached tables (Attachment 5 work operati on, and alternative refrigerant. F or each scenario, the tables report the average 8 - hour and 30 - minute time - weighted average (TWA) concentrations of refrigerant present in each of the zones, and the estimated 8 exposed. Exhibit 5 - 1 summarizes the occupational exposure limits for the alternative refrigerants that were used to determine whether workers may be exposed to potentially hazardous airborne gas or vapor concentrations. E xhibit 5 model suggests that worker exposures may exceed either the 8 exposure limit for the alternative refrigerant. T he highest exposures are predicted to occur during the manufacturing and disposing of industrial process (high pressure build sy stems. **5.3.2 Interpretation and Comparison of Model Results with Sampling Data**    106 operations involving refrigerators and freezers, other refrigeration appliances, and mobile air conditioners, it is assumed that 100 units are disposed of over an 8 - hour shift. F or all other

, it is assumed that one unit is disposed of during a single shift. represents the volume of space in which the worker is performing his or her work duties. F or each exposure scenario, it is assumed that a worker spends a certain p of time within each of the four zones, as follows. F or manufacturing and installation operations, it is assumed that a worker spends 10 percent of his or her time over an 8 - hour workday i n Zone 1, 50 percent in Zone 2, 30 percent in Zone 3, and 10 percent in Zone 4. F or repair operations, it is assumed that a worker spends 20 percent of the workday in Zone 1, 40 percent in Zone 2, 20 percent in Zone 3, and 20 percent in Zone 4; this reflects the likely possibility that, in repair

ompared to manufacturing or installation operations, a worker will spend a larger proportion of the workday in close proximity

to the emission source, but will also spend a greater proportion of the day

away from the emission source while travelling to the repair site. After using the box model to estimate the average vapor concentration within each zone, a

average exposure is calculated as follows: = Concentration of vapor within Zone x; and = Percent of time spent in Zone x by the worker. The term representing Zone 4 drops out because there is no exposure to refrigerant vapors in Zone term (i.e., 30 - minute) worker exposures to refrigerant vapors and gas it is assumed that 25 percent of the daily emission is released over a 30 - minute period. **DISCUSSION OF RESULTS** The attached tables (Attachment 5 - A) show the modelling results for each end on, and alternative refrigerant. F or each scenario, the tables report the average

weighted average (TWA) concentrations of refrigerant present in each of the zones, and the estimated 8 - hour and 30 - minute TWA levels to which worke

1 summarizes the occupational exposure limits for the alternative refrigerants that were used to determine whether workers may be exposed to potentially hazardous airborne gas or vapor concentrations. E xhibit 5 - 2 summarizes the results for those scenarios where the model suggests that worker exposures may exceed either the 8 - hour or 30 - minute occupational exposure limit for the alternative refrigerant. T he highest exposures are predicted to occur during

disposing of industrial process (high pressure build - up) refrigeration **Interpretation and Comparison of Model Results with Sampling Data** operations involving refrigerators and freezers, other refrigeration appliances, and mobile air hour shift. F or all other represents the volume of space in which the worker is performing his or her work duties. F or each exposure scenario, it is assumed that a worker spends a certain p ercentage of time within each of the four zones, as follows. F or manufacturing and installation operations, hour workday

i n Zone 1, 10 percent in Zone 4. F or repair operations, it is assumed that a worker spends 20 percent of the workday in Zone 1, 40 percent in Zone 2, 20 percent in Zone 3, and 20 percent in Zone 4; this reflects the likely possibility that, in repair

ompared to manufacturing or installation operations, a worker will spend a larger proportion of the workday in close proximity

to the emission source, but will also spend a greater repair site. After using the box model to estimate the average vapor concentration within each zone, a

The term representing Zone 4 drops out because there is no exposure to refrigerant vapors in Zone minute) worker exposures to refrigerant vapors and gas ses, minute period.

A) show the modelling results for each end - use sector, on, and alternative refrigerant. F or each scenario, the tables report the average

weighted average (TWA) concentrations of refrigerant present in each

minute TWA levels to which worke rs may be 1 summarizes the occupational exposure limits for the alternative refrigerants that were used to determine whether workers may be exposed to potentially hazardous airborne he results for those scenarios where the

minute occupational exposure limit for the alternative refrigerant. T he highest exposures are predicted to occur during up) refrigeration **Interpretation and Comparison of Model Results with Sampling Data**  107

Several observations suggest that the model will tend to overstate likel y occupational exposures to al ternative refrigerant vapors and gasses. F irst, the emission estimates from the  108 **EXHIBIT 5 -**  **1 OCCUPATIONAL EXPOSURE LIMITS FOR**  **POTENTIAL ALTERNATIVE REFRIGERANTS*** Substitute Material WGL(ppm) EGL(ppm) HCFC - 22 1,000 5,000 HFC - 23 1,000 3,000 HCFC - 123 30 2,500 HCFC - 124 1,000 3,000 HFC - 125 1,000 3,000 HFC - 134a 1,000 3,000 HFC - 143a 1,000 3,000 HCFC - 142b 1,000 5,000 HFC - 152a 1,000 4,000 HFC - 227ea 1,000 3,000 * T his table may

contain or utilize exposure limits that are not Agency verified or that were updated after this chapter was written. C hapter 3 presents the most recent exposure limits for each chemical, identifies which are verified versus estimated values, identifies methods used to derive estimated values, and provi des information sources. Vintaging model are considered to be worst - case estimates. S econd, the assumptions regarding air exchange rates for each of the work zones do not reflect the use of any l ocal exhaust ventilation, which is likely

to be used in m anufacturing and disposal operations involving any significant releases. The use of properl y designed local exhaust ventilation or other means of isolating the worker from emission sources would likel y prevent gas or vapor concentrations from exceeding th e occupational exposure limits most of the time. G iven the assumed sizes of many of the potential releases (some of them exceeding a few hundred pounds), it would appear unlikel y that an employer would conduct such operations without providing some means of mechanical ventilation. It is for this reason that the exposure estimates for high - pressure industrial process refrigeration sy stems are certain to be unrealistically high. In addition, for each release scenario, it is assumed that the entire estimate d dail y release occurs over a single 8 - hour workday and at a single location. T his is not the case for many scenarios, and particularl y for manufacturing operations, where the estimated daily release may occur over two or three workshifts or where the rel ease may

be spread out over two or more production lines. F inally , most of the predicted exceedances over the occupational exposure limits are the result of assuming that there will be no recycling of HFC refrigerants. T o the extent that recycling techno logies are used, exposures to HFCs should be below the occupational exposure limits for these compounds. The model's tendency to overstate worker exposures is further supported b y sampling data obtained for HCFC - 123 refrigerant during repair operations co nducted on low - pressure  109 **EXHIBIT 5 -**  **2 SUMMARY OF ESTIMATED WORKER EXPOSURE TO ALTERNATIVE REFRIGERANTS**  **FOR SCENARIOS WHERE THE OCCUPATIONAL EXPOSURE LIMIT IS EXCEEDED** a 8 - Hour TWAb 30 - Minute TWA End - Use Sector Operation Substitute Material c Predicted

Exposure (ppm) Operation Substitute Material c Predicted

Exposure (ppm) Retail Food (Parallel Sy stem) Disposal HFC - 134a HFC - 125 HFC - 143a HFC - 23 1,579 1,342 1,917 2,300 Disposal HFC134a HFC - 125 HFC143a HFC - 23 4,742 4,030 5,757 6,909 Cold Storage Warehouses Disposal HFC - 152a HFC - 23 1,309 1,234 Centrifugal Chillers (Low Pressure) Manufacture HCFC - 123 73 d Centrifugal Chillers (High Pressure) Disposal HFC - 124 HFC - 134a HFC - 227ea 2,271 3,050 1,647 Disposal HFC - 124 HFC - 134a HFC - 227ea 6,819 9,159 4,928 Industrial Process (Low Pressure) Manufacture Repair HCFC - 123

HCFC - 123 54 49  110 **EXHIBIT 5 -**  **2 (continued) SUMMARY OF ESTIMATED WORKER EXPOSURE TO ALTERNATIVE REFRIGERANTS**  **FOR SCENARIOS WHERE THE OCCUPATIONAL EXPOSURE LIMIT IS EXCEEDED**  a 8 - Hour TWAb 30 - Minute TWA End - Use Sector Operation Substitute Material c Predicted

Exposure (ppm) Operation Substitute Material c Predicted

Exposure (ppm) Industrial Process (High Pressure Build - Up) Manufacture Disposal HFC - 143a

HFC - 152a HFC - 134a HFC - 152a HFC - 125 HFC - 143a HFC - 23 1,293 1,016 30,840 47,661 15,740 18,375 13,490 Manufacture Disposal HFC - 134a

HFC - 143a HFC - 152a HFC - 134a HFC - 152a HFC - 125 HFC - 143a HFC - 23 3,941 7,751 6,090 92,608 143,122 47,266 56,260 40,509 Large Ice Makers Repair HFC - 152a 1,076 Ice Rinks Disposal HFC - 134a HFC - 152a HFC - 23 4,609 7,123 2,016 Disposal HFC - 134a HFC - 152a HFC - 23 13,840 21,390 6,054 Central A/C and Home Heat Pumps Manufacture HFC - 152a 1,332

a Exposure levels are rounded to the nearest whole number. b Time - weighted average. c The refrigerant blends analyzed for these sectors may b e considered confidential business information (CBI) by the manufactur er. A s a result, the identification of the constituents of any blend and the proportion of each constituent contained in any blend are not presented in this exhibit. d One manufacturer's representative states that worker exposures to HCFC - 123 during centrifugal chiller manufacture are ty pically 1 p pm or less, due to the use of exh aust ventilation.  111

centrifugal chillers (EPA 1991). T his study showed that worker exposures were generally well below 1 ppm as an 8 - hour TWA during repair operations involving the use of recycling equipment; however, results from the model suggest that workers may be exposed to about 4 ppm HCFC - 123 during these repair operations, even when proper recycling is used. F or the manufacture of low - pressure centrifugal chillers, the model suggests that workers could be exposed to HCFC - 123 concentrations as high as 73 ppm as an 8 - hour TWA; however, a representative of one manufacturer indicated that, due to the use of local exhaust ventilation, worker exposures were ty picall y in the range of 1 ppm (personal communication). The anal ys es presented above did not consider the use of ammonia, butane, propane, or perfluoropropane as alternative refrigerants. H owever, existing OSHA and ASHRAE standards governing the handling and use of these materials should serve to limit occupational exposures to them . C urrently , OSHA enforces permissible exposure limits (PEL s) for two of these materials: ammonia (50 ppm as an 8 - hour TWA), and propane (1000 ppm as an 8 - hour TWA). In addition, ASHRAE classifies butane and propane as "highly flammable" refrigerants, an d ammonia as a "moderatel y f

lammable" refrigerant having high toxicity ( ASHRAE Standard 34); as such, special requirements set forth in ASHRAE Standard 15 apply to the use of these materials as refrigerants. These requirements include:

 Prohibiting the use of any of these refrigerants in sy stems designed for human comfort;

 Limiting the amount of refrigerant that can be used in systems installed in occupied areas;

 Requiring the use of vapor detection alarms that activate when concentrations of refri gerant exceed toxic or explosive levels; and

 Prohibiting the use of butane or propane in an y s ys tem installed in commercial or institutional buildings (i.e., only industrial use is permitted). **5.4 POTENTIAL WORKPLACE FLAMMABILITY AND EXPLOSIVITY RISKS**  One of the alternative refrigerants considered in this analy sis, HFC - 152a, has been classified as a moderately flammable material under proposed ASHRAE Standard 34. It has a lower flammabilit y l imit (LFL) of 4.4 percent in air (44,000 ppm) and a heat of combustion of less than 19,000 kJ/kg. A s such, it represents a lesser fire and explosion risk than propane or butane, which have LFL's that are less than half that of HFC - 152a and heats of combustion greater than 19,000 kJ/kg. The risk of fire or explosi on in an industrial setting arises when local concentrations of a flammable or explosive gas or vapor are allowed to exceed the lower flammable limit for the gas or vapor in the presence of an ignition source (i.e., flame, heat, electrical energy, or stati c sparks). In general, when handling flammable or explosive materials, most industrial facilities consider that accumulations of gas or vapor concentrations of from 10 to 25 percent of the LF L or higher for that substance represent an emergency situation that requires corrective action. F or HFC - 152a, an emergency

concentration would therefore be considered to exist if concentrations exceeded 4,400 to 11,000 ppm (i.e., 10 to 25 percent of the LFL).  112

The exposure assessment anal ys is presented above shows that, under worst - case assumptions and assuming no recycling, local short - term concentrations of HFC - 152a would not be expected to exceed 4,400 ppm under normal operating conditions in all but one end - use sector (high - pressure industrial process refrig eration). A s stated above, EPA believes that the exposure estimates for this end - use sector are unrealistically high because of the assumption that no mechanical ventilation would be used during operations involving the release of such large quantities of refrigerant. T hus, with the appropriate use of equipment designed for the safe use of flammable or explosive gases and with the use of mechanical ventilation systems, concentrations of HFC - 152a are not likely to exceed 10 percent of the LFL and should therefore not present a substantial fire or explosion risk in the workplace. I solation of potential ignition sources (such as welding operations conducted on the assembl y line) from processes involving the handling of HFC - 152a, and the use of combustible gas detectors and alarm s ys tems, will serve to further reduce this potential risk.  113 **CHAPTER 5 REFERENCES** NI OSH (Mutchler, J.E.) 1 973. " Principles of Ventilation." The Industrial Environment--It's

Evaluation and Control . N IOSH, Center for Dis ease Control, U.S. Department of Health and Human Services. c h. 39. U.S. EPA. 1 990. Revised Draft: O ccupational Exposure and Environmental Release Data for Chlorofluorocarbons (CFCs) and Their Substitutes . O ffice of Toxic Substances. U.S. EPA. 1 991. Results of Employee Exposure Monitoring for HCFC - 123 at Centrifugal Chiller Installations . F inal Report. N ovember, 1991.**ATTACHMENT 5 -**  **A 6.**  **C ONSUMER EXPOSURE AND RISK SCREENING ANALYSIS** 

This chapter presents a screening level assessment of the risks to consumers from releases of CFC substitutes used in home appliances (refrigerators and freezers, central air conditioners, window air conditioners, and miscellaneous refrigerated appliances) and automobile air conditioners. T hese are the only applications in the refrigeration and air conditioning sectors that have consumer end uses. The end uses and substitutes evaluated in this chapter are presented below. T he composition of one -- R200 b -- is confidential:

 Refrigerators and Freezers:

C HCFC - 22

C HFC - 134a

C HFC - 152a

C HCFC - 22/HCFC - 142b

C HCFC - 22/HFC - 152a/HCFC - 124

C R200b

 Dehumidifiers: Same as refrigerators and freezers.

 Central Air Conditioners and Home Heat Pumps:

C HFC - 125

C HFC - 134a

C HFC - 125/HFC - 143a

C HFC - 23/HFC - 134a

C HFC - 125/HFC - 143a/HFC - 134a

C HCFC - 22/propane/HFC - 125

 Window Air Conditioners:

C HFC - 125

C HFC - 134a

C HFC - 125/HFC - 143a

C HFC - 23/HFC - 134a

 Mobile Air Conditioners:

C HFC - 134a

C HCFC - 22/HFC - 152a/HCFC - 1 24 This chapter first presents an assessment of consumer exposure to releases from home appliances, followed b y an anal ys is for mobile air conditioners. T he anal yses performed are screening anal ys es whose purpose is to identify the proposed substitutes for a ll end uses that may pose an y potential concern for human health or environmental risk. A s a result, the anal ys esemploy

conservative assumptions that tend to overestimate potential risk. C onsiderable uncertainty exists in these anal ys es.  117

**6.1 HO**  **ME APPLIANCES** Three t ypes of releases from home appliances are of interest for consumer exposure and risk: ( 1) routine operating leakage, (2) releases during servicing, and (3) accidental releases. A report on consumer exposure to CFCs and their subst itutes prepared for EPA (Versar 1990) examined exposures from leakage and servicing releases from refrigerators, freezers, and dehumidifiers. U sing engineering estimates of releases as input to an equation given on page 4 - 5 of this report, average annual concentrations of CFC substitutes were calculated in median - sized and 10th percentile - sized homes. B ecause this consumer exposure anal ys is spreads the releases and resulting concentrations over a ye ar's time, it assesses onl y long - term, chronic exposures. It does not address potential risks from short - term exposure to higher concentrations that result from servicing or accidental releases. Below, potential risks from chronic exposures are examined by c omparing estimated doses from the consumer exposure r eport to toxicity values for the CFC substitutes. S ubsequently , a screening anal ys is of potential risks associated with higher, but shorter - term, exposures is presented. F inall y, potential safet y concerns from the use of HFC - 152a in household refrigerato rs are discussed. **6.1.1 Risks from Long**  **- term Exposure to Leakage and Servicing Events**  C **Previous Estimates**  The consumer exposure report estimated releases from refrigerators, freezers, and dehumidifiers with refrigerant charge sizes ranging from about 14 0 to 570 g. T he annual leakage rate was assumed to be 0.2 percent of the charge (0.28 to 1.1 g), and the servicing emission was assumed to be 85 g. The estimated average annual concentrations in two different house sizes C a median size of 411 m 3 (equiva lent to 1,808 ft2 , assuming an 8 - ft ceiling height) and a 10th percentile size of 174 m 3 (766 ft2 , assuming an 8 - ft ceiling) 14

C ranged from 0.4 μ g/m 3 to 3.7 μ g/m 3 for annual leakage. To estimate potential risk from chronic exposure to leakage, the consumer exposure report's exposure information was combined with available toxicity information as follows:

 To evaluate noncarcinogenic effects, the modeled exposure concentrations were compared to reference concentrations (RfCs).

 To calculate cancer risks, a lifetime average daily dose of the substitute was estimated using the exposure concentration, a 20 m 3 /day inhalation rate, and a 70 kg body weight. The RfCs and cancer slope factor used in this assessment are given in Chapter 3 of this document. The highest estimated average annual exposure for routine leakage from the consumer exposure report C 3.7 μ g/m 3

C is well below the RfCs for all substitutes. O nly on e of the substitutes C HCFC - 22 C is a possible carcinogen. A ssuming that people are exposed to an

14 The consumer exposure report prepared by Versar also assumed a ventilation rate of 0.2 ACH, that is, 0.2 air exchanges per hour.  118

HCFC - 22 concentration of 3.7 μ g/m 3 24 hours per day, 365 days p er year, over a 70 - year lifetime, the cancer risk for HCFC - 22 is 2.1E - 07. 15 Based on EPA guide lines regarding levels of risk, chronic health effects from long - term exposure to routine leakage of CFC substitutes from home appliances are not of concern.

15 In this chapter, where numeric notation is used that includes the term "E - 0 x " (for example, 2.1E - 07), it is equivalent to 10 - x (fo r example, 2.1 x 10 - 7 ).  119

The consumer exposure report estimated the typical servicing emissions from all pieces of equipment to be 85 grams per service. D uring a year in which the equipment is serviced once, the report calculated average annual concentrations ranged from 118 μ g/m 3 for a median - sized house to 279 μ g/m 3 for a house sized in the 10th percentile. T hese are also well below the RfCs for the substitutes. I f it is assumed that servicing occurs once every year and that people spend all of their time at home, the cancer risk associated with lifetime exposure to HCFC - 22 would be 6.7E - 06 in the median house and 1.6E - 05 in the smaller house. H owever, these values overstate potential cancer risks because (1) home appliances such as refrigerators, freezers, and humidifiers ar e serviced much less frequently than once a year; and (2) people typically do not spend all of their time at home. G iven these factors, EPA believes that actual cancer risks are well below 10 - 5 , the threshold level of concern. **6.1.2 Risks from Short**  **- term**  **Exposure During Servicing and Accidental Releases** The next step was to examine potential health risks from short - term exposure to temporaril y higher concentrations associated with servicing emissions and accidental releases. Four situations were examine d:

 Exposure to vapors from refrigerators or freezers located in the kitchen;

 Exposure to vapors from a dehumidifier located in a room;

 Exposure to vapors from a central air conditioner or heat pump, where the release occurs in the basement; and

 Exposure to vapors from a window air conditioner located in a room. Approach To simulate the initial increase and subsequent decrease in airborne concentrations resulting from refrigerant releases, the same "box model" approach was used as in the previous anal ys is of occupational exposure (see Chapter 5). T his model was derived from a differential material balance that, when integrated, provides a basis for relating the air concentration of a contaminant to the generation and removal rates of the contaminant. To calculate releases, it was assumed that the amount of substitute re leased was equal to the amount of CFC released. C FC release information was derived from input files to the Vintaging Model. 16 The following assumptions concerning releases were made for this analysis:

 Servicing releases occur over 15 minutes. H CFCs are recycled at servicing (under Section 608 of the Clean Air Act, HCFC recycling became mandatory in 1992). Because HFC recycling will not be mandatory until 1995, servicing releases for HFCs are calculated both with and wi thout recycling. I f there is no recycling, the entire charge is released. T he releases are as follows:

16 The Vintaging Model was developed by ICF to estimate the costs and environmental releases associated with a CFC and halon phaseout. F or further information, see Chapter 4.  120 Recycling No Recycling Refrigerators and Freezers 15 g 300 g Dehumidifiers 20 g 400 g Central A/Cs and Heat Pumps 80 g 3,840 g Window Air Conditioners 40 g 1,820 g

 Accidental releases are modeled as leakage of the entire charge over two different time frames: 1 5 minutes and four hours. T he releases are the same as those listed above under the "no recycling" scenario. The following inputs were made to the box model:

 Room sizes :

C 411 m 3 for house volume (equivalent to 1,808 ft2 , assuming an 8 - ft ceiling height);

C 18 m 3 (79 ft2 ) for the kitchen;

C 102 m 3 (449 ft2 ) for the basement; and

C 41 m 3 (180 ft2 ) for the room housing the window A/C or miscellaneous unit.

 Air exchange rate :

C 0.25 air changes per hour (ACH) for the house, basement, and room; and

C 2.3 ACH for the kitchen. Thirty minute time weighted average (TWA) exposures wer e calculated and compared to the interim emergency

guidance levels (EGLs) shown in Chapter 3. Results Exhibits 6 - 1 through 6 - 4 show the 30 minute average concentrations and their ratios to the interim EGL s for the relevant substitutes. ( The values shown in these tables are based on the substitute being composed of 100 percent of the named chemical. In practice, some substitutes would be used onl y in a blend.) T he results are discussed below. The results show that servicing with recycling never results in concentrations above the EGL . A ll of the other scenarios involve release of the entire charge. T his can result from an accident or C for the HFCs only C from a servicing event that does not involve recycling. T he modeling indicates that, unless othe rwise noted, the concentrations of the following substitutes or combinations of substitutes never exceed the EGL even if the entire charge is released:

 Refrigerators and freezers:

C HCFC - 22;

C HFC - 134a;

C HFC - 152a;  121 **EXHIBIT 6 -**  **1 30**  **- MINUTE**  **AVERAGE CONCENTRATIONS FROM SERVICING AND ACCIDENTAL RELEASES, AND RATIO TO**  **INTERIM EMERGENCY GUIDANCE LEVELS (EGLs):**

**REFRIGERATORS AND FREEZERS** Service, With Recycling Service,

Without Recycling Accidental

15 - Min. Release Accidental

4 - Hr Release KI TCHEN 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HCFC - 124 HCFC - 142b HFC - 134a HFC - 152a HFC - 227ea 430

0.025 0.025 0.022 0.034 0.032 0.020 10,000

NA NA NA 0.79 0.74 0.48 10,000

0.57 0.58 0.50 0.79 0.74 0.48 3,300

0.19 0.19 0.17 0.26 0.24 0.16 HOUSE 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HCFC - 124 HCFC - 142b HFC - 134a HFC - 152a HFC - 227ea 24

0.0014 0.0014 0.0012 0.0019 0.0018 0.0011 550

NA NA NA 0.044 0.041 0.026 550

0.031 0.032 0.028 0.044 0.041 0.026 570

0.033 0.033 0.029 0.045 0.042 0.027  122 **EXHIBIT 6 -**  **2 30**  **- MINUTE AVERAGE CONCENTRATIONS FROM SERVICING**  **AND ACCIDENTAL RELEASES, AND RATIO TO INTERIM EMERGENCY GUIDANCE LEVELS (EGLs):** 

**DEHUMIDIFIERS** Service, With Recycling Service,

Without Recycling Accidental

15 - Min. Release Accidental

4 - Hr Release ROOM 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HCFC - 124 HCFC - 142b HFC - 134a HFC - 152a HFC - 227ea 440

0.025 0.026 0.022 0.035 0.033 0.021 6,100

NA NA NA 0.48 0.45 0.29 6,100

0.35 0.36 0.31 0.48 0.45 0.29 6,400

0.37 0.37 0.32 0.51 0.47 0.30 HOUSE 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HCFC - 124 HCFC - 142b HFC - 134a HFC - 152a HFC - 227ea 42

0.0024 0.0025 0.0021 0.0033 0.0031 0.0020 610

NA NA NA 0.048 0.045 0.029 610

0.035 0.036 0.031 0.048 0.045 0.029 630

0.036 0.037 0.032 0.050 0.047 0.030  123 **EXHIBIT 6 -**  **3 30**  **- MINUTE AVERAGE**  **CONCENTRATIONS FROM SERVICING AND ACCIDENTAL RELEASES, AND RATIO TO**  **INTERIM EMERGENCY GUIDANCE LEVELS (EGLs): CENTRAL AIR CONDITIONERS AND HOME HEAT PUMPS** 

Service, With Recycling Service,

Without Recycling Accidental

15 - Min. Release Accidental

4 - Hr Relea se BASEMENT 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HFC - 23 HFC - 125 HFC - 134a HFC - 143a 590

0.034 0.069 0.040 0.047 0.058 28,000

NA 3.3 1.9 2.2 2.7 28,000

1.6 3.3 1.9 2.2 2.7 29,000

1.7 3.4 2.0 2.3 2.8 HOUSE 30 - Min. TWA, mg/m 3 Ratio to EGL : HCFC - 22 HFC - 23 HFC - 125 HFC - 134a HFC - 143a 150

0.0086 0.018 0.010 0.012 0.015 7,000

NA 0.82 0.48 0.56 0.69 7,000

0.40 0.82 0.48 0.56 0.69 7,200

0.41 0.84 0.49 0.57 0.71  124 **EXHIBIT 6 -**  **4 30**  **- MINUTE**  **AVERAGE CONCENTRATIONS FROM SERVICING AND ACCIDENTAL RELEASES, AND RATIO TO**  **INTERIM EMERGENCY GUIDANCE LEVELS (EGLs):**

**WINDOW AIR CONDITIONERS** Service, With Recycling Service,

Without Recycling Accidental

15 - Min. Release Accidental

4 - Hr Release ROOM 30 - Min. TWA, mg/m 3 Ratio to EGL : HFC - 23 HFC - 125 HFC - 134a HFC - 143a 740

0.087 0.050 0.059 0.073 34,000

4.0 2.3 2.7 3.3 34,000

4.0 2.3 2.7 3.3 34,000

4.0 2.3 2.7 3.3 HOUSE 30 - Min. TWA, mg/m 3 Ratio to EGL : HFC - 23 HFC - 125 HFC - 134a HFC - 143a 74

0.0087 0.0050 0.0059 0.0073 3,300

0.39 0.22 0.26 0.32 3,300

0.39 0.22 0.26 0.32 3,400

0.40 0.23 0.27 0.33  125

C R200b. T he weighted average of the ratios is below 1.0, indicating that this blend is of no concern even if the health hazards are additive.

C HCFC - 22/HCFC - 142b. T he weighted average of the ratios is below 1.0, indicating that this blend is of no concern even if the health hazards are additive.

C HCFC - 22/HFC - 152a/HCFC - 124. T he weighted average of the ratios is below 1.0, indicating that this b lend is of no concern even if the health hazards are additive. Releases from refrigerators and freezers are based on a charge size of 300 g. A conservative estimate of charge sizes for refrigerators and freezers is 240 g for refrigerators and 340 g for f reezers. S ince more people own refrigerators than freezers, the estimated charge size of 300 g used in this anal ys is actually overstates releases and exposures for most of the population.

 Dehumidifiers:

C HCFC - 22;

C HFC - 134a;

C HFC - 152a;

C R200b. The weighted average of the ratios is below 1.0, indicating that this blend is of no concern even if the health hazards are additive.

C HCFC - 22/HCFC - 142b. T he weighted average of the ratios is below 1.0, indicating that this blend is of no concern even i f the health hazards are additive.

C HCFC - 22/HFC - 152a/HCFC - 124. T he weighted average of the ratios is below 1.0, indicating that this blend is of no concern even if the health hazards are additive. Under the assumptions used in this analy sis, all of the other substitute/end use combinations result in exposures above the EGL if the entire charge is released:

 Central air conditioners and home heat pumps : N one of these compounds or blends exceed their EGLs in the house. In the basement, however, all al ternatives (taken either individually or as blends) exceed their EGLs. T hese figures are based on the assumption that about 20 percent of central air conditioners and home heat pumps have a charge size of 3,800 g, about 75 percent have a charge size of 3, 000 g, and 5 percent have a charge size of 700 g.

 Window air conditioners : A ll alternatives exceed their EGLs in the room where the air conditioner is located. A ll window air conditioners are assumed to have a charge size of 1,800 g.  126

As discussed abo ve, these results are based on a comparison of 30 - minute TWA exposures with interim EGL s. Another way to approach this assessment would be to calculate shorter - term exposures and compare them to the cardiotoxic LOAELs or NOAE Ls given in Chapter 3. I f EPA were to calculate 15 minute TWA exposures for the scenarios with 15 - minute releases (i.e., servicing without recycling, 15 - minute accidental release), the TWA exposures would be well below the cardiotoxic NOAELs and LOAELs for every substitute. **6.1.3 Sum**  **mary of Modeling Results** Analy sis has shown that unless the entire refrigerant charge is released over a short period of time, none of the substitutes exceed EPA's threshold of concern for human health risk in any piece of equipment. R outine leakage and servicing with recycling simply will not release enough refrigerant to pose significant short - term or long - term risks to human health. If the entire charge is released, the calculated 30 - minute average concentrations exceed the EGL s for substi tutes in air conditioning equipment. T he following factors should be considered when judging whether these exceedances are cause for concern:

 Recycling at servicing will be required for the HFCs by 1995. Until then, EPA believes that most HFCs will be recycled any way , because of their high cost relative to CFCs.

 Accidental releases of an entire refrigerant charge occur infrequentl y. T he UNEP (1992) reports that less than 5 percent of the refrigerators and freezers have accidental releases of the entire charge.

 The anal ys is is based on conservative assumptions:

C Exposures are generall y calculated for the equipment with the largest charge size.

C All releases are assumed to occur indoors. T his is not necessaril y the case for central air conditi oners, home heat pumps, and window air conditioners.

C It was assumed that people remain in the room in which the release occurs for 30 minutes.

C Air exchange rates estimated are conservative; they reflect an energy efficient house with no windows or do ors open.

C The EGLs that are used as toxicity benchmarks are conservative, and incorporate a margin of safety. Asimilar approach based on cardiotoxic LOAELs or NOAELs would show that exposures are below the concern level. **6.1.4 S**  **afety Concerns: H**  **FC -**  **152a in Household Refrigerators** The release of HFC - 152a in a household kitchen can potentially cause personal injury

in a few ways:

 injury

from sudden overpressure (i.e., shock wave);  127

 injury

from shrapnel resulting from an explosion; and  injury from thermal radiation. The likelihood and severity o f these risks were studied in a report on risk assessment of flammable refrigerants for home appliances. ( EPA 1991). U sing a mathematical model to relate vapor concentration to peak overpressure, the report found that the sudden ignition of a typical charge of HFC - 152a would be sufficient to cause eardrum rupture of a person who was in the kitchen at the time of ignition. T he explosion would also likely cause structural damage to the house. However, the report also found that sudden ignition of a full charge was an extremely unlikel y event; rather, there would be some dispersion of HFC - 152a vapor below the lower flammable limit of 4.4 percent, and thus the subsequent event would be limited to a vapor fire rather than an explosion. Using information on historical leakage rates coupled with a fault tree anal ysis, the report predicts that the probability of a fire or explosion due to an external refrigerant leak is 2.0 x 10 - 8 /y

r (5.0 x 10 - 7 unde r worst - case assumptions). T he probability of an explosion due to leakage of HFC - 152a inside the refrigerator is considerabl y smaller (2.7 x 10 - 13 /y r under average - case assumptions and 7.0 x 10 - 12 /year under worst - case assumptions). **6.2 MOBILE AIR CONDIT**  **IONERS (MACs) 6.2.1**  **Approach Used in a Previous Consumer Exposure Report** The consumer exposure report (Versar 1990) estimated MAC emissions to which consumers could be exposed as the product of four factors: (1) total charge of refrigerant in the sy stem; (2) fraction of refrigerant that leaks from the sy stem before it is noticed and repaired; (3) fraction of refrigerant entering the vehicle passenger compartment; and (4) frequency of leak episodes.

 Total charge : T otal refrigerant charge is based on av erages from a previous study (Chilton 1985) for four vehicle class sizes: subcompact, 27 ozs.; c ompact, 38 ozs.; midsize, 47 ozs.; and large, 53 ozs.

 Total refrigerant leaked before being noticed/repaired : In newer vehicles with protection devices and in warmer climates, the consumer exposure report assumed that leaks would be noticed and fixed quickly . In cooler climates and older cars without protection devices, a MAC leak would probably go unnoticed until most of the refrigerant had leaked. O veral l, the report assumed an average leak of 50 percent of charge capacity.

 Fraction of leak entering passenger compartment : T his parameter depends on the location of the leak (evaporator case or engine compartment) and whether the vehicle is in motion or stationary. T he consumer exposure report assumed that the vehicle is stationary 15 percent of the time that it is in use; that the air conditioning or heat are on 2/3 of the time a vehicle is in operation; and that the average annual consumer vehicle oper ation time is 526 hours.

 Leak episodes per vehicle : T he consumer exposure report assumed that there are 0.76 leaks/y

r/vehicle.  128

Leaks from the evaporator case result in infiltration of the entire release into the passenger compartment, and therefore the highest consumer exposures. T herefore, the remainder of this discussion focuses on evaporator case leaks. T he consumer exposure report's emission calculations for evaporator case leaks are as follows:

Emissions, g/yr=(oz. charge/vehicle class) x ( 0.50 fraction emitted) x (28.35 g/oz) x (0.76 leaks/y

r) Size class Emissions, g/y r Subcompact 290 Compact 409 Midsize 506 Large 602 When a leak occurs in the evaporator case, the rate of air intake affects the concentration of the refrigerant in the passenger compartment b y ei ther circulating the compartment air out of the vehicle (high ventilation rate) or letting the air stand in the compartment (low ventilation rate), allowing refrigerant concentrations to build up. T he consume r exposure report assumed that the MAC is working at maximum level while it is on, minimizing ventilation. T he average speed of travel for a vehicle, according to this report, is 30 mph, yielding a 27 ACH (27 full compartment volumes/hour) ventilation rat e. C oncentrations are then calculated in terms of buildup of refrigerants in the recirculated air. R efrigerant concentrations also depend on passenger compartment sizes, which are broken down into the same four units by a previous study

(Chilton 1985): subcompact vehicles, 2.3 m 3 ; c ompact, 2.5 m 3 ; m idsize, 2.8 m 3 ; and large, 3.1 m 3

. The consumer exposure report's calculated passenger compartment concentrations are as follows:

Concentration, mg/m 3 = (emissions, g/y r) x (1 y r/8760 hrs) x (ventilation rate, 1 hr/27) x (1000 mg/g) x (1/passenger compartment volume, m 3 ) = Size class Concentration, mg/m 3 Subcompact 0.53 Compact 0.69 Midsize 0.76 Large 0.82 Comparing these concentrations to reference concentrations (RfCs) for the substitutes (see Chapter 3) shows that the highest estimated passenger compartment concentration (0.82 mg/m 3 ) is far below all of the RfCs. HCFC - 22 is the only

possible carcinogen of the four substitutes analyzed in the study . I f the consumer exposure r eport's exposure assumptions are used (inhalation rate is 0.6 m 3 /hr for a driving adult; average consumer vehicle operation time is 526 hours per year), the lifetime cancer risk is 2.0 x 10 - 6

. **6.2.2 Comparison of Parameters Contained in Consumer Exposure**  **Report with Data from Other Sources**  Some of the parameters built into the consumer exposure report's MAC analy sis (Versar 1990) are also included in EPA's Vintaging Model and the Market Vision Research Report. Parameters addressed b y both the consumer exposure report and one of these other sources  129

include: (1) total MAC charge; (2) total charge lost before leak is detected and fixed; (3) frequency of operational leak events; and (4) emissions to the vehicle passenger compartment. B elow, the values used i n these other sources are compared to those used by the consumer exposure report.

 Total MAC charge : While the consumer exposure report assumed 53 oz. maximum for total refrigerant charges, the Vintaging Model uses a less conservative 42.3 oz. upper bo und.

 Total charge lost before the leak is detected and fixed : T he Vintaging Model assumes a loss of 30 percent of the initial charge, substantially less than the more conservative average of 50 percent loss of initial charge used by the consumer exposure report.

 Frequency

of operational leak events: According to the consumer exposure report, the frequency

of leak events is 0.76 leaks/car/year. T his value is based on an Automotive Refrigeration Products Institute study in which 384 recharges were pe rformed on 506 air - conditioned vehicles in one year. A ccording to the Vintaging Model, 37 percent of cars with MACs have their MACs serviced in any given ye ar. T hus, the servicing (and therefore, leakage) frequency in the consumer exposure report is about two times higher than the Vintaging Model.

 Total emissions to the passenger compartment : T he Vintaging Model assumes that upper end operating releases from MACs are about 100 grams per ye ar. T his is much lower than the upper end of 602 grams per year assumed by the consumer exposure report. All else being equal, a decrease in the value of any of these parameters would result in reduced risk. A s shown above, the values assigned to these parameters by the other sources are alway s lower than those used by the consumer exposure report. T herefore, an y adjustments that might be made to the consumer exposure anal ys is to be consistent with these other sources would only serve to reduce the already - low exposures and associated health risks. **6.2.3 Summary**  The consumer exposure report estimated consumer exposure to emissions of CFC substitutes from MACs. T hese exposure levels are below those that would raise concern for human health risks. An examination of this report's inputs and assumptions ind icates that the anal ys is is conservative, confirming that consumer exposure is not of concern.  130 **CHAPTER 6 REFERENCES** Automotive Refrigeration Products Institute. 1 988. 1988 Private Sector Vehicle Refrigerant Consumption Study . P ublished by the Automotive Refrigeration Products Institute, Lanham, MD. Chilton. 1 985. Chilton's Guide to Air Conditioning Repair and Service . C hilton Book Co., Radnor, PA. Market Vision Research Report. R esults from survey work performed for the Automotive Ref rigerant Products Institute. U.S. EPA. 1 991. Risk Assessment of Flammable Refrigerants for Use in Home Appliances, Revised Draft Report . G lobal Change Division. S eptember 10, 1991. Versar Inc. 1 990. June 19. Revised Draft Final Report, Consumer Ex posure to Chlorinated Fluorocarbons (CFCs) and CFC Substitutes .**7. G** **ENERAL POPULATION EXPOSURE AND RISK ANALYSIS**

This chapter presents a screening level assessment of the risks to the general population from exposure to ambient air releases of substitutes for CFCs in the refrigeration and air conditioning sectors. E PA previously performed a similar study (EPA 1990a) using data from another report (EPA 1990c). S ince then, more recent data on CFC emissions from refrigeration and air conditio ning equipment have been collected and a new anal ys is conducted. T he evaluation of substitutes has also been expanded to include compounds not previously included in EPA reports. This analy sis assesses each of 20 main end uses in the refrigeration and ai r conditioning sectors. T o develop this list of 20 end uses, the 49 end uses covered b y the Vintaging Model 17 were subdivided into equipment types with similar charge sizes and emission rates. F or each end use, this report examines compounds identified by EPA as possible substitutes for present CFC use. T he list of end uses and substitutes is presented in Attachment 7 - A. The substitutes are grouped into four categories for this analy sis: ( 1) the HCFCs and HFCs; (2) other alternative refrigerants, including ammonia, butane, isobutane, propane, perfluoropropane, cyclopropane, and dimeth ylether; (3) chlorine; and (4) lithium bromide/water absorption and ammonia/water absorption. E ach category is discussed in a separate section below. A lternatives to mech anical refrigeration (e.g., evaporative coolers and turbochillers) are not analyzed, since these alternatives do not use chemical refrigerants and therefore pose no exposure risks to the general population. The four anal ys es below are presented as screeni ng anal ys es. T heir purpose is to identify the proposed substitutes for all end uses that may pose any potential concern for human health or environmental risk. A s a result, the analy ses employ conservative assumptions that tend to overestimate potential risk. C onsiderable uncertainty exists in these analy ses. T he reader should recognize the caveats and limitations identified throughout the chapter. **7.1 HCFCs AND HFCs**  **7.1.1 Approach**  This analy sis of the HCFCs and HFCs uses conservative screening assumptions to estimate potential risks. T he basic approach is to: ( 1) estimate high - end annual releases of substitutes from equipment manufacturing plants, operating sites, service stations, and recycling centers or salvage yards; (2) use generic disper sion factors to calculate concentrations of the substitutes in air near the release site; and (3) compare these concentrations to health - based reference concentrations (RfCs) and, for carcinogens, calculate cancer risk. T hese three steps are discussed in more detail below.

17 A complete description of the Vintaging Model and the other methods used to estimate refrigerant emissions by equipment type can be found in Chapter 4.A. Estimating Ambient Air Releases

To estimate releases to ambient air, the first step was to identify the activities that lead to emissions and the ty

pes of sites at which such activities occur. A ctivities through which CFC substitut es are released to the environment include equipment manufacture, installation, operation, servicing, and disposal. T he ty pes of sites at which these activities occur include factories, operating sites, service stations, and recycling centers or salvage yards. The second step was to calculate the amount of CFC substitute released during each activity . F or the screening - level anal ys is, it was assumed that in all cases the amount of substitute released would equal the amount of CFC released presently . M ost CFC release information was derived from input files to the Vintaging Model; some data were received directly from industry associations and individual manufacturers. The emissions values used in the exposure assessment for each end use represe nt the highest values that would be expected to occur as a result of typical refrigeration practices. Release estimates for each of the 20 end uses were based on the equipment ty pe with the highest emission rate within that end use (generall y the equipment with the largest charge size). Catastrophic scenarios, such as a factory explosion that could cause temporarily high exposures in a nearb y town, were excluded. 18 Emissions during servicing and disposal are subject to recycling, which can greatl y decreas e the amount of refrigerant released to ambient air. Under Section 608 of the Clean Air Act, the recycling of HCFCs became mandatory in 1992. H owever, HFC recycling will not be required until 1995. T herefore, scenarios both with and without recycling we re examined for HFCs, but only

scenarios with recycling for HCFCs. The third step in estimating releases involved using the information generated in the first two steps to calculate the amount of CFC substitute released to the atmosphere, in a ye ar's time , from each ty

pe of release site. T he methods used to calculate these releases are summarized below.

18 Events of this nature are addressed by the Emergency Preparedness and Community Right - to - Know Ac t of 1986 (EPCRA), also known as Title 3 of the Superfund Amendments and Reauthorization Act (SARA) of 1986. Under Sections 311 and 312, Material Safety Data Sheets (MSDSs), which provide chemical data or lists of chemicals, must be provided to local plan ning committees and emergency personnel to assist their decisionmaking and preparedness in the event of a emergency. Regulated chemicals include those posing a physical hazard (e.g., flammability, combustibility, reactivity, corrosivity, oxidizing potenti al, and pressurized gases) or those posing a health hazard (e.g., carcinogens, toxins, and irritants).  133

 Releases from factories : Annual air releases of HCFCs and HFCs from factories were calculated b y multiplying the number of units manufactured per fact ory per ye ar by the amount of substitute released per unit at the factory. O ne end use, low pressure centrifugal chillers, was an exception. O n the recommendation of a leading manufacturer, it was assumed that onl y 20 percent of the units were tested (an d therefore charged and recovered) at the factory . D ata derived from the Vintaging Model, and originall y from comprehensive industry surveys, were used to estimate the total number of pieces of equipment manufactured per ye ar in the U.S. In calculating the number of units manufactured per plant per year, unequal market share was assumed (i.e., that some manufacturers are larger and produce more units per year). M ore accurate data were used if verifiable information was readil y accessible. M anufacturing emissions include emissions associated with equipment and component testing. Where applicable, charging and leak testing emissions were also included.

 Releases from equipment operating sites : T o estimate air releases from operating sites, the highest possible amount of CFC substitute that could be released from an operating site in an y given year was calculated, which would be either the year of installation or disposal. T o do this, the releases from equipment operation, servicing, and either installation or disposal were added together, depending upon which of the latter two activities' releases was higher. ( "Disposal" releases occur at the equipment operating site if the charge is drained or removed at the site before the equipment is dismantled, wh ich has been assumed in all cases except for automobile air conditioners (MACs) and household appliances.)

 Releases from service stations : T his release site applied only to the MACs end use. T wo t ypes of activities that cause emissions ty picall y occur at service stations: the installation of after - market MACs and the servicing of MACs. Annual air releases associated with each activity w ere calculated by

multiplyingthe number of MACs installed and serviced annuall y at service stations by the amount of substitute released during each installation or servicing. S ince Section 609 of the CAA mandates the recycling of refrigerants during the servicing of MACs, emission estimates for servicing assumed that recycling would occur. T h e annual installation and servicing releases were added together to derive the total annual releases from the service station.

 Releases from recycling centers/salvage yards releases : Acentralized equipment disposal scenario was created for each of two ty pes of end uses C household appliances and MACs:

C The disposal scenario for household appliances was based on an actual site

C an Appliances Recycling Centers of America (ARCA) facility in Minneapolis, Minnesota C which processes refrigerators, freeze rs, room air conditioners, and dehumidifiers. R eleases were calculated b y multiplying disposal emissions by

the number of appliances processed annually at that site.

C The disposal scenario for MACs is a large automobile salvage yard. Releases were esti mated by multiplying disposal emissions by the number of cars processed annually that contain MACs which still possess their  134 charge. Information on these parameters was obtained from a New Jersey Department of Environmental Protection study (Aucott 1990). Attachment 7 - B details all of the assumptions used for estimating ambient air releases for each end use. B. Estimating Downwind Concentrations Downwind concentrations were estimated using the Industrial Source Complex Lo ng Term (I SCLT) Dispersion Model , provided b y Versar, an Agency contractor, and summarized in Attachment 7 - C. T his approach consisted of converting the release estimates from kilograms per ye ar to grams per second, and then multiplying by normalized dispersion factors (in μ g/m 3 per g/se c). T hese calculations yielded fence - line concentrations in μ g/m 3

. P rofessional judgment was used to determine which factors to appl y to each t ype of site. C. Screening Potential Risks To estimate potential risk, exposure information was merged with available toxicity data, as follows:

 To evaluate noncarcinogenic effects, the modeled exposure concentrations were compared to reference concentrations (RfCs).

 To calculate cancer risks, EPA's standard risk equation was used. Alifetime average daily

d ose of the substitute was estimated using an exposure concentration, an average 20 m 3 /day

inhalation rate, and an average body weight of 70 kg. F or factory releases, the calculated cancer risks were adjusted to account for the phaseout of H CFCs. H CFC - 22 (a long - lived HCFC) will be phased out of new equipment production by 2010; therefore, a person living downwind of a factory producing equipment using HCFC - 22 would be exposed to the substitute for only 18 ye ars (1992 to 2010), instead of th e full 70 years which the cancer risk equations assume. T hus, a correction factor of 18/70 was used to calculate cancer risks for HCFC - 22 from factories. S imilarly , for HCFC - 123, a short - lived HCFC scheduled to be out of production by 2015, a correction factor of 23/70 was applied to the calculated cancer risks. T he reader should note that the projected dates for these accelerated phaseouts are tentative and subject to change. The reference concentrations and cancer potency factors used in this assessme nt are given in Chapter 3 of this document. **7.1.2 Results**  All end uses have calculated exposure concentrations well below the reference concentrations for each HCFC and HFC substitute. E stimated cancer risks from HCFC - 22 and HCFC - 123 were highest during factory releases, but still below 1E - 05, and are therefore not considered to be of concern. E xhibit 7 - 1 summarizes the results, showing the highest exposure concentration for each substitute and the end use responsible. C omplete results for each end use and potential substitute can be found in Attachment 7 - D.  135

**7.1.3 Caveats and Limitations**  This screening anal ys is of risks to the general population is a simple screening anal ys is that incorporates a variety

of simplifying assumptions. T he approach was intended to be conservative, i.e., to overestimate exposure point concentrations and potential human health risks. The major caveats and limitations of the analy sis are listed below. A. Estimating Releases . It was necessary to make assumptions to characte rize releases, and the assumptions that would lead to the most conservative risk estimates were generall y chosen.

C Within each end use grouping, there may have been several types of equipment with slightly

varying charge sizes. It was assumed that the charge size of all equipment was equal to the largest charge of a piece of equipment in that category. In about half of the end uses, this assumption is true, but for the other half this is a very c onservative assumption. F or example, only 10 percent of commercial direct air conditioning equipment has the assumed charge size of 33 kg. T he other 90 percent has a charge of only 10.2 kg, and so the charge size (and thus releases) for 90 percent of commercial direct air conditioning equipment has  136

**EXHIBIT 7 -**  **1 RESULTS SUMMARY FOR HCFCs AND HFCs**  **19 Substitute**  **Highest Exposure**

**Concentration/ RfC Ratio**  **a Highest** 

**Cancer Risk**  **Associated End Use/Site** HCFC - 22 9.7 E - 03 7.1 E - 06 Central A/C and Home Heat Pumps/Factory HCFC - 123 1.0 E - 02 4.3 E - 06 High Pressure Centrifugal Chillers/Factory HCFC - 124 1.1 E - 03 N/A Retail Food Stand Alone/Factory HCFC - 141 b 2.1 E - 04 N/A Low Pressure Centrifugal Chillers/Factory HCFC - 142 b 3.2 E - 03 N/A Refrigerators and Freezers/Factory HFC - 23 8.1 E - 02 N/A Central A/C and Home Heat Pumps/Factory HFC - 125 4.9 E - 02 N/A Central A/C and Home Heat Pumps/Factory HFC - 134 1.0 E - 02 N/A High Pressure Centrifugal Chillers/Factory HFC - 134a 4.9 E - 02 N/A Central A/C and Home Heat Pumps/Factory HFC - 143 1.4 E - 03 N/A High Pressure Centrifugal Chillers/Factory HFC - 143a 6.9 E - 03 N/A Central A/C and Home Heat Pumps/Factory HFC - 152a 9.5 E - 03 N/A Window A/C Units/Salvage Yard HFC - 227ea 1.1 E - 02 N/A Refrigerators and Freezers/Factory N/A = N ot Applicable

a Some of the RfCs are Agency - verified while others are not. S ee Exhibit 3 - 1 for further information.

19 **Results are**  **based on**  **very conservative,**  **screening -**  **level assumptions**  **and are**  **not indicative**  **of typical operating practices.**  **S ee text and attachm**  **ents for more detail.**  137 been overestimated. S ee Attachment 7 - E for a table detailing the charge sizes for the actual equipment versus the assumed charge size for each end use.

C The number o f units manufactured per factory is not tracked by

the Vintaging Model, so estimates for this analy sis had to be developed. D ata for production rates were based on estimated market shares for the largest manufacturer. F or example, if there are three manu facturers of chillers, it was assumed, based on information from these manufacturers, that the largest manufacturer has 50 percent of the market share and of total annual production. It was also assumed that this manufacturer's total annual production was manufactured at one factory . T hese assumptions will, in many cases, result in an overestimation of the true production (and thus releases) at the actual largest factory .

C With one exception (low pressure chillers), it was assumed that every piece of equipment is charged (and recovered) at least once in the factory for run testing, although some manufacturers' quality control may include testing only a portion of all equipment sold.

C It was assumed that the equipment contains its full original charge at the point of service. In practice, this would rarel y be the case since most servicing calls are made after leaking of refrigerant causes the equipment to malfunction. T he effect of this assumption is to overstate releases, since the amount released is a percentage of the charge at the time of servicing.

C Disposal emissions also assume that a percentage of the total charge is vented at disposal, although this is rarel y the case. A s in servicing, a portion of the charge will have leaked before disposa l.

C Reports from manufacturers of certain ty pes of equipment, such as chillers, indicate that refrigerant leakage from operating equipment varies significantl y depending on whether the equipment's level of maintenance is poor, average, or above average. Poor maintenance was assumed in all cases. An example of the amount of overestimation of releases which this approach could yield can be seen in chillers, of which onl y five percent to ten percent are generally poorl y maintained.

C The amount of substitute used may not equal the amount of CFC used, due to the use of blends, increased efficiency i n newl y - built equipment, and the increased cost of the substitutes and the concomitant smaller equipment charge sizes. A lso, some substitutes, such as HCFC - 123, are already in use today and are known to be handled very differentl y f rom CFCs (i.e., they are handled more carefull y). In the case of HCFC - 123, a possible carcinogen, the actual risks will be smaller than those predicted. B. Estimating Downwind Concentrations . Uncertainties associated with derivation of the dispersion factors are discussed b y EPA (EPA 1990b). T hey include the following:

C EPA used a generic site location to model downwind concentrations. T he meteorological conditions at this generi c site were selected to cause conservative estimates of downwind concentrations.  138

C EPA's selection of model parameters characterizing the release (e.g., release height, size of the release facility) were based on professional judgment.

C Facilit y fenceline distance estimates (where exposure was simulated to occur) were also assumed b y EPA. F or some t ypes of release sites, the model could not estimate concentrations at the assumed fenceline distance because in some cases the distances were as clos e as 10 meters. In these cases, the modeled concentrations at the exposure point were based on the highest concentrations predicted, but could be underestimates.

C The uncertainty f

aced in selecting dispersion factors to apply t o each ty

pe of release sit e is discussed in detail in Attachment 7 - C. C. Screening Potential Risks . T here are three important caveats associated with the risk calculations:

C Most of the calculations assume that an exposed individual lives and works in the same zone of concentration 24 hours per day , year - round, throughout a 70 - ye ar lifetime. A lthough this conservative assumption is often used in risk assessments, it is overly

conservative for the HCFCs, which are scheduled to be phased out of production. T o account for the pha seout in HCFC production, it was assumed that equipment manufacturing facilities would stop placing HCFC - 22 and HCFC - 123 in equipment by 2010 and 2015, respectivel y. T herefore, when calculating cancer risk, the duration of exposure to factory releases of these substitutes was shortened to 18 and 23 years, respectively. Asimilar adjustment was not made in exposures to operating site releases because the phaseout will not preclude HCFCs from being used in existing equipment for the length of the equipment' s lifetime. H owever, because the equipment is likely to replaced before 2062 C the end of the exposed individual's 70 - ye ar lifetime C cancer risks from releases of HCFC - 22 and HCFC - 123 from operating sites are overestimated in this analy sis.

C Risks from exposure to operating site releases were based on the highest amount of substitute that would be released in an y one ye ar (i.e., the sum of releases from equipment operation, servicing, and either installation or disposal). B ecause installation and dispo sal each happen onl y once over the equipment's lifetime, and servicing ty

picall y occurs less frequentl y than once a ye ar, exposures and risks from operating sites are overestimated. **7.1.4 Conclusions**  Even employing conservative screening assumptions, EPA found that there are no end uses within the refrigeration or air conditioning sectors where the use of HFCs or HCFCs as substitutes for CFCs will result in exposure concentrations above the chemicals' health - based reference concentrations for non - cancer e ffects. S imilarly , there are no areas for which predicted cancer risks would be above the upper - bound cancer risk level of concern, 10 - 5

.  139

**7.2 OTHER ALTERNATIVE REFRIGERANTS**  This section discusses the following refrigerant substitutes: ammonia, butane, isobutane, propane, cyclopropane, perfluoropropane, and dimethyl ether (DME) 20

. A fter a background discussion, the approach for the analy sis and the results are discussed. **7.2.1 Background**  Many of these alternative refrigerants currentl y find wide use in industrial applications. Ammonia was one of the first refrigerants to gain acceptance, and is used almost exclusively i n the meat packing, dairy , frozen juice, brewery , cold storage, and other food industries. T he hydrocarbon refrigerants are used primaril y in oil refineries and chemical plants, where they are frequentl y available as part of the process stream. T he expanded use of many of the refrigerants in this section in other refrigeration and air conditioning equipment has been proposed, particularly

as components in blends with the HFCs and HCFCs.

20 Several of these refrigerant substitutes are used in blends while others may be used in their pure form.  140

Most industrial process refrigeration sy stems are designed by consulting firms that specialize in the field. T he consultants ty pically work with the client to determine the exact specifications (cooling loads, for example), then design the sy stem using off - the - shelf or speciall y fabricated components. S maller, more standard designs, such as those for a cold storage warehouse, are more likely to use off

- the - shelf components as these are cheaper and more readil y available. T he consultants sometimes supervise construction, installation, and start - up of the refrigeration s ys tem. Compressors for large industrial process refrigeration sy stems are built by a handful of companies. B ecause they are large, complicated pieces of machinery , compressors are tested at the factory , but for safet y purposes testing is not done with the refrigerant that will ultimately be used. F or h ydrocarbon refrigerants, run testing is ty picall y done with dry air, and a cor relation made with the refrigerant to determine the compressor's operating performance (Shephard 1992). Ammonia compressors are tested with air and a soap solution or tested under water to see if bubbles appear at joints. Ammonia package s ys tems (those that have the evaporating and condensing units attached) are similarl y tested with an air/soap solution, then charged with dry nitrogen before being shipped (Anderson 1992; Pillis 1992). Industrial s ys tems are erected in the field, leak tested again, then charged with the refrigerant. C are is taken during the charging operation to ensure that vapor concentrations are kept below hazardous levels. Ammonia sy stems usually have a charge size that makes them subject to OSHA PELlimits for ammonia (Anderson 199 2), while ASHRAE standards for refrigeration s ys tems recognize that worker exposure due to routine operating leakage from the sy stem, or that occurs during servicing, should be kept below threshold levels. T hese codes are adopted into local and state buil ding codes in most of the U.S. and are used as guidelines b y the sy stem designers 21

. In all cases, it is unlikely that emissions from a process refrigeration sy stem operating on an industrial refrigerant would exceed those of a similar sy stem operating on CFCs or HCFCs. **7.2.2 Approach**  This analy sis of ammonia, butane, isobutane, propane, cyclopropane, perfluoropropane, and DME is a simple screening anal ys is to determine whether general population exposure is potentially

of concern in specific end uses. The analy sis used the fenceline exposure concentrations predicted above for HCFCs and HFCs and assumed that the fenceline concentrations of the alternative refrigerants noted above would be the same. T his is a conservative approach because (1) the HCFC an d HFC fenceline concentrations were calculated using conservative assumptions that are likel y to overestimate exposure levels, and (2) releases of these alternative refrigerants are likel y to be even lower because of the OSHA and ASHRAE standards to which their refrigerant uses are subject. Conclusive data on the significance of factory releases were unavailable. C onsequently , to be conservative in the anal ys is for these alternative refrigerants, factory releases were evaluated in addition to releases on - site during operation and servicing and those at disposal. T he only exception to this approach was for ammonia. A lthough compressors for large industrial process refrigeration s ys tems are tested at the factory , for safet y purposes this testing is not don e with

21 ASHRAE code 34 - 1992 classifies ammonia as a toxic and mildly flammable refrigerant and the hydrocarbons as highly flammable refrigerants.  1 41

ammonia. S imilarly , charging of ammonia s ys tems is ty pically performed at the operating site rather than the factory . T herefore, ammonia is unlikely to be released from a factory setting. These fenceline concentrations were then compared to reference concentrations for each of the substitutes. F rom Chapter 3, the following reference concentrations were employed 22 :

22 Some of the RfCs are Agency- verified while others are not. S ee Exhibit 3 - 1 for further information.  142

Ammonia: 0.1 mg/m 3 Perfluoroprop ane: 4.5 mg/m 3 Butane: 0.95 mg/m 3 Cyclop ropane: 0.9 mg/m 3 Isobutane: 0.95 mg/m 3 Dimethyl ether: 0.4 mg/m 3 Propane: 0.9 mg/m 3 **7.2.3 Results**  Exhibit 7 - 2 summarizes the results of the approach described in 7.2.2. F or each end use, the highest exposure concentration (from Attachment 7 - D) is shown. T he location of this exposure (i. e., at the factory , on - site, or at the disposal site) is also reported. F or the applicable refrigerants, the ratio of the concentration to the substitutes' reference concentrations is calculated. None of these ratios exceeded the health - based thresholds. Caveats and limitations associated with this analy sis are the same as those discussed above for HCFCs and HFCs. I n addition, there is considerable uncertainty associated with the health - based thresholds used for butane, propane, and perfluoropropane, which were extrapolated from workplace exposure limits rather than calculated from laboratory s tudies. E PA believes that the exposure limits used in this analy sis are conservative. Given the conservative nature of the release estimates and interim health - based levels used in this anal ys is, EPA concludes that general population exposure is not of concern for these seven substitutes. **7.3 CHLORINE**  Chlorine has been proposed as a Class I substitute refrigerant for use in chlorine liquification, a processing step in the manufacture of the chemical. When chilled below its boiling point, chlorine can be stored as a liquid at atmospheric pressure, a method that for safety reasons is much preferred to storing the chemical as a pressurized gas at ambient temperat ures. Compatibility

o f the refrigerant with liquid chlorine is critical because of chlorine's high reactivity ; CFC - 12 is widely

used because it is nonreactive.  143 **EXHIBIT 7 -**  **2: R** **ESULTS SUMMARY FOR OTHER ALTERNATIVE REFRIGERANTS a** 

a Releases are based on the assumption that the refrigerant is not recycled when the equipment is serviced or dismantled for di sposal. T his does not reflect common operating practices and therefore overstates true risk.  144

Chlorine refrigeration sy stems generall y d o not exchange chlorine with the process stream. However, the sy stem would be placed so that any l eakage or losses of chlorine would be contained and neutralized b y the process safety mechani sms. C harge sizes in the refrigeration s ys tem would probabl y be less than 1000 kg, as compared to a bulk storage container havingseveral hundred times that capacity . C hlorine emissions from the refrigeration sy stem are likel y to be dwarfed b y those emanating from the process and storage s ys tems, which are already kept small for reasons of worker safety . Based on these considerations, EPA does not believe that the use of chlorine as a refrigerant in this limited application C the manufacture of chlorine C poses significant incremental risk to the general population. **7.4 LITHIUM BROMIDE AND AMMONIA IN ABSORPTION SYSTEMS**  Lithium bromide is used in commercial absorption sy stems, where it serves as an absorbent. S uch s ys tems operate at very low pressure to allow water to act as a refrigerant. T he lithium bromide is in the form of an ionic salt having a negligible vapor pressure, so there is no possibility

of a gaseous release in other than catastrophic circumstances. L ithium is also a relativel y nontoxic, nonflammable, nonexplosive, chemicall y stable chemical, and poses little incremental risk to the general population. Absorption refrigeration sy stems employing a mixture of ammonia and water have been used for man y ye ars. S mall refrigeration units are po pular in recreational vehicles and hotel refrigerators as they

need no electrically - driven mechanical pump. D omestic absorption ty pe sy stems use hydrogen to maintain a sy stem pressure high enough to allow the ammonia refrigerant to evaporate at low pressure and temperature (and condense at room temperature), and are ruggedly constructed; the absorption mechanism itself is a sealed unit, which usually needs no servicing over its operating life. C ommercial ammonia absorption sy stems are used for air condit ioning comfort cooling, particularl y in instances where waste heat is available. T hese produce chilled water, which is circulated to the space being cooled. T he same standards and guidelines that appl y to ammonia vapor compression equipment also apply to commercial ammonia absorption systems. In a well - maintained sy stem, it is unlikely that ammonia emissions would pose a problem.  145 **CHAPTER 7 REFERENCES** Anderson, Kent. 1 992. M ay 5. Phone conversation between Mark Radka, I CF Incorporated, and Kent Anderson, Chairman of the International Institute of Ammonia Refrigeration. Aucott, Michael. 1 990. D ecember 14. Feasibility of CFC - 12 Reclamation from Salvaged Vehicles . D epartment of Environmental Protection, Division of Solid Waste Management, State of New Jersey . Pillis, J. 1 992. M ay

5. P hone conversation between Mark Radka, ICF Incorporated, and J. Pillis, Chief Engineer, The Frick Company. Shephard, James. 1 992. M ay 4. P hone conversation between Mark Radka, I CF Incorporated, and James Shephard, Vice President of Engineering, Lewis Energy S ys tems, and Chair of the ASHRAE Technical Committee on Custom Refrigeration Sy stems. U.S. EPA. 1 992. Regulatory Impact Analysis: C ompliance with Section 604 of the Clean Air Actfor the Phaseout o

f Ozone Depleting Chemicals . O ffice of Air and Radiation. M arch 12, 1992. U.S. EPA. 1 990a. External Review Draft, Hydrofluorocarbons and Hydrochlorofluorocarbons, Interim Report . O ffice of Toxic Substances. N ovember, 1990. U.S. EPA. 1 990b. Potential Ambient Inhalation Exposures for Chlorofluorocarbon Substitutes .

Office of Toxic Substances. E xposure Evaluation Division, Exposure Assessment Branch. N ovember 7, 1990. U.S. EPA. 1 990c. Revised Draft: Occupational Exposure and Environmental Rele ase Data for Chlorofluorocarbons (CFCs) and Their Substitutes . O ffice of Toxic Substances.**ATTACHMENT 7 -**  **A DETAILED CATEGORIZATION OF REFRIGERATION END USES** 

**AND EQUIPMENT TYPES ("Near**  **- Term" Substitutes In Italics)**  1. Retail Food - Parallel Sy stems

 CFC - 12 (medium temperature) HFC - 134a HCFC - 22 HCFC - 22/HFC - 152a/HCFC

- 124 HFC - 125/HFC

- 143a/HFC

- 134a ammonia

 CFC - 502 (low temperature) HFC - 125 HFC - 143a HCFC - 22 HCFC - 22/propane/perfluoropropane HCFC - 22/propane/HFC

- 125

 HCFC - 22 (medium and low temperature) HFC - 125 HFC - 134a HFC - 23/HFC - 134a HFC - 125/HFC

- 143a HCFC - 22/propane/HFC

- 125 2. Retail Food - Stand Alone Sy stems

 CFC - 12 (medium temperature) HFC - 134a HCFC - 22 HCFC - 22/HFC - 152a/HCFC

- 124 HFC - 125/HFC

- 143a/HFC

- 134a ammonia

 CFC - 502 (low temperature) HFC - 125 HFC - 143a HCFC - 22 HCFC - 22/propane/perfluoropropane HCFC - 22/propane/HFC

- 125 3. Cold Storage Warehouses

 CFC - 12 (medium/high temperature) HFC - 134a HFC - 152a HCFC - 22 HCFC - 22/HFC - 152a/HCFC

- 124 ammoniaturbochill

 HCFC - 22 (medium/high temperature) HFC - 134a HFC - 152a HFC - 23/HFC - 134a HCFC - 22/HFC - 152a/HCFC

- 124 ammonia turbochill

 CFC - 502 (low temperature) HFC - 125 HCFC - 22 HCFC - 22/propane/perfluoropropane ammonia 4. Reciprocating Chillers a

 CFC - 12 HFC - 134a HFC - 152a HCFC - 22 HCFC - 123 HFC - 125/HFC

- 143a/HFC

- 134a

 HCFC - 22 HFC - 134a HFC - 23/HFC - 134a HFC - 125/HFC

- 143a HCFC - 22/propane/HFC

- 125 ammonia 5. Screw Chillers a

 HCFC - 22 HFC - 134a HFC - 23/HFC - 134a HCFC - 22/propane/HFC

- 125 ammonia 6. Centrifugal Low Pressure Chillers a

 CFC - 11 HFC - 134a HCFC - 22 HCFC - 123 HCFC - 141b

a Includes three maintenance profiles: p oor, average, above average. 

  148 lithium bromide/water absorption ammonia/water absorption 

  149

7. Centrifugal High Pressure Chillers a

 CFC - 12 HFC - 134a HCFC - 22 HCFC - 123 lithium bromide/water absorption

 CFC - 114 HCFC - 124 HCFC - 142b R200b R200c R200d R200e R200f R200g R200i R200j

 CFC - 500 HFC - 134a HCFC - 22/HFC - 152a/HCFC

- 124 HFC - 134a/HFC

- 152a ammonia

 HCFC - 22 HFC - 134a ammonia 8. Industrial Process Refrigeration - Low Pressure Sy stems

 Centrifugal Package Sy stems (CFC - 11) HCFC - 123 HCFC - 141b

 Centrifugal Built - Up S ys tems (CFC - 11) HCFC - 123 HCFC - 141b 

  150

9. Industrial Process Refrigeration - High Pressure Package Sy stems

 CFC - 12 Reciprocating HFC - 134a HFC - 143a  HCFC - 22 Reciprocating HFC - 152a HCFC - 22  CFC - 502 Reciprocating a HFC - 23/HFC - 134a HFC - 125/HFC

- 143a HCFC - 22/HFC - 152a/HCFC

- 124 HFC - 125/HFC

- 143a/HFC

- 134a HCFC - 22/propane/HFC

- 125 propane butane ammonia 10. Industrial Process Refrigeration - High Pressure Built - Up Systems

a This end use includes extra large ice make rs. 

  151

 CFC - 12 Reciprocating HFC - 134a HFC - 152a  HCFC - 22 Centrifugal HCFC - 22 HFC - 23/HFC - 134a  CFC - 500 Centrifugal HFC - 125/HFC

- 143a HCFC - 22/HFC - 152a/HCFC

- 124  CFC - 12 Reciprocating HFC - 125/HFC

- 143a/HFC

- 134a HCFC - 22/propane/HFC

- 125  HCFC - 22 Reciprocating propane butane ammonia chlorine 11. Ice Skating Rinks

 CFC - 12 HFC - 134a HFC - 152a  HCFC - 22 HCFC - 22 HFC - 23/HFC - 134a  CFC - 502 HCFC - 22/HFC - 152a/HCFC

- 124 ammonia 12. Medium Ice Makers

 CFC - 12 HCFC - 22 HFC - 134a HFC - 152a HCFC - 22/HFC - 152a/HCFC

- 124 ammonia 13. Large Ice Makers

 CFC - 12 HCFC - 22 HFC - 134a HFC - 152a HCFC - 22/HFC - 152a/HCFC

- 124 ammonia 14. Refrigerated Transport Units

 CFC - 12 HFC - 134a HCFC - 22 HCFC - 22/HFC - 152a/HCFC

- 124 HFC - 125/HFC

- 143a/HFC

- 134a 

  152

 CFC - 500 HFC - 134a HCFC - 22 HCFC - 22/HFC - 152a/HCFC

- 124 HCFC - 22/propane/HFC

- 125

 CFC - 502 HFC - 125 HFC - 134a HCFC - 22 HCFC - 22/propane/HFC

- 125 15. Window Air Conditioners

 HCFC - 22 HFC - 125 HFC - 134a HFC - 23/HFC - 134a HFC - 125/HFC

- 143a 16. Central Air Conditioners and Home Heat Pumps

 Package Terminal Air HFC - 125 Conditioners (HCFC - 22) HFC - 134a HFC - 23/HFC - 134a  Residential Unitary

Air HFC - 125/HFC

- 143a Conditioners (HCFC - 22) HFC - 125/HFC

- 143a/HFC

- 134a HCFC - 22/propane/HFC

- 125  Unitary

Heat Pumps (HCFC - 22)

 Water Source Heat Pumps (HCFC - 22) 

  153

17. Commercial Direct Expansion Air Conditioning Sy stems

 Small Commercial Air HFC - 125 Conditioners (HCFC - 22) HFC - 134a HFC - 23/HFC - 134a  Large Commercial Air HFC - 125/HFC

- 143a Conditioners (HCFC - 22) 18. Refrigerators and Freezers

 Refrigerators (CFC - 12) HFC - 134a HFC - 152a  Freezers (CFC - 12) HCFC - 22 R200b HCFC - 22/HFC - 152a/HCFC

- 124 HCFC - 22/HCFC

- 142b ammonia/water absorption 19. Other Refrigerated Appliances

 Dehumidifiers (CFC - 12) HFC - 134a HFC - 152a  Vending Machines (CFC - 12) HCFC - 22/HFC - 152a/HCFC

- 124

 Small I ce Makers (CFC - 12) HCFC - 22

 Water Coolers (CFC - 12)

 Small I ce Makers (CFC - 502) HCFC - 22 20. Mobile Air Conditioners

 CFC - 12 HFC - 134a HCFC - 22/HFC - 152a/HCFC

- 124**ATTACHMENT 7 -**  **B: ASSUMPTIONS FOR AMBIENT AIR RELEASE CALCULATIONS**  **a**

RETAIL FOOD SYSTEMS Ty pe/Site of Release Parallel Sy stems Stand - Alone Sy stems MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 2,900 30,000 b Release per unit manufactured (kg) 6.0 2.0 ON - SI TE RELEASES No. of units per site 1 2 Release per unit installed (kg) 93 3.0 Release per unit serviced (kg) without recycling 7.7 20 with recycling 3.1 1.2 recycling efficiency 99% 99% Release per unit operating (kg/yr) 130 1.9 Release per unit disposed (kg) without recycling 470 19 with recycling 4.7 0.19 recycling efficiency 99% 99%

a Data from ICF's Vintaging Model and supplemental analysis performed by ICF. b The largest manufacturer of retail food refrigeration equipment (Hussman) manufactures approximately 30,000 units per year in one factory.    155 COLD STORAGE WAREHOUSES Ty pe/Site of Release Cold Storage Warehouses MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 57 a Release per unit manufactured (kg) 15 ON - SI TE RELEASES No. of units per site 4 b Release per unit installed (kg) 3.5 Release per unit serviced (kg) without recycling 52 with recycling 5.0 recycling efficiency 99% Release per unit operating (kg/yr) 50 Release per unit disposed (kg) without recycling 250 with recycling 2.5 recycling efficiency 99%

a Based on approxi mately 43,140,000 cubic feet of new cold storage warehouse space per year, an average warehouse volume of 1,000,000 cubic feet, and an estimated four refrigeration units per warehouse, 173 units of equipment are produced per year. One manufacturer estimat es that there are 15 manufacturers of cold storage refrigeration equipment, and another reports that there are three. We assume that there are three manufacturers, each producing 57 units per year. b Assumes that a typical warehouse has 1,000,000 cub ic feet of refrigerated space, requiring a total size of 1000 kg that is provided by four units (250 kg each).    156 CHILLERS Ty pe/Site of Release Recipro cating Chillers Screw

Chillers Centrifugal Chillers

Low Pressur e High Pressure MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 3,000 a 230 b 1,200 c 370 c Release per unit manufactured (kg) 5.0 5.1 16 d 52 ON - SI TE RELEASES No. of units per site 1 1 1 1 Release per unit installed (kg) 1.1 1.1 2.0 2.0 Release per unit serviced (kg) without recycling 5.1 e 11 e 28 e 37 e with recycling 0.15 0.21 1.3 1.4 recycling efficiency 99% 99% 99% 99% Release per unit operating (kg/yr) 23 f 54 f 110 f 260 f Release per unit disposed (kg) without recycling 73 230 450 900 with recycling 0.73 2.3 4.5 9.0 recycling efficiency 99% 99% 99% 99%

a This estimate is based on three chiller manufacturers (Trane, York, Carrier) producing 90 percent of new chillers in approximately equal p roportion. b Assumes that all screw chillers are manufactured at the same factory. c Assumes that three manufacturers (Trane, York, Carrier) produce nearly all chillers, and that one manufacturer has 50 percent of the market share. d According to Trane, only 20% or less of the units manufactured are charged at the factory. e The more frequently a chiller is serviced, the greater its servicing related emissions will be. Above average maintenance is assumed for the purpose of estimating servicing releases. f Reports from chiller manufacturers indicate that refrigerant leakage from operating equipment varies significantly depending on whether the chiller's level of maintenance is poor, average, or above average. P oor maintenance is assumed for the purpose of estimating operating releases.    157 IN DUSTRIAL PROCESS REFRI GERATION Ty pe/Site of Release Low Pressure High

Pressure Package High

Pressure Built Up Ice

Skating Rinks Medium

Ice Makers Large Ice

Makers MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 32 a 130 a 130 a 41 a 50,000 b 8.0 c Release per unit manufactured (kg) 24 13 190 1.0 0.19 2.1 ON - SI TE RELEASES No. of units per site 1 1 1 1 1 1 Release per unit installed (kg) 11 11 11 11 0 0.68 Release per unit serviced (kg) without recycling 140 19 910 28 2.3 34 with recycling 15 2.8 10 1.3 0.05 0.68 recycling efficiency 99% 99% 99% 99% 99% 99% Release per unit operating (kg/yr) 68 27 1,800 57 0.15 2.2 Release per unit disposed (kg) without recycling 680 180 9,100 1,400 2.3 34 with recycling 6.8 1.8 91 14 0.02 0.34 recycling efficiency 99% 99% 99% 99% 99% 99%

a Assumes that three manufacturers (Trane, York, Carrier) produce nearly all of the equipment in this table (excluding ice makers) and that one manufacturer has 50 percent of the market share. b There are ten manufacturers of medium size ice makers. A ssumes that the largest manufacturer has one third of total annual p roduction. c Assumes a single manufacturer of large ice makers.    158 TRANSPORT REFRI GERATION Ty pe/Site of Release Transport Refrigeration MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 14,100 a Release per unit manufactured (kg) 1.0 ON - SI TE RELEASES No. of units per site 1 Release per unit installed (kg) 0.25 Release per unit serviced (kg) without recycling 2.0 with recycling 0.02 recycling efficiency 99% Release per unit operating (kg/yr) 0.20 Release per unit disposed (kg) without recycling 8.1 with recycling 0.08 recycling efficiency 99%

a Based on Carrier Transicold and Thermo King, each with one manufacturing facility, equally sharing an estimated 90 percent of 1992 production.    159 HOUSEHOLD AND OTHER REFRIGERATED APPLIANCES Ty pe/Site of Release Window A/C Units Central A/C

& Home Heat Pumps Commercial

Direct Expansion A/C MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 300,000 a 400,000 a 38,600 b Release per unit manufactured (kg) 0.05 0.23 0.33 ON - SI TE RELEASES No. of units per site 1 1 1 Release per unit installed (kg) 0 0 11 Release per unit serviced (kg) without recycling 1.8 3.8 33 with recycling 0.04 0.08 0.66 recycling efficiency 99% 99% 99% Release per unit operating (kg/yr) 0.38 0.80 6.9 Release per unit disposed (kg) without recycling NA 3.8 33 with recycling NA 0.04 0.33 recycling efficiency NA 99% 99% DI SPOSAL RELEASES - RECYCLING/SALVAGING CENTER No. of units processed per site per ye ar 26,000 c NA NA Release per unit processed (kg) without recycling 1.8 NA NA with recycling 0.02 NA NA recycling efficiency 99% NA NA NA = Not applicable

a There are 40 manufacturers of home air conditioning units. W e assume the largest manufacturer has 10 percent o f the total market share. b Assumes five manufacturers of commercial air conditioning equipment with an equal market share for each. c Actual processing data for Appliances Recycling Centers of America (ARCA) facility in Minneapolis, MN.    160 HOUSEHOLD AND OTHER REFRIGERATED APPLIANCES Ty pe/Site of Release Refrigerator s and Freezers Other

Refrigerated Appliances MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 750,000 a 170,000 b Release per unit manufactured (kg) 0.04 0.04 ON - SI TE RELEASES No. of units per site 1 1 Release per unit installed (kg) 0 0 Release per unit serviced (kg) without recycling 0.41 0.50 with recycling 0.02 0.03 recycling efficiency 95% 95% Release per unit operating (kg/yr) 0.40 c 0.50 c Release per unit disposed (kg) without recycling NA 0.50 with recycling NA 0.03 recycling efficiency NA 95% DI SPOSAL RELEASES - RECYCLING/SALVAGING CENTER No. of units processed per site per ye ar 17,000 d 2,400 e Release per unit processed (kg) without recycling 0.40 0.41 with recycling 0.02 0.02 recycling efficiency 95% 95% NA = Not applicable

a There are 25 manufacturers o f domestic refrigerators and freezers. W e assume the largest manufacturer has 10 percent of the total market share. b There are 25 manufacturers of other refrigerated appliances. A ssumes that the largest manufacturer has 10 percent of total market s hare. c Refrigerators and freezers and other refrigerated appliances have hermetically sealed systems and rarely leak. I f they do le ak, however, they are likely to lose their entire charge -- the value represented in this table. d Actual processing data for Appliances Recycling Centers of America (ARCA) facility in Minneapolis, MN. e Data for dehumidifiers only.    161 MOBILE AIR CONDITIONERS Ty pe/Site of Release Mobile Air Conditioners MANUFACTURING RELEASES - FACTORY No. of units manufactured per plant per ye ar 325,000 a Release per unit manufactured (kg) 0.11 INSTA LLATION RELEASES - SERVI CE STATION No. of units per site 63 b Release per unit installed (kg) 0.11 SERVI CI NG RELEASES - SERVI CE STATION No. of units serviced per site per year 165 c Release per unit serviced (kg) without recycling 1.2 with recycling 0.06 recycling efficiency 95% DI SPOSAL RELEASES - RECYCLING/SALVAGING CENTER No. of units processed per site per ye ar 4,250 d Release per unit processed (kg) without recycling 1.2 with recycling 0.06 recycling efficiency 95%

a The Motor Vehicle Manufacturers Association (MVMA) reports that the capacity of one of the largest auto manufacturing plants (H onda Civic plant in Marysville, Ohio) is 360,000 cars per year. E ighty five percent of new cars are assumed to have factory- installed MACs. b Mobile air conditioners installed after car purchase at the customer's request (referred to as after- market MACs) would experience leak testing and fill - related emissions at the installation site instead of the auto factory. W e assume that all dealerships that service MACs also install MACs (23,550 dealerships [MACs RIA]). c This is the numbers of MACs typ ically serviced in a large shop (MACs RIA) d Assumes that 17 MACs are processed per day, 250 days per year.**ATTACHMENT 7 -**  **C**

**METHODOLOGY FOR ESTIMATING GENERAL POPULATION EXPOSURES TO AMBIENT AIR RELEASES OF SUBSTITUTES FOR CLASS I SUBSTANCES**  **FOR SNAP RISK SCREENS** The approach used to estimate general population exposures to ambient air releases of substitutes for Class Iozone - depleting substances (ODSs) for the SNAP risk screens is patterned after the approach EPA used previousl y (EPA 1990a) for the interim report on HFCs and HCFCs (EPA 1990b). T he sections below summarize EPA's earlier approach and discuss how it was applied to the SNAP risk screens. **SUMMARY OF EPA'S EARLIER APPROACH FOR ESTIMATING GENERAL PO**  **PULATION EXPOSURES** EPA's approach for estimating gen eral population exposures for the interim report on HFCs and HCFCs is summarized in the two documents referred to above. E PA used information developed b y PEI (EPA 1990c), combined with engineering judgment, to develop estimates of ambient air releases from each of the activities shown in Exhibit 7 - C - 1. E PA then used the Industrial Source Complex L ong Term (I SCLT) Dispersion Model to estimate ambient air concentrations at an assumed exposure point. The I SCLT model is a steady - state Gaussian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial source complex. A dditional information on the model can be found in EPA's Industrial Source Complex (ISC) Dispersion Model User's Guide (EPA 1 986) and addendum (EPA 1987). T he model has not been through Science Advisory Bo ard or formal external peer review, but it has been reviewed and recommended for general use b y EPA's Office of Air Quality Planning and Standards for applications similar to this. To run the ISCLT model, it was necessary fo r EPA to develop inputs for source characteristics and meteorological factors. ! EPA used engineering judgment to develop assumptions about the characteristics of the facilities (e.g., stack height, surf ace area) from which the ODSs are released. ! EPA used meteorological conditions for a "generic" site, which was selected based on an anal ys is of maximum exposed individual concentrations calculated for an identical release from each of 392 sites across the U.S. T he meteorological conditions at this generic site were known to cause conservative estimates of exposure point concentrations. EPA then used the I SCLT model outputs to estimate concentrations at the fenceline of the release site. D istances to the fenceline varied depending on the ty pe of release site, and were based on professional judgment. E PA points out that for some types of release sites, the model was unable to predict concentrations as close as the assumed fenceline distance. In these c ases, the exposure estimates were based on the highest concentrations predicted b y the model. EPA documents several areas of uncertainty associated with the release, concentration, and exposure estimates; these are not repeated here.**APPLYING EPA'S EARLIER APPROACH TO THE SNAP RISK SCREENS** 

For the SNAP risk screens, general population exposures to ambient air releases of Class I substances were estimated using three basic steps: (1) The first step was to update the ambient air release in formation presented in the EPA report (EPA 1990c) using more recent data. Conservative estimates were made of annual ambient air releases of ODS substitutes from different types of facilities (e.g., chemical manufacturing plants, factories that produce equipment containing the substitutes, sites at which the substitutes are used, service stations, centralized recycling or disposal facilities); (2) Each t ype of release site was "matched up" with one that was modeled earlier b y EPA; and (3) The results of the previous I SCL T runs were used to determine the relationship between the release rate and exposure point concentration for each type of release site; that factor was then applied to the revised release estimates to derive a new fenceline concentration. Steps (1) and (3) were straightforward. T he approach used to calculate releases from different ty pes of facilities (Step 1) is described in the section documenting the general population exposure anal ys is for each use sector. T o determine the relationsh ip between releases and fenceline concentrations (Step 3), EPA's contractor for the earlier anal ys is (Versar) provided a table identifying the "normalized maximum concentration at the fenceline,  g/m 3 " for each of the runs conducted for the interim report. These normalized maximum concentrations, shown in Exhibit 7 - C - 1, are the maximum fenceline concentrations that result from the release of one gram per second (g/sec) of ODS from a source. U sing them is simply a matter of converting estimated annual rele ases to g/sec and multiplying them by the normalized concentration, yi elding maximum fenceline concentrations in  g/m 3

. Some difficulties were encountered in the second step, however, which add to the uncertainties associated with the ambient air modeling. T hese difficulties arise from two factors, discussed below. ! First, it was sometimes difficult to identify the t yp e of facility

associated with each normalized concentration listed in Exhibit 7 - C - 1. T his is because the normalized concentratio ns are presented by t ype of activity (e.g., manufacturing, servicing) rather than ty pe of source (e.g., factory , operating site, service station). T o cross - walk the normalized concentrations provided in Exhibit 7 - C - 1 with different types of release sites for the SNAP    4

risk screens, EPA examined the model input parameters and patterns among the normalized concentrations themselves. E PA believes that the ty pes of release sites associated with each normalized concentration were identified accuratel y using thi s approach. ! Second, and more importantly , the SNAP risk screens cover certain end uses that were not covered in the general population exposure portion of the interim anal ys is because the end uses were believed to consume relativel y sm all amounts of ODS s. B ecause the SNAP risk screens attempt to cover all end uses, normalized concentrations were needed for source ty pes not previously modeled. P rofessional judgment was used to select which normalized concentrations (among those listed in Exhibit 7 - C - 1) to use for source types that were not modeled earlier. Exhibit 7 - C - 2 lists the normalized concentrations that EPA used for each source type in the SNAP analy ses of general population exposure to ambient air releases.    5 **EXHIBIT 7**  **- C**  **- 1**  **NORMALIZED FENCELINE CONCENTRATIONS (EPA/VERSAR)** SECTOR ACTIVITY TYPE OF RELEASE NORMALIZED

MAX. FENCELINE CONC. ( g/m 3 ) CHEMI CAL MANUFACTURING Manufacture of CFCs Stack 8.9

Manufacture of CFCs Area 60.4 REFRIGERATION Retail Food: Manuf./Install. Volume 166.3

Retail Food: Servicing Volume 864.8 CSW: Manuf./Install. Volume 102.5 CSW: Servicing Volume 102.5 Chillers: Manuf./Install. Volume 166.3 Chillers: Servicing Volume 40.7 Ice Makers: Manuf. Volume 166.3 Ice Makers: Servicing Volume 864.8 Ice Skate Rinks: Manuf. Volume 254.8 Ice Skate Rinks: Servicing Volume 254.8 MACs: Manuf. Volume 58.8 MACs: Servicing Volume 864.8 Chem. Proc. & Refineries: Manuf. Area 56.7 Chem. Proc. & Refin.: Servicing Area 56.7 FOAM BLOWING Foam Blowing: Rigid & Flexible Stack 6.2 Foam Blowing: Rigid & Flexible Volume 62.4 SOLVENTS PC Board Cleaning Stack 9.6 a

PC Board Cleaning Volume 166.3 Other Electronics Cleaning Stack 9.6 a Other Electronics Cleaning Volume 472.7 Metal Cleaning Stack 9.6 a Metal Cleaning Volume 166.3 STERILIZATION Sterilization Volume 40.7

a Normalized maximum concentrations for stack releases for the solvents sector were not provided by V ersar. T hese values were back - calculated based on the releases and fenceline concentrations provided in the earlier EPA reports.    6 **EXHIBIT 7 -**  **C -**  **2 NORMALIZED MAXIMUM CONCENTRATIONS (**  **g/m 3**  **) APPLIED TO DIFFERENT**

**TYPES OF RELEASE SITES FOR SNAP RISK SCREENS** SECTOR END USE FACTORY RELEASE S OPERATI

NG SI TE RELEASES SERVI CE

STATION RELEASE S DI SPOSAL

SI TE RELEASES b CHEMI CAL MANUFACTURE Manufacture

of CFCs Stack: 8.9

Area: 60.4 NA NA NA REFRIGERATION Retail Food 166.3 864.8 NA NA

CSW **166.3** 102.5 NA NA Chillers 166.3 40.7 NA NA Ice Makers 166.3 864.8 NA NA Ice Rinks **166.3** 254.8 NA NA MACs 58.8 NA 864.8 **56.7** ChProc & Ref **166.3** 56.7 NA NA Transport Ref **166.3 864.8**  NA NA Home Appliances **166.3 864.8**  NA **254.8** Commercial A/C **166.3 254.8**  NA NA FOAM BLOWING Flexible

Foam **6.2** NA NA NA Other End Uses 62 NA NA NA SOLVENT CLEANING Cleaner

Formulation Stack: **8.9**

Area: **60.4** NA NA NA PC Board Cleaning NA Stack: **9.6** Volume: 166.3 NA NA Other Electron. Cleaning NA Stack: **9.6** Volume: 472.7 NA NA Metal Cleaning NA Stack: **9.6** Volume: 166.3 NA NA STERILIZATION Sterilization NA 40.7 NA NA AEROSOL S Propellants **166.3** NA NA NA

Solvents **166.3 472.7**  NA NA HALONS Processing

and Equipment **173** NA NA NA ADHESIVES, COATINGS, AND IN KS All End Uses **166.3 166.3**  NA NA    7

a Entries in **bold** were developed for the SNAP risk screens based on a review of EPA and Versar documents; those not in bold were taken directly from Versar (see Exhibit 7 - C - 1). b Applies to cases in which equipment is transported to a centralized location (e.g., recycling center or salvaging yard) before the ODS substitute is removed.    8 **REFERENCES FOR ATTACHMENT 7 -**  **C** U.S. EPA. 1 990a. Potential Ambient Inhalation Exposures for Chlorofluorocarbon Substitutes. Office of Toxic Substances, Exposure Evaluation Division, Exposure Assessment Branch. November 7, 1990. U.S. EPA. 1 990b. External Review Draft, Hydrofluorocarbons and Hydrochlorofluorocarbons, Interim Repo rt. Office of Toxic Substances. N ovember, 1990. U.S. EPA. 1 990c. Revised Draft: Occupational Exposure and Environmental Release Data for Chlorofluorocarbons (CFCs) and Their Substitutes. Office of Toxic Substances. U.S. EPA. 1 986. Industrial Source Complex (ISC) Dispersion Model User's Guide, Second Edition, Volumes 1 and 2 . P ublication Nos. EPA - 450/4 - 86 - 005a, and - 005b. U .S. Environmental Protection Agency , Research Triangle Park, NC. (NTI S PB86 234259 and PB86 234267). U.S. EPA. 1 987. Industrial Source Complex (ISC) Dispersion Model. A ddendum to the User's Guide. U.S. Environmental Protection Agency , Research Triangle Park, NC.    9 **ATTACHMENT 7 -**  **D NOTE**  The disposal scenario for household and other refrigerated appliances in cluded emissions from the refrigerators and freezers, dehumidifiers (part of the "other refrigerated appliances" category), and window air conditioners sectors. S ince all three kinds of equipment could conceivabl y be disposed of at the same salvage locati on, for the purposes of maintaining the conservative nature of this analy sis, ratios should be summed for any substitutes that are common across these sectors. T he resulting ratios are: Substitute Ratio w/Recycling Ratio w/o Recycling Cancer Risk HCFC - 22 9.7E - 05 N/A 3.8E - 08 HCFC - 124 2.2E - 06 N/A N/A HFC - 134a 4.9E - 04 4.4E - 02 N/A HFC - 152a 1.2E - 04 1.1E - 02 N/A None of the resulting summed ratios are high enough to be considered of concern.    10 **ATTACHMENT 7 -**  **E Percent of Equipment with Assumed Charge Size**  END USE Charge Size (Kgs) Percent of

Total in End Use Category Comments Retail Food - Parallel 466 100 Retail Food - Stand alone 19 50 other 50% are 10 kg Cold Storage Warehouses 250 100 Reciprocating Chillers 73 100 Screw Chillers 230 100 Centrifugal Chillers - LP 450 100 Centrifugal Chillers - HP 900 70 25% are 820 kg, 5% are 540 kg Industrial Process - LP 680 100 Industrial Process High Pressure Package 180 89 11% are 145 kg Industrial Process High Pressure Built Up 9100 7 58% are 4550 kg 6% are 2200 kg 29% are 1800 kg Ice Skating Rinks 1360 52 48% are approx. 350 kg Medium Ice Makers 2.3 100 Large Ice Makers 34.1 100 Transport Refrigeration 8.1 100 Window A/C 1.8 100 Central A/C and Heat Pumps 3.8 20 75% are approx. 3 kg 5% are 0.7 kg Commercial Direct A/C 33 10 90% are 10.2 kg Refrigerators and Freezers 0.4 8 92% are between 0.19 kg and 0.33 kg Other Refrigerated Appliances 0.5 10 42% are 0.4 kg 14% are 0.2 kg 34% are 0.1 kg Mobile Air Conditioners 1.2 40 60% ar 0.88 kg**8. V**  **OLATILE ORGANIC COMPOUND ANALYSIS**

This chapter examines volatile organic compound (VOC) emissions from substitutes to Class I ozone - depleting substances (ODSs) that may be used for some end uses within the refrigeration and air conditioning sector. The VOCs of concern for this sector are the h ydrocarbons. V OCs are important to investigate as they can lead to the formation of ground - level ozone and, thus, degradation of ambient air quality and adverse health effects. This is a screening - level assessment where overly conservative, worst - case scenarios are presented. The general approach used in this analysis was to compare tot al nationwide potential emissions from sources using VOC substitutes in the refrigeration and air conditioning industry w ith total VOCs from all other sources (e.g., other industries, mobile sources, and biogenic sources). N ext, a hy pothetical sample area (the Trane facility

in the city

of Indianapolis) was chosen to demonstrate a worst - case air emission situation. T he estimated potential emissions from a facility that had switched to VOCs were added to a per - capita emissions amount (to account for releas es from refrigeration and air conditioning units already in operation) and compared with the total VOC emissions from all other sources. These comparisons give an indication of the potential impact of Class I substitutes in this sector on VOC emissions and the resulting formation of ground - level ozone. **8.1 VOC EMISSIONS FROM SUBSTITUTES TO CLASS I ODSs**  To estimate VOC releases from ODS substitutes in the refrigerant and air conditioning industry , the estimated 1992 nationwide release of ODSs were examin ed in all refrigerant and air conditioning end uses for which hydrocarbons have been suggested as substitutes. T he ye ar 1992 was chosen based on the assumption that the effects of the CAA phaseout mandate would not begin until after 1991 or 1992. The rel ease estimates are from the Vintaging Model. w For the purposes of this screening - level anal ys is, it was assumed that hydrocarbons would capture 100 percent of the market share for substitutes to Class I O DSs in 1992, and that the replacement factor for su bstituting a Class I substance with a VOC alternative is one. E PA believes that these assumptions grossl y overestimate the amount of VOCs that could potentially

b e released, which is consistent with the objective of conducting a screening - level assessment . **8.2 VOC EMISSIONS FROM ALL SOURCES**  The VOCs from both anthropogenic and biogenic sources are considered for purposes of this anal ys is as emissions of VOCs from all sources (i.e., background). Attachment 8 - A provides details on the calculation of total (background) VOCs from all sources. R efer to Attachment 8 - A for the breakdown of total emissions for the nation, for each of the six areas as taken from the Urban Airshed Model (UAM), and for a description of the UAM.

w See Chapter 4 for description of the Vintaging Model.**8.3 COMPARISON OF VOCS FROM**  **SUBSTITUTES TO VOCS FROM ALL SOURCES**

The comparison between total nationwide VOC emissions from all sources (21,070,000 MT) and VOC emissions from ODS substitutes in the refrigeration and air conditioning industry in 1992 (67,295 MT) results in a national increase in total VOCs of no more than about 0.32 percent. EPA does not expect to see an y significant difference between the national ratio and the regional ratios, and therefore has not estimated VOC increases in detail for each region in Attachment 8 - A (as was done for several other sectors). H owever, releases from refrigerant and air conditioning use in a concentrated area were roughl y evaluated by p lacing several of the "worst" possible hy pothetical factories in that area, assessing emissions, adding this to a per - capita emissions amount (to account for releases from units in operation), and comparing the potential VOC emissions to the total VOC emissions from all sources in that area. Inthe sample region, Trane was chosen as the f actory w ith the highest estimated potential air emissions (because of its size). It was assumed that Trane manufactures all industrial process equipment in one factory. ( Industrial process equipment factories account for some of the highest VOC releases of any

e quipment - producing factories; see the general population analy sis for more details.) From the anal ys is on general population risk for the refrigeration and air conditioning sectors, VOC releases from three of these facilities were estimated to be 74 MT/y r. N ext, the per - capita emissions were added in to account for non - factory s ources. T o do this, the 67,295 MT/y r emissions estimated from the vintaging model were used and it was assumed that there are 250 million people in the United States. Ind ianapolis a has a population of 780,000 people, yi elding a total annual release of 210 MT/y r for non - factory

s ources. T otal VOCs from hydrocarbon substitutes in the refrigerant and air conditioning sector in Indianapolis thus is estimated at 284 MT/yr. T h is increase is 0.43 percent of the total VOCs from all sources in In dianapolis (66,640 tons). U sing data from Systems Applications International (SAI), b and the assumption that one month of VOC emissions (23.67 MT) occurs instantaneously

and enters a 3,00 0 foot high column of air over Indianapolis (which has an area of approximately

1 0 12 m 2 ), ozone levels would increase by a bout 12.8 ppt. When added to Indianapolis' current ozone level of 0.121 ppm, the increase would be insignificant, especiall y compared to the amount needed to change In dianapolis' ozone classification to the next worse nonattainment level (i.e., moderate at 0.138 ppm ozone). **8.4 CAVEATS AND LIMITATIONS**  EPA believes that actual VOC increases due to refrigerants will be less than presented here for several reasons, including:

 VOC emissions controls required by E PA and the states will likely b e used (Attachment 8 - B describes the expected impact of VOC controls);

 Improved waste minimization and other housekeeping techniques will likely be used;

a Indianapolis was chosen because it was the area from Attachment 8 - A with th e smallest amount of total VOCs, and thus is the most sensitive to percent changes in total VOCs. b This mass -balance model was developed by ICF Incorporated as a simple screening - level tool for calculating a "bounding" estimate of VOC increases from ODS substitutes. T his model was not peer - reviewed by EPA, nor was it developed for purposes of determining a central tendency or even a high end estimate of potential increases in VOC concentrations.  13

 VOCs will not have 100 percent of the market share.  14 **CHAPTER 8 REFERENCES** Reid, Steven. S ys tems Applications International (SAI). 1 990. M ay - June. S an Rafael, CA. Personal communication.**ATTACHMENT 8 -**  **A**

**ESTIMATION OF TOTAL VOC EMISSIONS FROM ALL SOURCES IN 1995** The estimates for total VOC emissions from all sources incorporate both anthropogenic (including mobile sources) and biogenic sources. F or Los Angeles, Philadelphia, Atlanta, and Dallas, estimates of VOC emissions for 1995 were extracted directl y from the latest Urban Airshed Modela results (June 1990). F or Indianapolis and Hennepin, VOC emissions estimates for 1995 were not available (nor were estimates for an y other marginal nonattainment or attainment area). S imilarly , anthropogenic and biogenic estim ates were not readily available for nationwide 1995 VOC emissions. T herefore, anthropogenic emissions for 1985 were first obtained from the National Acid Precipitation Assessment Program (NAPAP) emissions inventory . T hese 1985 figures then were adjusted for 1995 using economic indicator data from the Bureau of Economic Anal ys is (BEA) Regional Projections Data System (June 1990). T he biogenic emissions were obtained by averaging seasonal biogenic VOC data from the Regional Biogenic Emissions Inventory Sys tem (1990) b

. T hese biogenic emissions were assumed to remain the same for 1995. T he figures obtained from this analy sis are presented in Exhibit 8 - A - 1. **EXHIBIT 8 -**  **A -**  **1**

**TOTAL VOC EMISSIONS FROM ALL SOURCES IN 1995 (TONS) Area**  **Current**

**Status Anthro**  **pogenic**

**Emissions Biogenic** 

**Emissions Total VOC** 

**Emissions** Los Angeles, CA Extreme

Nonattainment 762,485 295,285 1,057,770 Philadelphia, PA Severe

Nonattainment 760,295 230,315 990,610 Atlanta, GA Serious

Nonattainment 244,550 466,105 710,655 Dallas, TX Moderate

Nonattainment 360,620 253,310 613,930 Indianapolis, IN Marginal

Nonattainment 71,588 1,718 73,306 Hennepin, MN Attainment 82,022 2,078 84,100 United States -- -- -- 23,176,700

a UAM, managed by Systems Application International (SAI), is a three dimensional photochemical grid model designed to calculate concentrations of both inert and chemically reactive pollutants by simulating physical and chemical processes that occur in the atmosphere. UAM is EPA's recommended model for p hotochemical pollutant modeling applications involving entire urban areas. F or more information, see: S ystems Applications, Inc., User's Guide for the Urban Airshed Model , developed by SAI for Office of Air Quality Planning and Standards, June 1990. b Systems Applications International. 1 990. VOC Analysis Support . M emorandum from Steve Reid, SAI, to Shailendra Reddy, ICF. M arch 19, 1990.**ATTACHMENT 8 -**  **B VOC CONTROLS**  Facilities in ozone nonattainment areas switching from ODSs to VOCs may be required to offset the VOC emissions from their facility s o that net VOC emissions decrease within the nonattainment area. Within nonattainment areas, major sources of emissions are subject to the provisions of the New Source Review (NSR) program. T his program requires affected sources to reduce emissions to the lowest achievable emissions rate (LAER), and to offset new VOC emissions increases with reductions obtained within the fa cility

or at other facilities located within the nonattainment area. The NSR program affects "major sources" in nonattainment areas, and the d efinition of major source depends primarily u pon the potential of the source to emit pollutants (potential emiss ions). Potential emissions are the amount of pollutant the source is capable of emitting in the absence of any federally e nforceable emission limitation. T hese amounts are similar to those estimated for individual facilities in the SNAP analyses. T he po tential emissions necessary f or a source to be defined as major is a function of the classification of the ozone nonattainment area, with the amount of emissions necessary to be defined as a major source becoming smaller as ozone nonattainment problems of the area become greater (Exhibit 8 - B - 1). **EXHIBIT 8 -**  **B -**  **1**

**MAJOR SOURCE DEFINITION AND OFFSET REQUIREMENTS** Nonattainment Area Classification Major Source Definition (Tons per Year) Offset Ratios (VOC reduct.:VOC incr.) Marginal 100 TPY 1.1 : 1 Moderate 100 TPY a 1.15 : 1 Serious 50 TPY a 1.2 : 1 Severe 25 TPY a 1.3 : 1 Extreme 10 TPY a 1.5 : 1

a States have the option of electing to define major source at 5 tons/y r (and accepting other conditions) as opposed to demonstrating further reasonable progress. S ee text. It should be noted that some states may e lect to opt out of the reasonable furthe r progress (RFP) demonstration required by the CAA, which requires states with some classifications of nonattainment areas to demonstrate a 15 percent reduction in VOC emissions within the first six ye ars of enactment (i.e., by N ovember 1996). S tates elec ting to opt out of the RFP demonstration must define major source at the 5 ton/y

r level and accept other conditions. The CAA also requires that major sources in nonattainment areas an y o ffset any n ew VOC emissions with reductions in VOC emissions from w ithin their facility o r from other facilities located within the nonattainment area. T his offset requirement results in a net decrease in VOC emissions for sources affected by

the NSR program. A s shown in Exhibit 8 - B - 1, the required offsets are a functio n of the classification of the nonattainment area and increase with increasing ozone nonattainment status. Sources affected by

the NSR program are also required to reduce emissions to LA ER. LAER determinations are ty

pically b ased on the minimum expected performance of air pollution controldevices. T he reductions achievable by c ontrol devices are well established and as shown in Exhibit 8 - B - 2 exceed 95 percent. **EXHIBIT 8 -**  **B -**  **2**

**EFFECTIVENESS OF COMMON VOC CONTROL DEVICES** Control Device Minimum Expected Reduction Efficiency

(Percent) Thermal Oxidizer 98% Carbon Absorber 95% Condenser 95% Because facilities switching to VOCs would be required to install LAER, and controls are capable of reducing emissions by

9 5 percent, EPA would expect the projected increases in VOC from NSR affected facilities to be reduced by at least 95 percent. T hese facilities must offset any residual emissions (i.e., the remaining 5 percent) by the amount specified in Exhibit 8 - B - 2, thus mitigating an y impacts from switching from ozone depleting substances to VOCs.