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TABLE 9 TO SUBPART IIIII OF PART 63.—APPLICABILITY OF GENERAL PROVISIONS TO SUBPART IIIII—Continued

Applies to Subpart Citation Subject IIIII Explanation

§ 63.10(d)(3) ...... Reporting Opacity or VE Observations No ...... Subpart IIIII does not have opacity and visible emission standards. § 63.11 ...... Flares ...... No ...... Subpart IIIII does not require flares. § 63.12 ...... Delegation ...... Yes. § 63.13 ...... Addresses ...... Yes. § 63.14 ...... Incorporation by Reference ...... Yes. § 63.15 ...... Availability of Information ...... Yes.

[FR Doc. 02–15873 Filed 7–2–02; 8:45 am] A–2002–09, U.S. EPA, 401 M Street, Standards Division, U.S. EPA, Research BILLING CODE 6560–50–P SW., Washington, DC 20460. Triangle Park, NC 27711. The EPA will Public Hearing. If a public hearing is disclose information identified as CBI held, it will be held at the new EPA only to the extent allowed by the ENVIRONMENTAL PROTECTION facility complex in Research Triangle procedures set forth in 40 CFR part 2. AGENCY Park, North Carolina. If no claim of confidentiality Docket. Docket No. accompanies a submission when it is 40 CFR Part 63 A–2002–09 contains supporting received by the EPA, the information information used in developing the may be made available to the public [FRL–7229–6] notice of proposed action for the without further notice to the Chlorine Production source category. commenter. National Emission Standards for The docket is located at the U.S. EPA, Public Hearing. Persons interested in Hazardous Air Pollutants: Chlorine and 401 M Street, SW., Washington, DC presenting oral testimony or inquiring Hydrochloric Acid Emissions From 20460 in Room M–1500, Waterside Mall as to whether a hearing is to be held Chlorine Production (ground floor), and may be inspected should contact Cassie Posey, telephone from 8:30 a.m. to 5:30 p.m., Monday number: (919) 541–0069. Persons AGENCY: Environmental Protection through Friday, excluding legal Agency (EPA). interested in attending the public holidays. hearing must also call Cassie Posey to ACTION: Proposed decision not to FOR FURTHER INFORMATION CONTACT: Mr. verify the time, date, and location of the regulate. Iliam Rosario, Metals Group, Emission hearing. The public hearing will provide SUMMARY: EPA proposes not to regulate Standards Division (C439–02), U.S. interested parties the opportunity to chlorine and hydrochloric acid (HCl) EPA, Research Triangle Park, North present data, views, or arguments emissions for the Chlorine Production Carolina 27711, telephone number: concerning the proposed emission source category. We have determined (919) 541–5308, facsimile: (919) 541– standards. that no further control is necessary 5600, electronic mail address: Docket. The docket is an organized because chlorine and HCl have well- [email protected]. and complete file of all the information defined health thresholds, and chlorine SUPPLEMENTARY INFORMATION: considered by the EPA in rule and HCl air emissions from chlorine Comments. Comments and data may be development. The docket is a dynamic producers result in human exposures in submitted by electronic mail (e-mail) to: file because material is added the ambient air that are below the [email protected]. Electronic throughout the rulemaking process. The threshold values with an ample margin comments must be submitted as an docketing system is intended to allow of safety. This notice does not address ASCII file to avoid the use of special members of the public and industries mercury emissions from mercury cell characters and encryption problems and involved to readily identify and locate chlor-alkali plants. Those emissions are will also be accepted on disks in documents so that they can effectively addressed in a separate action in the WordPerfect format. All comments and participate in the rulemaking process. proposed rule section of this Federal data submitted in electronic form must Along with the proposed and Register. note the docket number: Docket No. A– promulgated standards and their 2002–09. No confidential business preambles, the contents of the docket DATES: Comments. Submit comments on information (CBI) should be submitted will serve as the record in the case of or before September 3, 2002. by e-mail. Electronic comments may be judicial review. (See section 307(d) Public Hearing. If anyone contacts the filed online at many Federal Depository (7)(A) of the Clean Air Act (CAA).) The EPA requesting to speak at a public Libraries. materials related to this notice of hearing by July 23, 2002, a public Commenters wishing to submit proposed action are available for review hearing will be held on August 2, 2002. proprietary information for in the docket or copies may be mailed ADDRESSES: Comments. By U.S. Postal consideration must clearly distinguish on request from the Air Docket by Service, send comments (in duplicate if such information from other comments calling (202) 260–7548. A reasonable fee possible) to: Air and Radiation Docket and clearly label it as CBI. Send may be charged for copying docket and Information Center (6102), submissions containing such materials. Attention Docket Number A–2002–09, proprietary information directly to the WorldWide Web (www) Information. U.S. EPA, 1200 Pennsylvania Avenue, following address, and not to the public In addition to being available in the NW, Washington, DC 20460. In person docket, to ensure that proprietary docket, an electronic copy of today’s or by courier, deliver comments (in information is not inadvertently placed notice of proposed action will also be duplicate if possible) to: Air and in the docket: OAQPS Document available through EPA’s www site. Radiation Docket and Information Control Office (C404–02), Attention: Following signature, a copy of the rule Center (6102), Attention Docket Number Iliam Rosario, Metals Group, Emission will be posted on our policy and

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guidance page for newly proposed or The CAA includes exceptions to the None of the 20 chlor-alkali plants are promulgated rules: http://www.epa.gov/ general statutory requirement to major in and of themselves, but are ttn/oarpg. The web site provides establish emission standards based on major due to collocation. That is, they information and technology exchange in MACT. Section 112(d)(4) allows us to are part of a larger contiguous various areas of air pollution control. If use discretion in developing risk-based establishment that is a major source. more information regarding the web site standards for HAP ‘‘for which a health These larger establishments include is needed, call our web site help line at threshold has been established’’ organic chemical manufacturers, (919) 541–5384. provided that the standards achieve an polymer and resin producers, and pulp Regulated entities. Entities potentially ‘‘ample margin of safety.’’ and paper mills, all of which are already affected by this action include facilities subject to one or more NESHAP. For B. What Is the Source Category? engaged in the production of chlorine. instance, the organic chemical Affected categories and entities include The Chlorine Production source manufacturers are subject to the those sources listed in the primary category was initially listed as a major Hazardous Organic NESHAP, or HON Standard Industrial Classification code source of HAP pursuant to section (40 CFR part 63, subparts F, G, and H). 2812 or North American Information 112(c)(1) of the CAA on July 16, 1992 The HON is a comprehensive rule that Classification System code 325181. (57 FR 31576). At the time of the initial covers process vent, transfer, storage This description is not intended to be listing, we defined the Chlorine tank, equipment leak and wastewater exhaustive, but rather provides a guide Production source category as follows: emissions from the production of almost for readers regarding entities likely to be * * * The Chlorine Production Source 400 organic chemicals. More than 100 affected by this action. If you have Category includes any facility engaged in the organic HAP are regulated under the questions regarding the applicability of production of chlorine. The category HON. this action to a particular entity, consult includes, but is not limited to, facilities Polymers and resins producers are the person listed in the preceding FOR producing chlorine by the following subject to four separate NESHAP (40 FURTHER INFORMATION CONTACT section. production methods: diaphragm cell, CFR part 63, subparts U, W, JJJ, and Outline. The information presented in mercury cell, membrane cell, hybrid fuel cell, OOO) and must control process vent, this preamble is organized as follows: Downs cell, potash manufacture, transfer, storage tank, equipment leak hydrochloric acid decomposition, nitrosyl I. Background and wastewater emissions. Chlor-alkali chloride process, nitric acid/salt process, Kel- facilities that are collocated with pulp A. What is the source of authority for Chlor process, and sodium chloride/sulfuric development of NESHAP? acid process. and paper mills are covered by 40 CFR B. What is the source category? part 63, subpart S (Pulp and Paper C. What are the health effects of chlorine We know of no facilities that produce MACT III) and 40 CFR part 63, subpart and hydrogen chloride? chlorine using hybrid fuel cells, the KK (Printing and Publishing MACT). II. Summary of Proposed Action nitrosyl chloride process, the Kel-Chlor Chlor-alkali production facilities are III. Rationale for Proposed Action process, the sodium chloride/sulfuric also collocated with the following A. What is our statutory authority under section 112(d)(4)? acid process, or as a by-product from source categories: hazardous waste B. What is the basis for our proposed potash manufacturing. We have pesticide active ingredients production action? identified 45 facilities that produce (subject to 40 CFR part 63, subpart IV. Solicitation of Comments and Public chlorine using mercury cells, diaphragm MMM), polyether polyols production Participation cells, or membrane cells. Collectively, (subject to 40 CFR part 63, subpart PPP), these facilities are referred to as chlor- and polycarbonates production (subject I. Background alkali plants as they produce chlorine to 40 CFR part 63, subpart YY). There A. What Is the Source of Authority for and alkali (sodium hydroxide) as co- is also the Miscellaneous Organic Development of NESHAP? products. Chemical Products and Processes Section 112 of the CAA contains our We have also identified three facilities NESHAP, currently under development, authority for reducing emissions of that produce chlorine as a by-product: which will cover a variety of smaller, hazardous air pollutants (HAP). Section one from the production of sodium specialty chemical manufacturing 112(d) requires us to promulgate metal in Downs cell, another from the processes, many that utilize chlorine. regulations establishing emission production of potassium nitrate Therefore, most major processes at the standards for each category or fertilizer that uses the nitric acid/salt sites where chlor-alkali facilities are subcategory of major sources and area process, and a third that produces located are subject to, or will be subject sources of HAP listed pursuant to chlorine as a by-product from primary to, NESHAP to reduce HAP emissions. section 112(c). Section 112(d)(2) magnesium refining. In addition, we In addition to NESHAP, the chlorine specifies that emission standards have identified a resin producer that production facilities are themselves promulgated under the section shall produces chlorine both in a chlor-alkali subject to rules pursuant to section require the maximum degree of plant and through the decomposition of 112(r) of the CAA for the prevention of reductions in emissions of the HAP HCl. accidental releases of chemicals (40 CFR subject to section 112 that are deemed Of the 48 facilities that produce part 68). achievable considering cost and any chlorine, we have identified 21 that are The primary HAP emitted from non-air quality health and major sources, including 20 chlor-alkali chlorine production facilities processes 1 environmental impacts and energy plants and the one primary magnesium are chlorine and HCl. In each of the requirements. refining facility. The primary three chlor-alkali electrolytic cell National emission standards for magnesium refining facility is itself a processes, an electric current is passed hazardous air pollutants (NESHAP) major source emitting on the order of through a salt solution (brine) causing reflect the maximum degree of 600 tons of chlorine and 3,000 tons of the dissociation of salt to produce reduction in emissions of HAP that is HCl yearly, and is, in fact, a separately 1 The mercury cell chlor-alkali process also emits achievable. This level of control is listed source category. As such, it will mercury. Those emissions are addressed in a commonly referred to as maximum be addressed on its own in a separate separate proposal elsewhere in today’s Federal achievable control technology (MACT). rulemaking. Register.

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chlorine gas and an alkaline solution. edema in humans. Chronic occupational threshold level for an individual Chlorine is collected from the cell room exposure to HCl has been reported to exposed at the upper end of the and is cooled, dried, and condensed in cause gastritis, bronchitis, and exposure distribution. The upper end of the purification process. The dried, dermatitis in workers. Prolonged the exposure distribution is calculated gaseous chlorine then may be cooled exposure to low concentrations may using the ‘‘high end exposure estimate,’’ further and compressed and liquified also cause dental discoloration and defined as a plausible estimate of using multiple-stage condensers in the erosion. No information is available on individual exposure for those persons at compression/liquefaction operation. the reproductive or developmental the upper end of the exposure Chlorine can be emitted from the tail gas effects of HCl in humans. In rats distribution, conceptually above the stream from the final liquefier, the cell exposed to HCl by inhalation, altered 90th percentile, but not higher than the room, and equipment in chlorine estrus cycles have been reported in individual in the population who has service. Hydrochloric acid is used to females and increased fetal mortality the highest exposure. We believe that pretreat feed brine prior to entering a and decreased fetal weight have been assuring protection to persons at the chlor-alkali cell and at other locations reported in offspring. We have not upper end of the exposure distribution throughout the process to adjust pH. It classified HCl for carcinogenicity. is consistent with the ‘‘ample margin of can also be emitted from storage tanks safety’’ requirement in section 112(d)(4). II. Summary of Proposed Action and equipment in HCl service. We emphasize that the use of section Since chlor-alkali processes produce We are proposing not to regulate 112(d)(4) authority is wholly both chlorine and hydrogen, it is chlorine and HCl emissions from discretionary. As the legislative history common for a direct synthesis HCl chlorine production processes. Under indicates, cases may arise in which production unit to be incorporated into the authority of section 112(d)(4), we other considerations dictate that we a chlor-alkali facility. This is the have determined that no further control should not invoke this authority to situation at four of the 20 chlor-alkali is necessary because chlorine and HCl establish less stringent standards, facilities at major source plant sites. In are ‘‘health threshold pollutants,’’ and despite the existence of a health effects the direct synthesis process, chlorine chlorine and HCl levels emitted from threshold that is not jeopardized. For and hydrogen are burned together to chlorine production processes are below instance, we do not anticipate that we produce HCl. The gaseous HCl stream is their threshold values within an ample would set less stringent ‘‘risk-based’’ then routed to an absorber and margin of safety. Further, due to the fact standards where evidence indicates a concentrated to produce a liquid HCl that these two pollutants are the only threat of significant or widespread product. In many instances at chlor- HAP emitted in significant quantities environmental effects, although it may alkali facilities, gaseous chlorine- from chlorine production plants, we are be shown that emissions from a containing waste streams (such as the proposing not to develop any NESHAP particular source category do not tail gas from the liquifiers) provide for the Chlorine Production source approach or exceed a level requisite to chlorine to the HCl production unit. category, with the exception of a protect public health with an ample Therefore, we consider these direct NESHAP for mercury emissions from margin of safety. We may also elect not synthesis HCl production units to be a mercury cell chlor-alkali plants. to set less stringent risk-based standards part of the chlor-alkali facilities. These where the estimated health threshold for direct synthesis HCl production units III. Rationale for Proposed Action a contaminant is subject to large can emit HCl from the absorber vent and This section explains the statutory uncertainty. Thus, in considering associated storage vessels and transfer basis for considering health thresholds appropriate uses of our discretionary racks. when establishing standards, and the authority under section 112(d)(4), we basis for today’s proposed action, consider other factors in addition to C. What Are the Health Effects of including a discussion of the risk health thresholds, including uncertainty Chlorine and Hydrogen Chloride? assessment conducted to support the and potential ‘‘adverse environmental Acute (short-term) exposure to high ample margin of safety decision. effects,’’ as that phrase is defined in levels of chlorine in humans can result section 112(a)(7). in chest pain, vomiting, toxic A. What Is Our Statutory Authority pneumonitis, and pulmonary edema. At Under Section 112(d)(4)? B. What Is the Basis for Our Proposed lower levels, chlorine is a potent irritant As stated previously in this notice, Action? to the eyes, the upper respiratory tract, section 112 of the CAA includes We are proposing in today’s notice and lungs. Chronic (long-term) exposure exceptions to the general statutory not to develop NESHAP for the Chlorine to chlorine gas in workers has resulted requirement to establish emission Production source category other than in respiratory effects including eye and standards based on MACT. Of relevance the mercury standards being proposed throat irritation and airflow obstruction. here, section 112(d)(4) allows us to elsewhere in today’s Federal Register Animal studies have reported decreased develop risk-based standards for HAP for mercury cell processes. This body weight gain, eye and nose ‘‘for which a health threshold has been decision is based on the following. First, irritation, non-neoplastic nasal lesions, established’’ provided that the standards we consider chlorine and HCl to be and respiratory epithelial hyperplasia achieve an ‘‘ample margin of safety.’’ threshold pollutants. Second, we have from chronic inhalation exposure to Therefore, we believe we have the defined threshold values in the form of chlorine. No information is available on discretion under section 112(d)(4) to Inhalation Reference Concentrations the carcinogenic effects of chlorine in develop risk-based standards which (RfC) and acute exposure guideline humans from inhalation exposure. We may be less stringent than the levels (AEGL). Third, chlorine and HCl have not classified chlorine for potential corresponding floor-based MACT are emitted from chlorine production carcinogenicity. standards for some categories emitting plants (in the absence of additional Hydrogen chloride is corrosive to the threshold pollutants. control) in quantities that result in eyes, skin, and mucous membranes. In deciding standards for this source human exposure in the ambient air at Acute inhalation exposure may cause category, we seek to assure that levels well below the threshold values eye, nose, and respiratory tract irritation emissions from every source in the with an ample margin of safety. Finally, and inflammation and pulmonary category or subcategory are less than the there are no adverse environmental

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effects associated with these pollutants. chemicals, and emissions particular to assessment. Acute exposure guideline The bases and supporting rationale for this category. level toxicity values are estimates of these conclusions are provided in the adverse health effects due to a single Hazard Identification and Dose- following sections. exposure lasting 8 hours or less. The Response Assessment confidence in the AEGL (a qualitative 1. Threshold Pollutants The RfC is a ‘‘long-term’’ threshold, rating or either low, medium, or high) For the purposes of section 112(d)(4), defined as an estimate of a daily is based on the number of studies several factors are considered in our inhalation exposure that, over a lifetime, available and the quality of the data. decision on whether a pollutant should would not likely result in the Consensus toxicity values for effects of be categorized as a health threshold occurrence of noncancer health effects acute exposures have been developed by pollutant. These factors include in humans. We have determined that several different organizations, and we evidence and classification of the RfC for HCl of 20 micrograms per are beginning to develop such values. A carcinogenic risk and evidence of cubic meter µg/m3) is an appropriate national advisory committee organized noncarcinogenic effects. For a detailed threshold value for assessing risk to by the EPA has developed AEGL for discussion of factors that we consider in humans associated with exposure to priority chemicals for 30-minute, deciding whether a pollutant should be HCl through inhalation (63 FR 18766, 1-hour, 4-hour, and 8-hour airborne categorized as a health threshold April 15, 1998). Therefore, we used this exposures. They have also determined pollutant, please see the April 15, 1998 RfC as the threshold value in our the levels of these chemicals at each Federal Register document (63 FR exposure assessment for HCl emitted exposure duration that will protect 18766). from chlorine production plants. against discomfort (AEGL1), serious In the April 15, 1998 action cited We also considered using the RfC for effects (AEGL2), and life-threatening above, we determined that HCl, a Group chlorine. In cases where we have not effects or death (AEGL3). Hydrogen D pollutant, is a health threshold studied a chemical itself, we rely on the chloride has been assigned a 1-hour pollutant for the purpose of section studies of other governmental agencies, AEGL2 of 33,000 µg/m3. Above this 112(d)(4) of the CAA (63 FR 18753). We such as the Agency for Toxic Substances level, it is predicted that the general also believe that it is reasonable to and Disease Registry (ATSDR) or the population, including sensitive classify chlorine as a Group D pollutant. Office of Health Hazard Assessment of individuals (such as asthmatics, There have been limited animal studies California’s Environmental Protection children, or the elderly), could and observations of human occupational Agency (CAL EPA), for RfC values. The experience irreversible or other serious, inhalation exposure for chlorine. There CAL EPA developed an RfC value of 0.2 long-lasting adverse health effects, or an µ 3 has been no evidence of a carcinogenic g/m for chlorine based on a large impaired ability to escape. This value is response in chronic, subchronic, or inhalation study with rats. a medium confidence value based on acute inhalation exposures in laboratory Since chlorine does not generally the severe nasal or pulmonary animal studies or from occupational persist in the atmosphere, we evaluated histopathology observed in rats exposed inhalation exposure. Based on the the appropriateness of using this to a high concentration of 1,950,000 limited negative carcinogenicity data, chlorine RfC for this assessment. µg/m3 HCl for 30 minutes. The AEGL2 and on our knowledge of how chlorine Chlorine in the atmosphere photolyzes ¥ value for HCl is displayed in an EPA reacts in the body and its likely to chloride ions (Cl ) and then quickly internal database, the Air Toxics Health mechanism of action, we presumptively reacts with methane to form HCl in Effects Database (ATHED), as the consider chlorine to be a threshold bright sunshine. The estimated chlorine appropriate value to use in short-term pollutant. lifetime under these conditions is modeling. approximately 10 minutes. Even though 2. Health Effects Exposure Assessment Chlorine has been assigned a 1-hour emissions of chlorine in the absence of AEGL2 toxicity value of 5,800 µg/m3. We conducted a risk assessment to sunshine (e.g., at nighttime) remain as This value is based on a human determine whether the emissions of chlorine in the atmosphere until inhalation exposure study that included chlorine and HCl from chlorine sunlight emerges, we do not believe that a sensitive individual, and this AEGL production plants at the current use of the chlorine RfC was appropriate value has a high confidence value (62 baseline levels are in quantities that are for this assessment since long-term FR 58839). This AEGL2 value is also below the threshold values for chlorine exposure to significant levels of chlorine contained in EPA’s ATHED as the and HCl within an ample margin of is unlikely. EPA requests comments on appropriate value to use in short-term safety. The summary of this assessment the appropriateness of using a chlorine modeling. is organized as follows: (1) Hazard RfC to assess impacts of long-term We used these AEGL values as identification and dose-response exposure in this case. threshold values for assessing the assessment, (2) emissions and release However, we did conclude that the inhalation health effects of short-term information, and (3) exposure health effects of the long-term exposure exposures to chlorine and HCl. While assessment. to the HCl formed from the chlorine chlorine does photolyze and eventually It is important to note that the risk emitted from chlorine production plants form HCl, we concluded that it was assessment methodology applied here should be considered. Therefore, we appropriate to use the chlorine AEGL should not be interpreted as a calculated the amount of HCl that value of 5,800 µg/m3 for this assessment standardized approach that sets a would be formed from the emitted since it would be possible for precedent for how EPA will analyze chlorine and used the HCl RfC of 20 individuals to be exposed to chlorine for application of section 112(d)(4) in other µg/m3 for determining the long-term 1-hour periods at night or on cloudy cases. The approach presented here, noncarcinogenic effects of the chlorine days. including assumptions, models, and emissions. worst-case of sensitivity analysis, was In addition to these effects of long- Emissions and Release Information selected to meet the unique needs of term inhalation of HCl, we also Under the authority of section 114, we this particular case, to provide the considered whether thresholds for collected chlorine and HCl emissions appropriate level of detail and margin of short-term exposure to chlorine and HCl information for all chlorine production safety given the data availability, should be considered in this facilities at the 20 major source sites.

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Chlorine and HCl emissions were emission sources. Therefore, we exposed to annual average HCl reported for point sources and fugitive assumed an area of 2,000 square meters concentrations greater than 1 percent of emissions from the chlorine production for every fugitive emission source, the RfC. In fact, well over 99 percent units at each site. For the four sites which is a standard default used in were exposed to annual average HCl where direct synthesis HCl production modeling. concentrations less than 0.1 percent of units are part of the chlorine production Exposure Assessment the RfC. facility, emissions were also reported. To determine the impacts of short- Respondents provided maximum The exposure assessment was term exposures to chlorine and HCl annual and hourly chlorine and HCl conducted for chlorine and HCl emissions from chlorine production emissions (typically, permitted emission emissions from all chlorine production plants, we used the maximum hourly rates were provided) and release processes in the source category (i.e., emission values provided by the plants characteristics. According to the from the chlorine production processes and obtained the highest individual information submitted, plantwide at the 20 sites that are major sources of hourly concentrations from the ISCST3 annual chlorine emissions from chlorine HAP). As discussed above, the model. Separate runs were conducted production processes ranged from less emissions data and release for chlorine and HCl. The same process than one kilogram per year to over 6 characteristics provided directly from described above was used for plants that Megagrams per year (Mg/yr). Of the 20 all 20 plants were used as inputs to the did not report any fugitive emissions. plant sites, 11 reported HCl emissions assessment. The highest 1-hour chlorine The Industrial Source Complex— from chlorine production (and for four concentration modeled was 346 µg/m3, Short Term Dispersion Model, Version 3 sites, HCl production processes), which which is less than 6 percent of the (ISCST3), was used for this exposure ranged from less than one kilogram per AEGL2 1-hour threshold value for assessment. Receptors were placed at year to around 32 Mg/yr. chlorine (5,800 µg/m3). This highest 1- the center of census blocks (based on The hourly plantwide chlorine hour HCl modeled concentration was emissions from chlorine production the 2000 Census) within 2 kilometers of 120 µg/m3, which is less than 1 percent processes ranged from less than 2 grams the site and in the population-weighted of the AEGL2 1-hour threshold value for per hour (g/hr) to around 10 kilograms centers of census block groups or census HCl (33,000 µg/m3). We modeled these per hour (kg/hr). For the 11 sites tracks out to 50 kilometers. short-term concentrations for 5 years for reporting HCl emissions, the hourly HCl Meteorological data from the nearest each plant, which means concentrations emissions ranged from less than 1 g/hr representative meteorological station were obtained for over 830,000 hours. to around 1 kg/hr. were used. EPA requests comments on Ten of the plant sites did not report how to consider locations of receptors Only around 75 hours (less than one any fugitive emissions. We believe that in assessing potential impacts on an hundredth of one percent) had modeled it is reasonable to expect that all individual exposed at the upper end of chlorine concentrations greater than 5 chlorine production facilities would the exposure distribution for a large percent of the AEGL2 value, and no have some fugitive emissions. number of diverse facilities. hours had modeled HCl concentrations Therefore, we developed emission To determine the impacts of long-term greater than the AEGL2 value. factors based on the reported fugitive exposure to chlorine and HCl emissions Given the fact that the highest emissions and related capacities for from chlorine plants, we used the modeled concentrations were so far those plant sites that did report fugitive maximum annual emission values below the threshold values, we elected emissions. These factors ranged from 6.3 provided by the plants. As discussed to primarily evaluate the uncertainty × 10–¥8 to 2.88 pounds per ton of above, we converted the chlorine and variability of this assessment chlorine production capacity. We used emissions to HCl since chlorine only qualitatively, coupled with a few basic the maximum emission factor to persists in the atmosphere for a short sensitivity analyses. These sensitivity conservatively estimate fugitive amount of time. Therefore, we modeled analyses focused on evaluating the emissions for the 10 facilities that did the annual average HCl concentration at uncertainties for the ‘‘worst-case’’ not report fugitive emissions. each receptor that was the result of the situations, as we were not concerned The release characteristics needed for combination of the HCl emissions and with uncertainties that resulted in even the dispersion model included stack the chlorine emissions that were lower estimated risks. height, stack diameter, temperature, and converted to HCl through photolysis We identified four potential areas of exit velocity for point sources. For and subsequent reaction with methane. uncertainty/ variability in the exposure approximately 98 percent of the point As noted earlier, ten of the plants did assessment described above. These are sources reported, these parameters were not report any fugitive emissions. For emissions, the fate and transport model, provided in the section 114 responses. these plants, we modeled the reported exposure estimates, and toxicological If release characteristics were not point source emissions and then dose response. Each of these areas is provided, we assigned default modeled the estimated fugitive briefly discussed in the following. parameters based on data for the emissions separately. We added the As emission rates increase, exposure chlorine production industry in national highest concentration resulting from and risk increase. As noted earlier, the emission databases and other data point source emissions with the highest facilities reported maximum annual and reported in response to the survey. The concentration resulting from the fugitive maximum hourly emission rates. Most release characteristics needed for emissions to obtain a conservative often, the reported rates were the fugitive emission sources are release estimate of the highest HCl facility’s permitted emission rates. In height and area. Release heights were concentration that would be expected. addition, for those facilities that did not provided for about 17 percent of the The highest modeled annual average report any fugitive emissions, we fugitive emission sources. For those HCl concentration from any chlorine estimated and modeled fugitive fugitive emission sources for which production plant was 0.6 µg/m3. This is emissions based on the highest emission information on release heights were not less than 3 percent of the HCl RfC of 20 factor. Therefore, we would expect provided, we assumed that they were at µg/m3. Over 15 million people live in actual emissions to be less than those 1 meter. No information was provided the areas around these 19 plant sites. Of modeled, and thus, we believe that the regarding the area of the fugitive these people, only around 1,300 were results are biased high.

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The primary uncertainties identified discussed above, the factors that we magnification with toxic effects that are associated with the fate and believe could result in underestimated manifest at higher trophic levels. transport modeling were the inherent HAP concentrations (and, therefore, As discussed above, the evidence uncertainty associated with the trying to underestimated risks) include the available to date indicates that chlorine represent complex atmospheric default stack parameters for point and HCl are threshold pollutants for the processes with a series of equations in sources and the default size and purposes of section 112(d)(4). Since the ISCST3 model (which is beyond the location of the fugitive emission chlorine is converted to HCl in the scope of this assessment) and missing sources. atmosphere, we did not perform a release parameters, particularly for We conducted a worst-case analysis separate evaluation of chlorine exposure fugitive emission sources. for both long-term and short-term in this analysis. For the point sources, around 2 exposures to evaluate the potential No research has been identified for percent of the parameters were missing. upper-end impact of these uncertainties. effects on terrestrial animal species For each missing parameter, we For this analysis, we selected the single beyond that cited in the development of assigned a default parameter that was point source location from all plants the HCl RfC. Modeling calculations within the ranges provided by the other that resulted in the highest estimated indicate that there is little likelihood of respondents. Since the actual release concentration people would be exposed chronic or widespread exposure to HCl characteristics could be either higher or to when run using a uniform emission at concentrations above the threshold lower than these defaults, the results rate. We then modeled the highest total around chlorine production facilities. could be biased either way for this small facility emissions (maximum annual Based on these considerations, we percentage of the point sources. emissions for the long-term analysis and believe that the RfC can reasonably be Release heights were only provided maximum hourly emissions for the expected to protect against widespread for 17 percent of the fugitive emission short-term analysis) of chlorine and HCl adverse effects in other animal species sources, which ranged from 1.8 meters at that point source location and used as well. to 9.1 meters. For the fugitive sources the most conservative stack parameters. Plants also respond to airborne HCl without heights provided, we used a We then chose the highest of these totals levels. Chronic exposure to about 600 default height of 1 meter, which is more for chlorine and for HCl to put at the µg/m3 can be expected to result in conservative than any reported value. single point location. We also modeled discernible effects, depending on the Therefore, we anticipated that this a fugitive emission source using the plant species. Plants respond differently could bias the results high. highest reported emission factor to HCl as an anhydrous gas than to HCl There was considerable uncertainty coupled with the highest production aerosols. Relative humidity is important associated with the size and location of capacity. in plant response; there appears to be a fugitive emission sources. We used a The results of this analysis show that, threshold of relative humidity above default area of 2,000 m2 for every even with these worst-case conditions, which plants will incur twice as much fugitive emission source, with the modeled concentrations were well damage at a given dose. Effects include dimensions approximately 45 meters by below the threshold values. For the leaf injury and decrease in chlorophyll 45 meters. This is a generic default long-term impacts of the chlorine and levels in various species given acute, value that we typically use for modeling HCl emissions (modeled as HCl, as 20-minute exposures of 6,500 to 27,000 fugitive emission sources, and it is not discussed previously), the highest µg/m3. A field study reports different based on information provided by actual modeled annual HCl concentration was sensitivity to damage of foliage in 50 chlorine production facilities. The less than 5 µg/m3, which is less than 23 species growing in the vicinity of an southwest corner of this area was placed percent of the HCl RfC. The highest anhydrous aluminum chloride at the mid-point of the locations for all modeled maximum 1-hour chlorine and manufacturer. American elm, bur oak, reported point sources for the facility. HCl concentrations were around 2,500 eastern white pine, basswood, red ash The lack of information regarding the µg/m3 and 230 µg/m3, respectively. and several bean species were observed true size and location of chlorine These values represent around 44 to be most sensitive. Concentrations of production facilities could bias the percent of the 1-hour chlorine AEGL2 HCl in the air were not reported. concentration estimates high or low. threshold value and less than 1 percent Chloride ion in whole leaves was 0.2 to Uncertainty and variability also exist of the 1-hour HCl AEGL2. 0.5 percent of dry weight; sensitive in the exposure estimates and the species showed damage at the lower toxicological dose response, most of 3. Environmental Effects value, but tolerant species displayed no which result in the overestimation of The standards for emissions must also injury at the higher value. Injury risk. The RfC and AEGL2 values used in protect against significant and declined with distance from the source the assessment, which were discussed widespread adverse environmental with no effects observed beyond 300 above, may contain multiple uncertainty effects to wildlife, aquatic life, and other meters. Maximum modeled long-term factors whose impact is to add degrees natural resources. We did not conduct a HCl concentrations (0.6 µg/m3) are well of conservatism resulting in an formal ecological risk assessment. below the 600 µg/m3 chronic threshold, overestimation of noncancer effects. In However, we have reviewed and the maximum short-term HCl addition, the RfC assumes that publications in the literature to concentration (346 µg/m3) are far below individuals would be continuously determine if there would be reasonable the 6,500 µg/m3 acute exposure exposed to the modeled concentration. expectation for serious or widespread threshold. Therefore, no adverse As we believe these factors would only adverse effects to natural resources. exposure effects are anticipated. decrease the risk estimates, we did not We consider the following aspects of Prevailing meteorology strongly evaluate their impact. pollutant exposure and effects: Toxicity determines the fate of HCl in the As noted above, our focus was only effects from acute and chronic atmosphere. However, HCl is not on those uncertainties that might exposures to expected concentrations considered a strongly persistent increase the risk estimates and, thus, around the source (as measured or pollutant, or one where long range impact our decision not to regulate HCl modeled), persistence in the transport is important in predicting its and chlorine emissions from this source environment, local and long-range ecological effects. In the atmosphere, category. Of the basic uncertainties transport, and tendency for bio- HCl can be expected to be absorbed into

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aqueous aerosols, due to its great can be corrosive to tissue when above a chlorine and HCl emissions from affinity for water, and removed from the threshold concentration. The chloride chlorine production facilities are well troposphere by rainfall. In addition, HCl ions may be concentrated in some plant below the health threshold values. will react with hydroxy ions to yield tissues, but may be distributed Furthermore, the threshold values, for water plus chloride ions. However, the throughout the organism, as most which the RfC and AEGL values were concentration of hydroxy ions in the organisms have chloride ions in their determined to be appropriate values, troposphere is low, so HCl may have a fluids. Leaves or other tissues exposed were not exceeded when taking into relatively long residence time in areas of to HCl may show some concentration account an ample margin of safety. low humidity. No studies are reported above that of their immediate Finally, no significant or widespread of HCl levels in ponds or other small environment; that is, some degree of adverse environmental effects from water bodies or soils near major sources bioconcentration can occur. However, chlorine and HCl are anticipated. of HCl emissions. Toxic effects of HCl long-term storage in specific organs and Therefore, under authority of section to aquatic organisms would likely be biomagnification of concentrations of 112(d)(4), we have determined that due to the hydronium ion, or acidity. HCl in trophic levels of a food chain further control of chlorine and HCl Aquatic organisms in their natural would not be expected. Thus, the emissions from chlorine production environments often exhibit a broad chemical nature of HCl results in facilities is not necessary. range of pH tolerance. Effects of HCl deleterious effects, that when present, deposition to small water bodies and to are local rather than widespread. IV. Solicitation of Comments and Public soils will primarily depend on the In conclusion, acute and chronic Participation extent of neutralizing by carbonates or exposures to expected HCl and chlorine other buffering compounds. Chloride concentrations around the source are We seek full public participation in ions are essentially ubiquitous in not expected to result in adverse arriving at final decisions and encourage natural waters and soils so minor toxicity effects. These pollutants are not comments on all aspects of this notice increases due to deposition of dissolved persistent in the environment. Effects of of proposed action from all interested HCl will have much less effect than the HCl and chlorine on ponds and soils are parties. You need to submit appropriate deposited hydronium ions. Deleterious likely to be local rather than supporting data and analyses with your effects of HCl on ponds and soils, where widespread. Finally, chlorine and HCl comments to allow us to make the best such effects might be found near a major are not believed to result in use of them. Be sure to direct your source emitting to the atmosphere, biomagnification or bioaccumulation in comments to the Air and Radiation likely will be local rather than the environment. Therefore, we do not Docket and Information Center, Docket widespread, as observed in plant anticipate any adverse ecological effects No. A–2002–09 (see ADDRESSES). foliage. from chlorine and HCl. Dated: June 5, 2002. Effects of HCl on tissues are generally restricted to those immediately affected 4. Summary of Basis for Proposed Christine Todd Whitman, and are essentially acidic effects. The Action Administrator. rapid solubility of HCl in aqueous The results of the exposure [FR Doc. 02–15874 Filed 7–2–02; 8:45 am] media releases hydronium ions, which assessment showed exposure levels to BILLING CODE 6560–50–P

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