[Federal Register: March 24, 2008 (Volume 73, Number 57)] [Rules and Regulations] [Page 15603-15631] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr24mr08-14] [[Page 15603]] ----------------------------------------------------------------------- Part III Environmental Protection Agency ----------------------------------------------------------------------- 40 CFR Parts 51 and 59 National Volatile Organic Compound Emission Standards for Aerosol Coatings; Final Rule [[Page 15604]] ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 51 and 59 [EPA-HQ-OAR-2006-0971; FRL-8498-6] RIN 2060-AN69 National Volatile Organic Compound Emission Standards for Aerosol Coatings AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. ----------------------------------------------------------------------- SUMMARY: This action promulgates national emission standards for the aerosol coatings (aerosol spray paints) category under section 183(e) of the Clean Air Act (CAA). The standards implement section 183(e) of the CAA, as amended in 1990, which requires the Administrator to control volatile organic compounds (VOC) emissions from certain categories of consumer and commercial products for purposes of reducing VOC emissions contributing to ozone formation and ozone nonattainment. This regulation establishes nationwide reactivity-based standards for aerosol coatings. States have previously promulgated rules for the aerosol coatings category based upon reductions of VOC by mass; however, EPA has concluded that a national rule based upon the relative reactivity approach will achieve more reduction in ozone formation than may be achieved by a mass-based approach for this specific product category. This rule will better control a product's contribution to ozone formation by encouraging the use of less reactive VOC ingredients, rather than treating all VOC in a product alike through the traditional mass-based approach. We are also revising EPA's regulatory definition of VOC. This revision is necessary to include certain compounds that would otherwise be exempt in order to account for the reactive compounds in aerosol coatings that contribute to ozone formation. Therefore, certain compounds that would not be VOC under the otherwise applicable definition will count towards the applicable reactivity limits under this final regulation. The initial listing of product categories and schedule for regulation was published on March 23, 1995 (60 FR 15264). This final action announces EPA's final decision to list aerosol coatings for regulation under Group III of the consumer and commercial product category for which regulations are mandated under section 183(e) of the CAA. DATES: Effective Date: This final rule is effective March 24, 2008. The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of March 24, 2008. ADDRESSES: EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2006-0971. All documents in the docket are listed on the www.regulations.gov Web site. Although listed in the index, some information is not publicly available (e.g., Confidential Business Information (CBI) or other information whose disclosure is restricted by statute). Certain other material, such as copyrighted material, will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through www.regulations.gov or in hard copy at the EPA Docket Center, Docket ID No. EPA-HQ-OAR-2006-0971, EPA Headquarters Library, Room 3334 in the EPA West Building, 1301 Constitution Ave., NW., Washington, DC. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The EPA Docket Center telephone number is (202) 566-1744, and the facsimile number for the EPA Docket Center is (202) 566-9744. EPA visitors are required to show photographic identification and sign the EPA visitor log. After processing through the X-ray and magnetometer machines, visitors will be given an EPA/DC badge that must be visible at all times. Informational updates will be provided via the EPA Web site at http://www.epa.gov/epahome/dockets.htm as they are available. FOR FURTHER INFORMATION CONTACT: For questions about the final rule, contact Ms. J. Kaye Whitfield, U.S. EPA, Office of Air Quality Planning and Standards, Sector Policies and Programs Division, Natural Resources and Commerce Group (E143-03), Research Triangle Park, NC 27711; telephone number (919) 541-2509; facsimile number (919) 541-3470; e- mail address: whitfield.kaye@epa.gov. For information concerning the CAA section 183(e) consumer and commercial products program, contact Mr. Bruce Moore, U.S. EPA, Office of Air Quality Planning and Standards, Sector Policies and Programs Division, Natural Resources and Commerce Group (E143-03), Research Triangle Park, North Carolina 27711, telephone number: (919) 541-5460, facsimile number (919) 541-3470, e- mail address: moore.bruce@epa.gov. SUPPLEMENTARY INFORMATION: Entities Potentially Affected by This Action. The entities potentially affected by this regulation encompass all steps in aerosol coatings operations. This includes manufacturers, processors, wholesale distributors, or importers of aerosol coatings for sale or distribution in the United States, or manufacturers, processors, wholesale distributors, or importers who supply the entities listed above with aerosol coatings for sale or distribution in interstate commerce in the United States. The entities potentially affected by this action include: ------------------------------------------------------------------------ NAICS code Examples of regulated Category \a\ entities ------------------------------------------------------------------------ Paint and Coating Manufacturing.. 32551 Manufacturing of lacquers, varnishes, enamels, epoxy coatings, oil and alkyd vehicle, plastisols, polyurethane, primers, shellacs, stains, water repellant coatings. All Other Miscellaneous Chemical 325998 Aerosol can filling, Production and Preparation aerosol packaging Manufacturing. services. ------------------------------------------------------------------------ \a\ North American Industry Classification System http://www.census.gov/ epcd/www/naics.html. This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. To determine whether you would be affected by this action, you should examine the applicable industry description in section I.E of the promulgation preamble. If you have any questions regarding the applicability of this action to a particular entity, consult the appropriate EPA contact listed in the FOR FURTHER INFORMATION CONTACT section of this notice. Docket. The docket number for the National Volatile Organic Compounds Emission Standards for Aerosols Coating (40 CFR part 59, subpart E) is Docket ID No. EPA-HQ-OAR-2006-0971. [[Page 15605]] World Wide Web (WWW). In addition to being available in the docket, an electronic copy of the final rule is also available on the WWW. Following the Administrator's signature, a copy of the final rule will be posted on EPA's Technology Transfer Network (TTN) policy and guidance page for newly proposed or promulgated rules at http:// www.epa.gov/ttn/oarpg. The TTN provides information and technology exchange in various areas of air pollution control. Judicial Review. Under section 307(b)(1) of the Clean Air Act (CAA), judicial review of the final rule is available only by filing a petition for review in the U.S. Court of Appeals for the District of Columbia Circuit by May 23, 2008. Under CAA section 307(b)(2), the requirements established by this final action may not be challenged separately in any civil or criminal proceedings brought by EPA to enforce these requirements. Section 307(d)(7)(B) of the CAA further provides that ``only an objection to a rule or procedure which was raised with reasonable specificity during the period for public comment (including any public hearing) may be raised during judicial review.'' This section also provides a mechanism for EPA to convene a proceeding for reconsideration, ``if the person raising the objection can demonstrate to EPA that it was impracticable to raise such an objection [within the period for public comment] or if the grounds for such objection arose after the period for public comment (but within the time specified for judicial review) and if such objection is of central relevance to the outcome of the rule.'' Any person seeking to make such a demonstration to EPA should submit a Petition for Reconsideration to the Office of the Administrator, U.S. EPA, Room 3000, Ariel Rios Building, 1200 Pennsylvania Ave., NW., Washington, DC 20460, with a copy to both the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT section, and the Air and Radiation Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave., NW., Washington, DC 20004. Organization of This Document. The information presented in this notice is organized as follows: I. Background A. The Ozone Problem B. Statutory and Regulatory Background C. Photochemical Reactivity D. Role of Reactivity in VOC/Ozone Regulations E. The Aerosol Coating Industry II. Summary of the Final Standards and Changes Since Proposal A. Applicability of the Standards and Regulated Entities B. VOC Regulated Under This Rule C. Regulatory Limits D. Compliance Dates E. Labeling Requirements F. Recordkeeping and Reporting G. Variance H. Test Methods III. Response to Significant Comments A. Format of Regulation B. Downwind Effects and Robustness of Relative Reactivity Scale C. Consideration of Other Factors in the Consideration of Best Available Control D. Variance, Small Quantity Manufacturers and Extended Compliance Date E. Additional Reporting Requirements IV. Summary of Impacts A. Environmental Impacts B. Energy Impacts C. Cost and Economic Impacts V. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Act D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution or Use I. National Technology Transfer and Advancement Act J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations K. Congressional Review Act I. Background A. The Ozone Problem Ground-level ozone, a major component of smog, is formed in the atmosphere by reactions of VOC and oxides of nitrogen in the presence of sunlight. The formation of ground-level ozone is a complex process that is affected by many variables. Exposure to ground-level ozone is associated with a wide variety of human health effects, as well as agricultural crop loss, and damage to forests and ecosystems. Controlled human exposure studies show that acute health effects are induced by short-term (1 to 2 hour) exposures (observed at concentrations as low as 0.12 parts per million (ppm)), generally while individuals are engaged in moderate or heavy exertion, and by prolonged (6 to 8 hour) exposures to ozone (observed at concentrations as low as 0.08 ppm and possibly lower), typically while individuals are engaged in moderate exertion. Transient effects from acute exposures include pulmonary inflammation, respiratory symptoms, effects on exercise performance, and increased airway responsiveness. Epidemiological studies have shown associations between ambient ozone levels and increased susceptibility to respiratory infection, increased hospital admissions and emergency room visits. Groups at increased risk of experiencing elevated exposures include active children, outdoor workers, and others who regularly engage in outdoor activities. Those most susceptible to the effects of ozone include those with pre- existing respiratory disease, children, and older adults. The literature suggests the possibility that long-term exposures to ozone may cause chronic health effects (e.g., structural damage to lung tissue and accelerated decline in baseline lung function). B. Statutory and Regulatory Background Under section 183(e) of the CAA, EPA conducted a study of VOC emissions from the use of consumer and commercial products to assess their potential to contribute to levels of ozone that violate the National Ambient Air Quality Standards (NAAQS) for ozone, and to establish criteria for regulating VOC emissions from these products. Section 183(e) of the CAA directed EPA to list for regulation those categories of products that account for at least 80 percent of the VOC emissions, on a reactivity-adjusted basis, from consumer and commercial products in areas that violate the NAAQS for ozone (i.e., ozone nonattainment areas), and to divide the list of categories to be regulated into four groups. EPA published the initial list in the Federal Register on March 23, 1995 (60 FR 15264). In that notice, EPA stated that it may amend the list of products for regulation, and the groups of product categories listed for regulation, in order to achieve an effective regulatory program in accordance with EPA's discretion under CAA section 183(e). EPA has revised the list several times. Most recently, in May 2006, EPA revised the list to add one product category, portable fuel containers, and to remove one product category, petroleum dry cleaning solvents. See 71 FR 28320 (May 16, 2006). The aerosol spray paints (aerosol coatings) category currently is listed for regulation as part of Group III of the CAA section 183(e) list. CAA section 183(e) directs EPA to regulate consumer and commercial products using ``best available controls'' (BAC). CAA section 183(e)(1)(A) defines BAC as ``the degree of emissions reduction that the Administrator [[Page 15606]] determines, on the basis of technological and economic feasibility, health, environmental, and energy impacts, is achievable through the application of the most effective equipment, measures, processes, methods, systems or techniques, including chemical reformulation, product or feedstock substitution, repackaging, and directions for use, consumption, storage, or disposal.'' CAA section 183(e) also provides EPA with authority to use any system or systems of regulation that EPA determines is the most appropriate for the product category. Under CAA section 183(e)(4), EPA can impose ``any system or systems of regulation as the Administrator deems appropriate, including requirements for registration and labeling, self-monitoring and reporting, prohibitions, limitations, or economic incentives (including marketable permits and auctions of emissions rights) concerning the manufacture, processing, distribution, use, consumption or disposal of the product.'' Under these provisions, EPA has previously issued national regulations for architectural coatings, autobody refinishing coatings, consumer products, and portable fuel containers.\1\ \2\ \3\ \4\ \5\ --------------------------------------------------------------------------- \1\ ``National Volatile Organic Compound Emission Standards for Architectural Coatings'' 63 FR 48848, (September 11, 1998). \2\ ``National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings'' 63 FR 48806, (September 11, 1998). \3\ ``Consumer and Commercial Products: Schedule for Regulation'' 63 FR 48792, (September 11, 1998) \4\ National Volatile Organic Compound Emission Standards for Consumer Products'' 63 FR 48819, (September 11, 1998). \5\ ``National Volatile Organic Compound Emission Standards for Portable Fuel Containers'' 72 FR 8428, (February 26, 2007). --------------------------------------------------------------------------- For any category of consumer or commercial products, the Administrator may issue control techniques guidelines (CTG) in lieu of national regulations if the Administrator determines that such guidance will be substantially as effective as a national regulation in reducing emissions of VOC which contribute to ozone levels in areas which violate the NAAQS for ozone. In many cases, a CTG can be an effective regulatory approach to reduce emissions of VOC in nonattainment areas because of the nature of the specific product and the uses of such product. A critical distinction between a national rule and a CTG is that a CTG may include provisions that affect the users of the products. For other product categories, such as wood furniture coatings and shipbuilding coatings, EPA has previously determined that, under CAA section 183(e)(3)(C), a CTG would be substantially as effective as a national rule and, therefore, issued CTGs to provide guidance to States for development of appropriate State regulations. Most recently, EPA determined that a CTG would be substantially as effective as a national rule for three other Group III categories: Paper, Film and Foil Coating; Metal Furniture Coating; and Large Appliance Coating.\6\ --------------------------------------------------------------------------- \6\ ``Consumer and Commercial Products: Control Techniques Guidelines in Lieu of Regulations for Paper, Film, and Foil Coatings; Metal Furniture Coatings; and Large Appliance Coatings'' 72 FR 57215, (October 9, 2007). --------------------------------------------------------------------------- For the category of aerosol coatings, EPA has determined that a national rule applicable nationwide is the best system of regulation to achieve necessary VOC emission reductions from this type of product. Aerosol coatings are typically used in relatively small amounts by consumers and others on an occasional basis and at varying times and locations. Under such circumstances, reformulation of the VOC content of the products is a more feasible way to achieve VOC emission reductions, rather than through a CTG approach that would only affect a smaller number of relatively large users. Aerosol coatings regulations are already in place in three States (California, Oregon, and Washington), and other States are considering developing regulations for these products. For the companies that market aerosol coatings in different States, trying to fulfill the differing requirements of State rules may create administrative, technical, and marketing problems. Although Section 183(e) does not preempt States from having more stringent State standards, EPA's national rule is expected to provide some degree of consistency, predictability, and administrative ease for the industry. A national rule also helps States reduce potential compliance problems associated with noncompliant coatings being transported into nonattainment areas from neighboring areas and neighboring States. A national rule will also enable States to obtain needed VOC emission reductions from this sector in the near term, without having to expend their limited resources to develop similar rules in each State.\7\ --------------------------------------------------------------------------- \7\ Courts have already approved EPA's creation of national rules under section 183(e). See, ALARM Caucus v. EPA, 215 F.3d 61,76 (D.C. Cir. 2000), cert. denied, 532 U.S. 1018 (2001). --------------------------------------------------------------------------- C. Photochemical Reactivity There are thousands of individual species of VOC that can participate in a series of reactions involving nitrogen oxides (NOX) and the energy from sunlight, resulting in the formation of ozone. The impact of a given species of VOC on formation of ground-level ozone is sometimes referred to as its ``reactivity.'' It is generally understood that not all VOC are equal in their effects on ground-level ozone formation. Some VOC react extremely slowly and changes in their emissions have limited effects on ozone pollution episodes. Some VOC form ozone more quickly than other VOC, or they may form more ozone than other VOC. Other VOC not only form ozone themselves, but also act as catalysts and enhance ozone formation from other VOC. By distinguishing between more reactive and less reactive VOC, however, EPA concludes that it may be possible to develop regulations that will decrease ozone concentrations further or more efficiently than by controlling all VOC equally. Assigning a value to the reactivity of a specific VOC species is a complex undertaking. Reactivity is not simply a property of the compound itself; it is a property of both the compound and the environment in which the compound is found. Therefore, the reactivity of a specific VOC varies with VOC:NOX ratios, meteorological conditions, the mix of other VOC in the atmosphere, and the time interval of interest. Designing an effective regulation that takes account of these interactions is difficult. Implementing and enforcing such a regulation requires an extra burden for both industry and regulators, as those impacted by the rule must characterize and track the full chemical composition of VOC emissions rather than only having to track total VOC content as is required by traditional mass-based rules. EPA's September 13, 2005, final rule approving a comparable reactivity-based aerosol coating rule as part of the California State Implementation Plan for ozone contains additional background information on photochemical reactivity.\8\ Recently, EPA issued interim guidance to States regarding the use of VOC reactivity information in the development of ozone control measures.\9\ --------------------------------------------------------------------------- \8\ ``Revisions to the California State Implementation Plan and Revision to the Definition of Volatile Organic Compounds (VOC)- Removal of VOC Exemptions for California's Aerosol Coating Products Reactivity-based Regulation'' 70 FR 53930, (September 13, 2005). \9\ ``Interim Guidance on Control of Volatile Organic Compounds in Ozone State Implementation Plans'') 70 FR 54046, (September 13, 2005). --------------------------------------------------------------------------- 1. What Research Has Been Conducted on VOC Reactivity? Much of the initial work on reactivity scales was funded by the California Air [[Page 15607]] Resources Board (CARB), which was interested in comparing the reactivity of emissions from different alternative fuel vehicles. In the late 1980s, CARB provided funding to William P. L. Carter at the University of California to develop a reactivity scale. Carter investigated 18 different methods of ranking the reactivity of individual VOC in the atmosphere using a single-cell trajectory model with a state-of-the-art chemical reaction mechanism.\10\ Carter suggested three scales for further consideration: --------------------------------------------------------------------------- \10\ Carter, W. P. L. (1994) ``Development of ozone reactivity scales for organic gases,'' J. Air Waste Manage. Assoc., 44: 881- 899. --------------------------------------------------------------------------- i. Maximum Incremental Reactivity (MIR) scale--an ozone yield scale derived by adjusting the NOX emissions in a base case to yield the highest incremental reactivity of the base reactive organic gas mixture. ii. Maximum Ozone Incremental Reactivity (MOIR) scale--an ozone yield scale derived by adjusting the NOX emission in a base case to yield the highest peak ozone concentration. iii. Equal Benefit Incremental Reactivity (EBIR) scale--an ozone yield scale derived by adjusting the NOX emissions in a base case scenario so VOC and NOX reductions are equally effective in reducing ozone. Carter concluded that, if only one scale is used for regulatory purposes, the MIR scale is the most appropriate.\11\ The MIR scale is defined in terms of environmental conditions where ozone production is most sensitive to changes in hydrocarbon emissions and, therefore, represents conditions where hydrocarbon controls would be the most effective. CARB used the MIR scale to establish fuel-neutral VOC emissions limits in its low-emitting vehicle and alternative fuels regulation.\12\ \13\ Subsequently, Carter has updated the MIR scale several times as the chemical mechanisms in the model used to derive the scale have evolved with new scientific information. CARB incorporated a 1999 version of the MIR scale in its own aerosol coatings rule. The latest revision to the MIR scale was issued in 2003. --------------------------------------------------------------------------- \11\ ``Initial Statement of Reasons for the California Aerosol Coatings Regulation, California Air Resources Board,'' 2000. \12\ California Air Resources Board ``Proposed Regulations for Low-Emission Vehicles and Clean Fuels--Staff Report and Technical Support Document,'' State of California, Air Resources Board, P.O. Box 2815, Sacramento, CA 95812, August 13, 1990. \13\ California Air Resources Board ``Proposed Regulations for Low-Emission Vehicles and Clean Fuels--Final Statement of Reasons,'' State of California, Air Resources Board, July 1991. --------------------------------------------------------------------------- In addition to Carter's work, there have been other attempts to create reactivity scales. One such effort is the work of R.G. Derwent and co-workers, who have published articles on a scale called the photochemical ozone creation potential (POCP) scale.\14\ \15\ This scale was designed for the emissions and meteorological conditions prevalent in Europe. The POCP scale is generally consistent with that of Carter, although there are some differences because it uses a different model, chemical mechanism, and emission and meteorological scenarios. Despite these differences, there is a good correlation of r\2\=0.9 between the results of the POCP and the MIR scales.\16\ --------------------------------------------------------------------------- \14\ Derwent, R.G., M.E. Jenkin, S.M. Saunders and M.J. Pilling (2001) ``Characterization of the Reactivities of Volatile Organic Compounds Using a Master Chemical Mechanism,'' J. Air Waste Management Assoc., 51: 699-707. \15\ Derwent, R.G., M.E. Jenkin, S.M. Saunders and M.J. Pilling (1998) ``Photochemical Ozone Creation Potentials for Organic Compounds in Northwest Europe Calculated with a Master Chemical Mechanism,'' Atmos. Env., 32(14/15):2429-2441. \16\ See http://www.narsto.org/section.src?SID=10. --------------------------------------------------------------------------- As CARB worked to develop reactivity-based regulations in California, EPA began to explore the implications of applying reactivity scales in other parts of the country. In developing its regulations, CARB has maintained that the MIR scale is the most appropriate metric for application in California, but cautioned that its research has focused on California atmospheric conditions and that the suitability of the MIR scale for regulatory purposes in other areas has not been demonstrated. In particular, specific concerns have been raised about the suitability of using the MIR scale in relation to multi-day stagnation or transport scenarios or over geographic regions with very different VOC:NOX ratios than those of California. In 1998, EPA participated in the formation of the Reactivity Research Working Group (RRWG), which was organized to help develop an improved scientific basis for reactivity-related regulatory policies.\16\ All interested parties were invited to participate. Since that time, representatives from EPA, CARB, Environment Canada, States, academia, and industry have met in public RRWG meetings to discuss and coordinate research that would support this goal. The RRWG has organized a series of research efforts to explore: i. The sensitivity of ozone to VOC mass reductions and changes in VOC composition under a variety of environmental conditions; ii. The derivation and evaluation of reactivity scales using photochemical airshed models under a variety of environmental conditions; iii. The development of emissions inventory processing tools for exploring reactivity-based strategies; and iv. The fate of VOC emissions and their availability for atmospheric reactions. This research has led to a number of findings that increase EPA's confidence in the ability to develop regulatory approaches that differentiate between specific VOC on the basis of relative reactivity. The first two research objectives listed above were explored in a series of three parallel modeling studies that resulted in four reports and one journal article.\17\ \18\ \19\ \20\ \21\ EPA commissioned a review of these reports to address a series of policy-relevant science questions.\22\ In 2007, an additional peer review was commissioned by EPA to assess the appropriateness of basing a national aerosol coatings regulation on reactivity. Generally, the peer reviews support the appropriateness of the use of the box-model based MIR metric nationwide for the aerosol coatings category. The results are available in the rulemaking docket. --------------------------------------------------------------------------- \17\ Carter, W.P.L., G. Tonnesen, and G. Yarwood (2003) Investigation of VOC Reactivity Effects Using Existing Regional Air Quality Models, Report to American Chemistry Council, Contract SC- 20.0-UCR-VOC-RRWG, April 17, 2003. \18\ Hakami, A., M.S. Bergin, and A.G. Russell (2003) Assessment of the Ozone and Aerosol Formation Potentials (Reactivities) of Organic Compounds over the Eastern United States, Final Report, Prepared for California Air Resources Board, Contract No. 00-339, January 2003. \19\ Hakami, A., M.S. Bergin, and A.G. Russell (2004a) Ozone Formation Potential of Organic Compounds in the Eastern United States: A Comparison of Episodes, Inventories, and Domains, Environ. Sci. Technol. 2004, 38, 6748-6759. \20\ Hakami, A., M. Arhami, and A.G. Russell (2004b) Further Analysis of VOC Reactivity Metrics and Scales, Final Report to the U.S. EPA, Contract 4D-5751-NAEX, July 2004. \21\ Arunachalam S., R. Mathur, A. Holland, M.R. Lee, D. Olerud, Jr., and H. Jeffries (2003) Investigation of VOC Reactivity Assessment with Comprehensive Air Quality Modeling, Prepared for U.S. EPA, GSA Contract GS-35F-0067K, Task Order ID: 4TCG68022755, June 2003. \22\ Derwent, R.G. (2004) Evaluation and Characterization of Reactivity Metrics, Final Draft, Report to the U.S. EPA, Order No. 4D-5844-NATX, November 2004. --------------------------------------------------------------------------- The results of the RRWG-organized study and the subsequent reviews suggest that there is good correlation between different relative reactivity metrics calculated with photochemical airshed models, regardless of the choice of model, model domain, scenario, or averaging times. Moreover, the scales calculated with photochemical airshed models correlate relatively well with the MIR metric derived with a single cell, one-dimensional box model. Prior to the [[Page 15608]] RRWG-organized studies, little analysis of the robustness of the box- model derived MIR metric and its applicability to environmental conditions outside California had been conducted. Although these studies were not specifically designed to test the robustness of the box-model derived MIR metrics, the results suggest that the MIR metric is relatively robust. D. Role of Reactivity in VOC/Ozone Regulations Historically, EPA's general approach to regulation of VOC emissions has been based upon control of total VOC by mass, without distinguishing between individual species of VOC. EPA considered the regulation of VOC by mass to be the most effective and practical approach based upon the scientific and technical information available when EPA developed its VOC control policy. EPA issued the first version of its VOC control policy in 1971, as part of EPA's State Implementation Plan (SIP) preparation guidance.\23\ In that guidance, EPA emphasized the need to reduce the total mass of VOC emissions, but also suggested that substitution of one compound for another might be useful when it would result in a clearly evident decrease in reactivity and thus tend to reduce photochemical oxidant formation. This latter statement encouraged States to promulgate SIPs with VOC emission substitution provisions similar to the Los Angeles County Air Pollution Control District's (LACAPCD) Rule 66, which allowed some VOC that were believed to have low to moderate reactivity to be exempted from control. The exempt status of many of those VOC was questioned a few years later, when research results indicated that, although some of those compounds do not produce much ozone close to the source, they may produce significant amounts of ozone after they are transported downwind from urban areas. --------------------------------------------------------------------------- \23\ ``Requirements for Preparation, Adoption and Submittal of Implementation Plans'', Appendix B, 36 FR 15495, (August 14, 1971). --------------------------------------------------------------------------- In 1977, further research led EPA to issue a revised VOC policy under the title ``Recommended Policy on Control of Volatile Organic Compounds,'' (42 FR 35314, July 8, 1977), offering its own, more limited, list of exempt organic compounds. The 1977 policy identified four compounds that have very low photochemical reactivity and determined that their contribution to ozone formation and accumulation could be considered negligible. The policy exempted these ``negligibly reactive'' compounds from VOC emissions limitations in programs designed to meet the ozone NAAQS. Since 1977, EPA has added other compounds to the list of negligibly reactive compounds based on new information as it has been developed. In 1992, EPA adopted a formal regulatory definition of VOC for use in SIPs, which explicitly excludes compounds that have been identified as negligibly reactive [40 CFR 51.100(s)]. To date, EPA has exempted 54 compounds or classes of compounds in this manner. In effect, EPA's current VOC exemption policy has generally resulted in a two bin system in which most compounds are treated equally as VOC, and are controlled. A separate smaller group of compounds are treated as negligibly reactive, and are exempt from VOC controls.\24\ This approach was intended to encourage the reduction of emissions of all VOC that participate in ozone formation. From one perspective, it appears that this approach has been relatively successful. EPA estimates that, between 1970 and 2003, VOC emissions from man-made sources nationwide declined by 54 percent. This decline in VOC emissions has helped to decrease average ozone concentration by 29 percent (based on 1-hour averages) and 21 percent (based on 8-hour averages) between 1980 and 2003. These reductions occurred even though, between 1970 and 2003, population, vehicle miles traveled, and gross domestic product rose 39 percent, 155 percent and 176 percent, respectively.\25\ --------------------------------------------------------------------------- \24\ For some analytical purposes, EPA has distinguished between VOC and ``highly reactive'' VOC, such as in the EPA's initial evaluation of consumer products for regulation. See, ``Final Listing,'' 63 FR 48792, 48795-6 (Sept. 11, 1998) (explaining EPA's approach); see also, ALARM Caucus v. EPA, 215 F. 3d 61, 69-73 (D. C. Cir. 2000), cert. denied, 532 U.S. 1018 (2001) (approving EPA's approach as meeting the requirements of CAA section 183(e)). \25\ ``Latest Findings on National Air Quality: 2002 Status and Trends,'' EPA 454/K-03-001, (August 2003); and ``The Ozone Report Measuring Progress through 2003,'' EPA 454/K-04-001, (April 2004); Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. --------------------------------------------------------------------------- On the other hand, some have argued that a reactivity-based approach for reducing VOC emissions would be more effective than the current mass-based approach. One group of researchers conducted a detailed modeling study of the Los Angeles area and concluded that, compared to the current approach, a reactivity-based approach could achieve the same reductions in ozone concentrations at significantly less cost or, for a given cost, could achieve a significantly greater reduction in ozone concentrations.\26\ The traditional approach to VOC control that focused on reducing the overall mass of emissions may be adequate in some areas of the country. However, EPA's recent SIP guidance recognizes that approaches to VOC control that differentiate between VOC based on relative reactivity are likely to be more effective and efficient under certain circumstances.\27\ In particular, reactivity-based approaches are likely to be important in areas for which aggressive VOC control is a key strategy for reducing ozone concentrations. Such areas include: --------------------------------------------------------------------------- \26\ A. Russell, J. Milford, M. S. Bergin, S. McBride, L. McNair, Y. Yang, W. R. Stockwell, B. Croes, ``Urban Ozone Control and Atmospheric Reactivity of Organic Gases,'' Science, 269: 491- 495, (1995). \27\ ``Interim Guidance on Control of Volatile Organic Compounds in Ozone State Implementation Plans,'' 70 FR 54046, September 13, 2005). --------------------------------------------------------------------------- Areas with persistent ozone nonattainment problems; Urbanized or other NOX-rich areas where ozone formation is particularly sensitive to changes in VOC emissions; Areas that have already implemented VOC reasonably available control technology (RACT) measures and need additional VOC emission reductions. In these areas, there are a variety of possible ways of addressing VOC reactivity in the SIP development process, including: Developing accurate, speciated VOC emissions inventories. Prioritizing control measures using reactivity metrics. Targeting emissions of highly-reactive VOC compounds with specific control measures. Encouraging VOC substitution and composition changes using reactivity-weighted emission limits. The CARB aerosol coatings rule is an example of this last application of the concept of reactivity. CARB's reactivity-based rule for aerosol coatings was designed to encourage the use of compounds that are less effective at producing ozone. It contains limits for aerosol coatings expressed as grams of ozone formed per gram of product instead of the more traditional limits expressed as percent VOC by mass. EPA approved CARB's aerosol coatings rule as part of the California SIP for ozone. EPA's national aerosol coatings rule builds largely upon CARB's efforts to regulate this product category using the relative reactivity approach. E. The Aerosol Coating Industry Aerosol coatings include all coatings that are specially formulated and [[Page 15609]] packaged for use in pressurized cans. They are used by both professional and do-it-yourself (DIY) consumers. The DIY segment accounts for approximately 80 percent of all sales. The remainder of aerosol coatings is sold for industrial maintenance and original equipment manufacturer use. Aerosol coatings are used for a number of applications including small domestic coating jobs, field and construction site marking, and touch-up of marks and scratches in paintwork of automobiles, appliances and machinery. The aerosol coatings industry includes the formulators and manufacturers of the concentrated product. These manufacturers may package the product or they may use toll fillers (processors). These toll fillers may work not only with the large manufacturers, but for other coating manufacturers who do not have the specialized equipment necessary to fill aerosol containers. The fillers may then supply the product to coating dealers, home supply stores, distributors, company- owned stores and industrial customers. An aerosol consists of a gas in which liquid or solid substances may be dispensed. Aerosol coatings are pressurized coatings that, like other coatings, consist of pigments and resins and solvents. However, aerosol coatings also contain a propellant that dispenses the product ingredients. A controlled amount of propellant in the product vaporizes as it leaves the container, creating the aerosol spray. The combination of product and propellant is finely tuned to produce the correct concentration and spray pattern for an effective product. Aerosol coatings can be packaged in disposable cans for hand-held applications or for use in specialized equipment in ground traffic/ marking applications. As with other coatings, aerosol coatings are available in both solvent-based and water-based formulations. In developing the final national rule for aerosol coatings, EPA has used the same coating categories, and the same definitions for those categories, previously identified by CARB in its comparable regulation for aerosol coatings. We believe these categories adequately categorize the industry and encompass the range of products included in our own analysis of this category that we conducted in preparing EPA's Report to Congress (EPA-453/R-94-066-A). Use of the same definitions and categories has the added benefit of providing regulated entities with consistency between the CARB and national rules. The categories of aerosol coatings regulated in the final rule include six general categories and 30 specialty categories. Based on a survey of aerosol coating manufacturers conducted by CARB in 1997, VOC emissions from the six general categories together with the specialty category of Ground Traffic/Marking Coatings account for approximately 85 percent of the ozone formed as a result of the use of aerosol coatings. These categories are defined in this regulation and are described in more detail in the docket to this rulemaking. There are currently no national regulations addressing VOC emissions from aerosol coatings. California, Oregon and Washington are the only States that currently regulate aerosol coating products and Oregon's and Washington's rules are identical to the Tier 1 VOC mass- based limits developed by CARB that became effective in 1996. Unlike other EPA or State regulations and previous CARB regulations for aerosol coatings that regulate VOC ingredients by mass in the traditional approach, the current California regulation for aerosol coatings is designed to limit the ozone formed from VOC emissions from aerosol coatings by establishing limits on the reactivity of the cumulative VOC ingredients of such coatings. II. Summary of the Final Standards and Changes Since Proposal This section presents a summary of the major features of the final rule, as well as a summary of the changes made to the proposed rule. The reasons for the changes in the final rule are explained in Section III. A. Applicability of the Standards and Regulated Entities The final Aerosol Coatings Reactivity Rule (ACRR) will apply to manufacturers, processors, wholesale distributors, or importers of aerosol coatings used by both the general population (i.e., the ``Do It Yourself'' market) and industrial applications (e.g., at original equipment manufacturers and other industrial sites). This regulation will apply to distributors, if the name of the distributor appears on the label of the aerosol products. The final rule includes an exemption from the limits in Table 1 of the rule for those manufacturers that make a small annual volume of aerosol coating products, i.e., with a total VOC content by mass of no more than 7,500 kilograms of VOC per year in the aggregate for all aerosol coating products. EPA notes that an exemption under EPA's national rule for aerosol coatings under section 183(e) does not alter any requirements under any applicable State or local regulations. The regulatory language in this final rule has been changed from the proposed rule to clarify the regulated entity that is responsible for compliance with each portion of the regulation. The final rule includes a provision in section 59.501(f) that allows foreign manufacturers to qualify for the small quantity manufacturer exemption in section 59.501(e). Although foreign manufacturers are not regulated entities under this rule, some may choose to voluntarily become regulated entities in order to qualify for the small quantity manufacturer exemption. To qualify, the foreign manufacturer must (1) meet the same 7500 kilogram per year VOC mass limit that domestic small volume manufacturers must meet; (2) comply with the same recordkeeping and reporting requirements that domestic manufacturers must fulfill; and (3) comply with certain provisions in 40 CFR 59.501(f)(3), which are similar to those used in other EPA rules to ensure that EPA may effectively monitor and implement this rule with respect to foreign entities.\28\ --------------------------------------------------------------------------- \28\ See Regulation of Fuels and Fuel Additives: Baseline Requirements for Gasoline Produced by Foreign Refiners, Final Rule, 62 FR 45,533, 45,537-38 (August 28, 1997). --------------------------------------------------------------------------- B. VOC Regulated Under This Rule This rule regulates emissions of VOC from aerosol coatings. Because even less reactive VOC contribute to ozone formation, we are amending the regulatory definition of VOC for purposes of this rule by adding 40 CFR 51.100(s)(7). As provided in that new subsection, any organic compound in the volatile portion of an aerosol coating is counted towards the product's reactivity-based limit if it: (1) Has a reactivity factor (RF) value greater than that of ethane (0.3), or (2) is used in amounts greater than 7.3 percent of the product weight in the product formulation. Table 2A currently includes those organic compounds we know to be used in aerosol coatings that have an RF value greater than that of ethane (0.3). Under the proposed rule, we had a single de minimis threshold that provided that a compound would not be counted towards the applicable limit, regardless of its reactivity, if the compound represented less than 0.1 percent of the product weight. In the final rule, we have provided a two-part threshold: (1) A 0.1 percent threshold for compounds with an RF value greater than 0.3; and (2) a 7.3 percent threshold [[Page 15610]] for compounds with an RF value of 0.3 or less. The rationale for the 7.3 percent threshold is that compounds with an RF value of 0.3 or less will contribute minimally to ozone formation from this product category. We calculated the 7.3 percent figure as follows. We first determined the maximum RF value for a compound, which is 22.04 (the default value for compounds of unknown reactivity). We then multiplied that value by 0.1(the proposed percentage threshold for all organic compounds irrespective of their RF value), which resulted in a value of 2.2. To determine an appropriate percentage threshold for organic compounds with an RF value of 0.3 or less, we then divided 2.2 by 0.3 (the RF for ethane) which resulted in the 7.3 percent threshold for such compounds. Therefore, in determining compliance with the limits of this rule, this rule does not require inclusion of de minimis amounts of ingredients taking into consideration the relative reactivity of the compound. As provided in 40 CFR 59.505(e)(2), if in the future, compounds with an RF value of 0.3 or less are used in amounts greater than or equal to 7.3 percent of a particular aerosol coatings product formulation, then those compounds will be counted towards the applicable limits of this rule at that time. The emission limits in the rule are expressed in terms of weight of ozone generated from the VOC ingredients per weight of coating material, rather than the traditional weight of VOC ingredients per weight (or volume) of product. EPA has concluded that this approach will reduce the overall amount of ozone that results from the VOC emitted to the atmosphere from these products, while providing regulated entities with greater flexibility to select VOC ingredients for their products. This approach provides incentives to regulated entities to use VOC ingredients that have lower reactivity and that will therefore generate less ozone. EPA has revised the list of compounds in Table 2A in order to include only those compounds actually used as ingredients in aerosol coating products. In addition, EPA has provided a mechanism to add additional compounds to the table if a regulated entity elects to use them as an ingredient in aerosol coatings. C. Regulatory Limits The regulatory limits for the final rule are a series of reactivity limits for six general coating categories and 30 specialty categories of specialty coatings. These reactivity limits are expressed in terms of grams of ozone generated per gram of product. The reactivity of each VOC ingredient is specified in the table of values included in the regulation. No changes have been made to the regulatory limits since proposal. D. Compliance Dates The final rule requires all regulated entities to comply by January 1, 2009, for all aerosol coating products, except those that require registration under the Federal Insecticide, Fungicide and Rodenticide Act (7 U.S.C. 40 CFR 136-136y) (FIFRA), which are not subject to the requirements of this rule until January 1, 2010. The rule also includes a provision that allows regulated entities to seek a compliance extension if they have not previously manufactured, imported, or distributed in California or elsewhere any aerosol coating product that complies with applicable California regulations. This extension would give the regulated entity until January 1, 2011, to comply with the requirements of the final rule. Beginning on the compliance date, the regulated entities under this rule will be required to conduct initial compliance demonstration calculations for all coating formulations manufactured or filled at each of their facilities, and to maintain compliance demonstration data for each batch of aerosol coating. These calculations and the underlying documents must be maintained for at least 5 years after the product is manufactured, processed, distributed, or imported, and must be submitted to the EPA upon request. The regulated entity may use formulation data to make the compliance calculations; however, EPA is adopting California Air Resources Board Method 310 as the underlying test method (i.e., formulation data must be verifiable with California Air Resources Board Method 310, if requested). Facilities are also allowed to use EPA's Test Method 311. EPA has added a provision allowing the extension of the compliance date for FIFRA-registered compounds as a revision to the proposed rule. This provision was added to the final rule due to the additional approvals (e.g., approval of labels and formulation changes) that must be obtained for all FIFRA-registered products. E. Labeling Requirements The final rule also includes labeling requirements to facilitate implementation and enforcement of the limits. Labels must clearly identify the product category or the category code provided in Table 1 of the regulation, the limit for that product category, and the product date code. If the product date is not obvious from the date code, an explanation of the code is required in the initial notification discussed below. In the final rule, EPA has made a change to allow a regulated entity to develop a facility-specific category code system, if the system is explained in the initial notification. F. Recordkeeping and Reporting The final rule includes a requirement for an Initial Notification from all regulated entities to EPA at least 90 days before the compliance date. This notification will provide basic information about the regulated entity as well as contact information for the certifying official. In addition, this notification will need to explain the product date code system used to label products and the category code system, if the facility is not using the default category codes included in Table 1. The Initial Notification must also include VOC formulation data for each aerosol coatings product that is subject to this rule. The formulation data must provide the weight fraction (g compound/g product) for each VOC compound used in the product in an amount equal to or greater than 0.1 percent. The notification must also identify any volatile organic compound or mixture that is not currently listed in Table 2A, 2B, or 2C, if that compound or mixture will be used in an aerosol coatings formulation. Finally, the notification must include a statement certifying that all of the regulated entity's products will be in compliance with the limits by the compliance date. The regulated entity is required to submit a revised notification if there is a change in the information in the Initial Notification, with the exception of changes to product formulations. The regulated entity is not required to submit a revised notification if the VOC formulations submitted in its Initial Notification change. The regulated entity is required to submit a revised notification if the manufacturer, for example, adds a new coating category, changes the product date code system or batch definition, or begins to use a VOC that is not listed in Table 2A, 2B, or 2C. The regulated entity is required to maintain compliance calculations for each of its aerosol coatings formulations. For each batch of a particular formulation, the regulated entity must maintain records of the date(s) the batch was manufactured, the volume of the batch, and the VOC formula for the formulation. Records of these calculations must be maintained for 5 years after the product is manufactured, processed, distributed for [[Page 15611]] wholesale, or imported for sale or distribution in interstate commerce in the United States. The regulated entity must supply this information to EPA within 60 days of a written request. The final rule includes the addition of a provision that allows for manufacturers or importers to accept the responsibility for recordkeeping and reporting requirements that would otherwise be required of their distributors. The promulgated rule requires that every 3 years, beginning with calendar year 2011, each regulated entity must submit a triennial report. The triennial report would provide updated VOC formulation data and, for each VOC formulation, the total mass of each individual VOC or mixture used as ingredients in the aerosol coatings manufactured, imported, or distributed that year. This information must be provided only for the second year of the reporting cycle, which in the case of the first report would be information from 2010. Subsequent reports will be required at three year intervals. In other words, a report containing data from 2013 will be due in 2014, a report containing data from 2016 will be due in 2017, and so forth. EPA intends to provide mechanisms for regulated entities to provide this information through the electronic submission facilities being expanded under the National Emissions Inventory (NEI) program and will provide additional information and guidance to regulated entities before the first report is due. This report has been added to the final rule to address concerns raised during the public comment period, as explained in section III.E of this preamble. The final rule requires those small manufacturers who qualify for exemption from the limits of Table 1 of subpart E to make an annual report to EPA providing necessary information and documentation to establish that the products made by the entity should be exempt. EPA notes that the contents of any reports, including the VOC composition of the coatings subject to this rule, are ``emissions data'' under section 114 of the CAA and EPA's regulatory definition of such term in 40 CFR part 2. As such, this information must be available to the public regardless of whether EPA obtains the information through a reporting requirement or through a specific request to the regulated entity. Therefore, such information is not eligible for treatment as ``confidential business information'' under 40 CFR 59.516 of this rule. G. Variance The final rule allows regulated entities to submit a written application to EPA requesting a temporary variance if, for reasons beyond their reasonable control, they cannot comply with the requirements of the rule. An approved variance order would specify a final compliance date and a condition that imposes increments of progress necessary to assure timely compliance. A variance would end immediately if the regulated entity failed to comply with any term or condition of the variance. The Administrator will provide special consideration to variance requests from regulated entities, particularly small businesses that have not marketed their products in areas subject to State regulations for these products prior to this rulemaking. EPA notes that a variance under EPA's national rule for aerosol coatings under section 183(e) does not alter any requirements under any applicable State or local regulations. No changes were made to this section since the proposal. H. Test Methods Although regulated entities may use formulation data to demonstrate compliance with the reactivity limits, EPA concludes it is also necessary to have test methods in place that can be used to verify the accuracy of the formulation data. Therefore, we have included two test methods that may be used by regulated entities or EPA to determine compliance with the reactivity limits. In those cases where the formulation data and test data are not in agreement, data collected using the approved test methods will prevail. Regulated entities or regulatory agencies may use either California Air Resources Board Method 310--Determination of Volatile Organic Compounds in Consumer Products and Reactive Organic Compounds in Aerosol Coating Products, or EPA Method 311--Analysis of Hazardous Air Pollutant Compounds in Paints and Coatings in Paints and Coatings by Direct Injection into a Gas Chromatograph (40 CFR part 63, appendix A) to determine the reactive organic compound content of an aerosol coating. California Air Resources Board Method 310 includes some test procedures that are not required to determine the VOC content of aerosol coatings; for example, California Air Resources Board Method 310 incorporates EPA Method 24 for determining the VOC content of a coating. We have identified those sections of California Air Resources Board Method 310 that are not required for compliance demonstration purposes in the regulation. EPA Method 311--Analysis of Hazardous Air Pollutant Compounds in Paints and Coatings by Direct Injection into a Gas Chromatograph (40 CFR part 63, appendix A) was originally developed for liquid coatings, so it does not include provisions for the collection of the propellant portion of an aerosol coating. Therefore, those choosing to use EPA Method 311-- Analysis of Hazardous Air Pollutant Compounds in Paints and Coatings by Direct Injection into a Gas Chromatograph (40 CFR part 63, appendix A) must separate the aerosol propellant from the coating using either ASTM D3063-94 or ASTM D 3074-94. There were no changes to the test methods in the final rule. III. Response to Significant Comments During the public comment period, we received a total of 18 comment letters. Of these, seven were brief letters in support of the proposed regulation. A summary of the most significant comments is presented below. A summary of all comments received on this rule, as well as complete responses to each of these comments, are presented in the docket (EPA-HQ-OAR-2006-0971). A. Format of Regulation Several commenters discussed the use of a reactivity-based rule versus a mass-based rule. Two commenters fully supported the reactivity-based rule, while five commenters raised some concerns over some aspects of this approach. The commenters supporting the rule generally supported the use of a reactivity-based approach both nationally and in California. One commenter stated that EPA did a good job in evaluating the reactivity regulation in California and the feasibility of making it apply nationwide, calling it a ``bold step forward in the arena of air quality regulations.'' Another commenter stated that ``[t]he rule is an important advancement in the use of reactivity-based emissions regulations for VOC.'' The commenter provided the following points in support of this rule and the future use of reactivity-based VOC emission limits in other consumer product and coating standards: 1. Reactivity-based VOC emission regulations are more appropriate and effective for addressing the environmental concern of interest, ozone formation potential. 2. This national proposed rule is based on an established CARB regulation for aerosol coatings which has already been approved by EPA and in use for several years. [[Page 15612]] 3. Reactivity-based VOC emission regulations provide product formulators with more options for meeting environmental performance standards while providing technically feasible product performance, and stimulating future product development enhancements. 4. There is evidence that lower mass-based VOC limits in some products may be leading to the increased use of more photochemically reactive VOC, eliminating some of the anticipated environmental benefit (ozone reduction) of these regulations, and possibly increasing the actual ozone formation potential of the products themselves. This commenter also stated that the reactivity-based approach is consistent with EPA's September 2005 ``Interim Guidance on Control of Volatile Organic Compounds in Ozone State Implementation Plans,'' which specifically ``encourages States to consider recent scientific information on the photochemical reactivity of volatile organic compounds in the development of state implementation plans designed to meet the national ambient air quality standards for ozone [70 FR 54046- 54051; September 13, 2005].'' The commenter concluded that reactivity-based VOC standards should not be considered ``only as a supplement to mass-based approaches, but as a scientifically valid and appropriate means for controlling ozone formation.'' The commenter also stated that in its approval of the CARB regulation, EPA appropriately stated that the reactivity-based rule will improve the SIP in part by ``creating an incentive for the use of solvents with relatively low contribution to ozone formation [70 FR 1642].'' The commenter further stated that some VOC mass-based limits in the previous version of CARB's aerosol coatings rule ``presented particularly difficult reformulation challenges'' for product manufacturers [70 FR 1642]. The commenter stated that EPA correctly noted that CARB's regulation will preserve the air quality benefits of its previous rule, while at the same time allowing manufacturers greater flexibility in reformulating their products, by replacing existing mass-based VOC limits for aerosol spray coatings with reactivity-based limits that are designed to achieve equivalent air quality benefits [70 FR 1642]. The commenter concluded that expanding this aerosol coating regulation to the rest of the United States expands the benefits of this working reactivity-based VOC regulation to other areas of the United States where ozone formation is a concern, while allowing aerosol coating manufacturers to develop single formulations for the entire United States. Several commenters raised concerns over some aspects of an approach based on reactivity. These commenters stated that a reactivity-based approach may have merit, but only if EPA first addresses numerous ``unanswered questions'' about the potential adverse impact of such an approach on other equally, if not more, important components of air quality management programs, such as the effect on ambient fine particulate matter (PM2.5) levels and air toxics. The commenters also raised the issues of downwind ozone impacts and enforceability. One commenter provided an extensive history of the evolution of EPA's use of reactivity, noting that EPA is not obligated to issue a reactivity- based regulation, stating that the required reactivity-based portion of EPA's obligation und