thereof, which directly or indirectly results or may result in emissions of any air pollutant at any location which will prevent the attainment or maintenance of a national standard.

(5) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources.

(6) Require owners or operators of stationary sources to install, maintain, and use emission monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; also authority for the State to make such data available to the public as reported and as correlated with any applicable emission standards or limitations.

(b) Where a plan sets forth a control strategy that provides for application of (1) inspection and testing of motor vehicles and/or other transportation control measures or (2) land use measures other than those referred to in § 51.11(a) (4), such plan shall set forth the State's timetable for obtaining such legal authority as may be necessary to carry out such measures.

(c) The provisions of law or regulation which the State determines provide the authorities required under this section shall be specifically identified, and copies of such laws or regulations shall be submitted with the plan.

(d) (1) Except as otherwise provided by paragraph (b) of this section, the plan shall show that the legal authorities specified in this section are available to the State at the time of submission of the plan.

(2) Legal authority adequate to fulfill the requirements of paragraph (a) (5) and (6) of this section may be delegated the State pursuant to section 114 of the Act.

(e) A State governmental agency other than the State air pollution control agency may be assigned responsibility for carrying out a portion of a plan: Provided, That such plan demonstrates, to the Administrator's satisfaction, that such State governmental agency has the legal authority necessary to carry out such portion of the plan or, pursuant to paragraph (b) of this section, has a timetable for obtaining such authority.

(f) The State may authorize a local agency to carry out a plan, or portion

thereof, within such local agency's jurisdiction: Provided, That such plan demonstrates, to the Administrator's satisfaction, that such local agency has the legal authority necessary to implement such plan, or portion thereof, and further: Provided, That such authorization shall not relieve the State of responsibility under the Act for carrying out such plan, or portion thereof..

[36 FR 22398, as amended at 38 FR 15836, June 18, 1973]

§ 51.12 Control strategy: General.

(a) In any region where existing (measured or estimated) ambient levels of a pollutant exceed the levels specified by an applicable national standard, the plan shall set forth a control strategy which shall provide for the degree of emission reduction necessary for attainment and maintenance of such national standard, including the degree of emission reduction necessary to offset emission increases that can reasonably be expected to result from projected growth of population, industrial activity, motor vehicle traffic, or other factors that may cause or contribute to increase emissions.

(b) In any region where measured or estimated ambient levels of a pollutant are below the levels specified by an applicable secondary standard, the plan shall set forth a control strategy which shall be adequate to prevent such ambient pollution levels from exceeding such secondary standard.

(c) Portions of a control strategy applicable to area sources may differ from portions applicable to point sources.

(d) For purposes of developing a control strategy, data derived from measurements of existing ambient levels of a pollutant may be adjusted to reflect the extent to which occasional natural or accidental phenomena, e.g., dust storms, forest fires, industrial accidents, demonstrably affected such ambient levels during the measurement period.

(e) The plan shall identify those areas (counties, urbanized areas, standard metropolitan statistical areas, et cetera) which, due to current air quality and/or projected growth rate, may have the potential for exceeding any national standard within the subsequent 10-year period.

(1) For each such area identified, the plan shall generally describe the intended method and timing for producing the analysis and plan required by paragraph (g) of this section.

(2) The area identification and description of method and timing required by this paragraph shall be submitted no later than 9 months following the effective date of this paragraph.

(3) At 5-year intervals, the area identification shall be reassessed to determine if additional areas should be subject to the requirements of paragraph (g) of this section.

(f) Based on the information submitted by the States pursuant to paragraph (e) of this section, the administrator will publish, within 12 months of the effective date of this paragraph, a list of the areas which shall be subject to the requirements of paragraph (g) of this section.

(g) For each area identified by the administrator pursuant to paragraph (f) of this section, the State shall submit, no later than 24 months following the effective date of this paragraph, the following:

(1) An analysis of the impact on air quality of projected growth and development over the 10-year period from the date of submittal.

(2) A plan to prevent any national standards from being exceeded over the 10-year period from the date of plan submittal. Such plan shall include, as necessary, control strategy revisions and/or other measures to insure that projected growth and development will be compatible with maintenance of the national standards throughout such 10year period. Such plan shall be subject to the provisions of § 51.6 of this part.

(h) Plans submitted pursuant to paragraph (g) of this section shall be reanalyzed and revised where necessary at 5-year intervals.

[36 FR 22398, as amended at 38 FR 15836, June 18, 1973]

through the application of reasonably available control technology, “reasonable time" for attainment of such secondary standard, pursuant to § 51.10 (c), shall be not more than 3 years unless the State shows that good cause exists for postponing application of such control technology.

(2) In any region where application of reasonably available control technology will not be sufficient for attainment and maintenance of such secondary standard, or where the State shows that good cause exists for postponing the application of such control technology, "reasonable time" shall depend on the degree of emission reduction needed for attainment of such secondary standard and on the social, economic, and technological problems involved in carrying out a control strategy adequate for attainment and maintenance of such secondary standard.

(c) For purposes of developing a control strategy, background concentration shall be taken into consideration with respect to particulate matter. As used in this subpart, "background concentration" is that portion of the measured ambient levels of particulate matter that cannot be reduced by controlling emissions from manmade sources; "background concentration" shall be determined by reference to measured ambient levels of particulate matter in nonurban areas.

(d) Example regions:

(1) A control strategy which provides for the attainment and maintenance of a national standard for sulfur oxides or particulate matter in any region in a State (excluding Priority IA regions) will be deemed by the Administrator to be adequate for attainment and maintenance of such standard in any or all other regions of the same Priority classification in which measured or estimated levels of the pollutant are lower than those in the region for which the control strategy was formulated: Provided, That such control strategy is sufficiently comprehensive to include adequate control of sulfur oxides or particulate emissions from sources listed in Appendix C to this part. Any region (i) for which the State formulates a control strategy which is applied to other regions or (ii) for which a control strategy is developed, without regard to whether such strategy is applied outside of the region, is referred to hereinafter as an "example region."

(2) The State shall obtain, through the appropriate Regional Office, the concurrence of the Administrator in the selection of an example region.

(3) Nothing in this section shall be construed in any manner to preclude a State from preparing, adopting, and submitting a separate plan for each region. (e) Adequacy of control strategy:

(1) The plan shall demonstrate that the control strategy for each national standard for sulfur oxides or particulate matter is adequate for attainment and maintenance of such standard in the example region (s) to which it applies. The adequacy of a control strategy shall be demonstrated by means of a proportional model or diffusion model or other procedure which is shown to be adequate and appropriate for such purpose.

(2) (i) If such demonstration is made by use of a proportional model, such model shall be one in which the following equation is employed to calculate the degree of improvement in air quality needed for attainment of a national standard:

A Existing air quality at the location having the highest measured or estimated concentration in the region. B=Background concentration. C National standard.

(ii) The above equation does not account for topography, spatial distribution of emissions, or stack height, but the significance of these parameters shall be considered in developing the control strategy.

(iii) The plan shall show that application of the control strategy will result in the degree of emission reduction indicated to be necessary by the above calculation, as modified by appropriate consideration of factors set forth in subdivision (ii) of this subparagraph. The plan shall contain a summary of the computations used to determine the emission reductions that will result from application of the control strategy to each point source and group of area sources; such summary shall be included in a table similar to that presented in Appendix D to this part. The detailed computations shall be retained and be made available for inspection by the Administrator.

(3) (i) If such demonstration is made by use of a diffusion model, such model

shall be identified and described: Provided, however, That if either of the two diffusion models described in the following publications is used, it need only be identified:

Air Quality Implementation Planning Program (IPP), Volume I, Operator's Manual, National Air Pollution Control Administration, Environmental Protection Agency, Washington, D.C., November 1970.

Air Quality Display Model (AQDM), National Air Pollution Control Administration, Department of Health, Education, and Welfare, Washington, D.C., November 1969.

(ii) The plan shall contain a summary of emission levels expected to result from application of the control strategy, which summary shall be included in a table similar to that presented in Appendix D to this part.

(iii) The plan shall also show the air quality levels expected to result from application of the control strategy, presented either in tabular form or as an isopleth map showing maximum pollutant concentrations and expected concentration gradients. Computer printouts of the input and output data associated with use of a diffusion model shall be retained and made available for inspection by the Administrator.

(f) Emission data:

(1) Each plan shall include the following data on emissions of sulfur oxides and particulate matter;

(i) For each example region in the State, a detailed inventory of emissions from point sources and area sources in each county shall be summarized in a form similar to that shown in Appendix D, and the data described in Appendices E and F to this part shall be retained and made available for inspection by the Administrator.

(ii) For all regions, point-source and area-source data shall be submitted in summary form, as shown in Appendix G, except that for regions classified as Priority III, only point-source data and any existing area-source data shall be submitted. Data described in Appendices E and F to this part shall be retained and made available for inspection by the Administrator.

(g) Air quality data: Data showing existing air quality with respect to sulfur dioxide and particulate matter shall be submitted for each example region. Actual measurements shall be used where

available if based on use of the measurement methods specified in § 51.17; sulfur dioxide measurements based on use of the continuous conductimetric method also will be acceptable for this purpose. If actual measurements are not available and cannot be made in time to be employed in the development of the control strategy, air quality may be estimated by the procedure described in Appendix A to this part. Air quality data, whether measured or estimated, shall be submitted in a form similar to that shown in Appendix H to this part. § 51.14 Control strategy: Carbon monoxide, hydrocarbons, photochemical oxidants, and nitrogen dioxide.

(a) Priority I Regions. (1) Each plan for a region classified Priority I with respect to carbon monoxide, photochemical oxidants, or nitrogen dioxide shall set forth a control strategy which shall provide for the degree of emission reduction necessary for attainment and maintenance of the national standard for each such pollutant after consideration of the emission reductions that will result from the application of Federal motor vehicle emission standards promulgated pursuant to section 202 of the Act.

(2) The plan shall contain:
(i) A

description of enforcement methods including, but not limited to, procedures for monitoring compliance with the selected traffic control measures, procedures for handling violations, and a designation of enforcement responsibilities (i.e., air pollution control agency, State police, State Department of Motor Vehicles, State Registrar of Motor Vehicles, etc.).

(ii) Proposed or adopted rules and regulations pertaining to the selected transportation control measures.

(iii) A description of administrative procedures to be used in implementing all selected transportation control measures, including, but not limited to, methods of achieving transportation improvements and a designation of responsibility for administration of such procedures (e.g., State Treasurer responsible for purchase of buses).

(iv) A schedule designating dates by which legal authority necessary to implement the plan will be obtained, other significant steps in the implementation of the plan will be achieved, and each control measure will be implemented.

(b) Control strategy development. In a region in which attainment and maintenance of a national standard will require emission reductions in addition to those which will result from application of the Federal motor vehicle emission standards, the control strategy shall provide for application of such other measures as may be necessary for attainment and maintenance of such national standard.

(c) Adequacy of control strategy (1). The plan shall demonstrate, by means of a proportional model or diffusion/photochemical model or other

procedure which is adequate and appropriate, that the control strategy included in each plan for a region classified as priority I is adequate for attainment and maintenance of the national standard(s) to which such control strategy applies. Control measures shall not result in an increase in the concentration of any pollutant to a level that exceeds a national ambient air quality standard. The plan shall include provisions as necessary to prevent such increases in concentrations as a result of traffic increases that may be stimulated by transportation control

measures.

(2) With respect to control of carbon monoxide and nitrogen oxides, the proportional model which may be used for purposes of this paragraph is described in § 51.13(e) (2): Provided, With respect to the national standard for nitrogen dioxide, that the degree of air quality improvement indicated to be necessary by the proportional model will be achieved by a corresponding degree of reduction of total nitrogen oxides emissions from stationary and mobile sources.

(3) In any region where the degree of nitrogen oxides emission reduction necessary for attainment and maintenance of the national standard for nitrogen dioxide is greater than that which can be achieved by the application of (i) the Federal motor vehicle emission standards promulgated under section 202 of the Act and (ii) any transportation control measures which may be necessary for attainment and maintenance of the national standards for carbon monoxide and photochemical oxidants, the plan shall provide for the degree of nitrogen oxides emission reduction attainable through the application of reasonably available control technology.

(4) With respect to hydrocarbons and photochemical oxidants, it may be assumed that (i) there is no background concentration of photochemical oxidants and (ii) the degree of total hydrocarbon emission reduction necessary for attainment and maintenance of the national standard for photochemical oxidants will also be adequate for attainment of the national standard for hydrocarbons. The proportional model to be used to determine the necessary hydrocarbon emission reduction is set forth in Appendix J to this part.

(5) The plan shall show that the control strategy including transportation control measures will result in the degree of emissions reduction indicated to be necessary by a proportional model, diffusion model, or other procedure which is adequate and appropriate. The plan shall contain a summary of the computations, assumptions and judgments used to determine the emissions reductions that will result from application of the control strategy to each point source, and each group of area sources. Such summary shall be included in a table similar to that presented in appendix D to this part. The plan also shall contain a sum

Pollutants

mary of the data, computations, assumptions and judgments used to develop any transportation control measures that are a part of the control strategy. Such a summary shall as a minimum contain the material described in appendix M to this part. The detailed computations and data shall be retained by the State and made available for inspection by the Administrator at his request.

(6) If a diffusion/photochemical model is used, the plan shall include a description of such model.

(d) Emission data. Emission data on carbon monoxide, hydrocarbons, and nitrogen oxides shall be submitted in accordance with the requirements of § 51.13(f).

(e) Air quality data. Data showing existing air quality levels shall be presented in accordance with this section:

(1) For Priority I regions, data on carbon monoxide, nitrogen dioxide, and photochemical oxidants shall, as a minimum, include the results of measurements made during a period of approximately 3 months beginning on or about July 1, 1971, in accordance with the following procedures.

1 Equivalent methods are specified in § 420.17. (2) For Priority I regions, only available air quality data for hydrocarbons must be submitted.

(3) For Priority III regions, no air quality data for carbon monoxide, hydrocarbons, nitrogen dioxide, and photochemical oxidants need be submitted.

(4) Air quality data required by this subparagraph shall be submitted in the form similar to that shown in Appendix H to this part.

(f) Motor vehicle emission factors.— The States required to submit transportation control plans must, except as noted below, use current emission factors and methodology to calculate emissions from gasoline powered motor vehicles. The current emission factors and methodology are presented in "Compila

tion of Air Pollutant Emission Factors," EPA Report No. AP-42, and in superseding EPA interim reports. These are available from the EPA, Office of Air Quality Planning and Standards, Research Triangle Park, N.C. 27711. If emissions factors or methodology other than those presented in the EPA report are used, the substantiating justification must be submitted with the transportation control

measures.

(g) Air quality base line.—The concentrations of carbon monoxide and photochemical oxidants set forth in the State plan as approved and promulgated on May 31, 1972 (37 FR 10842), (part 52 of this chapter), may be used as the air quality base lines for computation of the emissions reductions through transporta