Air quality impact evaluation

(a) Source impact analysis (impact on NAAQS and PSD increment). (1) Required demonstration. The owner or operator of the proposed source or modification shall demonstrate that, as of the source's start-up date, allowable emissions increases from that source or modification, in conjunction with all other applicable emissions increases or AQAC_2026_JUL_SC_7_8_10_RUL 13 June 15, 2026 reductions (including secondary emissions) would not cause or contribute to any increase in ambient concentrations that would exceed: (A) any NAAQS in any air quality control region; or (B) the remaining available PSD increment for the specified air contaminants in any area as determined by the Director. (2) [RESERVED]Alternative offsets approach. If the required demonstration shows that allowable emission increases from the source or modification would cause or contribute to an increase in ambient concentrations exceeding any NAAQS, the applicant may elect to offset air quality impacts by extinguishing sufficient Emission Reduction Credits (ERCs) in accordance with OAC 252:100-10-3, 10-4(b), 10-4(c), and 10-7. (b) Air quality models. (1) All estimates of ambient concentrations required under this Part shall be based on the applicable air quality models, data bases, and other requirements specified in Appendix W of 40 CFR 51 (Guideline on Air Quality Models). (2) Where an air quality model specified in Appendix W of 40 CFR 51 (Guideline on Air Quality Models) is inappropriate, the model may be modified or another model substituted, as approved by the Administrator. Such a modification or substitution of a model may be made on a case-by-case basis or, where appropriate, on a generic basis. Modified or substitute models shall be submitted to the Administrator with written concurrence of the Director. In addition, use of a modified or substituted model must be subject to notice and opportunity for public comment under procedures set forth in Sec. 51.102 as it existed on July 16, 2007. (c) Air quality analysis. (1) Preapplication analysis. (A) Ambient air quality analysis. Any application for a permit under this Part shall contain, as the Director determines appropriate, an analysis of ambient air quality in the area that the major stationary source or major modification would affect for each of the following pollutants: (i) for a new source, each regulated pollutant that it would have the potential to emit in a significant amount; (ii) for a major modification, each regulated pollutant for which it would result in a significant net emissions increase. (B) Monitoring requirements. (i) Non-NAAQS pollutants. For any such pollutant for which no NAAQS exists, the analysis shall contain such air quality monitoring data as the Director determines is necessary to assess the ambient air quality for that pollutant in that area. (ii) NAAQS pollutants. For visibility and any pollutant, other than VOC, for which a NAAQS does exist, the analysis shall contain continuous air quality monitoring data gathered to determine if emissions of that pollutant would cause or contribute to a violation of the NAAQS or any PSD increment. (C) Monitoring method. With respect to any requirements for air quality monitoring of PM10 under OAC 252:100-8-33(e)(1) and (2), the owner or operator of the source or modification shall use a monitoring method approved by the Director and shall estimate the ambient concentrations of PM10 using the data collected by such approved monitoring method in accordance with estimating procedures approved by the Director. (D) Monitoring period. In general, the required continuous air monitoring data shall have been gathered over a period of up to one year and shall represent the year preceding AQAC_2026_JUL_SC_7_8_10_RUL 14 June 15, 2026 submission of the application. Ambient monitoring data gathered over a period shorter than one year (but no less than four months) or for a time period other than immediately preceding the application may be acceptable if such data are determined by the Director to be within the time period that maximum pollutant concentrations would occur, and to be complete and adequate for determining whether the source or modification will cause or contribute to a violation of any applicable NAAQS or consume more than the remaining available PSD increment. (E) Monitoring period exceptions. (i) Exceptions for applications that became effective between June 8, 1981, and February 9, 1982. For any application which became complete except for the monitoring requirements of OAC 252:100-8-35(c)(1)(B)(ii) and 252:100-8- 35(c)(1)(D), between June 8, 1981, and February 9, 1982, the data that 252:100-8- 35(c)(1)(B)(ii) requires shall have been gathered over the period from February 9, 1981, to the date the application became otherwise complete, except that: (I) If the source or modification would have been major for that pollutant under 40 CFR 52.21 as in effect on June 19, 1978, any monitoring data shall have been gathered over the period required by those regulations. (II) If the Director determines that a complete and adequate analysis can be accomplished with monitoring data over a shorter period, not to be less than four months, the data that OAC 252:100-8-35(c)(1)(B)(ii) requires shall have been gathered over that shorter period. (III) If the monitoring data would relate exclusively to ozone and would not have been required under 40 CFR 52.21 as in effect on June 19, 1978, the Director may waive the otherwise applicable requirements of OAC 252:100-8-35(c)(1)(E)(i) to the extent that the applicant shows that the monitoring data would be unrepresentative of air quality over a full year. (ii) Monitoring period exception for PM10. For any application that became complete, except for the requirements of OAC 252:100-8-35(c)(1)(B)(ii) and 252:100-8- 35(c)(1)(D) pertaining to monitoring of PM10, after December l, 1988, and no later than August l, 1989, the data that 252:100-8-35(c)(1)(B)(ii) requires shall have been gathered over at least the period from August l, 1988, to the date the application becomes otherwise complete, except that if the Director determines that a complete and adequate analysis can be accomplished with monitoring data over a shorter period (not less than 4 months), the data that 252:100-8-35(c)(1)(B)(ii) requires shall have been gathered over that shorter period. (F) Ozone post-approval monitoring. The owner or operator of a proposed major stationary source or major modification of VOC who satisfies all conditions of OAC 252:100-8-54 and 40 CFR 51, Appendix S, Section IV as it existed on January 16, 1979, may provide post-approval monitoring data for ozone in lieu of providing preconstruction data as required under OAC 252:100-8-35(c)(1). (2) Post-construction monitoring. The owner or operator of a new major stationary source or major modification shall conduct, after construction, such ambient monitoring and visibility monitoring as the Director determines is necessary to determine the effect its emissions may have, or are having, on air quality in any area. (3) Operation of monitoring stations. The operation of monitoring stations for any air quality monitoring required under this Part shall meet the requirements of 40 CFR 58 Appendix B. AQAC_2026_JUL_SC_7_8_10_RUL 15 June 15, 2026