N.Y. Comp. Codes R. & Regs. tit. 6, § 231-5.5
(2) A proposed modification to an existing non-major facility must offset its project emission potential for each nonattainment contaminant for which the project emission potential equals or exceeds the major facility threshold.
(b) Offset ratio.
(3) An emission offset of PM-2.5 (including applicable precursors) must at least equal (offset ratio of one to one or greater) the corresponding facility potential to emit or project emission potential of the same pollutant (subsequent to application of LAER), as appropriate, by the applicable offset ratio specified in Subpart 231-13 of this Part. A greater offset ratio may be required to provide a net air quality benefit as set forth in this section.
(c) Use of an ERC as part of an emission offset.
An ERC must meet the following conditions to be used as part of an emission offset:
(3) an ERC, or portion thereof, must be included as a condition in the permit for the proposed new or modified facility for which the reduction is used.
(d) Net air quality benefit and emission offset location for PM-10, or PM-2.5 (including applicable precursors).
An emission offset of PM-10, or PM-2.5 (including applicable precursors) must meet the following:
(2) Net air quality benefit demonstration. As part of a permit application, the applicant must submit an air quality impact evaluation for PM-10 and PM-2.5, as applicable, in accordance with department approved modeling procedures. The ambient air quality impact analysis must demonstrate that:
(3) Interstate offsets. An emission offset of PM-10 or PM-2.5 (including applicable precursors), may be obtained from areas of equal or higher classification located in another state, in accordance with department approved modeling procedures, provided that an interstate reciprocal trading agreement is in place and the requirements of paragraphs (1) and (2) of this subdivision are met.
(e) Ozone nonattainment and emission offset location.
The department approved modeling procedures must be used by an applicant to find default acceptable VOC or NOx offset source locations within New York State or to perform a case specific contribution demonstration. An emission offset of VOC or NOx is subject to the following:
(1) Proposed new or modified facility located in an ozone nonattainment area.
(i) Intrastate offset sources. An emission offset of VOC or NOx must be obtained from:
(a) Emission offset applicability.