N.Y. Comp. Codes R. & Regs. tit. 6, § 212-1.5 – Determining applicable emission standards for process operations.

(a) In instances where air contaminants from two or more process emission sources may be simultaneously emitted to the outdoor atmosphere through a single emission point, the permissible emission rate or degree of air cleaning required is determined by using the sum of the process weights or emission rate potentials for all process emission sources.
(b) In instances where air contaminants from a single process emission source are emitted to the outdoor atmosphere through more than one emission point, the sum of the emissions from all such emission points shall not exceed the quantity that would be authorized through a single emission point.
(c) In instances where air contaminants from two or more process emission sources are emitted to the outdoor atmosphere through a single emission point and the applicable emission standard for one or more process emission sources, if vented separately to the outdoor atmosphere, is a concentration standard (grains per standard cubic foot), the permissible emission rate through such emission point shall not exceed the quantity that would be authorized if the emissions were through separate emission points.
(d) In instances where a facility owner or operator can demonstrate to the satisfaction of the department that the facility owner or operator will apply BACT for criteria air contaminants or T-BACT for non-criteria air contaminants, the department may specify a less restrictive permissible emission rate or degree of air cleaning for the process emission source or emission point than required under Subpart 212-2 of this Part.
1. (1) A process emission source subject to a Federal NSPS under 40 CFR part 60 (see table 1, section 200.9 of this Title) satisfies the requirements of this Part for the respective air contaminant regulated by the Federal standard if the facility owner or operator can demonstrate that the facility is in compliance with the relevant Federal regulation.
2. (2) A process emission source subject to the Federal National Emission Standards for Hazardous Air Pollutants (NESHAP) under 40 CFR part 61 or part 63 (see table 1 of section 200.9 of this Title) satisfies the requirements of this Part for the respective air contaminant regulated by the Federal standard if the facility owner or operator can demonstrate that the process emission source is in compliance with the relevant Federal regulation and, for those NESHAPs regulating HTACs found in section 212-2.2, table 2 – high toxicity air contaminant list, of this Part, provide a TIA demonstrating that the maximum offsite ambient air concentration is less than the AGC/SGC or meeting the mass emission limit identified in Section 212-2.2, Table 2 of this Part. Either compliance option must have actual emissions less than the PB trigger for the respective air contaminant. Facility owners or operators required to submit a TIA shall submit a protocol describing the procedures to be used to predict the maximum offsite ambient air concentration. Once the protocol is approved by the department and the TIA is conducted, the facility owner or operator shall submit a final report to the department along with the air dispersion modeling results for approval. The department requires the use of an EPA approved air dispersion model for all screening and/or refined air dispersion modeling assessments; however, screen dispersion models do not require an approved modeling protocol.
(e)
(f) Facility owners or operators whose process operations emit NO_x or VOCs and meet the applicability requirements of Subpart 212-3 or Subpart 212-4 of this Part are not subject to the control provisions in Subpart 212-2 of this Part for NO_x or VOCs. However, if an individual air contaminant, as a component of total VOCs, is assigned an environmental rating of A, that individual air contaminant must meet the control requirements of Subpart 212-2 of this Part.
(g) At all times, the facility owner or operator must operate and maintain all process emission sources, including the associated air pollution control and monitoring equipment, in a manner consistent with safety, good air pollution control practices, good engineering practices and manufacturers’ recommendations for minimizing emissions.