When used in this Part the following terms shall be interpreted to mean:
A numerically prescribed contaminant level that shall not be exceeded in a specified area of the State. Such contaminant levels may include instantaneous, short term, or long term concentrations of individual contaminants or grouping of contaminants having synergistic effects. Such standards may also be described in terms of net effects resulting from the occurrence of individual contaminants or grouping of various contaminants.
N.Y. Comp. Codes R. & Regs. Tit. 6 §§ 257-1.2