No owner or operator of an installation producing nitric acid, either as an end product or for use in intermediate steps in production of other products, will allow emissions of oxides of nitrogen (calculated as nitrogen dioxide) to exceed 5.5 pounds per ton of 100 percent nitric acid produced, or a concentration equivalent to 400 parts per million (ppm) by volume, whichever is more stringent. Compliance with the nitrogen oxides emission limit is determined using the arithmetic average of three contiguous one-hour periods. This will apply unless:
129 Neb. Admin. Code, ch. 16, § 002