Section 52.278 - Oxides of nitrogen control(a) The following regulations are disapproved because they relax the control of nitrogen oxides emissions without an accompanying analysis demonstrating that this relaxation will not interfere with the attainment and maintenance of the National Ambient Air Quality Standards.(1) South central coast intrastate AQCR.(i) San Luis Obispo County APCD.(A) Rule 405(A)(1), Nitrogen Oxides Emission Standards Limitations and Prohibitions submitted on November 10, 1976, is disapproved; and Rule 114(4), Gaseous Contaminants Oxides of Nitrogen submitted on February 21, 1972 and previously approved in 40 CFR 52.223 , is retained.43 FR 34467, Aug. 4, 1978