Boiler Flue Emissions Permits are issued through the Colorado Department of Public Health & Environment – Air Quality Control Division. Various undesirable pollutants that could enter the Denver air-shed are controlled and minimized using approved industries standards and technological approaches. These include: burning clean fuels (specified diesel with formulated low sulfur content), flue gas recirculation (technology that minimizes flue NOx level prior to release to the atmosphere), high efficiency low-NOx burners, and approved precise measurement of fuel input. The emissions permit is in full compliance with CDPHE requirements.