Nitrogen oxides from oil and gas

Background

Oil and gas exploration and production processes are collectively known as the upstream operations. Upstream oil and gas operations include:

• Drilling new oil and gas wells.
• Hydraulic fracturing, or fracking. This involves injecting water, sand, or other materials into a well to help with extracting oil and gas.
• Completing oil and gas wells. This can involve encasing a well in concrete or other steps to prepare it for production.
• Producing or extracting oil or gas from wells.

Upstream oil and gas operations are a significant source of nitrogen oxides, or NOx emissions. NOx emissions, along with volatile organic compound emissions, are what’s known as ozone precursors. That means when NOx emissions react with volatile organic compound emissions in heat and sunlight, they form harmful ground-level ozone pollution. 
In March 2023, Governor Polis directed the Air Pollution Control Division to develop rules that will apply to upstream oil and gas operators in areas of Colorado that do not meet federal ozone pollution standards. According to Governor Polis’s direction, these operations need to achieve:

• A 30% reduction in NOx by 2025.
• At least a 50% reduction in NOx by 2030.

In December 2023, Colorado took action designed to meet the 2025 NOx reduction target. The Colorado Air Quality Control Commission achieved this by implementing regulations to reduce emissions from stationary engines and drilling and fracking operations.

In December 2023, the commission also established the planning process for actions to meet the 2030 NOx reduction target. To help explore options, the commission directed the division and the Colorado Energy and Carbon Management Commission to establish a new NOx Reduction Steering Committee.

In March 2024, the CDPHE Air Pollution Control Division established the NOx Reduction Steering Committee and began the planning process to meet the 2030 reduction target.

The division is also requiring oil and gas operators to collect the NOx emissions data during the ozone season (May-September) and submit that information. The division will use these reports to inform actions to help reduce NOx emissions.

2025 NOx intensity interim data

The interim NOx intensity data for the 2025 ozone season is now available. The pre-production and production operation statistics that describe the activities oil and gas operators undertook during the 2025 ozone season are listed below. This data is preliminary and is presented to give a snapshot of the progress of the NOx intensity program.

Table 1: 2025 interim operator intensity performance

Table 2: Sector summary

Tables 1 and 2 represent the general results of the 2025 interim submissions. Table 1 includes the intensity targets for operators, whether they met them or not, and if they achieved reductions in excess of their targets. Table 2 summarizes the operators’ figures and presents the interim sector-wide NOx intensity. All data presented in the tables is available for download below.

2024 NOx intensity data

The NOx intensity data for the 2024 ozone season are available. The pre-production and production operation statistics that describe the activities oil and gas operators undertook during the 2024 ozone season are listed below. This data represents the information submitted by operators to the interim NOx intensity form and the ONGAEIR program for the 2024 reporting year. The numbers included may change as further review and verification occur. Interim 2024 data is available for download below.

Table 3: Operator intensity performance

Table 4: Sector summary

Tables 3 and 4 represent the general results of the interim and annual submissions.

Table 3 includes the intensity performance for operators in both the interim and annual submissions, the 2024 NOx intensity target, and whether they met the target.

Table 4 summarizes the operators’ figures, presents both the interim and annual sector-wide NOx intensity performance, and the differences between the two submissions. Table 5 compares the 2024 annual emissions tonnage against the 2017 baseline emissions year values.

Table 5: 2017 Baseline year emissions comparison

Datasets

The data is available for download in a Comma-Separated Values (CSV) format. Validation marks created through the data certification process are still present in this data. They take the form of: (RAB), and [;]. 

• (RAB) is an abbreviation of “Received as blank” and indicates a cell that had no information in it when received.
• [;] stands for an instance where there was a comma present in the original submission, which had to be stripped for compilation purposes.

NOx intensity reporting for operators

Upstream oil and gas operators in the 8-hour ozone nonattainment area must submit interim ozone season NOx intensity reports by Nov. 30 for years 2024, 2025, and 2026.  The reports are required under Air Quality Control Commission Regulation 7, Part B, Section VI.

Calculation methodology and emission factors

Sources with permitted methodologies for pollutants must use those to calculate pollutants. Refer to the Calculation Methodology: Guidance document for more information. 

Submission procedure

Submit interim ozone season NOx intensity reports and any associated supporting documentation to cdphe_apcd_nox@state.co.us.

• Title the files as follows for submission:
  • NOx Intensity Form: [Year]_[CompanyName]_NIF.xlsx
  • Supporting Documentation: [Year]_[CompanyName]_TSD[#].docx (or) .pdf

Forms and instructions are provided below, organized by reporting calendar year. 

• Guidance document.
• Interim Ozone Season NOx Intensity Reporting form.

NOx Intensity documents changelog

Nov. 1, 2025

NOx Intensity Form updated to v1.2; minor language changes in accordance with the interim 2025 reporting year.

NOx Intensity Guidance was updated to v1.4; minor language changes.

2024 reporting - Interim ozone season NOx intensity

The 2024 operator submissions data is provisional and subject to revision and validation by division staff. Available data was provided by operators and may be resubmitted by operators at any time. For the most recent data or if a reporting error is observed,  email cdphe_apcd_nox@state.co.us.

NOx Reduction Steering Committee

The air division convened a Nitrogen Oxide Reduction Steering Committee from March 2024 through May 2025. The committee helped develop recommendations to reduce NOx pollution from upstream oil and gas operations.