NOx Testing Flexibilities for Boilers and Heaters

Summary#

These are the final Regulations Amending the Multi-Sector Air Pollutants Regulations (published in the Canada Gazette Part II). They give operators more time and more flexible ways to test nitrogen‑oxides (NOx) from industrial boilers and heaters so some units can be reclassified instead of being automatically treated as the worst performing class. The regulations were registered on November 21, 2025 and published on December 3, 2025.

What it does#

• Extends the deadline to complete a valid NOx classification test for certain pre‑existing boilers and heaters to December 31, 2025.
• Lets operators test a group of units that share a single chimney (a “common stack”) and use the shared test result to assign NOx values to each unit, with rules for how to split the result when the stack also serves other equipment.
• Adds safety flexibilities for testing:
  • test runs can be shorter than 30 minutes if a longer run would risk damage or be unsafe;
  • units can operate below 60% of rated capacity during a test if running at 60% would be unsafe.
• Changes how “rated capacity” is set for pre‑existing units: it will be the lower of the nameplate at commissioning or the current nameplate (so conversions that reduced capacity are recognized).
• Adds a way to reclassify units that were shut down (using design records) so they can be assigned a lower NOx class before being restarted.
• Accepts two more gas analysis methods from the GPA Midstream Association: GPA 2261‑25 and GPA 2286‑24 for measuring fuel composition.
• Adjusts the fuel‑change trigger that forces retesting by lowering the methane threshold for “natural gas” from 90% to 85%, and adds flexibility so small fluctuations around that threshold do not force repeated tests.
• Makes related reporting and recordkeeping changes to reflect the above testing options.

Who's affected#

• Operators and owners of industrial boilers and heaters regulated under Part 1 of the Multi‑Sector Air Pollutants Regulations. About 1,300 boilers and heaters are covered by Part 1 in Canada, but the amendments target a subset.
• The changes were aimed mainly at 218 specific pre‑existing boilers and heaters that had not produced a valid test result by the original deadlines; of those, at least 41 had confirmed testing or safety issues.
• The largest group of affected units is in the oil and gas sector (most of the 218 are in Alberta and oil and gas facilities). Other sectors include chemicals, pulp and paper, power plants, and potash.
• Testing firms, consultants and engineering contractors who do stack testing or install NOx controls may see more or different work because of the retesting window and new testing options.
• Local communities and public health interests may notice small timing changes in when stricter emissions limits take effect at particular facilities.

Why it matters#

• Without these amendments, boilers and heaters that missed the original testing window could be automatically treated as the worst performing class (Class 80) and face a strict NOx limit of 26 g/GJ starting January 1, 2026, often meaning costly retrofits or replacements.
• The change gives operators a realistic, safer chance to demonstrate the true NOx performance of their units and avoid unnecessary upgrades. The government estimates avoided capital costs of about $14,483,047 (present value, 2024 dollars) for operators across the affected units.
• There is a trade‑off: because some units may not be upgraded as quickly under the amended timeline, the analysis estimates up to 25,333 tonnes of additional NOx emitted across 2025–2035 compared with a scenario where all affected units were immediately upgraded. The analysis expects minimal change to the overall long‑term health benefits projected under the original 2016 rules.
• Practically, the amendments reduce unsafe or impractical testing requirements, clarify how to test multi‑unit chimneys, and recognize real‑world fuel and equipment conditions so classification better matches actual performance.