EPA sets nitrogen-oxide (NOx) limits for a taconite (iron-ore) facility — finalizing rules for U.S. Steel's Keetac plant (June 2026)

The U.S. Environmental Protection Agency (EPA) revised its 2013 Federal Implementation Plan (FIP), finalizing nitrogen-oxide (NOx) emission limits for the indurating furnace at U.S. Steel's Keetac taconite facility (Keewatin, Minnesota) (a rule, June 8, 2026). Taconite is an iron-ore feedstock — crushed and concentrated ore processed into pellets usable in blast furnaces — and its processing (indurating) furnaces emit air pollutants.

The rule satisfies the requirement to apply "best available retrofit technology (BART)" at taconite facilities as part of addressing "regional haze" that degrades visibility (e.g., at national parks). The finalized BART limits, all evaluated on a rolling 720-hour average, are: (1) 3.4 pounds of NOx per million BTU when firing exclusively natural gas (enforceable three years after promulgation), and (2) 2.0 lbs NOx/MMBtu when firing any fuel or combination other than exclusively natural gas (enforceable five years after promulgation, unless EPA promulgates a modified limit before then).

The rule also allows the facility, within 52 months of the effective date, to seek an adjustment of the cofiring limit (not to exceed 2.5 lbs NOx/MMBtu on a 720-hour rolling average) based on CEMS data collected after installing NOx-reduction technology.

This is a concrete example of finalizing specific air-pollution limits for an industrial facility, with multi-year lead time for technology installation — illustrating how U.S. environmental regulation is operationalized.