Alcoa Intalco

All areas in Washington state must meet national air quality standards for the six most common air pollutants. One of those pollutants is sulfur dioxide (SO₂).

• From 2017 – 2019, we worked with the Northwest Clean Air Agency to evaluate air quality data from Whatcom County. Data from monitors near Intalco showed SO₂ did not meet the national standard.
• In December 2020, the U.S. Environmental Protection Agency (EPA) designated part of Whatcom County near the smelter to be in nonattainment for this standard. (EPA's decision and response to comments).

Attainment plan

We sent the final plan to bring the area back into attainment (called a State Implementation Plan revision) to EPA for approval and finalized the associated Agreed Order.

The plan describes actions the facility will have to take, including:

• Installing and operating new SO₂ controls
• Merging and increasing the height of stacks
• Limit facility-wide and unit-specific SO₂ emissions
• Different scenarios if the facility should restart before or after April 30, 2025

The Northwest Clean Air Agency, Intalco, and Blue Wolf Capital Partners (a private equity firm interested in purchasing and reopening the facility) participated in the development of the plan.

Next steps

EPA’s oversight of the plan is required under the federal Clean Air Act, and it will provide an opportunity for public comment before making a final decision. Once approved by EPA, the requirements of the attainment plan and Agreed Order become federally enforceable. The Agreed Order requirements are in effect and will be implemented, regardless of EPA's timeline for review and approval.

Why this is important

Breathing elevated levels of SO₂ causes inflammation and tightening of airways and can trigger asthma symptoms. SO₂ typically dissipates very quickly, but people living or working close to sources may be exposed to short-term levels that pose a risk to those with pre-existing breathing or health issues. SO₂ pollution also decreases visibility in the form of haze and contributes to acid rain.

Join our sulfur dioxide attainment email list to learn more about our efforts to monitor and evaluate SO₂ levels in Washington.

Updated Jan. 3, 2023