Pay Online
Sign Up

Sulfur Dioxide (SO2) emissions at Intalco

Apr. 26, 2019

The Northwest Clean Air Agency is working with the Washington Department of Ecology, the U.S. Environmental Protection Agency’s Region 10 based in Seattle, and various stakeholders to bring sulfur dioxide (SO2) emissions from Alcoa’s Intalco aluminum smelter in Whatcom County in line with national air quality standards.

On Dec. 21, 2020, EPA designated a small portion of Whatcom County that includes the Intalco smelter as being in nonattainment of the federal standard.

UPDATE (Sept. 7, 2022): 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, the Washington Department of Ecology and the Northwest Clean Air Agency worked together 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.)

Comment period: Sept. 7 – Oct. 15, 2022

The Department of Ecology invites you to comment on the proposed plan to bring the area back into attainment.

The proposed 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) have participated in the development of the proposed plan.

Submit comments

  • Using the online comment form
  • By mail to Kelsey Holbrook, Department of Ecology, Industrial Section, P.O. Box 47600, Olympia, WA 98504-7600
  • Orally at an online hearing, Oct. 11, 2022, starting at 6 p.m., register and attend

Next steps

EPA’s oversight of the plan is required under the federal Clean Air Act. When the comment period ends, Ecology will review comments received and make appropriate changes before submitting it to EPA. Once approved by EPA, the requirements of the attainment plan and Agreed Order become federally-enforceable.

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

UPDATE (early 2021): In early 2021, the Intalco nonattainment area was put on hold because of the recent change in the Federal Administration. Specifically, a hold was placed, pending review, on recent activities that occurred in the 90-day period prior to the change in administrations. That hold has now been lifted and the nonattainment area work is proceeding on its original schedule. Check Ecology’s Alcoa Intalco webpage for more information.

BACKGROUND: Two air quality monitors near the Intalco smelter have, at times, shown SO2 emissions above the National Ambient Air Quality Standard (NAAQS) of 75 parts per billion. Evidence suggests that the area where periodic exceedances occur is relatively small. But when this occurs a specified number of times within three consecutive years, EPA can designate the area as a nonattainment area, meaning it exceeds the federal standard.

Ecology and the Northwest Clean Air Agency prepared a technical report on their findings and submitted the report to EPA:

On Aug. 21, 2020, EPA proposed a nonattainment area that includes the Intalco facility.  EPA held a public comment period that ended Sept. 21, 2020. EPA had to finalize the designation by Dec. 31, 2020.

(Courtesy image.)

The federal Clean Air Act requires that a nonattainment area include not only the area that is violating the federal pollution standard but also nearby areas that contribute to the violation.

Criteria that factor into determining the boundaries for the nonattainment area include air quality data, emissions information, population density, traffic and commuting patterns, expected growth, weather, topography, jurisdictional boundaries, and control of emissions.

Ecology’s Industrial section has jurisdiction over the Intalco facility, including air emissions. But the proposed nonattainment area’s boundary also includes the Petrogas West facility and some private properties.

Intalco and Ecology (in coordination with other parties, including NWCAA) are required to put together a plan to bring the area back into attainment within a designated time period.

See Ecology’s web pages about SO2 air quality designations and SO2 in general for more information.

About Sulfur Dioxide (SO2) and health

Excess SO2 emissions are a concern because they can impact human health and the environment.

Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. Children, the elderly, and those who suffer from asthma are particularly sensitive to the effects of SO2.

SO2 and other sulfur oxides can react with other compounds in the atmosphere to form small particles, which may penetrate deeply into sensitive parts of the lungs and cause additional health problems.

SO2 and other sulfur oxides also could contribute to acid rain and to visibility-reducing haze on public lands like national parks and wilderness areas.

If you have questions about possible health impacts, call Whatcom County Health at 360-778-6000.