The U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) to protect human health and the environment. EPA evaluates how each area of the country complies with the standard during the process called “area designations,” also referred to as “air quality designations.”
Nearly all Washington counties comply with the NAAQS for sulfur dioxide (SO2). Ecology is currently collecting ambient air monitoring data for three counties in order to determine whether they meet the standard. Based on the preliminary data, an area in Whatcom County is at risk of violating the standard in 2020.
Since we began monitoring SO2
pollution near the Intalco aluminum smelter, we recorded several exceedances of the SO2
standard in 2017 and 2018. With repeated exceedances, the area is at risk of violating the federal standard in 2020, which could lead to EPA designating the area as being in nonattainment. However, we believe that the size of the area impacted may be small based on Ecology’s preliminary air quality modeling analysis and lower SO2
readings at the SO2
monitors at the nearby Phillips 66 and BP refineries.
Nonattainment designation requires the state and local agencies to work together and submit a coordinated plan to EPA on how the area will achieve attainment within a defined timeframe. Failing to do so can trigger mandatory sanctions against the state.
Public health impacts
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 the plant may have been exposed to short-term levels that pose a risk to those with preexisting breathing or health issues. At this time, we have no evidence that elevated levels of SO2 have reached Ferndale or other nearby communities.
We're performing additional analysis and reviewing data from the Phillips 66 and BP SO2
monitors to confirm this. In addition, the Northwest Clean Air Agency recently began operating an SO2
monitor near Eagleridge Elementary School in Ferndale. Information from all of these monitors will be considered in the analysis.
EPA established Air Quality Index (AQI) ratings for SO2
pollution to identify when the air quality becomes unhealthy. The table below provides a summary of number of days in each AQI category in 2017 and in 2018.
Sulfur dioxide levels recorded near the Intalco facility
As we analyze the data and model the distribution of potential impacts, we will know more about which areas pose a concern for air quality. Ecology, which oversees air quality permitting for Intalco, and the Northwest Clean Air Agency (NWCAA), which has overall responsibility for air quality in Whatcom County, may collect additional data to better understand the extent of the SO2
impact in the area. EPA will ultimately determine the nonattainment area boundary.
can also impair visibility in the form of haze and contribute to acid rain.
Timeline for area designation
- Spring 2020: Ecology validates three years of monitoring data
- Spring-summer 2020: Ecology and NWCAA develop a joint recommendation to EPA on whether the area is meeting the standard. If not, the agencies will recommend a boundary for what parts of the county should be designated as being in nonattainment.
- September 2020: EPA is expected to propose an area designation and hold a public comment period.
- December 2020: EPA must finalize the designations.
- March 2021: Designations become effective. For any nonattainment area, the regulatory “clock” to bring the area back into attainment begins.
If part of Whatcom County is designated as being in nonattainment, Ecology and the Northwest Clean Air Agency will develop a plan to reduce emissions and bring the area back into attainment. This plan will be available for public review before submission to EPA. The plan must demonstrate that the area will meet the federal standard by March 2026 (or within 5 years of the effective date of the nonattainment designation).
Ecology and Intalco are exploring air pollution control technology solutions to reduce future SO2
emissions from the facility, including investments in emissions reduction technology, such as installing a wet scrubber.
To learn more or follow the progress, sign up to Ecology’s SO2 attainment email list