(1) To ensure that the program created in RCW 70A.65.060 through 70A.65.210 achieves reductions in criteria pollutants as well as greenhouse gas emissions in overburdened communities highly impacted by air pollution, the department must:

(a) Identify overburdened communities, which may be accomplished through the department's process to identify overburdened communities under chapter 70A.02 RCW;

(b) Deploy an air monitoring network in overburdened communities to collect sufficient air quality data for the 2023 review and subsequent reviews of criteria pollutant reductions conducted under subsection (2) of this section; and

(c)(i) Within the identified overburdened communities, analyze and determine which sources are the greatest contributors of criteria pollutants and develop a high priority list of significant emitters.

(ii) Prior to listing any entity as a high priority emitter, the department must notify that entity and share the data used to rank that entity as a high priority emitter, and provide a period of not less than 60 days for the covered entity to submit more recent data or other information relevant to the designation of that entity as a high priority emitter.

(2)(a) Beginning in 2023, and every two years thereafter, the department must conduct a review to determine levels of criteria pollutants, as well as greenhouse gas emissions, in the overburdened communities identified under subsection (1) of this section. This review must also include an evaluation of initial and subsequent health impacts related to criteria pollution in overburdened communities. The department may conduct this evaluation jointly with the department of health.

(b) Once this review determines the levels of criteria pollutants in an identified overburdened community, then the department, in consultation with local air pollution control authorities, must:

(i) Establish air quality targets to achieve air quality consistent with whichever is more protective for human health:

(A) National ambient air quality standards established by the United States environmental protection agency; or

(B) The air quality experienced in neighboring communities that are not identified as overburdened;

(ii) Identify the stationary and mobile sources that are the greatest contributors of those emissions that are either increasing or not decreasing;

(iii) Achieve the reduction targets through adoption of emission control strategies or other methods;

(iv) Adopt, along with local air pollution control authorities, stricter air quality standards, emission standards, or emissions limitations on criteria pollutants, consistent with the authority of the department provided under RCW 70A.15.3000, and may consider alternative mitigation actions that would reduce criteria pollution by similar amounts; and

(v) After adoption of the stricter air quality standards, emission standards, or emissions limitations on criteria pollutants under (b)(iv) of this subsection, issue an enforceable order or the local air authority must issue an enforceable order, as authorized under RCW 70A.15.1100, as necessary to comply with the stricter standards or limitations and the requirements of this section. The department or local air authority must initiate the process, including provision of notice to all relevant affected permittees or registered sources and to the public, to adopt and implement an enforceable order required under this subsection within six months of the adoption of standards or limitations under (b)(iv) of this subsection.

(c) Actions imposed under this section may not impose requirements on a permitted stationary source that are disproportionate to the permitted stationary source's contribution to air pollution compared to other permitted stationary sources and other sources of criteria pollutants in the overburdened community.

(3) An eligible facility sited after July 25, 2021, that receives allowances under RCW 70A.65.110 must mitigate increases in particulate matter in overburdened communities due to its emissions.

(4)(a) The department must create and adopt a supplement to the department's community engagement plan developed pursuant to chapter 70A.02 RCW. The supplement must describe how the department will engage with overburdened communities and vulnerable populations in:

(i) Identifying emitters in overburdened communities; and

(ii) Monitoring and evaluating criteria pollutant emissions in those areas.

(b) The community engagement plan must include methods for outreach and communication with those who face barriers, language or otherwise, to participation.