Chapter 173-460 WAC – Controls for New Sources of Toxic Air Pollutants

We are starting rulemaking to update Chapter 173-460 WAC, Control for New Sources of Toxic Air Pollutants. Toxic air pollutants, also known as air toxics, are pollutants known or suspected to cause cancer or other adverse health and environmental impacts when emitted in significant quantities. This rule reduces risks from toxic air pollutants by limiting emission concentrations and requiring pollution controls for new and modified commercial and industrial sources.

With this rulemaking, we will consider updating:

  • Emission thresholds, known as acceptable source impact levels (ASILs), used in permitting review of new and modified sources of toxic air pollutants
  • List of toxic air pollutants and establishing multiple averaging times for certain pollutants
  • Process for considering background concentrations of toxic air pollutants during permitting review
  • Rule language about emissions offsets
  • Toxic equivalency factors for certain pollutants
  • Other changes to improve implementation of the rule

Rulemaking timeline

Timeline

Announcement phase (CR-101)

Filing date:
Sept. 16, 2026


Announcement documents

Rule development phase

September 16, 2026 – Early Winter 2028

Public input & involvement

We plan to hold rulemaking meetings starting early 2027. We will update this page with meeting details.

This rulemaking will include an environmental justice assessment, as required by the Healthy Environment for All Act (the HEAL Act, RCW 70A.02.060). We want to engage with communities and Tribes to hear their input and related environmental justice concerns. To get updates about this rulemaking, join our email list.

Additional languages

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Accessibility

To request ADA accommodation for disabilities, or printed materials in a format for the visually impaired, contact Ecology's ADA Coordinator by email at ecyadacoordinator@ecy.wa.gov, or call 360-407-6831. People with impaired hearing may call Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.