Puget Sound Clean Air Agency

Photo: residential chimney smokeWashington State
Opacity Standards

Generating excessive smoke is not only un-neighborly, it's illegal. Under state regulations, smoke from your solid fuel burning device cannot exceed 20 percent opacity for six consecutive minutes. When a burn ban is in effect, it is illegal to generate any visible smoke at all (excluding the first 20 minutes of start-up). Violating smoke emission regulations could result in fines from the Puget Sound Clean Air Agency.

Excessive chimney smoke

Photo: Excessive chimney smoke, three panels, left = 20% (legal), middle = 40% (illegal), right = 80% (aggregious)

20%
(legal)

40%
(illegal)

80%
(egregious)

Additional resources

Washington Administrative Code, Section 173-433-110.

For tips on how to minimize smoke, visit “Burning Basics.”