40 CFR 52.2471 - Classification of regions.

The Washington plan was evaluated on the basis of the following classifications:

Air quality control region	Pollutant					Particulate matter	Sulfur oxides	Nitrogen dioxide	Carbon monoxide	Ozone	Eastern Washington-Northern Idaho Interstate	I	IA	III	III	III	Northern Washington Intrastate	II	III	III	III	III	Olympic-Northwest Washington Intrastate	II	II	III	III	III	Portland Interstate	I	IA	III	III	III	Puget Sound Intrastate	I	IA	III	III	I	South Central Washington Intrastate	I	III	III	III	III

[81 FR 1131, Jan. 11, 2016]