Program Template photo identifier

Air Quality Program

Maintenance Areas

A maintenance area is an area that was designated nonattainment for one of the National Ambient Air Quality Standards (NAAQS), but later met the standard and was re-designated to attainment. To ensure the air quality in this area continues to meet the NAAQS, states are required to develop and implement Maintenance State Implementation Plans. (See Maintenance SIPs page.)

The following areas in Washington have maintenance plans:

NAAQS
Averaging period Concentration

Effective Date Nonattainment Designation

Effective Date Redesignation to Attainment

Affected counties & cities

Contact Lead Agency for information

Ozone
1-hour
0.12 ppm

1/6/1992

6/15/2005

Pierce

PSCAA

Most of King

PSCAA

Part of Snohomish

PSCAA

11/15/1990

6/15/2005

Portland-Vancouver

SWCAA

Carbon Monoxide
8-hour
9 ppm

11/15/1990

10/11/1996

King

PSCAA

Pierce

PSCAA

Snohomish

PSCAA

06/29/2005

Spokane

SRCAA

10/21/1996

Vancouver, WA

SWCAA

12/31/2002

Yakima, WA

YRCAA

PM10
24-hour
150 µg/m3

11/15/1990

5/14/2001

 

Kent, WA

PSCAA

King

PSCAA

Pierce (Tacoma)

PSCAA

12/4/2000

Thurston (Olympia, Tumwater, and Lacey)

ORCAA

8/30/2005

Spokane

SRCAA

9/26/2005

Wallula

Ecology

3/10/2005

Yakima

YRCAA

PM2.5

24-hour

35 µg/m3

12/14/2009 3/12/2015 Tacoma-Pierce County PSCAA

PSCAA: Puget Sound Clean Air Agency
SWCAA: Southwest Clean Air Agency
YRCAA: Yakima Regional Clean Air Agency
ORCAA: Olympic Region Clean Air Agency
SRCAA: Spokane Regional Clean Air Agency


The 1-hour ozone standard was revoked effective June 15, 2005 for all areas in Washington. The Portland-Vancouver and Seattle-Tacoma areas became maintenance areas for the 1-hour ozone NAAQS.

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