1

Attachment C

Oregon State Implementation Plan Revision

Addressing the Interstate Transport of 

Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2),

Lead (Pb) and Fine Particulate Matter (PM 2.5)

Clean Air Act Section 110(a)(2)(D)

May 12, 2015

Air Quality Planning

811 SW 6th Avenue

Portland, OR 97204

Phone: (503) 229-5696

(800) 452-4011

Fax: (503) 229-6762

Contact: Nancy Cardwell

503-229-6610

Nancy Cardwell

www.oregon.gov/DEQ

DEQ is a leader in restoring, 

maintaining and enhancing 

the quality of Oregon’s air, 

land and water.
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Contents

Addressing Interstate Pollutant Impacts under the Clean Air Act...................................3

I. Introduction ..............................................................................................................4

II. Background ...............................................................................................................4

III. Air Quality Data and Attainment Status within the State and Surrounding

States....................................................................................................................5

IV. Nature of Pollutant Transport ................................................................................27

V. Sources of Pollutant Emissions near the State Boundary and Expected 

Impacts in Neighboring States ........................................................................29

VI. Conclusion...............................................................................................................30

Contact:

Nancy Cardwell

Air Planning

(503) 229-6610
3

Addressing Interstate Pollutant Impacts under the Clean Air Act

Overview 

Some amount of air pollution routinely moves across all state borders and across all regions of the country. This 

document addresses the effect of Oregon air emissions transporting to neighboring states. Based on the 

information summarized in the sections that follow, the Oregon Department of Environmental Quality 

concludes that air emissions of nitrogen dioxide (NO2), sulfur dioxide (SO2), lead (Pb), and fine particulate 

matter (PM 2.5) from Oregon sources do not significantly contribute to violations of National Ambient Air 

Quality Standards in other states, or interfere with other states’ efforts to meet air quality standards, prevention 

of significant deterioration (PSD), or protect visibility. DEQ’s conclusions are based on its understanding of air 

pollution problems in adjacent states, and the emission sources, meteorology (weather patterns), and 

topographic features (mountain ranges, etc.) that influence air quality problems in these states. 

DEQ will collaborate with air agencies in Washington, Idaho, Nevada, California and other states whenever 

necessary to evaluate case-specific air quality problems that may involve regional movement of air pollution. 

DEQ’s Clean Air Act section 110 infrastructure SIP provides the framework and legal mechanism for DEQ to 

act as needed to reduce any Oregon emissions found to significantly contribute to air quality problems in other 

states. 

The map below (Figure 1) illustrates the significant distances and mountain ranges that in many areas separate 

Oregon from communities in Washington, California, Idaho, and Nevada and can help limit the long range 

transport of air pollution. 

Figure 1: Map of Oregon and major mountain ranges
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I. Introduction

The interstate transport provision in the CAA section 110(a)(2)(D)(i) (also called “ the good neighbor” 

provision) requires each state to submit a State Implementation Plan (SIP) that prohibits emissions that will 

have certain adverse air quality effects in other states. This SIP submittal is due within three years after the 

Environmental Protection Agency adopts a new or revised NAAQS. 

II. Background

EPA Promulgated NAAQS

 Nitrogen Dioxide (NO2): EPA first set standards for NO2 in 1971; setting both a primary standard 

(to protect health) and a secondary standard (to protect the public welfare) at 53 parts per billion

(ppb), averaged annually. EPA reviewed the standards in 1985 and 1996, deciding to retain the 

standards at the conclusion of each review. In 2005, EPA began another review, resulting in the 

January 22, 2010, rulemaking to establish an additional primary NO2 standard at 100 ppb, averaged 

over one hour (75 FR 6474). 

 Sulfur Dioxide (SO2): Primary standards for SO2 were first set in 1971, at 0.14 parts per million 

(ppm) averaged over a 24-hour period, not to be exceeded more than once per year, and 0.030 ppm, 

annual arithmetic mean. EPA subsequently reviewed the primary standards and determined to retain 

them in 1996. More recently, on June 2, 2010, EPA adopted a revised primary SO2 standard at 75 

ppb, based on a three-year average of the annual 99th percentile of one-hour daily maximum 

concentrations (75 FR 35520). 

 Lead (Pb): On October 15, 2008, the EPA revised the level of the primary and secondary Pb 

NAAQS from 1.5 micrograms per cubic meter (μg/m3) to 0.15 μg/m3. 

 Fine Particulate Matter (PM 2.5): On December 14, 2012 EPA adopted a revised annual NAAQS for 

fine particulate matter (PM 2.5) from 15 μg/m3to 12 μg/m3. 

Section 110(a)(2)(D)(i) of the CAA identifies four distinct requirements related to the impacts of air 

pollutants transported across state lines. It requires that each SIP for a new or revised NAAQS contain 

adequate provisions prohibiting any source or other type of emissions activity within the state from emitting 

air pollutants that may:

1. Contribute significantly to nonattainment of the applicable NAAQS in any other state;

2. Interfere with maintenance of the applicable NAAQS in any other state;

3. Interfere with measures required to be included in the applicable implementation plan for any 

other state to prevent significant deterioration of air quality; and

4. Interfere with measures required to be included in the applicable implementation plan for any 

other state to protect visibility.

Section III below addresses elements 1 and 2 above, contributions to nonattainment of applicable NAAQS, 

and interference with maintenance of applicable NAAQS. Regarding element 3 above (prevention of 

significant deterioration), DEQ’s air permitting rules for industrial sources require analysis for the PSD 
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which ensures that air quality impacts from new or modified industrial sources will not cause or contribute 

to violations of a NAAQS in Oregon or neighboring states, or cause significant visibility impairment in 

federal Class-I areas. EPA most recently approved revisions to Oregon’s PSD program on December 27, 

2011 (76 FR 80747). Regarding element 4 above (visibility protection), Oregon’s federally approved 

regional haze plan provides the mechanism for ensuring emission reductions necessary to achieve visibility 

improvement in Oregon and in neighboring states. EPA approved the first element of the Oregon Regional 

Haze Plan (SIP) including the requirements for best available retrofit technology (BART) (76 FR 38997)

on July 5, 2011. EPA approved the remaining elements of the Oregon Regional Haze SIP on August 22, 

2012 (77 FR 50611).

III. Air Quality Data and Attainment Status within Oregon and Surrounding States

a. Surrounding contiguous states: Oregon is bordered by Washington to the north, the Pacific Ocean 

to the west, California and Nevada to the south, and Idaho to the east. The Snake River separates the 

state from part of Idaho. The Columbia River forms most of the state's northern border. There are six

major sources in Oregon within 5 km of contiguous Washington State and one major source within 5 

km of Idaho. The sources are listed in Tables 5 and 6 below (page 29).

b. Designation of all areas within the state and in each surrounding state (attainment, 

nonattainment, and unclassifiable), including maintenance areas in adjacent states: 

 Nitrogen Dioxide (NO2): On January 20, 2012 EPA designated all areas of the country as 

“unclassifiable/attainment” for the 2010 NO2 NAAQS, including all areas within the states of 

Idaho, California, Nevada, and Washington. The available air quality data show that all 

monitored areas in the country meet the 2010 NO2 NAAQS for 2008-2010. No state or tribe 

recommended an area be designated “nonattainment” during the federal designation process.

 Sulfur Dioxide (SO2): According to EPA, designations for the entire state of Oregon, 

Washington, Idaho, California, and Nevada will be addressed in a future action. See proposed 

Consent Decree, Sierra Club v. McCarthy, No. 3:13-CV-3953-SI (N.D. Cal.), issued March 2, 

2014, 70 Fed. Reg. 31,325, June 2, 2014 found at:

https://federalregister.gov/a/2014-12693

http://content.sierraclub.org/environmentallaw/sites/content.sierraclub.org.environmentallaw/

files/SO2%20Consent%20Decree.pdf

EPA's review of the monitored air quality data from 2009-2011 showed no violations of 2010 1-

hr SO2 standard in any of these states. According to the latest available 2013 Oregon Air Quality 

Data Summaries Report, the downward trend in SO2 emissions continues with the highest 2012 

and 2013 1-hr concentrations under 25 ppb. 

 Lead (Pb): In 2008 EPA designated all areas in the states of Oregon, Idaho, Nevada, and 

Washington as “unclassifiable/attainment.” In California, Los Angeles County South Coast Air 

Basin is classified as “nonattainment.” The rest of the state is designated 

“unclassifiable/attainment.”
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 Fine Particulate Matter (PM 2.5): Shoshone County in Idaho, and Imperial, Fresno, Kings, 

Madera, Merced, San Joaquin, Stanislaus, and Tulare counties in California are designated in 

nonattainment of the 2012 annual PM2.5 standard. There are no nonattainment areas for the 

annual PM 2.5 standard in Oregon, Washington, Idaho, or Nevada. There have been no annual 

PM 2.5 NAAQS violations in SW Washington during the most recent three-year period (2012-

2014). The monitoring network for NO2 and SO2 is presented in Figure 2. The monitoring 

network for PM2.5 and Pb is presented in Figure 3.

c. Monitoring networks for pollutants within the state and surrounding states:

Figure 2: Monitoring network that includes for NO2, and SO2, 

in Oregon

2015 DEQ & LRAPA Real Time Gas

Air Quality Surveillance Network

Portland

Salem

Eugene & 

Springfield

Hermiston

Bend

Medford

Canby

Sauvie 

Island

CO

Sherwood

NO2 & SO2

Ozone
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Figure 3: Monitoring network that includes PM 2.5 and Lead in 

Oregon

2015 DEQ & LRAPA FRM PM 

Air Quality Monitoring Network

Eugene 

Oakridge

La Grande

Burns

Grants 

Pass

Lakeview

Cottage 

Grove

Hillsboro

PM2.5

PM10

PM2.5 

Speciation

Prineville

Medford

Klamath Falls

N. Portland

2 Springfield

SE Portland

Gresham

3

PM10-2.5

PM10 Lead

3

Figure 4: Monitoring networks for NO2 in Washington, Idaho, 

California and Nevada
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Figure 5: Monitoring networks for SO2 in Washington, Idaho, 

California and Nevada

Figure 6: Monitoring networks for Pb in Washington, Idaho, 

California and Nevada
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Figure 7: Monitoring networks for PM 2.5 in Washington, Idaho, 

California and Nevada

d. Ambient data, including the ‘design value’ for pollutants of interest, at each monitoring site

and trends over the last 5-10 years.

Nitrogen Dioxide (NO2):

The level of the hourly NAAQS for NO2 is 100 ppb based on the 98th percentile value from three 

consecutive years of data. The design values shown here are computed for the latest design value period 

using Federal Reference Method or equivalent data reported to EPA by States, Tribes, and local 

agencies. The 2011-2013 design values for NO2 are presented in Table 1. Daily maximum 1-hr NO2 

2000-2013 trends at monitoring stations in Oregon, Washington, California, Idaho, and Nevada are in 

Figures 8-11.

Table 1: County-Level Design Value Concentrations for NO2 1-Hour NAAQS

State County Site 2011-2013 1-hr Design Value (ppb)

California Alameda 060010011 50

California Butte 060070008 37

California Contra 

Costa

060131004 40

California Imperial 060250005 64

California Kern 060296001 46

California Kings 060311004 46

California Los Angeles 060371701 64

California Marin 060410001 45

California Monterey 060531003 35
10

Table 1: County-Level Design Value Concentrations for NO2 1-Hour NAAQS

State County Site 2011-2013 1-hr Design Value (ppb)

California Napa 060550003 39

California Placer 060610006 50

California Riverside 060655001 39

California Sacramento 060670002 43

California San 

Bernardino

060712002 62

California San Diego 060732007 73

California San 

Francisco

060750005 68

California San Joaquin 060771002 53

California San Luis 

Obispo

060798001 38

California San Mateo 060811001 45

California Santa 

Barbara

060831008 36

California Santa Clara 060850005 51

California Solano 060950004 42

California Sutter 061010003 47

California Tulare 061072002 52

California Ventura 061112002 37

California Yolo 061130004 34

Oregon Multnomah 410510080 34

Nevada Washoe 320310016 56
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Figure 8: Trends - Concentrations for NO2 1-Hour NAAQS - Washington

Figure 9: Trends - Concentrations for NO2 1-Hour NAAQS - California
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Figure 10: Trends - Concentrations for NO2 1-Hour NAAQS - Idaho
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Figure 11: Trends – Concentrations for NO2 1-Hour NAAQS - Nevada

Sulfur Dioxide (SO2)

The level of the 1-hour NAAQS for SO2 is 75 ppb calculated as the 3-year average of the 99th percentile 

of the annual distribution of daily maximum 1-hour average concentrations. The 2011-2013 design 

values also calculated as the 3-year average of the annual distribution of daily maximum 1- hr average 

concentrations for SO2 are presented in Table 2. Daily maximum 1-hr SO2 2000-2013 trends at 

monitoring stations in Oregon, Washington, California, Idaho, and Nevada are in Figures 12-16.
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Table 2: County-Level Design Value Concentrations for SO2 1-Hour NAAQS

State County 2011-2013 1-Hour Design Value (ppb)

CA Alameda 15

CA Contra Costa 14

CA Riverside 3

CA Sacramento 2

CA San Bernardino 5

CA San Diego 1

CA San Luis Obispo 21

CA Santa Barbara 36

CA Santa Clara 13

CA Solano 4

ID Caribou 40

NV Clark 8

NV Washoe 6

OR Multnomah 6

WA Clallam 1

Figure 12: Trends – SO2 1-hour NAAQS concentrations – Umatilla 

County, Oregon
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Figure 13: Trends – SO2 1-hour NAAQS concentrations - Washington

Figure 14: Trends – SO2 1-hour NAAQS concentrations - California
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Figure 15: Trends – SO2 1-hour NAAQS concentrations - Idaho

Figure 16: Trends – SO2 1-hour NAAQS concentrations - Nevada
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Lead (Pb):

The level of the 2008 NAAQS for lead is 0.15 μg/m3 not to be exceeded in any 3-month period. The 

2011-2013 available design values for Pb are presented in Table 3. Daily maximum 1-hr Pb 1990-2013 

trends at monitoring stations in Oregon, California, and Idaho are in Figures 17-19.

Table 3. Site-Level Maximum Design Value 

Concentrations for 2008 Lead NAAQS, 2011-2013

State County AQS Site ID 2011-

2013 

Design 

Value 

(μg/m3)

California Imperial 060250005 0.03

California Los Angeles 060371103 0.01

California Los Angeles 060371403 0.11

California Los Angeles 060371405 0.46

California Los Angeles 060371406 0.07

California Los Angeles 060371602 0.01

California Riverside 060651003 0.01

California Riverside 060658001 0.01

California San 

Bernardino

060711004 0.01

California San Diego 060731020 0.17

California San Mateo 060812002 0.33

Oregon Yamhill 410711702 0.05

The design values in bold in Table 3 exceed the 2008 Pb NAAQS. The monitoring site in California is 

800 miles from the Oregon border. Given the great distances involved and the nature of lead transport,

Oregon emissions are not expected to have any effect on lead levels measured in California.

Figure 17 below shows local 2005-2013 Pb trends in Oregon. Figures 18-20 show Pb trends in Idaho,

California and Washington. According to EPA requirements, the lead emissions monitoring threshold is 

0.50 tons per year (tpy). Air quality monitoring agencies are advised to use this threshold to determine if 

an air quality monitor is required to be placed near a facility emitting lead. There are no Pb trends for 

Nevada because Nevada did not conduct ambient monitoring for Pb. The figures show Pb trends in 

Oregon and its neighboring states are going down.
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Figure 17: Annual Maximum 3-Month Average Pb - Oregon

 Lead NAAQS is 0.15 mg/m3 which equals 150 ng/m3

Figure 18: Annual Maximum 3-Month Average Pb - Idaho
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Figure 19: Annual Maximum 3-Month Average Pb - California

Figure 20: Quarterly Maximum Concentrations Pb – Washington
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Fine Particulate Matter (PM 2.5):

The level of the 2012 NAAQS for PM 2.5 is 12 ug/m3 calculated as a 3-year average of the annual 

arithmetic mean. Table 4 presents the 2011-2013 design values for PM2.5. Figures 5-10 present annual

PM2.5 2000-2013 trends at monitoring stations in Oregon, Washington, California, Idaho and Nevada.

Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

California Alameda 060010007 7.6

California Alameda 060010009 10.0

California Butte 060070008 10.1

California Calaveras 060090001 8.4

California Colusa 060111002 7.1

California Contra 

Costa

060130002 7.4

California Fresno 060190011 15.4

California Fresno 060192009 7.8

California Fresno 060195001 16.4

California Fresno 060195025 14.7

California Humboldt 060231002 6.2

California Imperial 60250005 14.3

California Imperial 060250007 7.5

California Imperial 060251003 7.4

California Inyo 060271003 7.5

California Kern 060290014 16.4

California Kern 060290016 17.3

California Kings 060311004 17.0

California Lake 060333001 3.8

California Los 060370002 11.2
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Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

Angeles

California Los 

Angeles

060371002 12.8

California Los 

Angeles

060371103 13.0

California Los 

Angeles

060371201 10.2

California Los 

Angeles

060371302 12.2

California Los 

Angeles

060371602 12.0

California Los 

Angeles

060374002 11.1

California Los 

Angeles

060374004 11.0

California Madera 060392010 18.1

California Marin 060410001 9.5

California Merced 060470003 13.3

California Merced 060472510 11.1

California Monterey 060531003 6.1

California Nevada 060570005 4.6

California Nevada 060571001 7.0

California Orange 060590007 10.7

California Orange 060592022 8.2

California Placer 060610006 7.5

California Plumas 060631006 10.2

California Plumas 060631009 12.2

California Plumas 060631010 12.8

California Riverside 060650009 7.7
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Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

California Riverside 060651003 11.5

California Riverside 060652002 7.7

California Riverside 060655001 6.4

California Riverside 060658001 13.4

California Riverside 060658005 15.1

California Sacramento 060670006 10.4

California Sacramento 060670010 9.5

California Sacramento 060674001 9.3

California San Benito 060690002 5.5

California San 

Bernardino

060710025 12.6

California San 

Bernardino

060712002 12.6

California San 

Bernardino

060718001 8.7

California San 

Bernardino

060719004 11.8

California San Diego 060730001 9.9

California San Diego 060730003 10.6

California San Diego 060731002 10.7

California San Diego 060731010 10.8

California San Diego 060731016 8.7

California San 

Francisco

060750005 9.2

California San Joaquin 060771002 13.8

California San Joaquin 060772010 10.2

California San Luis 

Obispo

060792004 8.7
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Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

California San Luis 

Obispo

060792006 6.6

California San Luis 

Obispo

060792007 11.3

California San Luis 

Obispo

060798001 7.0

California San Mateo 060811001 9.3

California Santa 

Barbara

060830011 9.5

California Santa 

Barbara

060831008 7.6

California Santa Clara 060850002 8.0

California Santa Clara 060850005 10.3

California Santa Cruz 060870007 6.3

California Shasta 060890004 5.7

California Shasta 060893004 6.2

California Siskiyou 060932001 6.3

California Solano 060950004 9.6

California Sonoma 060970003 8.4

California Stanislaus 060990005 13.6

California Stanislaus 060990006 15.7

California Sutter 061010003 7.7

California Tehama 061030006 8.1

California Tulare 061072002 16.6

California Ventura 061110007 9.1

California Ventura 061110009 8.1

California Ventura 061112002 9.1

California Ventura 061113001 9.0
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Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

California Yolo 061131003 7.2

Idaho Ada 160010010 9.1

Idaho Bannock 160050020 7.7

Idaho Benewah 160090010 9.9

Idaho Canyon 160270002 10.8

Idaho Franklin 160410001 8.0

Idaho Lemhi 160590004 12.0

Idaho Shoshone 160790017 12.8

Nevada Clark 320030540 8.1

Nevada Clark 320030561 8.8

Nevada Clark 320031019 4.6

Nevada Washoe 320310016 7.6

Oregon Crook 410130100 9.8

Oregon Harney 410250003 9.5

Oregon Jackson 410290133 10.9

Oregon Josephine 410330114 8.8

Oregon Klamath 410350004 11.6

Oregon Lake 410370001 11.1

Oregon Lane 410390060 7.0

Oregon Lane 410391009 5.8

Oregon Lane 410392013 9.1

Oregon Lane 410399004 7.1

Oregon Multnomah 410510080 8.1

Oregon Umatilla 410590121 7.6

Oregon Washington 410670004 8.2

Washington King 530330057 10.1
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Table 4 PM2.5 Site Listing, 2011-2013 

State County Site ID

2011-

2013 

Annual 

Design 

Value 

(μg/m3)

Washington King 530330080 6.1

Washington King 530332004 7.1

Washington Pierce 530530029 7.8

Washington Snohomish 530610005 5.9

Washington Snohomish 530610020 6.9

Washington Snohomish 530611007 7.7

Washington Spokane 530630021 8.0

Washington Yakima 530770009 9.1

There are design values that exceed the annual PM 2.5 NAAQS in neighboring states at monitoring sites 

located hundreds of miles away from Oregon. Oregon’s PM 2.5 emissions are unlikely to significantly 

contribute to those levels. 

Figure 20 shows annual PM 2.5 2000-2013 NW trends at monitoring stations in Oregon, Washington, 

California, Idaho, and Nevada. The trend shows an 11% regional decrease in PM 2.5 emissions across 

the NW region.

Figure 21 - Annual PM 2.5 2000-2013 NW Trend

Consultation with Neighboring States: In March 2015, DEQ contacted the air quality agencies in neighboring 

states via email - Adele Malone (Nevada), Mike Edwards (Idaho), Sylvia Vanderspek (California), and Paul 
26

Mairose (Washington) - regarding the potential transport of air emissions (NO2, SO2, Pb and PM2.5) across 

state boundaries. They informed DEQ that emissions from Oregon do not appear to be impacting their states in 

a significant way. Specifically, other than wildfires, California is not aware of any Oregon air emissions that 

affect Northern California. Washington’s recent interstate transport report indicates Oregon’s emissions are not 

significantly affecting Washington. Idaho reported that since they do not have a lead, NO2 or SO2 nonattainment area, they do not believe Oregon is affecting Idaho. Due to the lack of any nonattainment or 

maintenance areas for the listed pollutants, Nevada concludes that emissions from Oregon are not currently 

affecting air quality in any significant way. 

IV. Nature and Extent of Expected Pollutant Transport

NO2 and SO2 and Pb normally do not transport over long distances. As NO2 and SO2 can also react in the 

atmosphere to become nitrate and sulfate particulate, both NO2 and SO2 will most likely either disperse in the 

atmosphere or chemically react to form a secondary pollutant within a few miles of the source. Pb would most 

likely be deposited within a few miles of a source. Based on monitoring data and DEQ’s discussion with other 

state air agencies, DEQ concludes that direct emissions of Pb, NO2 and SO2 do not cause or contribute to 

exceedances of the NAAQS. Any impacts from those pollutants as well as PM 2.5 are addressed though DEQ’s 

PSD rules and through the Regional Haze program. 

Nitrogen Dioxide: NO2 is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen 

oxides (NOx)." Other nitrogen oxides include nitrous acid and nitric acid. EPA’s NAAQS uses NO2 as the 

indicator for the larger group of nitrogen oxides. NO2 forms quickly from emissions from cars, trucks and 

buses, power plants and off-road equipment. In addition to contributing to the formation of ground-level ozone, 

and fine particle pollution, NO2 is linked with a number of adverse effects on the respiratory system.

EPA first set standards for NO2 in 1971, setting both a primary standard (to protect health) and a secondary 

standard (to protect the public welfare) at 0.053 parts per billion (ppb), averaged annually. EPA reviewed the 

standards twice since that time, but chose not to revise the annual standards at the conclusion of each review. In 

January 2010, EPA established an additional primary standard at 100 ppb, averaged over one hour. 

Concentrations of NO2 emitted into the atmosphere will decrease during transport through three mechanisms: 

deposition, chemical transformation, and dispersion. Interstate transport of NO2 is not a concern for Oregon due 

to the distances involved for large stationary sources and large concentrations of area source emissions in 

western Oregon. 

Sulfur Dioxide: SO2 is one of a group of highly reactive gasses known as “oxides of sulfur.” Generally the 

largest sources of SO2 emissions are from fossil fuel combustion at power plants (73%) and other industrial 

facilities (20%). Smaller sources of SO2 emissions include industrial processes such as extracting metal from 

ore, and burning high sulfur containing fuels in locomotives, large ships, and non-road equipment. SO2 is linked 

with a number of adverse effects on the respiratory system. The emission inventory for Oregon demonstrates a 

similar source distribution. 

EPA first set standards for SO2 in 1971. EPA set a 24-hour primary standard at 140 ppb and an annual average 

standard at 30 ppb (to protect health). EPA also set a 3-hour average secondary standard at 500 ppb (to protect 

the public welfare). In 1996, EPA reviewed the SO2 NAAQS and chose not to revise the standards. In 2010, 

EPA revised the primary SO2 NAAQS by establishing a new 1-hour standard at a level of 75 ppb. EPA revoked 

the two existing primary standards because they would not provide additional public health protection.
27

Concentrations of SO2 emitted into the atmosphere decreases during transport through three mechanisms: 

deposition, chemical transformation, and dispersion. Interstate transport of SO2 is not a concern for Oregon due 

to the distances involved for large stationary sources and large concentrations of area source emissions in 

western Oregon. 

Lead: As noted in the EPA’s October 14, 2011 Pb infrastructure guidance, the physical properties of Pb prevent 

emissions from experiencing the same travel or formation phenomena as fine particulate matter or ozone. More 

specifically, there is a sharp decrease in Pb concentrations, at least in the coarse fraction, as the distance from a 

Pb source increases. Accordingly, while it may be possible for a source in a state to emit Pb in a location and in 

quantities that may contribute significantly to nonattainment in, or interfere with maintenance by, any other 

state, EPA anticipates that this would be a rare situation (e.g., where large sources are in close proximity to state 

boundaries). EPA’s experience with initial Pb designations suggests that sources that emit less than 0.5 tons per 

year or that are located more than two miles from a state border generally appear unlikely to contribute 

significantly to nonattainment in another state. All sources of Pb emissions in Oregon are below 0.5 tons per 

year and are located greater than two miles from the state border. Therefore, it is unlikely that sources in 

Oregon will significantly contribute to nonattainment or interfere with maintenance of the 2008 Pb NAAQS in 

any other state.

Fine Particulate Matter: DEQ’s consultation with air agencies in adjacent states suggests that high PM 2.5

levels in their respective communities are driven largely by local pollution sources during air stagnation events. 

Local air stagnation events would generally preclude interstate air pollution transport as a significant contributor 

to high PM 2.5 levels jeopardizing NAAQS compliance. 

V. Sources of Pollutant Emissions Near the State Boundary and Expected Impacts in 

Neighboring States.

This section addresses sources and emissions for pollutants (specifically major point or area source emissions

and their proximity to the state boundary) and the likelihood that emissions from these sources would transport 

across the state boundary to contribute significantly to nonattainment or interfere with maintenance of any 

applicable NAAQS in any other state. 

There are six Title V Oregon sources (major industrial sources that have a potential to emit a 100 tons per year 

of any criteria pollutant) in close proximity to the Washington border and one source in close proximity to the 

Idaho border. 

Table 5: Closest Sources within 5 km of Washington Border

Source Name City NOX PB PM25 SO2 Washington 

(km) 

Georgia-Pacific Consumer Products LP CLATSKANIE 1,062.2 0.0 951.4 706.7 1

Owens-Brockway Glass Container Inc. PORTLAND 406.5 0.0 47.6 119.0 4

Cascades Tissue Group-Oregon SAINT HELENS 247.3 0.0 9.1 2.1 1

EVRAZ Inc, NA PORTLAND 192.9 0.1 24.5 4.1 3

Portland General Electric Company Beaver Plant/Port Westward I Plant CLATSKANIE 91.9 0.0 35.6 13.6 1

Portland General Electric Company Coyote Springs Plant BOARDMAN 79.9 0.0 13.8 3.1 1

2011 Actual Emissions (tpy)
28

Georgia-Pacific Consumer Products LP, Cascades Tissue Group-Oregon, Portland General Electric Company 

Beaver Plant/Port Westward I Plant, and Portland General Electric Company Coyote Springs Plant all went 

through PSD analysis, were issued PSD permits and thus demonstrated that their emissions do not cause or 

contribute to a violation of any applicable NAAQS.

Owens-Brockway Glass Containers and Evraz were evaluated as part of the competing sources inventory during 

both Port Westward and Troutdale Energy Center’s PSD analyses and thus demonstrated that their emissions 

considered in conjunction with the emissions from other sources in the area do not cause or contribute to a 

violation of any applicable NAAQS. 

A PSD permit applicant must conduct an air quality analysis of the ambient impacts associated with the 

construction and operation of a proposed new source or modification. The purpose of the air quality analysis is 

to demonstrate that new emissions from a proposed major stationary source or major modification, in 

conjunction with other applicable emissions from existing sources (including secondary emissions), will not 

cause or contribute to a violation of any applicable NAAQS. 

Portland General Electric’s coal-fired power plant is located in Boardman, Oregon, 14 km south of 

Washington’s border. It is the only coal fired power plant in Oregon. In December 2010, the Environmental 

Quality Commission approved DEQ's proposed revisions to air pollution control rules for this plant. Based on 

the adopted rules, Boardman has a federally enforceable shutdown date of December 31, 2020. The rules also 

require PGE Boardman to use dry sorbent injection controls to meet federal regulations for sulfur dioxide 

control and a more stringent sulfur dioxide limit from 2018-2020. DEQ concluded that the proposed BART 

controls, when combined with the permanent closure of plant no later than December 31, 2020, meet federal 

requirements and provide a significant environmental and public health benefit. 

Based on the analysis discussed above, it is reasonable to conclude that emissions from sources in Oregon do 

not significantly contribute to PM2.5 and NO2 concentrations in any other state.

Regional Work with Western Regional Air Partnership (WRAP): In late 2010, WRAP initiated the West-wide 

Jump-start Air Quality Modeling Study (WestJumpAQMS). The goal of the study was to develop the next 

generation of regional air quality modeling databases for ozone, PM2.5, visibility and deposition planning in the 

western U.S and to provide information on the role of interstate and international transport to ozone and PM2.5

under current and potential future NAAQS. The study looked at PM2.5 annual source apportionment but did not 

look at the transport of lead, NO2 or SO2. DEQ reviewed Appendix E, State Contributions to Modeled Annual 

PM 2.5 Concentrations in 2008 by Monitoring Site, and the total annual PM2.5 modeled concentrations in all the 

counties in the state of Washington, California, Idaho, Nevada, and as far away as Wyoming. Clark and 

Skamania counties in Washington may be impacted by Oregon’s PM2.5 emissions from Georgia Pacific 

Consumer Products located in Clatskanie. However, Washington does not have an annual PM2.5 nonattainment 

area and has not had any violations of the PM2.5 NAAQS in the past 3 years. Any potential impact does not 

result in Oregon’s contribution to nonattainment or violations of annual PM2.5 standard in the state of 

Washington. The impacts by Oregon to other neighboring states were insignificant.

Table 6: Closest Sources within 5 km of Idaho Border but NOX emissions less than 100 tons 2011 Actual Emissions (tpy)

Source Name City NOX PB PM25 SO2 Idaho (km)

The Amalgamated Sugar Company LLC NYSSA 1.0 0.0 0.0 1.0 1
29

VI. Conclusion

In general air pollution from all sources transport across state boundaries. Based on the information described 

above (Oregon’s emissions inventory, air monitoring data and consultation with neighboring state air agencies),

DEQ finds no evidence to suggest that Oregon emission of NO2, SO2, Pb and PM2.5 significantly contribute to 

exeedances or violations of NAAQS, or cause adverse effects in the neighboring states. Additionally, Oregon’s 

PSD program requires NAAQS and visibility analysis for any new or modified industrial sources. 

In conclusion, Oregon’s SIP complies with CAA Section 110(a)(2)(D)(i)(I). The current Oregon SIP contains 

adequate provisions prohibiting any source or other type of emissions activity within the State from emitting 

any air pollutant in amounts that will contribute significantly to nonattainment in, or interfere with maintenance 

by, any other State with respect to any such national primary or secondary ambient air quality standard.