Washington State 

Implementation Plan Revision

Interstate Transport of Fine Particulate 

Matter

March 2015 

Publication no: 15-02-006
Publication and Contact Information

This report is available on the Department of Ecology’s website at 

https://fortress.wa.gov/ecy/publications/SummaryPages/1502006.html

For more information contact:

Air Quality Program

P.O. Box 47600 

Olympia, WA 98504-7600 

Phone: 360-407-6783 

Washington State Department of Ecology - www.ecy.wa.gov

o Headquarters, Olympia 360-407-6000

o Northwest Regional Office, Bellevue 425-649-7000

o Southwest Regional Office, Olympia 360-407-6300

o Central Regional Office, Yakima 509-575-2490

o Eastern Regional Office, Spokane 509-329-3400

If you need this document in a format for the visually impaired, call the Air Quality 

Program at (360) 407-6000. Persons with hearing loss can call 711 for Washington Relay

Service. Persons with a speech disability can call 877-833-6341.
Interstate Transport of Fine Particulate 

Matter 

Addressing requirements for the 2006 24-hour 

National Ambient Air Quality Standard

 by

Air Quality Program

Washington State Department of Ecology

Olympia, Washington
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Table of Contents

Page

List of Figures and Tables................................................................................................... ii

Figures........................................................................................................................... ii

Tables............................................................................................................................ ii

Acknowledgements............................................................................................................ iii

Executive Summary.............................................................................................................v

Introduction......................................................................................................................... 1

Background ................................................................................................................... 1

Washington’s approach................................................................................................. 3

Factors impacting transport of PM2.5 .................................................................................. 4

Topography, meteorology and relevant sources............................................................ 4

Western Washington............................................................................................. 5

Eastern Washington .............................................................................................. 6

Emissions Inventory...................................................................................................... 7

Interstate Transport Technical Assessment......................................................................... 9

Nonattainment and Maintenance Receptor Selection Methodology ............................. 9

Factors considered in the Transport Analysis ............................................................. 11

Transport Assessment for Nonattainment Receptors ........................................................ 13

Idaho ........................................................................................................................... 13

Lemhi County (Salmon) ..................................................................................... 15

Franklin County (Franklin)................................................................................. 15

Shoshone County (Pinehurst) ............................................................................. 15

Oregon......................................................................................................................... 16

Crook County (Prineville)................................................................................... 16

Klamath County (Klamath Falls)........................................................................ 18

Jackson County (Medford) ................................................................................. 19

Lake County (Lakeview) .................................................................................... 19

Lane County (Oakridge)..................................................................................... 20

Appendices.......................................................................................................................... 1

Appendix A. IMPROVE PM2.5 data for the period 2009-2013.................................... 1

Appendix B. PM2.5 data for the period 2009-2013....................................................... 1

i
List of Figures and Tables

Page

Figures

Figure 1 Average annual precipitation in Washington.................................................................... 4

Figure 2 Summary of NOx emissions for the year 2011 for the state of Washington..................... 7

Figure 3 Summary of SO2 emissions for the year 2011 for the state of Washington...................... 7

Figure 4 Summary of PM2.5 emissions for the year 2011 for the state of Washington. .................. 8

Figure 5 Map of receptors and IMPROVE sites used in this analysis .......................................... 12

Figure 6 Sequence of MODIS satellite images on September 20 (left) and 21 (right), 2012........ 14

Figure 7 MODIS satellite images for August 13 (left) and August 23 (right), 2012. ................... 14

Figure 8 Composition of PM2.5 at Columbia River Gorge station ................................................ 17

Figure 9 Correlation between wind speed and PM2.5 at Prineville, OR (hourly data)................... 18

Tables

Table 1 Anthropogenic source categories of PM2.5 Emission in WA (2005 EI, Ecology).............. 8

Table 2 Design values for nonattainment receptors for the 2006 24-hour NAAQS ..................... 10

Table 3 IMPROVE sites................................................................................................................ 11

ii
Acknowledgements

The authors of this report would like to thank the following people for their contribution to this

study:

• Anya Caudill

• Clint Bowman

• Ranil Dhammapala

• Jocelyn Jones

• Amber Littlejohn

• Jeff Hunt

iii
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iv
Executive Summary

The “good neighbor” or “interstate transport” provisions of the Federal Clean Air Act (CAA)

protect downwind states from harmful pollution that originates in upwind states. This State

Implementation Plan (SIP) revision document contains Washington’s analysis of the interstate

transport of fine particles (PM2.5). It finds that Washington’s sources do not significantly

contribute to PM2.5 air pollution in other states. No new rules are proposed.

Exposure to PM2.5 is associated with respiratory diseases, decreased heart and lung function,

asthma attacks, heart attacks, strokes and premature death. In 2006, Environmental Protection

Agency (EPA) strengthened the National Ambient Air Quality Standards (NAAQS) for PM2.5.

The revised 2006 standard triggered the requirement to assess Washington’s contributions to

areas with PM2.5 concerns in neighboring states.

PM2.5 are particles of 2.5 micrometers in diameter or smaller. PM2.5 is emitted in combustion

processes (e.g. wood stoves, fireplaces, exhaust from vehicles, ships and trains, and industrial

processes), or can also be formed in the atmosphere from other elements and compounds, for

example nitrogen oxides and sulfur dioxides. PM2.5 can be transported and dispersed over

hundreds of miles depending on the weather, wind patterns, and terrain and water features.

Ecology reviewed existing monitoring data, emissions inventories, topography and meteorology,

technical support documents, and the latest design values to establish potential “red flags”

indicative of a significant PM2.5 transport to neighboring states. Ecology’s findings are similar

for all areas of PM2.5 concern in neighboring states. Stagnation events in combination with

localized sources — particularly wood smoke from residential heating activities — are the most

common factors resulting in high levels of PM2.5.

Significant distance between state borders and the areas of PM2.5 air quality concerns in other

states further supports that transport from Washington sources is unlikely to contribute

significantly to these episodes. Only one exceedance in St. Luke’s Meridian (ID) was traced

back to a Washington wildfire. The 2012 National Interagency Coordination Center (NICC)

annual report identified lightning as the cause of this particular wildfire. As a natural event, it

could not be reasonably controlled or prevented.

Ecology found no evidence of significant transport of PM2.5 pollution across the state border.

Ecology concludes that it is safe to assume that Washington sources do not contribute

significantly to PM2.5 pollution in any other state.

v

Introduction

Washington State Department of Ecology (Ecology) submits this State Implementation Plan

(SIP) revision to address the requirements of the Clean Air Act (CAA) with regard to the 2006

24-hour (PM2.5) National Ambient Air Quality Standard (NAAQS). This revision addresses

section 110(a)(2)(D)(i) of the CAA that requires a SIP to:

(D) contain adequate provisions –

(i) prohibiting, consistent with the provisions of this subchapter, any source or

other type of emissions activity within the State from emitting any air pollutant

in amounts which will –

(I) 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....

(II) interfere with measures required to be included in the applicable

implementation plan for any other state....to prevent significant

deterioration or to protect visibility

The requirements to control interstate transport of pollutants are often referred to as “good

neighbor” provisions of the CAA. The intent of the provisions is to ensure that residents and the

welfare of downwind states are protected from harmful emissions originating in upwind states.

The Washington SIP, codified in 40 CFR 52 Subpart WW, prohibits any source or type of

emissions within the state from significantly contributing to nonattainment or interfering with

maintenance in another state. The analysis developed by Washington in support of this SIP

revision showed no indication of a significant PM2.5 transport across state borders. Based on our

assessment and findings, we assert that Washington does not contribute significantly to

nonattainment, or interfere with maintenance, in another state with respect to the PM2.5 NAAQS.

Background

Particulate matter is one of the “criteria pollutants” for which EPA has promulgated NAAQS

under the CAA. In particular, fine particulate matter, or PM2.5, describes particulate matter that

is 2.5 micrometers in diameter and smaller. Primary fine particles are directly emitted by

sources, while secondary fine particles form in the atmosphere from gases emitted by sources.

Sulfur dioxide (SO2), ammonia (NH4), and nitrogen oxides (NOX) are the precursors for

ammonium bisulfate ((NH4)HSO4), ammonium sulfate ((NH4)2SO4), and ammonium nitrate

(NH4NO3) particles that often constitute major fractions of PM2.5. Volatile Organic Compounds

(VOC) may also contribute to Secondary Organic Aerosol (SOA).

1
The nation’s air quality standards for particulates were first established in 1971 (measured Total

Suspended Particulates) and were not significantly revised until 1987, when the U.S.

Environmental Protection Agency (EPA) established the PM10 NAAQS. In 1997, for regulatory

purposes, EPA decided to separate particles into PM2.5 and PM10 because of the differing health

effects. The primary and secondary NAAQS for PM2.5 were set as 65 μg/m3 averaged over a 24-

hour period, and an annual concentration of 15 μg/m3 based on a three year average of the annual

arithmetic mean PM2.5 concentration from one or more community-oriented monitors. On

September 21, 2006, EPA revised the 24-hour standard for PM2.5 from 65 μg/m3 to 35 μg/m3,

and retained the annual fine particle standard at 15 μg/m3 (71 FR 61144).

Under sections 110(a)(1) and (2) of the CAA, within three years of the promulgation of the new

standards, states are required to submit a SIP revision providing for the implementation,

maintenance, and enforcement of the new standards. The SIP revision was due in October 2009.

Due to limited resources and competing priorities, Washington missed the deadline.

On May 28, 2010, EPA notified certain states and territories (including Washington) that they

have failed to meet CAA deadlines for submitting SIP revisions satisfying section 110(a)

nonattainment and maintenance transport requirements for the 2006 24-hour PM2.5 NAAQS. In

the Federal Register Notice published on July 9, 2010 (75 FR 32673), EPA issued a finding of

failure to submit this SIP. This finding started a 2-year deadline for the promulgation of a

Federal Implementation Plan (FIP) by EPA unless, prior to the deadline, a state makes a

submission and EPA approves such submission. The finding did not trigger a sanction clock.

For the eastern part of the continental United States, EPA developed a regional air quality

modeling analysis and promulgated two rules: 2005 Clean Air Interstate Rule (CAIR) and its

replacement 2011 Cross-State Air Pollution Rule (CSAPR). Both rules were challenged in

courts and the Transport Rule was vacated in August 2012. In the meantime, CAIR continued to

be implemented. In September 4, 2013, the U.S. Supreme Court reversed the D.C Circuit

opinion that vacated CSAPR and in June 26, 2014, the U.S. government filed a motion with the

U.S. Court of Appeals for the D.C. Circuit to lift the stay of the CSAPR. The court is

considering the motion and in the meantime, CAIR remains in place.

In September 2009, EPA issued a Guidance on SIP Elements Required Under Section 110(a)(1)

and (2) for the 8-hour Ozone and PM2.5 NAAQS (Harnett Guidance). In this guidance, EPA

directed states to develop an adequate technical analysis to support state’s findings and

conclusions. In regards to the contribution to nonattainment requirement, the guidance stated:

Information to support state’s determination with respect to significant

contribution to nonattainment might include, but is not limited to, information concerning

emissions in the state, meteorological conditions in the state and the potentially impacted

states, the distance to the nearest area that is not attaining the NAAQS in another state,

and air quality modeling.

2
With respect to the interference with maintenance requirement, the guidance stated:

A state’s submission for the requirement should provide the technical information

with the state deems appropriate to support its conclusions. Suitable information might

include, but is not limited to, information concerning emissions in the state and the

potentially impacted states, monitored ambient concentrations in the state and the

potentially impacted states, and air quality modeling.

The transport and dispersion of air pollutants in the ambient air are influenced by many complex

factors such as global and regional weather and climate patterns, topography, and location of

emission sources. In general, the concentration of the pollutant decreases as it travels from the

point of release and is dispersed by wind and other natural phenomena. Air quality modeling is

the best tool to estimate the amount of pollutants transported regionally. Such modeling requires

significant technical resources which are not currently available at the state level.

The regional modeling performed originally for CAIR assists the Eastern states in understanding

interstate transport of PM2.5. No such modeling is available for the Western States, which are

responsible for developing each their own technical analysis and methodology to support their

findings.

Washington’s approach

In the absence of a regional-scale modeling specifically for PM2.5 transport in Western states,

Washington’s approach was to assess existing data and relevant factors for potential “red flags”

indicative of a significant PM2.5 transport. Ecology felt this approach was warranted due to the

following factors:

• Washington did not receive notification from any other state or EPA indicating that

Washington sources significantly contribute to nonattainment or interfere with maintenance

of the PM2.5 NAAQS in those states.

• The Western part of the U.S. does not have PM2.5 transport problems to the extent

comparable to the Eastern states, for which regional modeling is available.

As part of this analysis, Ecology reviewed:

• Washington’s topography, meteorology and sources related.

• Current and projected PM2.5 precursors’ emission inventory for the state.

• Technical Support Documentation for the PM2.5 in nonattainment areas as well as for

interstate transport in surrounding states.

• Latest design values for Oregon and Idaho counties neighboring Washington.

Factors impacting transport of PM2.5 such as topography, meteorology, and regional sources are

reviewed in the following section. A revision of the current and projected emission inventories

of precursors for the state of Washington is included, as well. The technical assessment and the

ambient data supporting our conclusions are presented in the last section and Appendices,

respectively.

3
Factors impacting transport of PM2.5

Topography, meteorology and relevant sources1

The State of Washington is located on the windward Pacific coast. The climatic elements

combine to produce a predominantly marine-type climate west of the Cascade Mountains and a

mixed continental and marine climate east of the Cascades. Considering its northerly latitude,

46° to 49°, Washington’s climate is mild.

There are several climatic controls which have a definite influence on the climate: (a) terrain, (b)

Pacific Ocean, and (c) semi-permanent high and low pressure regions located over the North

Pacific Ocean. The effects of these controls combine to produce entirely different conditions

within short distances.

The Cascade Mountains, 90 to 125 miles inland and 4,000 to 10,000 feet in elevation, are a

topographic and climatic barrier separating the state into eastern and western Washington. The

wet season begins in October, reaches a peak in winter, and then gradually decreases in the

spring. High peaks in the Cascades are snowcapped throughout the year. The Columbia River,

draining approximately 259,000 square miles in the Pacific Northwest and second only to the

Mississippi River in volume flow, enters near the northeastern corner of the state and flows in a

semi‐circular pattern through eastern Washington. Before reaching the Pacific Ocean, it drains

all of eastern Washington and the western slope of the Cascade Mountains between Mt. Rainier

and the Oregon border.

Figure 1 Average annual precipitation in Washington.2

Reservoirs on the windward slopes of the mountains provide an abundance of water for

metropolitan areas, and hydroelectric projects have been developed along several rivers.

Hydroelectricity supplies about two thirds of Washington’s electricity requirements.

1 Adapted from 2010 Washington State Ambient Air Monitoring Network Assessment, publication no. 10-02-016 and

Climate of Washington, Western Regional Climate Center, (www.wrcc.dri.edu/narratives/WASHINGTON.htm) 2 Adapted from http://www.wrcc.dri.edu/pcpn/wa.gif

4
The mountainous areas over the entire state and a major portion of the lowlands west of the

Cascades are covered by timber. Species include both conifers (Douglas fir, spruce, hemlock,

cedar) and deciduous (big leaf maple and alder). A dense undergrowth of fern and moss is found

in the rainforest on the Olympic Peninsula. The lower elevations in eastern Washington consist

of open stands of Ponderosa pine. Logging and other forest management practices are major

activities in these areas.

The Washington State Department of Natural Resources regulates silvicultural burning, while

Ecology and the local air agencies regulate agricultural and other outdoor burning.

Western Washington

West of the Cascade Mountains, summers are cool and comparatively dry, and winters are mild,

wet, and cloudy. Snowfall is light in the lower elevations and heavy in the mountains. In the

interior valleys, measurable rainfall is recorded on 150 days each year and on 190 days in the

mountains and along the coast. During July and August, the driest months, it is not unusual for

two to four weeks to pass with little or no precipitation. However, during the wettest months

November and December, precipitation is frequently recorded on over 20 days each month.

The highest summer and lowest winter temperatures are usually recorded during periods of 

easterly winds. Agriculture is confined to the river valleys and well‐drained areas in the

lowlands. Although the Cascade Range divides the state into two major climatic regions, there

are several climatic areas within each of these regions:

• The West Olympic Coastal area includes the coastal plains and the western slope of the

coastal range from the Columbia River to the Strait of Juan de Fuca. This area receives the

full force of storms moving inland from over the ocean, thus heavy precipitation and gale

force winds occur frequently during the winter season. The “rainforest” area along the

southwestern and western slopes of the Olympic Mountains receives the heaviest

precipitation in the continental United States, with annual precipitation exceeding 150 inches

along the windward slopes. Air pollution sources in this sparsely populated area include a

few industries, outdoor/ silvicultural burning, and smoke from woodstoves and other home

heating devices in some communities.

• The Northeast Olympic‐San Juan Islands area includes the lower elevation along the

northeastern slope of the Olympic Mountains extending eastward along the Strait of Juan de

Fuca from near Port Angeles to Whidbey Island and then northward into the San Juan

islands. The area is shielded from winter storms moving inland from the ocean by the

Olympic Mountains and the extension of the Coastal Range on Vancouver Island. This belt

in the “rain shadow” of the Olympic Mountains is the driest area in western Washington.

The coldest weather is usually associated with outflows of cold air from the interior of

Canada. The few air quality concerns in the area are mostly caused by smoke from

woodstoves and other home heating devices in larger communities, outdoor burning, and by

some industrial facilities.

5
• The Puget Sound Lowlands area includes a narrow strip of land along the west side of Puget

Sound southward from the Strait of Juan de Fuca to the vicinity of Centralia and Chehalis

and a somewhat wider strip along the east side of the Sound extending northward to the

Canadian Border. Variations in the temperature, length of the growing season, fog, rainfall,

and snowfall are due to such factors as distance from the Sound, the rolling terrain, and

influx of air from the ocean through the Strait of Juan de Fuca and the Chehalis River

valley. Most of this area is near the eastern edge of the rain shadow of the Olympic

Mountains. The prevailing wind direction is south or southwest during the wet season and

northwest in summer. This is the most densely populated and industrialized area in the state.

Vehicular, industrial, domestic, and marine sources (shipping, ferries), and both vessels and

traffic at ports are among the main anthropogenic sources in the area. Summertime PM2.5

concentrations are usually low due to sufficient atmospheric mixing, but PM2.5 can be 

elevated under conditions of clear skies, light wind and a sharp temperature inversion during

the home heating season (October – March) when woodstoves and other heating devices are

typically used. Some sheltered locations (such as Darrington, Kent, and the Duwamish 

valley) can experience a buildup of pollutants even when most other areas are moderately 

ventilated. Some areas with a high density of woodstove use (South Tacoma, Marysville,

Lynnwood, Darrington, and Bremerton) frequently experience rapid rises of PM2.5 levels in

the home heating season, during periods of poor dispersion.

Eastern Washington

This section of the state is part of the large inland basin between the Cascade and Rocky

Mountains. East of the Cascades, summers are warmer, winters are colder, and precipitation is

less than in western Washington. The major agricultural areas are in eastern Washington.

During most of the year, the prevailing direction of the wind is from the southwest or west. The

frequency of northeasterly winds is greatest in the fall and winter. Melting snow provides

irrigation water for orchards and other agricultural areas in the Okanogan, Wenatchee, Methow,

Yakima, and Columbia River valleys. Dry land farming practices are generally followed in the

small‐grain growing areas.

• The Okanogan-Big Bend area includes fruit‐producing valleys along the Okanogan, Methow,

and Columbia rivers, grazing land along the southern Okanogan highlands, the Waterville 

Plateau, and part of the channeled scablands. Major air pollution sources are outdoor burning

(year round, except during summer fire safety burn bans), agricultural burning (spring and

fall burn seasons), orchard heaters, smudge pots, silvicultural burning, and woodstove use.

In rare instances, smoke from some burns may become entrained in evening downslope flow

and settle in sheltered valleys (examples include Wenatchee, Twisp, Winthrop, Omak, and

Leavenworth). Smoke from any combination of these sources, if coupled with a strong

temperature inversion and calm conditions, often result in elevated PM2.5 concentrations.

• The Central Basin area includes the Ellensburg valley, the central plains area in the

Columbia Basin south from the Waterville Plateau to the Oregon border and east to near the

Palouse River. This is the lowest and driest section in eastern Washington. Wheat and

barley are the most widely grown crops in this area, while alfalfa, lentils and potatoes are

also grown on a smaller scale. Agricultural and outdoor burns are the main PM2.5

6
sources. Except for the larger populated cities of Spokane, the Tri Cities, Ellensburg and

Walla Walla, smoke from home heating devices and prescribed burning is not a major

concern in this sparsely populated area. Tilling operations, windblown dust and re‐

suspended road dust sometimes gives rise to elevated levels of PM10.

Emissions Inventory

Ecology reviewed data published from the NEI 20113 for the main PM2.5 precursors. Figure 1

and 2 present emissions by sector and emission density maps for NOx and SO2 for the state of

Washington:

Figure 2 Summary of NOx emissions for the year 2011 for the state of Washington.

Figure 3 Summary of SO2 emissions for the year 2011 for the state of Washington.

3 EPA website, Air Emission Sources, State and County Emission Summaries (http://www.epa.gov/cgibin/broker?_service=data&_debug=0&_program=dataprog.state_1.sas&pol=NOX&stfips=53)

7
In addition, Ecology reviewed PM2.5 emissions for the year 2011 as well as the statewide

emission inventory developed by Ecology in 2005. Figure 3 shows PM2.5 emissions by sector

and emission density map:

Figure 4 Summary of PM2.5 emissions for the year 2011 for the state of Washington.

Table 1 lists anthropogenic source categories used in the 2005 EI. Asphalt paving, pesticide

usage, fugitive emissions from construction sites, fugitive emissions from agricultural

windblown dust, land clearing burning, and aircraft emissions were not included in the Ecology’s

2005 EI.

Table 1 Anthropogenic source categories of PM2.5 Emission in WA (2005 EI, Ecology)

Source Category Emissions

(Tons per year)

Woodstoves, fireplaces, inserts 14,544

Agricultural tilling and harvesting 13,118

Industrial, commercial or institutional sources (point sources) 5,773

Others

Paved and unpaved road dust 4,891

Land-based non-road

mobile(except locomotives) 3,865

Agricultural, silvicultural and

rangeland burning 3,698

Residential outdoor burning: yard

waste, trash 3,167

On-road mobile sources 2,711

Commercial marine vessels 1,440

Locomotives 583

Recreational boats 368

Residential fuel use(natural gas,

oil, propane, butane) 362

According to Table 1, woodstoves, fireplaces and inserts are responsible for about a quarter

(27%) of all primary PM2.5 emissions in the state. They are closely followed by agricultural

8
tilling and harvesting (24%). The third largest group category for primary PM2.5 emissions is

point sources (11%).

Finally, Ecology also reviewed the emission inventories used in the CSAPR modeling analysis4.

The 2005 base case used in the CSAPR analysis included values for NOx and SO2 emissions of

357,674 tons and 57,580 tons, correspondingly. The NOx and SO2 values for Washington in

2012 are 268,870 tons and 38,581 tons, indicating that Washington’s emissions were reduced by

24.8% and 33%, respectively.

Interstate Transport Technical Assessment

Consistent with previous EPA’s approach followed in the 1998 NOx SIP call, the 2005 CAIR

and the 2011 Transport Rule5, the following analysis evaluates the impact of Washington on

specific monitors in neighboring states that have been identified as having nonattainment and/or

maintenance areas, which are referred to as “receptors”.

Nonattainment and Maintenance Receptor Selection

Methodology

For this analysis, a receptor may be a downwind location that is currently violating the PM2.5

NAAQS, has violated in the past, is projected to violate in the future, or may have trouble

maintaining the NAAQS in the future. The nonattainment and maintenance receptors identified

here were selected based on recent ambient air quality monitoring data.

The particular ambient data analyzed spanned a period of 5 years to allow examination of the

year to year variability. The three most recent consecutive official three-year design value

periods available6 are 2009-2011, 2010-2012, and 2011-2013, and were used to identify

receptors relevant to this analysis. The particular selection criteria for both nonattainment and

maintenance receptors are described below7

:

• A nonattainment receptor is defined as a monitoring site that is violating the NAAQS in the

most recent three-year period (i.e. 2011-2013).

• A maintenance receptor is defined as a monitoring site that shows attainment in the most

recent three year design value period (i.e. 2011-2013) but violated the NAAQS in at least one

of the previous two design value periods (i.e. 2009-2011 and/or 2010-2012).

4 See Emissions Inventory Final Rule TSD, Technical Support Document (TSD) for the final Transport Rule, Docket

ID No. EPA-HQ-OAR-2009-0491, June 28, 2011, at Tables 7-1 and 7-2 5

See NOx SIP Call, 63 FR 57371 (October 27, 1998); CAIR, 70 FR 25172 (May 12, 2005); and Transport Rule or

Cross-State Air Pollution Rule, 76 FR 48208 (August 8, 2011) 6 See http://www.epa.gov/airtrends/values.html 7 Air quality designations are not relevant to the methodology for identifying these “receptors”. See TSD for the

EPA’s Proposed Action on the State of Oregon’s 2010 Interstate Transport SIP for the 2006 24-hour Fine

Particulate (PM2.5) National Ambient Air Quality Standard, Docket ID no EPA-R10-OAR-2011-0446-0005

9
Table 2 presents a list of monitoring sites in neighboring states that are currently designated

nonattainment areas or classified as nonattainment receptors according to the criteria described

before. The selection criteria resulted in no maintenance receptors for the neighboring states. It

is worth mentioning that the design values published do not include exceptional events that have

been flagged by States, Tribes, and local agencies, and concurred by the associated EPA

Regional office:

Table 2 Design values for nonattainment receptors for the 2006 24-hour NAAQS

State County Site ID Site

name

Distance

to WA

(miles)

2009-

2011

(μg/m3)

2010-

2012

(μg/m3)

2011-

2013

(μg/m3)

Receptor

Type

ID

Ada 160010010

St.

Luke’s

Meridian

170a 19 27 53 Nonattainment

(not designated)

Lemhi 160590004 Salmon 160a 38 75 38 Nonattainment

(not designated)

Shoshone 160790017 Pinehurst 40b 38 38 40 Nonattainment

(not designated)

Franklin 160410001 Franklin 380a 50 47 42 Nonattainment

(designated)

OR

Crook 410130100 Prineville 110c 31 31 39 Nonattainment

(not designated)

Klamath 410350004 Klamath

Falls 245c 39 35 40 Nonattainment

(designated)

Jackson 410290133 Medford 245c 28 26 42 Nonattainment

(not designated)

Lake 410370001 Lakeview 250c 36 34 56 Nonattainment

(not designated)

Lane 410392013 Oakridge 145c 39 38 40 Nonattainment

(designated)

(a) Measured from OR-ID-WA border junction

(b) Straight line from eastern border

(c) Measured from Columbia River Gorge

10
Factors considered in the Transport Analysis

In order to determine whether the CAA section 110(a)(2)(D)(i)(I) requirement is satisfied, a state

needs to evaluate if its emissions contribute significantly to nonattainment or interfere with

maintenance in downwind areas.

To evaluate the potential for significant contribution to nonattainment in other states, Ecology

evaluated the potential transport to the neighboring states with the nearest identified

nonattainment receptors. The states bordering Washington with nonattainment receptors are

Oregon and Idaho. No maintenance receptors were identified in neighboring states.

Ecology reviewed ambient data from IMPROVE sites located in relatively remote ambient areas

as representative of the regional background PM2.5 levels. Table 3 lists the IMPROVE site

selected for the study:

Table 3 IMPROVE sites

Site Name State Latitude Longitude Elevation (m) Dates of operation

Cabinet Mountains MT 47.954771 -115.671925 1441 2000-present

Columbia River Gorge WA 45.664223 -121.001945 179 1993-present

Hells Canyon OR 45.079864 -116.844808 655 2000-present

Starkey OR 45.224748 -118.513962 1259 2000-present

Mount Hood OR 45.288616 -121.784861 1531 2000-present

Three Sisters Wilderness OR 44.19982 -122.044547 885 1993-present

Crater Lake National Park OR 42.91 -122.139722 0 1990-present

11
Cabinet Mountains were selected as the nearest site to Pinehurst, ID. The Columbia River Gorge

site, as well as, Mount Hood, was selected to represent the Oregon-Washington border. Hells

Canyon and Starkey were chosen because they are the closest to the Cache Valley. The Three

Sisters Wilderness site was selected because it is the nearest IMPROVE site to the Oakridge

area, and the Crater Lake National Park site is the nearest to the Klamath falls area. Figure 5

presents a map with the location of the nonattainment receptors, nonattainment designated areas

and the nearest IMPROVE monitoring sites to each identified receptor:

Figure 5 Map of receptors and IMPROVE sites used in this analysis.

Red circles indicate designated nonattainment areas (NAA), yellow circles indicate

non-designated NAA and stars represent IMPROVE sites.

12
Transport Assessment for Nonattainment

Receptors

Based on the methodology for selecting nonattainment receptors described earlier, Ecology has

identified nonattainment receptors in both Idaho and Oregon. Ecology evaluated PM2.5

monitoring data, from selected IMPROVE sites, to understand the regional background levels

near the nonattainment receptors, as well as, other IMPROVE sites along the WashingtonOregon border and those between the southern border of Washington and Idaho. Ecology also

reviewed PM2.5 data from each of the nonattainment receptors, to understand when high levels of

PM2.5 are observed, and how they relate to the background levels observed at the IMPROVE

sites.

Idaho

The general finding for the receptors in Idaho is that elevated levels of PM2.5 are observed during

the winter season, particularly during the month of January (see Appendix B). Air quality data

from IMPROVE sites shows generally low levels of PM2.5 during the periods with high levels of

fine particulate matter (see Appendix A). Both findings, as well as technical information from

the State of Idaho indicating that local emissions during winter stagnation events are the main

contributor to high levels of PM2.5, lead us to believe that Washington sources do not contribute

significantly to nonattainment of the 2006 24-hour PM2.5 NAAQS at these receptor locations. A

more detailed analysis for each receptor is presented below:

Ada County (St. Luke’s Meridian)

Ada County is situated in southwest Idaho within Treasure Valley, which is located in a shallow

basin. The Boise front, a mountain range, extends generally east-west and is approximately

6,000 feet high. This range creates a barrier to air flow on the northern edge of the valley. To

the south, the Owyhee Mountain range constitutes a further barrier to air flow. Temperature

inversions are common in the winter season, particularly in late December and early January.

These stagnation events have been cited previously by the State of Idaho as factors affecting the

buildup of pollutants in the area8

. Northern Ada County is currently a maintenance area for CO

and PM10 and an area of concern for PM2.5

9

. The design value for the period 2011-2013 is the

first one violating the PM2.5 24-hour NAAQS (see Table 2), and a closer look at local ambient

data at the St. Luke’s monitor indicates that concentrations contributing to the high design value

occurred during the late fall and winter in the 2012-2013 and 2013-2014 seasons. St. Luke’s

monitor represents the CBSA of Boise-Nampa.

IMPROVE data from the Hells Canyon and Starkey stations show values within the average

(<10 μg/m3 for last quarter) for the periods when St. Luke’s violates the 24-hour PM2.5 NAAQS,

with the exception of a period in late September of 2012, where both IMPROVE sites show a

high amount of PM2.5 (>45 μg/m3), composed mainly of organic carbon. The particular date is

September 21, which coincides with one of St. Luke’s violation days (66 μg/m3).

8 See Northern Ada County Carbon Monoxide maintenance Plan and Redesignation Request 9 https://www.deq.idaho.gov/media/662796-nonattainment_map.pdf

13
Figure 6 Sequence of MODIS satellite images on September 20 (left) and 21 (right), 2012. Red dot

indicates the approximate location of St. Luke’s Meridian monitor.10

Further research indicates that the most likely reason for this increase in PM2.5 is due to the

plume from the Wenatchee Complex wildfire (WA), started September 9, 2012 and contained on

October 30, 201211. Figure 6 shows a satellite composite image capturing the fire plume

traveling southwards on September 20 (left), and the remaining smoke in the area of the St.

Luke’s monitor on September 21 (right). This fire was part of an exceptionally large amount of

wildfires that affected the region (Washington, Oregon, western Montana and Idaho) during the

2012 wildfire season.

The St. Luke’s monitor also showed two other violations in August (8/13 and 8/23) of the same

year. However, MODIS images show smoke plumes traveling from Oregon and/or California

during those days (Figure 7).

Figure 7 MODIS satellite images for August 13 (left) and August 23 (right), 2012.

Red dot indicates the approximate location of St. Luke’s Meridian monitor.12

10 Downloaded from MODIS Today http://ge.ssec.wisc.edu/modis-today/index.php 11 See 2012 Annual Report of Wildland Fire, National Interagency Coordination Center (NICC) 12 Downloaded from MODIS Today http://ge.ssec.wisc.edu/modis-today/index.php

14
Ecology believes it is reasonable to assume that controllable Washington sources do not

contribute significantly to nonattainment of the 2006 24-hour PM2.5 NAAQS in St. Luke’s

station.

Lemhi County (Salmon)

This area is currently listed by the Idaho Department of Environmental Quality as an area of

concern for PM2.5

13. However, the highest violations in this monitor were also associated with

the 2012 wildfire season, particularly the Halstead fire that burned nearly 20,000 acres in the

Salmon-Challis National Forest in August 2012. In fact, Idaho’s Department of Environmental

Quality (IDEQ) has submitted a request to EPA to exclude these exceptional events affecting the

air quality in Salmon.

Despite these exceptional events, the design values for the first and last periods were still

violating the PM2.5 24-hour NAAQS. IDEQ recognizes that wood burning stoves used for home

heating, in combination with strong winter inversions, are a cause of concern for air quality in

the Salmon area.

The factors described above, together with the large distance between this receptor and

Washington, lead us to assume that Washington sources do not contribute significantly to

nonattainment of the 2006 24-hour PM2.5 NAAQS in Salmon, ID.

Franklin County (Franklin)

Portions of the Franklin County, Idaho and Cache County, Utah are designated as part of the

Cache Valley 2006 24-hour PM2.5 two-state nonattainment area. EPA’s technical analysis

determined the PM2.5 problem is dominated by ammonium nitrate aerosol. Transport of PM2.5

precursors from near rural regions is small and the majority of the observed PM2.5 is formed insitu (and trapped due to strong inversions) from local emission sources.

Ecology believes it is safe to assume that Washington sources do not contribute significantly to

nonattainment of the 2006 24-hour PM2.5 NAAQS in the Cache Valley.

Shoshone County (Pinehurst)

Pinehurst is located in a small, enclosed, bowl-shaped area of the Coeur d’Alene River, known as

Silver Valley. Stagnation events during winter season are one of the main reasons behind the

violations to the 2006 24-hour PM2.5 NAAQS. It must be noted that Pinehurst is currently under

EPA’s recommendation for nonattainment area for the 2012 annual PM2.5 NAAQS14.

13 https://www.deq.idaho.gov/media/662796-nonattainment_map.pdf 14 See http://www.epa.gov/airquality/particlepollution/designations/2012standards/eparesp/10_ID_120resp.pdf

15
Technical analysis performed by the State of Idaho15 determined, through dispersion modeling,

that Pinehurst is largely cut off from the Silver Valley airshed, implying that there is little to no

exchange of air between Pinehurst and other towns in the main Silver Valley. The greatest

contributing emissions source to PM2.5 concentrations above the 24-hour standard that occurs

consistently is residential wood heating. Slash burning was also established as a large emissions

source that can contribute to a violation of the 24-hour PM2.5 standard. However, the location

and time of occurrence vary from year to year.

EPA’s technical analysis for Shoshone County16 established that the days with the highest fine

particle concentrations occur predominantly in winter, with carbonaceous PM2.5 and nitrate being

the largest components of the fine particle mass. These components are consistent with

emissions from various combustions sources, such as woodstoves, fireplaces with various inserts,

wood pellet stoves, open and slash burning, and vehicle tailpipe emissions. The facts described

lead EPA to believe that combustion related sources present in the local area may have a large

contribution to the PM2.5 values in the violating monitor. Analysis of wind direction data off

Spokane was not considered here as EPA’s technical analysis (mentioned before) determined

that, due to the complex terrain and meteorology of Pinehurst, data from locations as far as

Spokane is not representative of local conditions, and thus would be misleading.

After reviewing all the information described above, Ecology believes it is reasonable to assume

that Washington sources do not contribute significantly to nonattainment of the 2006 24-hour

PM2.5 NAAQS in Pinehurst, ID.

Oregon

The general conclusion for the receptors in Oregon is similar to the findings described for Idaho.

The majority of the violations to the 24-hour PM2.5 NAAQS occur in the winter season,

particularly in the month of January. Ecology reviewed ambient data from the receptors and

regional background data from IMPROVE sites. In addition, Ecology reviewed technical

information from the State of Oregon (Oregon Department of Environmental Quality, ODEQ)

and EPA determining that local sources in conjunction with strong inversions are the main

contributors to violations of the 24-hour PM2.5 standard, at least in the already designated NAA.

The information reviewed leads us to believe that Washington sources do not contribute

significantly to nonattainment of the 2006 24-hour PM2.5 NAAQS in any of the receptors located

in Oregon. A more detailed analysis for each receptor is presented below:

Crook County (Prineville)

Crook County is located in the center of Oregon. The Cascade Mountain range runs through the

western part of the region, while high desert comprises the eastern part. The Ochoco Mountains

are located in the northeastern area. Prineville is located in the rain shadow of the Cascades and

has a mild and relatively dry climate.

15 See Idaho Area, Designation Recommendations for the 2006 PM2.5 NAAQS, Docket ID no. EPA-R10-OAR-2008-

0336-0012 16 See EPA Technical Analysis for Shoshone County, Docket ID no. EPA-HQ-OAR-2007-0562-0369, Attachment 2

16
Aerosol Composition at CORI1 2009-2013

(monthly averages)

7

6

5

salt

4 soil

3 EC

2 OMC

amm. nitrate

1 amm. sulfate

0

Within Central Oregon, Crook County is the third highest wood burning county, with its

neighboring county Deschutes being the first17. There is no PM2.5 speciation data for the

Prineville monitoring station, but daily mean PM2.5 concentration time series between 2009 and

2013 (see Appendix B) show that the highest values are centered on December-January,

indicating a likely association with wood combustion from residential heating activities. It is

interesting to note that the 2011-2013 design value is the first time that this monitor has violated

the 24-hour PM2.5 NAAQS.

Background regional levels at the Three Sisters Wilderness IMPROVE station are generally low

during the winter months, with levels <10 μg/m3

. Background levels at the IMPROVE sites

along the Oregon-Washington border show overall very low levels (<5 μg/m3 at Mount Hood)

during winter months. The Columbia River Gorge station presents a higher background

throughout the year, with a less clear seasonality. However, looking at the composition data, a

clear increase in ammonium nitrate is observed for the winter season (see Figure 8):

Figure 8 Composition of PM2.5 at Columbia River Gorge station

The winter increase in ammonium nitrate is likely due to mixture of emissions from local

agricultural and industrial activities. The range of maximum ammonium nitrate concentrations

observed at CORI1is less than 3 μg/m3 for the months of December and January. Prineville is

approximately 95 miles south from CORI1, thus it is unlikely that contributions from these local

activities will reach Prineville during the times that exceedances occur. This is further confirmed

by the fact that the majority of the high concentrations observed at the Prineville monitor occur

at low wind speeds, likely associated to stagnation events (see Figure 8).

17 See Oregon 2005 Residential Wood Combustion Emission Inventory, ODEQ Mass (ug/m3)

17
Figure 9 Correlation between PM2.5 and wind speed at Prineville, OR (hourly data)

Because of the factors reviewed before, Ecology believes it is reasonable to assume that

Washington sources do not contribute significantly to nonattainment of the 2006 24-hour PM2.5

NAAQS in Prineville, OR.

Klamath County (Klamath Falls)

Klamath Falls is located in the Klamath basin surrounded by mountains on three directions and

the Upper Klamath Lake on the other. These features are conducive for air stagnation

episodes19. Strong wintertime temperature inversions are common. The core of high

concentrations is observed during the winter months (see Appendix B). The area has been

declared nonattainment for the 24-hour PM2.5 NAAQS. A combination of strong inversions and

cold temperatures increasing hours with residential heating activities has been cited as the cause

behind the current designation. In addition, EPA’s analysis shows that Klamath Falls is

topographically isolated from other areas further confirming that local sources are the main cause

for pollution events20.

For the reasons mentioned, as well as due to the considerable distance to this receptor, Ecology

believes it is reasonable to assume that Washington sources do not contribute significantly to

nonattainment of the 2006 24-hour PM2.5 NAAQS in Klamath Falls, OR.

18 Data from ODEQ, LASAR Database, http://deq12.deq.state.or.us/lasar2/

19 See Klamath Falls PM2.5 Attainment Plan Appendix 9 Topography and Winter Meteorology and 2008 as a Base

Year, ODEQ, submitted to EPA, December 2013 20 See EPA Technical Analysis for Klamath Falls Oregon, Docket ID No.EPA-HQ-OAR-2007-0562-0370

160

140

120

100

80

60

40

20

0

0 2 4 6

Wind Speed (mph)

8 10 12

PM2.5 (ug/m3)

18

18
Jackson County (Medford)

Medford lies in a topographic bowl in the Rogue Valley in southern Oregon, sharing its airshed

with the city of Ashland. Mountains surround the valley on all sides; to the east the Cascades,

range up to 9,500 feet; to the south, the Siskiyous, range up to 7,600 feet; and to the west and the

north, the Coast Range and the Umpqua Divide, range up to 5,500 feet. Winds exceeding 10

mph during winter nearly always come from the southwest21 while more common, light valley

winds are mostly northerly or northwesterly. Inversions are a common occurrence in winter,

causing episodes of pollution and the stagnation conditions that can last several days. Jackson

County is at the top of the list in estimated tons of wood fuel burned within Southwest Oregon22

suggesting that wood burning for residential heating activities during stagnation periods is the

likely reason for the violations to the 24-hour PM2.5 NAAQS. Medford is currently a

maintenance area for CO and PM10. The PM10 SIP maintenance plan highlighted control

measures particularly focused on wood smoke from residential heating, open burning, industrial

emissions, and mobile sources (on-road and non-road).

The design value for the period 2011-2013 is the highest value reported for this location. Air

quality data available for Medford shows an increase in concentrations during the winter season

(Appendix B). Three other events in August and September 2013 seem to be related to the

Douglas Complex wildfire that started July 26th and was not contained until October 23rd. The

impact of the fires can also be observed at the Crater Lake National Park IMPROVE station,

which otherwise shows extremely low values (<5 μg/m3

) during the period of increase in PM2.5

at Medford.

Considering the topographic and meteorological features of the Medford-Ashland area, plus the

considerable distance from Washington border, Ecology believes that Washington sources do not

contribute significantly to nonattainment of the 2006 24-hour PM2.5 NAAQS in Medford, OR.

Lake County (Lakeview)

Lakeview is located about 96 miles east of Klamath Falls, at an elevation of 4,800 feet, in Goose

Lake Valley, at the foot of the Warner Mountains. Strong winter inversions can occur and

reoccur for many days in a row. The Lakeview Urban Growth Boundary is currently a

maintenance area for PM10.

Lakeview has not been formally designated as a nonattainment area. But, since the 24-hour

PM2.5 NAAQS was revised in 2006, Lakeview has, more than once, come close to or exceeded

the standard. In consequence, Lakeview and Lake County have voluntarily signed to participate

in the EPA’s PM Advance Program to reduce PM2.5, and recently submitted the Advance Action

Plan to EPA.

21 See State Implementation Plan for PM10 Medford-Ashland Air Quality Maintenance Area, ODEQ 22 See Oregon 2005 Residential Wood Combustion Emission Inventory, ODEQ

19
Considering EPA studies23 show a significant contribution of wood smoke to the annual average

of PM2.5, and that an emissions inventory performed by ODEQ shows the majority of the direct

PM2.5 emissions coming from residential wood combustion24, Ecology assumes that local

sources, in combination with meteorology are the main reason behind the nonattainment

conditions.

In conclusion, Ecology believes it is safe to say that Washington sources do not contribute

significantly to nonattainment of the 2006 24-hour PM2.5 NAAQS in Lakeview, OR.

Lane County (Oakridge)

Oakridge is located in a valley oriented east-west in the foothills of the Cascade Range,

surrounded by the Willamette National Forest. The Oakridge Urban Growth Area is currently a

maintenance area for PM10 and nonattainment for PM2.5.

Oakridge is a rural mountainous community. Analysis performed by EPA25, related to the

recommendation for NAA designation, shows that the majority of the exceedances occur during

extended night time inversions and low wind speed. PM2.5 levels generally increase in late

afternoon, reach a peak at midnight, and then begin to decrease. This profile is characteristic of

residential wood combustion. In addition, the analysis also determined that there is no

correlation between concentrations in Oakridge and concentrations in surrounding urban areas,

thus demonstrating that there is no transport from nearby counties.

For the reasons stated above, Ecology believes that it is highly unlikely that transport from

Washington sources contributes significantly to nonattainment of the 2006 24-hour PM2.5

NAAQS in Oakridge, OR.

23 See Kotchenruther R.A., A regional assessment of marine vessel PM2.5 impacts in the US Pacific Northwest

using a receptor-based source apportionment method, Atmospheric Environment 68, 2013, pp103-111 24 See Lakeview Area - Particulate Matter (PM2.5) Advance Action Plan, by Town of Lakeview, Lake County and

ODEQ, submitted to EPA, September 2014 25 See EPA Technical Analysis for Oakridge Oregon, Docket ID No.EPA-HQ-OAR-2007-0562-0370

20
Appendices

Appendix A. IMPROVE PM2.5 data for the period 2009-2013

1. Northern Idaho – closest station is Cabinet Mountains (CABI1)

2. Oregon-Washington border – closest stations are Columbia River Gorge (CORI1) and Mount Hood (MOHO1)

3. Eastern Oregon – closest stations to Idaho border are Hells Canyon (HECA1) and Starkey (STAR1)

4. Southern Oregon – closest stations to designated NAA are Three Sisters Wilderness (THSI1) and Crater Lake National park

(CRAL1)

Data can be downloaded from http://views.cira.colostate.edu/fed/DataWizard/

1
Figure A- 1 Northern Idaho, Cabinet Mountains station

Figure A- 2 Washington-Oregon border, Columbia River Gorge station

2
Figure A- 3 Washington-Oregon border, Mount Hood station

Figure A- 4 Eastern Oregon, Hells Canyon station

3
Figure A- 5 Eastern Oregon, Starkey station

Figure A- 6 Southern Oregon, Crater Lake National Park station

4
Figure A- 7 Southern Oregon, Three Sisters Wilderness station

5

Appendix B. PM2.5 data for the period 2009-2013

Data can be downloaded from AirData website http://www.epa.gov/airdata/

Figure B- 1 PM2.5 data for Pinehurst site, Shoshone County, ID

1
Figure B- 2 PM2.5 data for St. Luke’s Meridian site, Ada County, ID

2
Figure B- 3 PM2.5 data for Salmon site, Lemhi County, ID

3
Figure B- 4 PM2.5 data for Prineville site, Crook county, OR

4
Figure B- 5 PM2.5 data for Klamath Falls site, Klamath county, OR

5
Figure B- 6 PM2.5 data for Medford site, Jackson County, OR

6
Figure B- 7 PM2.5 data for Lakeview site, Lake County, OR

7
Figure B- 8 PM2.5 data for Oakridge site, Lane County, OR

8