Appendix B – Nonattainment Receptors 

1

Technical Support Document for EPA’s Proposed Action on the 

State of Nevada’s 2009 Infrastructure State Implementation Plan (Transport Portion) for the 

2006 24-hour Fine Particulate (PM2.5) National Ambient Air Quality Standard 

Appendix B – Nonattainment Receptors 

1. EPA Region 9 States – California 

1. Eastern California – Inyo County 

2. Southern California – Los Angeles, Riverside, and San Bernardino Counties 

3. Northern California – Butte, Sacramento, and Sutter Counties 

4. Central California – Fresno, Kern, Kings, Merced, San Joaquin, Stanislaus, and Tulare 

Counties 

5. California/Mexico Border – San Diego County 

2. EPA Region 8 States – Montana and Utah 

1. Montana – Silver Bow County (Butte) 

2. Utah – Utah County (Provo-Orem) 

3. Utah – Box Elder, Davis, Salt Lake, and Weber Counties (Greater Salt Lake Area) 

3. EPA Region 10 States – Idaho, Oregon, and Washington 

1. Idaho/Utah – Franklin County/Cache County 

2. Idaho – Shoshone County (Pinehurst) 

3. Oregon – Klamath County (Klamath Falls) 

4. Oregon – Lake County (Lakeview) 

5. Oregon – Lane County (Oakridge) 

6. Washington – Pierce County (Tacoma) 

7. Washington – Yakima County (Yakima) 

Note: See Appendix E for further technical data for Greater Salt Lake Area, Utah and Butte, Montana. 

 
Appendix B – Nonattainment Receptors 

2

1.1. Eastern California – Inyo County 

County Site Name Description 

Inyo Keeler This area has not been designated nonattainment. 

This site is affected primarily is by local crustal sources. 

Massive erosion from Owens dry lake; in Owens Valley. 

Elevated levels of PM2.5 in Inyo County are measured at a single monitor, the Keeler monitor, which is 

located adjacent to the Owens Lake Bed. (See Figures 1.1.A and 1.1.B, below). The Owens Lake Bed is 

surrounded by steep terrain. (See Figure 1.1.C, below). EPA believes that because of the proximity of 

the monitor to a large local source of particulate matter, and the steep nearby terrain, it is reasonable to 

conclude that Nevada does not contribute to nonattainment of the 24-hour PM2.5 standard at this 

monitor. 

The Owens Valley Planning Area is located in Inyo County in eastern-central California. It is situated at 

the south end of the deep, long, narrow Owens Valley with the Sierra Nevada to the west (maximum 

elevation 14,495 feet), the Inyo Mountains to the east (maximum elevation 14,246 feet), and the Coso 

Range to the south (maximum elevation 8,160 feet) (Figure 1.1.C). The predominantly dry, alkaline 

Owens Lake bed is approximately eight miles south of the community of Lone Pine on U.S. Highway 

395, 60 miles north of the city of Ridgecrest, and 35 miles west of Death Valley. The bed of Owens 

Lake is defined as the area below 3,600 feet above mean sea level (all elevations will be given in feet 

above mean sea level). The lake bed extends about seventeen miles north and south and ten miles east 

and west and covers an area of approximately 110 square miles (70,000 acres). 

Table 1: PM2.5 Levels at the Keeler Monitor 

Year Date PM2.5 Level (μg/m3) 

2006 December 28 193 

2007 March 28 

November 11 

43 

57 

2008 March 1 

April 15 

April 30 

May 21 

58 

48 

43 

44 

2009 March 26 

March 29 

36 

69 

2010 June 10 44 

Owens Lake is the largest single source of PM-10 in the United States.

1

 Water was first diverted from 

the Owens River to the City of Los Angeles in 1913, and by 1926 Owens Lake was dry. Today, the 

 

1

http://www.gbuapcd.org/owenslake.htm
Appendix B – Nonattainment Receptors 

3

Owens lakebed produces enormous amounts of windblown dust in exceedance of federal air pollution 

standards for particulate matter. 

Monitoring and research conducted for more than 20 years, as well as three previous State 

Implementation Plans (SIPs), has determined that wind-blown dust from the dry bed of Owens Lake is 

the dominant cause of NAAQS violations for PM10 in the nonattainment area. 

2

Figure 1.1.A: Keeler Dunes 3

 

2

Final 2008 Owens Valley PM10 Planning Area Demonstration of Attainment State Implementation Plan, January 28, 2008. 

http://www.gbuapcd.org/ovpm10sip.htm

3

http://www.gbuapcd.org/owenslake/dustID/20120516CurrentSites.
Appendix B – Nonattainment Receptors 

4

Figure 1.1.B: Owens Lake Dust ID Network Map 
Appendix B – Nonattainment Receptors 

5

Figure 1.1.C: Model domain and one-km mesh size terrain (m) 4

 

4

Final 2008 Owens Valley PM10 Planning Area Demonstration of Attainment State Implementation Plan, January 28, 2008, 

Chapter 6, Figure 6.3. http://www.gbuapcd.org/ovpm10sip.htm. 
Appendix B – Nonattainment Receptors 

6

1.2. Southern California – Los Angeles, Riverside, and San Bernardino Counties 

County Site Name Description 

Los Angeles Azusa Current monitored values are below 35μg/m3. There is a strong 

downward trend. 

Riverside Mira LomaVan Buren Current monitored values slightly above 35μg/m3. There is a strong 

downward trend. 

San 

Bernardino 

Fontana Current monitored values slightly above 35μg/m3. There is a strong 

downward trend. 

The high PM2.5 concentrations in the South Coast Air Basin are mainly due to the secondary formation 

of smaller particulates resulting from mobile, stationary and area source emissions of precursor gases 

(i.e., NOx, SOx, NH4, and VOC) that are converted to PM in the atmosphere. 

Speciated PM2.5 data at the Central Los Angeles Site (CELA) and the Rubidoux site (RIVR) indicate 

that organic carbon, ammonium nitrate, and ammonium sulfate constitute the major components at each 

site (shown in Figures 1.2.A and 1.2.B, below). 24-hour PM2.5 design value trends show strong 

downward trend at all sites in the South Coast Basin (shown in Figure 1.2.C, below).5

PM2.5 is essentially a combustion generated pollutant due to the volume of traffic flow and numbers of 

sources (both point and area) located in the region. It is important to note that the areas with the highest 

concentrations are directly downwind of an area with major ammonia sources associated with dairies 

and poultry farming.6

The South Coast Air Quality DRAFT 2012 Air Quality Management Plan7air quality projections show 

that the emission control strategy outlined in the plan will result in air quality improvement at each of 

the nonattainment receptors, and that each of these sites will attain the standard in 2014 or sooner (see 

Figure 1.2.D: Maximum 24-Hour Average PM2.5 Design Concentrations: 2008 Baseline, 2014 and 

2014 Controlled). 

The spatial distribution of PM2.5 in the South Coast Basin supports the fact that it is largely of local 

origin. The air quality trends and projections indicate that the emission strategy is effective in reducing 

PM2.5. Therefore, it is reasonable to conclude that transport from Nevada does not contribute 

substantially to violations of the 2006 PM2.5 standard at these receptors. 

 

5

Joe Cassmassi, Scientific, Technical & Modeling Peer Review (STMPR) Advisory Group Meeting, September 22, 2011. 

6

Final 2007 Air Quality Management Plan (AQMP), Appendix V – Modeling and Attainment Demonstrations June, V-2-10. 

7

http://www.aqmd.gov/aqmp/2012aqmp/draft/Chapters/Ch5.pdf
Appendix B – Nonattainment Receptors 

7

Figure 1.2.A: Speciated data for Central Los Angeles8

 

8

STMPR Item # 5 - 2008 PM2.5 Air Quality Characterization, January 19, 2012. Bong-Mann Kim. 
Appendix B – Nonattainment Receptors 

8

Figure 1.2.B: Speciated PM2.5 data for the Rubidoux site in Riverside County 9

 

9

STMPR Item # 5 - 2008 PM2.5 Air Quality Characterization, January 19, 2012. Bong-Mann Kim. 
Appendix B – Nonattainment Receptors 

9

Figure 1.2.C: 24-hour PM2.5 Design Value Trends 

 
Appendix B – Nonattainment Receptors 

10

Figure 1.2.D: Maximum 24-Hour Average PM2.5 Design Concentrations: 

2008 Baseline, 2014 and 2014 Controlled10

 

10 http://www.aqmd.gov/aqmp/2012aqmp/draft/Chapters/Ch5.pdf
Appendix B – Nonattainment Receptors 

11

1.3. Northern California – Butte, Sacramento, and Sutter Counties 

County Site Name Description 

Butte Chico This receptor is in the Chico nonattainment area. 

The monitored exceedances likely reflect localized sources occurring 

during wintertime temperature inversions with low winds that persist 

for several days in an area that trap emissions together with complex 

topography. The speciation data from high concentration days 

indicates that as much as 75% of the concentrations are due to organic 

carbon, which also indicates that residential wood burning emissions 

are the dominant source. Also, about 70% of the emissions are 

estimated to be from area sources, of which residential wood burning is 

the dominant source, contributing 2.65 of the 6.4 tons per day (ARB 

Almanac website (2006) 

http://www.arb.ca.gov/ei/maps/statemap/cntymap.htm) 

Sacramento SacramentoDel Paso 

Manor 

This receptor is in the Sacramento Metro nonattainment area. 

The monitored exceedances likely reflect localized sources occurring 

during wintertime temperature inversions with low winds that persist 

for several days. The speciation data on days during cold seasons in 

2004-2006 with the highest 5 percentile of PM2.5 concentrations show 

that the mass is 47-60% total carbon mass (TCM), which indicates 

residential wood burning as a significantly contributing source 

(http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_F_li

mited_2004-06_speciation_data_report.pdf). 

The largest single source of Sacramento's wintertime PM2.5 emissions 

is wood and other solid fuel burning in fireplaces, wood inserts, wood 

stoves and pellet stoves. 

There is a strong downward trend in this area in recent years 

(http://www.epa.gov/region9/air/trends/pm25.html). 

Sutter Yuba City Yuba City-Marysville 

The monitored exceedances likely reflect localized sources occurring 

during wintertime temperature inversions with low winds that persist 

for several days. 

There is a strong downward trend and preliminary 2009-2011 data 

indicates the area may be attaining the standard. 

(http://www.epa.gov/region9/air/trends/pm25.html). 
Appendix B – Nonattainment Receptors 

12

The Northern Sacramento Valley Air Basin is bounded on north and west by the Coastal Mountain 

Range and on the east by the southern portion of the Cascade Mountain Range and the northern portion 

of the Sierra Nevada Mountains. These mountain ranges reach heights in excess of 6,000 feet with peaks 

rising much higher. This provides a substantial physical barrier to locally created pollution. 

For the areas under consideration, high PM2.5 concentrations mostly occur during stagnant conditions 

during winter, with radiation inversions. The cooling of the ground, as heat is radiated away, creates an 

inversion, since air near the ground is cooler than that above. This inhibits mixing and confines 

pollutants to a relatively shallow layer near the ground. A typical value for maximum mixing height 

during high PM2.5 conditions is 300 meters (984 feet) AGL (above ground level). EPA recognizes that 

an inversion height is not a rigid boundary extending through a fixed elevation. In reality the inversion 

would be partly terrain-following, and the degree of stagnation would be subject to additional influences 

at the foothill edges, such as strong diurnal slope flows. In any case, mixing heights vary by site and 

date, so any single height can provide only a scale for comparison, not a definitive value. Nevertheless, 

the inversion height provides an indicator of the area over which inversions may be enhancing pollution 

concentrations, and of the extent of the area that may be contributing to NAAQS violations. 

Because these areas in Northern California have topographical features higher than the typical daytime 

height of the inversion layer, EPA considered the inversion height to estimate the size of the area likely 

to have similar pollution conditions and to contribute to NAAQS violations. For example, the eastern 

portion of Butte County extends into the foothills of the Sierra Nevada Mountains. For Chico, the 300 

meters AGL (984 feet) inversion layer thickness translates to an elevation contour of 375 m (1221 feet) 

MSL (above Mean Sea Level). Much of eastern portion Butte County is above this elevation, as shown 

in Figure 1.3.B below. 

In summary, topography is an important in factor these areas, given that the inversion layer, which can 

lead to winter PM2.5 exceedances in the Sacramento Valley, is blocked by the Sierra foothills. 

The steep terrain and speciated PM2.5 data at these Northern California receptors supports the fact that 

the PM2.5 is largely of local origin. Therefore, it is reasonable to conclude that transport from Nevada 

does not contribute substantially to violations of the 2006 PM2.5 standard at these receptors. 
Appendix B – Nonattainment Receptors 

13

Figure 1.3.A: Average Composition on 14 Exceedance Days - Chico 

Average Composition on

14 Exceedance Days- Chico

AmmNitrate

16%

AmmSulfate

2%

OC

75%

Other

2%

Geological

1%

Elements

2%

EC

2%

PM2.5 Mass= 52.2 ug/ m3

Sum of Species=51.4 ug/ m3
Appendix B – Nonattainment Receptors 

14

Figure 1.3.B: Map of Butte County PM2.5 Nonattainment Area 
Appendix B – Nonattainment Receptors 

15

1.4. Central California – Fresno, Kern, Kings, Merced, San Joaquin, Stanislaus, and Tulare 

Counties 

County Site Name 

Fresno Fresno-1st Street 

Kern Bakersfield-Planz Road 

Kings Corcoran 

Merced Merced-M Street 

San Joaquin Stockton-Hazelton 

Stanislaus Turlock 

Tulare Visalia 

PM2.5 levels in the San Joaquin Valley are generally highest in the months of January, February, 

November and December (see Figure 1.4.A, below). PM2.5 builds up in episodes of several days or 

weeks. These episodes generally occur during periods with stagnation, cool temperatures, high 

humidity, and low mixing depths.

11 The peak day composition of PM2.5 at Bakersfield is primarily 

ammonia nitrate (67%) and organic carbon (16%). 

The primary sources of PM2.5 in the region are diesel engines (nitrate), gasoline engines (nitrate), and 

agricultural activities (ammonium) which contribute regionally. Wood smoke (organic carbon) and 

diesel engines (elemental carbon) contribute to the elevated levels of PM2.5 in urban areas. 

Because PM2.5 builds up in episodes of several days or weeks, during periods with stagnation, and low 

mixing depths, it is reasonable to conclude that long range transport does not contribute to elevated 

levels PM2.5 in the San Joaquin Valley. EPA believes it is reasonable to conclude that Nevada does not 

contribute to nonattainment of the 24-hour PM2.5 standard at these receptors. 

 

11

 Nature of PM2.5 in the San Joaquin Valley, Karen Magliano, California Air Resources Board, Technical Symposium 

April 27, 2012. 
Appendix B – Nonattainment Receptors 

16

Figure 1.4.A: Monthly Average PM2.5 Concentration in Bakersfield California 
Appendix B – Nonattainment Receptors 

17

Figure 1.4.B: 2008-2010 Peak Day Composition in Bakersfield 

 
Appendix B – Nonattainment Receptors 

18

1.5. California/Mexico Border – San Diego County 

San Diego La Posta 

Band Of 

Mission 

Indians 

This area has not been designated nonattainment. 

This receptor‘s status is based on a single high value of 114 μg/m3, measured on June 1, 2010. Measured 

values of PM2.5 at the La Posta site are very low for other days. On June 1, 2010, the La Posta monitor 

recorded the highest measured 24-hour PM2.5 value in all of California (99% of values for the rest of 

the State were below 20 μg/m3). The monitoring site is located approximately 200 miles from the 

border of Nevada. Given the very low levels of PM2.5 measured at all other sites on the only day above 

35μg/m3, it is reasonable to conclude that there is not a significant contribution to the elevated PM2.5 

levels from emissions of PM2.5 or PM2.5 precursors from the state of Nevada to this receptor. 

2. EPA Region 8 States – Montana and Utah12

2.1. Montana – Silver Bow County (Butte) 

This area has not been designated nonattainment. 

The exceedances in Butte only occurred in January and December of both 2009 and 2010. The Butte 

area is topographically prone to temperature inversions, as it is in a montane valley. The emissions 

causing exceedances are primarily from wood smoke. 

2.2. Utah – Utah County (Provo-Orem) 

A large portion of Utah County is designated as the Provo 2006 PM2.5 nonattainment area (NAA). 

The Provo NAA is situated in the Utah Valley. Like the other low-lying valleys just west of the Wasatch 

Front, the topography of the Utah Valley makes it prone to temperature inversions. During inversions, 

the Provo NAA features stagnant air masses and calm to light winds. As the airshed is essentially 

capped, PM2.5 is formed in-situ (and trapped) via fresh locally derived emission sources and secondary 

chemistry. Transport of air masses between the Salt Lake City and Provo NAAs can occur during 

inversions, as there is a 4.75-mile gap in the mountains separating these airsheds which is below the 

approximate average inversion height for these areas. 

Speciation data from exceedance days from 2004-2006 showed the average composition of PM2.5 in 

Provo is 71% ammonium nitrate, with 21% carbon and organic compounds, 8% ammonium sulfate, and 

2% crustal. 

Several factors, including significant mobile, point and area sources contribute to primary and 

secondarily formed PM2.5 that violate the standard during stable weather events associated with strong 

inversions. 

 

12 For discussion of the Idaho/Utah – Franklin County/Cache County area, see section 3.1 of this Appendix. 
Appendix B – Nonattainment Receptors 

19

2.3. Utah – Box Elder, Davis, Salt Lake, and Weber Counties (Greater Salt Lake Area) 

(Site names: Brigham City, Ogden-Clearfield, and Salt Lake City) 

 

All of Davis and Salt Lake counties and portions of Box Elder, Tooele and Weber counties are 

designated as part of the Salt Lake City 2006 PM2.5 nonattainment area. 

The SLC NAA is situated in a valley bordered on the west by the Stansbury Mountains, Promontory 

Mountains and Great Salt Lake, and on the east by the Wasatch Front. During inversions, the NAA 

becomes a closed airshed (save for potential transport between the Salt Lake City and Provo NAAs) 

featuring stagnant air masses and light winds which typically oscillate back and forth within the airshed. 

As the airshed is essentially capped during inversions, PM2.5 is formed in-situ (and trapped) via fresh 

locally derived emission sources and secondary chemistry. 

Speciation data from exceedance days from 2004-2006 showed the average composition of PM2.5 in 

Salt Lake City is 58% ammonium nitrate, 31% carbon and organic compounds, 8% ammonium sulfate, 

and 2% crustal. 

Several factors, including significant mobile, point and area sources contribute to primary and 

secondarily formed PM2.5 that violate the standard during stable weather events associated with strong 

inversions. 

3. EPA Region 10 States – Idaho, Oregon, and Washington 

3.1. Idaho/Utah – Franklin County/Cache County 

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

2006 PM2.5, two-state, nonattainment area.

Limited chemical speciation data in the Cache Valley indicates the PM2.5 problem is dominated by 

ammonium nitrate aerosol similar to nonattainment areas along the Wasatch front in and near Salt Lake 

City. The chemical speciation monitor in Bountiful is closest to the Cache Valley and is considered 

broadly representative of conditions in the Cache Valley. 

The ridge dominated synoptic meteorology during PM2.5 cold pool episodes features weak transport 

winds and near calm surface winds. As a result, transport of PM2.5 and precursors from the rural regions 

at the domain periphery is very small. In addition, most of the observed Wasatch Front and Cache 

Valley PM2.5 is formed in-situ (and trapped) via fresh locally derived emission sources and secondary 

chemistry. 

Local heating emissions from woodstoves, emissions from agricultural activities, and mobile emissions 

contribute to primary and secondarily formed PM2.5 that violate the standard during stable weather 

events associated with extremely strong inversions. 

These emissions and the related effects are limited to the Cache Valley, as they are trapped there due to 

temperature inversions, low wind, and local topography. The rest of the county is very sparsely 
Appendix B – Nonattainment Receptors 

20

populated with no significant sources that can contribute to a violation of the PM2.5 standard at the 

Franklin monitor.

EPA Region 10 Positive Matrix Factor (PMF) receptor modeling identified 11 factors contributing to 

elevated wintertime PM2.5 at the Bountiful monitoring site including nitrate rich (56%), ammonium 

chloride (15%), wood smoke (10%), organic pyrolysis rich (6%), sulfate rich (5%) and smaller 

contributions by other identified factors (gasoline vehicles, 2 soil factors, fireworks, iron rich, and urban 

unidentified). 

3.2. Idaho – Shoshone County (Pinehurst) 

This area has not been designated nonattainment. 

State information indicates that emissions from woodstoves contribute to primary PM2.5 that violates 

the standard during stable weather events associated with strong inversions. These emissions and the 

related effects are limited to the city of Pinehurst airshed, as they are trapped there due to temperature 

inversions, low wind and local topography. 

The rest of the county is very sparsely populated with no significant sources that can contribute to a 

violation of the PM2.5 standard at the Pinehurst monitor. 

3.3. Oregon – Klamath County (Klamath Falls) 

A portion of Klamath County is designated nonattainment for the 2006 PM2.5 NAAQS. Klamath Falls 

is a relatively small urban community located in and supporting a vast rural area in south-central 

Oregon. 

State analysis includes a 2005 emission inventory that shows that wood stove emissions are the most 

significant source of emissions. Additional air quality monitoring data provide supporting evidence that 

residential wood combustion emissions are the primary cause of exceedance days. 

Data shows exceedances occur during winter months, at a time when woodstoves are contributing to 

smoke in the area. Exceedances occurred from December through January, corresponding directly with 

the winter wood heating season and indicate the exceedances are a seasonal occurrence except flagged 

wildfire events. 

Speciation data analysis indicates most of the PM2.5 comes from elemental and organic carbon, typical 

indicators of combustion activities such as wood burning. 

Meteorological data from Klamath Falls show that low wind speeds dominate during violating days, and 

the Klamath Falls area experiences frequent winter-time nocturnal inversions, when PM pollution can 

build up over time. 

Diurnal concentrations of PM2.5 are observed by hourly light scatter data that correspond closely with 

night-time use of woodstoves. 

Night-time inversions coupled with low wind speeds strongly suggest that pollution in the Klamath Falls 

area is a localized effect heavily influenced by the use of woodstoves. 
Appendix B – Nonattainment Receptors 

21

EPA Region 10 PMF receptor modeling identified the 6 factors contributing to elevated wintertime 

PM2.5 including wood smoke (65%), organic pyrolysis rich (23%) and smaller contributions by other 

identified factors (nitrate rich, soil, sulfate rich, and urban unidentified). 

3.3. Oregon – Lake County (Lakeview) 

This area has not been designated nonattainment. 

EPA Region 10 PMF receptor modeling identified 7 factors contributing to PM2.5 including wood 

smoke (67%), organic pyrolysis rich (13%), nitrate rich (7%), soil (5%) and smaller contributions by 

other identified factors (sulfate rich and urban unidentified). 

3.4. Oregon – Lane County (Oakridge) 

A portion of Lane County is designated nonattainment for the 2006 PM2.5 NAAQS. 

EPA’s technical analysis points to residential home heating using wood burning appliances as being the 

main contributors to fine particle pollution in this area.

EPA Region 10 PMF receptor modeling identified 7 factors contributing to elevated wintertime PM2.5 

including wood smoke (76%), organic pyrolysis rich (15%) and smaller contributions by other identified 

factors (gasoline vehicles, iron rich, sulfate rich, sea salt, and soil).

3.5. Washington – Pierce County (Tacoma) 

(Site name: Tacoma-South L Street) 

A portion of Pierce County (Tacoma) is designated nonattainment for the 2006 PM2.5 NAAQS.

The state analysis indicates that wood smoke associated with home heating is the largest source of 

PM2.5 in the Tacoma-Pierce County nonattainment area. 

The state data asserts that the PM2.5 problem is highly localized. Surface measurements at multiple 

sites suggest that the only design values which violate the 2006 PM2.5 NAAQS are in the core of the 

nonattainment area, within about 3 km of the South L Street monitor. Beyond about 3-5km, the design 

values drop and are well below the NAAQS. 

On-site sonic anemometer and vertical temperature profile measurements revealed that exceedances 

only occurred: in winter; at night; when there was a surface inversion; below an ambient temperature of 

about 50F; when wind speeds were less than 1.5 mph. 

Within 3km of the South L Street monitor, during the season in which the violations occur, wood smoke 

is the largest source, on-road mobile is second but appears to be significantly smaller, industrial and 

other sources make up the remainder and are minor. 

EPA Region 10 PMF receptor modeling identified 10 factors contributing to elevated wintertime PM2.5 

including wood smoke (60%), organic pyrolysis rich (10%), nitrate rich (7%), iron rich (7%), sulfate 

rich (5%) and smaller contributions from other identified factors (gasoline vehicles, sea salt, soil, aged 

sea salt, and a 2nd sulfate rich factor). 
Appendix B – Nonattainment Receptors 

22

3.6. Washington – Yakima County (Yakima) 

This area has not been designated nonattainment. 

EPA Region 10 PMF receptor modeling identified 10 factors contributing to elevated wintertime PM2.5 

including wood smoke (24%), nitrate rich (24%), gasoline vehicles (16%), organic pyrolysis rich (9%), 

sulfate rich (7%) and smaller contributions from other identified factors (iron rich, sea salt, soil, zinc 

rich, and urban unidentified).