Appendix B – Nonattainment Receptors

1 Technical Support Document for EPA’s Proposed Action on the State of New Mexico’s 2009 Infrastructure State Impl ementation Plan (Transport Portion) for the 2006 24-hour Fine Particulate (PM2.5) Na tional Ambient Air Quality Standard



### Appendix B – Nonattainment Receptors

1. EPA Region 9 States – California
1. Eastern California – Inyo County
2. Southern California – Los Angeles, Ri verside, and San Bernardino Counties
3. Northern California – Butte, Sacr amento, and Sutter Counties
4. Central California – Fresno, Kern, Kings, Me rced, 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 Great er 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 primar ily 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 Figur es 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 matte r, and the steep nearby terrain, it is reasonable to conclude that emissions from sour ces in New Mexico do not contribu te 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 Californi a. It is situated at the south end of the deep, long, na rrow Owens Valley with the Sierra Nevada to the west (maximum elevation 14,495 feet), the Inyo Mo untains to the east (maximum elev ation 14,246 feet), and the Coso Range to the south (maximum elevation 8,160 feet) (Figure 1.1.C). The pre dominantly 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 c ity 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 appr oximately 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 sour ce 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.htmAppendix B – Nonattainment Receptors

3 Owens lakebed produces enormous amounts of windblow n 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 wi nd-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 MapAppendix 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/m 3 . 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/m 3 . 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 so urce emissions of precursor gases (i.e., NOx, SOx, NH4, and VOC) that are c onverted to PM in the atmosphere.

Speciated PM2.5 data at the Central Los Angeles S ite (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 gene rated 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 downwi nd of an area with major ammonia sources associated with dairies and poultry farming. 6

The South Coast Air Quality DRAFT 2012 Air Quality Management Plan 7 air quality pr ojections show that the emission control strategy ou tlined in the plan will result in air quality improvement at each of the nonattainment receptors, and that each of these site s 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 f act that it is largely of local origin. The air quality trends and projections indicate that the emissi on strategy is effective in reducing PM2.5. Therefore, it is reasonable to conclude that transport from New Mexico does not contribute to violations of the 2006 PM2.5 st andard 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/2012aq mp/draft/Chapters/Ch5.pdfAppendix B – Nonattainment Receptors

7 Figure 1.2.A: Speciated data for Central Los Angeles 8

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 TrendsAppendix B – Nonattainment Receptors

10 Figure 1.2.D: Maximum 24-Hour Average PM2.5 Design Concentrations: 2008 Baseline, 2014 and 2014 Controlled 10

10 http://www.aqmd.gov/aqmp/2012aq mp/draft/Chapters/Ch5.pdfAppendix 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 most likely reflect localized sources occurring during wintertime temperat ure inversions with low winds that persist for several days in an ar ea 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 indica tes that residential wood burning emissions are the dominant source. Also, about 70% of the emissions are estimated to be from area so urces, of which residential wood burning is the dominant source, co ntributing 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 Sacr amento Metro nonattainment area.

The monitored exceedances most likely reflect localized sources occurring during wintertime temperat ure 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 ma ss is 47-60% total carbon mass (TCM), which indicates residential wood burni ng 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 Sacram ento'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/regi on9/air/trends/pm25.html ).

Sutter Yuba City Yuba City-Marysville

The monitored exceedances most likely reflect localized sources occurring during wintertime temperat ure inversions with low winds that persist for several days.

There is a strong downward tre nd and preliminary 2009-2011 data indicates the area may be attaining the standard. ( http://www.epa.gov/regi on9/air/trends/pm25.html ).Appendix B – Nonattainment Receptors

12 The Northern Sacramento Valley Air Basin is bo unded on north and west by the Coastal Mountain Range and on the east by the southern portion of th e Cascade Mountain Range and the northern portion of the Sierra Nevada Mountains. These mountain range s reach heights in excess of 6,000 feet with peaks rising much higher. This provides a substantial physical barrier to local ly created pollution.

For the areas under consideration, high PM2.5 concentr ations mostly occur during stagnant conditions during winter, with radiation invers ions. The cooling of the ground, as he at is radiated away, creates an inversion, since air near the ground is cooler than that above. Th is inhibits mixing and confines pollutants to a relatively shallo w layer near the ground. A typical value for maximum mixing height during high PM2.5 conditions is 300 meters (984 f eet) AGL (above ground level). EPA recognizes that an inversion height is not a rigi d 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 st rong diurnal slope flows. In any cas e, 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 inve rsions may be enhancing pollution concentrations, and of the extent of the area that may be contributi ng to NAAQS violations.

Because these areas in Northern California have t opographical features higher than the typical daytime height of the inversion layer, EPA c onsidered the inversion height to esti mate the size of the area likely to have similar pollution conditions and to contribu te to NAAQS violations. For example, the eastern portion of Butte County extends into the foothills of the Sierra Neva da Mountains. For Chico, the 300 meters AGL (984 feet) inversion la yer thickness translates to an el evation 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 importa nt factor in these areas, given th at 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 No rthern California receptors supports the fact that the PM2.5 is largely of local origin. Therefore, it is reasonable to conclude that transport from New Mexico does not contribute 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/ m3Appendix B – Nonattainment Receptors

14 Figure 1.3.B: Map of Butte County PM2.5 Nonattainment AreaAppendix 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 pe riods 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%) a nd organic carbon (16%).

The primary sources of PM2.5 in the region are diesel engines (nitrate), gasoline engines (nitrate), and agricultural activ ities (ammonium) which contribute regiona lly. 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 co nclude that long range transport does not contribute to elevated levels PM2.5 in the San Joaquin Valley. EPA believes it is reasonable to conc lude that New Mexico does not contribute to nonattainment of th e 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 Con centration in Bak ersfield CaliforniaAppendix B – Nonattainment Receptors

17 Figure 1.4.B: 2008-2010 Peak Day Composition in BakersfieldAppendix 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 base d on a single high value of 114 μg/m 3 , measured on June 1, 2010. Measured values of PM2.5 at the La Posta site are very low for other days. All other measured values of PM2.5 at the La Posta monitoring site are very low. On J une 1, 2010, the La Posta mon itor 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 over 700 miles from New Mexico. The monitored PM2.5 levels at the two operating monitors in Imperial County, which is located just east of San Diego County and the La Posta monitor and far west of New Mexico, on June 1, 2010 were 7.12μg/m 3 and 10.2μg/m 3

. The level of PM2.5 measured at the La Posta mon itor on June 1, 2010 appears to be from local sources, which supports our finding that emi ssions from New Mexico sources do not significantly contribute to the elevated PM2.5 leve ls at this location.

Furthermore, given the very low levels of PM2.5 m easured at all other sites in California including a monitor between NM and the La Posta monitor on th e only day the La Posta monitor has been above 35μg/m 3 , it is reasonable to conclude that there is not a significant contributi on to the elevated PM2.5 levels from emissions of PM2.5 or PM2.5 precu rsors from New Mexico to this receptor.

2. EPA Region 8 States – Montana and Utah 12

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 te mperature 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 th e other low-lying valleys ju st west of the Wasatch Front, the topography of the Utah Valley makes it pr one to temperature invers ions. 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 fr esh 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 mount ains separating these airs heds which is below the approximate average inversion height for these areas.

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

19 Speciation data from exceedance days from 2004-2006 showed the average composition of PM2.5 in Provo is 71% ammonium nitrate, wi th 21% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal.

Several factors, including signi ficant mobile, point and area sour ces contribute to primary and secondarily formed PM2.5 that viol ate the standard during stable weat her events associated with strong inversions.

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

(Site names: Brigham City, Ogde n-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 La ke 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 tran sport between the Salt La ke City and Provo NAAs) featuring stagnant air masses and light winds which t ypically oscillate back and forth within the airshed. As the airshed is essentially cappe d during inversions, PM2.5 is formed in-situ (and trapped) via fresh locally derived emission sour ces 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 signi ficant mobile, point and area sour ces contribute to primary and secondarily formed PM2.5 that viol ate the standard during stable weat her 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 a nd 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 Va lley indicates the PM2.5 pr oblem is dominated by ammonium nitrate aerosol similar to nonattainment area s 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 conditi ons 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, tran sport of PM2.5 and precursors from the rural regions at the domain periphery is very small. In addi tion, most of the observed Wasatch Front and Cache Valley PM2.5 is formed in-situ (and trapped) via fr esh locally derived emission sources and secondary chemistry.Appendix B – Nonattainment Receptors

20 Local heating emissions from woodstoves, emissions fr om agricultural activiti es, and mobile emissions contribute to primary and secondar ily formed PM2.5 that violate th e standard during stable weather events associated with ex tremely strong inversions.

These emissions and the related eff ects 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 populated with no significant sources that can contri bute to a violation of the PM2.5 standard at the Franklin monitor.

EPA Region 10 Positive Matrix Factor (PMF) recep tor modeling identified 11 factors contributing to elevated wintertime PM2.5 at the Bountiful monitori ng site including nitrate rich (56%), ammonium chloride (15%), wood smoke (10%), organic pyro lysis rich (6%), sulfat e rich (5%) and smaller contributions by other identified fact ors (gasoline vehicles, 2 soil factor s, fireworks, iron rich, and urban unidentified).

3.2. Idaho – Shoshone County (Pinehurst)

This area has not been designated nonattainment.

State information indicates that em issions from woodstoves contribute to primary PM2.5 that violates the standard during stable weather events associat ed with strong inversions . These emissions and the related effects are limited to the city of Pinehurst ai rshed, as they are trapped there due to temperature inversions, low wind a nd local topography.

The rest of the county is very sp arsely 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 designat ed nonattainment for the 2006 PM2.5 NAAQS. Klamath Falls is a relatively small urban community located in and supporting a vast rura l area in south-central Oregon.

State analysis includes a 2005 emi ssion inventory that shows that w ood stove emissions are the most significant source of emissions. Addi tional 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 D ecember through January, corresponding directly with the winter wood heating season and indicate the exceed ances are a seasonal occurrence except flagged wildfire events.

Speciation data analysis i ndicates most of the PM2.5 comes from elemental and organic carbon, typical indicators of combustion activ ities such as wood burning.

Meteorological data from Klamath Fa lls show that low wind speeds dominate during violating days, and the Klamath Falls area experiences frequent winte r-time nocturnal inversions, when PM pollution can build up over time.Appendix B – Nonattainment Receptors

21 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 th at pollution in the Klamath Falls area is a localized effect heavily influenced by the use of woodstoves.

EPA Region 10 PMF receptor modeli ng 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 contributi ng to PM2.5 including wood smoke (67%), organic pyrolysis rich (13%), nitrate rich (7%), soil (5%) and smaller co ntributions 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 w ood burning appliances as being the main contributors to fine pa rticle pollution in this area.

EPA Region 10 PMF receptor modeli ng identified 7 factors contribu ting to elevated wintertime PM2.5 including wood smoke (76%), organic pyrolysis rich (15%) and smaller contribu tions 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 associ ated with home heating is the largest source of PM2.5 in the Tacoma-Pierce C ounty nonattainment area.

The state data shows that the PM2.5 problem is highl y localized. Surface measurements at multiple sites suggest that the only design values which viol ate the 2006 PM2.5 NAAQS are in the core of the nonattainment area, within about 3 km of the Sout h L Street monitor. Be yond about 3-5km, the design values drop and are well below the NAAQS.

On-site sonic anemometer and vertical temperatur e 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 whic h 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.Appendix B – Nonattainment Receptors

22 EPA Region 10 PMF receptor modeli ng identified 10 factors contribu ting 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 (gaso line vehicles, sea salt, soil, aged sea salt, and a 2 nd sulfate rich factor).

3.6. Washington – Yakima County (Yakima)

This area has not been designated nonattainment.

EPA Region 10 PMF receptor modeli ng identified 10 factors contribu ting to elevated wintertime PM2.5 including wood smoke (24%), nitrate rich (24%), gaso line vehicles (16%), orga nic pyrolysis rich (9%), sulfate rich (7%) and smaller contributions from other identified factors (iron ri ch, sea salt, soil, zinc rich, and urban unidentified).