Chapter Four – Visibility and Source Apportionment Modeling 

4.1 INTRODUCTION 

4.1.1 Air Quality Models 

4.1.2 Model Performance Evaluation 

 4.1.2.1 2002 Worst Days Performance 

 4.1.2.2 2002 Best Days Performance 

4.1.3 Weighted Emissions Potential Analysis 

4.2 VISIBILITY MODELING RESULTS FOR 2018 

4.2.1 2018 Visibility Projections for Jarbidge Wilderness Area 

4.3 SOURCE APPORTIONMENT MODELING RESULTS 

4.3.1 Sulfate Source Apportionment for Jarbidge Wilderness Area 

4.3.2 Nitrate Source Apportionment for Jarbidge Wilderness Area 

4.3.3 Source Apportionment for Other Class I Areas 

4.3.4 Organic Aerosol Source Apportionment for Jarbidge Wilderness Area 

 4.3.4.1 Organic Aerosol PSAT for Worst Days 2002 and 2018 

 4.3.4.2 Organic Aerosol PSAT for Best Days 2002 and 2018 

 4.3.4.3 Organic Aerosol PSAT for All Days 2002 and 2018 

4.4 WEIGHTED EMISSIONS POTENTIAL ANALYSES RESULTS 

4.4.1 Nitrogen Oxides – Regional WEP Analysis for 2018 Worst Days 

4.4.2 Sulfur Oxides – Regional WEP Analysis for 2018 Worst Days 

4.4.3 Organic Carbon – Regional WEP Analysis for 2018 Worst Days 

4.4.4 Elemental Carbon – Regional WEP Analysis for 2018 Worst Days 

4.4.5 Particulate Matter Fine – Regional WEP Analysis for 2018 Worst Days 

4.4.6 Particulate Matter Coarse – Regional WEP Analysis for 2018 Worst Days 

4.5 VISIBILITY AND SOURCE APPORTIONMENT MODELING 

SUMMARY 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-1 
4.1 INTRODUCTION 

The regional haze rule (RHR) requires states to “address regional haze in each mandatory Class I 

Federal area located within the State, and each mandatory Class I Federal area located outside 

the State which may be affected by emissions from within the State”. The RHR also requires 

goals be established to “provide for reasonable progress toward achieving natural visibility 

conditions.” CFR 40 Part 51.308(d) Air quality modeling analyses were performed to determine 

which Class I areas are affected by emissions from Nevada and to evaluate reasonable progress, 

as discussed in Chapter One. The Western Regional Air Partnership’s (WRAP) Regional 

Modeling Center (RMC) performed these modeling analyses for the WRAP states, including 

Nevada. 

Visibility modeling results indicate that the Jarbidge Wilderness Area (Jarbidge WA) will meet 

the Uniform Rate of Progress (URP) for 2018. The modeling results and technical analyses also 

indicate Nevada sources do contribute to visibility impairment at the Jarbidge WA, as well as 

Class I areas located in adjacent states. The modeling also indicates that out-of-state sources 

have the greatest impact on regional haze in Nevada. Regional weighted emissions potential 

(WEP) analyses indicate the significant role of emissions from wind blown and fugitive dust and 

natural fire in visibility impairment at the Jarbidge WA, thereby supporting the anecdotal 

observations of the Nevada Division of Environmental Protection (NDEP) staff discussed in 

Chapter One. 

The visibility and source apportionment modeling described in this Chapter provides, in 

conjunction with the monitoring and emissions analyses, the technical basis used to identify and 

evaluate reasonable progress for the Jarbidge WA. 

4.1.1 Air Quality Models 

RMC utilized two grid-based models to analyze the effects of haze-causing particles within the 

WRAP area. The Community Multi-Scale Air Quality (CMAQ) model provided visibility 

modeling forecasts for 2018, the end of the first regional haze planning period. The results of 

CMAQ modeling are used in identifying the 2018 reasonable progress goals (RPG). The 

Particulate Matter Source Attribution Tracking (PSAT) algorithm in the Comprehensive Air 

Quality Model with Extensions (CAMx) model is used to assess source apportionment, 

particularly for sulfate and nitrate particle species, based on source area and source category, and 

to identify those Class I areas that are affected by Nevada emission sources. 

The PSAT algorithm applies nitrate-sulfate-ammonia chemistry to a system of tracers, or “tags”, 

to track chemical transformations, transport and removal of emissions. Each source area (state or 

region) is assigned a tag that is used to track the emissions from each 36-kilometer grid cell 

within the specified source area. Emissions from point, mobile, area and fire (natural and 

anthropogenic) source categories were tagged for each source area. The PSAT algorithm was 

also used, in a limited application (i.e., no source area attribution), to track natural and 

anthropogenic species of organic aerosols at each Class I area. The organic aerosol tracer 

tracked both primary and secondary organic aerosols (POA and SOA, respectively). 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-2 
Meteorological inputs and emission inventories were prepared for 2002, chosen as representative 

of the baseline period 2000 through 2004. These inputs were used in the air quality model to 

predict fine particle mass and visibility. The model results for 2002 were compared with 

observed meteorological and air quality data to evaluate model performance. Several 

configurations of the meteorological and air quality model were evaluated to select the 

configuration that gave the best overall performance for the WRAP region. Once model 

performance was deemed adequate, the current and future year emissions were processed 

through the emissions model, as discussed in Chapter One. The modeled emissions scenarios are 

described in Chapters One and Three. 

4.1.2 Model Performance Evaluation 

The objective of the model performance evaluation was to compare model-simulated 

concentrations with observed data to determine whether the model’s performance was 

sufficiently accurate to justify using the model for simulating future conditions, as discussed in 

Chapter One. The model was compared to ambient data for both particulate matter and gaseous 

species, for an annual time period and for a large number of sites. The model was evaluated for 

both the worst and best visibility conditions. The “Final Report for the WRAP 2002 Visibility 

Model Performance Evaluation” (Tonnesen, et al, 2006 can be found at 

http://pah.cert.ucr.edu/aqm/308/reports/final/2002_MPE_report_main_body_FINAL.pdf) 

discusses in detail how the model performance was evaluated. 

The WRAP’s RMC found the model over-predicted the observed data on the cleanest days (i.e., 

the 20 percent best days or best days) and under predicted the observed data on the most polluted 

days (i.e., the 20 percent worst days or worst days). 

RMC has concluded that the CMAQ model cannot be used to forecast future coarse matter (CM) 

concentrations. Nevada has also deemed model performance was unacceptable for fine 

particulate matter (SOIL) on the worst days and nitrate on the best days. Model performance is 

discussed in greater detail below. 

4.1.2.1 2002 Worst Days Performance 

CMAQ model performance can be roughly judged by comparing the model predicted 

concentration (left side of Figure 4-1) against the monitored concentration from the Interagency 

Monitoring of Protected Visual Environments (IMPROVE) monitor JARB1 (right side of Figure 

4-1) for the worst days of 2002. As shown, the model greatly under-predicts total mass and 

particularly CM (shown in gray on Figure 4-1). Similar model under-prediction is observed 

across the WRAP region, thus the RMC has concluded that the CMAQ model cannot be used to 

forecast future CM concentrations. 

Figure 4-2 indicates the CMAQ model under predicts, as shown by negative percentages, all six 

components of extinction for the worst days at JARB1. Nevada deems model performance for 

the worst days is acceptable for sulfate (-32 percent), nitrate (-20 percent), organic matter (-40 

percent), and elemental carbon (-33 percent), but is unacceptable for SOIL (-88 percent). 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-3 
FIGURE 4-1 

CMAQ MODEL PERFORMANCE FOR JARB1 2002 WORST DAYS

FIGURE 4-2 

RELATIVE ERROR OF CMAQ MODEL PREDICTION VERSUS 

 IMPROVE DATA FOR JARB1 2002 WORST DAYS

-100%

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

Sulfate Nitrate OMC EC Soil CM

R

elative E

rror (

%)

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-4 
4.1.2.2 2002 Best Days Performance 

Comparison of the model predicted concentration (left side of Figure 4-3) against the monitored 

concentration from the IMPROVE monitor JARB1 (right side of Figure 4-3) for the best days of 

2002 shows much better agreement between total mass. 

FIGURE 4-3 

CMAQ MODEL PERFORMANCE FOR JARB1 2002 BEST DAYS

However, Figure 4-4 shows the model produces mixed predictions for the best days at JARB1. 

Nevada deems the model performance for the best days is acceptable for elemental carbon (-33 

percent) and SOIL (-38 percent), but is marginally acceptable for sulfate (+61 percent) and 

organic matter (+60 percent). Model performance for nitrate (+175 percent) is unacceptable for 

the best days. As described above, RMC has concluded the CMAQ model cannot be used to 

predict future CM concentrations. 

4.1.3 Weighted Emissions Potential Analysis 

The WEP was developed as a screening tool for states to identify which source areas (e.g., states) 

have the potential to contribute to haze formation at specific Class I areas, based on both the 

2002 and 2018 emissions inventories, as discussed in Chapter One. WEP was used to investigate 

the attribution of sources of nitrogen oxides (NOx), sulfur dioxide (SO2), organic carbon (OC), 

elemental carbon (EC), fine particulate matter (PMF) and coarse particulate matter (PMC). The 

results of the WEP analyses are discussed below in section 4.4. 

4.2 VISIBILITY MODELING RESULTS FOR 2018 

Visibility modeling results indicate projected visibility conditions for the Jarbidge WA, based on 

the PRP18a emission inventory, will meet the URP for 2018 (i.e., 2018 projected visibility 

conditions show better progress than the glidepath). 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-5 
FIGURE 4-4 

RELATIVE ERROR OF CMAQ MODEL PREDICTION VERSUS 

 IMPROVE DATA FOR JARB1 2002 BEST DAYS

-100%

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

200%

Sulfate Nitrate OMC EC Soil CM

R

elati

v

e E

r

r

o

r (%)

4.2.1 2018 Visibility Projections for Jarbidge Wilderness Area 

Table 4-1 lists the 2018 URP for the Jarbidge WA and the CMAQ visibility modeling forecasts 

for 2018. The results of this modeling will be used in establishing RPGs for the Jarbidge WA. 

The 2018 model forecasts indicate Jarbidge WA will meet the 2018 URP for the 20 percent 

worst days and will maintain visibility for the best days in 2018. 

The 2018 modeling results of 11.05 deciviews (dv) presented in Table 4-1 and Figure 4-5 show 

an improvement of 1.02 dv from the worst days baseline value of 12.07 dv for the Jarbidge WA

using the USEPA specific days method. This results in an improvement of 4.1 percent over the 

2018 URP value of 11.09 dv, or 104.1 percent toward the 2018 URP. This indicates that 

Nevada’s projected reasonable progress is better than the URP. The visibility model projections 

are based on the 2018 preliminary reasonable progress (PRP18a) emission inventory identified in 

Chapter Three. The 2018 PRP does not include all of Nevada’s Best Available Retrofit 

Technology (BART) emission controls, or all of adjacent states’ BART controls. Additional 

emission reductions due to the installation of BART and other controls under the RHR are 

anticipated to improve modeled visibility forecasts. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-6 
TABLE 4-1

SUMMARY OF MODEL-PREDICTED PROGRESS 

TOWARD 2018 UNIFORM RATE OF PROGRESS AT JARB1

20 Percent Worst Days 20 Percent Best Days 

Mandatory 

Class I 

Federal 

Area 

Worst

Days 

Baseline 

(dv) 

2018 URP 

(dv) 

2018 

Modeling 

Results 

(dv) 

CMAQ 

Modeling 

Percent 

Toward 

2018 

URP 

Best Days 

Baseline 

(dv) 

Average 

2018 

Modeling 

Results 

(dv) 

CMAQ 

2018 

Modeling 

Result 

Less 

Than 

Baseline?

Jarbidge 

Wilderness 

Area 

12.07 11.09 11.05 104.1% 2.56 2.50 Yes

FIGURE 4-5 

CMAQ MODEL PROJECTIONS IN HAZE INDEX 

FOR JARB1 2018 WORST DAYS

Figure 4-6 provides the species-specific extinction glide slopes in inverse megameters and 

corresponding 2018 model projections for the worst days at JARB1 using the USEPA specific 

days method. Table 4-2 presents these data graphically and identifies the 2018 URP, the modelprojected 2018 extinction and the percentage of modeled progress from the baseline toward the 

2018 URP. The values presented in Figures 4-5 and 4-6 are rounded to one decimal place, while 

those in Table 4-2 are presented to two decimal places. 

All components show extinction reductions from baseline conditions, except CM and Sea Salt 

extinctions. These two remain constant from the baseline period to 2018 because the emission 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-7 
inventories for these components were held constant for the baseline period and the 2018 

projection for the purposes of modeling. 

Projected 2018 extinction meets the URP for all components except SO4 and Soil, as shown in 

Figure 4-6 and indicated by modeled extinction changes of greater than 100 percent in Table 4-2. 

The projected SO4 extinction of 3.34 Mm-1 achieves 80 percent of the 2018 URP value (3.17 

Mm-1). The projected NO3 extinction of 0.7 Mm

-1 shows an improvement of 1000 percent 

toward the 2018 URP of 1.06 Mm-1. 

Recall that the RMC has indicated the CMAQ model cannot be used to forecast future CM 

concentrations, and NDEP has deemed the model performance for Soil on the worst days as 

unacceptable. The results for these species are presented for informational purposes. 

FIGURE 4-6 

CMAQ MODEL PROJECTIONS IN EXTINCTION 

BY SPECIES FOR JARB1 2018 WORST DAYS

TABLE 4-2

SUMMARY OF MODEL PREDICTED PROGRESS TOWARD 

SPECIES-SPECIFIC 2018 WORST DAYS URP AT JARB1

Extinction (Mm

-1) Sulfate Nitrate

Organic

Carbon

Elemental 

Carbon Fine Soil

Coarse

Mass Sea Salt

Baseline 4 1.1 10.04 1.65 2.41 5.47 0.06

2018 URP 3.17 1.06 8.49 1.34 2.15 5.2 0.13

Projected 2018 RP 3.34 0.7 8.24 1.12 2.29 5.47 0.06

Modeled Change from

Baseline to 2018 URP 

(% of Goal)

80% 1000% 116% 171% 46% 0% 0%

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-8 
Figure 4-7 indicates the 2018 model-projected extinction for the best days at JARB1, using the 

USEPA specific days method, is 2.50 dv, which is below the best days baseline average of 2.56 

dv. These data indicate Nevada is forecast to maintain visibility for the best days of 2018 at the 

Jarbidge WA. 

FIGURE 4-7 

CMAQ MODEL PROJECTIONS IN HAZE INDEX FOR JARB1 2018 BEST DAYS

4.3 SOURCE APPORTIONMENT MODELING RESULTS 

The PSAT algorithm in the CAMx model was developed to assess source apportionment. The 

PSAT analysis was used to attribute particle species, particularly sulfate and nitrate, from

specific source areas and source categories, as discussed earlier. Emissions from each state or 

region for point, mobile, area and fire sources were tagged and tracked. The PSAT modeling 

utilized the Plan02c and Base18b emission inventories. 

4.3.1 Sulfate Source Apportionment for Jarbidge Wilderness Area 

Figure 4-8 displays the 2002 and 2018 worst days particulate sulfate concentrations impacting 

the JARB1 monitor due to emissions from WRAP states. The chart provides details on the 

relative source contribution for each WRAP state during 2002 and 2018. The data indicate the 

overall SO2 emission sources for the worst days are from the states of Idaho, Oregon and 

Washington. Idaho’s contributions to sulfate are primarily from natural fire emissions which 

were held constant from 2002 to 2018. Point sources also contribute significantly to sulfate from

Idaho. Washington, Oregon, Nevada and California show contributions to sulfate primarily from

point sources and natural fires. 

Figure 4-9 shows the contributions to sulfate concentration from all modeled source areas for the 

worst days of 2002 and 2018 at the JARB1 monitor. These charts show that source areas outside 

the domain and within the WRAP region have sub-equal contributions of approximately 40 

percent to year 2002 sulfate concentration at the JARB1 monitor for the worst days. Adding 

other source area contributions outside of the United States (i.e., Canada, Mexico and Pacific 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-9 
Offshore) to the Outside Domain source area contributions suggests over 55 percent of the 

sulfate contributions to visibility impairment at the Jarbidge WA are outside the jurisdiction of 

state or federal regulation. 

FIGURE 4-8 

SULFATE PSAT SOURCE REGION BAR 

CHART FOR WORST DAYS 2002 AND 2018

FIGURE 4-9 

SULFATE PSAT REGIONAL PIE CHART FOR WORST DAYS 2002 AND 2018

Figure 4-10 displays the 2002 and 2018 best days’ particulate sulfate concentrations impacting 

the JARB1 monitor due to emissions from WRAP states. The chart provides details on the 

relative source contribution for each WRAP state during 2002 and 2018. The data indicate the 

dominant WRAP source area contribution for the best days is Nevada. Lesser contributions are 

due to emissions from Idaho, Oregon and California. Point sources are the dominant source 

category. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-10 
Figure 4-11 show the contributions to sulfate concentration from all modeled source areas for the 

best days of 2002 and 2018 at the JARB1 monitor. These charts show that WRAP source areas 

contribute less than a third to the sulfate concentration at the JARB1 monitor for the best days. 

Source areas outside the jurisdiction of state or federal regulation and/or control (i.e., Outside 

Domain, Canada, Mexico and Pacific Offshore) contribute more that two thirds to the sulfate 

concentration at the JARB1 monitor. 

FIGURE 4-10 

SULFATE PSAT SOURCE REGION BAR CHART FOR BEST DAYS 2002 AND 2018

FIGURE 4-11 

SULFATE PSAT REGIONAL PIE CHART FOR BEST DAYS 2002 AND 2018

4.3.2 Nitrate Source Apportionment for Jarbidge Wilderness Area 

Figure 4-12 displays the particulate nitrate concentrations for 2002 and 2018 worst days for 

WRAP source areas at the JARB1 monitor. The chart provides details on the relative source 

contribution of each WRAP state during 2002 and 2018. The data indicate the dominant WRAP 

source area contributions for the worst days are from Idaho, Utah and Nevada. California, 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-11 
Oregon and Washington had lesser contributions to nitrate concentrations at the JARB1 monitor. 

Mobile source emissions are the dominant source category for NOx emissions, although area 

source emissions are significant for Idaho. Point source emissions from Idaho, Nevada and Utah 

are also important contributors to the modeled nitrate concentration for the worst days of 2002 

and 2018. 

FIGURE 4-12 

NITRATE PSAT SOURCE REGION BAR CHART FOR WORST DAYS 2002 AND 2018

Figure 4-13 shows the contributions to nitrate concentration from all modeled source areas for 

the worst days of 2002 and 2018 at the JARB1 monitor. The pie charts show the WRAP region 

contributes more than three quarters to 2002 nitrate concentration at the JARB1 monitor for the 

worst days of 2002. The WRAP contribution drops to more than two thirds for 2018. Outside 

Domain sources combined with contributions from Mexico, Canada and Pacific Offshore areas 

contribute nearly a quarter to sulfate concentrations at the JARB1 monitor in 2002. 

Contributions from these sources increase to nearly a third for 2018. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-12 
FIGURE 4-13 

NITRATE PSAT REGIONAL PIE CHART FOR WORST DAYS 2002 AND 2018

Figure 4-14 displays the 2002 and 2018 best days’ particulate nitrate concentrations impacting 

the JARB1 monitor due to emissions from WRAP states. The chart provides details on the 

relative source contribution for each WRAP state during 2002 and 2018. The data indicate the 

dominant WRAP source area contribution for the best days is the State of Nevada with 

significant contributions from California and Idaho. Oregon, Utah and Washington show lesser 

contributions. Mobile sources are the dominant source category, except in Nevada, where point 

and mobile sources have sub-equal contribution to nitrate concentration at the JARB1 monitor. 

Area sources in Idaho also contribute significantly. 

FIGURE 4-14 

NITRATE PSAT SOURCE REGION BAR CHART FOR BEST DAYS 2002 AND 2018

Figure 4-15 displays the contributions to nitrate concentration from all modeled source areas for 

2002 and 2018 best days at JARB1. The pie charts indicate WRAP states contribute 

approximately two thirds to the nitrate concentration at the JARB1 monitor with the remaining 

nitrate impact due to Outside Domain, Canada and Pacific Offshore sources. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-13 
FIGURE 4-15 

NITRATE PSAT REGIONAL PIE CHART FOR BEST DAYS 2002 AND 2018

4.3.3 Source Apportionment for Other Class I Areas 

The PSAT source apportionment modeling results were evaluated to determine which Class I 

areas in adjacent states might be affected by emissions from Nevada sources. Table 4-3 presents 

the results of this evaluation for sulfate extinction. The table identifies the rank and percentage 

of the total modeled concentration due to SO2 emissions from sources within Nevada to the 

IMPROVE monitors representing all Class I areas in the five adjacent states. The rank and 

percentage contribution is based on contributions from all modeled source areas. The bolded 

values are the highest percentage contribution to visibility impairment at Class I areas in each of 

the five adjacent states due to emissions from Nevada sources for the worst days projected for 

2018. 

Examination of the best days 2018 rank and contribution identifies the maximum contribution to 

sulfate extinction due to emissions from Nevada sources occurs at SAWT1 located in the 

Sawtooth Wilderness Area, with a rank of 4 and a contribution of 7.2 percent. For the worst 

days, Nevada’s maximum contribution occurs at ZION1 located in Zion National Park with a 

rank of 6 and a contribution of 5.6 percent. Figure 4-16 shows SO2 emissions from sources 

outside the modeling domain, which are beyond the jurisdiction of United States regulatory 

agencies and uncontrollable, contribute nearly eight times as much as Nevada sources to sulfate 

extinction on the 2018 best days at the Sawtooth Wilderness Area. Figure 4-17 shows the two 

source areas with the greatest contributions to sulfate extinction on the 2018 worst days to Zion 

National Park are Outside Domain and Pacific Offshore. Sources in Mexico are the fourth 

largest contributor while the majority of emissions from the third largest source area contributor 

are natural. 

Table 4-4 presents the results of the source apportionment modeling for nitrate extinction at the 

Class I areas in adjacent states. Examination of the best days 2018 rank and contribution 

identifies the maximum contribution to nitrate extinction due to emissions from Nevada sources 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-14 
occurs at JOSH1 located in Joshua Tree National Park, with a rank of 4 and a contribution of 

12.4 percent. For the worst days, Nevada’s maximum contribution occurs at BLIS1 located in 

Bliss State Park (monitor location for Desolation Wilderness Area and Mokelumne Wilderness 

Area) with a rank of 3 and a contribution of 20.0 percent. The bolded values in this table 

represent the maximum visibility impacts at the Class I areas in adjacent states due to Nevada’s 

emissions for the worst days projected for 2018. 

 

TABLE 4-3

NEVADA’S SULFATE EXTINCTION CONTRIBUTION TO 

CLASS I AREAS OUTSIDE OF NEVADA

Impact Rank Impact Rank Impact Rank Impact Rank

GRCA2 Hance Camp 3.1% 4 2.8% 5 6.0% 6 2.8% 6

IKBA1 Ike's Backbone 4.2% 6 2.6% 8 3.3% 8 1.5% 10

SIAN1 Sierra Ancha 2.6% 9 1.6% 9 3.1% 8 1.5% 9

SYCA1 Sycamore Canyon 6.3% 3 3.1% 6 5.6% 6 2.5% 8

TONT1 Tonto 2.2% 7 1.3% 9 2.7% 8 1.3% 9

BLIS1 Bliss State Park 3.0% 4 3.1% 4 4.8% 5 4.4% 5

DOME1 Dome Lands 6.3% 3 5.3% 3 2.0% 7 1.6% 8

HOOV1 Hoover 2.3% 4 2.2% 4 3.0% 6 2.6% 6

JOSH1 Joshua Tree 6.6% 4 4.0% 4 1.7% 6 1.2% 6

KAIS1 Kaiser 1.6% 4 1.5% 4 2.9% 6 2.4% 6

LAVO1 Lassen Volcanic 2.7% 4 3.0% 4 2.1% 7 2.3% 7

LABE1 Lava Beds 3.5% 4 3.8% 4 3.1% 7 3.2% 7

SAGA1 San Gabriel 2.4% 4 2.0% 4 1.0% 7 0.7% 8

SAGO1 San Gorgonio 6.9% 4 4.1% 5 1.5% 6 0.9% 6

SEQU1 Sequoia 3.1% 4 2.2% 5 2.8% 5 2.0% 5

YOSE1 Yosemite 2.9% 6 2.4% 7 1.9% 4 1.6% 4

CRMO1 Craters of the Moon 3.5% 7 4.1% 6 1.6% 9 1.9% 9

SAWT1 Sawtooth 5.9% 5 7.2% 4 2.2% 8 2.5% 8

CRLA1 Crater Lake 0.8% 7 0.8% 7 1.2% 7 1.4% 7

HECA1 Hells Canyon 1.2% 8 1.6% 5 3.2% 7 4.0% 6

STAR1 Starkey 1.6% 7 1.9% 7 1.7% 7 2.0% 7

BRCA1 Bryce Canyon 3.8% 3 4.1% 4 8.1% 5 4.8% 6

CAPI1 Capitol Reef 2.4% 8 2.5% 8 6.0% 6 3.9% 6

ZION1 Zion 5.4% 3 4.9% 3 9.0% 4 5.6% 6

Utah

IMPROVE

Site Code

IMPROVE 

Site Name

Arizona

California

Idaho

Oregon

Sulfate Extinction Contribution due to Nevada Emissions

Best Days Worst Days

2002 2018 2002 2018

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-15 
FIGURE 4-16 

SULFATE PSAT SOURCE REGION BAR CHART FOR BEST DAYS 

2002 AND 2018 AT SAWTOOTH WILDERNESS AREA

FIGURE 4-17 

SULFATE PSAT SOURCE REGION BAR CHART FOR WORST DAYS 

2002 AND 2018 AT ZION NATIONAL PARK

Figure 4-18 shows NOx emissions from California sources are the dominant contributor to nitrate 

extinction on the 2018 best days at Joshua Tree National Park, followed by sources outside the 

modeling domain and Pacific offshore sources. Figure 4-19 shows NOx emissions from 

California sources are the dominant contributor for the 2018 worst days, followed by emissions 

from sources outside the modeling domain to nitrate extinction at the Desolation Wilderness 

Area. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-16 
TABLE 4-4

NEVADA’S NITRATE EXTINCTION CONTRIBUTION TO 

CLASS I AREAS OUTSIDE OF NEVADA

Impact Rank Impact Rank Impact Rank Impact Rank

GRCA2 Hance Camp 5.8% 5 5.8% 5 2.2% 6 2.8% 6

IKBA1 Ike's Backbone 2.8% 6 3.2% 6 1.6% 8 2.4% 8

SIAN1 Sierra Ancha 2.3% 7 2.7% 7 2.6% 5 3.9% 5

SYCA1 Sycamore Canyon 3.4% 6 4.3% 6 3.4% 6 4.3% 6

TONT1 Tonto 2.4% 6 2.7% 6 1.5% 7 2.1% 7

BLIS1 Bliss State Park 4.2% 4 4.9% 4 16.3% 3 20.0% 3

DOME1 Dome Lands 8.6% 3 9.6% 3 1.8% 4 2.3% 4

HOOV1 Hoover 4.3% 3 4.8% 3 7.7% 3 8.3% 3

JOSH1 Joshua Tree 11.0% 4 12.4% 4 0.6% 4 0.6% 4

KAIS1 Kaiser 2.3% 4 2.7% 4 2.9% 6 4.0% 4

LAVO1 Lassen Volcanic 3.6% 4 4.8% 4 2.4% 6 3.0% 5

LABE1 Lava Beds 3.7% 5 4.4% 5 6.6% 4 8.0% 4

SAGA1 San Gabriel 2.0% 4 2.4% 4 0.3% 6 0.4% 5

SAGO1 San Gorgonio 5.4% 4 6.4% 4 0.3% 5 0.5% 5

SEQU1 Sequoia 2.7% 4 3.6% 4 1.6% 4 2.0% 4

YOSE1 Yosemite 1.8% 4 2.2% 4 3.8% 4 5.1% 4

CRMO1 Craters of the Moon 5.8% 8 6.6% 5 2.3% 9 2.7% 8

SAWT1 Sawtooth 6.5% 5 7.5% 5 3.1% 7 3.2% 6

CRLA1 Crater Lake 1.2% 6 1.5% 7 1.6% 7 2.0% 7

HECA1 Hells Canyon 2.0% 8 2.4% 8 4.8% 6 5.5% 5

STAR1 Starkey 3.2% 6 3.7% 6 3.7% 7 4.5% 6

BRCA1 Bryce Canyon 4.0% 4 4.0% 5 8.8% 4 8.8% 4

CAPI1 Capitol Reef 2.9% 5 2.9% 6 5.2% 4 5.4% 5

ZION1 Zion 6.2% 4 6.2% 5 8.1% 4 7.9% 4

California

Idaho

Oregon

Utah

IMPROVE 2018

Site Code

IMPROVE 

Site Name

Arizona

Nitrate Extinction Contribution due to Nevada Emissions

Best Days Worst Days

2002 2018 2002

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-17 
FIGURE 4-18 

NITRATE PSAT SOURCE REGION BAR CHART FOR BEST DAYS 

2002 AND 2018 AT JOSHUA TREE NATIONAL PARK

FIGURE 4-19 

NITRATE PSAT SOURCE REGION BAR CHART FOR WORST DAYS 

2002 AND 2018 AT DESOLATION WILDERNESS AREA

4.3.4 Organic Aerosol Source Apportionment for Jarbidge Wilderness Area 

The PSAT algorithm was also used in a limited application to track natural and anthropogenic 

species of organic aerosols at each Class I area. Source area (e.g., no state or regional) 

attribution was not performed for the aerosol source apportionment. The organic aerosol tracer 

tracked both POA and SOA. POAs are primary organics resulting form direct organic aerosol 

emissions from anthropogenic and biogenic sources. SOAs are further subdivided to include 

anthropogenic secondary organics resulting form aromatic VOCs such as xylene, toluene and 

cresols, as well as biogenic secondary organics resulting from biogenic VOCs such as terpenes. 

The purpose of the organic aerosol tracer tool is to investigate the contribution of primary and 

secondary anthropogenic and biogenic sources on modeled OC at Class I areas. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-18 
A wide variety of sources contribute to POAs, from cooking of meat to diesel emissions and 

combustion byproducts from wood and agricultural burning (e.g., emissions from area sources, 

on-road and off-road mobile sources, fugitive dust sources and fire sources). Nevada’s POA 

emissions inventory is dominated by natural fire emissions as described in Chapter 3 (see 3.8.4) 

and shown in Figure 3-17 and Table 3-10. 

4.3.4.1 Organic Aerosol PSAT for Worst Days 2002 and 2018 

Figure 4-20 displays the monthly organic aerosol concentration for the baseline period (2000 

through 2004) and 2018 in pairs for the worst days at the JARB1 monitor. The organic aerosol 

PSAT tracks anthropogenic SOA (in red), biogenic SOA (in sky blue) and 

anthropogenic/biogenic POA (in blue). The chart provides details on the relative anthropogenic 

and biogenic concentration for each month of the baseline period and the future contribution in 

2018. None of the worst days for the baseline period or for 2018 occurred during the winter or 

early spring months of January, February or March. 

FIGURE 4-20 

MONTHLY ORGANIC AEROSOL PSAT BAR CHART FOR 

WORST DAYS 2002 AND 2018

4.3.4.2 Organic Aerosol PSAT for Best Days 2002 and 2018 

Figure 4-21 displays the monthly organic aerosol concentration for the baseline period (2000 

through 2004) and 2018 for the best days at the JARB1 monitor. None of the best days during 

the baseline period or for 2018 occurred in the summer or early fall months of June, July, 

August, September or October. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-19 
FIGURE 4-21 

MONTHLY ORGANIC AEROSOL PSAT BAR CHART FOR BEST DAYS 2002 AND 2018

4.3.4.3 Organic Aerosol PSAT for All Days 2002 and 2018 

Figure 4-22 displays the monthly organic aerosol concentrations for the baseline period (2000 

through 2004) and 2018 for all days at the JARB1 monitor. This figure shows the strong 

seasonal influence of biogenic and fire emissions on visibility at the Jarbidge WA. The bar chart 

indicates biogenic SOA (in sky blue) is the dominant source of organic aerosol for all months of 

the year and it occurs at much higher concentrations during the summer and early fall months of 

June, July, August, September and October when temperatures are warmer and vegetative 

growth is most prolific. Significant POA concentrations are indicative of the contribution of 

natural fire emissions occurring in the months of July, August, September and to a lesser degree 

October. 

4.4 WEIGHTED EMISSIONS POTENTIAL ANALYSES RESULTS 

The Weighted Emissions Potential (WEP) tool is an analysis technique that identifies the 

predominant emission source regions contributing haze-forming pollutants at each Class I area 

based on 5 years of historical meteorology for both the 20 percent best and worst days, as 

described in Chapter One. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-20 
FIGURE 4-22 

ORGANIC AEROSOL PSAT BAR CHART FOR ALL DAYS 2002 AND 2018

The WEP analysis results in two graphical displays of the data: WEP maps of normalized, 

weighted emissions; and WEP bar charts of normalized, residence time- and distance-weighted 

annual emissions. The maps show the location of the Jarbidge WA with a green star surrounded 

by 100 km and 200 km radius concentric circles. The areas shaded in different colors identify 

those 36 km grid cells with the potential of contributing emissions to JARB1 for the worst days 

in 2018. Geographical regions and individual grid cells with greater potential to impact the 

Jarbidge WA are easily distinguished in the maps by the darker shaded grid cells, while the white

areas denote those grid cells with negligible emission potential. 

Geographic source areas and source categories are also easily distinguished on the bar charts, 

which identify twelve source categories: windblown dust, fugitive dust, road dust, off-road 

mobile, on-road mobile, off-shore, oil and gas, area, biogenic, natural fire, anthropogenic fire and 

point. Two different modeling simulation emission scenarios (using the Plan02d and PRP18a 

emission inventories) were used to produce the WEP maps. Only the PRP18a emission scenario 

maps for the worst days are presented below. 

4.4.1 Nitrogen Oxides – Regional WEP Analysis for 2018 Worst Days 

Figure 4-23 shows the normalized regional contributions to residence time- and distanceweighted NOx emissions for JARB1. The WEP bar charts, shown as Figure 4-24, display 

normalized (unitless), residence time- and distance-weighted 2018 annual NOx emissions values, 

by emissions source region. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-21 
FIGURE 4-23 

REGIONAL NOx WEP FOR 2018 WORST DAYS

Examination of Figures 4-23 and 4-24 shows the point source contributions from the 

industrialized portions of northern Nevada and along the Snake River Plain of Idaho, as well as 

more distance areas in southern Nevada and portions of California, including the Bay Area, 

Central Valley and Los Angeles area to 2018 NOx concentration at JARB1. These figures also 

show the contribution of mobile sources, both on-road and off-road, from the main transportation 

corridors and population centers along I-80 in Nevada and Utah, I-84 in Utah, Idaho, and 

Oregon, and I-5 in California to NOx emissions at JARB1. 

4.4.2 Sulfur Oxides – Regional WEP Analysis for 2018 Worst Days 

Figure 4-25 shows the normalized regional contributions to residence time- and distanceweighted SO2 emissions for JARB1. The WEP bar charts, shown as Figure 4-26, display 

normalized (unitless), residence time- and distance-weighted annual SO2 emissions values, by 

emissions source region. Examination of Figures 4-25 and 4-26 shows the large point source 

contributions from the industrialized portions of northeastern Nevada and along the Snake River 

Plain of Idaho, as well as more distance areas in the Bay Area of California to 2018 SO2

concentration at JARB1. These figures also show the contribution of natural fires in Idaho to 

SO2 emissions at JARB1. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-22 
FIGURE 4-24 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING NOx

EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

4.4.3 Organic Carbon – Regional WEP Analysis for 2018 Worst Days 

Figure 4-27 shows the normalized regional contributions to residence time- and distanceweighted organic carbon (POA) emissions for JARB1. The WEP bar charts, shown as Figure 4-

28, display normalized (unitless), residence time- and distance-weighted annual OC emissions 

values, by emissions source region. Examination of Figures 4-27 and 4-28 shows the large, 

natural fire source contributions from diffuse areas of California, Idaho, northern Nevada, 

Oregon, Utah and Washington to 2018 OC concentration at JARB1. These figures also show the 

contribution of area sources from population centers along the Snake River Plain of Idaho, the 

Central Valley and Bay Area of California, the Portland area of Oregon and the Seattle area of 

Washington. 

4.4.4 Elemental Carbon – Regional WEP Analysis for 2018 Worst Days 

Figure 4-29 shows the normalized regional contributions to residence time- and distanceweighted primary EC emissions for JARB1. The WEP bar charts, shown as Figure 4-30, display 

normalized (unitless), residence time- and distance-weighted annual primary EC emissions 

values, by emissions source region. The contribution distribution shown by EC is very similar to 

that shown by OC. Examination of Figures 4-29 and 4-30 shows the large, natural fire-source 

contributions from diffuse areas of California, Idaho, northern Nevada, Oregon, Utah and 

Washington to 2018 EC concentration at JARB1. Figure 3-22 in Chapter Three more clearly 

shows that the EC emissions in Nevada are primarily due to natural fire events. These figures 

also show the contribution of area and off-road mobile sources from population centers along the 

Snake River Plain of Idaho, the Central Valley and Bay Area of California, the Portland area of 

Oregon and the Seattle area of Washington. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-23 
FIGURE 4-25 

REGIONAL SO2 WEP FOR 2018 WORST DAYS

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-24 
FIGURE 4-26 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING SO2

EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

FIGURE 4-27 

REGIONAL ORGANIC CARBON WEP FOR 2018 WORST DAYS

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-25 
FIGURE 4-28 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING ORGANIC 

CARBON EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

FIGURE 4-29 

REGIONAL ELEMENTAL CARBON WEP FOR 2018 WORST DAYS

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-26 
FIGURE 4-30 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING ELEMENTAL 

CARBON EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

4.4.5 Particulate Matter Fine – Regional WEP Analysis for 2018 Worst Days 

Figure 4-31 shows the normalized regional contributions to residence time- and distanceweighted PMF emissions for JARB1. The WEP bar charts, shown as Figure 4-32, display 

normalized (unitless), residence time- and distance-weighted annual PMF emissions values, by 

emissions source region. 

Examination of Figures 4-31 and 4-32 shows the large windblown dust-source contributions 

from diffuse areas of southern Idaho, northern Nevada, eastern Oregon and northern Utah to 

2018 PMF concentration at JARB1. These figures also show lesser fugitive dust contributions 

from the same diffuse areas of Idaho, Nevada, Oregon and Washington, as well as the 

contribution of area sources from population centers along the Snake River Plain of Idaho, the 

Central Valley and Bay Area of California, and the Portland area of Oregon. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-27 
FIGURE 4-31 

REGIONAL PARTICULATE MATTER FINE WEP FOR 2018 WORST DAYS

FIGURE 4-32 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING PARTICULATE 

MATTER FINE EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-28 
4.4.6 Particulate Matter Coarse – Regional WEP Analysis for 2018 Worst Days 

Figure 4-33 shows the normalized regional contributions to residence time- and distanceweighted PMC emissions for JARB1. The WEP bar charts, shown as Figure 4-34, display 

normalized (unitless), residence time- and distance-weighted annual PMC emissions values, by 

emissions source region. The contribution distribution shown by PMC is very similar to that 

shown by PMF. Examination of Figures 4-33 and 4-34 shows the large windblown dust source 

contributions from diffuse areas of southern Idaho, northern Nevada, eastern Oregon and 

northern Utah to 2018 PMF concentration at JARB1. These figures also show lesser fugitive 

dust contributions from the same diffuse areas of Idaho, Nevada, Oregon and Washington, as 

well as the contribution of area sources from population centers along the Snake River Plain of 

Idaho, the Central Valley and Bay Area of California, and the Portland area of Oregon. Road 

dust is an important contributor from areas of California and Idaho. 

FIGURE 4-33 

REGIONAL PARTICULATE MATTER COARSE WEP FOR 2018 WORST DAYS

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-29 
FIGURE 4-34 

SOURCES AND AREAS OF POTENTIAL HAZE-CAUSING PARTICULATE 

MATTER COARSE EMISSIONS FOR JARB1 2002 AND 2018 WORST DAYS

4.5 VISIBILITY AND SOURCE APPORTIONMENT MODELING SUMMARY 

Results of the CMAQ visibility modeling forecasts indicate the Jarbidge WA will meet the URP 

for 2018 for the worst days with no degradation of best days. 

Results of the PSAT source apportionment modeling identify the source areas contributing to 

sulfate and nitrate extinction at the JARB1 monitor. Table 4-5 lists the four source areas with the 

highest contribution of SO2 and NOx to JARB1 based on the source apportionment modeling. 

The area with the greatest sulfate contribution is Outside Domain (or boundary conditions), 

which has contributions four times greater than any other source area. Point, area and natural 

fire sources all contribute approximately one-third to visibility impairment at the Jarbidge WA. 

Nevada is not a significant contributor of sulfate at the Jarbidge WA. 

Idaho, closely followed by Outside Domain, is the largest source area contributor to nitrate at 

JARB1. Nevada and Utah also contribute significantly to modeled nitrate concentrations in the 

Jarbidge WA. Point, mobile and area sources contribute subequally to nitrate, with a lesser 

contribution from natural fire sources. 

Boundary conditions represent the background concentrations of pollutants that enter the edge of 

the modeling domain. Emissions can be transported great distances and represent international 

emissions beyond the portions of Canada and Mexico that lie within the modeling domain. 

Boundary conditions represent emissions from sources beyond the jurisdiction of United States 

regulatory agencies and are uncontrollable for the purposes of Nevada’s regional haze SIP. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-30 
TABLE 4-5

SUMMARY OF 2018 MODEL RESULTS FOR JARBIDGE WILDERNESS AREA

Sources* 1st 2nd 3rd 4th Sources* 1st 2nd 3rd 4th

Outside

Domain Idaho Oregon

Pacific

Offshore Idaho

Outside

Domain Nevada Utah

43.8% 10.3% 7.2% 6.9% 30.3% 27.5% 13.1% 10.6%

* Outside Domain not included in pie charts

Point Sources

Mobile Sources

Natural Fire Sources

Area Sources

2018 Sulfate PSAT - 20% Worst Days

4 Regions with Greatest Contribution to Jarbidge

2018 Nitrate PSAT - 20% Worst Days

4 Regions with Greatest Contribution to Jarbidge

Table 4-6 lists the 2002 to 2018 change in modeled particulate sulfate and nitrate concentrations 

at the Jarbidge WA for the worst days. The 2018 PSAT modeling forecasts overall decreases in 

total sulfate and nitrate concentrations (i.e., “Total SO4” and “Total NO3” columns of Table 4-6) 

at the JARB1 monitor. However, the modeled contributions to sulfate at JARB1 due to Nevada 

sources (NV SO4 column) increased by 14 percent, while modeled nitrate contributions due to 

Nevada sources (NV NO3 column) decreased by 12 percent. The PSAT modeling used the 

Plan02c and Base18b emission inventories, as discussed in Chapter One. 

TABLE 4-6

CHANGE IN WORST DAYS MODELED CONCENTRATIONS 

OF SULFATE AND NITRATE

Class I

Area Year

Total

SO4 

(ug/m

3

)

NV SO4 

(ug/m

3

)

NV

Share 

SO4

NV 

[SO4] 

Change

Total 

NO3 

(ug/m

3

)

NV NO3 

(ug/m

3

)

NV 

Share

NO3

NV 

[NO3] 

Change

2002 0.529 0.0241 4.6% 0.308 0.0358 11.6%

2018 0.507 0.0275 5.4% +14% 0.240 0.0314 13.1% -12%

Jarbidge

Wilderness

Area

Figure 4-35 summarizes the Nevada Plan02c and Base18b SO2 inventories, while Figure 4-36 

summarizes the Nevada Plan02d and PRP18a SO2 inventories. Figures 4-37 and 4-38 

summarize the same data for NOx. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-31 
FIGURE 4-35 

NEVADA SO2 PLAN02c AND BASE18b 

EMISSION INVENTORY COMPARISON

FIGURE 4-36 

NEVADA SO2 PLAN02d AND PRP18a 

EMISSION INVENTORY COMPARISON

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-32 
FIGURE 4-37 

NEVADA NOx PLAN02c AND BASE18b 

EMISSION INVENTORY COMPARISON

FIGURE 4-38 

NEVADA NOx PLAN02d AND PRP18a 

EMISSION INVENTORY COMPARISON

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-33 
The projected 2018 emissions inventories for both SO2 and NOx show substantial overall 

reductions from the 2002 baseline inventories. However, the PRP18a SO2 projected inventory 

does not show as great reductions from 2002 for point sources as the Base18b and less total SO2

reductions. For NOx emissions, the total projected reductions are very similar, with a slight 

reduction in the PRP18a point source projection. 

Comparison of the Plan02d and PRP18a emission inventories shows Nevada’s total SO2

emissions decreased by 33 percent from the baseline period to 2018, while SO2 point source 

emissions decreased by 44 percent (see Table 3-7). Similarly, Nevada’s total NOx emissions 

decreased by 17 percent from the baseline to 2018, while NOx point source emissions increased 

by 13 percent (see Table 3-8). 

The projected overall particulate sulfate and nitrate concentration reductions at JARB1, shown 

on Table 4-6, are due to Nevada’s and regional reductions of SO2 and NOx emissions. Organic 

aerosol PSAT results identify primary and secondary biogenic organic aerosol emissions as the 

dominant contributor to projected OC concentrations at JARB1 for 2018. These results also 

indicate primary organic aerosol emissions due to wildland fire are seasonally significant. 

Regional WEP analyses appear to confirm the important contributions of projected sulfate and 

nitrate emissions from point sources in Idaho and Nevada, as well as the influence of nitrate 

emission from mobile sources in the states adjacent to Nevada to visibility impairment at JARB1

in 2018. These analyses also indicate the significant contributions of natural sources due to 

natural fire emissions of OC and EC and windblown dust emissions of PMF and PMC to 

visibility impairment at JARB1. 

The results of the projected 2018 visibility and source apportionment modeling indicate the RPG 

for the Jarbidge WA will exceed the URP and identifies Nevada point sources of SO2, as well as 

point and mobile sources of NOx, as source area candidates for consideration of additional 

control measures during future regional haze planning periods. 

NEVADA REGIONAL HAZE STATE IMPLEMENTATION PLAN, October 2009 4-34