Redesignation Request and Maintenance 

Plan for Particulate Matter (PM10)

Clark County, Nevada

August 2012
Request for Redesignation and Maintenance Plan for Particulate Matter (PM10)

August 2012 ii

APPROVED BY THE CLARK COUNTY BOARD OF COMMISSIONERS

Susan Brager, Chair

Steve Sisolak, Vice-Chair

Larry Brown

Tom Collins

Chris Giunchigliani

Mary Beth Scow

Lawrence Weekly

PREPARED BY

Clark County Department of Air Quality 

Planning Division
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EXECUTIVE SUMMARY

This Request for Redesignation and Maintenance Plan for Particulate Matter (PM10) is a formal 

request by Clark County, through its Department of Air Quality, to the U.S. Environmental 

Protection Agency (EPA) to redesignate the Clark County PM10 nonattainment area to attainment 

for the 1987 24-hour National Ambient Air Quality Standard (NAAQS). The plan summarizes 

the progress in attaining the PM10 standard, demonstrates that all Clean Air Act and Clean Air 

Act Amendment requirements for attainment have been met, and presents a plan to assure 

continued maintenance over the next 10 years.

In 1990, EPA designated the Las Vegas Valley, Hydrographic Area 212 (HA 212) in Clark 

County, as being in “moderate” nonattainment of the 24-hour PM10 NAAQS. In 1993, EPA 

reclassified HA 212 as a “serious” nonattainment area because Clark County could not 

demonstrate attainment by the required date of December 1994. 

In June 2001, Clark County submitted a PM10 State Implementation Plan (SIP) that met federal 

requirements for serious PM10 nonattainment areas. The SIP demonstrated that the adoption and 

implementation of Best Available Control Measures for fugitive sources and continuation of 

controls for stationary sources would result in attainment of the 24-hour NAAQS by December 

31, 2006. Although the Act required the SIP demonstrate attainment of the PM10 NAAQS no 

later than December 31, 2001, EPA granted Clark County a five-year extension for the 24-hour 

attainment date. Final EPA approval of the Clark County PM10 SIP became effective in July 

2004. 

In June 2007, Clark County submitted the PM10 Milestone Achievement Report, prepared in 

accordance with 40 CFR Part 52. The report documents Clark County’s attainment of the 24-

hour PM10 NAAQS by the applicable date of December 31, 2006. In August 2010, EPA 

published a determination of attainment for PM10 for the Las Vegas Valley in the Federal 

Register.

Following on that success, this maintenance plan provides a PM10 attainment demonstration that 

uses the most recently adopted planning variables, including those approved by the Regional 

Transportation Commission of Southern Nevada, which is the designated Metropolitan Planning 

Organization for the Las Vegas urban area. The plan also provides revised emission inventories 

and motor vehicle emissions budgets.

After EPA approval, this plan will become federally enforceable and will determine how Clark 

County will maintain the 1987 PM10 NAAQS through 2023. Once approved, the budgets in this

plan will be the projected budgets used to determine transportation conformity in future regional 

transportation plans.
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TABLE OF CONTENTS

1.0 INTRODUCTION..............................................................................................................1

1.1 Introduction..............................................................................................................1

1.2 Characteristics and Health Effects...........................................................................1

1.3 National Ambient Air Quality Standards.................................................................2

1.4 History of Clark County Nonattainment Area .........................................................2

1.4.1 Nonattainment Area .....................................................................................3

1.5 Required Components of a Redesignation Request.................................................6

1.5.1 Attainment of the PM10 Standards...............................................................6

1.5.2 Approved Implementation Plan ...................................................................6

1.5.3 Permanent and Enforceable Improvements in Air Quality..........................6

1.5.4 Requirements under Section 110 and Part D of the Clean Air Act .............6

1.5.5 Approvable Maintenance Plan: Section 175(a) of the Clean Air Act..........6

2.0 ATTAINMENT OF THE PM10 STANDARD.................................................................1

2.1 Introduction..............................................................................................................1

2.2 Monitoring Network ................................................................................................1

2.3 Design value.............................................................................................................3

2.4 Monitoring Results and Attainment Demonstration................................................5

2.5 Quality Assurance Program.....................................................................................5

3.0 STATE IMPLEMENTATION PLAN APPROVAL......................................................1

3.1 Introduction..............................................................................................................1

3.2 Previous Plan Approvals..........................................................................................1

4.0 PERMANENT AND ENFORCEABLE IMPROVEMENT IN AIR QUALITY........1

4.1 Introduction..............................................................................................................1

4.2 Economic Conditions...............................................................................................1

4.2.1 Population Trends........................................................................................1

4.2.2 Development Patterns..................................................................................2

4.3 Meteorological Conditions.......................................................................................2

4.4 Attainment and Maintenance Control Measures......................................................5

4.4.1 Stationary Point and Nonpoint Source Regulations.....................................5

4.5 Additional Emission Reduction Control Measures..................................................6

4.5.1 Regional Haze Rule .....................................................................................6

4.5.2 Transportation Conformity ..........................................................................6

4.5.3 Clark County Natural Events Action Plan...................................................6

4.6 Air Quality Trend Analysis: Weight of Evidence....................................................7

5.0 REQUIREMENTS FROM SECTION 110 AND PART D OF THE CLEAN AIR 

ACT AMENDMENTS.......................................................................................................1

5.1 Introduction..............................................................................................................1

5.2 Section 110 Requirements.......................................................................................1

5.2.1 Section 110(a)(2) .........................................................................................1

5.2.2 Section 110(l)...............................................................................................2
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5.3 Part D Requirements................................................................................................2

5.3.1 Section 172(c)..............................................................................................2

5.3.2 Section 176(c)..............................................................................................2

6.0 MAINTENANCE PLAN...................................................................................................3

6.1 Introduction..............................................................................................................3

6.1.1 Inventory Domain ........................................................................................3

6.2 Transportation Input Data ........................................................................................3

6.3 Efficiency and Effectiveness Factors.......................................................................3

6.4 Emission Inventory Type Categories.......................................................................3

6.4.1 Point Sources ...............................................................................................3

6.4.2 Nonpoint Sources.........................................................................................4

6.4.3 Mobile Sources ............................................................................................4

6.4.4 Banked Emission Reduction Credits ...........................................................5

6.5 Summary of Emission Inventories...........................................................................5

6.6 Maintenance Demonstration ....................................................................................8

6.7 Rollback Model........................................................................................................9

6.8 Monitoring Network and Verification of Continued Attainment ..........................11

6.9 Contingency Measures...........................................................................................11

6.9.1 Potential Contingency Measures................................................................11

6.9.2 Tracking and Triggering Mechanisms.......................................................12

6.9.3 Action Resulting from Trigger Activation.................................................13

6.10 Subsequent Maintenance Plan Revisions...............................................................13

7.0 MOTOR VEHICLE EMISSIONS BUDGETS ...............................................................1

8.0 REFERENCES...................................................................................................................1

APPENDICES

APPENDIX A: Technical Support Document .......................................................................... A-1

APPENDIX B: Documentation of the Public Review Process..................................................B-1
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LIST OF FIGURES

Figure 1-1. Clark County PM10 Nonattainment Area (HA 212)....................................................4

Figure 1-2. BLM Disposal Area within HA 212. ..........................................................................5

Figure 2-1. Clark County PM10 Monitoring Stations. ...................................................................2

Figure 2-2. Design Values for 1999–2010 (μg/m3).......................................................................4

Figure 4-1. Wind Speeds (2001–2010)..........................................................................................4

Figure 4-2. Precipitation (2001–2010). .........................................................................................4

Figure 4-3. Actual and Log PM10 Trend........................................................................................8

Figure 6-1. Emission Distribution in 2008. ...................................................................................7

Figure 6-2. Emission Distribution in 2023. ...................................................................................7

Figure 6-3. Nonpoint Emissions in the BLM Disposal Area.........................................................8

Figure 6-4. Comparison of 2008, 2015, and 2023 PM10 Emissions..............................................9

LIST OF TABLES

Table 2-1. Clark County PM10 Monitoring Sites .........................................................................1

Table 2-2. Estimation of PM10 Design Concentrations................................................................3

Table 2-3. Design Values for 2008–2010 (μg/m3

).......................................................................3

Table 2-4. Summary of Las Vegas Valley PM10 Monitoring Data, 2008-2010...........................5

Table 4-1. Clark County Population History (1990-2010)...........................................................1

Table 4-2. Monthly Averages for Temperature and Rainfall (1937 to 2010)..............................3

Table 6-1. Daily VMT Data Used to Develop Emission Inventories ..........................................3

Table 6-2. Summary of Total Daily PM10 Emissions (tpd)..........................................................6

Table 7-1. BLM Disposal Area PM10 Mobile Source Emissions (tpd)........................................1

Table 7-2. Revised Maintenance Demonstration .........................................................................3

Table 7-3. PM10 MVEBs for the BLM Disposal Area (tpd).........................................................3
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ACRONYMS AND ABBREVIATIONS

Acronyms

AQR Clark County Air Quality Regulation

AQS Air Quality System 

BACM Best Available Control Measures

BCC Clark County Board of County Commissioners

BLM Bureau of Land Management

BMP best management practices

CAA Clean Air Act

CFR Code of Federal Regulations

EI emission inventory

EPA U.S. Environmental Protection Agency

ERC emission reduction credit

FR Federal Register

HA Hydrographic Area

MVEB motor vehicle emission budget

NAAQS National Ambient Air Quality Standards

NDEP Nevada Division of Environmental Protection

NEAP Natural Events Action Plan

NRS Nevada Revised Statues

RTC Regional Transportation Commission of Southern Nevada 

SIP state implementation plan

VMT vehicle miles traveled

Abbreviations

mph miles per hour

PM2.5 particulate matter less than 2.5 microns in mean aerodynamic diameter

PM10 particulate matter less than 10 microns in mean aerodynamic diameter

tpd tons per day

μg/m3 micrograms per cubic meter

μm microns
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1.0 INTRODUCTION

1.1 INTRODUCTION

Clark County, in coordination with the Nevada Division of Environmental Protection (NDEP), 

requests that the U.S. Environmental Protection Agency (EPA) redesignate the Clark County 

nonattainment area, Hydrographic Area (HA) 212, to attainment status for particulate matter less 

than 10 microns (μm) in diameter (PM10) under the 1987 PM10 24-hour National Ambient Air 

Quality Standard (NAAQS). 

To complete this redesignation request and maintenance plan in accordance with EPA guidance, 

Clark County inventoried emissions of PM10 for the baseline year (2008) and projected those 

emissions outward to 2015 and 2023. The inventories were adjusted to reflect federal, state, and 

local rules on PM10 emissions that have already been adopted or implemented. These controls 

were shown to reduce overall PM10 emissions through the maintenance year (2023).

1.2 CHARACTERISTICS AND HEALTH EFFECTS 

“Particulate matter” is a general term used to describe a complex group of airborne solid, liquid, 

and semi volatile materials of various sizes and compositions. Primary PM is emitted directly 

into the atmosphere from anthropogenic activities, such as agricultural operations, industrial 

processes, construction and demolition activities, and entrainment of road dust into the air, and 

nonanthropogenic activities, such as windblown dust and ash from forest fires. Secondary PM is 

formed in the atmosphere from (predominantly gaseous) combustion by-product precursors, such 

as nitrogen oxides and volatile organic compounds. The overwhelming majority of airborne PM 

in Clark County is primary PM; the major source is fugitive windblown dust, with contributions 

from entrained road dust and construction activities. 

Particulate size is a critical characteristic of PM that primarily determines the location of its 

deposition along the respiratory system. EPA has established two types of PM air quality 

standards, one for PM10 and one for PM2.5. (The latter refers to the subset of PM10 with an 

aerodynamic diameter smaller than 2.5 μm.)

PM10 has a detrimental effect on human health because it can accumulate in the respiratory 

system. Short-term exposure can irritate the lungs and may cause immune system responses, 

resulting in lung constriction that produces shortness of breath and coughing. Larger particles 

deposit in the upper respiratory tract; smaller particles travel deep into the lungs and are retained 

longer.

Long-term, low-level PM10 exposure may cause cancer and premature death. Those with a 

history of asthma or chronic lung disease are especially sensitive to these effects. The elderly or 

those with heart conditions may also have severe reactions, since the resulting lack of oxygen 

may strain the heart.
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1.3 NATIONAL AMBIENT AIR QUALITY STANDARDS 

On July 1, 1987, EPA revised the PM NAAQS (Volume 52, page 34634 of the Federal Register

(52 FR 24634)). The previous standards addressed total suspended particulates, without regard to 

size; the revised standards addressed only particles having an aerodynamic diameter of 10 μm or 

less. EPA determined that these microscopic particles can be inhaled deep into the lungs and 

present a hazard to public health when concentrations exceed certain levels. Both annualaveraged and 24-hour averaged PM10 standards were promulgated; however, EPA revoked the 

annual-averaged standard in 2006 (71 FR 61144). The current PM10 (primary) standard retains 

only the 24-hour averaging time, at a level of 150 micrograms per cubic meter (μg/m3).

1.4 HISTORY OF CLARK COUNTY NONATTAINMENT AREA

After passage of the 1990 Clean Air Act Amendments, EPA designated all areas previously 

classified as Group I areas as “moderate” nonattainment areas, including HA 212 (CAA 

§107(d)(4)(B)). EPA required these moderate nonattainment areas to submit a state 

implementation plan (SIP) by November 1991 that would demonstrate attainment of the PM10

NAAQS by December 1994. Because of unprecedented growth, high-wind events, and other 

factors, Clark County could not demonstrate attainment by the required date, and EPA 

reclassified HA 212 as a “serious” nonattainment area on January 8, 1993 (58 FR 3334). In 1997, 

a PM10 SIP revision was submitted. In December 2000, the Clark County Board of County 

Commissioners (BCC) requested that the state formally withdraw all previously submitted SIPs 

and addenda because none demonstrated attainment of the NAAQS. 

Section 110 of the Clean Air Act (CAA) requires that states not meeting the NAAQS submit a 

SIP detailing programs to bring the nonattainment area into attainment. After completing 

comprehensive research and work programs to address the problems identified in the 1997 PM10

SIP revision, Clark County submitted a new SIP to EPA in June 2001 that met federal 

requirements for remediating serious PM10 nonattainment areas. This new SIP demonstrated that 

the adoption and implementation of Best Available Control Measures (BACM) for fugitive 

sources and continuation of controls for stationary sources would result in attainment of the 

annual average PM10 NAAQS by 2001 and attainment of the 24-hour NAAQS by December 31, 

2006. Although the CAA required the SIP demonstrate attainment of the PM10 NAAQS no later 

than December 31, 2001, EPA granted Clark County a five-year extension for the 24-hour 

attainment date. Clark County supported its extension request with a Most Stringent Measure 

control analysis that showed the emission control programs proposed for the valley were at least 

as stringent, if not more so, than control programs implemented in other nonattainment areas.

In June 2004, EPA published final approval of the PM10 SIP (69 FR 32273). In June 2007, Clark 

County submitted a milestone achievement report that described the county’s progress in 

implementing the SIP (DAQEM 2007a). In August 2010, EPA determined HA 212 had attained 

the PM10 NAAQS (75 FR 45485). 

With submittal of this redesignation request and maintenance plan, Clark County is requesting 

that EPA designate Clark County in attainment of the PM10 NAAQS.
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1.4.1 Nonattainment Area

Figure 1-1 depicts the PM10 nonattainment area established by EPA (HA 212), which is roughly 

1,500 square miles, largely under federal control, and includes the:

• City of Las Vegas

• City of North Las Vegas

• City of Henderson

• Unincorporated urban areas of Clark County

• Desert National Wildlife Refuge lands

• Humboldt-Toiyabe National Forest lands

• Red Rock Canyon National Conservation Area

• Nellis Air Force Base

• Nellis Bombing and Gunnery Range

• Nellis Small Arms Range

• Clark County Shooting Range

• Las Vegas Paiute Indian Reservation

• Spring Mountain State Park

• Lake Mead National Recreational Area.

More than 80 percent of the land in Nevada is under federal jurisdiction, most of it managed by

the Bureau of Land Management (BLM). In 1998, Congress passed the Southern Nevada Public 

Land Management Act, which allowed BLM to sell, trade, or lease public land within a specific 

area around Las Vegas. There was an amendment to this boundary in 2003, and minor 

adjustments thereafter. The area currently comprises 327,047 acres and is known as the BLM 

disposal area (Figure 1-2). Lands controlled by the federal government outside this area remain 

in a native or managed state, and the disposal boundary can only be changed by an act of 

Congress.

Because the BLM disposal area contains nearly all of the anthropogenic sources and sensitive 

receptors within the nonattainment area, it was used for the attainment demonstration in the 

EPA-approved PM10 SIP and in this maintenance plan. 
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Figure 1-1. Clark County PM10 Nonattainment Area (HA 212).
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Figure 1-2. BLM Disposal Area within HA 212.

ND Non Disposable 

Area
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1.5 REQUIRED COMPONENTS OF A REDESIGNATION REQUEST

CAA Section 107(d)(3)(E) defines the five conditions that must be met before EPA can 

redesignate a nonattainment area to attainment. With the submittal of this plan, Clark County 

meets these five conditions.

1.5.1 Attainment of the PM10 Standards

Clark County must show that the area is attaining the applicable NAAQS. Redesignation of PM10

nonattainment areas to attainment are based solely on ambient air quality data. Section 2 presents 

the data used to demonstrate attainment.

1.5.2 Approved Implementation Plan

The SIP for the nonattainment area must be fully approved under CAA Section 110(k) and must 

satisfy all requirements that apply to the nonattainment area. Section 3 provides the information 

required by CAA Section 110(k) to show that Clark County has an approved PM10 SIP.

1.5.3 Permanent and Enforceable Improvements in Air Quality

Clark County must be able to reasonably attribute improvements in air quality to emission 

reductions that are permanent and federally enforceable. Section 4 shows that improved air 

quality in the Clark County area is the result of permanent and enforceable emission reduction 

control measures, as opposed to air quality improvements resulting from adverse economic or 

meteorological conditions. 

1.5.4 Requirements under Section 110 and Part D of the Clean Air Act

Clark County must meet all requirements of Section 110 and Part D that applied before submittal 

of the redesignation request. Section 5 discusses the noninterference of this SIP with any 

applicable requirements concerning attainment, and with reasonable further progress towards 

attainment of all other criteria pollutant NAAQS or any other applicable CAA requirement. 

1.5.5 Approvable Maintenance Plan: Section 175(a) of the Clean Air Act 

Section 107(d)(3)(E) of the Clean Air Act Amendments stipulates that EPA must fully approve a 

maintenance plan that meets the requirements of CAA Section 175(a) before it can redesignate 

an area to attainment. Section 6 provides a plan to maintain the PM10 NAAQS for at least 10 

years after redesignation. 
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2.0 ATTAINMENT OF THE PM10 STANDARD

2.1 INTRODUCTION

The first required component of an area’s redesignation request is a demonstration that it has 

attained the NAAQS. This attainment demonstration is based on quality-assured monitoring data 

representative of the Clark County PM10 nonattainment area. A total of three consecutive years 

of non-violating air quality data is needed to show attainment of the standard. A complete year of 

air quality data comprises all four calendar quarters, with each quarter containing data from at 

least 75 percent of the scheduled sampling days.

Attainment of the PM10 standard is demonstrated through establishment of a design value. As 

specified in Appendix K of Title 40, Part 50 of the Code of Federal Regulations (40 CFR 50), 

attainment of the 24-hour standard is determined by calculating the expected number of 

exceedances of the 150 μg/m3 limit per year: the standard is attained when the expected number 

of exceedances is one or less. 

On August 3, 2010, EPA issued a final rule determining that the PM10 NAAQS had been 

attained for the HA 212 nonattainment area by the applicable attainment date of December 31, 

2006, and that the area was currently attaining the standard (75 FR 45485). Therefore, the 

requirements of CAA Section 107(d)(3)(E)(i) have been satisfied. 

2.2 MONITORING NETWORK 

40 CFR 58 defines the requirements for the ambient air quality monitoring programs mandated 

by the CAA. Clark County’s PM10 monitoring network consists of eight State and Local Air

Monitoring System monitors; the system is governed by quality assurance and quality control 

procedures and subject to periodic EPA performance audits. As shown in Table 2-1, the 

monitoring objective of all but one station is “population exposure.” The exception is the Jean

monitoring station, which monitors background concentrations. 

Table 2-1. Clark County PM10 Monitoring Sites

Site Name Scale Monitoring Objective

Paul Meyer Middle Population exposure

Palo Verde Neighborhood Population exposure

Joe Neal Neighborhood Population exposure

Green Valley Middle Population exposure

Sunrise Acres Neighborhood Population exposure

Jean Regional Background

J.D. Smith Neighborhood Population exposure

Boulder City Neighborhood Population exposure

Figure 2-1 shows the locations of the Clark County PM10 monitoring stations. Table 2-2 shows

the design value concentrations measured at these stations from 2008–2010. 
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Figure 2-1. Clark County PM10 Monitoring Stations.
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Table 2-2. Design Values for 2008–2010 (μg/m3)

Site ID Site Name

Number of 

Daily Values

1st 

High

2nd 

High

3rd 

High

4th 

High

Site

Value

Design Value

(highest site value)

0020 E. Craig Road 876 123 102 98 96 98

98

0043 Paul Meyer 1,050 83 76 70 66 66

0072 Lone Mountain 806 70 69 59 58 59

0073 Palo Verde 1,060 57 54 52 51 51

0075 Joe Neal 1,047 120 96 95 84 84

0298 Green Valley 1,041 144 81 80 78 80

0561 Sunrise Acres 1,047 106 103 86 81 81

1021 Orr 804 85 75 71 70 71

2002 J.D. Smith 1,045 109 91 82 78 78

2.3 DESIGN VALUE

The design value (in μg/m3) is the concentration derived from a statistical approach to 

monitoring data that describes the air quality status of a given area, during a specific period,

relative to the NAAQS. When a design value is related to a comprehensive emissions inventory 

(EI) for the same period, future concentrations can be predicted through emissions forecasts.

The 24-hour PM10 baseline year (2008) design value for the BLM disposal area was derived 

using the PM10 SIP Development Guideline (EPA 1987). Data from the nine PM10 monitoring 

sites that operated from 2008–2010 were ranked by the four highest values for each site during 

that period. As Table 2-3 shows, the first, second, third, or fourth highest values are selected for 

each site, depending on the number of recorded values at that site during the three-year period.

Table 2-3. Estimation of PM10 Design Concentrations

The data analysis identified two exceptional events, one on February 13, 2008, and another on 

May 21, 2008. On these days, HA 212 experienced high-wind events during which the 24-hour 

PM10 standard was violated.

Sustained winds of 25 miles per hour (mph) and gusts of 40 mph are the established thresholds 

for exceptional high-wind events in HA 212; winds greater than these values overwhelm BACM.

Wind speeds during both identified events were greater than these thresholds. Since PM10

emissions were not reasonably controllable during these events, they were not reasonably 

Number of Daily Values Data Point Used for Design Concentration

≤ 347 Highest Value

348 – 695 Second Highest Value

696 – 1,042 Third Highest Value

1,043 – 1,096 Fourth Highest Value
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preventable; the events were therefore flagged in EPA’s Air Quality System (AQS). In 

accordance with EPA’s Exceptional Event Rule, Clark County is requesting that these

exceedance days be excluded from regulatory consideration.

The two event days were not considered in the design value calculations. Clark County ranked 

the remaining high values from each site for the three-year period (Table 2-2). The highest value 

from the list, 98 μg/m3, was determined to be the design value. The design day (i.e., the day on 

which the design value concentration occurred) was determined to be April 15, 2008.

Figure 2-2 shows the 12-year trend of the design values in HA 212. The data demonstrate a 

significant improvement in air quality since implementation of the PM10 SIP.

Figure 2-2. Design Values for 1999–2010 (μg/m3

).
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2.4 MONITORING RESULTS AND ATTAINMENT DEMONSTRATION

The monitoring data illustrated by Figure 2-2 verify that the Clark County nonattainment area

has been in attainment with the PM10 NAAQS since 2006, in accordance with the requirements 

of 40 CFR 58. Table 2-4 outlines the highest 24-hour concentrations during 2008–10, excluding 

the two high-wind events of February 13, 2008, and May 21, 2008. 

Table 2-2. Summary of Las Vegas Valley PM10 Monitoring Data, 2008–2010

Site ID Monitoring Site

Highest 24-hour PM10 Concentration

(μg/m3)

Expected Exceedances Per 

Year

2008 2009 2010 2008-2010

0020 E. Craig Road 123 67 N/A1 0

0043 Paul Meyer 76 83 48 0

0072 Lone Mountain 70 69 N/A1 0

0073 Palo Verde 54 57 49 0

0075 Joe Neal 120 95 64 0

0298 Green Valley 144 81 52 0

0561 Sunrise Acres 106 85 57 0

1021 Orr 71 85 N/A1 0

2002 J. D. Smith 109 77 62 0

1 Site is no longer in operation or no longer monitoring PM10.

Since none of the values are greater than the PM10 NAAQS, the expected number of exceedances 

in the Las Vegas Valley for 2008–2010 is zero. This is lower than the annual expected 

exceedance rate for the 24-hour PM10 NAAQS, demonstrating continued attainment of the 

standard.

2.5 QUALITY ASSURANCE PROGRAM

PM10 data have been collected and verified in accordance with 40 CFR 58 and the Quality 

Control & Assurance System for Continuous Particulate Matter (2.5 & 10) Pollutants (Quality 

Assurance Project Plan) (DAQEM 2008). PM10 audit data are submitted to AQS, and the audit 

schedule is available in the annual network plan Clark County submits to EPA. 
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August 2012 1

3.0 STATE IMPLEMENTATION PLAN APPROVAL

3.1 INTRODUCTION

The second required component of an area’s redesignation request is a fully approved SIP 

satisfying all requirements that apply to the nonattainment area under CAA Section 110(k), 

which addresses completeness findings, deadlines for EPA actions, types of EPA actions, and 

sanctions that may be applied to areas failing to meet CAA requirements. The information in this 

section demonstrates, as required under CAA Section 110(k), that there is an approved SIP for 

the Clark County PM10 nonattainment area.

3.2 PREVIOUS PLAN APPROVALS

In June 2001, Clark County submitted a PM10 SIP that met federal requirements for remediating 

serious PM10 nonattainment areas. This SIP demonstrated that the adoption and implementation 

of best available control measures and technologies would result in attainment of the 24-hour 

NAAQS by December 31, 2006. Final EPA approval of the Clark County PM10 SIP was effective 

in July 2004 (69 FR 32273).
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August 2012 1

4.0 PERMANENT AND ENFORCEABLE IMPROVEMENT 

IN AIR QUALITY

4.1 INTRODUCTION

The third required component of a redesignation request is a demonstration that improvements in 

air quality are reasonably attributed to emission reductions that are permanent and federally 

enforceable. The information in this section shows that improved air quality in the Clark County 

PM10 nonattainment area is the result of permanent and enforceable emission reduction control 

measures, as opposed to adverse economic or meteorological conditions. 

4.2 ECONOMIC CONDITIONS

Clark County, formed in 1909 and located at the southern tip of Nevada, is an area of more than 

8,000 square miles. Most county residents live within the BLM disposal area, a 511-square-mile

basin inside HA 212. The BLM disposal area was one of the fastest-growing areas in the nation 

for several decades, and hosts up to 40 million visitors each year. Rapid population growth, high 

construction activity, disturbance of vacant lands, and high-wind events led to increased PM10 

24-hour NAAQS exceedances in the 1990s and early 2000s.

4.2.1 Population Trends

More than 96 percent of Clark County’s population resides in HA 212, and more than 99 percent 

of the population in HA 212 resides within the BLM disposal area. Table 4-1 provides 

population data for Clark County over the last 20 years; during that time, the average annual 

population growth was 4.8 percent. 

Table 4-1. Clark County Population History (1990-2010)

Year Clark County HA 212 BLM Disposal 

Area

Annual Population 

Change in HA 212

Annual Percent Increase

1990 805,519 776,180 773,029 — —

1991 829,839 797,973 794,779 21,793 2.8%

1992 870,692 837,862 834,604 39,889 5.0%

1993 919,388 884,184 880,874 46,322 5.5%

1994 986,152 949,139 945,784 64,955 7.3%

1995 1,048,668 1,009,812 1,006,467 60,673 6.4%

1996 1,119,708 1,077,971 1,074,597 68,159 6.7%

1997 1,170,113 1,127,419 1,124,161 49,448 4.6%

1998 1,246,193 1,199,347 1,196,164 71,928 6.4%

1999 1,321,176 1,272,638 1,269,290 73,291 6.1%

2000 1,428,689 1,372,022 1,367,181 99,384 7.8%

2001 1,498,278 1,448,827 1,445,970 76,805 5.6%

2002 1,578,332 1,525,226 1,522,291 76,399 5.3%

2003 1,641,529 1,586,032 1,583,363 60,806 4.0%

2004 1,747,025 1,691,647 1,685,391 105,615 6.7%

2005 1,815,700 1,759,636 1,752,457 67,989 4.0%
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Year Clark County HA 212 BLM Disposal 

Area

Annual Population 

Change in HA 212

Annual Percent Increase

2006 1,912,654 1,855,019 1,847,643 95,383 5.4%

2007 1,996,542 1,933,602 1,925,411 78,583 4.2%

2008 1,986,145 1,924,817 1,916,585 -8,785 -0.5%

2009 2,006,347 1,943,812 1,936,450 18,995 1.0%

2010 2,036,358 1,974,611 1,966,074 30,798 1.6%

Source: Clark County Department of Comprehensive Planning.

4.2.2 Development Patterns

More than 90 percent of the land of HA 212 is owned by federal agencies. The land is managed 

with varying types and intensities of use, according to individual agencies’ land and resource 

management plans. BLM has the largest holding, including the Red Rock National Conservation 

Area west of Las Vegas. Most of the Spring Mountain Range, including Mt. Charleston, is 

administered by the U.S. Forest Service as part of the Humboldt-Toiyabe National Forest. The 

rapid disturbance and development of vacant land has been concentrated in the BLM disposal 

area, which includes the cities of Las Vegas, Henderson, and North Las Vegas, as well as the 

unincorporated areas of Clark County.

Monitored levels of PM10 have shown a continued decline since the early 2000s despite the rapid 

growth. It is reasonable, therefore, to conclude that improvements in HA 212 PM10 air quality 

have not been caused by a downturn in economic conditions, i.e., any reduction of PM10

concentrations in HA 212 can be reasonably attributed to the emission reduction control 

measures in the PM10 SIP, which are permanent and federally enforceable.

4.3 METEOROLOGICAL CONDITIONS

Summers in Clark County display the classic characteristics of the desert Southwest: daily high 

temperatures in the lower elevations often exceed 100oF, with lows above 70oF. The summer 

heat is usually tempered by low relative humidity, which may increase for several weeks during 

July and August in association with moist monsoonal wind flows from the south. This is the 

most common period for thunderstorms in the valley, which can result in high-wind events. 

Temperatures during the spring and fall are generally moderate, with strong winds being the 

most persistent weather hazard.

Winters are generally mild and pleasant. Afternoon temperatures average 60oF, and the sky is 

normally clear and sunny. Snow accumulation on valley floors is rare; however, higher 

elevations, such as the Spring Mountains, typically receive 5–10 feet of snowfall annually. Based 

on measurements from McCarran International Airport over the past 30 years, temperatures fall 

below 32oF an average of 24 days a year. 

Average annual rainfall in the valley, also measured at McCarran, is approximately 4.16 inches. 

Table 4-2 lists temperature and rainfall averages in Clark County over the last seven decades.
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Table 4-2. Monthly Averages for Temperature and Rainfall (1937 to 2010)

Month Maximum (°F) Minimum (°F) Average (°F) Rainfall (inches)

January 57.1 34.5 47.0 0.52

February 62.5 38.9 52.2 0.58

March 69.5 44.3 58.3 0.45

April 78.2 51.7 66.0 0.20

May 88.5 61.1 75.4 0.15

June 98.6 69.9 85.6 0.07

July 104.6 76.5 91.2 0.43

August 102.2 74.8 89.3 0.44

September 94.7 66.6 81.3 0.32

October 81.3 54.3 68.7 0.25

November 66.5 42.0 55.0 0.36

December 57.2 34.7 47.0 0.40

Annual Average 80.1 54.1 68.1 4.16

Source: DRI (2010). 

Elevated levels of PM10 emissions in HA 212 are largely associated with wind-blown dust, reentrained road dust, or construction emissions, and are often amplified by dry, arid conditions. 

High-wind events in HA 212 generally occur between February–May and September–December,

although high winds have been recorded in other months as storms pass through. The monitoring 

stations that record the highest concentrations of PM10 during high-wind events are typically 

those located near large expanses of disturbed soil.

Figures 4-1 and 4-2 illustrate data on wind speed and precipitation, respectively, in HA 212 for 

the last 10 years. Rainfall dropped significantly during this time (2006–2009), although winds 

remained relatively constant. SIP-implemented PM10 control measures were effective in spite of 

drought-like conditions, so it is reasonable to assume that lower PM10 concentrations over the 

last 10 years were not caused by atypical meteorological conditions.
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Figure 4-1. Wind Speeds (2001–2010).

Figure 4-2. Precipitation (2001–2010).
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4.4 ATTAINMENT AND MAINTENANCE CONTROL MEASURES

CAA Section 110(a)(2)(A) requires that each SIP include enforceable emission limitations and 

other control measures to achieve and maintain the NAAQS. As part of its attainment effort, 

Clark County included the Section 90 series of the Clark County Air Quality Regulations 

(AQRs) in the PM10 SIP. These rules include control requirements for open areas, construction 

activities, and vacant lands, and their implementation and enforcement have significantly 

contributed to the improvement of air quality in the Las Vegas Valley. 

Clark County is now obligated to maintain the valley’s improved air quality status. Clark County 

is not proposing amendments to the Section 90-series AQRs with this maintenance plan; in fact, 

the Section 90 series is vital to maintaining compliance with the PM10 NAAQS. Construction 

activities and vacant lands are the two source categories with the highest PM10 emissions; while 

their controls are not without cost, Clark County cannot relax PM10 measures applicable to HA 

212 at this time. Section 110(l) of the CAA states: “[EPA] shall not approve a revision of a plan 

if the revision would interfere with any applicable requirement concerning attainment and 

reasonable further progress....” 

4.4.1 Stationary Point and Nonpoint Source Regulations

PM10 stationary point sources in Clark County are generally industrial and utility combustion 

sources that emit 70 tons per year or more. Nonpoint sources are commercial, small-scale 

industrial, and residential sources whose emissions fall below point source reporting levels and 

which are too numerous or too small to identify individually.

Clark County has numerous SIP and non-SIP regulations in place for stationary and nonpoint 

sources, notably AQR Sections 12.0–12.13 and Section 21. Clark County also enforces several 

federal regulations as part of its emissions control program, including 40 CFR 61 and 63, 

“National Emissions Standards for Hazardous Air Pollutants” (under AQR Section 13) and 40 

CFR 60, “Standards of Performance for New Stationary Sources” (under AQR Section 14). 

As part of its 2001 PM10 SIP submittal, Clark County adopted comprehensive fugitive dust 

controls (the Section 90 series). The following list outlines these AQRs: 

• Section 90 requires stabilization of open areas and vacant lands to prevent entrainment of 

particulate matter. 

• Section 91 requires stabilization of unpaved roads, and paving of unpaved roads when 

traffic volume is equal to or greater than 150 vehicles per day. It also prohibits 

construction of new unpaved roads in public thoroughfares. 

• Section 92 requires stabilization of unpaved parking areas, including material handling 

and storage yards, and generally prohibits construction of new unpaved parking lots in 

the nonattainment area. 

• Section 93 sets forth requirements for paved roads, street sweeping equipment, and 

certain other dust-mitigating devices. 
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• Section 94 establishes permitting and dust control requirements for construction 

activities. This regulation incorporates by reference a comprehensive dust control 

handbook (DAQEM 2003) that outlines Best Management Practices (BMP) for 

construction activities. 

The Clark County dust program met EPA’s most stringent measures requirements at the time of 

adoption, and it remains state-of-the-art because of Clark County’s SIP commitment to evaluate 

the feasibility of revising the Section 90 rules. This resulted in numerous amendment adoptions 

in 2002 and 2003. 

4.5 ADDITIONAL EMISSION REDUCTION CONTROL MEASURES

4.5.1 Regional Haze Rule

This rule, promulgated in July 1999, mandates emission reductions to achieve natural visibility 

levels in mandatory Class I areas by 2064. Control measures principally address light-scattering 

and -absorbing aerosols. Several of these measures will be implemented throughout the western 

states, i.e., Best Available Retrofit Technology will be installed on older emissions units. The 

measures will be operational by January 1, 2015, or no later than five years after approval of 

state regional haze SIPs, whichever comes first. Most western states, including Nevada, have 

submitted regional haze SIPs; EPA proposed full approval of Nevada’s plan on June 22, 2011

(76 FR 36450).

4.5.2 Transportation Conformity

Clark County will continue to work closely with the Regional Transportation Commission of 

Southern Nevada (RTC) to assure that regional transportation plans and transportation 

improvement programs in HA 212 are consistent with and conform to Clark County’s air quality 

program requirements, including the PM10 SIP. 

4.5.3 Clark County Natural Events Action Plan 

In April 2005, the BCC adopted the Natural Events Action Plan for High-Wind Events: Clark 

County, Nevada (NEAP). The NEAP protects public health by warning of impending wind 

events: dust control permittees are reminded to employ all BMP for dust control, the public is 

notified of wind events in progress, and Clark County citizens are educated on the health hazards 

of PM. Public notifications include information on how residents can reduce airborne 

particulates by avoiding certain individual or collective particulate-emitting activities, especially 

during high-wind events. 

Protection of public health is the principal goal of the NEAP, which contains detailed 

information about actions implemented in Clark County to minimize public exposure to 

potentially high levels of PM10 caused by winds. Its primary components are: 

• A high-wind event notification system that includes an early warning procedure. 

• Education and outreach programs. 
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• Enhanced enforcement and compliance programs to reduce emissions. 

• Submittal of required documentation to EPA in the event of an exceedance. 

The only guidance in effect when Clark County developed its NEAP was an EPA policy memo,

“Areas Affected by PM10 Natural Events” (EPA 1996), which allowed air quality data to be 

flagged so it would not count toward an area’s attainment status if it could be shown there was a 

clear causal relationship between the data and one of three categories of natural events: volcanic 

and seismic activity, unwanted wild land fires, or high-wind events. On March 22, 2007, EPA 

promulgated a final rule (72 FR 13560) addressing the review and handling of air quality 

monitoring data influenced by “exceptional events,” i.e., those for which the normal planning 

and regulatory process established by the CAA is not appropriate. 

Clark County’s NEAP procedures have been very effective since their adoption, and changes 

reflecting the exceptional event final rule have created an even stronger program. Clark County 

now provides more information to EPA in submittal packages, and has improved early warning 

processes to better inform the public. 

Clark County continually updates its natural events program. One example is the high-wind 

exceptional event exercise drill, which is conducted each year before the windy season to 

refamiliarize staff with procedures and identify potential problem areas. Additionally, 

construction notices are issued that proactively warn sources of winds that are below NEAP 

event levels but could still impact public health. These and other enhancements provide essential 

tools for regularly evaluating operational processes to help reduce the health and environmental 

effects of PM on county residents.

4.6 AIR QUALITY TREND ANALYSIS: WEIGHT OF EVIDENCE

Clark County performed an air quality trend analysis for the period between 2001 and 2010 

using quality-assured data from EPA’s AQS database (Figure 4-2). The purpose was to use a 

weight-of-evidence approach to support the attainment demonstration of the PM10 NAAQS.

For the demonstration, a regressed logarithmic trend line was fit to the data points in lieu of a 

linear trend line because of its smoothing effect on the rate of change of the dependent variable 

(PM10 design values, or y), and because the trend line is more representative of real world

conditions (i.e., the line is prevented from dropping below zero (the lower asymptote) due to all 

values of y > 0). 

The R-squared (R2

) of the regression—commonly called the “goodness-of-fit”—is the percentage 

of variance in y that can be accounted for by the independent variable (years, or x). An R2 greater 

than 0.80 suggests that the regression line equation (y = 62.32ln(x) + 255.24) strongly 

approximates the data points, and provides a significant level of credibility for the weight-ofevidence attainment demonstration. The R2 of this regression is 0.9366.

Clark County is confident that future PM10 concentrations will continue to trend downward with 

the maintenance control measures described in Section 4.4 and continued enforcement of the 

PM10 control program.
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Figure 4-3. Actual and Log PM10 Trend.
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5.0 REQUIREMENTS FROM SECTION 110 AND PART D OF THE 

CLEAN AIR ACT AMENDMENTS

5.1 INTRODUCTION

The fourth required component of a redesignation request is verification that Clark County meets 

CAA Section 110 and Part D requirements. This section provides that verification.

5.2 SECTION 110 REQUIREMENTS

Before EPA can redesignate the Clark County PM10 nonattainment area, the provisions of CAA 

Sections 110(a)(2) and 110(l) must be satisfied. Section 110(a)(2) addresses the general 

requirements for SIPs; Section 110(l) prevents approval of SIP revisions if components of the 

plan would interfere with any applicable requirement concerning attainment, with reasonable 

further progress towards attainment of a NAAQS, or with any other applicable CAA 

requirement. 

5.2.1 Section 110(a)(2)

This CAA section contains the following SIP requirements:

1. Establishment and implementation of enforceable emission limitations.

2. Monitoring, compilation, and analysis of ambient air quality data.

3. Preconstruction review and permitting of new and modified major stationary sources.

4. Consultation with, and provisions for, the participation of affected local governments.

5. Assurance the state has adequate funds and authority to enforce the SIP and associated 

regulations.

6. Establishment of permit fees for stationary sources.

Nevada Revised Statutes (NRS) 445B.500 addresses the establishment, administration, and 

enforcement of programs for controlling air pollution in Nevada. In Clark County, these 

programs are administered and enforced by the Clark County Department of Air Quality. The 

department has more than 100 staff members and an annual budget of approximately $28 million 

to administer, implement, and enforce the CAA, including the development of air quality plans 

and regulations applicable to the PM10 maintenance area. 

Clark County’s current air quality program meets all the provisions required by Section 

110(a)(2). If Clark County becomes unable to meet any of these provisions, NRS 445B.520 and 

445B.530 allow the State Environmental Commission to assume jurisdiction over the local air 

quality management program to ensure that CAA requirements are met. EPA also has authority 

to impose sanctions on a state if it “finds that any requirement of an approved plan (or approved 

part of a plan) is not being implemented” (CAA, Section 179).
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5.2.2 Section 110(l)

CAA Section 110(l) requires that SIP revisions not interfere with requirements for attainment or 

reasonable further progress regarding other criteria pollutants, or with any other CAA 

requirements. Since this plan proposes no changes to current emission reductions control 

measures, it poses no interference with Clark County’s progress towards continued attainment of 

the carbon monoxide or ozone NAAQS. The only other criteria pollutant in Clark County is 

PM2.5, for which Nevada is currently designated as attainment/unclassifiable under CAA Section 

107(d).

5.3 PART D REQUIREMENTS

Sections 172(c) and 176(c) in Part D of the CAA lay out requirements that apply to all areas 

designated as nonattainment because of a NAAQS violation. 

5.3.1 Section 172(c) 

This CAA section contains general requirements for maintenance plans, including:

1. Implementation of reasonably available control measures, including reasonably available 

control technologies, for existing sources.

2. Reasonable further progress for existing sources.

3. A current EI, and periodic EIs every three years until attainment.

4. Identification and quantification of allowable emissions for new and modified stationary 

sources.

5. A stationary source permitting program.

6. Other measures, including enforceable emission limitations, additional control measures,

and a schedule for compliance.

7. Compliance with Section 110 provisions.

8. Contingency measures.

Clark County’s current air program, in conjunction with the components of this plan, meets all 

Section 172(c) provisions. 

5.3.2 Section 176(c)

This section contains transportation and general conformity provisions applicable in maintenance 

areas. The transportation conformity process ensures transportation plans, programs, and projects 

in maintenance areas do not create new violations of the NAAQS, do not increase the frequency 

or severity of NAAQS violations, and do not delay timely attainment of the NAAQS. It does not 
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allow federal agencies to engage in, support, or provide financial assistance for licensing, 

permitting, or approving any project unless the project conforms to the SIP.

6.0 MAINTENANCE PLAN

6.1 INTRODUCTION

The fifth required component of an area’s redesignation request is the fulfillment of CAA 

Section 107(d)(3)(E) requirements. These specify that for an area to be redesignated to 

attainment, EPA must approve a maintenance plan that meets all the conditions of CAA Section 

175(a), including a comprehensive and accurate demonstration of continued maintenance of the 

PM10 NAAQS for 10 years after redesignation. 

Two approaches are acceptable for demonstrating maintenance of the NAAQS (EPA 1992). The 

first, the emissions projections approach, compares a projected EI with an attainment EI. The 

second is a complex analysis using gridded dispersion modeling. Clark County chose the 

emissions projection approach, comparing an EI for the baseline year (2008) to an EI for the 

maintenance year (2023). The maintenance year was chosen to allow EPA 18 months after

receipt of a complete submittal to process Clark County’s redesignation request.

The baseline EI represents an emission level that would not cause a NAAQS violation—the 

design value concentration of 98 μg/m3 on the design day of April 15, 2008. If the projected 

maintenance year concentration remains at or below the baseline year concentration, continued 

maintenance is demonstrated. In addition, the maintenance demonstration includes a comparison 

between an interim year (2015) concentration and the baseline year concentration to show 

maintenance throughout the 10-year period after redesignation, not just in the maintenance year.

A roll-forward model was also used to support the attainment demonstration

6.1.1 Inventory Domain 

Although EPA requires an EI for the entire nonattainment area, attainment can be demonstrated 

for a larger or smaller area if there are compelling reasons to do so. Use of smaller areas can 

focus the attainment analysis on relevant areas and key anthropogenic sources that affect highconcentration monitors and population areas.

In choosing a domain boundary, such factors as wind patterns and source, monitor, and receptor 

locations (e.g., population centers) should be considered (EPA 1991). The boundary should be 

established such that phenomena at the boundary have little effect on the center. Background 

concentrations should account for sources not explicitly modeled (40 CFR 51, App. W; EPA 

1987, Appendix D; and EPA 1981, p.27.)

Based on these criteria, and consistent with the boundary used in the PM10 SIP attainment 

demonstration, Clark County selected the BLM disposal area as the domain for the maintenance 

demonstration. Its edges are areas of low emission density that have little effect on the places of 

concern (i.e., locations with high monitored values). Sources in the outlying areas are effectively 

accounted for by including background concentrations in the inventory. This approach is 
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supported by modeling work conducted in Clark County for previous studies (e.g., DRI 1997) 

that discovered sources of PM10 have a small radius of influence.

HA 212 covers roughly 960,000 acres, over half of which are under federal control:

• Bureau of Reclamation: 9,689 acres

• Desert National Wildlife Refuge: 226,728 acres

• Lake Mead National Recreational Area: 1,148 acres

• Nellis Air Force Base and Ranges: 25,124 acres

• Red Rock Canyon National Conservation Area: 195,780 acres 

• Humboldt-Toiyabe National Forest: 60,073 acres.

Nonattainment area EIs were not projected for future years because Clark County based the 

attainment demonstration on the BLM disposal area. The demonstration was limited to this area 

for several reasons, including:

• All violations of the 24-hour NAAQS happened within the BLM disposal area.

• More than 99 percent of the population in the nonattainment area lives within the BLM 

disposal area.

• More than 98 percent of the vehicle miles traveled (VMT) in the nonattainment area are 

within the BLM disposal area.

• The topography within the BLM disposal area is relatively uniform, a factor that 

minimizes modeling uncertainty, whereas the outlying areas of the nonattainment area 

vary by over 8,000 feet – a factor that increases modeling uncertainty.

• All man-made emissions of PM10, except one major stationary source and small 

percentages of minor sources, unpaved road dust, and paved road dust, lie within the 

BLM disposal area.

• Focusing on the BLM disposal area places a greater emphasis on sources closest to 

human receptors.

Before Clark County attained the PM10 NAAQS, all measured violations occurred within the 

BLM disposal area, which is also where nearly all anthropogenic emissions within the 

nonattainment area occur. As part of a network saturation study (DAQEM 2007b), three 

samplers were deployed outside the BLM disposal area but within the nonattainment area. No 

violations were recorded.
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6.2 TRANSPORTATION INPUT DATA

Table 6-1 summarizes the transportation data (i.e., daily VMT) used to develop the EIs in 

Section 6.4 (RTC 2008). All other input data used in developing the EIs, such as vehicle fleet 

mix, seasonal/day-of-the-week adjustment factors, and hourly activity profiles, have been 

updated with the most current data available. 

Table 6-1. Daily VMT Data Used to Develop Emission Inventories

Year VMT 

(HA 212)

VMT 

(BLM Disposal Area)

Baseline (2008) 39,377,980 38,795,925

Interim (2015) 48,886,838 48,073,477

Maintenance (2023) 63,994,191 62,735,685

6.3 EFFICIENCY AND EFFECTIVENESS FACTORS

Control efficiency, rule effectiveness, and rule penetration factors were applied to the baseline 

emissions of point and nonpoint source categories affected by the AQRs, when applicable. The 

term “control efficiency” includes capture efficiency for point sources, which defines the

percentage of emissions from a source captured by a control device. Rule effectiveness reflects 

the actual capability of a regulatory program to achieve the emission reductions required by 

regulation. Rule penetration is the assumed percentage of emissions of the targeted Source 

Classification Code subject to the requirements of a rule.

6.4 EMISSION INVENTORY TYPE CATEGORIES

The PM10 EIs were derived from estimates developed for categories including point sources, 

nonpoint sources, mobile, and banked emission reduction credits (ERCs). The following sections 

briefly discuss each category and its estimated emissions; more detailed explanations of the 

estimates are provided in the technical support document (Appendix A).

6.4.1 Point Sources

Clark County’s point source inventory includes all airport/aircraft and Title V stationary sources 

inside HA 212, as well as minor stationary sources clustered together closely enough to be 

considered potential hot spots of emissions within the BLM disposal area. 

Clark County has authority over most emission units in the county; however, Nevada state law

places certain electric steam-generating units in the county under NDEP jurisdiction. The 

facilities within the nonattainment area over which NDEP has or had authority, partial or whole, 

are:

• NV Energy Clark Station. The emission units at this facility that once operated under 

NDEP’s jurisdiction have been decommissioned. However, emission units under Clark 

County’s jurisdiction still operate at this facility. 
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• NV Energy Sunrise Station

The status of all units at these facilities, whether decommissioned or in current operation, was 

properly considered in the point source EIs. 

. Certain emission units at this facility operate under NDEP’s 

jurisdiction, while others operate under Clark County’s jurisdiction.

All point source EIs for the baseline year (2008) were obtained from reports submitted by the 

individual sources, and reflect actual emissions for that calendar year. This information was 

quality assured/quality controlled by Clark County staff.

Projections were performed for 2015 and 2023 for each facility (except Nellis Air Force Base) 

using the 2008 EI and Economic Growth Analysis System, version 5.0, Source Classification 

Code growth factors, which are based on the Regional Economic Models, Inc. 6.0 model. 

Projections for Nellis were estimated using actual 2008 emissions and projections supplied by 

the source. 

Linear regression was used to establish emissions projections for 2015 and 2023. To account for 

the possibility of a new power plant or expansions of existing plants, emissions from a 

theoretical power facility were included for the 2015 and 2023 EIs. 

6.4.2 Nonpoint Sources

Nonpoint sources of emissions are those that fall below point-source reporting levels and are too 

numerous or small to identify individually. Generally, they are small-scale industrial or

residential operations that use emission-generating materials or processes. 

Nonpoint source emission calculations are estimated as countywide totals rather than as 

individual source emissions. With some exceptions, these emissions are calculated by 

multiplying an EPA-approved factor (emissions per unit of activity) by the appropriate activity 

or activity surrogate responsible for generating emissions. When available, actual activity data is 

used; when data is unavailable, surrogates are used, including county population or employment 

data by industry type (and, when applicable, by growth factors from the Economic Growth 

Analysis System). 

6.4.3 Mobile Sources 

The mobile sources category consists of on-road and non-road sources and locomotives. On-road 

mobile sources consist of cars, trucks, motorcycles, and other motor vehicles traveling on public 

roadways. Emissions from this category are vehicle exhaust, brake wear, and tire wear, all 

calculated using the MOVES2010a model. Re-entrained road dust from on-road sources, while 

included in the mobile source budgets for transportation conformity, is addressed in the nonpoint 

sector of this plan. Re-entrained road dust emissions for on-road emissions were calculated using 

the January 2011 version of AP-42.

Non-road mobile sources consist of a wide variety of equipment types that either move under 

their own power or can be moved from site to site. Exhaust emissions were calculated using 
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EPA’s NONROAD model. Re-entrained unpaved road dust, while included in the mobile source 

budgets, is addressed in the nonpoint portion of this plan.

The third and last subcategory is locomotives, whose emissions were categorized separately from 

the nonpoint source inventory.

6.4.4 Banked Emission Reduction Credits

If a source voluntarily reduces emissions beyond the permit limits, and/or implements controls 

beyond what is required, it may apply for ERCs pursuant to Section 12.7. If the ERCs are 

approved, they will be banked for future use or transacted in accordance with the AQRs. Clark 

County may grant reciprocity for use of ERCs banked by NDEP within the county if the ERCs 

comply with all AQR requirements at the time of redemption, and NDEP has the authority to 

grant reciprocity for use of Clark County-banked ERCs at sources in Clark County that it 

permits. NDEP has jurisdiction over permitting, compliance, and ERC banking for sources in the 

county that burn fossil fuels in a boiler to produce steam for the production of electricity (NRS

445B.500); all other emission units in the county are under the jurisdiction of Clark County.

Clark County chose to account for all ERCs in the maintenance year (2023) because ERCs can 

be used in nonattainment areas to offset emissions of new major sources and major modifications 

at existing major sources. ERC emissions are accounted for in the point source emissions growth

estimated for 2023 because point source emissions growth and ERCs largely overlap. To be 

conservative, however, Clark County is not considering the potential overlap in this 

demonstration.

6.5 SUMMARY OF EMISSION INVENTORIES

Table 6-2 summarizes the 2008, 2015, and 2023 PM10 EIs for the BLM disposal area in tons per 

day (tpd) for five source categories. In particular, emissions from wind erosion of vacant lands 

show a significant decrease over time as construction within the BLM disposal area consumes 

vacant lands. 
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Table 6-2. Summary of Total Daily PM10 Emissions (tpd)

Source 2008 (tpd) 2015 (tpd) 2023 (tpd)

Point Emissions:

Subtotal: 2.19 2.60 2.88

Nonpoint Emissions:

Fuel Combustion 1.23 1.29 1.38

Residential Wood Combustion 1.89 1.90 1.92

Locomotive 0.06 0.06 0.06

Paved Road 30.85 38.04 48.78

Unpaved Road 5.84 6.51 7.49

Commercial Cooking 2.19 2.52 2.83

Mineral Processing (concrete, gypsum) 0.28 0.34 0.40

Mineral Processing (stone) 0.15 0.18 0.21

Asphalt 0.33 0.37 0.40

Wind Erosion (Construction) 183.97 217.70 249.21

Construction 30.93 37.69 41.22

Sand & Gravel 0.42 0.51 0.60

Open Burning 0.02 0.02 0.02

Wind Erosion (Vacant Lands) 439.05 288.16 122.77

Structural Fires 0.02 0.02 0.03

Vehicle Fires 0.03 0.03 0.04

Subtotal: 697.23 595.34 477.36

On-road Emissions:

Subtotal: 3.08 2.52 2.75

Nonroad Emissions:

Subtotal: 3.74 2.95 1.94

Emission Reduction Credits:

Subtotal: 0.31 0.31 0.31

Total: 706.55 603.72 485.24

Figures 6-1 and 6-2 show emission distributions in 2008 and 2023, respectively, and Figure 6-3

shows the nonpoint source category EIs for each of the three demonstration years. Appendix A 

provides detailed information on the methodologies used to estimate EIs. 

In summary, total PM10 emissions decrease 31 percent (221 tpd) between 2008 and 2023. 
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Figure 6-1. Emission Distribution in 2008.

Figure 6-2. Emission Distribution in 2023.
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Figure 6-3. Nonpoint Emissions in the BLM Disposal Area.

6.6 MAINTENANCE DEMONSTRATION

CAA Section 175(a) requires each request for redesignation to be accompanied by a SIP revision 

that provides for maintenance of the NAAQS for at least 10 years after redesignation. EPA 

(1992) recommends using the ratio of baseline emissions to the design value, adjusted for 

background concentration, to determine whether projected emissions for a future year will 

predict concentrations in compliance with the NAAQS. 

Table 6-2 and Figure 6-4 show that projected future-year PM10 emissions are less than 2008 

emissions. Since projected emissions for 2015 and 2023 are less than 2008 emissions,

maintenance of the NAAQS is demonstrated. 
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Figure 6-4. Comparison of 2008, 2015, and 2023 PM10 Emissions.

The EIs show a downward trend in PM10 emissions, mainly due to the control measures 

described in Section 4.4. No emission increases are expected that will threaten the demonstration 

of attainment; even if new sources emerge, the 2023 EI is well below the 2008 EI. 

6.7 ROLLBACK MODEL

EPA recommends a combination of receptor and dispersion models, paired with reliable 

emission projections, to model attainment in a future year. However, receptor models cannot 

quantify absolute PM10 emission estimates in some circumstances, such as urban locations where 

a large fraction of particulate emissions come from nontraditional sources (e.g., construction 

operations or wind-blown fugitive dust). Dispersion models also have limitations that make 

modeling fugitive dust difficult, since uncertainties regarding emission rates, deposition rates, 

and plume characteristics of course fraction crustal particulates pose problems in obtaining valid 

results.

For these reasons, Clark County adopted the proportional rollback model approach to 

demonstrate attainment in the PM10 SIP. Since it was an accurate predictor, the same approach 

was used to demonstrate continuous (maintenance) attainment for 2015 and 2023.
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The rollback model assumes a linear relationship between PM10 emissions from sources and their 

contribution to measured PM10 levels in ambient air: for example, if 25 percent of emissions in 

an area come from wind erosion of vacant lands, the model assumes that 25 percent of the 

ambient concentration measured by a monitor in that area (minus the background concentration, 

which remains constant) came from this wind-entrained soil. The proportional rollback model 

assumes that any reduction or increase in emissions will cause a corresponding reduction or 

increase in the ambient concentration measured at the monitoring station. The basic steps are:

1. Determine the representative monitoring station(s) and design value.

2. Define the background concentration as the lowest PM10 value recorded at an upwind 

monitoring station on the same day or during the same time period.

3. Estimate the anticipated increase or decrease in emissions from each source.

4. Apply the same percentage of increase or decrease from emissions to the design 

concentration.

5. Calculate the anticipated ambient concentration after the emissions change. 

The PM10 SIP analyzed five microscale sites, in addition to completing a valley-wide analysis. 

Since the areas surrounding those five sites are now built out, they are no longer considered 

representative. Moreover, as the PM10 SIP stated, the percent reduction for attainment was equal 

or higher valley-wide than at the microscale sites. The rollback analysis for this maintenance 

plan therefore uses a valley-wide scale.

The analysis used a design value of 98 μg/m3, minus the background concentration of 37 μg/m3

measured at Jean on the design day (April 15, 2008). The Jean monitoring station is upwind of 

the nonattainment area, so it is often used to represent background levels in Clark County. 

The referenced design-day and future-year emission calculations do not include contributions

from the secondary formation of particulates, and the rollback method does not account for 

nonlinear secondary particulate formation. The PM10 SIP accounted for this by adding 3.5 μg/m3

to the background concentration, based on past chemical mass balance studies. Including 3.5 

μg/m3 to represent secondary PM, the background level was 40.5 μg/m3

. Subtracting this

background level from the design value yielded a concentration due to anthropogenic emissions 

of 57.5 μg/m3 (98 μg/m3 – 40.5 μg/m3

).

The following PM10 concentrations are anticipated in 2015 and 2023.

• Future year 2015: 

– Total 2008 emissions = 706.55 tpd (Table 6-2)

– Total 2015 emissions = 603.72 tpd (Table 6-2)

– Total 2008 anthropogenic concentration = 57.5 μg/m3
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– Anthropogenic concentrations for 2015, determined by multiplying the 2008 anthropogenic concentration by the ratio of 2015 emissions to 2008 emissions:

57.5 μg/m3 • (603.72 tpd / 706.55 tpd) = 49.13 μg/m3

 

– Adding back the background concentration, which is presumed constant: 

49.13 μg/m3 + 40.5 μg/m3 = 89.63 μg/m3

• Future year 2023: 

– Emissions = 485.24 tpd (Table 6-2)

– Concentration = (57.5 μg/m3 • (485.24 tpd / 706.55 tpd)) + 40.5 μg/m3 = 79.99 μg/m3

The concentrations predicted by the rollback analysis show that the 24-hour PM10 NAAQS will 

be maintained through 2023.

6.8 MONITORING NETWORK AND VERIFICATION OF CONTINUED 

ATTAINMENT

After being redesignated to attainment status, Clark County will continue to operate its air 

quality monitoring network to verify attainment of the PM10 NAAQS. Annual review of the eight 

State and Local Air Monitoring System monitors will be conducted in accordance with 40 CFR 

58.20(d) to ensure the system continues to meet monitoring objectives.

6.9 CONTINGENCY MEASURES

CAA Section 175A(d) requires that a maintenance plan contain contingency provisions to assure 

prompt correction of any violation of the NAAQS. Contingency plans must also describe the 

methods that will be used to ensure the measures in the plan are adopted quickly if triggered. 

EPA (1992) states that a contingency plan does not have to contain fully adopted contingency 

measures, but should at least have three primary elements:

1. A list of potential contingency measures.

2. An explanation of the tracking and triggering mechanisms that will determine when 

contingency measures are needed.

3. A description of the process for recommending and implementing contingency measures,

with specific timelines for action.

6.9.1 Potential Contingency Measures

Clark County proposes the following potential control measures as part of this maintenance plan:

• Implementing a new dust control permit requirement for certain short-term activities that 

disturb, or have the potential to disturb, soils that emit PM into the atmosphere, such as 
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August 2012 12

mechanized weed abatement, fairs, carnivals, Christmas tree and Halloween pumpkin 

lots, art sales, and similar activities.

• Conducting a comprehensive review and update of the Construction Activities Dust 

Control Handbook (DAQEM 2003) to increase the effectiveness of existing BMP and to

identify and develop new BMP. Updated BMP may include management practices for 

soil-disturbing activities not covered in current practices. Potential new BMP include 

practices for roadway and detention basin maintenance activities.

• Reviewing the dust mitigation plan requirements in AQR Section 90, giving 

consideration to reducing the acreage-trigger thresholds and incorporating additional 

mitigation plan criteria. Also reviewing Section 92, giving consideration to lowering 

applicability thresholds for unpaved parking lots.

• Reassigning staff to provide additional field enforcement of the AQRs that control 

sources of fugitive dust emissions.

• Mapping construction activities during inspections to collect PM10 data to provide greater 

accuracy for calculating actual emissions from construction projects.

• Developing a new dust control database that will strengthen oversight of dust control 

permits and improve source compliance.

• Amending current fugitive dust regulations to incorporate new technologies and measures 

for controlling emissions and preventing them from crossing property lines or causing a 

nuisance. 

Clark County may use additional strategies to address any future violations in the most 

appropriate and effective manner.

6.9.2 Tracking and Triggering Mechanisms

The primary tracking mechanism will be Clark County’s continuous PM10 monitoring network 

(Section 6.9). Clark County will examine ambient air quality monitoring data within 30 days of 

collection to determine if the PM10 NAAQS has been exceeded. 

The primary trigger mechanism will be a confirmed violation of the PM10 NAAQS, defined as 

more than one exceedance day per year averaged over a three-year period. The trigger date will 

be 60 days from the date a monitoring station records a reading that results in a design value

equal to or greater than the PM10 NAAQS. 

The triggering of the contingency plan would not automatically require a revision of the PM10

SIP, nor would Clark County necessarily be redesignated to nonattainment. Instead, it would 

have a period of time to correct the violation by implementing one or more contingency 

measures. If violations continued after contingency measures were implemented, additional 

measures would be implemented until the violations were corrected. 
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August 2012 13

The RTC’s ongoing regional transportation planning process will serve as another means of 

tracking mobile source emissions, since the RTC revises its transportation improvement plan 

every three years and these revisions are subject to a transportation conformity finding. That

process will serve as a periodic check on maintaining the VMT and mobile source emissions 

projections in this plan.

6.9.3 Action Resulting from Trigger Activation

Within 45 days of the trigger date, Clark County must notify EPA that an internal review process 

will begin to evaluate potential contingency measures. Within 90 days of that notification, Clark 

County must send EPA an information report outlining recommended actions. Clark County will 

then solicit stakeholder involvement through public forums (e.g., PM10 working groups) to refine 

the process of implementing the recommended actions. The BCC and/or Nevada State 

Environmental Commission will hold one or more public hearings to consider the recommended 

contingency measures, along with any others that may address the confirmed violation. The 

necessary measures must be adopted and implemented within 18 months of submittal of the 

information report to EPA.

6.10 SUBSEQUENT MAINTENANCE PLAN REVISIONS

Section 175A(b) requires that, eight years after redesignation of any area to attainment under 

Section 107(d), the state shall submit an additional revision of the applicable SIP that shows how 

the NAAQS will be maintained for 10 years after the expiration of the first 10-year period. Clark 

County commits to the submittal of a revised maintenance plan eight years after HA 212 is 

redesignated to attainment.
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August 2012 1

7.0 MOTOR VEHICLE EMISSIONS BUDGETS

Under CAA Section 176(c), transportation plans, programs, and projects in maintenance areas 

that are funded or approved under Title 23 of the U.S. Code or the Federal Transit Act must 

conform to the on-road motor vehicle emissions budgets (MVEBs) specified in the applicable 

SIP. In this case, 40 CFR 93.118 provides the criteria and procedures for MVEBs. 

The MVEB establishes a cap on motor vehicle-related emissions that cannot be exceeded by 

predicted transportation system emissions. The emissions budget applies a ceiling on emissions 

in the year for which it is defined, and for all subsequent years until a different budget is defined 

for another year or a SIP revision modifies the budget. Table 7-1 lists 2008, 2015, and 2023 

PM10 mobile source emissions for the BLM disposal area.

Table 7-1. BLM Disposal Area PM10 Mobile Source Emissions (tpd)

Source 2008 2015 2023

Paved road 30.85 38.04 48.78

Unpaved road (public) 0.28 0.32 0.36

Vehicle (exhaust, brake wear, and tire wear) 3.08 2.52 2.75

Road construction 1.54 1.87 2.05

Construction track-out 0.25 0.30 0.33

Wind erosion (road construction) 6.53 7.73 8.85

TOTAL 42.53 50.78 63.12

EPA's conformity regulation (40 CFR 93.124) allows a SIP to quantify explicitly the amount by 

which motor vehicle emissions could be higher while still demonstrating compliance with the 

maintenance requirement. The plan can then allocate some or all of this additional “safety 

margin” to the emissions budgets for transportation conformity purposes. The safety margin for 

this maintenance plan is 52 μg/m3, the difference between the NAAQS value (150 μg/m3) and 

the design value (98 μg/m3

). Using the methodology of Section 6.7, the MVEBs were 

recalculated to include a safety margin.

The mobile source budgets for 2008, 2015, and 2023 (Table 7-1) were adjusted to 141.41 tpd, 

which match the emission budgets in the PM10 SIP and were thus approved by EPA in 2004 (69

FR 32273). Clark County’s request for the same PM10 budget figure is both for consistency and 

for RTC’s familiarity with it in transportation planning. The mobile source budgets in Table 7-1 

were increased by 98.88 tpd, 90.63 tpd, and 78.29 tpd for 2008, 2015 and 2023, respectively. 

Table 7-2 lists the adjusted emission inventories for 2008, 2015, and 2023 based on the mobile 

budget increases.

The design values were recalculated using the rollback model. These parameters were used to 

recalculate the estimated concentrations for 2008, 2015, and 2023. The revised maintenance 

demonstration for 2008, 2015, and 2023 still shows maintenance of the PM10 standard: it 

estimates maximum PM10 concentrations of 106 μg/m3 in 2008, 97 μg/m3 in 2015, and 86 μg/m3

in 2023.
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August 2012 2

• Adjusted 2008 data:

– Pre-adjusted total 2008 emissions = 706.55 tpd (Table 6-2)

– Desired mobile source emissions budget = 141.41 tpd 

– Pre-adjusted 2008 mobile source emissions budget = 42.53 (Table 7-1)

– Since total 2008 emissions include the pre-adjusted 2008 mobile budgets, the latter 

are subtracted from the total and then the desired budgets are added: 

706.55 tpd - 42.53 tpd + 141.41 tpd = 805.43 tpd (adjusted 2008 EI)

– To determine the adjusted 2008 design value: 

o Pre-adjusted anthropogenic 2008 concentration = 57.5 μg/m3 (Section 6.7)

o Pre-adjusted total 2008 EI = 706.55 tpd (Table 6-2)

o Adjusted 2008 EI = 805.43 tpd 

o Background concentration = 40.5 μg/m3 (Section 6.7)

o To determine the adjusted 2008 anthropogenic concentration, the pre-adjusted 

2008 anthropogenic concentration is multiplied by the ratio of the adjusted 2008 

emissions to the pre-adjusted 2008 emissions: 

57.5 μg/m3 • (805.43 tpd / 706.55 tpd) = 65.5 μg/m3

o Because the background concentration, which is constant, is not accounted for in 

this anthropogenic concentration, it is now added to determine the adjusted 2008 

design concentration: 65.5 μg/m3 + 40.5 μg/m3 = 106 μg/m3

• Adjusted 2015 data:

– Pre-adjusted total 2015 emissions = 603.72 tpd (Table 6-2)

– Desired mobile source emissions budget = 141.41 tpd 

– Pre-adjusted 2015 mobile source emissions budget = 50.78 (Table 7-1)

– In that the total 2015 emissions include the pre-adjusted 2015 mobile budgets, the 

latter are subtracted from the total and then the desired budgets are added: 

603.72 tpd – 50.78 tpd + 141.41 tpd = 694.35 tpd (adjusted 2015 EI)

– To determine the adjusted 2015 concentration:

o Pre-adjusted anthropogenic 2008 concentration = 57.5 μg/m3 (Section 6-7)

o Adjusted 2015 EI = 694.35 tpd
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o Pre-adjusted total 2008 emissions = 706.55 tpd (Table 6-2)

o Background concentration = 40.5 μg/m3 (Section 6-7)

o The pre-adjusted 2008 anthropogenic concentration is multiplied by the ratio of 

the adjusted 2015 emissions to the pre-adjusted 2008 emissions =

57.5 μg/m3 • (694.35 tpd / 706.55 tpd) = 56.5 μg/m3

o Because the background concentration, which is constant, is not accounted for in 

this anthropogenic concentration, it is now added to determine the adjusted 2015 

design concentration = 56.5 μg/m3 + 40.5 μg/m3 = 97 μg/m3

• Likewise, the adjusted 2023 data is calculated as:

– Adjusted 2023 EI = 485.24 tpd – 63.12 tpd +141.41 tpd = 563.53 tpd 

– Adjusted 2015 anthropogenic concentration: (98 μg/m3 – 40.5 μg/m3

) • (563.53 tpd / 

706.55 tpd) = 45.9 μg/m3

– Adjusted 2023 design concentration = 45.9 μg/m3 + 40.5 μg/m3

= 86 μg/m3

Table 7-2. Revised Maintenance Demonstration

Parameter 2008 2015 2023

Concentration before adjustment (μg/m3) 98 89.63 79.99

Background (μg/m3) 40.5 40.5 40.5

EI (tpd) 706.55 603.72 485.24

Mobile emissions (tpd) 42.53 50.78 63.12

Adjusted EI (tpd) 805.43 694.35 563.53

Estimated concentrations after adjustment (μg/m3) 106 97 86

Upon an EPA affirmative adequacy finding and approval of the MVEBs, the budgets in Table 7-

3 will be used for conformity determinations in future regional transportation plans. 

Table 7-3. PM10 MVEBs for the BLM Disposal Area (tpd)

Year 2008 2015 2023

Original 42.53 50.78 63.12

Adjustment + 98.88 + 90.63 + 78.29

MVEB 141.41 141.41 141.41
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August 2012 1

8.0 REFERENCES

AQR Section 91. Fugitive Dust from Unpaved Roads, Unpaved Alleys, and Unpaved Easement 

Roads (amended 7/1/2004).

40 CFR 50. National Primary and Secondary Ambient Air Quality Standards. 

40 CFR 51. Requirements for Preparation, Adoption, and Submittal of Implementation Plans. 

40 CFR 58. Ambient Air Quality Surveillance.

40 CFR 60. Standards of Performance for New Stationary Sources. 

40 CFR 93. Determining Conformity of Federal Actions to State or Federal Implementation 

Plans. 

70 FR 20665. Clean Air Fine Particle Implementation Rule.

70 FR 71612. Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard-Phase 2; Final Rule to Implement Certain Aspects of the 1990 Amendments Relating to 

New Source Review and Prevention of Significant Deterioration as They Apply in Carbon Monoxide, Particulate Matter and Ozone NAAQS; Final Rule for Reformulated Gasoline.

75 FR 45485. Determination of Attainment for PM10 for the Las Vegas Valley Nonattainment 

Area, NV.

43 U.S.C. § 932. Mining Act of 1866 (repealed 1976).

43 U.S.C. § 1701. Federal Land Policy and Management Act of 1976. 

49 U.S.C. § 63. Federal Transit Act. 

CBER. 2010. “Historical Economic Data for Metropolitan Las Vegas.” Las Vegas, Nevada: University of Nevada, Las Vegas. http://cber.unlv.edu/snoutlk.html

DAQEM. 2001. PM10 State Implementation Plan for Clark County. Las Vegas, Nevada: Clark 

County Department of Air Quality.

DAQEM. 2003. Construction Activities Dust Control Handbook. Las Vegas, Nevada: Clark 

County Department of Air Quality. 

DAQEM. 2005. Natural Events Action Plan for High-Wind Events: Clark County, Nevada. Las 

Vegas, Nevada: Clark County Department of Air Quality.

DAQEM. 2007a. PM10 State Implementation Plan Milestone Achievement Report. Las Vegas, 

Nevada: Clark County Department of Air Quality. 
Request for Redesignation and Maintenance Plan for Particulate Matter (PM10)

August 2012 2

DAQEM. 2007b. Particulate Matter (PM10) Saturation Monitoring Study. Las Vegas, Nevada: 

Clark County Department of Air Quality.

DRI. 1997. Fugitive Dust and Other Source Contributions to PM10 in Nevada’s Las Vegas Valley. DRI Document No. 4039.2F1. Las Vegas, Nevada: Desert Research Institute. 

DRI. 2010. “Western Regional Climate Center Historical Climate Information.” 

www.wrcc.dri.edu/CLIMATEDATA.html

EPA. 1981. “Overview of Receptor Model Application to Particulate Source Apportionment.” 

Vol. I of Receptor Model Technical Series. EPA-450-4-81-016a. Washington, D.C.: U.S. Environmental Protection Agency. 

EPA. 1987. PM10 SIP Development Guideline. EPA-450/2-86-001. Washington, D.C.: U.S. Environmental Protection Agency. 

EPA. 1991. “Guideline for Regulatory Application of the Urban Airshed Model.” EPA-450/4-

91-013. Washington, D.C.: U.S. Environmental Protection Agency.

EPA. 1992. “Procedures for Processing Requests to Redesignate Areas to Attainment.” Memo, J.

Calcagni to EPA Regional Division Directors, dtd. 9/4/92.

http://www.epa.gov/ttn/oarpg/t5/memoranda/redesignmem090492.pdf

EPA. 1996. “Areas Affected by PM10 Natural Events.” Memo, M. Nichols to distribution, dtd. 

5/30/96. http://www.epa.gov/ttn/caaa/t1/memoranda/nepol.pdf

EPA. 2006. “Unpaved Roads.” Section 13.2.2 of Vol. I, “Stationary Point and Area Sources,” of 

AP-42, Compilation of Air Pollutant Emission Factors. 5th ed. Washington, D.C.: U.S. Environmental Protection Agency. 

EPA. 2008. “Ambient Air Monitoring Program.” Vol. II of Quality Assurance Handbook for Air 

Pollution Measurement Systems. EPA-454/B-08-003. Washington, D.C.: U.S. Environmental 

Protection Agency. 

EQM. 2006. An Inventory of Vacant Land Soil Stability and Unpaved Private Roads in the Las 

Vegas Valley Using Remote Sensing Imagery. Las Vegas, Nevada: Clark County Department of 

Air Quality. 

RTC. 2008. “Travel Demand Model Methodology and Air Quality Conformity Analysis.” Appendix 4 of Regional Transportation Plan 2009-2030. Las Vegas, Nevada: Regional Transportation Commission of Southern Nevada.