Carbon Monoxide

State Implementation Plan

Las Vegas Valley Nonattainment Area

Clark County, Nevada

August 2000
Acknowledgements

CLARK COUNTY Bruce Woodbury, Chair

BOARD OF COMMISSIONERS Erin Kenny, Vice-Chairman

 Yvonne Atkinson Gates 

 Dario Herrera

 Mary Kincaid

 Lance Malone

 Myrna Williams 

OFFICE OF THE Dale W. Askew, County Manager

COUNTY MANAGER Richard B. Holmes, Assistant County Manager 

 Mike Alastuey, Assistant County Manager 

DEPARTMENT OF John Schlegel, Director

COMPREHENSIVE PLANNING Phil Rosenquist, Assistant Director

 Christine Robinson, Planning Manager 

 Russell Roberts, Assistant Planning Manager 

 Clete Kus, Principal Planner 

 Zheng Li, Senior Planner 

 Russell S. Merle Jr., Intern Planner 

CLARK COUNTY Dr. Donald S. Kwalick, Chief Health Officer 

HEALTH DISTRICT AQD Michael Naylor, Director AQD 

AIR QUALITY William Cates, Clark County 

PLANNING COMMITTEE Dennis Mewshaw, McCarren International Airport 

 David James, Transportation Research Center, UNLV

 Clete Kus, Clark County

 Leslie Long, City of North Las Vegas 

 Susan Gray, City of Henderson

 Michael Naylor, Clark County Health District 

 Jerry Duke, Regional Transportation Commission 

 Steve Koon, City of BoulderCity 

 Russ Wilde, Nevada Department of Transportation 

 Lori Wohletz, City of Las Vegas 

 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 

PREFACE 

On September 21, 1999, the Clark County Board of Commissioners adopted the Las 

Vegas Valley Non-attainment Area Carbon Monoxide Air Quality Implementation Plan. 

Following the plan’s adoption and submittal, the U.S. Environmental Protection Agency,

Region IX, expressed concerns about several problematic areas that resulted in the 

emissions budget being found as inadequate. EPA also raised issues that affected the 

approvability of the plan. This revised plan has been prepared in response to these

concerns so that the U.S. EPA can find Clark County’s Carbon Monoxide State

Implementation Plan acceptable and approve it. 

This document is similar to the September 1999, Carbon Monoxide Air Quality 

Implementation Plan with the exception that additional clarification, documentation and 

technical analyses have been incorporated. In general, the changes are focused on

control measures, contingency measures and future year modeling. More specifically, 

additional discussion and changes have been made to the following control measures: 

Voluntary Transportation Demand Management/ Transportation Control Measure (page

4-4), the Cleaner Burning Gasoline program (page 4-2), the Alternative Fuel Vehicle

Program (page 4-8), and Inspection/Maintenance Technician Training and Certification

(page 4-7). With respect to contingency measures, a new set of measures has been

identified which include: On-Board Diagnostic testing, lowering of emission testing

cutpoints and on-road remote sensing of vehicles to identify high emitting vehicles (page

7-3). The final change relates to conducting additional micro-scale hot spot modeling

for future years for the purpose of validating the future year emission budgets (page 6-7 

and Appendix E). 

By addressing these concerns and incorporating these changes into a revised plan, it is 

now possible for the U.S. EPA to make an adequacy determination on the emission 

budget and ultimately approve this plan. Clark County is committed to working with the

EPA to gain approval of this plan and to attainment the carbon monoxide standard as 

expeditiously as possible. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN i 
Table of Contents

PREFACE ..................................................................................................................................i 

GLOSSARY OF ACRONYMS .................................................................................................iv 

LIST OF TABLES.....................................................................................................................vi 

LIST OF FIGURES................................................................................................................. viii 

CHAPTER ONE: INTRODUCTION 

 1.1 Introduction 1-1 

 1.2 Problem Statement 1-2 

 1.3 Physical Description 1-3 

 1.4 Climatological Setting 1-3 

1.5 Focus of this Plan 1-8 

CHAPTER TWO: MONITORING NETWORK AND TRENDS IN AIR QUALITY 

 2.1 Introduction 2-1 

 2.2 Background 2-1 

 2.3 Monitoring Network 2-2 

2.4 Trends in Carbon Monoxide Air Quality 2-5 

 

CHAPTER THREE: EMISSIONS INVENTORY SUMMARY 

 3.1 Introduction 3-1 

 3.2 Emissions Summary 3-2 

3.3 Total Annual Emissions 3-4 

 

CHAPTER FOUR: CONTROL MEASURES 

 

 4.1 Introduction 4-1 

4.2 Carbon Monoxide Control Measures 4-1 

4.2.1 On-Road Mobile Sources 4-1 

 4.2.1.1 Cleaner Burning Gasoline 4-2 

 4.2.1.2 Transportation Control Measures / Travel Demand 

 Management 4-4 

 4.2.1.3 Technician Training and Certification 4-7

 4.2.1.4 Alternative Fuels Program 4-8 

4.3 Off-Road Mobile Sources 4-10 

4.4 Stationary Point and Area Sources 4-11 

 4.5 Previously Adopted Control Measures 4-11 

4.6 Summary of Primary Carbon Monoxide Control Measures 4-12 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN ii 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN iii 

Table of Contents - Continued

CHAPTER FIVE: AIR QUALITY MODELING 

5.1 Introduction 5-1 

5.2 Base Case Scenario Modeling 5-2 

5.3 Carbon Monoxide Episode Selection and Design Value 5-2 

5.4 Assessment of UAM Model Performance 5-5 

CHAPTER SIX: DEMONSTRATION OF ATTAINMENT 

6.1 Introduction 6-1 

6.2 2000 Base Year (No Action Scenario) Projections 6-1 

6.3 UAM Attainment Demonstration 6-4 

6.4 CAL3QHC Roadway Intersection Modeling 6-5 

6.5 Micro-Scale Analysis for Airports 6-7 

CHAPTER SEVEN: ADDITIONAL REQUIREMENTS OF THE 1990 CAAA 

7.1 Introduction 7-1 

7.2 VMT Tracking Programs 7-1 

 7.2.1 VMT Projections 7-1 

 7.2.2 Contingency Measures 7-3 

 7.2.3 Annual VMT Tracking 7-5 

7.3 Other Control Measures 7-5 

 

CHAPTER EIGHT: IMPLEMENTATION AND MONITORING 

8.1 Implementation 8-1 

8.2 SIP Implementation, Monitoring and Reporting 8-2 

8.3 Maintenance 8-2 

8.4 Mobile Sources Emissions Budget 8-3 

8.5 Additional Commitments to Insure Conformity 8-5 

REFERENCES R-1 

APPENDIX A: EMISSION INVENTORY 

APPENDIX B: TRANSPORTATION DOCUMENTATION 

APPENDIX C: MODELING DOCUMENTATION 

APPENDIX D: REGULATIONS AND POLICIES 

APPENDIX E: SUPPLEMENTAL TECHNICAL SUPPORT DOCUMENTATION 
Glossary of Acronyms

ADT Average Daily Trips 

AQD Air Quality Division 

CAAA Clean Air Act Amendment 

CAL3QHC Microscale Dispersion Model (based on California Line Source 

 Model) 

CO Carbon Monoxide 

DCP Department of Comprehensive Planning 

DTIM Direct Travel Impact Model 

EPA Environmental Protection Agency

FRM Federal Reference Method 

I/M Inspection and Maintenance 

LVACTS Las Vegas Area Computer Traffic System 

NAAQS National Ambient Air Quality Standards 

NAMS National Air Monitoring Station 

PPM Parts Per Million 

RTC Regional Transportation Commission 

SLAMS State and Local Air Monitoring Station 

TCM Transportation Control Measure 

TDM Transportation Demand Management 

TIP Transportation Improvement Program 

RTP Regional Transportation Plan 

UAM Urban Airshed Model 

________________________________________________________________ 

Carbon Monoxide State Implementation Plan iv 
________________________________________________________________ 

Carbon Monoxide State Implementation Plan v 

Glossary of Acronyms - Continued

VMT Vehicle Miles Traveled 

 

TRANPLAN Network based travel Demand Model which Estimates Vehicle 

 Miles Traveled 

MOBILE5a/5b Revised EPA Vehicle Emission Factor Model 
List of Tables 

Table 2-1 Las Vegas Valley Monitoring Sites Descriptions................................................... 2-3 

Table 3-1 Demographic Data Used in Developing Emissions Inventories and 

 to Project Activity Levels for Non-attainment Area ................................................ 3-1 

Table 3-2 1996 Carbon Monoxide Emission Summary-Average Daily CO 

 Season Emission .................................................................................................. 3-3 

Table 4-1 Recommended Carbon Monoxide Control Measures to Reduce On- 

 Road Mobile Source Emissions ............................................................................ 4-2 

Table 4-2 Acceptance Criteria for “CBG” as a Carbon Monoxide Emissions 

 Control Measure ................................................................................................... 4-4 

Table 4-3 Acceptance Criteria for TCM/TDM as a Carbon Monoxide Emissions 

 Control Measure ................................................................................................... 4-6 

Table 4-4 Acceptance Criteria for Technician Training and Certification as a 

 Carbon Monoxide Control Measure ..................................................................... 4-8 

Table 4-5 Acceptance Criteria for Alternative Fuels as a CO Emissions Control 

 Measure.............................................................................................................. 4-10 

Table 4-6 Previously Adopted Enforceable Carbon Monoxide Control Measures .............. 4-12 

Table 4-7 Primary Control Measures, Benefits, and Cost Effectiveness............................. 4-13 

Table 5-1 List of Highest 10 CO Episodes Based on Peak 1- and 8-hour 

 Average CO Concentrations. Values Reported for East Charleston 

 (EC) and Sunrise Acres (SA) ................................................................................. 5-3 

Table 5-2 Model Performance Statistics for December 8-9, 1996 Comparing 

 Scaled UAM 8-hour Average CO Concentrations with Measurements 

 from all Sites Operated During the Field Study ..................................................... 5-5 

Table 6-1 1996 & 2000 Base Years Carbon Monoxide Modeling Emissions for 

 The Las Vegas Valley Nonattainment Area .......................................................... 6-3 

Table 6-2 Proposed Enforceable CO Control Measures....................................................... 6-5 

Table 6-3 UAM Maximum Predicted Ambient Concentrations for the Various 

 Scenarios .............................................................................................................. 6-5 

________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN vi 
________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN vii 

List of Tables – Continued

Table 6-4 Maximum Predicted 8-Hour CO Concentrations for Hot Spot 

 Intersections.......................................................................................................... 6-7 

Table 6-5 Maximum 8-hour Carbon Monoxide Concentrations (ppm) From 

 County Operated Airports for Four Modeling Years (Base Case 

 Estimates Assume no Additional Controls on Motor Vehicles) ................................... 6-9 

Table 7-1 Average Daily VMT Estimates and Forecasts by Functional Category................. 7-2 

Table 7-2 Contingency Measures ......................................................................................... 7-3

Table 7-3 Insurance Control Measures ................................................................................ 7-5 

Table 8-1 Control Measure Implementation Status............................................................... 8-1 

Table 8-2 VMT Estimates for Monitoring and Maintenance .................................................. 8-3 

Table 8-3 Las Vegas Valley Peak Season Emission Budgets by Source 

 Category ............................................................................................................... 8-4 
List of Figures 

Fig. 1-1 Las Vegas Valley Carbon Monoxide Non-attainment Area. 1-5 

Fig. 1-2 Three Dimensional Perspective of the Las Vegas Valley Modeling 

 Domain as Viewed from the Southwest. 1-6 

Fig. 1-3 Las Vegas Carbon Monoxide Wind Drainage Patterns. 1-7 

Fig. 2-1 Las Vegas Valley Carbon Monoxide Monitoring Sites Locations. 2-4 

Fig. 2-2 Carbon Monoxide Air Quality Trends - Unhealthy Days. 2-6 

Fig. 2-3 Carbon Monoxide Air Quality Trends - Exceedence Days. 2-7 

Fig. 3-1 1996 Annual CO Emissions by Source Category. 3-4 

Fig. 5-1 Analysis of Maximum 8-hour CO Concentration Measurements (ppm) 

 in Central Las Vegas on December 8-9, 1996. 5-4 

Fig. 5-2 Graphs Comparing Observed CO Concentrations and UAM Predicted 

 Concentrations at a Corresponding Site. 5-6 

Fig. 6-1 CAL3QHC Intersection Location Map. 6-6

________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN viii 
Chapter One - Plan Introduction

1.1 INTRODUCTION 

1.2 PROBLEM STATEMENT 

1.3 PHYSICAL DESCRIPTION 

1.4 CLIMATOLOGICAL SETTING 

1.5 FOCUS OF THIS PLAN
1.1 INTRODUCTION 

The 1990 Clean Air Act Amendments (CAAA) redefined the national air pollution

abatement framework and established ambitious policies to carry out air quality

planning and control activities. The requirements mandated by the CAAA affect 

the Las Vegas Valley in many ways. Two National Ambient Air Quality 

Standards (NAAQS) have been established for carbon monoxide. The 1-hour 

standard has a maximum allowable concentration of 35 parts per million (ppm). 

The 8-hour standard is a maximum average of 9 ppm over an 8-hour period.

Areas that violate one or both of the ambient standards more than two times in a 

two-year period are classified as non-attainment areas for carbon monoxide.

Previously, portions of the Valley violated the NAAQS for carbon monoxide (CO) 

during the winter months. The number and severity of the CO violations caused 

the U.S. Environmental Protection Agency (EPA) to designate the Valley as a

Moderate nonattaiment area on November 15, 1990. Moderate nonattainment 

areas were required to implement emission control measures as “expeditiously

as practicable” in order to attain the CO NAAQS by December 31, 1995. The 

Clean Air Act requires that moderate nonattainment areas implement the 

following controls: 

1. An oxygenated gasoline program during the winter months that require 

gasoline to contain no less than 2.7% oxygen by weight; 

2. An enhanced vehicle inspection and maintenance program meeting the Clean 

Air Act’s criteria; 

3. Forecasts of vehicle miles traveled (VMT) in the region, procedures for annual

updates and reports attesting to the accuracy of the forecasts, and estimates

of actual VMT based on traffic counts on area roadways; 

4. Contingency measures that must be implemented if actual VMT exceeds 

forecasted VMT or if the area fails to attain the standard by the applicable date; 

and 

5. Transportation control measures necessary to demonstrate attainment of the 

standard (section 187(b)(2)). 

Clark County implemented the above listed controls and made great strides

towards attaining the NAAQS for carbon monoxide but, due to the phenomenal 

growth the valley experienced during this decade, it fell short of meeting the 

NAAQS by the applicable date of December 31, 1995. 

Improved carbon monoxide levels, attributed to the implementation of the 

aforementioned control measures, resulted in Clark County being granted a oneyear extension to demonstrate compliance with the NAAQS. However, the Las 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-1 
Vegas Valley was not successful in achieving compliance by December 31, 

1996. The CAAA requires that the area be “bumped“ up, or be reclassified as a 

“serious” nonattainment for carbon monoxide. 

The notice of violation reclassifying the area was published in the Federal 

Register on November 3rd, 1997. A deadline of May 1999 (18 months from the 

notice publication date) is set by the CAAA for submission of a control strategy 

implementation plan demonstrating attainment of the NAAQS for Carbon 

Monoxide by December 31, 2000. This document represents such a plan in 

fulfillment of sections 107 and 110 of the CAAA. 

1.2 PROBLEM STATEMENT 

The Las Vegas Valley has been reclassified as a serious nonattainment area for 

CO air pollution after failing to attain the standard by the extended CAAA 

deadline of December 31, 1996. Although the Valley has never exceeded the 1-

hour standard, the 8-hour standard was being exceeded at least once per year

on a seasonal basis. During the winter months local inversions stagnate air

masses and trap pollutants. The overnight buildup of pollutants causes

exceedance violations of the CO 8-hour air quality standard in a limited area 

surrounding the Sunrise Acres monitoring station. 

While the East Charleston station recorded 10 exceedances during the 1991-

1992 winter season, the number of exceedances was reduced to 1 in 1995, 3 in 

1996, 1 in 1997, and 2 in 1998. This downtrend is the direct result of the 

implementation of CO control measures. The East Charleston (recently 

relocated and re-named Sunrise Acres) monitoring site is adjacent to converging 

major transportation corridors named the “Five Points” where three state 

highways intersect. Additionally, the site is located in a topographic bowl where 

air pollution often collects. In the 1996 season, the highest 8-hour average CO

concentration also occurred in the “Five Points” area and measured 10.2 parts 

per million. 

As mentioned above, the Las Vegas Valley is required to attain the standard by

December 31, 2000. The CAAA requires serious non-attainment areas to meet

all the requirements for moderate areas listed previously, in addition to

implementing the following measures: 

1. Gasoline sold during winter months must contain a level of oxygen as

necessary, in combination with other measures, to provide for attainment of the 

standard. EPA may waive this requirement if the area demonstrates that the 

revision is not necessary to provide for attainment of the CO standard by the 

applicable attainment date and maintenance of the standard thereafter. 

2. Mandatory employer-based travel reduction program for employers of 100 or

more people that requires each employer to increase average vehicle 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-2 
occupancy for commute trips by at least 25% over the regional average.

However, this requirement can be avoided if the area can show that such a 

program is not needed to demonstrate attainment of the standard or that a 

comparable emission reduction is achieved by other measures. 

3. An economic incentive program containing fees and marketable permits if 

emission reduction milestones are not met by December 31, 2000. 

4. Beginning in 1997, regional transportation plans must specifically describe the 

transportation system for future horizon years. This requires the Regional 

Transportation Commission Board to approve specific projects and programs 

for 2000, 2010, 2020. 

1.3 PHYSICAL DESCRIPTION 

The Las Vegas Valley Nonattainment Area, which coincides, with Hydrographic

Basin 212, is illustrated in Figure 1-1. This area includes the City of Las Vegas, 

the City of North Las Vegas, and the City of Henderson. The remainder

constitutes unincorporated areas of Clark County. The Las Vegas Valley airshed 

extends in a northwest-southeast direction bounded by the Spring Mountains to 

the west; the Pintwater, Desert, Sheep, and Las Vegas Mountains to the north; 

and Frenchman Mountain to the east. The McCullough Range and Big Spring 

Range close the airshed to the south. The airshed covers approximately 500 

square miles. The Valley drains toward the south and then easterly through Las 

Vegas Wash to Lake Mead. The upper boundaries of the alluvial apron occur at 

approximately 4500 feet and are marked by a noticeable change in slope. The 

lower boundaries of the apron are less well defined due to massive 

sedimentation on the valley floor, but occur at an average elevation of 

approximately 2500 feet. The basin lowland levels of the Las Vegas Valley

range from 1800 to 2500 feet. Figure 1-2 provides a three dimensional 

topographical perspective of the Las Vegas Valley modeling domain. 

1.4 CLIMATOLOGICAL SETTING 

The Las Vegas Valley is situated on the edge of the Mojave Desert and 

experiences an arid climate typical of the southern Mojave Desert. Due to the 

"rain shadow" effect of the Sierra Nevada Range and Spring Mountains to the 

west, moisture associated with storms originating in the Pacific Ocean rarely

reaches the Valley. Dry air masses move over the valley resulting in clear to 

partly cloudy skies with 85 percent sunshine for an average year. 

Temperatures range from an average daily maximum in July of approximately

104 degrees to an average daily maximum in January of approximately 56 

degrees. Average daily minimums range from 33 degrees in January to 75 

degrees in July. Winters are generally mild and summers are hot. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-3 
Surface meteorology in the Las Vegas Valley is generally characterized by

prevailing southwesterly winds with monthly average wind speeds ranging from 7 

to 11 miles per hour. Lower wind speeds are prevalent during the winter months 

with a windy season throughout much of the spring. Winds in excess of 40 miles 

per hour are infrequent. During these events, periods of wind gusts, blowing 

sand and dust are prevalent. In addition to prevailing winds, a pattern of local 

winds, generated by local topography and temperature, also affect the Valley.

During the day, as the air mass is heated, wind directions are generally upslope 

and in a westerly gradient. At night, the wind direction is reversed and cool air 

drawn from the higher elevations drains to the lower Valley. Figure 1-3 displays

the evening wind drainage patterns of the Las Vegas Valley. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-4 
FIGURE 1-1 

(.......) The dotted line around the non-attainment area (Basin 212) represents a 25-mile zone to 

consider sources that may contribute CO emissions.

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-5 
FIGURE 1-2 

THREE-DIMENSIONAL PERSPECTIVE OF THE LAS VEGAS VALLEY 

MODELING DOMAIN AS VIEWED FROM THE SOUTHWEST

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-6 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-7 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 1-8 

1.5 FOCUS OF THIS PLAN 

The remainder of this document consists of seven chapters, each addressing a 

specific topic. These chapters are briefly summarized below: 

Chapter 2, "Carbon Monoxide Monitoring Network and Trends in Air Quality," 

provides information on the monitoring network and CO air quality trends. 

Chapter 3, "Emission Inventory Summary," presents the 1996 base year 

emissions inventory for stationary, area, and mobile sources (on- and off-road) 

as required under the 1990 CAAA. 

Chapter 4, "Control Measures," introduces and describes the control strategies, 

which will result in reducing CO emissions and lead to attainment status. 

Chapter 5, "Air Quality Modeling," describes the modeling process for the 1996 

base case utilizing the Urban Airshed Model including the preparation of inputs 

and the model’s performance. 

Chapter 6, "Demonstration of Attainment," describes the modeling analysis 

demonstrating attainment of the NAAQS and summarizes the CO concentrations 

with recommended control measures. 

Chapter 7, "Additional Requirements of the 1990 Clean Air Act Amendments," 

presents forecasts of vehicle miles traveled (VMT) and identifies the agencies 

responsible for preparing VMT tracking reports. Contingency measures which 

will be enacted if actual VMT counts exceed projected VMT are also discussed. 

Chapter 8, “SIP Commitments / Implementation”, discusses the implementation 

of control measures, monitoring progress, emissions budget, maintaining 

attainment once it is achieved and concludes with a brief discussion on 

areas/issues to receive additional study. 

The Appendices are divided into four sections. Appendix A contains the “1996 

base year Carbon Monoxide Emission Inventory for the Las Vegas Valley 

Nonattainment Area”. Appendix B consists of the “Transportation Control 

Measure Analysis Report” and associated data. Appendix C accommodates 

modeling documentation including the attainment demonstration, emission 

reduction calculations and associated costs. Appendix D contains regulations 

and policies associated with the control measures documenting the enforceability 

of these control measures. Appendix E consists of additional technical support 

documentation for the control measures and supplemental modeling analyses 

that support the future year emission budgets.
Chapter Two- Monitoring Network and Trends in 

Air Quality

2.1 INTRODUCTION 

2.2 BACKGROUND 

2.3 MONITORING NETWORK 

2.4 TRENDS IN CARBON MONOXIDE AIR QUALITY
2.1 INTRODUCTION 

This chapter provides some background about carbon monoxide (CO) air 

pollution and a brief summary of the Las Vegas Valley CO monitoring network as

of July 1999. In addition, this chapter provides a discussion of the trends in air

quality for CO over the past several years. The CO sampling program indicates

that air quality is improving. The reasons for these positive developments in 

recent years are briefly discussed. 

2.2 BACKGROUND 

Carbon monoxide occurs in the atmosphere as the result of incomplete 

combustion of fuels. In Las Vegas, as in other urban areas, motor vehicles are 

the major source of CO emissions, comprising approximately 88 percent of total 

daily emissions and even more in the late afternoon and evening hours when 

exceedences of the standard are usually recorded. For more details on the 

sources of CO emissions and a breakdown of contribution by category refer to 

Chapter 3 of this document. 

Carbon monoxide is a colorless, odorless, and tasteless gas. CO enters the 

body through the lungs, where it is absorbed by the bloodstream and then 

combines with hemoglobin in the red blood cells. Hemoglobin is the compound 

in the red blood cells that normally picks up oxygen from the lungs and carries it 

to the tissues. When CO binds with hemoglobin, it forms a compound called 

carboxyhemoglobin (COHb). COHb diminishes the blood’s capacity to carry 

oxygen. Hemoglobin has more affinity for CO than oxygen. Furthermore, once 

attached it does not dissociate from the hemoglobin as readily as oxygen does at 

the tissue level. As a result, with continued exposure to CO, COHb levels will 

continue to increase in the bloodstream and the amount of oxygen being 

distributed throughout the body is reduced. 

At greatest risk from CO exposure are individuals with cardiovascular disease, 

chronic obstructive pulmonary disease, pregnant women, and children. Even 

healthy individuals can experience adverse effects from CO exposure, such as 

reduced ability to concentrate. CO exposures in higher altitude areas present a

greater risk because of the inherently low-oxygen atmosphere. 

Blood laden with CO can weaken heart contractions, lowering the blood volume 

being distributed to the body. A life-threatening situation exists in-patients with 

heart disease, which are unable to compensate for the loss of oxygen. The 

millions of people in the U.S. that have a condition known as angina pectoris 

(characterized by brief, spasmodic attacks of chest pain due to reduced blood 

flow to heart muscles) may also be more sensitive to exposure to CO. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-1 
CO also affects the central nervous system by depriving it of oxygen. Studies of 

automobile drivers reveal that exposure to CO can impair a driver’s judgement 

and ability to respond rapidly to emergency traffic situations. 

In order to protect public health and the environment, the U.S. Environmental 

Protection Agency (EPA) established specific standards for CO in 1971. The 

most stringent standard of 9 parts-per-million (PPM) is averaged over a rolling 8-

hour period, while the maximum allowable hourly concentration is 35 PPM. EPA 

is mandated by the Clean Air Act to review the standard every 5 years. EPA has

periodically reviewed the CO standards and has made no changes to the current 

standards. 

2.3 MONITORING NETWORK 

The U.S. EPA has established ambient air quality monitoring requirements and

standards for State and Local Air Monitoring Stations (SLAMS) and for National 

Air Monitoring Stations (NAMS). These requirements and standards provide for 

operating schedules, data quality assurance, and for the design and siting of CO 

samplers. Table 2-1 below provides some details about the monitoring sites. 

Each of the air quality monitoring stations utilizes a Dasibi Carbon Monoxide 

Analyzer (Model 3003) which employs the Gas Filter Correlation technique. The 

monitoring schedule is continuous. 

The Carbon Monoxide air-monitoring network in the Las Vegas Valley has 

evolved into a system of 15 monitoring sites (see Table 2-1). There are 7

SLAMS sites, 4 NAMS sites, and 4 special purpose monitoring sites. The Air 

Quality Division (AQD) of the Clark County Health District operates and 

administers the air-monitoring program. The system is governed by a set of 

quality assurance and quality control procedures approved by the EPA and is

subject to periodic performance audits by the EPA. Quarterly air quality 

monitoring reports are being prepared and submitted to the EPA. Carbon

monoxide sampling locations are identified in Figure 2-1 below. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-2 
TABLE 2-1 

LAS VEGAS VALLEY CARBON MONOXIDE MONITORING SITE DESCRIPTIONS 

________________________________________________________________________________________________

________________________________________________________________________________________________

SITE NAME ADDRESS TYPE* ELEVATION

Boulder City 1005 Industrial & US95 APCD 2391'

City Center 559 N. 7th Street NAMS 2020'

Craig Road 4701 Mitchell Street SLAMS 1919'

Crestwood 1300 Pauline Way NAMS 1958'

East Flamingo 210 E. Flamingo SLAMS 2017'

East Sahara 4001 E. Sahara Ave. SLAMS 1692'

Health District 625 Shadow Lane SLAMS 1935'

Green Valley 248 Arroyo Grande APCD 2010'

S.East Valley 545 Lake Mead Dr. SLAMS 1870'

Winterwood 5483 Club House Dr. SLAMS 1708'

Paul Meyer 4525 New Forest Dr. APCD 2309'

Pittman 1137 Boulder Highway APCD 1699'

S. L.V. Blvd 3799 South L.V. Blvd. NAMS 2079'

Sunrise Acres 2501 S. Sunrise Ave. NAMS 1889'

J. D. Smith 1301B East Tonopah SLAMS 1775'

_______________________________________________________________________________________________

* Notes: AQD = Air Quality Division Special Purpose (monitoring) Location 

Source: Clark County Health District (July, 1998) 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-3 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-4 
2.4 TRENDS IN CARBON MONOXIDE AIR QUALITY 

An exceedence of the 1-hour CO national standard (35-PPM) has never been 

recorded within the Las Vegas Valley. Exceedence events are limited to the 8-

hour national standard (9-PPM). During the past several years, the Las Vegas

Valley has experienced a substantial improvement in CO air quality. On an 

annual basis, there has been a trend towards a reduction in the number of 

exceedence events and a reduction in the intensity of CO concentrations. 

Figures 2-2 & 2-3 below illustrate this improving CO picture graphically. 

Apart from a winter season with fewer inversions, annual reductions in 

exceedence events and CO concentrations are attributed to the following: 

1) Improved motor vehicle emission control technology and the continued 

 displacement of older and poorly maintained vehicles; 

2) The wintertime oxygenated gasoline program; 

3) Reduced Reid Vapor Pressure (RVP) in gasoline; 

4) Requirements for annual vehicle smog tests for motor vehicles, including 

 medium and heavy duty gasoline vehicles; 

5) The computerized traffic signal management program; and 

6) The use of the east leg freeway and other roadway improvements. 

During 1997 and 1998, the Las Vegas Valley experienced only four unhealthful 

days and three exceedence days. In 1999, there were no unhealthful or

exceedence days recorded in the Valley. These unhealthful and exceedence 

days were recorded at the Sunrise Acres (old East Charleston) station. None of 

the other monitoring stations reported any unhealthful episodes or exceedences

during these same periods. A day is classified as “unhealthful” when monitoring 

data indicate that carbon monoxide levels are above 100 on the pollution 

standard index (PSI). The PSI, also known as the air quality index (AQI), was 

developed by the EPA in 1976 to provide accurate, timely, and easily

understandable information about daily levels of air pollution. A PSI level of 100 

was set to equal the national ambient air quality standard (NAAQS) for a given 

regulated pollutant. The PSI scale is divided into the following ranges, which are 

in turn attributed to the following health levels: 

 

 0 - 50 Good 

 51 - 100 Moderate 

 101 - 200 Unhealthful 

201 - 300 Very unhealthful 

 ≥ 300 Hazardous

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-5 
In the case of the Las Vegas Valley’s air monitoring system, operated by the

AQD, a PSI of 113 (9.5 PPM for an 8-hour average) or above would translate into 

an exceedence of the NAAQS.

FIGURE 2-2 

LAS VEGAS VALLEY 

CARBON MONOXIDE AIR QUALITY TRENDS - UNHEALTHY DAYS

32

41

38

34

48

39

24

27

34

17

14

5

8 8 7

4

1

3

0

0

10

20

30

40

50

60

1981198219831984198519861987198819891990199119921993199419951996199719981999

Year

Number of Days

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-6 
FIGURE 2-3 

LAS VEGAS VALLEY 

CARBON MONOXIDE AIR QUALITY TRENDS - EXCEEDENCE DAYS

27

32

33

24

41

32

18

22

27

13

6

2

3

4

1

3

1

2

0

0

5

10

15

20

25

30

35

40

45

1981198219831984198519861987198819891990199119921993199419951996199719981999

Year

Number of Days

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 2-7 
Chapter Three - Emissions Inventory Summary

3.1 INTRODUCTION 

3.2 EMISSIONS SUMMARY 

3.3 TOTAL ANNUAL EMISSIONS 
3.1 INTRODUCTION 

The CAAA require that all nonattainment areas prepare a base year inventory

that is comprehensive, accurate, and current with respect to actual emissions in 

the area [Section 182(a)(1)]. The peak season and modeling inventories are 

based on this inventory. This section summarizes the 1996 base year CO 

inventory for the Las Vegas Valley Nonattainment Area. The inventory 

addresses CO emissions from the following four major type categories: stationary

point sources, area sources, on-road mobile sources, and non-road mobile 

sources. The intent of this section is to provide a brief overview of the source

categories and the associated methodologies employed to estimate emissions.

More detailed information pertaining to the inventory can be found in the “Carbon 

Monoxide Emission Inventory for the Las Vegas Valley Nonattainment Area,”

contained in Appendix A. 

The Clark County Department of Comprehensive Planning (DCP) is the agency

responsible for preparing and submitting the Clark County, Las Vegas Valley 

Nonattainment Area 1996 base year CO emissions inventory. The DCP is also 

responsible for coordinating and supervising the completion of each part of the 

inventory. Several other local agencies contributed information necessary for

preparing emissions estimates. These agencies include the AQD, Clark County 

Regional Transportation Commission (RTC), Clark County Department of 

Aviation, and the Clark County Fire Department. Additional information sources

included the Nevada Department of Transportation, U.S. Forest Service, and 

Southwest Gas Corporation. 

The point source inventory was prepared primarily from a mail survey by the 

AQD. Survey results were supplemented by information obtained through 

personal contacts during compliance inspections. VMT data necessary to 

calculate on-road mobile source emissions was provided by the RTC. The DCP 

ran the MOBILE5b model to determine vehicle emission factors from on-road 

mobile sources. Table 3-1 below contains demographic information for Clark 

County. 

Table 3-1 

Demographic Data Used in Developing Emission Inventories and to Project Activity 

Levels for Non-attainment Area*

January Population Employment V M T

1996 1,037,844 493,213 22,469,020

2000 1,269,600 609,400 24,929,485

2010 1,790,700 859,500 38,022,330

2020 2,406,500 1,115,100 57,492,333

* Data is based on Regional Transportation Commission 1997 Estimates / Projections

__________________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 3-1
3.2 EMISSIONS SUMMARY 

The results of the Las Vegas Valley 1996 base year CO emissions inventory for 

stationary point and area sources, on-road mobile sources, and non-road mobile 

sources categories are tabulated in this section. The biogenics category has 

been omitted, as it is not applicable to carbon monoxide emissions. Table 3-2 

below contains a detailed listing of average daily, CO season emissions by 

source category. Large stationary sources at the periphery of the nonattainment 

area (State Hydrographic Basin No. 212) have also been included in the 

inventory.

__________________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 3-2
TABLE 3-2 

1996 CARBON MONOXIDE EMISSION SUMMARY 

-Average Daily CO Season EmissionSOURCE CATEGORIES Emissions Emission

(Tons/Day) (Percent)

STATIONARY POINT SOURCES

Titanium Metals 2.92 0.61

Kerr McGee-BMI 0.24 0.05

Chemical Lime Co. Apex 0.82 0.17

Bonanza Materials 0.28 0.06

James Hardie Gypsum 0.55 0.11

Southern Nevada Paving 0.55 0.11

Pabco Cogeneration/NCA 2 0.55 0.11

Georgia Pacific@Apex/NCA 1 0.62 0.13

Point Source Total 6.53 1.36

AREA SOURCES

Small Stationary 2.7 0.56

Boiler Emissions 0.38 0.08

Fireplaces 2.12 0.44

Structural Fires 0.64 0.13

Vehicular Fires 0.05 0.01

Brush Fires 1.26 0.26

Residential Natural Gas 0.31 0.06

Commercial Natural Gas 0.09 0.02

Industrial Natural Gas 0.32 0.07

Electrical Utility Generation 0.56 0.12

Cigarette Smoking 0.04 0.01

Area Source Total 8.47 1.8

NON-ROAD MOBILE SOURCES

County Airports 36.4 7.6

Nellis Air Force Base 2.86 0.6

Locomotive Emissions 0.23 0.05

Lawn & Garden Equipment 3.57 0.75

Construction Equipment 9.77 2.04

MC & Recreation Equipment 5.9 1.23

Non-Road Total 58.73 12.3

ON-ROAD MOBILE SOURCE 405.4 84.61

GRAND TOTAL 479.13 100

__________________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 3-3
3.3 TOTAL ANNUAL EMISSIONS 

Total average annual CO emissions associated with the Las Vegas Valley 

Nonattainment Area for the 1996 base year are 479.1 tons per day. Figure 3-1 

depicts the relative magnitude of annual contribution by each source category 

and indicates that the percent contributions of emissions by source category are 

consistent on both a seasonal and annual basis.

Figure 3-1

1996 Annual CO Emissions by Source

Area Sources

2%

Non-Road Sources

12%

Stationary Sources

1%

On Road Mobile

Sources

85%

__________________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 3-4
Chapter Four – Control Measures 

4.1 INTRODUCTION 

4.2 CARBON MONOXIDE CONTROL MEASURES 

 4.2.1 On-Road Mobile Sources 

 4.2.1.1 Cleaner Burning Gasoline 

4.2.1.2 Transportation Control Measures / Trip Demand 

 Management (TCM/TDM) 

 4.2.1.3 Technician Training and Certification 

4.2.1.4 Alternative Fuels Program 

4.3 OFF-ROAD MOBILE SOURCES 

4.4 STATIONARY POINT AND AREA SOURCES 

4.5 PREVIOUSLY ADOPTED CONTROL MEASURES 

4.6 SUMMARY OF PRIMARY CARBON MONOXIDE CONTROL 

 MEASURES 
4.1 INTRODUCTION 

About 86 percent of the CO emissions in the Las Vegas Valley in 1996 were 

produced by on-road motor vehicles. Non-road mobile sources contributed about

11 percent. Stationary, point, and area sources accounted for the remaining 3 

percent of the total emissions. This chapter presents the control measures being 

implemented in order to attain the CO NAAQS. The identified control measures

are those which are considered to offer the most potential for reducing carbon 

monoxide emissions. Particular attention is given to control measures for onroad motor vehicles. The Lima & Associates report (Appendix B, Section 1)

contains additional information and calculations on the costs and emission 

reductions of some of these control measures. This chapter concludes with a 

discussion on off-road mobile sources, area sources, and stationary sources 

control measures contained in the 1995 Carbon Monoxide Air Quality

Implementation Plan for the Las Vegas Valley Nonattainment Area. These 

control measures have previously been implemented. 

4.2 CARBON MONOXIDE CONTROL MEASURES 

Regulations and resolutions in support of the control measures necessary for 

attainment have already been adopted and became effective at the end of 1999 

(Appendix D). Control measures and programs from previous plans which are 

listed later in this chapter, serve as the foundation upon which additional 

measures will be added to show attainment of the standard. When fully

implemented by the end of the year 2000, the proposed control measures 

discussed below, along with all the control measures implemented to date, will 

reduce CO emissions from on-road motor vehicles by over 22 percent from 1996 

levels. The control measures outlined in this section are sufficient to ensure 

attainment and maintenance of the CO NAAQS by the designated attainment

date, and target the largest contributing source category, mobile sources.

Contingency measures, which will be implemented if VMT estimates are 

exceeded or if needed to attain and/or maintain the federal standard, are 

addressed in Chapter 7 of this document. Table 4-1 below summarizes the 

three primary control measures relied upon in demonstrating attainment with the 

CO NAAQS. Each control measure is listed along with its estimated reduction 

benefit; adoption date; and the agency responsible for its implementation,

enforcement, and monitoring. 

4.2.1 On-Road Mobile Sources 

On-road motor vehicles include passenger cars, light-duty trucks, medium-duty 

vehicles, heavy-duty vehicles, and motorcycles. Proposed strategies for 

reducing CO emissions from on-road motor vehicles include Cleaner Burning 

Gasoline (CBG) for the winter season, some voluntary Traffic Control Measures / 

Trip Demand Management (TCM/TDM) programs, Vehicle Inspection 

Maintenance Program Technician Training and Certification and an Alternative 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-1 
Fuels Program (AFP) for government fleets. Table 4-1 identifies these federally 

enforceable and voluntary mobile source CO control measures and their 

anticipated emission reductions by the end of the year 2000. The remainder of 

this chapter summarizes these control measures, including their effectiveness 

and implementation. 

TABLE 4-1 

RECOMMENDED CARBON MONOXIDE CONTROL

MEASURES TO REDUCE ON-ROAD MOBILE SOURCE EMISSIONS

Control Measure 

Year 2000 

Emission 

Reduction 

Adoption Date Responsible Agency 

Clean Burning Gasoline 9.8% 1999 Health District 

Voluntary Transportation Control 

Measures / Transportation 

Demand Management 

0.08% 1999/Ongoing RTC 

Technician Training and 

Certification 2.95% 1988 DMV&PS 

Alternative Fuels Program for 

Government Fleets 0.12% 1991/Ongoing NDEP/Govt. Entities

Combined Effect of Controls 12.2% 

4.2.1.1 Cleaner Burning Gasoline (CBG) 

The Clark County District Board of Health is the governing board responsible for 

promulgating regulations for a Cleaner Burning Gasoline program and the Clark 

County Health District Air Quality Division (AQD) is the agency responsible for 

administering their implementation. This authority is vested in the Health District

through Chapter 445B of the Nevada Revised Statutes (NRS 445B). The AQD is 

also responsible for administering the existing oxygenated fuels program. 

CBG is a low sulfur and low aromatic fuel. Sulfur and aromatics in fuel adhere to 

manifolds, piping, and catalytic converters reducing the efficiency of air pollution 

control devices. It has been shown that reducing sulfur and aromatic levels in 

gasolines increases catalytic converter effectivness, resulting in lower CO, as 

well as other air emissions. On April 22, 1999, the Clark County District Board of

Health adopted section 54 of the Air Pollution Control Regulations to implement 

the CBG program starting November 1, 1999 to March 31, 2000 and each such 

winter season thereafter. Under this program compliance can be achieved by

one of two methods: a flat limit of 40 ppm by weight for sulfur and 25 percent for 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-2 
aromatics; or a maximum sulfur limit of 80 ppm by weight and 30 percent for

aromatics with averages not exceeding 30 ppm and 22 percent respectively. 

Adoption of the aforementioned limits will lower CO emissions from gasoline 

powered motor vehicles in the Las Vegas Valley by approximately 31.9 tons per 

day, or by 9.8% above and beyond the benefits provided by existing control

measures (RVP, 3.5% oxygenated fuel, etc.). The current State and local 

regulations for Reid Vapor Pressure of 9 psi and oxygen content of 3.5% by

weight will not change. It is estimated that consumers would pay between 2 and 

5 cents more per gallon for this improvement for a total annual cost to the public

of about 15 million dollars. The cost effectiveness for this much needed CO

emission reduction will average about $1,225 per ton of CO reduced. CBG can 

satisfy all eight acceptance criteria constituting applicable State and Federal 

requirements for the adoption of a fuel control measure. These criteria include 

the following: practicality, reasonableness, reliability, its necessity for attainment,

effectiveness, safety, cost effectiveness, and availability of technology. Table 4-2 

summarizes how the acceptance criteria are met for CBG as a CO emission 

control measure. 

The AQD is also responsible for monitoring and enforcing the Cleaner Burning 

Gasoline program. Nearly all gasoline delivered to the Valley is refined in 

Southern California. Compliance inspections on CBG primarily targets the 

refiners and shippers. The Health District has contracted with the California Air

Resources Board (CARB) to sample and track the wintertime clean burning 

gasoline shipments at the refinery. CARB has had this monitoring and tracking 

program in place for many years to insure compliance with their own state fuel 

requirements. Additionally, the Nevada Department of Agriculture’s Bureau of 

Weights and Measures conducts random sampling at gasoline stations and 

informs the Health District when testing indicates non-compliance with the 

regulations. Annual reports summarizing the winter season gasoline programs 

will be provided to the EPA at the conclusion of the applicable time period.

Section 54 of the Air Pollution Control Regulations provides additional detailed 

information on testing, record keeping and enforcement of the Cleaner Burning 

Gasoline program. A copy of this regulation can be found in Appendix D, Section 

1, along with a report on the 1999 –2000 Wintertime Cleaner Burning Gasoline 

Program. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-3 
TABLE 4-2 

ACCEPTANCE CRITERIA FOR “CBG” AS A CO CONTROL MEASURE

ACCEPTANCE CRITERION HOW CRITERION IS MET 

Effectiveness EPA’s CO Complex Model estimates 

that emissions can be reduce by 9.8% 

or 31.9 tons per day. This makes CBG

an effective control measure. 

Safety The procedure for safe handling,

transporting and dispensing 

conventional gasoline will apply to this 

reformulated gasoline. 

Cost Effectiveness $1,225 per ton of CO reduced is within 

the acceptable range of other existing 

cost effective control measures. 

Availability of Technology Presently, the fuel is refined in the 

State of California at a rate of 38 million

gallons per day. Informal advice by

California Energy officials indicates that 

additional local demand here of 1.5 

million gallons per day will not 

jeopardize overall supply conditions. 

Practicality The common use of reformulated 

gasoline in several other states 

suggests that CBG is practical. 

Reasonableness The common use of reformulated 

gasoline in several other states 

suggests that CBG is reasonable.

Reliability Substantial emission testing by vehicle 

manufacturers and petroleum

marketers document reliability of CBG

as a CO control measure. 

Necessary for Attainment It is shown in Chapter 6 of this 

document that CBG is a necessary 

control measure for demonstrating 

attainment. 

4.2.1.2 Transportation Control Measures / Travel Demand Management 

(TCM/TDM)

The 1990 CAAA requires that consideration be given to the implementation of 

TCMs for the purposes of reducing motor vehicle emissions and offsetting growth 

in vehicle miles traveled (VMT). As a serious CO nonattainment area, the Las 

Vegas Valley is required to evaluate and implement (if practical) those TCMs 

referenced in Section 187(b)(2) referencing Section 182(d)(1)(A) and (B) with the 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-4 
focus of reducing carbon monoxide emissions. Section 108(f) of the CAAA also 

requires that plans evaluate and implement such measures as necessary to 

demonstrate attainment of the CO standard, in combination with other measures. 

The CAAA sections referenced above allow the Las Vegas Valley and other 

serious CO nonattainment areas to be exempt from the stated requirements if 

certain conditions are met. These sections contain language that is interpreted 

to mean that the SIP needs only to contain those TCMs that are necessary to 

demonstrate attainment. This section of the document contains the rationale for 

the selected TCMs, benefits and criteria for their selection. 

In developing this plan, a Carbon Monoxide Transportation Control Measure 

Analysis was conducted by Lima and Associates. A copy of this document is 

contained in Appendix B, Section 1. The intent of this study was to identify those 

transportation control measures that showed the greatest potential in reducing 

carbon monoxide emissions in the Valley. Based on this study’s findings, the 

following measures are being implemented as voluntary control measures: 

employer based commuter incentive programs, telecommuting and area wide 

ridesharing programs. 

According to EPAs policy on Voluntary Mobile Source Emission Reduction 

Programs (VMEPs), reflected in a memorandum dated October 24, 1997, from 

Richard D. Wilson, “ Voluntary mobile source measures have the potential to 

contribute, in a cost-effective manner, emission reductions needed for progress 

toward attainment and maintenance of the NAAQS.” Furthermore this guidance 

states, “EPA believes that SIP credit is appropriate for voluntary mobile source 

measures where we have confidence that the measures can achieve emission 

reductions.” Under this policy, credit for VMEPs are limited to 3% of the total 

projected future year emissions reductions required to attain the NAAQS. 

The VMEP control measures, consisting of employer based commuter incentive 

programs, telecommuting and an area wide ridesharing program, are being 

recommended for implementation by this plan. The Transportation Demand 

Management Division of the Clark County’s Regional Transportation Commission 

will be responsible for implementing, managing and monitoring this program. 

Through adoption of the TIP (FY 1998-2000), the implementation of TDM 

strategy is prioritized. Funding in the amount of $911,000 for these programs 

have been derived from Congestion Mitigation Air Quality (CMAQ) funds. On 

June 10, 1999, the Regional Transportation Commission of Clark County 

adopted Resolution No. 177 which established guidelines for administering the 

CAT MATCH commuter services program including the commuter incentive 

program, Club Ride. A copy of this resolution can be found in Appendix D, 

Section 2. Portions of the CAT MATCH program, which include employer based 

commuter incentives and area wide ridesharing programs, became operational in 

July, 1999. The voluntary TCM/TDM programs considered for implementation 

are estimated to achieve approximately 0.3 tons per day of emission reductions 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-5 
by the year 2000 at an estimated cost of $42,500 per ton of CO reduced. The 

reduction attributed to this measure is 0.08% of the amount necessary to attain 

the NAAQS. This value does not exceed the 3% maximum credit that is allowed 

to be claimed by EPA’s VMEP policy guidance. As participation increases in the 

Cat Match program it is estimated that the resulting emission benefit in 2010 and 

2020 will be 1.8 and 2.3 tons per day, respectively. A commitment to remedy 

any emission reduction shortfall is backed by separate resolutions from the Clark 

County Board of Commissions and the Regional Transportation Commission. A 

copy of the RTC resolution is contained in Appendix D, Section 9. 

Table 4-3 below addresses the eight acceptance criteria discussed for the 

voluntary TCM/TDM control measures that will be implemented. Additional 

supporting information related to this measure can be found in Appendix E,

Section 2. 

TABLE 4-3 

ACCEPTANCE CRITERIA FOR TCM/TDM AS A CO CONTROL MEASURE

ACCEPTANCE CRITERION HOW CRITERION IS MET 

Effectiveness An analysis conducted by Clark County

and the RTC indicate that the voluntary 

TCM/TDM program can reduce mobile 

source emissions by 0.08% or 0.3 tons 

per day. 

Safety The selected TCM/TDM elements of 

the Cat Match Program are considered 

safe with no other further implications

or risks. 

Cost Effectiveness The cost effectiveness of these 

measures are higher than other 

proposed measures but are lower than 

others previously considered and 

rejected. 

Availability of Technology This test is not applicable. 

Practicality The implementation of these measures

in other areas suggests that they are 

practical. 

Reasonableness These measures are considered 

reasonable when considered against 

other TCMs. 

Reliability Program elements may be difficult to 

administer across all segments of the 

population in a service based 

economy. 

Necessary for Attainment It is shown in Chapter 6 of this 

document that TCM/TDM programs are 

necessary for demonstrating 

attainment. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-6 
4.2.1.3 Technician Training and Certification 

The State’s Motor Vehicle Inspection/Maintenance (I/M) Program requires that 

inspectors be licensed. The training and certification procedures were 

established to comply with 40 CFR 51.367. The requirements for a certified 

inspector in Nevada’s I/M program are verified training, including a course 

approved by the Department of Motor Vehicles and Public Safety (DMV & PS), a 

written and practical testing program and a separate certification process. In 

general terms inspector training will cover: purpose and goals of enhanced I/M, 

emission control devices, configuration and inspection, test procedures and 

rationale. The I/M program also consists of training and licensing of class 2 

inspectors that conforms to the requirements set forth in 40 CFR 51.369. Under 

this requirement, a license is required to be a certified repair technician in order

to perform work or service on vehicle emission components. Additional 

information about these requirements are delineated in NAC 445B.485 through 

445B.5084 as well as the State of Nevada’s State Implementation Plan for an 

Enhanced Program for the Inspection and Maintenance of Motor Vehicles for Las 

Vegas Valley and Boulder City, Nevada (March 1996). 

The DMV & PS is the agency responsible for implementing and monitoring the 

State’s Motor Vehicle I/M Program including the Inspector Training and 

Certification programs. As specified in NRS 445B.765 and 445B.810, it is also 

the responsibility of DMV to prepare annual reports on the program and to submit 

them to the U.S. EPA in July of each year to comply with the provisions of 40 

CFR 51.366. Additional information on the Inspection Maintenance Program can 

be found in the Inspection Maintenance State Implementation Plan referenced 

above. 

The carbon monoxide emission reduction benefit from this control measure was 

derived from the Mobile5b model. This was accomplished by setting the I/M 

control flag record equal to 6 (IMFLAG = 6) and including a value of 2 in the third 

position of the corresponding input record. Setting these parameters in this 

fashion, the model applies the benefits of technician training and certification to 

the emission factors. A second model run was made keeping the inputs identical 

with the exception of not including the benefits of technician training. The 

resulting values from these two runs were then compared to determine the 

resulting benefit. The result of this analysis indicates that technician training and 

certification will provide a 2.95 % reduction in carbon monoxide emissions. 

Table 4-4 provides additional information on the acceptance criteria for 

technician training and certification as a control measure. 

 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-7 
TABLE 4-4 

ACCEPTANCE CRITERIA FOR TECHNICAIN TRAINING 

AND CERTIFICATION AS A CO CONTROL MEASURE

ACCEPTANCE CRITERION HOW CRITERION IS MET 

Effectiveness An analysis conducted by Clark County

utilizing the MOBILE model showed

this program can reduce mobile source 

emissions by 2.95% or 10.4 tons per 

day. 

Safety Training and certification is safe and 

can improve work place safety. 

Cost Effectiveness Training and certification are estimated 

to have a cost effectiveness of $115 

per ton of CO reduced and is the most 

cost effective measure. 

Availability of Technology This test is not applicable. 

Practicality The implementation of this measure in 

other areas suggests it is practical. 

Reasonableness Improving the effectiveness of 

emissions testing and repairs is a 

reasonable control measure. 

Reliability Training and Certification is 

administered by DMV & PS. This 

program has a high degree of reliability 

in reducing mobile source emissions. 

Necessary for Attainment It is shown in Chapter 6 that Technician 

Training and Certification is necessary

for demonstrating attainment. 

4.2.1.4 Alternative Fuels Program 

The Energy Policy Act of 1992 (EPACT) contains a number of titles that deal with 

the use and acquisition of alternative fuel vehicles. Realizing that this Act is

currently in the process of being amended, the final version should serve to 

further accelerate the acquisition and use of alternative fuel vehicles along with 

increasing fleet applicability. In the absence of applicable federal requirements, 

the State of Nevada has adopted an even more aggressive approach towards

acquisition / conversion of fleets. Nevada’s program is more aggressive by 

having an earlier implementation date and by including municipal fleets early in 

the implementation of the program. 

The Nevada Department of Conservation and Natural Resources, Division of 

Environmental Protection, is the agency responsible for administering the 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-8 
alternative fuels program. NRS 486A requires all governmental fleets in Clark

County to acquire and utilize clean alternative fuels vehicles. Starting in 1995,

10 percent of government fleets new vehicle purchases were required to be 

alternative fuels vehicles. This percentage increases to 90 percent in fiscal year

2001 and each year thereafter. Nearly all fleets have chosen to acquire natural 

gas vehicles and presently there are over 1,400 alternative fuel vehicles

operating in the Valley. As vehicles are replaced through attrition, this number 

will further increase along with the use of the cleaner fuel. Through the 

cooperative efforts of governmental agencies, eight natural gas fueling facilities

have been strategically located in the Las Vegas area. Additional information 

pertaining to this control measure can be found in Appendix E, Section 4.

It is estimated that the alternative fuel program in Clark County, Nevada will 

benefit CO emission reduction in the year 2000 by about 0.12%, or 0.4 tons per 

day at an estimated cost of about $4,000 per ton. This cost effectiveness based 

on the Phoenix Arizona Program. Clark County’s estimates are substantially

higher averaging $80,000 per ton of CO reduced. Table 4-5 enumerates the 

acceptance criteria for alternative fuels and presents arguments for the 

alternative fuel program as a primary control measure. 

In order to realize the maximum benefits of the alternative fuel control measure, 

entities will need to gain the support of private fleets through the Clean Cities 

initiative and possibly changes to the Energy Policy Act (EPACT) by providing 

more refueling facilities and unlimited public access to existing facilities. The 

most benefits of this control measure can be realized when dedicated vehicles 

are utilized because they are designed to operate efficiently on alternative fuels 

resulting in less CO pollution even though they may lack the advantages of 

longer range and the option of regular fuel that the dual-fuel fleet would afford. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-9 
TABLE 4-5 

ACCEPTANCE CRITERIA FOR THE ALTERNATIVE FUELS PROGRAM 

AS A CO CONTROL MEASURE

ACCEPTANCE CRITERION HOW CRITERION IS MET 

Effectiveness An analysis conducted by Clark County

indicates that the government fleets 

alternative fuels program can reduce 

mobile source emissions by 0.12% or 

0.4 tons per day. 

Safety Alternative fuel programs have been 

proven to be safe throughout the 

country. 

Cost Effectiveness* At $4,000 per ton of CO emission 

reduced, alternative fuels are 

considered as having an average cost 

effectiveness in comparison to other 

measures. 

Availability of Technology Alternative fuel technology has been in 

place for a while. Numerous vehicle 

manufacturers are providing a variety

of “clean” alternative fuel vehicles. 

Practicality The use of alternative fuel vehicles in 

other areas suggest that it is practical.

Additionally, most government fleets 

are currently attaining a 90% 

acquisition rate. 

Reasonableness This measure is considered 

reasonable.

Reliability Alternative fuels burn cleaner than 

gasoline in combustion engines this 

reliably reducing air pollution. 

Necessary for Attainment It is shown in Chapter 6 that the 

Alternative Fuel Program is necessary 

for demonstrating attainment. 

*Cost Effectiveness value based on Phoenix Arizona’s program. Clark County estimates of the cost effectiveness is 

substantially higher averaging $80,000 per ton of CO reduced. 

4.3 Off-Road Mobile Sources 

The only direct proactive controls affecting the off-road sources, mobile and 

otherwise, are the Wintertime Cleaner Burning Gasoline and the Oxygenated 

Fuels programs. Since this category contributes only about 11% of the total CO

emissions for the valley, further controlling these emissions would not be cost 

effective, nor practical. If in the future, control technology, cleaner fuels, or 

effective inspection programs became feasible, they will be incorporated into the 

SIP. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-10 
4.4 Stationary Point and Area Sources 

It is estimated that these source categories contribute only about 3% of the total 

CO emissions for the valley. As stationary sources are not a significant

contributor to CO levels, contributing only 1.39% of total emissions, the 

provisions of Section 187 (c) are not applicable to the Las Vegas Valley

Nonattainment Area. Other than current controls required by the new source 

performance standards (NSPS) and New Source Review (NSR) on major 

sources of pollution, no additional controls are warranted. 

4.5 Previously Adopted Control Measures 

Previously adopted control measures from the 1995 Moderate Area Carbon 

Monoxide Plan continue to assist in air quality improvement efforts. This section 

highlights those measures that were adopted and implemented and which 

continue to provide for CO emission reductions. 

Although fleet turn-over does not meet all required criteria of a federally

enforceable control measure, its effects in the Las Vegas Valley are significant. 

Nevada Department of Taxation records indicate that approximately 60,000 new 

vehicles are purchased annually. With total vehicle registrations increasing a 

modest 5 percent a year, the Las Vegas fleet has been experiencing a 14 

percent increase in new model year vehicles over the past three years. Since 

new cars emit pollution at a lower rate, the portion of newer vehicles comprising 

the Las Vegas fleet can lead to a significant reduction in mobile source carbon 

monoxide emissions.

Lower Reid Vapor Pressure (RVP) was adopted as a control in the 1995 

Moderate Area Carbon Monoxide Implementation Plan and continues to reduce 

CO emissions from fuel combustion in motor vehicles. The Nevada State 

Department of Business and Industry, Department of Agriculture was granted the 

authority to regulate the RVP by Chapter 590 of the Nevada Revised Statutes 

and Chapter 590 of the Nevada Administrative Code (NAC). Adopted by the 

Department of Agriculture, these regulations (NAC 590.065) lowered the RVP 

limit of gasoline from 11.0 psi to 9.0 psi with no waiver for ethanol blended fuel. 

The Department of Agriculture is the responsible agency for enforcing NAC 

590.065 which limits the vapor pressure of gasoline. Inspectors conduct 

approximately 88 random inspections per month. Analyses on gasoline samples

from gasoline stations are conducted by chemists in the Department’s laboratory. 

Results of each test are recorded in a database and monthly reports are 

prepared for the Division of Weights and Measures, the Bureau Chief, and 

Administrator of the Department of Agriculture. 

The 1995 Moderate Area Plan also contained 2.7% oxygenated fuels as a control 

measure. Since adopting these regulations, the Clark County District Board of

Health amended its regulations on September 27, 1997, to require that all fuel 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-11 
sold in Clark County during the winter season (October 1 to March 31) contain 

3.5% oxygenate by weight. Due to the higher oxygenate mandate, ethanol is

being used in lieu of MTBE to meet this requirement. The 3.5% oxygenate by 

weight control measure continues to provide cost-effective emissions reductions

within the non-attainment area. The AQD is responsible for monitoring and 

enforcing this control measure. 

The State’s Motor Vehicle Inspection Maintenance program, administered by the 

Department of Motor Vehicles and Public Safety, is also responsible for reducing 

carbon monoxide. Through the use of the MOBILE model, it has been estimated 

that this program is currently providing a 16.8 percent reduction of CO emissions. 

 

Table 4-5 below contains previously adopted and implemented controls 

(specified in the 1995 Carbon Monoxide AQIP) listed with their adoption date. 

TABLE 4-6 

PREVIOUSLY ADOPTED ENFORCEABLE 

CARBON MONOXIDE CONTROL MEASURES

Control Measure Adoption Date 

Oxygenate Fuels 1991/1995 

Reduced RVP Gasoline 1995 

Motor Vehicle Inspection/ 

Maintenance Program 

1978 

Fleet Turnover 1967 

4.6 Summary Of Primary Carbon Monoxide Control Measures 

The primary CO control measures discussed in the previous sections of this 

Chapter are summarized below in Table 4-7 with their emission benefit estimates 

for the attainment and future years along with the cost effectiveness. 

Contingency measures are discussed in Chapter 7 of this document. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-12 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 4-13 

TABLE 4-7 

PRIMARY CONTROL MEASURES, BENEFITS AND COST EFFECTIVENESS

2000 2010 2020 

Control Measure 

Cost 

Effectiveness 

($/ton) 

CO 

Benefit 

(TPD) 

CO 

Benefit 

(percent) 

CO 

Benefit 

(TPD) 

CO 

Benefit 

(percent) 

CO 

Benefit 

(TPD) 

CO 

Benefit 

(percent) 

Technician Training $ 115 10.42 2.95% 15.71 3.9% 23.89 4.1% 

CBG $ 1,225 31.92 9.8% 53.96 13.95% 96.55 17.3% 

Alternative Fuels $ 4,000 0.415 0.12% 1.12 0.28% 1.37 0.24% 

Cat Match TDM/TCM $ 42,500 0.295 0.08% 1.82 0.45% 2.33 0.40% 

 TOTALS 43.1 12.2% 72.6 18.1% 124.1 21.3% 
Chapter 5 - Air Quality Modeling

5.1 INTRODUCTION 

5.2 BASE CASE SCENARIO MODELING 

5.3 CARBON MONOXIDE EPISODE SELECTION AND DESIGN 

 VALUE 

5.4 ASSESSMENT OF UAM MODEL PERFORMANCE 
5.1 INTRODUCTION 

This chapter summarizes the modeling performed to establish an estimate of the 

amount of emission reduction needed to achieve attainment of the 8-hour 

average NAAQS for CO in the Las Vegas serious nonattainment area. Detailed 

technical documentation of the modeling can be found in Appendix C. 

Serious CO non-attainment areas, such as the Las Vegas Valley Air Basin, are 

required by the 1990 CAAA to utilize EPA approved models to demonstrate 

attainment. The Urban Air-shed Model (UAM), an urban-scale, threedimensional, grid-type, numerical simulation model which incorporates a 

condensed photochemical kinetics mechanism for urban atmospheres and the 

CAL3QHC, a micro-scale roadway intersection model are the current models of

choice for attainment demonstration. Since EPA has identified the UAM and 

CAL3QHC as effective tools for evaluating the effectiveness of emission control

programs needed to attain and maintain the CO national standard, these two 

models were selected for the attainment demonstration, in compliance with the 

CAAA requirements. 

The overall modeling system - comprised of transportation (TRANPLAN), 

emissions (MOBILE5b), and air quality models (UAM) - is initially used to 

replicate historic CO high pollution episodes in order to establish base case 

simulations. Each base case simulation relies on a wide variety of input data,

including meteorological data and inventories of estimated emissions from all 

significant sources of CO. Air quality modeling with the UAM is performed 

initially utilizing a set of inputs for a historic episode with elevated CO 

concentrations, and the results are evaluated to determine the performance of

the modeling system. Once the modeling system has been evaluated and 

determined to perform within prescribed levels, the same meteorological inputs 

and a projected emissions inventory are used to simulate the impact of future 

emission scenarios. 

Details regarding the protocol followed in the air quality modeling program for the 

Las Vegas Valley are provided in the report entitled “Modeling Protocol for the 

Las Vegas Valley Carbon Monoxide Urban Air-shed Model Update Project” dated 

September 11, 1996 (see Appendix C, Section 1). The modeling protocol report 

as well as technical support for the modeling program was provided by

ENVIRON International Corporation (ENVIRON). This chapter summarizes the 

results of air quality modeling for the 1996 base case scenario. A 

comprehensive report of the application of the UAM to the 1996 base case 

scenario is provided in a memorandum from ENVIRON describing the base case 

design value selection and scaling (October 27, 1998 - see Appendix C, Section 

4). EPA’s approval was obtained on the episode selection and scaling approach 

before the actual attainment demonstration modeling was performed. The 

employed scaling approach is defined and explained in details in the above 

referenced memorandum of October 27, 1998, Appendix C. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-1 
5.2 BASE CASE SCENARIO MODELING 

 

The key tasks accomplished in the air quality modeling program for the base 

case scenario were: 

(a) Selection of the CO episode to be modeled; 

(b) Preparation of meteorological, air quality and emission inventory data files;

and 

(c) Application of the UAM and assessment of model performance. 

The base case included the existing Inspection and Maintenance (I/M) program, 

the 3.5% oxygenated fuel program, low Reid Vapor Pressure gasoline (9 psi),

and other existing control measures that are in place or mandated by the Clean 

Air Act (CAA). 

5.3 CARBON MONOXIDE EPISODE SELECTION AND DESIGN VALUE 

In selecting an appropriate episode for UAM modeling of the Las Vegas Valley

area, the ten highest ambient air quality measurements of 8-hour CO

concentrations were selected based on peak 1- and 8-hour average CO 

concentrations above 8 PPM and 5.5 PPM, respectively in accordance with 

current modeling guidelines. Meteorological conditions were not the sole basis 

for selecting these periods, nor were the overall CO patterns throughout the Las

Vegas Valley. These top ten elevated CO episodes are listed in Table 5-1 below, 

along with the magnitude of peak hourly CO (evening and morning) and peak 8-

hour CO at East Charleston (EC) and Sunrise Acres (SA). Table 5-1 also lists

the time span of the peak 8-hour average at SA. 

Note that the highest 8-hour CO concentration occurs on December 8-9, 1996 

and on December 19-20, 1996 both of which coincide with the highest morning 

hourly CO of all episodes in the table. On December 8-9 and December 19-20 of 

1996, both evening and morning peaks are evident, with generally lower CO

levels across midnight ranging between 5-7 PPM. On December 4-5, however, 

only a short-lived evening peak occurs, and on January 9-10, 1997 

concentrations between the evening and morning peaks dip to 2 PPM. This 

indicates that sharp hourly peaks are not necessarily conducive to high 8-hour

CO, and that the maintenance of moderate to high CO levels overnight is more 

likely to lead to exceedences of the 8-hour standard. Considering these 

characteristics, the top two elevated CO episodes from the analysis are 

December 8-9 and 19-20, 1996. The third ranked episode is December 18-19 

based solely on peak 8-hour CO at both EC and SA over 7 PPM. 

The first two episodes (Dec 8-9 & Dec. 19-20) were isolated for further study and 

analysis as the result of extensive monitoring and meteorological data gathering 

efforts conducted as part of a detailed Carbon Monoxide study for the Las Vegas

Valley [The Las Vegas Valley Carbon Monoxide Urban Airshed Model Update 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-2 
Project - Phase II: UAM Base Case and Sensitivity Applications, Emery et al., 

July 1998 - (Appendix C, Section 3)]. 

As discussed in an October 27 memorandum to EPA (Appendix C), the selected 

episode was December 8-9, 1996. This selection along with the employment of 

a scaling factor that resulted in a maximum predicted concentration of 11.2 PPM 

were discussed with and approved by EPA Region IX. Figure 5-1 displays the 

UAM carbon monoxide concentrations for the selected episode of December 8-9, 

1996.

Table 5-1 

List of Highest 10 CO Episodes Based on Peak 1- and 8-hour Average CO 

Concentrations. Values Reported are for East Charleston (EC) and Sunrise 

Acres (SA). Peak 8-hour Period is Given for SA.

________________________________________________________________________

 Episode PM peak AM peak Peak Peak 

 hourly hourly 8-hour 8-hour 

 Period

 EC SA EC SA EC SA

________________________________________________________________

________ 

 1996 Dec 2-3 7.1 6.9 6.3 8.4 5.6 5.8 1900-0200 

Dec 3-4 8.7 9.0 7.6 9.4 6.2 6.9 1800-0100 

 Dec 4-5 10.5 9.5 3.5 2.5 6.7 6.7 1800-0100 

Dec 8-9 8.2 8.8 10.4 11.8 7.2 7.9 2000-0300 

Dec 18-19 8.8 8.5 8.2 9.1 7.2 7.4 1900-0200 

Dec 19-20 8.3 8.3 10.4 10.8 7.9 8.0 0100-0800 

Dec 25-26 6.5 7.1 8.1 9.2 5.8 6.2 0200-0900 

 1997 Jan 9-10 9.8 11.1 9.2 7.8 6.7 7.0 1800-0100 

Jan 18-19 7.5 8.2 5.9 5.9 5.8 6.6 2000-0300 

Jan 19-20 6.9 7.3 7.9 8.9 6.3 6.7 0100-0800 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-3 
Figure 5-1 

Analysis of Maximum 8-hour CO Concentration Measurements (PPM) 

In Central Las Vegas on December 8-9, 1996.

66

0

6

6

5 67

0

6

7

5 68

0

UT

M Easting (km)

3995400040054010

) (km ng rthi UTM No 7.2

4.

4

6.

3 3.9

4.

4

3.8 7.

9

5.

3

4.1

9.

9.6

1

9.5

4.6

6.3

3.

9

9.4 7.

8

4.1

5.9

1.1

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-4 
5.4 ASSESSMENT OF UAM MODEL PERFORMANCE 

Data inputs for the UAM were developed using available air quality,

meteorological, and emissions inventory data. Emissions inventory data for the 

selected carbon monoxide episode was derived from the “1996 Carbon 

Monoxide Emissions Inventory” discussed in Chapter 3 of this document. Both 

graphical and statistical measures of model performance were conducted. 

Statistical measures of model performance show numbers well within acceptable 

performance ranges established by the EPA in “Guidelines for Regulatory 

Application of the Urban Airshed Model for Areawide Carbon Monoxide, Volume I 

and II” dated March 1992. Table 5-2 below summarizes the resulting model 

performance statistics. 

Table 5-2 

Model Performance Statistics for December 8-9, 1996 

Comparing Scaled UAM 8-hour Average CO Concentrations 

with Measurements from all Sites Operated During the Field Study. 

Peak 8-hour Measurement 9.6 ppm at Marnell Field

Statistical

Measure

Revised Run (Phase IIb)

CO scaled by 1.14

Unpaired Peak (pp m) 11.2

Paired Peak (ppm) 9.6

UPPA (%) 17

PPA (%) 0

PPA Timing Error (hr) 0

Bias in Peaks (%) 3

Error in Peaks (%) 14

Timing Bias (hr) -1

Timing Error (hr) 3

Overall Bias (%) 1

Overall Error (%) 17

Graphical representation is illustrated in a sample time series plot in Figure 5-2. 

For the complete set of time series plots, the reader is referred to Appendix C, 

Section 3. These time series plots show that model results agree well in timing at 

all monitored site locations. Based on model performance statistics, the time 

series plots, and meteorological conditions, EPA Region IX concurred that the 

December 8-9 modeling episode was representative of high CO concentrations 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-5 
in the Las Vegas Valley and therefore should be used for attainment 

demonstration purposes. 

Figure 5-2 

Graphs Comparing Observed CO Concentrations (large dots) and UAM Predicted Concentrations 

(solid line) at a Corresponding Site. The Dashed Lines Represent the Minimum and Maximum 

Predicted CO Concentrations with the Surrounding Nine-cells Around Each Site.

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 5-6 
Chapter Six – Demostration of Attainment

6.1 INTRODUCTION 

6.2 2000 BASE YEAR (NO ACTION SCENARIO) 

PROJECTIONS 

6.3 UAM ATTAINMENT DEMONSTRATION 

6.4 CAL3QHC ROADWAY INTERSECTION MODELING 

6.5 MICRO-SCALE ANALYSIS FOR AIRPORTS
6.1 INTRODUCTION 

Air quality modeling is an integral part of the air quality planning process to 

achieve attainment of the NAAQS. This chapter summarizes the application of

the UAM and CAL3QHC models in the demonstration of attainment of the CO 

NAAQS by December 31, 2000. The primary purpose for conducting UAM areawide and CAL3QHC roadway intersection modeling is to demonstrate the 

effectiveness of control strategies in attaining the 8-hour average NAAQS for CO

(EPA/SYSAPP-92/045a, pg 49). The attainment demonstration should consist of 

the following four parts: 

1. Development of the attainment-year base case emission 

 inventory; this inventory reflects the net effect of existing required 

 controls and growth projections for all source categories; 

2. Development of future-year emission strategies; 

3. Performing attainment year model simulations to assess control 

 strategies; and 

4. Using results from both the UAM and CAL3QHC modeling to 

demonstrate attainment. 

With respect to utilizing the UAM area-wide model to demonstrate attainment, the

estimated 8-hour average concentrations must be below the 9.0-ppm standard. 

EPA also recommends that the CAL3QHC model be applied to intersections at

potential hot-spot locations. The hot-spot modeling analysis entails combining 

concentrations from the UAM with those derived from the CAL3QHC micro-scale 

model. 

This chapter concludes with a discussion about a micro-scale analysis, which 

was conducted on the airport facilities in the Las Vegas Valley. The purpose of

this analysis is two fold: 1) to incorporate updated emission estimates from the 

Clark County airports into the plan and the attainment demonstration, and 2) to 

establish future years emission budgets for airport sources as a means to 

facilitate future conformity determinations. 

6.2 2000 BASE YEAR (NO ACTION SCENARIO) PROJECTIONS 

To initiate attainment demonstration modeling, a future year CO emission 

inventory representative of the year 2000, without any control measures, was 

prepared for future year application of the UAM. This projected inventory is the 

basis for evaluating the potential CO reductions from a variety of proposed 

control measures. The development of the base case (no action scenario) future 

year projected inventory followed EPA guidance contained in the document titled

“Procedures for Preparing Emission Projections” (EPA-450/4-91-019). Per EPA 

guidance, these emissions reflect current regulations, or any regulations that will 

be in effect prior to the year 2000, and the anticipated effects of any controls 

mandated by the 1990 CAAA. Two approaches were used to develop the Las 

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-1 
Vegas 1996 and 2000 base year inventories. The 1990 base inventory was used 

as the basis for projecting the 1996 and 2000 background inventories utilizing 

Bureau of Economic Analysis growth factors and local data for stationary, area, 

and non-road sources. The on-road mobile source inventory was derived 

utilizing MOBILE5b containing inputs representative of 1996 and 2000

conditions. Additional information pertaining to the projected future year

emission inventory can be found in the modeling documentation contained in 

Appendix C, Section 4 and Appendix E, Section 5. 

The mobile source emissions were combined with the emissions from other 

sources and run through the Urban Airshed Model for a selected episode. Table 

6-1 depicts the 1996 base year emission inventory, the 2000 base year 

(uncontrolled, no action scenario) emission inventories used in the modeling

analysis along with the 2000 controlled emission inventory. 

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-2 
Table 6-1 

1996 & 2000 BASE YEARS CARBON MONOXIDE MODELING 

EMISSIONS FOR THE LAS VEGAS NON-ATTAINMENT AREA

 1996 Base 2000 Uncontrolled 2000 Controlled

 Emissions Emissions Emissions 

 SOURCE CATEGORIES (Tons/Day) (Tons/Day) (Tons/Day)

Bonanza Materials 0.28 0.28 0.28

James Hardie Gypsum 0.55 0.55 0.55

Southern NevadaPaving 0.55 0.55 0.55

Pabco Cogeneration 0.55 0.55 0.55

Georgia Pacific 0.62 0.62 0.62

Total Point Sources 6.53 6.53 6.53

AREA SOURCES

Small Stationary 2.7 3.08 3.08

Boiler Emissions 0.38 0.43 0.43

Fireplaces 2.12 2.59 2.59

Structural Fires 0.64 0.78 0.78

Vehicular Fires 0.05 0.06 0.06

Brush Fires 1.26 1.54 1.54

Residential NG Combustion 0.31 0.34 0.34

Commercial NG Combustion 0.09 0.10 0.10

Industrial NGCombustion 0.32 0.36 0.36

Electrical Utility NG 0.56 0.63 0.63

Cigarette Smoking 0.04 0.05 0.05

Total AreaSources 8.47 9.96 9.96

NON-ROAD MOBILE SOURCES

County Airports 36.4 40.4 40.4

Nellis AFB 2.86 2.86 2.86

Locomotive Emissions 0.23 0.23 0.23

Lawn and Garden Equipment 3.57 3.52 3.52

MC& Recreation Equipment 5.9 5.86 5.86

Construction Equipment 9.77 7.61 7.61

Total Non-Road Sources 58.73 60.48 60.48

ON-ROAD MOBILE SOURCES* 405.4 353.23 310.18

GRAND TOTAL 479.13 430.20 387.15

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-3 
6.3 UAM ATTAINMENT DEMONSTRATION 

The 1996 and 2000 base conditions reflect changes to the roadway network that 

either were completed, or will be be completed under the latest RTC Fiscal Year

1998-2000 Transportation Improvement Program (TIP). Thus, changes in VMT,

speed and vehicle occupancy rates are included in the base scenarios. 

Likewise, CO emission reductions associated with existing control measures

(oxygenated fuel program, low RVP, and the smog check program) and 

regulatory measures for stationary, area, and non-road mobile source categories,

as discussed in Chapter 4, are also incorporated in the base condition modeling. 

To demonstrate attainment of the CO NAAQS, the results from the UAM

modeling analyses must indicate that maximum concentrations greater than 9.0 

PPM will not occur. Demonstration of attainment by December 31, 2000 was

accomplished by modeling the mobile source control measures introduced in 

Chapter 4 and depicted in Table 6-2 below. Mobile source emission factors and 

traffic volumes were then input into the DTIM2 (Direct Travel Impact Model) and 

then input into the EPS2 model to calculate total area-wide uncontrolled 

emissions. Next, the UAM was run to determine the effects of the control 

measures. Consequently, the UAM results indicated that the proposed control 

measures provide sufficient reductions and that the maximum concentration on 

the attainment date would be 8.1 PPM. 

Additionally, to validate the UAM attainment demonstration, the micro-scale hotspot analysis combines the results from the roadway intersection modeling and 

the area-wide modeling and should show no predicted 8-hour maximum 

concentrations greater than 9.0 PPM. Of the three-modeled intersections, the 

East Charleston/Eastern intersection has the highest predicted CO 

concentrations (see Section 6.4 below). It is shown later that this plan results in 

sufficient emission reductions such that the intersection falls below the 8-hour 

CO NAAQS of 9.0 PPM at 8.3 PPM. This value is below the attainment 

threshold of 9.0 PPM, therefore, attainment is demonstrated. A more complete 

description of the UAM CO modeling performed for the Las Vegas Valley is 

provided in following documents: The Las Vegas Valley Carbon Monoxide Urban 

Airshed Model Update Project - Phase II: Modeling to Demonstrate Attainment of 

the Carbon Monoxide Standard (contained in Appendix C, Section 4) and the 

Supplemental Urban Airshed Modeling Analysis for the Las Vegas Valley Carbon 

Monoxide Attainment Demonstration (contained in Appendix E, Section 5). 

It is important to mention that the attainment demonstration is considered as 

being conservative as it does not include the benefits of On-Board Diagnostics

(OBD) programs and Tier II motor vehicle technology. At present, the benefit of 

reduce CO emissions are unquantifiable, but are expected to yield significant 

reductions in future years. 

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-4 
TABLE 6-2 

PROPOSED ENFORCEABLE CO CONTROL MEASURES 

Control Measure 

Year 2000 

Emission 

Reduction 

Adoption Date Responsible Agency 

Clean Burning Gasoline 9.8% 1999 Health District 

Voluntary Transportation Control 

Measures / Transportation 

Demand Management 

0.08% 1999/Ongoing RTC 

Technician Training and 

Certification 2.95% 1988 DMV&PS 

Alternative Fuels Program for 

Government Fleets 0.12% 1991/Ongoing NDEP/Govt. Entities

Combined Effect of Controls 12.2% 

Combined effects of controls are not cumulative 

Table 6-3 below depicts the maximum ambient concentrations resulting from the 

UAM modeling runs. 

Table 6-3 

MAXIMUM VALLEY WIDE PREDICTED UAM CONCENTRATIONS

Run Controls 1996 2000 2010 2020

(ppm) (ppm) (ppm) (ppm)

Base Case 

11.2 9.1 8.7 10.5 

Control 

Case 

CBG, Technician 

Training, Alternative 

Fuels, TCM/TDM N/A 8.1 7.2 8.5 

6.4 CAL3QHC ROADWAY INTERSECTION MODELING 

As previously indicated the EPA recommends that a micro-scale “hot-spot” 

analysis also be conducted as part of the attainment demonstration. Typically, 

three intersections having high traffic volumes, poor levels of service, and being 

in close proximity to the monitoring station recording exceedences are the basic

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-5 
selection criteria for this analysis (EPA 454/R92-005, pg. 3). As such, the 

intersections referred to as the “5 points” were selected to be modeled to meet

the micro-scale and attainment demonstration modeling requirements. 

The three intersections which comprise the “5 points” include: East Charleston 

and Eastern, East Charleston and Fremont, and Eastern and Fremont and are 

located approximately one half mile southwest of the Sunrise Acres monitoring 

station. A location map depicting the configuration of “5 points” is provided below 

in Figure 6-1. 

Figure 6-1 

CAL3QHC INTERSECTION LOCATION MAP

The modeling approach involved estimating 8-hour “running” average CO

concentrations at the three intersections for the 2000-attainment year. The 8-

hour running average was calculated by the following method: 

 (1) Modeling hourly concentrations over a 24-hour period using the 

CAL3QHC microscale model; 

(2) Combining micro-scale concentrations with background or 

neighborhood CO concentration generated from the UAM; and 

(3) Calculating a “running” average of concentrations over the highest 

continual eight hours. 

In the CAL3QHC modeling, an array of receptors is placed around each selected 

intersection in accordance with EPA guidance. In the UAM modeling, an

average concentration is estimated for each one square mile grid cell. The UAM 

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-6 
“background” component for a given intersection is obtained by computing a 

weighted average of the concentrations from the four nearest UAM grid cells. To 

combine the UAM and CAL3QHC modeling results, hourly concentration 

estimates from each model are summed, and then 8-hour running averages are 

computed. Predicted CAL3QHC and UAM combined maximum 8-hour CO 

concentrations for the three roadway intersections are provided in Table 6-4 

below. For detailed information on the CAL3QHC analysis, the reader is referred 

to the document titled “Micro-scale Hot Spot Modeling with CAL3QHC for the Las

Vegas Carbon Monoxide SIP, contained in Appendix E, Section 6. 

The predicted and combined maximum CO concentrations at the three roadway 

intersections all were within the 8-hour national standard of 9.0 PPM. The 

predicted values support the contention that the existing and proposed control 

measures will result in the Las Vegas Valley reaching attainment of the CO 

NAAQS by the prescribed date of December 31, 2000. For additional details, the 

reader is referred to Appendix E, Sections 5 and 6, Supplemental UAM Modeling 

Documentation. 

Table 6-4 

MAXIMUM PREDICTED 8-HOUR CARBON MONOXIDE CONCENTRATIONS 

FOR HOT SPOT INTERSECTIONS

2000 2010 2020

Intersections 

Maximum Maximum 

UAM UAM+CAL3Q 

(ppm) (ppm) 

Maximum Maximum 

UAM UAM+CAL3Q 

(ppm) (ppm)

Maximum Maximum 

UAM UAM+CAL3Q 

(ppm) (ppm)

Charleston/Eastern 5.9 8.3 5.2 7.3 5.7 7.6 

Charleston/Fremont 5.9 6.7 5.2 5.9 

 

 5.7 6.4 

Eastern/Fremont 5.9 7.6 

 

 5.2 6.6 5.7 7.4 

6.5 MICRO-SCALE ANALYSIS FOR AIRPORTS

Towards the conclusion of the modeling analysis in 1999, updated emission 

estimates from civilian airports and related support activities became available.

These new emission estimates were higher than values previously quantified and 

reported. It was also postulated that contributions from airport sources could be 

better represented, both in magnitude and timing/location with models other than 

the UAM, leading to a more accurate representation of air quality in the vicinity of 

airports. To reduce all uncertainties related to higher, updated emission 

estimates and potential modeling limitations of the UAM, a separate modeling 

analysis was conducted utilizing the Emissions and Dispersion Modeling System 

(EDMS).

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-7 
The EDMS was developed specifically for airport emission analyses and is

approved by the EPA. EDMS is a combined emissions and dispersion model for

assessing air quality at civilian and military airfields. The model was developed

by the Federal Aviation Administration (FAA) in cooperation with the United 

States Air Force (USAF). The primary aspects of the model include the 

development of an inventory of emissions generated by sources within and 

around an airport, and the calculation of pollutant concentrations in the 

surrounding environment. 

EDMS performs dispersion analyses by incorporating previously developed 

dispersion models (PAL2 and CALINE3-both EPA validated for the various

sources of emissions). These earlier models have many known assumptions

and limitations regarding their application. Assumptions used in the dispersion 

analysis module include: a simple or relatively flat terrain, conservation of mass

(i.e., negligible chemical breakdown of original substance), and steady state 

atmospheric conditions over the averaging period of one hour. Additionally,

Gaussian dispersion algorithms used by EDMS are limited to transport distances

of less than 50 kilometers and do not consider complex aerodynamic effects 

such as downwash from buildings. Pollutants currently included in EDMS for 

dispersion analyses are carbon monoxide (CO), oxides of nitrogen (NOx), oxides

of sulfur (SOx), and particulate matter less than 10 microns in diameter (PM-10). 

As illustrated in a protocol submitted to the EPA, Region IX (see Appendix C), 

this section summarizes the results from modeling CO at three Clark County 

airports within the Las Vegas Valley using EDMS. The resulting concentrations 

from EDMS are added to UAM predicted “background” concentrations to provide 

a total CO concentration field for each scenario modeled, much the same way

micro-scale intersection modeling is performed as described by EPA’s CO

modeling guidance (EPA, 1992). 

The total 8-hour average CO concentrations at the individual receptors are then 

rank-ordered to show the highest resulting concentrations, at which point an 

attainment/maintenance evaluation can be made. A more complete and detailed 

description of the methodology used to model the atmospheric dispersion of 

airport-related CO emissions is provided in the report “Carbon Monoxide

Emissions Inventories and Dispersion Modeling, McCarran International, North 

Las Vegas, and Henderson Executive Airports” prepared by Ricondo & 

Associates , 1999 (see Appendix C, Section 8). 

Table 6-5 below depicts the EDMS/UAM results. All predicted future year 8-hour 

CO levels are below the standard, except for one McCarran receptor in 2020 

(9.07 ppm). The EDMS concentration at that point is only 0.17 ppm and the 

UAM component is 8.90 ppm. The future year UAM control strategy reported by 

Emery at al. (1999) indicate that adoption of one primary control measure (such 

as Cleaner Burning Gasoline) would reduce overall peak UAM concentrations 

from 10.8 ppm to 9.1 ppm, about a 16% reduction. Applying this same 16% 

_____________________________________________________________________________

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-8 
_____________________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 6-9 

reduction to the UAM background concentration at the EDMS receptor would 

reduce the 8.90 ppm value to 7.50 ppm (8.90 ppm X .84 = 7.50 ppm). Even 

assuming that this control measure has no effect on McCarran sources, the 9.07 

ppm peak in Table 6-5 reduces to 7.67 as a result of the CBG control measure 

(7.50 ppm + 0.17 ppm = 7.67 ppm). Therefore, this analysis shows attainment in 

2000 and maintenance in 2010 and 2020 with the adoption of the primary CO 

control measures. 

Table 6-5 

MAXIMUM 8-HOUR CARBON MONOXIDE CONCENTRATIONS (PPM) 

FROM COUNTY OPERATED AIRPORTS FOR FOUR MODELING YEARS 

(BASE CASE ESTIMATES ASSUME NO ADDITIONAL CONTROLS ON MOTOR VEHICLES)

 EDMS CO UAM CO Total CO 

Airport Scenario Receptor Airports Uncontrolled Uncontrolled

McCarren Airport 1996 Base 277 0.00 9.64 9.64 

2000 Base 277 0.01 8.66 8.67 

2010 Base 277 0.01 8.06 8.07 

2020 Base 1599 0.17 8.90 9.07 

North Las Vegas Airport 1996 Base 801 0.00 8.89 8.89 

2000 Base 801 0.00 7.54 7.54 

2010 Base 801 0.00 7.03 7.03 

2020 Base 801 0.01 8.27 8.28 

Henderson Airport 1996 Base 92 0.14 0.43 0.57 

2000 Base 92 0.19 0.39 0.58 

2010 Base 204 0.04 0.51 0.55 

2020 Base 181 0.09 1.08 1.17 

The results of this airport micro-scale analysis serve to ensure that projected 

increased emissions from this source category can be accommodated within the 

Valley’s Carbon Monoxide airshed without jeopardizing attainment or 

maintenance of the CO NAAQS.
Chapter Seven - Additional Requirements of the 

1990 CAAA

7.1 INTRODUCTION 

7.2 VMT TRACKING PROGRAMS 

 

 7.2.1 VMT Projections 

 7.2.2 Contingency Measures 

 7.2.3 Annual VMT Tracking 

7.3 OTHER CONTROL MEASURES
7.1 INTRODUCTION 

This section addresses requirements applicable to non-attainment areas set forth 

by the 1990 CAAA. The VMT Tracking Program is first discussed and includes 

VMT projections and contingency measures that will be implemented should 

either actual VMT exceed projected VMT or if attainment of the federal CO

standard is not reached. Also contained in this section is a brief discussion of 

annual VMT tracking and reporting. 

Both sections 172(c)(9) and 187(a)(3) of the 1990 CAAA require contingency 

measures to be implemented in the event the area fails to reach attainment by

the specified attainment date. Such measures shall be included in the SIP 

revision to take effect automatically without further action by the State or EPA.

The trigger for such measures is an official finding by EPA that the area failed to 

attain the CO standard by the applicable attainment date. Section 187(a)(3) also 

requires the Las Vegas Valley to implement contingency measures if any

estimate of actual VMT or any updated VMT forecast for the area contained in an 

annual report for any year prior to attainment exceeds the number predicted in 

the most recent VMT forecast, within a specified margin of error. 

7.2 VMT TRACKING PROGRAMS 

7.2.1 VMT Projections 

Section 187(a)(2)(A) of the 1990 CAAA requires CO non-attainment areas to 

forecast VMT for each year prior to the attainment year. The first set of 

projections contained in this plan serves to satisfy this requirement. In addition,

the accuracy of the VMT forecasts will be tracked through annual reports that 

present estimates of actual VMT for the preceding year and updates of the VMT

forecasts for subsequent years. A deviation from the forecasted VMT of a given 

percentage will cause implementation of contingency measures to offset either

excess VMT or CO emissions due to the additional VMT. These percentages are 

5 percent in 1999, 4 percent in 2000, and 3 percent in 2001 and subsequent

years. The cumulative VMT growth cannot be greater than or equal to 5 percent

above the VMT forecast used as the basis for attainment demonstration. Annual 

VMT tracking reports containing the estimated and actual reported VMT for each 

year is due in September of each year and will be submitted by the RTC. 

The RTC is responsible for preparing VMT forecasts. The Nevada Department

of Transportation has the responsibility of estimating actual VMT in conjunction 

with the Highway Performance Monitoring System and reporting these values to 

the Federal Highway Administration. The DCP will work with the RTC to prepare 

the annual VMT tracking reports. The VMT projections for future years were 

derived using the Las Vegas Regional Transportation Model developed and 

maintained by the RTC. Table 7-1 contains VMT forecasts for each year prior to 

the 2000 attainment year as well as for the horizon years beyond 2000. Note 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 7-1 
that average daily VMT will decline after the year 2020 due to the assumption 

that highways will saturate with traffic and will exceed their capacities resulting in 

commuters selecting alternate modes of travel like mass transit, ride sharing, and 

other modes. 

TABLE 7-1 

AVERAGE DAILY VMT ESTIMATES AND FORECASTS BY FUNCTIONAL CATEGORY AND BY YEAR*

Segment 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Ext. Connector 640,605 682,315 724,024 765,734 800,857 835,981 871,105 906,229 941,353 976,477 1,011,600

Fwy Ramps 69,247 79,803 90,359 100,916 104,915 108,914 112,913 116,912 120,912 124,911 128,910

Minor Arterial 7,469,945 7,627,173 7,784,400 7,941,628 8,313,494 8,685,360 9,057,227 9,429,093 9,800,959 10,172,825 10,544,691

Major Arterial 3,655,885 3,706,998 3,758,111 3,809,224 3,923,028 4,036,831 4,150,635 4,264,438 4,378,242 4,492,045 4,605,849

Ramps 267,724 277,203 286,683 296,162 311,904 327,646 343,388 359,130 374,872 390,614 406,356

Interstate 3,825,711 3,910,446 3,995,180 4,079,915 4,249,168 4,418,422 4,587,675 4,756,929 4,926,182 5,095,435 5,264,689

Freeway 1,202,253 1,361,497 1,520,741 1,679,985 1,849,208 2,018,432 2,187,655 2,356,878 2,526,102 2,695,325 2,864,548

Expressway 214,097 240,631 267,164 293,698 299,422 305,147 310,871 316,595 322,319 328,043 333,767

Collector 2,776,775 2,981,164 3,185,553 3,389,942 3,693,134 3,996,327 4,299,519 4,602,711 4,905,904 5,209,096 5,512,288

Local 2,185,695 2,255,455 2,325,216 2,394,976 2,498,849 2,602,721 2,706,594 2,810,466 2,914,339 3,018,211 3,122,084

Intrazonal Trips 100,028 103,487 106,947 110,406 114,910 119,414 123,918 128,422 132,927 137,431 141,935

Public Transit 61,054 63,003 64,951 66,900 79,880 92,860 105,840 118,820 131,800 144,780 157,760

VMT Totals 22,469,020 23,289,175 24,109,330 24,929,485 26,238,770 27,548,054 28,857,339 30,166,623 31,475,908 32,785,192 34,094,477

Segment 2010 2011 2013 2015 2020 2021 2022 2023 2024 2025 2030

Ext. Connector 1,116,972 1,152,480 1,223,495 1,294,511 1,472,049 1,477,261 1,482,472 1,487,684 1,492,896 1,498,107 1,524,166

Fwy Ramps 140,908 145,306 154,104 162,901 184,895 183,557 182,219 180,880 179,542 178,203 171,511

Minor Arterial 11,660,290 12,112,245 13,016,155 13,920,065 16,179,840 16,122,155 16,064,470 16,006,784 15,949,099 15,891,414 15,602,988

Major Arterial 4,947,259 5,148,238 5,550,196 5,952,154 6,957,048 6,911,219 6,865,390 6,819,561 6,773,731 6,727,902 6,498,757

Ramps 453,583 473,322 512,800 552,278 650,973 646,539 642,104 637,670 633,235 628,801 606,628

Interstate 5,772,449 5,952,793 6,313,481 6,674,170 7,575,890 7,543,749 7,511,608 7,479,467 7,447,326 7,415,185 7,254,480

Freeway 3,372,218 3,613,678 4,096,597 4,579,517 5,786,816 5,731,012 5,675,208 5,619,404 5,563,601 5,507,797 5,228,778

Expressway 350,939 359,350 376,172 392,995 435,050 435,495 435,939 436,384 436,829 437,274 439,498

Collector 6,421,865 7,018,499 8,211,766 9,405,033 12,388,200 12,417,274 12,446,347 12,475,421 12,504,495 12,533,569 12,678,937

Local 3,433,701 3,627,784 4,015,949 4,404,114 5,374,527 5,359,132 5,343,737 5,328,342 5,312,947 5,297,552 5,220,577

Intrazonal Trips 155,447 168,867 195,706 222,546 289,645 288,815 287,986 287,156 286,326 285,497 281,348

Public Transit 196,700 196,770 196,910 197,050 197,400 197,470 197,540 197,610 197,680 197,750 198,100

VMT Totals 38,022,330 39,969,331 43,863,331 47,757,332 57,492,333 57,313,677 57,135,020 56,956,363 56,777,707 56,599,050 55,705,767

* Estimates for 1997, 2000, 2010,2020, and 2030 are based on RTC's TRANPLAN runs

Other values have been interpolated. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 7-2 
7.2.2 Contingency Measures 

Section 187(a)(3) of the 1990 CAAA requires that contingency measures be 

included in the attainment plan. These measures are required to be 

implemented if a non-attainment area fails to attain the federal standard by the 

designated attainment date. Additionally, a deviation from the projected VMT of 

more than 3% will also trigger implementation of contingency measures to offset 

excess VMT and associated mobile source CO emissions (U.S. EPA, 1992). 

If sufficient emission reductions needed to attain the federal CO air quality 

standard are not achieved as anticipated, or if actual VMT exceed projected VMT 

by 3%, the contingency measures listed in Table 7-2 below will be implemented 

according to the severity of ambient exceedance or VMT increase. EPA 

guidance does not mandate a specific reduction level that contingency measures 

must achieve. However, EPA considers measures that offset one year VMT 

growth to be an appropriate guideline. For the Clark County nonattainment area, 

annualized VMT growth from 2000 to 2005 is 5 percent. At a minimum, 

contingency measures should provide CO emission reductions to counteract the 

effect of one year’s growth in VMT, or at least to offset the emissions caused by 

the incremental increase in VMT forecasted in Table 7-1 above. 

TABLE 7-2 

CONTINGENCY MEASURES

MEASURE AGENCY RESPONSIBLE 

FOR IMPLEMENTATION 

IMPLEMENTATION 

TRIGGER 

On Board Diagnostics 

II (OBDII) Testing 

Department of Motor 

Vehicles & Public Safety

9.5 ppm – 11 ppm exceedance 

3% - 5% VMT increase 

Lower I/M Program 

 Cutpoints 

Department of Motor 

Vehicles & Public Safety

11 ppm – 15 ppm exceedance 

5% - 10% VMT increase 

On Road Remote 

 Sensing 

Department of Motor 

Vehicles & Public Safety

11 ppm – 15 ppm exceedance 

5% - 10% VMT increase 

The contingency measures selected do have the potential to significantly reduce 

CO emissions. Due to the limitations of existing models to quantify the emission 

reductions from these programs, accurately quantifying the actual reduction is 

problematic. With respect to On Board Diagnostics II (OBDII) testing, the EPA’s 

MOBILE6 model would be the appropriate tool to use in determining the 

effectiveness of this measure. Unfortunately, this model is still in the process of 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 7-3 
development. Based on EPA’s draft document titled, Determination of CO Basic 

Emission Rates, OBD and I/M Effects for Tier I and Later LDVs and LDTs 

(EPA420-P-99-017), OBDII testing has significant potential to reduce CO 

emissions. Until the official release of MOBILE6, it is not possible to quantify the 

benefits from this contingency measure. EPA has indicated that Clark County 

could use the Cold CO model to quantify this benefit. However, this model uses 

assumptions that are not consistent with the MOBILE5 model used in the SIP. 

Lowering the cutpoints associated with the State’s Vehicle Inspection/ 

Maintenance Program will also result in reduced emissions as vehicles will have 

to meet more stringent testing standards. The MOBILE model is the appropriate 

tool to utilize for estimating the benefits attributed to lowering the cutpoints. The 

limitations prohibiting the use of this model at this time is the fact that only one 

data set of cutpoints, for a two-speed I/M test, is available. Based on 

conversations with EPA’s OTAQ Division, it may be possible for additional data 

sets to be developed. Once new data sets are developed, it will then be possible 

to run the MOBILE model to estimate the effects of lower I/M program cutpoints. 

Clark County is committed to working with EPA, Region IX and OTAQ on this 

issue and will incorporate this analysis in a future SIP revision. 

On-road Remote Sensing of high emitting vehicles is another contingency 

measure that has the potential to reduce CO emissions. EPA has developed 

draft guidance (EPA420-P-98-007) and a utility program that works in conjunction 

with the MOBILE model to estimate the effects of remote sensing. Although the 

focus of this guidance is predominately on clean screening, it also looks at the 

application of remote sensing to identify high emitting vehicles. Clark County 

attempted to seek authorization from OTAQ on the use of this draft guidance and 

utility program to estimate the emission reduction benefit. Because of the draft 

status of the guidance and the inability to obtain authorization to use the draft 

utility program, it is not possible to provide a defensible emission reduction for 

this contingency measure. It is important to mention that Clark County’s analysis 

using the RSD utility program indicates that a 1.3% reduction in mobile source 

emissions.

As indicated above, it is not possible to quantify the emission reductions and 

effectiveness of the contingency measures at this time. From a qualitative 

perspective however, these contingency measures will be effective at reducing

emissions upon their implementation and should provide ample reduction to 

offset emissions associated with a 5 percent growth in VMT. Related to all the 

contingency measures specified above, Clark County will prepare and submit a 

SIP revision that quantifies the actual benefits of these contingency measures, 

within one year of the release date of MOBILE6 (or its successor), guidance and 

applicable models. This commitment will be contained in the Clark County Board 

of Commissioners resolution adopting this plan. Should the contingency measure 

analysis indicate that the proposed contingency measures do not provide ample 

reductions, the SIP revision will include additional contingency measures. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 7-4 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 7-5 

EPA expects that actions needed for full implementation of contingency 

measures occur within 60 days after EPA notifies the area of its failure to attain. 

EPA has also concluded that, to be beneficial, contingency measures must be 

fully implemented within 12 months after EPA’s findings (Technical Support 

Document to Aid States with the Development of Carbon Monoxide SIPs, EPA - 

July 1992). Legislation and regulations currently exist in NRS 445B and NAC 

445B, respectively, that allow for changes to the cutpoints in the I/M program and 

to allow for on-road remote sensing to be conducted. The Nevada Department of 

Environmental Protection is proceeding with regulation changes that will require 

OBDII testing be incorporated into the existing I/M program. It is anticipated that 

the State Environmental Commission will adopt these regulation changes by 

July, 2000. With the adoption of these regulations, these contingency measures 

will be able to be implemented in a timely manner, without further action. 

Appendix E, Section 8, also contains a discussion on other potential contingency 

measures and the reasons why each was not selected. 

7.2.3 Annual VMT Tracking 

Annual reports updating VMT forecasts and presenting VMT estimates for the 

previous year are required under Section 187(a)(2). As previously stated, the 

DCP will work with the RTC to prepare annual VMT tracking reports. These 

annual reports will contain estimates of actual VMT in the previous year, 

forecasts of VMT in future years, and verification that supplemental (contingency) 

control measures are being implemented if actual VMT estimates for previous 

years exceed earlier forecasts. Annual VMT tracking reports will be submitted to 

the EPA in September of each year beginning in the year 2000 and following 

EPA reporting guidelines. A resolution adopted on July 13, 1995 by the Regional 

Transportation Commission committing to preparing and submitting an annual 

VMT tracking report is contained in Appendix D, Section 8. 

7.3 OTHER CONTROL MEASURES 

Future monitoring data will indicate the amount of progress being made towards 

attainment. Should this data reveal that additional steps are necessary to reach 

attainment by December 31, 2000, steps will be taken to further program 

activities of the insurance measures contained in Table 7-3 below.

TABLE 7-3 

OTHER CONTROL MEASURES

MEASURE RESPONSIBLE AGENCY 

Voluntary Vehicle Repair Program Clark County, DMV & PS 

Smoking Vehicle Telephone Hotline DMV & PS 
Chapter Eight –Implementation/SIP Commitments

8.1 IMPLEMENTATION 

8.2 SIP IMPLEMENTATION, MONITORING AND REPORTING 

 

8.3 MAINTENANCE 

 

8.4 MOBILE SOURCES EMISSIONS BUDGET 

 

8.5 ADDITIONAL COMMITMENTS TO INSURE CONFORMITY 
8.1 IMPLEMENTATION 

Implementation of the control measures specified in Chapter 6 is necessary for 

the Valley to attain the CO NAAQS. The responsibility for implementing these 

control measures lies with the following governmental entities: the Clark County

Health District, Air Pollution Control Division; the Nevada Department of 

Conservation and Natural Resources, Division of Environmental Protection; and 

the Clark County Regional Transportation Commission. Each of these entities

has adequate personnel, funding and authority to implement their respective 

measure of the proposed primary control measures. 

On April 22, 1999, the Clark County District Board of Health adopted Section 54,

Cleaner Burning Gasoline, to the Air Pollution Control Regulations. The Regional 

Transportation Commission, at their June 10, 1999, meeting, adopted Resolution 

No. 177. The adoption of this resolution establishes TDM program guidelines to

mitigate traffic congestion and directs the RTC’s TDM Division to implement and 

monitor this program. Chapter 486A, of the Nevada Revised Statutes mandates 

alternative fuel vehicle acquisition, fuel usage and reporting requirements 

applicable to all governmental vehicles based in nonattainment areas. The 

Nevada Department of Conservation and Natural Resources, Division of 

Environmental Protection, via this legislation, is the agency responsible for 

administering this program. 

Additionally, the Nevada State Environmental Commission adopted a resolution 

on April 9, 1999, committing to adopting appropriate emission reduction 

measures as necessary to insure that ambient air quality standards can be 

achieved and maintained in the Las Vegas Valley. This action by the 

Commission serves to further insure that attainment will occur by December 31, 

2000. Copies of regulations and resolutions mentioned above can be found in 

Appendix D. 

Table 8-1 summarizes the implementation status of the primary control measures 

along with information on the agency responsible for implementing the respective

control measure. 

TABLE 8-1 

CONTROL MEASURE IMPLEMENTATION STATUS

Control Measure Implementation Date Responsible Agency 

Clean Burning Gasoline 1999 Health District 

Voluntary TCM/TDM Program 1999/Ongoing RTC 

Technician Training/Certification 1988 DMV&PS

Alternative Fuels Program for 

Government Fleets 1991/Ongoing NDEP/Govt. Entities

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 8-1 
8.2 SIP IMPLEMENTATION, MONITORING AND REPORTING 

This plan provides direction for attaining the national CO standard. To insure 

that attainment is reached, the progress associated with implementation of

controls and the resulting emission reductions must be monitored. In doing so, 

monitoring will indicate if implementation is on schedule or if implementation 

needs to be accelerated. This responsibility will be shared by the Clark County

Health District AQD, the State of Nevada Department of Environmental 

Protection, the Clark County Regional Transportation Commission and the Clark 

County Department of Comprehensive Planning. Monitoring will also assist in 

determining the effectiveness of control measures. VMT will be monitored 

through an annual VMT tracking report. This annual report will serve as the 

vehicle by which monitoring / tracking of controls are reported to the EPA.

Ambient air quality data will continue to be monitored through the monitoring

network described in Chapter 2 of this document. This network will continue to 

be operated in accordance with the federal requirements of 40 CFR Part 58 and 

quarterly reports will continue to be prepared and submitted to the EPA by the 

AQD. The Las Vegas Valley Air Quality Planning Committee will continue to

insure intergovernmental coordination, consensus building, and monitoring 

functions. 

 

8.3 MAINTENANCE 

The EPA requires that implementation plans also provide for the maintenance of 

the standard after it has been attained. Since the primary source of CO is the 

on-road mobile sources category, VMT projections for five years past the 

demonstration date have been forecasted (Table 8-2). These VMT projections

will be utilized in conjunction with the Mobile-UAM Modeling system as part of 

monitoring the effectiveness of control measures past the year 2000. It is 

anticipated that additional modeling will be a requirement of maintenance plan 

submittals for areas seeking redesignation. 

VMT contingency measures will be triggered after the year 2000 in the event 

actual VMTs exceed forecasts. The Las Vegas Valley Air Quality Implementation 

Plan will remain in effect following the attainment date until superseded by 

approval of a CO Maintenance Plan. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 8-2 
TABLE 8-2 

VMT ESTIMATES FOR MONITORING AND MAINTENANCE

Road Segment 2000 2001 2002 2003 2004 2005

External Connector 765,734 800,857 835,981 871,105 906,229 941,353

Freeway System Ramps 100,916 104,915 108,914 112,913 116,912 120,912

Minor Arterial 7,941,628 8,313,494 8,685,360 9,057,227 9,429,093 9,800,959

Major Arterial 3,809,224 3,923,028 4,036,831 4,150,635 4,264,438 4,378,242

Ramp 296,162 311,904 327,646 343,388 359,130 374,872

Interstate 4,079,915 4,249,168 4,418,422 4,587,675 4,756,929 4,926,182

Freeway 1,679,985 1,849,208 2,018,432 2,187,655 2,356,878 2,526,102

Expressway 293,698 299,422 305,147 310,871 316,595 322,319

Collector 3,389,942 3,693,134 3,996,327 4,299,519 4,602,711 4,905,904

Local 2,394,976 2,498,849 2,602,721 2,706,594 2,810,466 2,914,339

Intrazonal Trips 110,406 114,910 119,414 123,918 128,422 132,927

Public Transit 66,900 79,880 92,860 105,840 118,820 131,800

Daily Average Total 24,929,486 26,238,770 27,548,054 28,857,339 30,166,623 31,475,908

8.4 MOBILE SOURCES EMISSIONS BUDGET

Under the conformity provisions of the Clean Air Act, Section 176(c)(2)(A) 

requires regional transportation plans and programs to show that “emissions

expected from implementation of plans and programs are consistent with 

estimates from motor vehicles and necessary emission reductions contained in 

the applicable implementation plan.” On November 24, 1993 EPA issued

regulations defining how the provisions of 176(c) will work, including defining

mobile vehicle emission budgets in applicable SIPs. EPA conformity rule defines

motor vehicle emissions budgets as: 

“.... the explicit or implicit identification of the motor vehicle-related 

portions of the projected emission inventory used to demonstrate 

reasonable further progress milestones, attainment, or maintenance for a 

particular year specified in the SIP.”

The motor vehicle emissions budget therefore establishes a cap on motor

vehicle-related emissions which cannot be exceeded by predicted transportation 

system emissions in the future. The emissions budget applies as a ceiling on 

emissions in the year for which it is defined and for all subsequent years until 

another year for which a different budget is defined or until a SIP revision 

modifies the budget. 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 8-3 
Without a clearly indicated intent otherwise expressed in the SIP, the SIP’s

estimate of future transportation network emissions used in the milestone or 

attainment demonstration is the motor vehicle emissions budget. The SIP may 

also specify emissions budgets for subareas of the region, provided the SIP 

includes a demonstration that the subregional emissions budget, when combined 

with all other portions of the emissions inventory, will result in attainment and/or 

maintenance of the standard. 

The emissions analysis for conformity determinations must include emissions 

from the entire transportation network within the nonattainment area. Likewise, if 

the transportation and air quality modeling domains extend beyond the 

nonattainment area, the budget applies for the portion only within the 

nonattainment area boundary. In the case of Las Vegas, the nonattainment area 

encompasses both the air quality modeling domain (UAM) and the transportation 

planning domain. 

EPA’s conformity rule requires that air quality implementation plans contain an 

emissions budget. The emissions budget reflects the portion of emissions, by 

source category and year, which can be accommodated in the airshed without 

exceeding the NAAQS. The emissions budgets also reflect the effects that 

control measures will have in future years. 

Table 8-3 below provides a breakdown of the Las Vegas Valley Nonattainment 

Area’s attainment and future horizon year’s emission budgets.

TABLE 8-3 

LAS VEGAS VALLEY PEAK SEASON EMISSION BUDGETS 

by Source Category

Source Category 1996 2000 2010 2020

(Tons/Day) (Tons/Day) (Tons/Day) (Tons/Day)

On-road Motor Vehicles* 405.4 310.2 329.5 457.4

Area Sources 8.5 9.9 15.3 19.4

Point Sources 6.5 6.5 6.5 6.5

Non-road Sources excl. County Airports 22.3 20.1 18.2 19.3

County Airports 36.4 40.4 55.6 77.1

Total Budget 479.1 387.2 425.2 579.7

Maximum Predicted CO Concentration (ppm) 11.2 8.1 7.2 8.5

* On-Road Mobile Sources Budgets are adjusted for the Month of December (adjustment factor = 1.021)

CARBON MONOXIDE STATE IMPLEMENTATION PLAN 8-4 
CARBON MONOXIDE STATE IMPLEMENTATION PLAN 8-5 

8.5 ADDITIONAL COMMITMENTS TO INSURE CONFORMITY

The ability for Transportation Improvement Programs and Regional 

Transportation Plans to demonstrate conformity with this Air Quality Plan in 

future years is of utmost importance to State and local governmental agencies. 

To insure that a positive conformity determination can be made on the 

aforementioned transportation documents, this section constitutes an 

implementation plan commitment to promulgate regulations as provided for in the 

U.S. Environmental Protection Agency’s Transportation Conformity Rule (40 CFR 

51.452). 

Contained in the 1995 Carbon Monoxide Air Quality Implementation Plan, the 

commitment to remote sensing of 90% of all vehicles in the Las Vegas Valley by 

2011 was made by the Nevada Department of Motor Vehicles and Public Safety 

(DMV&PS). This commitment is carried forward with this plan so that an 

additional 5% emission reduction will take place. 

The additional commitment constitutes a control measure that will insure a 

positive conformity determination. Additionally, the Nevada State Environmental 

Commission adopted a Resolution at their meeting on April 9, 1999, committing 

to “adopting appropriate emission reduction measures as necessary to ensure 

that ambient air quality standards can be achieved and maintained in the Las 

Vegas Valley, and conformity between the Transportation Improvement Program 

and the State Implementation Plan can be demonstrated”. This commitment by 

the State Environmental Commission will provide additional emission reductions. 

A copy of the resolution and the commitment letter from Nevada DMV&PS is 

located in Appendix D, Section 7. 
References

1. Bohning, S. 1998. Letter to Clete Kus, Clark County Department of 

Comprehensive Planning, from the U.S. Environmental Protection Agency, 

Region IX, San Francisco, CA (October 27, 1998). 

2. Bowen, J.L. and R.T. Egami. 1994. “Clark County Carbon Monoxide Hotspot

Study”, Final report prepared for the Clark County Health District, DRI

Document NO. 6460-684-4010.1F1, Nov. 10, 1994. 

3. BRW and SAI. 1992. “Las Vegas Air Quality Implementation Plan Update, 

Phase II: Carbon Monoxide Modeling and Attainment Demonstration.” 

Prepared for the Clark County Department of Comprehensive Planning, by

BRW, Inc., San Diego, CA and Systems Applications, Inc., San Rafael, CA. 

4. CCDCP. 2000. Supplemental Urban Airshed Modeling Analysis for the Las 

Vegas Valley Carbon Monoxide Attainment Demonstration. 

5. CCDCP. 2000. Microscale Hot Spot Modeling with the CAL3HC for the Las

Vegas CO SIP. 

6. DRI, STI, and ENVIRON. 1996. “Modeling Protocol for the Las Vegas Valley

Carbon Monoxide Urban Airshed Modeling Project – Phase II: Field Data

Collection.” Prepared for the Clark County Department of Comprehensive

Planning, by the Desert Research Institute, Reno, NV., Sonoma Technology, 

Inc., Santa Rosa, CA, and ENVIRON International Corp., Novato, California. 

7. Egami, D., J. Bowen, P. Roberts, S. Reyes, T. Dye, C. Emery, D. Souten.

1998. “The Las Vegas Valley Carbon Monoxide Urban Airshed Model Update 

Project – Phase II: Field Data Collection.” Prepared for the Clark County 

Department of Comprehensive Planning, by the Desert Research Institute,

Reno, NV, Sonoma Technology, Inc., Santa Rosa, CA, and ENVIRON 

International Corporation, Novato, CA. 

8. Emery, C., J. Heiken, D. Souten. 1996. “Phase I Draft Final Report.”

Technical memorandum prepared for the Clark County Department of 

Comprehensive Planning, by ENVIRON International Corp., Novato,

California. 

________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN R-1 
References - Continued

9. Emery, C., D. Souten, N. Kumar, F. Lurmann, and P. Roberts. 1998. “The 

Las Vegas Valley Carbon Monoxide Urban Airshed Model Update Project – 

Phase II: UAM Base Case and Sensitivity Applications.” Prepared for the 

Clark County Department of Comprehensive Planning, by ENVIRON 

International Corporation, Novato, CA, and Sonoma Technology, Inc., Santa 

Rosa, CA. 

10. Emery, C., D. Souten. 1998. “Results of Revised Phase II Base Case CO

Modeling, and Recommendation of Episode Selection for Future Year

Assessments.” Technical memorandum prepared for Scott Bohning of the 

U.S. Environmental Protection Agency, Region IX, San Francisco, CA, by 

ENVIRON International Corp., Novato, CA. 

11. ENVIRON. 1996. “Modeling Protocol for the Las Vegas Valley Carbon

Monoxide Urban Airshed Model Update Project.” Prepared for the Clark 

County Department of Comprehensive Planning, by ENVIRON International 

Corp., Novato, California. 

12. EPA 1992. Guidelines for Regulatory Application of the Urban Airshed Model 

for Areawide CO Applications. EPA-450/4-92-011a&b, Research Triangle 

Park, NC. 

13. U.S. EPA. January 1992. Section 187 VMT Forecasting and Tracking

Guidance. 

14. EPA. 1997. “Guidance on Incorporating Voluntary Mobile Source Emission

Reduction Programs in State Implementation Plans (SIPs).” Memorandum to 

EPA Regional Administrators, from Richard D. Wilson, Acting Assistant 

Administrator for Air and Radiation (October 24, 1997). 

15. EPA. 1991. Emission Inventory Requirements for carbon Monoxide State 

Implementation Plans. U.S. EPA. Research Triangle Park, NC (EPA-450/4-

91-011). 

16. EPA. 1991. Final Draft, Section 187 VMT Forecasting and Tracking 

Guidance. 

17. EPA. 1988. Guidance for the Preparation of Quality Assurance Plans for 

O3/CO SIP Emission Inventory. EPA-450/4-88-023. 

________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN R-2 
________________________________________________________________ 

CARBON MONOXIDE STATE IMPLEMENTATION PLAN R-3 

References – Continued

18. EPA. 1991. Procedures for the Preparation of Emission Inventories for 

Carbon Monoxide and Precursors of Ozone, Volume I: General Guidance for 

Stationary Sources. EPA-450/4-91-016, Research Triangle Park, NC. 

19. EPA. 1991. Procedures for the Preparation of Emission Inventories for 

Carbon Monoxide and Precursors of Ozone, Volume II: Emission Inventory 

Requirements for Photochemical Air Quality Simulation Models. EPA-450/4-

91-014, Research Triangle Park, NC. 

20. EPA. 1991. Quality Review Guidelines for 1990 Base Year Emission 

Inventory. EPA-450/4-91-022, Research Triangle Park, NC. 

21. EPA. 1991. User’s Guide to MOBILE5. U.S. EPA, Ann Arbor, Michigan. 

22.Lima and Associates. 1998. “Carbon Monoxide Transportation Control 

Measures Analysis.” Prepared for the Clark County Department of 

Comprehensive Planning, by Lima & Associates. 

23. Environ, July 1999. “Dispersion Modeling of Carbon Monoxide Emissions 

 from Three Clark County Airports in Support of the Revised CO SIP”. 

 Prepared for the Clark County Department of Aviation, by ENVIRON 

 International Corp., Novato, California. 

24. Ricondo & Associates, 1999. “Carbon Monoxide Emissions Inventories and 

 Dispersion Modeling from McCarran International, North Las Vegas, and 

 Henderson Executive Airports” Prepared for Clark County, Department 

 of Aviation.