Nevada Air Quality Trend Report 

2000-2010

Nevada Division of Environmental Protection
Nevada Air Quality Trend Report, 2000-2010

i

Contents

Disclaimers................................................................................................................................................................................... ii

List of Tables............................................................................................................................................................................... iii

List of Figures.............................................................................................................................................................................. iii

Acronyms and Abbreviations...................................................................................................................................................... iv

Acknowledgements..................................................................................................................................................................... v

Executive Summary .................................................................................................................................................................... vi

1 Introduction ........................................................................................................................................................................ 1

1.1 Background ................................................................................................................................................................ 1

1.2 Nevada’s Air Monitoring Network ............................................................................................................................. 2

1.3 Attainment Status of Areas........................................................................................................................................ 5

1.4 Methodology for statistics analysis............................................................................................................................ 5

2 Criteria Pollutants............................................................................................................................................................... 6

2.1 National Ambient Air Quality Standards.................................................................................................................... 6

2.2 Carbon Monoxide....................................................................................................................................................... 7

2.2.1 National Carbon Monoxide Trend..................................................................................................................... 7

2.2.2 Carbon Monoxide Trends in NAPCP’s Monitoring Network.............................................................................. 8

2.3 Lead.......................................................................................................................................................................... 10

2.3.1 National Lead Trend ........................................................................................................................................ 10

2.4 Nitrogen Dioxide ...................................................................................................................................................... 12

2.4.1 National Nitrogen Dioxide Trend..................................................................................................................... 12

2.5 Ground-Level Ozone ................................................................................................................................................ 14

2.5.1 National Ground-Level Ozone Trend............................................................................................................... 15

2.5.2 Ozone Trends in NAPCP’s Monitoring Network .............................................................................................. 15

2.6 Particulate Matter.................................................................................................................................................... 18

2.6.1 National PM2.5 Trend ....................................................................................................................................... 19

2.6.2 PM2.5 Trends in NAPCP’s Monitoring Network................................................................................................ 20

2.6.3 National PM10 Trend........................................................................................................................................ 23

2.6.4 PM10 Trends in NAPCP’s Monitoring Network ................................................................................................ 23

2.7 Sulfur Dioxide........................................................................................................................................................... 28

2.7.1 National Sulfur Dioxide Trend ......................................................................................................................... 29

3 Appendixes ....................................................................................................................................................................... 30

3.1 Monitoring Station Description................................................................................................................................ 30

3.2 Monitoring Data Availability .................................................................................................................................... 48

3.3 Monitoring Data....................................................................................................................................................... 49
Nevada Air Quality Trend Report, 2000-2010

ii

Disclaimers

The information contained in the Nevada Air Quality Trend Report, 2000-2010 is for public use; every 

effort has been made to ensure its accuracy. The information presented is as timely and accurate as 

practicable; no expressed or implied guarantees are made. Information contained herein may be freely 

distributed and used for noncommercial, scientific, and educational purposes.

Inquiries made in reference to this report should be directed to:

Nevada Air Pollution Control Program

901 South Stewart Street, Suite 4001

Carson City, Nevada 89701-5249

Telephone: (775) 687-4670
Nevada Air Quality Trend Report, 2000-2010

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List of Tables

Table 1: Current National Ambient Air Quality Standards.............................................................................................6

Table 2: Total number of exceedances of the PM10 24-Hour Standard, between 2000 and 2010..............................26

Table 3: Carbon monoxide. Annual maxima (ppm) and number of exceedances for each NAAQS for the Long Street 

and Harvey’s Resort Hotel in the 2000-2010 period. ..................................................................................................51

Table 4: Ozone: 3- year average of the annual 4th- highest daily maximum value......................................................53

Table 5: PM10: 3-year average for annual mean and annual 98th percentile of 24-hour average..............................55

Table 6: Total number of exceedances of the PM10 24-Hour Standard, between 2000 and 2010..............................57

List of Figures

Figure 1: Location of NAPCP Monitoring Sites, 2000-2010, and NAPCP planning areas...............................................4

Figure 2: National average carbon monoxide trend from 1980 to 2010.......................................................................8

Figure 3: Carbon Monoxide (1-hour Average) for the Long St. and Harvey’s Resort Hotel monitoring stations.. ........9

Figure 4: Carbon Monoxide (8-hour Average) for the Long St. and Harvey’s Resort Hotel monitoring stations. .........9

Figure 5: National lead trend, 1980-2010....................................................................................................................11

Figure 6: National nitrogen dioxide trend, 1980-2010 ................................................................................................13

Figure 7: National ozone trend, 1980-2010.................................................................................................................15

Figure 8: Ground level ozone trend.............................................................................................................................16

Figure 9: Ground-level ozone trend.............................................................................................................................17

Figure 10: Design values for ground-level ozone ........................................................................................................17

Figure 11: National PM2.5 Trend, 2000-2010 based on seasonally-weighted average ................................................20

Figure 12: 24-hour 98th percentile trend for PM2.5. ....................................................................................................21

Figure 13: 24-hour 98th percentile trend for PM2.5, averaged over 3 consecutive years (i.e. the design values) ......21

Figure 14: Annual averages of PM2.5 concentrations...................................................................................................22

Figure 15: 3-year average of annual mean PM2.5 concentrations (i.e., the design values). ........................................22

Figure 16: National PM10 Trend, 2000-2010................................................................................................................23

Figure 17: Annual 1st-highest value (1st H) for PM10, based on the 24-hour average................................................25

Figure 18: Annual average for PM10 from active (above) and discontinued (below) monitors...................................27

Figure 19: Annual national average for SO2 from 1980 to 2010..................................................................................29
Nevada Air Quality Trend Report, 2000-2010

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Acronyms and Abbreviations

Nevada’s 15 Rural Counties:

Carson City, Churchill, Douglas, Elko, Esmeralda, Eureka, Humboldt, Lander, Lincoln, 

Lyon, Mineral, Nye, Pershing, Storey, and White Pine

AMSL Above Mean Sea Level

BAQP Bureau of Air Quality Planning

BAM Beta Attenuation Monitor

BTU British Thermal Unit

CAA Clean Air Act

CFR Code of Federal Regulations

CO Carbon Monoxide

DCNR Department of Conservation and Natural Resources

GDP/GSP Gross Domestic Product/Gross State Product

H2S Hydrogen Sulfide

IMPROVE Interagency Monitoring of Protected Visual Environments

NAAQS National Ambient Air Quality Standard

NAC Nevada Administrative Code

NDEP Nevada Division of Environmental Protection

NAPCP Nevada Air Pollution Control Program

O3 Ozone

Pb Lead

PM2.5 Particulate Matter less than 2.5 microns in diameter

PM10 Particulate Matter less than 10 microns in diameter

SLAMS State and Local Air Monitoring Station

SO2 Sulfur Dioxide

SPMS Special Purpose Monitoring Station

SSMS Special Study Monitoring Station

USEPA United States Environmental Protection Agency
Nevada Air Quality Trend Report, 2000-2010

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Acknowledgements

This Trend Report presents ambient air quality data collected by the State of Nevada and the California 

Air Resources Board. The Nevada Department of Conservation and Natural Resources (DCNR), Division 

of Environmental Protection (NDEP), Nevada Air Pollution Control Program (NAPCP) gratefully 

acknowledges the ambient monitoring data contributions of the California Air Resources Board, 

Monitoring and Laboratory Division. The cover photo is of the Big Smoky Valley in central Nevada; 

provided courtesy of Michelle Stamates of NDEP.
Nevada Air Quality Trend Report, 2000-2010

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Executive Summary

The primary purpose of NAPCP’s ambient monitoring network is to determine current and projected 

concentrations of ambient air pollutants within the state, ensure current resource management 

strategies are working properly, and to develop new measures by which the ambient air quality 

standards will continue to be attained.

NAPCP’s current active monitoring network consists of monitors located in the following towns:

 Carson City – PM10, PM2.5, CO, and O3

 Gardnerville – PM10, PM2.5, and O3

 Stateline – CO 

 Fernley – PM10, PM2.5, and O3

 Fallon – PM10, and O3

 Elko – PM10

 Pahrump – multiple sites with PM10

This report spans the monitoring period from 2000 to 2010. During this period, NAPCP monitored the 

following criteria pollutants and observed the following trends:

 Carbon Monoxide (CO): Ambient concentrations of CO have decreased and remained well 

below the current National Ambient Air Quality Standards (NAAQS);

 Ground-Level Ozone (O3): Ambient concentrations of O3 have remained steady and below the 

current 2008 NAAQS; 

 Particulate Matter ≤ 2.5 micrometers in diameter (PM2.5): Ambient concentrations of PM2.5

have trended upward in Gardnerville and are close to the NAAQS in Carson City and 

Gardnerville. NAPCP is in the process of analyzing samples to determine the cause(s) of the 

elevated levels. Ambient concentrations of PM2.5 have decreased in Fernley. 

 Particulate Matter ≤ 10 micrometers in diameter (PM10): PM10 monitoring conducted in Elko 

has shown no significant change in ambient concentrations. Monitoring conducted in Pahrump 

shows that annual concentrations of PM10 have decreased in most of the monitored locations 

and remain well below the annual standard. The 24-hour PM10 concentrations in Pahrump 

remain steady at or near the standard. However, the number of actual exceedances of the 24-

hour standard have been reduced, most of which occurred during uncontrollable high wind 

events. As a result, the design values for PM10 show no exceedances of the NAAQS in the past 5 

years.

It should be noted that USEPA is actively reviewing and revising several of the NAAQS. Generally, these 

reviews are resulting in revised standards that are more stringent. More stringent standards may affect 

the future attainment status within Nevada’s 15 Rural Counties. As a result, NAPCP will be required to 

expand the State’s monitoring network. 
Nevada Air Quality Trend Report, 2000-2010

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1 Introduction

1.1 Background

Clean air is a managed natural resource. Nevada Revised Statute (NRS) 445B.100 establishes public 

policy regarding air quality in Nevada. This statute states:

“It is the public policy of the State of Nevada . . . to achieve and maintain levels of air quality which will 

protect human health and safety, prevent injury to plant and animal life, prevent damage to property, 

and preserve visibility and scenic, esthetic and historic values of the state.”

The mission of the Nevada Division of Environmental Protection (NDEP), and the Nevada Air Pollution 

Control Program (NAPCP, which comprises the Bureau of Air Quality Planning, BAQP, and Bureau of Air 

Pollution Control, BAPC) is to protect and enhance the environment in order to sustain healthy 

ecosystems and contribute to a vibrant economy. Our mission is accomplished through reasonable, fair, 

and consistent implementation of State and Federal air quality rules and regulations, with emphasis on 

objective and impartial responsiveness to the needs of a growing population and industrial base.

Air pollution comes from a variety of sources. These include "stationary sources," such as factories, 

power plants, and smelters; smaller sources, such as dry cleaners and degreasing operations; "mobile 

sources," such as cars, trucks, buses, trains, and planes; and "natural sources," such as wildfires and 

windblown dust. 

The USEPA has set NAAQS for six principal pollutants, which are called "criteria" pollutants: carbon 

monoxide (CO), ground-level ozone (O3), particulate matter (PM2.5,with an aerodynamic size less than or 

equal to 2.5 microns, and PM10, with an aerodynamic size less than or equal to 10 microns), sulfur 

dioxide (SO2), nitrogen dioxide (NO2), and lead (Pb). There are two forms of the NAAQS – Primary and 

Secondary, and they are summarized in Table 2.1. Primary standards are designed to protect human 

health, including sensitive populations such as children and the elderly. Secondary standards provide

public welfare protection and are designed to protect against decreased visibility, damage to animals, 

crops, vegetation, and buildings. 

 

The primary purpose of NAPCP’s ambient monitoring network is to determine current and projected 

concentrations of ambient air pollutants within the state, ensure current resource management 

strategies are working properly, and to develop new measures by which the ambient air quality 

standards will continue to be attained.

This document summarizes the ambient air data collected for the 11-year period between 2000 and 

2010 from the NAPCP monitoring network in Nevada’s 15 Rural Counties.1 

 

1

Nevada’s 15 Rural Counties are Carson City, Churchill, Douglas, Elko, Esmeralda, Eureka, Humboldt, Lander, 

Lincoln, Lyon, Mineral, Nye, Pershing, Storey, and White Pine. Clark and Washoe counties operate and maintain 

monitoring networks separate from NAPCP and publish their findings independently.
Nevada Air Quality Trend Report, 2000-2010

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Review of long-term monitoring data reveals trends in the ambient air quality and provides feedback on 

the effectiveness of measures utilized for managing the air resource. 

NAPCP performs air monitoring throughout the state. The current active monitoring network consists of 

monitors located in the following towns:

 Carson City – PM10, PM2.5, CO, and O3

 Gardnerville – PM10, PM2.5, and O3

 Stateline – CO 

 Fernley – PM10, PM2.5, and O3

 Fallon – PM10, and O3

 Elko – PM10

 Pahrump – multiple sites with PM10, and one site with PM2.5

It should be noted that USEPA is actively reviewing and revising several of the NAAQS. Generally, these 

reviews are resulting in revised standards that are more stringent. More stringent standards may affect 

the future attainment status within Nevada’s 15 Rural Counties. As a result, NAPCP may be required to 

expand the State’s monitoring network. A brief discussion of all criteria pollutants under USEPA review is 

provided in Section 2.

1.2 Nevada’s Air Monitoring Network

NAPCP operates a network of monitoring stations across Nevada’s 15 Rural Counties as shown in Figure 

1.1. The monitors conform to all USEPA siting criteria and are situated to measure air quality in both 

rural and the urbanized portions of Nevada’s 15 Rural Counties. In addition, NAPCP maintains two 

meteorological stations, one in Carson City and one in Pahrump, to provide meteorological information 

for the monitoring conducted in these areas and to support stationary source permitting needs. 

Detailed descriptions of both active and discontinued air quality monitoring stations are provided in 

Appendix A. A comprehensive list of monitoring data availability at NAPCP-maintained monitoring 

stations is provided in Appendix B and monitoring data used in report preparation is in Appendix C. 

The monitoring conducted by NAPCP is established for the purposes of meeting federal monitoring 

requirements and for state informational and planning purposes. These two are categorized as: 1) State 

and Local Air Monitoring Stations (SLAMS); 2) Special Purpose Monitoring Stations (SPMS); and 3) 

Special Study Monitoring Stations (SSMS). SLAMS sites are federally required, long-term air quality 

monitoring stations. SPMS sites are typically established to determine the air quality in a smaller, 

localized area or to monitor on a temporary basis. These sites typically operate for six to 24 months, and 

are generally used to measure air quality in areas not previously monitored. They may also be

established to monitor the effects of a specific air pollution source or group of sources on the 

surrounding air quality. Some sites within the network contain monitors to address both SLAMS and 

SPMS. 

SLAMS monitoring is required once an area exceeds established county population thresholds. 

Monitoring for Pb, SO2 and NO2, was not conducted during this reporting period as the population-based 

thresholds were not reached in any of Nevada’s 15 Rural Counties. SPMS monitoring was also not 

conducted for these three pollutants.
Nevada Air Quality Trend Report, 2000-2010

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This report presents the results of air quality monitoring conducted by NAPCP from 2000 to 2010. 

Provided below is a summary of the pollutants monitored, their general trends, and a description of the 

conditions under which the pollutants are typically found at their highest concentration.

Carbon Monoxide (CO): NAPCP’s monitoring network shows that the highest concentrations of CO often 

occur in the winter during strong temperature inversions in basins surrounded by mountains. When 

temperature inversions occur, CO is trapped near ground level, causing elevated concentrations. 

Ambient concentrations of CO have decreased and remained well below the current NAAQS.

Ground-Level Ozone (O3): NAPCP’s monitoring network shows that ambient concentrations of O3 have 

remained steady and below the current 2008 NAAQS. O3 concentrations are typically affected by the 

quantity of pre-cursor gases (NOx and VOC’s), temperature, and amount of sunlight available during the 

summer.

Particulate Matter ≤2.5 micrometers (PM2.5): NAPCP’s monitoring network shows that ambient 

concentrations of PM2.5 have trended upward in Gardnerville. No significant upward/downward linear 

trends were observed in the other monitored locations, and NAAQS were met in all the years analyzed. 

However, both Carson City and Gardnerville were characterized by large fluctuations in PM2.5

concentrations, which occasionally resulted in the daily maximum observations to be above the 1997 

NAAQS and potentially could results in concentrations above the tighter 2006 NAAQS. NAPCP is in the 

process of analyzing samples to determine the cause(s) of the elevated levels. The highest 

concentrations of PM2.5 often occur in the winter during strong temperature inversions in basins 

surrounded by mountains. When temperature inversions occur, residential wood combustion is often at 

its peak and PM2.5 is trapped near ground level, causing increases in ambient concentrations. Thus PM2.5

trends may reflect the occurrence or absence of strong inversions during winter. However, these 

exceedance events in the daily maximum concentrations did not result in non-attainment conditions, as 

both 1997 and 2006 standard are defined as the average of 3 consecutive years.

Particulate Matter ≤10 micrometers in diameter (PM10): During this reporting period, many of the PM10

monitors in the NAPCP’s network were taken offline because measurements remained well below the 

PM10 NAAQS. PM10 monitoring conducted in Elko has shown no substantial change in ambient 

concentrations. Monitoring conducted in Pahrump shows that annual concentrations of PM10 have 

decreased in most of the monitored locations and remain well below the annual standard. The 24-hour 

PM10 concentrations in Pahrump remain steady at or near the standard. However, the number of actual 

exceedances of the 24-hour standard have been reduced, most of which occurred during uncontrollable 

high wind events. 

 
Nevada Air Quality Trend Report, 2000-2010

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Figure 1: Location of NAPCP Monitoring Sites, 2000-2010, and NAPCP planning areas.
Nevada Air Quality Trend Report, 2000-2010

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1.3 Attainment Status of Areas

NAPCP’s Ambient Air Monitoring Branch is responsible for air quality surveillance in Nevada’s 15 Rural 

Counties. In addition to NAPCP’s monitoring network, air quality monitoring is being conducted through 

the Interagency Monitoring of Protected Visual Environments (IMPROVE) network by federal land 

management agencies. At present, there are two active IMPROVE monitoring sites in Nevada; one 

located in the Jarbidge Wilderness Area in northeastern corner of the state and the other near the 

Lehman Caves Visitor Center in Great Basin National Park, along the eastern border of the state near 

Baker.

The NAAQS published by USEPA in 40 CFR Part 50 define the levels of air quality that USEPA has 

determined protect human health and welfare. An area is considered to be in nonattainment for a 

pollutant if it has violations for a particular NAAQS. Conversely, attainment areas are those where 

monitoring shows that no violation of the NAAQS have occurred. An area is considered unclassifiable if 

no monitoring has been conducted to determine its classification and NAAQS violations would not 

otherwise be expected. The extent of an area’s classification is defined by the Hydrographic Area 

boundaries as established in 1979 for the State of Nevada. The planning area boundaries are shown in 

Figure 1.1.

From 2000-2010, areas under the jurisdiction of NAPCP were classified as attainment or unclassifiable 

for all criteria pollutants, with one exception. The Nevada side of the Lake Tahoe Basin was designated

nonattainment for CO in 1978, while the rest of Tahoe Basin within NAPCP’s jurisdiction was designated 

attainment/unclassifiable.

2 On October 27, 2003, NAPCP requested redesignation and USEPA approved 

the request on December 15, 2003.

Clark and Washoe counties have their own independent ambient monitoring networks. Please check 

each county's web site for additional information.

1.4 Methodology for statistics analysis

Time-series of pollutant concentration from each monitor station were tested for the presence of linear

trend using non-parametric algorithms. In particular, the Mann-Kendall method was used to determine 

the significance of the trend and the Sen’s slope method (also known as Theil-Sen method) was used to 

obtain the magnitude (i.e., the slope) of the linear trend. These methods provide a much more robust 

analysis than the traditional parametric approaches and are less sensitive to outlier values. In general, a 

time-series was considered having a significant trend if the significance value was equal or less than 5% 

(i.e., the probability of erroneously assuming a significant trend under actual no-trend conditions is 

equal or less than 5%). However, as the 5% threshold is commonly used but somewhat arbitrary (as any 

other potential threshold), specific cases were discussed by reporting different significance levels as 

well. It is important to recognize that results from statistical analyses were largely limited by the number 

of data points available, and, still, by outliers. In this respect, results from these analyses should not be 

considered as absolute proof (or disproof) for the presence (or absence) of significance trends in the 

concentration datasets. 

 

2

The Nevada side of the Lake Tahoe Basin is formally known as Hydrographic Area 90 which includes portions of 

Carson City County, Douglas County, and Washoe County.
Nevada Air Quality Trend Report, 2000-2010

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2 Criteria Pollutants

2.1 National Ambient Air Quality Standards

The federal Clean Air Act (CAA), which was last amended in 1990, requires USEPA to set NAAQS for 

pollutants considered a danger to public health and welfare. The CAA established two types of NAAQS: 

Primary standards set limits to protect public health, including the health of sensitive populations such 

as children, the elderly, and asthmatics. 

Secondary standards set limits to protect public welfare, including protection against decreased 

visibility, damage to animals, crops, vegetation, and buildings.

Criteria pollutants are monitored with federal reference (FRM) or equivalent (FEM) methods that USEPA 

has approved. For each criteria pollutant, USEPA specifies the monitoring objectives that define the 

parameters by which health exposure and public welfare are assessed, and the measurement scale 

classifications that describe the influence of atmospheric movement at a given location. 

Table 1: Current National Ambient Air Quality Standards (http://www.epa.gov/air/criteria.html).

Pollutant Averaging time Form NAAQS -Primary NAAQS –Secondary

Carbon Monoxide (CO)

8-hour Not to exceed more than 

once per year

9ppm

N/A

1-hour Not to exceed more than 

once per year

35 ppm

Lead (Pb) Rolling 3-month Not to exceed, over a 

period of 3 years, 0.15 μg m-3

Same as primary

Nitrogen Dioxide (NO2)

1-hour

98th percentile of daily 

maximum distribution, 

averaged over 3 years, 

not to exceed

100 ppb N/A

Annual Mean Not to exceed 53 ppb Same as primary

Ozone (O3) 8-hour

Annual fourth-highest 

daily maximum, averaged 

over 3 years, not to 

exceed

0.075ppm Same as primary

Particle Pollution

≤2.5 μm (PM2.5)

Annual* Averaged over 3 year not 

to exceed 15 μg/m3

Same as Primary

24-hour 98th percentile, averaged 

over 3 year, not to exceed 35 μg/m3

Same as Primary

Particle pollution

≤10 μm (PM10)

24-hour

Not to exceed more than 

once per year, on average 

over 3 year

150 μg/m3Same as Primary

Sulfur Dioxide (SO2)

1-hour

99th percentile of daily 

maximum, averaged over 

3 years, not to exceed

75 ppb

3-hour Not to exceed more than 

once per year

0.5 ppm

*

The annual NAAQS for PM2.5 was revised from 15 μg/m3to 12 μg/m3in December 2012
Nevada Air Quality Trend Report, 2000-2010

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2.2 Carbon Monoxide

Carbon monoxide (CO) is a colorless, odorless, gas that is typically produced by the incomplete 

combustion of fuels. Compliance with the CO NAAQS is met when the 8-hour and the 1-hour average 

don’t exceed 9 ppm and 35 ppm, respectively, more than once per year. The CO NAAQS have not 

changed since they were originally promulgated in 1971; however, they are currently under USEPA 

review. 

NAPCP MONITORING NETWORK:

Between 2000 and 2010, NAPCP measured ambient concentrations of CO at 2 monitors:

 Long Street in Carson City: 2000-2009 (discontinued site)

 Harvey’s Resort Hotel in Stateline: 2000-2010

ATTAINMENT STATUS:

From 2000-2010, areas under the jurisdiction of NAPCP were classified as attainment or unclassifiable 

for CO except for the Nevada side of the Lake Tahoe Basin. This portion of the Basin was designated 

nonattainment for CO in 1978, while the rest of Tahoe Basin within NAPCP’s jurisdiction was designated 

attainment/unclassifiable. The nonattainment designation was based on monitoring conducted in 

Stateline during the 1970s. On October 27, 2003, NAPCP requested redesignation of the Nevada side of 

the Basin to attainment of the CO standards. NAPCP’s redesignation request for the Nevada side of the 

Lake Tahoe Basin was based on ambient air quality monitoring data that showed no violations for 

calendar years 2001 through 2002. On December 15, 2003, USEPA published a final rule 

(http://www.federalregister.gov/articles/2003/12/15/03-30369/approval-and-promulgation-ofimplementation-plans-state-of-nevada-designation-of-areas-for-air#p-48) effective February 13, 2004 

redesignating the Nevada side of the Lake Tahoe Basin attainment for CO.

2.2.1 National Carbon Monoxide Trend

Nationally, average CO concentrations have decreased substantially over the years. Based on the annual 

2

nd highest value of the 8-hour average, national CO average concentration decreased 82% from 1980 to 

2010 (Figure 2 and http://www.epa.gov/airtrends/carbon.html). From 2000 to 2010, national CO 

average concentration decreased 54%, with a significant trend (based on the Mann-Kendal and Sen’s 

slope statistics) of -0.2 ppm per year. The decrease in average CO concentrations is largely the result of 

improved pollution control technology in on-road vehicles that has significantly reduced CO emissions. 

Since 1970, CO emissions from on-road vehicles have been cut by more than 40 percent nationwide. 
Nevada Air Quality Trend Report, 2000-2010

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Figure 2: National average carbon monoxide trend from 1980 to 2010. The black dashed line is the average 2nd

highest value (based on the 8-hour averages) from 104 (1980-1989), 170 (1990-1999), and 265 (2000-2010) monitoring sites 

(http://www.epa.gov/airtrends/carbon.html). The blue area delimits the 10th and 90th percentile of the annual observation 

distributions. Red dotted line is the national standard (9 ppm). 

2.2.2 Carbon Monoxide Trends in NAPCP’s Monitoring Network

For the entire 2000-2010 period, ambient concentrations of CO (8-hour and 1-hour average) have 

trended downward and remained, in most cases, well below the NAAQS (Figure 3 Figure 4).

The Long Street monitor site in Carson City showed a significant downward trend in the 1st highest value 

of both the 8-hour and 1-hour average (-0.2 ppm per year and -0.6 ppm per year, respectively). In 

particular, the trend in the 1st highest value of the 8-hour average mirrored the 2nd-highest value of 8-

hour average national trend (Figure 2). Results from the Harvey’s Resort Hotel monitor in Stateline also 

show a downward trend in the 1st highest values of the 8-hour and 1-hour average, although less 

consistent trend. The peak in 2002 was observed during the July 2002 Gondola Fire; a timber wildfire 

that burned 673 acres at the Heavenly Ski Resort a short distance from the monitor. Trends at the 

Harvey’s Resort Hotel monitor site were not significant at the 5% confidence interval. However, they 

were significant at the 10% confidence interval, suggesting that a downward, though not very strong, 

trend existed. The 2nd-highest values of the 8-hour average are shown in Figure 4 as well. This is to 

confirm that while the highest 8-hour average CO concentration (8.8 ppm) went close to the NAAQS in 

2002 (9 ppm), the 2nd-highest value recorded in the same time series was well below that threshold (6.1 

ppm). 

0

2

4

6

8

10

12

14

16

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Concentration (ppm)

USA, 2nd Highest NAAQS
Nevada Air Quality Trend Report, 2000-2010

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Figure 3: Carbon Monoxide (1-hour Average) for the Long St. and Harvey’s Resort Hotel (HRH) 

monitoring stations. The 1st highest values, are shown for both monitor sites. NAAQS (35 ppm) is shown with a red dashed 

line.

Figure 4: Carbon Monoxide (8-hour Average) for the Long St. and Harvey’s Resort Hotel (HRH) 

monitoring stations. Annual 1st-highest values are shown for both stations, while annual 2nd-highest concentrations 

are shown for HRH only. The national average for annual 2nd highest concentration (as in Figure 2) is shown with a dashed 

black line. NAAQS (9 ppm) is shown with a red dashed line.

0

5

10

15

20

25

30

35

40

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Concentration (ppm)

Long St, 1st Max. HRH, 1st Max. NAAQS

0

1

2

3

4

5

6

7

8

9

10

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Concentration (ppm)

Long St, 1st Max. HRH, 1st Max. HRH, 2nd Max.

USA, 2nd Max. NAAQS
Nevada Air Quality Trend Report, 2000-2010

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2.3 Lead

Lead (Pb) is a metal found naturally in the environment. It is also mined and processed for use in 

manufactured products such as lead-acid batteries, old lead-based paint, ammunition, and gasoline.

From 1978 through 2008, the design value for Pb had been the calendar quarterly average, with a 

NAAQS established at 1.5 μg/m3. Effective January 12, 2009, US-EPA changed the design value to a 3-

month rolling average, evaluated over a 3 year period, and tightened both the primary and secondary 

NAAQS to 0.15 μg/m3. Therefore, compliance with the Pb NAAQS is met when daily concentrations

averaged for 3 adjacent months do not exceed 0.15 μg/m3over a period of 3 years.

NAPCP MONITORING NETWORK:

During the reporting period, NAPCP did not conduct ambient monitoring for Pb because monitoring 

thresholds established by USEPA have not been met in any of Nevada’s 15 Rural Counties. In addition, 

the revised NAAQS now require Pb monitoring near sources such as industrial facilities that emit onehalf ton or more of Pb per year and in Core Based Statistical Areas (CBSA) with populations greater than 

500,000.3In Nevada’s 15 Rural Counties there are no sources that emit one-half ton or more of Pb per 

year and no CBSA’s with populations greater than 500,000.

ATTAINMENT STATUS:

US-EPA designed all areas in Nevada’s 15 Rural Counties as unclassifiable, since NAPCP is not required to 

monitor for lead and these areas are expected to be meeting the 2008 NAAQS 

(http://www.epa.gov/leaddesignations/2008standards/final/region9f.html).

2.3.1 National Lead Trend

Nationally, average Pb concentrations have decreased substantially over the years. From 1980 to 2010 

there was an 89% decrease in the national Pb average, based on the same 31 monitor sites measured 

during the 1980-1989 period. From 2000 to 2010, there was a 61% reduction in the national Pb average, 

based on 92 monitor sites. The reduction in average Pb concentrations is mainly the result of removing

Pb from gasoline used in on-road vehicles, and additional source control programs for stationary sources 

in those areas that did not meet the national standards (http://www.epa.gov/airtrends/lead.html).

 

3

Core Based Statistical Area (CBSA) is a United States Census Bureau term that became effective in 2000 and refers 

collectively to metropolitan and micropolitan statistical areas. The 2000 census criteria provide that each CBSA 

must contain at least one urban area of 10,000 or more people. Each metropolitan statistical area must have at 

least one urbanized area of 50,000 or more inhabitants. Each micropolitan statistical area must have at least one 

urban cluster of at least 10,000 but less than 50,000 people.
Nevada Air Quality Trend Report, 2000-2010

11

Figure 5: National lead trend, 1980-2010. The black dashed line is the annual 1st-highest value (i.e., the annual 

maximum) based on 3-month average from 31 (1980-1989), 62 (1990-1999), and 92 (2000-2010) monitoring sites 

(http://www.epa.gov/airtrends/lead.html). The blue area delimits the 10th and 90th percentile of the annual observation 

distributions. Red dotted line is the 2008 national standard (0.15 ppm).

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Concentration (ppm)

USA, 3-Month Average, Annual Max NAAQS
Nevada Air Quality Trend Report, 2000-2010

12

2.4 Nitrogen Dioxide

Nitrogen dioxide (NO2) belongs to a group of reactive gases known as nitrogen oxides.4 Other nitrogen 

oxides include nitric oxide (NO) and nitrous oxide (N2O). In the environment NO2 is the predominant

form.5 NO2 forms rapidly, primarily resulting from fuel combustion sources.

The NO2 standard was first established in 1971 and defined attainment conditions when the average 

annual concentration does not exceed 53 ppb (or 0.053 ppm).

6

Effective April 12, 2010, USEPA 

established a new 1-hour based primary NAAQS. Compliance with the 1-hour standard is achieved when 

3-year average of the 98th percentile of the daily maximum distribution (1-hour average) does not 

exceed 100 ppb (or 0.1 ppm). 

NAPCP MONITORING NETWORK:

NAPCP does not currently monitor for NO2. Historical NO2 monitoring at Stateline and Carson City was 

terminated in 1997 due to very low monitored concentrations. During the reporting period, NAPCP did 

not conduct ambient monitoring for NO2 because monitoring thresholds established by USEPA have not 

been met in any of Nevada’s Rural Counties.

ATTAINMENT STATUS:

USEPA has designated all areas in Nevada’s 15 Rural Counties as unclassifiable, based on the 2010 

standards (http://www.epa.gov/no2designations/region/region9.html).

2.4.1 National Nitrogen Dioxide Trend

Nationally, average NO2 concentrations have decreased substantially over the years. From 1980 to 2010

there was a 52% decrease in the national NO2 average (based on the annual arithmetic average and on 

the 81 monitoring sites initially established in the 1990-1999 period). From 2000 to 2010, there was a 

38% reduction in the national NO2 average (based on 283 monitoring sites). The decrease in average 

NO2 concentrations is largely the result of improved pollution control technology in on-road vehicles 

that has significantly reduced NO2 emissions. Moreover, NO2 concentrations are expected to continue to 

decrease as a result of a number of new mobile source regulations

(http://www.epa.gov/airtrends/nitrogen.html).

 

4

Nitrogen oxides are also referred to as oxides of nitrogen.

5

NO2 is the monitored indicator for the larger group of nitrogen oxides.

6

The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the purpose 

of clearer comparison to the 1-hour standard.
Nevada Air Quality Trend Report, 2000-2010

13

Figure 6: National nitrogen dioxide trend, 1980-2010. The black dashed line is the annual arithmetic average based 

on 81 (1980-1989), 150 (1990-1999), and 283 (2000-2010) monitoring sites (http://www.epa.gov/airtrends/nitrogen.html). The 

blue area delimits the 10th and 90th percentile of the annual observation distributions. Red dotted line is the nation standard (53 

ppm).

0

10

20

30

40

50

60

70

Concentration (ppm)

Annual Arithmetic Average NAAQS
Nevada Air Quality Trend Report, 2000-2010

14

2.5 Ground-Level Ozone

Ozone (O3) in different layers of the atmosphere (i.e., ground-level O3 versus stratospheric O3) exhibits 

different effects. While the physical substance remains the same, ground-level O3 affects humans

adversely and therefore is considered a harmful pollutant. On the other hand, stratospheric O3 is 

essential to human survival and prevents harmful ultraviolet solar radiation from reaching the earth's 

surface. Ground-level ozone is a reactive, oxidant gas and is the primary constituent of photochemical 

smog. O3 is formed by reactions between nitrogen oxides and volatile organic compounds (VOCs) in the 

presence of sunlight. The actual photochemical reaction that produces O3 can take place far away from 

where the precursor gases are emitted. In addition, natural sources such as vegetation, soil, wildfires, 

and lightning emit nitrogen oxides and VOCs that lead to the formation of O3. Another source of 

localized O3 is downward mixing of O3 from the stratosphere, known as stratospheric O3 intrusion

(especially at high mountain locations).

The O3 NAAQS was first established in 1979 and based on hourly average concentrations. Primary and 

secondary standards were met when the number of days per calendar year with maximum hourly 

average concentrations above 0.12 ppm was less than or equal to 1. In 1997 USEPA created new primary 

and secondary O3 standards, based on the 8-hour average and set at 0.08 ppm. These standards are met 

when the 3-year average of the annual 4

th

-highest value of daily maximum distribution is less than or 

equal to 0.08 ppm. On June 15, 2005, USEPA revoked the 1-hour O3 standard established in 1979. 

Effective May 27, 2008, USEPA tightened the primary and secondary 8-hour O3NAAQS from 0.08 ppm to 

0.075 ppm7.

USEPA is pursuing a review of the O3 NAAQS on its normal 5 year review cycle. A proposed rule is 

expected to be released by the end of 2013 (http://www.epa.gov/glo/actions.html).

NAPCP MONITORING NETWORK:

Between 2000 and 2010, NAPCP measured ambient concentrations of O3 at 7 monitors:

 Fifth Street in Carson City: from 2008

 Long Street in Carson City: 1998-2007 (discontinued site)

 West End Elementary School in Fallon: from 2005

 Fire Station in Fernley: 1998-2003 (discontinued site)

 Intermediate School in Fernley: from 2007

 Cave Rock State Park in Zephyr Cove: 1999-2004 (discontinued site)

 IMPROVE Site in Great Basin National Park: from 19988

ATTAINMENT STATUS:

All areas within Nevada’s 15 Rural Counties are currently designated attainment/unclassifiable for the 

1997 1-hour O3 NAAQS and the 2008 8-hour O3 NAAQS 

(http://www.epa.gov/ozonedesignations/2008standards/final/region9f.htm). 

 

7

For more information on the history of O3 regulation, visit USEPA’s webpage: Ozone & Health – A Timeline.

8

Great Basin National Park IMPROVE monitoring site is maintained by the National Park Service.
Nevada Air Quality Trend Report, 2000-2010

15

2.5.1 National Ground-Level Ozone Trend

Nationally, average ground-level O3 showed a decline of 29% from 1980 to 2010 (based on the annual 

4

th

-highest value of the 8-hour average, Figure 7 and http://www.epa.gov/airtrends/ozone.html), with a 

significant trend of -0.817 ppb/year. The 2000-2010 period showed the largest rate in concentration 

decline, 60% larger than the one observed in the 1980-1999 period (-1.21 ppb/year and -0.75 ppb/year 

for 2000-2010 and 1980-1999, respectively). However, it’s only in 2004 that the national O3 average 

concentration fell below the 2008 NAAQS (0.075 ppm) for the first time. Across the United States, 

programs have been and are being implemented to reduce NOx and VOCs emissions from motor 

vehicles, industrial facilities, and power plants. VOCs emissions are used as a surrogate for O3 since O3 is 

not directly emitted by sources. Mitigation strategies also include reducing the emission of O3 precursor 

gases by reformulating fuels as well as consumer/commercial products such as paints and chemical 

solvents that contain VOCs.

Figure 7: National ozone trend, 1980-2010. The black dashed line is the annual 4th highest value of the 8-hour 

average concentration based on 247 (1980-1989), 507 (1990-1999), and 946 (2000-2010) monitoring sites 

(http://www.epa.gov/airtrends/ozone.html). The blue area delimits the 10th and 90th percentile of the annual observation 

distributions. Red dashed line is the current 8-hour national standard (0.075 ppm, accordingly to the 2008 NAAQS). From 1997 

to 2008, the 8-hour NAAQS was 0.080 ppm. From 1979 to 1997, only the 1-hour NAAQS was used.

2.5.2 Ozone Trends in NAPCP’s Monitoring Network

Because of the multiple historical changes in O3 NAAQS, trends based on both the 1-hour and 8-hour 

standards are presented in this report for all the monitor stations. For the 2000-2010 period ambient 

concentrations of ground-level O3 have remained relatively constant and below the revoked 1-hour 

based NAAQS in all active and discontinued stations (Figure 8). The only exceptions are the sites located 

at the Cave Rock State Park (discontinued in 2005) and Fifth St in Carson City (active from 2008), which 

both showed noticeable concentration reductions during the monitored periods 

The time-series of the annual 4th-highest daily maximum (based on the 8-hour average) and its 3-year 

average (the design value) fell below the NAAQS (pre- and after-2008 threshold) in all monitor sites 

(Figure 9 and Figure 10). In 2010, the highest concentrations were observed at the Great Basin National 

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Concentration (ppm)

8-hour average, 4th highest 2008 NAAQS (current)
Nevada Air Quality Trend Report, 2000-2010

16

Park. A study is currently being conducted by NDEP-NAPCP and University of Nevada in Reno to 

investigate the causes for such high O3 concentrations in the area9.

USEPA is pursuing a review of the O3 NAAQS on its normal 5 year review cycle. A proposed rule is 

expected to be released by the end of 2013 (http://www.epa.gov/glo/actions.html) and it may result in 

lower O3 NAAQS. 

Figure 8: Ground level ozone trend. The annual 1st highest values from hourly average concentrations are shown. Red 

dashed line is the National Standard (0. 12ppm), which was revoked by US-EPA in June 2005.

 

9

“Nevada Rural Ozone Iniziative” – Principal Investigator: Dr. Mae Gustin – Department of Natural Resources and 

Environmental Sciences, UNR

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

Concentration (ppm)

Fifth St. West End Element. Sch. Fernley Intermed. Sch.

Great Basin Ntnl Park Long St. Fernley Fire Stat.

Cave Rock State Park NAAQS
Nevada Air Quality Trend Report, 2000-2010

17

Figure 9: Ground-level ozone trend. The annual 4th-highest daily maximum from the 8-hour averages are shown. The 

red dashed line is the National Standard, which was revised from 0.08 ppm to 0.075 ppm in May 2008. Black dashed line is the 

national average (see also Figure 7).

Figure 10: Design values for ground-level ozone (3-year average of the annual 4th-highest daily maximum, based on 

the 8-hour average, as in Figure 8). Red dotted line is the National Ambient Air Quality Standard, which was revised from 0.08 

ppm to 0.075 ppm in May 2008.

0.050

0.055

0.060

0.065

0.070

0.075

0.080

0.085

Concentration (ppm)

Fifth St. West End Element. Sch. Fernley Intermed. Sch.

Great Basin Ntnl Park Long St. Fernley Fire Stat.

Cave Rock State Park NAAQS

0.050

0.055

0.060

0.065

0.070

0.075

0.080

0.085

99-01 00-02 01-03 02-04 03-05 04-06 05-07 06-08 07-09 08-10 09-11

Concentration (ppm)

Fifth St. West End Element. Sch. Fernley Intermed. Sch.

Great Basin Ntnl Park Long St. Fernley Fire Stat.

Cave Rock State Park USA NAAQS
Nevada Air Quality Trend Report, 2000-2010

18

2.6 Particulate Matter

Particulate matter (PM) generally consists of a mixture of particles of dust, pollen, ash, soot, metals and 

other various solid and liquid chemicals found in the atmosphere.10 There are two categories of particle 

matter pollutants: PM2.5 and PM10. PM2.5 (also known as “fine particulate”) is particulate matter 2.5 

microns or smaller in aerodynamic diameter. PM10 (also known as “inhalable coarse particulate”) is 

particulate matter 10 microns or smaller in aerodynamic diameter. For reference, ten microns is about 

one-seventh the diameter of human hair. 

PM2.5 can be directly emitted from sources such as fires, construction sites, residential wood 

combustion, or unpaved roads. PM10 emissions are from sources such as seas salt, unpaved roads, 

construction/demolition dust, and rock processing. These particles are referred to as primary particles, 

as they are directly emitted by the sources. PM2.5 and PM10 can also form as the result of the interaction 

of gaseous pollutants (such as SO2, NOx, and VOCs, emitted, among others, from power plants, 

industries and automobiles) in the atmosphere. These particles are referred to as secondary particles.

Given the small size, PM2.5 can remain suspended in the air and be transported extremely long distances. 

Meteorological conditions (e.g., inversion, rain, wind) can have a significant effect on ambient 

particulate concentrations. 

USEPA first issued standards for total suspended particles in 1971 and revised them in 1987 (for PM10

only), 1997 (for PM10 and PM2.5), 2006 and 2012. 

PM2.5: In September 1997, new standards were established, based on 24-hour and annual averages. The 

24-hour average-based NAAQS is met when the 98th percentile of the annual distribution, averaged over 

3 years, does not exceed 65 μg/m3. The annual NAAQS is met when the 3-year average of the annual 

weighted mean concentration is less or equal to 15 μg/m3. In December 2006, USEPA tightened the 24-

hour PM2.5 NAAQS from 65 μg/m3to 35 μg/m3. In December 2012, the annual-average-based primary 

standard was tightened from 15 μg/m3to 12 μg/m3.

PM10: new standards were established in 1987, based on 24-hour and annual averages. The annualbased NAAQS is met when the 3-year average of the 98th percentile 24-hour concentration is less than 

or equal to 50 μg/m3. The annual NAAQS was revoked in 2006. The primary and secondary 24-hour PM10

NAAQS are met when the expected number of days per calendar year above 150 μg/m3is less than or 

equal to one, over a 3-year period.

NAPCP MONITORING NETWORK:

Between 2000 and 2010, NAPCP measured ambient concentrations of PM2.5 at 5 monitor sites:

 Fifth Street in Carson City: 2009-2010 (special study monitoring station)

 Long Street in Carson City: 2000-2009 (discontinued)

 Intermediate School in Fernley: 2000-2010

 Gardnerville Ranchos in Gardnerville: 2000-2010

 Cave Rock State Park in Zephyr Cove: 2000-2001 (discontinued)

 

10 The majority of compounds that form particle pollution can be grouped into five categories: sulfates, nitrates, 

elemental carbon, organic carbon, and “crustal” material.
Nevada Air Quality Trend Report, 2000-2010

19

The Fifth Street, Gardnerville Ranchos, and Fernley Intermediate School monitors are maintained within 

NAPCP’s network for special study purposes.

Between 2000 and 2010, NAPCP measured ambient concentrations of PM10 at 10 monitor sites:

 High School in Battle Mountain: 2000-2002 (discontinued)

 State Offices Building in Elko: 2000-2008 (discontinued)

 Grammar School No. 2 in Elko: 2008-2010

 Community Pool in Pahrump: 2001-2004 (discontinued)

 Linda Street in Pahrump: 2004-2010

 Willow Creek in Pahrump: 2004-2009 (discontinued)

 Church in Pahrump: 2004-2010

 Glenoaks Street in Pahrump: 2009-2010

 Manse Elementary School in Pahrump: 2005-2010

 Cave Rock State Park in Zephyr Cove (Lake Tahoe): 2000-2001 (discontinued)

The Community Pool site in Pahrump was relocated to the Manse Elementary School site because the 

site location did not conform to USEPA siting criteria and for a lack of continued maintenance access. 

ATTAINMENT STATUS:

On April 5, 2005, USEPA designated all areas within Nevada’s 15 Rural Counties as 

attainment/unclassifiable for the 1997 24-hour and annual PM2.5 NAAQS. On December 13, 2009, USEPA 

designated all areas within Nevada’s 15 Rural Counties as attainment/unclassifiable for the revised 2006 

24-hour PM2.5 NAAQS. On November 15, 1990, USEPA designated all areas within Nevada’s 15 Rural 

Counties as unclassifiable for PM10. 

Beginning in 2001, NAPCP began special purpose monitoring in the Pahrump Valley in Nye County. This 

monitoring indicated exceedances of the PM10 NAAQS (Figure 17 and Table 2). To correct the problem 

USEPA, NAPCP, the Pahrump Town Board, and Nye County agreed to implement control measures 

throughout the valley to address the exceedances. The measures generally are targeted at decreasing 

the sources and causes for PM emissions, such as increasing the fraction of paved roads, land 

disturbance mitigation, and dust control enforcement. Continued monitoring in the area indicates that 

the implemented control strategies have resulted in significant reductions in the number of monitored 

PM10 exceedances (Figure 17 and Table 2). Remaining exceedances are attributed to uncontrollable 

high-wind events, or “exceptional events”. The NDEP has submitted evidence of these exceptional 

events to the USEPA and is awaiting EPA’s concurrence.

2.6.1 National PM2.5 Trend

Nationally, average PM2.5 concentrations have significantly decreased since 2000 (Figure 11, and 

http://www.epa.gov/airtrends/pm.html). From 2000 to 2010 there was a 27% decrease in the national 

PM2.5 average, based on the seasonally-weighted average and 646 sites. The reduction in average PM2.5

concentrations is mainly the result of regional and national rules that have been and are being 

implemented to reduce emissions of pollutants that form PM2.5. In addition, a number of voluntary 

programs also are helping to reduce PM2.5 pollution 

(http://www.epa.gov/air/particlepollution/reducing.html). 
Nevada Air Quality Trend Report, 2000-2010

20

Figure 11: National PM2.5 Trend, 2000-2010 based on seasonally-weighted average (black dashed line) and 646 sites 

(http://www.epa.gov/airtrends/pm.html). National monitoring of PM2.5 started in 1999. The 2006 NAAQS for annual-average is 

shown as a reference (15 μg/m3, red dashed line). The blue area delimits the 10th and 90th percentiles of the distribution of 

annual values reported by the monitor sites nationwide.

2.6.2 PM2.5 Trends in NAPCP’s Monitoring Network

PM2.5 trends across the state showed high degree of variability (Figure 12, Figure 13,Figure 14, Figure 15)

and likely reflect localized conditions such as wintertime temperature inversions. The time-series of the 

98th percentile of the annual 24-hour average distribution (Figure 12) do not present any significant 

trend. However, the monitor stations on Long St. (Carson City) and at Gardnerville Ranchos 

(Gardnerville) showed a substantial peak in 2005. Even though the 2005 values in these locations 

exceeded the 1997 NAAQS, attainment conditions were met, as the 24-hour-based USEPA NAAQS for 

PM2.5 is defined as the average of three consecutive years (Figure 13). Under this definition, none of the 

stations reported values higher than the implemented NAAQS (Figure 13).

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Concentration (μg m-3

)

Annual Average NAAQS
Nevada Air Quality Trend Report, 2000-2010

21

Figure 12: 24-hour 98th percentile trend for PM2.5. The NAAQS are shown as a reference as well. However, 

exceedance events in these time-series do not indicate non-compliant conditions, as both 1997 and 2006 standard are defined 

as the average of 3 consecutive years (as in Figure 13).

Figure 13: 24-hour 98th percentile trend for PM2.5, averaged over 3 consecutive years (i.e. the design 

values). The NAAQS are shown as well. Design values for monitors in Cave Rock State Park are not shown, as less than 3 

consecutive years of data were available. 

0

10

20

30

40

50

60

70

80

Concentration (μg m-3

)

Long St. Fernley Intermed. Sch. Gardnerville Ranchos

Fifth St. Cave Rock State Park NAAQS

0

10

20

30

40

50

60

70

80

Concentration (μg m3

)

Long St. Fernley Intermed. Sch. Gardnerville Ranchos

NAAQS Fifth St.
Nevada Air Quality Trend Report, 2000-2010

22

The annual average time-series present similar results (Figure 14), with all but one station showing no 

significant trends. The exception is represented by the Gardnerville Rancho station, where a positive 

trend of approximately 0.7 μg/m3is detected. Annual and 3-year-averaged values are well below the 

1997 NAAQS (15 μg/m3). However, if the 2012 NAAQS are applied (12 μg/m3), annual values are above 

the threshold in 2010 (Figure 14), though the 3-year average would maintain attainment (Figure 15).

Figure 14: Annual averages of PM2.5 concentrations. The 1997 NAAQS (15 μg/m3) is shown as well.

Figure 15: 3-year average of annual mean PM2.5 concentrations (i.e., the design values). The 1997 NAAQS 

(15 μg/m3) is shown as well. Cave Rock State Park stations is not shown, as less than 3 consecutive years of data were available.

0

2

4

6

8

10

12

14

16

Concentration (μg m-3

)

Long St. Fernley Intermed. Sch. Gardnerville Ranchos

Fifth St. Cave Rock State Park NAAQS

0

5

10

15

Concentration (μg m3

)

Long St. Fernley Intermed. Sch. Gardnerville Ranchos

Fifth St. NAAQS
Nevada Air Quality Trend Report, 2000-2010

23

2.6.3 National PM10 Trend

Nationally, average PM10 concentration has decreased significantly over the years. From 1990 to 2010 

there was a 38% decrease in the national PM10 average (based on 279 sites). From 2000 to 2010, the 

reduction in concentration was 29%, based on 601 sites (Figure 16 and 

http://www.epa.gov/airtrends/pm.html). The reduction in average PM10 concentrations is mainly the 

result of regional and national rules that have been and are being implemented to reduce emissions of 

pollutants that form PM10. In addition, a number of voluntary programs also are helping to reduce PM10

pollution (http://www.epa.gov/air/particlepollution/reducing.html).

Figure 16: National PM10 Trend, 2000-2010 based on the annual 2nd highest value of the 24-hour average and 279 

sites (1990-1999) and 601 sites (2000-2010, http://www.epa.gov/airtrends/pm.html). National monitoring of PM10 started in 

1990. Black dashed line is the average from all the sites nationwide, and blue area delimits the 10th and 90th percentiles of the 

data distribution. Red dashed line is the National Ambient Air Quality Standard (150 μg m

3

). The addition of 322 new sites in 

2000 caused an increase in average PM10 concentration. This increase is likely due to a better representation of PM10

concentration across the Country.

2.6.4 PM10 Trends in NAPCP’s Monitoring Network

PM10 measurements are typically influenced by local conditions and often by “exceptional 

meteorological evens”, such as high-winds. For this reason, annual mean concentrations provide a good 

indicator of ambient PM10 trends and they are here presented together with the 24-hour averages (used 

with the NAAQS).

In general, 24-hour concentrations of PM10 in Elko, Battle Mountain and Lake Tahoe have remained

below the standard, with very few exceptions (Figure 17). Based on PM10 NAAQS, which require a 3-year 

average period, all of these sites met the requirements for attainment (Table 2). None of these sites 

present significant linear trend in the annual averages or were not active long enough to allow statistical 

analysis (Figure 18). Monitor sites in Pahrump showed 24-hour concentrations above the NAAQS at the 

0

20

40

60

80

100

120

140

160

180

1990

1991

19921993199419951996199719981999

2000

2001

20022003200420052006200720082009

2010

Concentration (μg m3

)

Annual Average (279 sites) Annual Average (601 sites) NAAQS
Nevada Air Quality Trend Report, 2000-2010

24

Manse Elementary School, Willow Creek, and Community Pool stations (Figure 17 and Table 2). 

However, the Community Pool site was relocated to the Manse Elementary School site because the site 

location did not conform to USEPA siting criteria and for a lack of continued access.

Strong linear trends are detected in the annual average time-series of several of these sites. The Church 

station showed a trend of about -1.3 μg/m3per year. The site at the Manse Elementary School showed a 

decline of about -4.7 μg/m3per year; this trend, while not significant at the 5% confidence interval, is 

significant at the 10% confidence interval. 

The apparent contradiction between the observed strong decline in concentrations and low statistical 

significance of the trend is likely due to the choice of the statistical approach and overall number of data 

points, rather than lack of trend in the observations. The Mann-Kendall algorithm is quite robust 

towards outliers (or spikes) in the dataset. The Manse ES time-series presents a strong decline in 

concentrations between 2005 (i.e. the first point of the series) and 2006, and a more consistent, but 

weaker, downwards trend thereafter (Figure 18). It is quite possible that the Mann-Kendall algorithm 

‘underestimated’ the effect of the 2005-2006 decline in the time-series, therefore decreasing the 

confidence level of the overall detected linear trend. A re-analysis of the time-series using a more 

standard parametric, but less robust approach, revealed a significant linear trend. The Manse ES station 

is currently active, and it is likely that the addition of more data points from more recent years may help 

in determining the actual pattern of the trend. A similar situation was found at the Willlow Creek site; a 

strong decline in PM10 concentration was observed in the last year of monitoring (2009), following a 

somewhat weaker downwards trend in the previous 4 years (Figure 18). Given the relatively short 

period the station was active (5 years), the statistical procedure failed in detecting a linear trend, even 

though it is very likely that an improvement in air quality occurred. 

The station on Linda St. is the only station in Pahrump that displayed a significant positive trend of about 

2.5 μg/m3per year. As explained earlier in this report, USEPA NAPCP, the Pahrump Town Board, and 

Nye County have been implementing control measures throughout the valley to address the high PM10

concentrations measured in this area. Continued monitoring in the area indicates that the implemented 

control strategies have resulted in significant reductions in the number of monitored PM10 exceedances 

(Figure 17 and Table 2). Remaining exceedances are attributed to uncontrollable high-wind events, or 

“exceptional events”. The NDEP has submitted evidence of these exceptional events to the USEPA and 

are awaiting EPA’s concurrence.
Nevada Air Quality Trend Report, 2000-2010

25

Figure 17: Annual 1st-highest value (1st H) for PM10, based on the 24-hour average. The 2nd-highest values 

(2nd H.) are shown for those stations where the 1st highest is above the NAAQS (red dashed line, 150 μg m

3

). The design value 

is defined as the average number of times that the 24-hour average exceeds the NAAQS over 3 years. To comply with the 

NAAQS, this number cannot exceed 1.

The following acronyms were used for the stations:

Elko Grammar School #2 : Elko GS #2 Battle Mountain High School: BM HS Willow Creek: WC

Manse Elementary School: Manse ES State Office Buildings: SOB Community Pool: CP

Cave Rock State Park: Cave Rock SP

Active Monitors

Discontinued Monitors

0

20

40

60

80

100

120

140

160

2004 2006 2008 2010

Concentration (

μg m-3

)

Elko GS #2 Linda St.

Church NAAQS

0

20

40

60

80

100

120

140

160

2004 2006 2008 2010

Concentration (μg m-3

)

Manse ES - 1st H. 2nd H.

Glenoaks St.

0

50

100

150

200

250

300

2000 2002 2004 2006 2008

Concentration (μg m-3

)

BM HS - 1st H. 2nd H.

WC - 1st H. 2nd H.

0

50

100

150

200

250

300

350

400

2000 2002 2004 2006 2008

Concentration (μg m-3

)

SOB - 1st H. 2nd H.

CP - 2nd H. 2nd H.

Cave Rock SP
Nevada Air Quality Trend Report, 2000-2010

26

Table 2: Total number of exceedances of the PM10 24-Hour Standard, between 2000 and 2010.

Reported, are the total exceedances for each station and the average of each 3-year period (i.e., the design value). Compliance 

with the NAAQ is met when the average number of exceedances in the 3-year period is less or equal to 1. Numbers in red 

indicate exceedance conditions. 

Elko 

Grammar 

School #2

Linda Street Church

Manse 

Elementary 

School

Glenoaks 

Street

2004-2006 --- 0 0 --- ---

2005-2007 --- 0 0 0 ---

2006-2008 --- 0 0 0 ---

2007-2009 0 0 0 0 ---

2008-2010 0 0 0 0 0

Battle 

Mountain 

High School

State Offices 

Building

Community

Pool Willow Creek

1998-2000 1 (0.3) 0 --- ---

1999-2001 1 (0.3) 0 4 (1.3) ---

2000-2002 1 (0.3) 1 (0.3) 18 (6.0) ---

2001-2003 --- 1 (0.3) 21 (7.0) ---

2002-2004 --- 1 (0.3) 14 (4.7) ---

2003-2005 --- 0 19 (6.3) ---

2004-2006 --- 0 2 (0.7) 2 (0.7)

2005-2007 --- 0 --- 1 (0.3)

2006-2008 --- 0 --- 1 (0.3)
Nevada Air Quality Trend Report, 2000-2010

27

Figure 18: Annual average for PM10 from active (above) and discontinued (below) monitors

0

10

20

30

40

50

60

2000 2002 2004 2006 2008 2010

Concentration (

μg m-3

)

Elko Grammar School #2 Linda Street Church

Manse Elementary School Glenoaks Street

0

10

20

30

40

50

60

2000 2002 2004 2006 2008 2010

Concentration (μg m-3

)

Battle Mountain High School State Offices Building Community Pool

Willow Creek Cave Rock State Park
Nevada Air Quality Trend Report, 2000-2010

28

2.7 Sulfur Dioxide

Sulfur oxides (SO2) commonly originate from burning fossil fuels and are also produced from various 

industrial processes. SO2 is the measured criteria pollutant of concern. In the air, SO2 reacts with oxygen, 

ammonia and other compounds, including water vapor, to form sulfate salts and sulfuric acid mist. 

Sources of SO2 include metal smelters, oil refineries, and large oil- or coal-fired power plants. Across the 

United States, the largest sources of SO2 emissions are from fossil fuel combustion at power plants 

(66%) and other industrial facilities (29%). Smaller sources of SO2 emissions include industrial processes 

such as extracting metal from ore as well as the burning of high sulfur containing fuels by locomotives, 

large ships, and nonroad equipment. Since 2010, USEPA recognizes a 1-hour primary standard for SO2 at 

a level of 75 ppb, and a 3-hour average secondary standard. To attain the primary standard, the 3-year 

average of the 99th percentile of daily maximum distribution (based on 1-hour averages) must not 

exceed 75 ppb. To attain the secondary standard, the 3-hour average concentration cannot exceed 0.5 

ppm more than once per year. 

NAPCP MONITORING NETWORK:

During the reporting period, NAPCP did not conduct ambient monitoring for SO2 because monitoring 

threshols established by USEP have not been met in any of Nevada’s 15 Rural Counties. However, the US 

Forest Service monitors SO2 at the Jarbidge Wilderness area through the IMPROVE network 

(http://vista.cira.colostate.edu/improve/Overview/Overview.htm). 

ATTAINMENT STATUS:

With the exception of the central Steptoe Valley (near Ely), USEPA has designated all areas in Nevada’s 

15 Rural Counties as unclassifiable. Prior to 2002, the central Steptoe Valley was designated by USEPA 

as SO2 non-attainment due to the historic operation of a copper smelter at McGill. The smelter ceased 

operation in 1983 and NAPCP requested reclassification of the area to attainment. USEPA approved the 

request on April 12, 2002. USEPA will designate areas for the 2010 standard in 2013 

(http://www.epa.gov/so2designations/). NAPCP expects its jurisdiction to remain unclassifiable.
Nevada Air Quality Trend Report, 2000-2010

29

2.7.1 National Sulfur Dioxide Trend

Nationally, average SO2 concentrations have decreased over the years. From 1980 to 2010 there was an 

81% decrease in the national SO2 average. From 2000 to 2010 there was a 52% decrease in the national 

SO2 average. The reduction in average SO2 concentrations is mainly the result of switching to low sulfur 

fossil fuels especially in on-road and off-road vehicles (http://www.epa.gov/airtrends/sulfur.html).

Figure 19: Annual national average for SO2 from 1980 to 2010 (black dashed line), based on 121 (1980-

1989), 229 (1990-1999), and 341 site (2000-2010). Blue area delimits the 10th and 90th percentile of the annual 

distribution of concentrations reported by all sites nationwide (http://www.epa.gov/airtrends/sulfur.html). 

0

5

10

15

20

25

30

Concentration (ppb)

Annual Average
Nevada Air Quality Trend Report, 2000-2010

30

3 Appendixes

3.1 Monitoring Station Description

Monitoring stations active at any time during the 2000-2010 period are described in this section. A 

synopsis of all stations and data availability is presented at in section 3.2.

High School, Battle Mountain

32-015-0004 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1998-2002

Project Type = Population Oriented Surveillance

Measurement Scale = Neighborhood

Located at 625 Weaver Avenue in Battle Mountain, this PM10 site was on the grounds of Battle 

Mountain High School. This site was at the edge of a residential neighborhood, near the intersection of 

Interstate Highway 80 and Nevada Highway 305. The TEOM continuous PM10 monitor was sited on the 

announcer's tower at the school’s athletic field. Monitoring commenced on August 20, 1998 and was 

discontinued in 2002.
Nevada Air Quality Trend Report, 2000-2010

31

Fifth Street, Carson City

32-510-0002 (SLAMS/SSMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1981-1989 1974-1989,

2008-2010 2009-2010 1991-1997

Project Type = Population Oriented Surveillance (Typical Concentration)

Measurement Scale = Neighborhood

Located at 3300 East Fifth Street in Carson City, this CO, O3, and PM2.5 site is near the Carson City Public 

Works Department maintenance yard. In addition, meteorological data is collected at the Fifth Street 

site. This site is situated in a transition area that is adjacent to the maintenance yard, a sewage 

treatment plant, residential neighborhoods, wetlands, and the new extension of Highway 580. CO and 

O3 were monitored from 1974 through 1989. PM10 monitoring commenced in March 1991 and was 

discontinued at the end of February 1997. In 2006, an existing meteorological station was restarted. In 

2008, O3 monitoring commenced at the Fifth Street site. In 2009, PM2.5 monitoring commenced at the 

Fifth Street site11. This station was discontinued and relocated in December 2012.

 

11 The O3 and PM2.5 monitors were relocated from the Long Street site.
Nevada Air Quality Trend Report, 2000-2010

32

Long Street, Carson City

32-510-0004 (SLAMS/SSMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1997-2008 1997-1998 1997-2007 1998-2009 1997-1998

Project Type = Highest Concentration and Population Oriented Surveillance (Typical Concentrations)

Measurement Scale = Neighborhood (Urban) (Middle)

Located at 875 East Long Street in Carson City, this CO, O3, NO2, PM2.5, and PM10 site was in the Sierra 

Pacific Power Company yard. This site monitored highest concentrations and population exposure 

downwind of the main traffic corridors and the commercial part of the city. This site began monitoring 

for CO, O3, NO2, and PM10 in 1997. PM2.5 monitoring commenced in January 1998. NO2 monitoring was 

discontinued in October 1997 and PM10 sampling was discontinued at the end of June 1998. The Long 

Street O3 monitor was relocated to the Fifth Street site after the 2007 O3 season.12 In 2008, NAPCP

requested USEPA for discontinuation of CO monitoring based upon no violations of the NAAQS from 

2002 to 2007. USEPA allowed CO monitoring to be discontinued at the end of 2008. In the summer of 

2009, the Long Street site was discontinued and the special study PM2.5 monitor was relocated to the 

Fifth Street. 

 

12 The Long Street O3 monitor was relocated due to concern that trees adjacent to the site may have been 

interfering with the O3 sampling.
Nevada Air Quality Trend Report, 2000-2010

33

State Offices Building, Elko

32-007-0004 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1992-2008

Project Type = Population Oriented Surveillance

Measurement Scale = Urban

Located at 850 Elm Street in Elko, this continuous PM10 site was on the roof of the state offices building. 

This site was situated in a predominantly residential area. PM10 sampling commenced at this site in 

November 1992. This monitor was previously located at the Fire Station at 723 Railroad Street (ID #32-

007-0003) in a commercial area. It was moved to the State Offices Building at 850 Elm Street in 

November 1992. At the end of 1998, the manual PM10 sampler was replaced with a TEOM continuous 

PM10 monitor. In September 2008, the TEOM monitor was closed and a new beta attenuation monitor 

was sited at the Elko Grammar School #2.
Nevada Air Quality Trend Report, 2000-2010

34

Elko Grammar School #2, Elko

32-007-0005 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2008-2010

Project Type = Population Oriented Surveillance (Typical Concentration)

Measurement Scale = Neighborhood

Located at 1055 7th Street in Elko, this PM10 site is on the grounds of Elko Grammar School #2. This site is 

situated in a residential neighborhood. PM10 monitoring commenced at this site in September 2008 

when the beta attenuation monitor was installed.
Nevada Air Quality Trend Report, 2000-2010

35

West End Elementary School, Fallon

32-001-0002 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1999-2010 1993-1998

Project Type = Population Oriented Surveillance

Measurement Scale = Urban

Located at 280 South Russell Street in Fallon, this O3 and PM10 site is on the grounds of the West End 

Elementary School. This site is situated in a residential neighborhood that may at times be affected by 

agricultural operations surrounding the town. PM10 sampling (SLAMS) commenced at this site in May 

1993 and was discontinued at the end of June 1998. Monitoring for O3 began in October 1999 as an O3

transport site downwind of Reno and Fernley. In 2008, the O3 monitor was reclassified as a SLAMS. 
Nevada Air Quality Trend Report, 2000-2010

36

Fire Station, Fernley

(SPMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1998-2003

Project Type = Highest Concentration and Population Oriented Surveillance 

Measurement Scale = Urban

Located at 195 East Main Street in Fernley, this O3 site was at the North Lyon County Fire Protection 

District Station. This site was generally downwind from Reno at the end of a canyon corridor that 

includes large industrial sources. O3 monitoring commenced in September 1997 and was discontinued at 

the end of September 2003. 
Nevada Air Quality Trend Report, 2000-2010

37

Intermediate School, Fernley

32-019-0006 (SLAMS/SSMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2004,

2007-2010 1999-2010 1995-1998

Project Type = Population Oriented Surveillance

Measurement Scale = Urban

Located at 320 Hardie Lane in Fernley, this O3, PM2.5, and PM10 site is on the grounds of Fernley 

Intermediate School. This site is situated in a residential and agricultural area that has experienced 

recent industrial growth. Sampling for PM10 commenced at this site in May 1995 to determine 

agricultural and industrial source impacts and population exposure. PM10 sampling was discontinued in 

November 1998. PM2.5 special study monitoring (SSMS) commenced in June 1999. O3 monitoring 

(SLAMS) occurred during 2004 and resumed in July 2007.
Nevada Air Quality Trend Report, 2000-2010

38

Gardnerville Ranchos, Gardnerville

32-005-0007 (SLAMS/SSMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1998-2010 1995-1998

Project Type = Population Oriented Surveillance (Typical Concentration)

Measurement Scale = Neighborhood

Located at 820 Lyell Way in Gardnerville, this PM2.5 and PM10 site is in Aspen Park in the Gardnerville 

Ranchos. This site is situated in a residential neighborhood. PM10 monitoring (SLAMS) commenced at 

this site in December 1995 and was discontinued at the end of June 1998. Special study monitoring for 

PM2.5 (SSMS) commenced in January 1998.
Nevada Air Quality Trend Report, 2000-2010

39

IMPROVE Site, Great Basin National Park

32-033-0101 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1998-2010

Project Type = Background

Measurement Scale = Regional

The IMPROVE (Interagency Monitoring of Protected Visual Environments) program implement an 

extensive long term monitoring program to establish the current visibility conditions, track changes in 

visibility and determine causal mechanisms for the visibility impairment in the National Parks and 

Wilderness Areas (http://vista.cira.colostate.edu/improve/). This monitoring station is located at the 

Lehman Caves in the Great Basin National Park near Baker. The National Park Service started O3

sampling in 1998.
Nevada Air Quality Trend Report, 2000-2010

40

Community Pool, Pahrump

(32-023-0010 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2001-2004

Project Type = Highest Concentration

Measurement Scale = Neighborhood

Located at 250 North Highway 160 in Pahrump, this PM10 site was on the grounds of the municipal 

swimming pool and recreation complex. The continuous beta attenuated monitor was sited on the roof 

of a dressing room. This site was situated in a commercial neighborhood behind the County offices. PM10

monitoring commenced in January 2001 and ended in November 2004. The site was closed due to 

reconstruction of the pool-building from a flat to a pitched roof. 
Nevada Air Quality Trend Report, 2000-2010

41

Linda Street, Pahrump

(32-023-0011 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2003-2010

Project Type = Background

Measurement Scale = Regional

Located at 8825 North Linda Street in Pahrump, this PM10 site is on the premises of a private residence. 

The continuous beta attenuated monitor is sited on the roof of an old railroad box car. This location is 

the most rural and northern-most site in the Pahrump Valley monitoring network. There are some 

residential plats surrounding this site, but the area mainly consists of native desert vegetation with little 

or no land surface disturbances. There are gravel roads in the area, but they experience little traffic. 

PM10 monitoring commenced in May 2003. 
Nevada Air Quality Trend Report, 2000-2010

42

Willow Creek, Pahrump

(32-023-0012 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2004-2009

Project Type = Highest Concentration and Population Oriented Surveillance (Typical Concentration)

Measurement Scale = Urban

Located at 1500 Red Butte in Pahrump, this PM10 site was on the Willow Creek Golf Course. The 

continuous beta attenuated monitor was sited on the roof of a pump house for the golf course between 

fairways. PM10 monitoring commenced in December 2003. The Willow Creek Golf Course is surrounded 

by residential plats and vacant land. While the Community Pool site was in operation, the purpose of the 

Willow Creek site was to determine population exposure in central Pahrump. After the Community Pool 

site was closed in November 2004, the purpose of the Willow Creek site became monitoring the highest 

concentrations. In July 2009, the Willow Creek site was relocated to a new site on the golf course, 410 

South Glenoaks Street, approximately one-third of a mile southwest of the original site.
Nevada Air Quality Trend Report, 2000-2010

43

Church, Pahrump

(32-023-0013 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2004-2010

Project Type = Source Impact

Measurement Scale = Neighborhood

Located at 781 East Gamebird in Pahrump, this PM10 site is on the grounds of Our Lady of the Valley 

Catholic Church. The continuous beta attenuated monitor is sited in the southeast corner of the Catholic 

Church lot. This site is situated in a residential area with some commercial plats and native desert. There 

is a mix of paved and dirt roads in the vicinity. The Church Site began operation in 2004 to complement 

the existing three other sites in the Pahrump Valley monitoring network. This PM10 site is the southernmost monitoring site in the Pahrump Valley. 
Nevada Air Quality Trend Report, 2000-2010

44

Manse Elementary School, Pahrump

(32-023-0014 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2005-2010

Project Type = Highest Concentration

Measurement Scale = Middle

Located at 1020 East Wilson Road in Pahrump, this PM10 site is on the grounds of the Manse Elementary 

School. This site replaced the Community Pool site. The continuous beta attenuated monitor is sited on 

the roof of the school. This site is situated adjacent to the busiest activity area of Pahrump in a mostly 

commercial area, with some residential plats. This PM10 site is located downwind from land surface 

disturbances such as residential construction developments that have cleared large swaths of ground 

and agricultural lands. There is a mix of paved and dirt roads in the vicinity.
Nevada Air Quality Trend Report, 2000-2010

45

Glenoaks Street, Pahrump

(32-023-0015 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

2009-2010

Project Type = Population Oriented Surveillance (Typical Concentration)

Measurement Scale = Neighborhood

Located at 410 South Glenoaks Street in Pahrump, this PM10 monitor is on the Willow Creek Golf Course. 

In July 2009, this site replaced the original Willow Creek site which was located approximately one-third 

of a mile to the northeast. The continuous beta attenuated monitor is sited on the grounds of the 

wastewater treatment plant. PM10 monitoring commenced in October 2009.
Nevada Air Quality Trend Report, 2000-2010

46

Harvey’s Resort Hotel, Stateline

(32-005-0009 SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1999-2010

Monitoring Objective = Highest Concentration

Measurement Scale = Micro

Located at 18 Highway 50 in Stateline, this CO site is on the 1st level of Harvey’s Resort and Hotel’s 

parking garage facing the highway. This is a "micro-scale" monitoring site for CO in the core of the 

Stateline casino hotel area at Lake Tahoe. The site is designed to monitor the highest CO concentrations 

at Lake Tahoe, and is taken to be representative of both the California and Nevada sides of the south 

shore casino district. CO monitoring at this site commenced in October 1999 and was previously is 

conducted by the California Air Resources Board by multi-agency cooperative agreement. Starting in July 

2006, NDEP took over the monitoring responsibility for this site under a maintenance agreement with 

EPA. In June 30th 2012, this monitoring station was discontinued, after 33 years of data below the 

NAAQS. 
Nevada Air Quality Trend Report, 2000-2010

47

Cave Rock State Park, Zephyr Cove

32-005-0008 (SLAMS)

Pollutant(s) Monitored

CO NO2 O3 PM2.5 PM10

1999-2004 2000-2001 2000-2001

Project Type = Regional Transport

Measurement Scale = Regional

Located at Cave Rock State Park in Zephyr Cove, this O3, PM2.5, and PM10 site was on the boat launch 

facility. This site monitored O3 transport from upwind California urban areas. O3 monitoring commenced

in July 1999 and was discontinued at the end of February 2004. PM2.5 and PM10 monitoring commenced 

at the end of 1999. PM2.5 monitoring was discontinued on January 15, 2002. PM10 monitoring was 

discontinued on January 22, 2002. 
Nevada Air Quality Trend Report, 2000-2010

48

3.2 Monitoring Data Availability

The following table lists years during which air quality monitors were operated for the pollutant 

indicated. A blank space indicates that the specific pollutant has not been monitored for at that site.

Station Name Location Site # O3 NO2 CO PM10 PM2.5

Battle Mountain

Police & Fire Station 25 E. Second St. 32-015-0002 85-98

High School 625 Weaver Ave. 32-015-0004 98-02

Carson City

Fifth Street13 3300 E. Fifth St. 32-510-0002 74-98,08-12 81-89 91-97 09-12

Bordewich School 110 Thompson Dr. 32-510-0003 94-98

Long Street 875 E. Long St. 32-510-0004 97-07 97-98 97-08 97-98 98-09

Ann Street E Ann St. SPMS 90-93

Roberts House Hwy 395 & Corbett St. SPMS 89,94-96

Elko

State Offices Building 850 Elm St. 32-007-0004 92-08

Grammar School No. 2 1055 Seventh St. 32-007-0005 08-12

Fallon

West End School 280 S. Russell St. 32-001-0002 99-12 93-98

Fernley

Intermediate School 320 Hardie Lane 32-019-0006 07-12 95-98 99-12

Fire Station 163 E. Main St. SPMS 98-03

Gardnerville

Mitch Drive 931 Mitch Dr. 32-005-0006 94-96

Gardnerville Ranchos 820 Lyell Way 32-005-0007 95-98 98-12

Great Basin National Park

Lehman Caves Maintenance Bldg. 32-033-0007 93-95

Lehman Caves IMPROVE site 32-033-0008 95-97

Lehman Caves IMPROVE site 32-033-0101 93-12

Lovelock

Post Office Main St. & Dartmouth Ave. 32-027-0002 91-97

High School 1215 Franklin Ave. 32-027-0003 *

McGill

Elementary School 25 F Ave. 32-033-0002 93-98

Minden

Dispatch Center 1615 Eight St. 32-005-0005 93-98

Law Enforcement 

Bldg. 1625 Eight St. SPMS 98-99

Pahrump

Community Pool 250 N. Hwy 160 32-023-0010 01-04

Linda Street 8825 N. Linda St. 32-023-0011 03-12

Willow Creek 1500 Red Butte 32-023-0012 04-09

Church 781 E. Gamebird Rd. 32-023-0013 04-12

Manse School 1020 E. Wilson Rd. 32-023-0014 05-12

Glenoaks Street 41- S. Glenoaks St. 32-023-0015 09-12

Stateline

Horizon Casino Resort 50 Hwy 50 32-005-0004 81-99 90-97 82-99 88-9

Harvey’s Resort 

Hotel14 18 Hwy 50 32-005-0009 99-12

Zephyr Cove

Cave Rock State Park Boat Ramp 32-005-0008 99-04 00-01 00-01

*Data collected was deemed invalid by USEPA

 

13 This station was discontinued and relocated to a different location in December 2012.

14 This station was discontinued in June 2012.
Nevada Air Quality Trend Report, 2000-2010

49

3.3 Monitoring Data

Monitoring Methods Used in Nevada, 2000-2010

Pollutant Method Units

CO Gas Nondispersive Infrared Radiation ppm

O3 UV Absorption ppm

PM2.5 Met-One BAM 1020 μg/m3

PM2.5 Met-One ES-640 μg/m3

PM10 Reference - Hi Vol Andersen/GMW 1200 μg/m3

PM10 R&P TEOM Mass Transducer μg/m3
Nevada Air Quality Trend Report, 2000-2010

50

Carbon Monoxide

There was one active CO monitor under NDEP’s jurisdiction, Harvey’s Resort Hotel in Stateline 

(discontinued in 2012). Between 2000 and 2010 CO data was also collected at the monitor station on 

Long Street in Carson City from 1997 to 2008.
Nevada Air Quality Trend Report, 2000-2010

51

Compliance with the current CO NAAQS is met when:

 The 8-hour average does not exceed 9 ppm more than once per year

 The 1-hour average does not exceed 35 ppm more than once per year

Table 3: Carbon monoxide. Annual maxima (ppm) and number of exceedances (in parenthesis) for each NAAQS for the 

Long Street and Harvey’s Resort Hotel in the 2000-2010 period.

Long Street Harvey’s Resort Hotel

8-hour 1-hour 8-hour 1-hour

2000 3.8 (0) 8.0 (0) 4.4 (0) 13.0 (0)

2001 3.9 (0) 7.0 (0) 3.7 (0) 7.6 (0)

2002 3.9 (0) 8.3 (0) 8.8 (0) 17.2 (0)

2003 3.3 (0) 5.5 (0) 7.3 (0) 13.0 (0)

2004 3.3 (0) 6.0 (0) 4.4 (0) 12.0 (0)

2005 2.9 (0) 4.3 (0) 3.8 (0) 12.7 (0)

2006 2.8 (0) 4.8 (0) 3.1 (0) 5.2 (0)

2007 2.8 (0) 4.8 (0) 4.5 (0) 7.8 (0)

2008 2.2 (0) 2.9 (0) 2.6 (0) 5.8 (0)

2009 3.4 (0) 10.5 (0)

2010 3.2 (0) 5.8 (0)
Nevada Air Quality Trend Report, 2000-2010

52

Ground-Level Ozone Monitoring Data

There were three active O3 monitors under NDEP’s jurisdiction, Fifth Street in Carson City (discontinued 

and relocated in December 2012), West End Elementary School in Fallon, and Intermediate School in 

Fernley. In addition, O3 data is collected by the National Park Service at the IMPROVE Site in Great Basin 

National Park. Between 2000 and 2010, O3 data was also collected at four other monitors, Long Street in 

Carson City, Fire Station in Fernley, Horizon Casino Resort in Stateline, and Cave Rock State Park in 

Zephyr Cove. 
Nevada Air Quality Trend Report, 2000-2010

53

Compliance with the current O3 NAAQS is met when the 3-year average of the annual 4th-highest daily 

maximum value, based on the 8-hour average, does not exceed 0.1 ppm.

Table 4: Ozone: 3- year average of the annual 4th- highest daily maximum value, based on the 8-hour average, for all the 

stations measuring O3 between 2000 and 2010.

Fifth 

St.

West End Elem. 

Sch.

Fernley Int. 

Sch.

Great Basin 

NP

Long 

St.

Fernley Fire 

St.

Cave Rock 

SP

2000-2002 0.073 0.07 0.067 0.073

2001-2003 0.071 0.069 0.066 0.071

2002-2004 0.072 0.067 0.064

2003-2005 0.072 0.064

2004-2006 0.072 0.066

2005-2007 0.064 0.073 0.066

2006-2008 0.068 0.073

2007-2009 0.066 0.063 0.072

2008-2010 0.069 0.063 0.063 0.070

2009-2011 0.066 0.059 0.064 0.070
Nevada Air Quality Trend Report, 2000-2010

54

PM2.5 Monitoring Data

There were three active PM2.5 monitors under NDEP’s jurisdiction, Fifth Street in Carson City 

(discontinued and relocated in December 2012), Intermediate School in Fernley, and Gardnerville 

Ranchos in Gardnerville. Between 2000 and 2010, PM2.5 data was also collected at two other monitors, 

Long Street in Carson City and Cave Rock State Park in Zephyr Cove. 
Nevada Air Quality Trend Report, 2000-2010

55

Compliance with the current PM2.5 NAAQS is met when 

 The 3-year average of the annual mean does not exceed 15 μg/m3

 The 3-year average of the 98th percentile value of the 24-hour average, does not exceed 35 

μg/m3

Table 5: PM10: 3-year average for annual mean and annual 98th percentile of 24-hour average. Fifth Street and Cave Rock 

NP stations are not shown as they did not have 3 consecutive years of data. The threshold for the 24-hour NAAQS was changed 

from 65 μg/m3to 35 μg/m3in 2007, therefore all stations were in compliance during the 2000-2010 period.

Long St. Fifth St. Fernley Inter. Sch. Gardnerville Ranchos

Annual 

mean

98th perctl. Annual 

mean

98th perctl. Annual 

mean

98th perctl. Annual 

mean

98th perctl.

2000-2002 4.78 23.90 5.03 21.70 6.17 29.43

2001-2003 4.39 20.53 4.47 18.53 6.08 28.33

2002-2004 4.11 20.97 3.91 15.00 6.45 30.47

2003-2005 4.81 36.23*

3.85 14.10 7.00 45.20*

2004-2006 4.78 36.43*

13.80 8.91 46.10*

2005-2007 5.39 34.90 12.83 10.19 42.20*

2006-2008 21.30 10.60 11.37 26.97

2007-2009 24.83 4.20 14.47 11.15 28.43

2008-2010 4.43 15.43 11.73 29.17

2009-2011 13.40 27.00 4.78 15.20 10.89 29.30

* NAAQS threshold was 35 μg/m3
Nevada Air Quality Trend Report, 2000-2010

56

PM10 Monitoring Data

There are five active PM10 monitors under NDEP’s jurisdiction, Grammar School #2 in Elko as well as 

Linda Street, Church, Manse Elementary School, and Glenoaks Street in Pahrump. Between 2000 and 

2010, PM10 data was also collected at 5 other monitoring sites, Battle Mountain High School in Battle 

Mountain, State Offices Building in Elko, Community Pool in Pahrump, Willow Creek in Pahrump, and 

Cave Rock State Park in Zephyr Cove. 
Nevada Air Quality Trend Report, 2000-2010

57

Compliance with the current PM10 is met when the 24-hour average does not exceed 150 μg/m3 more 

than once per year, on a 3-year average basis. 

Table 6: Total number of exceedances of the PM10 24-Hour Standard, between 2000 and 2010.

Reported, are the total exceedances for each station and the average of each 3-year period (i.e., the design value). Compliance 

with the NAAQ is met when the average number of exceedances in the 3-year period is less or equal to 1. Numbers in red 

indicate exceedance conditions.

Elko Grammar 

School #2 Linda Street Church

Manse 

Elementary 

School

Glenoaks 

Street

2004-2006 --- 0 0 --- ---

2005-2007 --- 0 0 0 ---

2006-2008 --- 0 0 0 ---

2007-2009 0 0 0 0 ---

2008-2010 0 0 0 0 0

Battle 

Mountain High 

School

State Offices 

Building

Community

Pool Willow Creek

1998-2000 1 (0.3) 0 --- ---

1999-2001 1 (0.3) 0 4 (1.3) ---

2000-2002 1 (0.3) 1 (0.3) 18 (6.0) ---

2001-2003 --- 1 (0.3) 21 (7.0) ---

2002-2004 --- 1 (0.3) 14 (4.7) ---

2003-2005 --- 0 19 (6.3) ---

2004-2006 --- 0 2 (0.7) 2 (0.7)

2005-2007 --- 0 --- 1 (0.3)

2006-2008 --- 0 --- 1 (0.3)