Ventura County Air Pollution Control District 

2011 Ambient Air Monitoring Network Plan 

July, 2011 

Prepared By The Monitoring Division 

Kent Field, Manager 

Ventura County Air Pollution Control District 

669 County Square Drive 

Ventura, CA 93003 

(805) 645-1400 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD I MONITORING DIVISION 

Table of Contents 

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

2 Overview of Network Operation................................................................2

2.1 Physical Setting And Regional Description ..............................................2

2.2 VCAPCD Monitoring Stations...................................................................4

2.3 Monitoring Objectives And Spatial Scales................................................7

2.4 Minimum Monitoring Requirements..........................................................9

2.4.1 Ozone........................................................................................................9

2.4.2 PM2.5 .......................................................................................................11

2.4.3 PM10 ........................................................................................................12

2.4.4 PAMS......................................................................................................13

2.4.5 Carbon Monoxide....................................................................................13

2.4.6 Nitrogen Dioxide .....................................................................................14

2.4.7 Sulfur Dioxide..........................................................................................14

2.5 Local Monitoring Objectives And Local Spatial Scales ..........................14

3 Recent Or Pending Modifications To The Air Monitoring Network.........16

3.1 Discontinued Monitoring Station – Ventura–Emma Wood State 

Beach ................................................................................................................17 

3.2 Pending Changes To The PM2.5 Monitoring Network.............................17

3.3 Pending Changes To The PM10 Monitoring Network .............................18

3.4 Pending Changes To The PAMS Network.............................................19

3.5 Pending Changes To The NO2 Network.................................................20

3.6 Status Of SO2..........................................................................................20

3.7 Status Of Lead........................................................................................21

3.8 Proposed Changes To The Speciation Trends Network (STN).............21

3.9 Pending Changes To The Data Acquisition And Management 

System ................................................................................................................21

4 Required Quality Assurance Of The Monitoring Program......................22

5 Data Submission Requirements.............................................................24

5.1 Air Quality Data.......................................................................................24

Appendix A Detailed Station Information 

Detailed Station Information El Rio – Rio Mesa School #2.....................................A-1

Detailed Station Information Ojai – Ojai Avenue.....................................................A-7

Detailed Station Information Piru – Pacific Avenue...............................................A-11

Detailed Station Information Simi Valley – Cochran Street...................................A-16

Detailed Station Information Thousand Oaks – Moorpark Road ..........................A-23

Detailed Station Information Ventura - Emma Wood State Beach .......................A-28

Detailed Station Information Simi Valley – Upper Air............................................A-32
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD II MONITORING DIVISION 

List of Tables 

Table 1 -Air Monitoring Stations, Regions Served And Pollutants Monitored 

 in 2010 ..................................................................................................................6

Table 2 - Monitoring Objectives And Appropriate Spatial Scales................................8

Table 3 – Pollutants, Monitoring Objectives And Spatial Scales.................................8

Table 4 – Ozone: Number of Days > Than The Level Of The 8-Hour NAAQS and 

National Design Values .............................................................................................10

Table 5 – Ozone: Minimum Monitoring Requirements.............................................11

Table 6 - PM2.5: Annual 98th Percentile 24-Hour Averages And 24-Hour National 

Design Values............................................................................................................11

Table 7 - PM2.5: Annual Weighted Means And Annual National Design Values......11

Table 8 - PM2.5: Minimum Monitoring Requirements................................................12

Table 9 – PM10: Annual Maximum 24-Hour Averages And 3-Year Average Of 

Annual Estimated Exceedances................................................................................12

Table 10 - PM10: Minimum Monitoring Requirements ..............................................13

Table 11 - Local Air Monitoring Regions - Area and Population Served..................15

Table 12 – CY-2012 PM2.5 Comparison Study..........................................................18

Table 13 – CY-2013 Pending Final PM2.5 Network ...................................................18

Table 14 – CY-2012 PM10 Comparison Study ..........................................................19

Table 15 – CY-2013 Pending Final PM10 Network....................................................19

Table 16 - Sources Of Ambient Air Quality Data.......................................................24

Appendix A Detailed Station Information 

Table 17 – El Rio PM2.5 Annual Maximum Averages..............................................A-2

Table 18 – El Rio PM10 Annual Maximum 24-Hour Averages ................................A-3

Table 19 – El Rio Station Information......................................................................A-3

Table 20 – El Rio Monitor Information.....................................................................A-4

Table 21 – Ojai PM10 Maximum 24-Hour Averages................................................A-8

Table 22 – Ojai Station Information.........................................................................A-9

Table 23 – Ojai Monitor Information ........................................................................A-9

Table 24 – Piru – Pacific Avenue PM2.5 Maximum Averages ...............................A-12

Table 25 – Piru Station Information.......................................................................A-13

Table 26 – Piru Monitor Information ......................................................................A-13

Table 27 – Simi Valley PM2.5 Maximum Averages................................................A-17

Table 28 – Simi Valley PM10 Annual Maximum 24-Hour Averages......................A-18

Table 29 – Simi Valley Station Information............................................................A-18

Table 30 – Simi Valley Monitor Information...........................................................A-19

Table 31 – Thousand Oaks PM2.5 Maximum Averages........................................A-24

Table 32 – Thousand Oaks Station Information....................................................A-25
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VENTURA COUNTY APCD III MONITORING DIVISION 

List of Tables - Continued 

Table 33 – Thousand Oaks Monitor Information...................................................A-25

Table 34 – Ventura Station Information.................................................................A-29

Table 35 – Ventura Monitor Information................................................................A-30

Table 36 – Simi Valley – Upper Air Station Information ........................................A-32
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VENTURA COUNTY APCD IV MONITORING DIVISION 

List of Figures 

Figure 1 – VCAPCD Monitoring Regions And Ambient Monitoring Stations ..............5

Figure 2- Historic Ozone Trends: National Design Value (3 Year Average Of 4th

Highest Annual Maximum 8-Hour Average)..............................................................10

Appendix A Detailed Station Information 

Figure 3 - Ozone Trends Summary: El Rio-Rio Mesa School #2 ...........................A-2

Figure 4 – Map Showing Location Of El Rio – Rio Mesa School #2.......................A-6

Figure 5 - Ozone Trends Summary: Ojai - Ojai Avenue .........................................A-8

Figure 6 – Map Showing Location Of Ojai – Ojai Avenue.....................................A-10

Figure 7 - Ozone Trends Summary: Piru – Pacific Avenue .................................A-12

Figure 8 – Map Showing Location Of Piru – Pacific Avenue.................................A-15

Figure 9 - Ozone Trends Summary: Simi Valley-Cochran Street .........................A-17

Figure 10 – Map Showing Location Of Simi Valley – Cochran Street...................A-22

Figure 11 - Ozone Trends Summary: Thousand Oaks-Moorpark Road...............A-24

Figure 12 – Map Showing Location Of Thousand Oaks – Moorpark Road..........A-27

Figure 13 - Ozone Trends Summary: Ventura-Emma Wood State Beach...........A-29

Figure 14 – Map Showing Location of Ventura – Emma Wood State Beach.......A-31

Figure 15 – Map Showing Location Of Simi Valley – Upper Air............................A-32
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD V MONITORING DIVISION 

Definition of Terms 

AQS Air Quality System 

ARM Approved Regional Method 

BAM Beta Attenuation Monitor 

CARB California Air Resources Board 

CFR Code of Federal Regulations 

CMSA Consolidated Metropolitan Statistical Area 

CO Carbon Monoxide 

DV Design Value 

EPA U. S. Environmental Protection Agency 

FEM Federal Equivalent Method 

FRM Federal Reference Method 

NAAQS National Ambient Air Quality Standards 

NMHC Non-Methane Hydrocarbons 

NO2 Nitrogen Dioxide 

O3 Ozone 

PAMS Photochemical Assessment Monitoring Systems 

PM Particulate Matter 

PM2.5 Particulates less than or equal to 2.5 microns in size 

PM10 Particulates less than or equal to 10 microns in size 

SIP State Implementation Plan 

SLAMS: State and Local Air Monitoring Stations 

SO2 Sulfur Dioxide 

VCAPCD Ventura County Air Pollution Control District 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 1 MONITORING DIVISION 

1 Introduction 

The Ventura County Air Pollution Control District’s (VCAPCD) 2010 Ambient Air 

Monitoring Network Plan is an examination and evaluation of the VCAPCD’s network 

of ambient air pollution monitoring stations. This annual review of the VCAPCD’s 

SLAMS (State and Local Air Monitoring Station) air monitoring network is required by 

Title 40, Code of Federal Regulations, Part 58.10 (40 CFR 58.10). The report meets 

requirements for an annual network plan as listed in 40 CFR 58.10 Appendix A. 

As required by the regulations, this report includes monitors which are federal 

reference methods (FRM) or federal equivalent methods (FEM). While the CFR also 

requires reporting of approved regional methods (ARM), no ARMs are in operation 

within VCAPCD at this time. The terms FRM, FEM, and ARM denote monitoring 

instruments that produce measurements of the ambient pollution levels that the 

regulations allow to be compared to the NAAQS’s for regulatory purposes. 

Federal Regulations require specific detailed monitoring network information be 

included. It includes a review of actions taken during 2010 and plans for action in the 

year ahead. The regulations require that the report be submitted to EPA in July of 

each year. 

This report will be available for a 30 day public inspection period, with comments to 

be submitted to the EPA. This report may be viewed on the VCAPCD’s web site, 

www.vcapcd.org and hardcopies are available for review at VCAPCD’s office. For 

2011, comments will be received and forwarded to EPA through August 15, 2011. 

Written comments should be submitted to Kent Field, Monitoring Division Manager 

at, kent@vcapcd.org, (805) 662-6960 and CC: to Herm Ragsdale at 

herm@vcapcd.org (808) 662-6954. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 2 MONITORING DIVISION 

2 Overview of Network Operation 

The VCAPCD operates six air monitoring stations and one upper air profiler within 

Ventura County. The VCAPCD’s SLAMS monitoring network has been designed to 

provide ozone, PM2.5 and PM10 monitoring coverage to the majority of the inhabited 

regions of Ventura County. The VCAPCD has conducted air monitoring for ozone or 

oxidants in Ventura County since 1963. This monitoring network plays a critical role 

in assessing Ventura County’s clean air progress and in determining pollutant 

exposures throughout Ventura County. 

2.1 Physical Setting And Regional Description 

Ventura County is located along the southern portion of the central California coast 

between Santa Barbara and Los Angeles Counties. Its diverse topography is 

characterized by mountain ranges to the north, two major river valleys (the Santa 

Clara, which trends east-west, and the Ventura, which trends roughly north-south), 

and the Oxnard Plain to the south and west. As pollutants are carried into the inland 

valleys by prevailing winds, they are frequently trapped against the mountain slopes 

by a temperature inversion layer, generally occurring between 1500 and 2500 feet 

above sea level. Above the temperature inversion layer, pollutants are allowed to 

disperse freely. Our air monitoring stations are therefore found between the coast 

and the inland valley mountain foothills up to approximately 1000 feet. 

Ambient concentration data are collected for a wide variety of pollutants. The most 

important of these in the VCAPCD are ozone (O3), fine particulate matter of a size of 

2.5 micrometers or less (PM2.5), and particulate matter of a size of 10 micrometers or 

less (PM10). Other pollutants measured include oxides of nitrogen (NOx, NO and 

NO2), total NMHC, Speciated PM2.5, Toxics (Cr6+, total metals and aldehydes) 

VOCs, and Carbonyls. Measurements of meteorological parameters is also 

conducted at all monitoring stations. Data for all of the pollutants is needed to better 

understand the nature of the ambient air quality in Ventura County, as well as to 

inform the public regarding the quality of the air. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 3 MONITORING DIVISION 

Not all pollutants are monitored at all stations. Most stations monitor for multiple 

pollutants, while some stations monitor only one or two pollutants. A particular 

station’s location and monitoring purpose determine the actual pollutants measured 

at that station. 

The majority of the population1

 resides in the southern half of Ventura County – the 

VCAPCD has focused its air monitoring efforts there. The south half of Ventura 

County is divided into six air monitoring regions: Ventura Coastal, Oxnard Plain, Ojai 

Valley, Santa Clara River Valley, Simi Valley, and the Conejo Valley. The 

VCAPCD’s air monitoring network has been designed to provide air monitoring 

coverage to those regions of Ventura County. 

Ventura Coastal - a coastal area, which covers 119 square miles and has a 

population of 234,275 people. The Ventura Coastal monitoring area represents an 

area that borders the Pacific Ocean, with Santa Barbara County to the west. This 

area encompasses the city of Port Hueneme and portions of the cities of Ventura and 

Oxnard. Some agricultural activities occur in the Ventura Coastal area. Emission 

sources within the area include a deepwater port and a number of Ventura County’s 

major stationary sources2

, including two natural gas-fired electric generating units, 

two naval bases and several natural gas-fired cogeneration facilities. In addition to 

stationary sources, the area is impacted by mobile sources and marine shipping 

operations occurring off of Ventura County’s coast. This area is served by the 

VCAPCD’s monitoring station at the Emma Wood State Park group campground, 

west of Ventura. 

Oxnard Coastal Plain – a broad coastal area from the Pacific Ocean to several inland 

valleys, covering 286 square miles and has a population of 198,970 people. The 

Oxnard Coastal Plain area is a relatively flat plain area with foothills and mountains at 

its northern border. The Oxnard Coastal Plain is home to considerable agricultural 

activities. Emission sources within the area include several of Ventura County’s 

major stationary sources, including natural gas-fired cogeneration facilities, several oil 

and gas production and processing facilities, and a paper products manufacturer. Its 

air quality is influenced by emission sources in the Ventura Coastal area that include 

a deepwater port, two natural gas-fired electric generating units, two naval bases, 

and several natural gas-fired cogeneration facilities. The area is impacted by marine 

shipping operations occurring off of Ventura County’s coast and mobile sources. 

This area is served by the VCAPCD’s monitoring station at Rio Mesa High School, 

Central Avenue, in Oxnard. 

 

1

 All population estimates in this document are based on the 2010 US census. 2

 For the purpose of this report a major stationary source is considered to be a facility that has been issued a federal Part 70

operating permit (also referred to as a Title V permit). 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 4 MONITORING DIVISION 

Ojai Valley – an inland area including the City of Ojai and the communities of 

OakView, and Meiners Oaks, which covers 102 square miles and is home to 27,784 

people. The Ojai Valley is surrounded by mountain ranges. There is one major 

stationary source on the southeastern edge of the region; however, it may be 

influenced by oil production activities occurring to the south, in the Ventura Coastal 

area. The area is impacted primarily by mobile sources. The Ojai Valley is served 

by the VCAPCD’s monitoring station at Ventura County fire station, Ojai Avenue, in 

Ojai. 

Santa Clara River Valley – an inland area, covering 204 square miles and home to 

45,107 people. The Valley is surrounded by foothills and low-lying mountains. The 

eastern edge of the Santa Clara River Valley is the border between Ventura and Los 

Angeles Counties. The area is also home to considerable agricultural activities. 

There are oil production and processing activities occurring throughout the Valley. 

There are two major stationary sources in its boundaries. The area is impacted 

primarily by mobile sources. This area is served by the VCAPCD’s monitoring station 

on Pacific Avenue, in Piru. 

Simi Valley – an inland area, which covers the cities of Simi Valley and Moorpark, is 

142 square miles and is home to 162,683 people. Simi valley is surrounded by 

foothills and low-lying mountains. The eastern edge of the Simi Valley is the border 

between Ventura and Los Angeles Counties. There are two major stationary sources 

in its boundaries. The area is impacted primarily by mobile sources. This area is 

served by the VCAPCD’s monitoring station at Simi Valley High School, on Cochran 

Street, in Simi Valley. 

Conejo Valley – an inland area, which includes the city of Thousand Oaks and the 

communities of Westlake Village and Newbury Park, covering 75 square miles and 

home to 153,680 people. The area is surrounded by foothills and low-lying 

mountains. The eastern edge of the Conejo Valley is the border between Ventura 

and Los Angeles Counties. There are no major stationary sources in its boundaries. 

The area is impacted primarily by mobile sources. This area is served by the 

VCAPCD’s monitoring station at Thousand Oaks High School, Moorpark Road, in 

Thousand Oaks. 

2.2 VCAPCD Monitoring Stations 

Figure 1 shows Ventura County’s air monitoring regions and the locations of the 

monitoring stations. Table 1 lists the pollutants measured in 2010 at each station, the 

region the station represents and the assigned Air Quality System (AQS) 

identification number for each monitoring station 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 5 MONITORING DIVISION 

Figure 1 – VCAPCD Monitoring Regions And Ambient Monitoring Stations 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 6 MONITORING DIVISION 

Table 1 -Air Monitoring Stations, Regions Served And Pollutants Monitored in 

2010 

Station Name AQS ID Pollutant Monitored 

El Rio – Rio 

Mesa School #2 

Region: Oxnard 

Coastal Plain 

061113001 Ozone, NO2, Total NMHC, PM10, Non-FEM BAM 

PM2.5, FRM PM2.5, VOCs, Carbonyls, Meteorology 

Ojai – Ojai 

Avenue 

Region: Ojai 

Valley 

061111004 Ozone, Non-FEM BAM PM2.5, PM10, Meteorology 

Piru – Pacific 

Avenue 

Region: Santa 

Clara River 

Valley 

061110009 Ozone, Non-FEM BAM PM2.5, FRM PM2.5, 

Meteorology 

Simi Valley – 

Cochran Street 

Region: Simi 

Valley 

061112002 Ozone, NO2, Total NMHC, PM10, Non-FEM BAM 

PM2.5, FRM PM2.5, Speciated PM2.5, Toxics (Cr6+, 

total metals and aldehydes) VOCs, Meteorology 

Simi Valley 

Upper Air Profiler 

061110008 Meteorology 

Thousand Oaks 

– Moorpark Road 

Region: Conejo 

Valley 

061110007 Ozone, non-FEM BAM PM2.5, FRM PM2.5, 

Meteorology 

Ventura – Emma 

Wood State 

Beach 

Region: Ventura 

Coastal 

061112003 Ozone, Meteorology 

The primary purposes of the VCAPCD’s air monitoring network are: (1) to determine 

Ventura County’s attainment status for the National and California standards for 

ozone, PM2.5 and PM10; (2) to track Ventura County’s air quality trends; (3) to provide 

information to the public about the quality of Ventura County’s air quality (i.e., 

reporting of the Air Quality Index and ozone episode forecasting), and; (4) for data in 

air quality modeling efforts. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 7 MONITORING DIVISION 

2.3 Monitoring Objectives And Spatial Scales 

As described by federal regulations, the monitoring objectives that the monitors in a 

monitoring network are to achieve include the following: 

1. To determine the highest concentration expected to occur in the area covered 

by the network; 

2. To determine representative concentrations in areas of high population 

density; 

3. To determine the impact on ambient pollution levels of significant sources or 

source categories; 

4. To determine general background concentration levels; 

5. To determine the extent of regional pollutant transport among populated 

areas, and in support of secondary standards. 

6. To determine the welfare-related impacts in more rural and remote areas 

(such as visibility impairment and effects on vegetation). 

The physical siting of an air monitoring station must achieve a spatial scale of 

representativeness that is consistent with the monitoring objective of the monitor. 

The spatial scale results from the physical location of the station with respect to the 

pollutant sources. It estimates the size of the area surrounding the monitoring station 

that experiences uniform pollutant concentrations. 

The categories of spatial scale are: 

1. Microscale - An area of uniform pollutant concentrations ranging from several 

meters up to 100 meters. 

2. Middle Scale - Uniform pollutant concentrations in an area of about 100 

meters to 0.5 kilometer. 

3. Neighborhood Scale - An area with dimensions in the 0.5 to 4.0 kilometer 

range. 

4. Urban Scale - Citywide pollutant conditions with dimensions ranging from 4 to 

50 kilometers. 

5. Regional Scale – A large area, usually rural, of the same general geography 

and without large sources that extends from tens to hundreds of kilometers. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 8 MONITORING DIVISION 

Table 2 - Monitoring Objectives And Appropriate Spatial Scales 

Monitoring Objective Appropriate Spatial Scale 

Highest concentration Micro, Middle, Neighborhood 

Population oriented Neighborhood or Urban 

Source Impact Micro, middle, neighborhood 

General/background levels Urban, regional 

Regional transport Urban, regional 

Welfare-related impacts Urban, regional 

Table 3 shows each of the VCAPCD’s air monitoring stations and its criteria pollutant 

objective and spatial scales. 

Table 3 – Pollutants, Monitoring Objectives And Spatial Scales 

Monitoring Objectives and Spatial Scale 

Pollutant Monitoring 

Station Highest 

Concentration Population Background Spatial Scale 

El Rio 9 Urban 

Ojai 9 Urban 

Piru 9 Urban 

Simi Valley 9 Urban 

Thousand 

Oaks 

9 Urban 

Ozone 

Ventura - 

Emma 

Wood 

 9 Neighborhood

El Rio 9 Urban 

NO2

Simi Valley 9 Urban 

El Rio 9 Neighborhood

Piru 9 Neighborhood

Simi Valley 9 Neighborhood

PM2.5

Thousand 

Oaks 

9 Neighborhood

El Rio 9 Neighborhood

Ojai 9 Urban 

PM10

Simi Valley 9 Neighborhood
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 9 MONITORING DIVISION 

2.4 Minimum Monitoring Requirements 

Certain monitoring requirements in 40 CFR 58 are based upon Metropolitan 

Statistical Areas (MSAs). MSAs are part of a population, economic and social-based 

classification of geographical regions developed by the U.S. Census Bureau. An 

MSA may include one or more counties. However, not all counties are within an 

MSA. The VCAPD contains a single MSA, the Oxnard-Thousand Oaks-Ventura 

MSA. 

40 CFR 58.10, Appendix D specifies the minimum requirements for air monitoring 

networks. As shown in Tables 4, through 10, the VCAPCD air monitoring network 

meets or exceeds the minimum monitoring requirements for ozone, PM2.5 and PM10

and PAMS. There are no minimum requirements for NO2, CO or SO2. 

2.4.1 Ozone 

Ventura County is a serious nonattainment area for ozone. The VCAPCD monitors 

for ozone at all six of its air monitoring stations. The NAAQS for ozone is based on 

the 4th highest annual 8-hour maximum average in parts per million (ppm) (level: 

.075) and was adopted by EPA on March 12, 2008. The ozone NAAQS is attained 

when the 4th highest annual maximum 8-hour average, averaged over three years is 

equal to or less than the level of the NAAQS at all monitoring stations. The level of 

the NAAQS has been exceeded at various monitoring stations in Ventura County. 

The ozone NAAQS is exceeded most frequently at Simi Valley, followed by Ojai and 

Piru. El Rio and Ventura-Emma Wood exceed the ozone NAAQS infrequently and 

record similar levels of ozone. 

County-wide ozone design values and the annual number of days exceeding the 

level of the NAAQS have continued to decline in spite of increasing population and 

vehicle miles in Ventura County. Ozone trends for each air monitoring station are 

shown in Appendix A. The 2010 county-wide 8-hour national design value is .086 

ppm, a decline from .132 ppm in 1985. In 2002 Ventura County attained the 1-hour 

ozone NAAQS with a 1-hour ozone national design value of .124 ppm. 

In 2010 the VCAPCD operated ozone monitors at six air monitoring stations in 

Ventura County. Table 4 contains the annual number of days exceeding the level of 

the NAAQS and the national design values, Figure 2 is a graph of historic ozone 

trends, the national design value (3 year average of 4th annual maximum 8-hour 

average). 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 10 MONITORING DIVISION 

Table 4 – Ozone: Number of Days > Than The Level Of The 8-Hour NAAQS and 

National Design Values 

Days > Level Of 8-Hour 

NAAQS 

National Design Values 

(3 Year Average Of 4th

Highest Annual Maximum) 

Air Monitoring 

Station 

2007 2008 2009 2010 2007 2008 2009 2010 

El Rio 0 0 1 0 .061 .061 .062 .063 

Ojai 4 12 11 7 .085 .083 .078 .079 

Piru 4 11 11 1 .081 .080 .080 .079 

Simi Valley 19 27 24 8 .088 .088 .087 .086 

Thousand Oaks 2 6 5 6 .075 .075 .077 .078 

Ventura 1 0 0 0 .063 .064 .064 .063 

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

0.15

1988

1990

1992

19941996

1998

2000

2002

2004

20062008

2010

Ozone in Parts per Million

Figure 2- Historic Ozone Trends: National Design Value (3 Year Average Of 4th

Highest Annual Maximum 8-Hour Average) 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 11 MONITORING DIVISION 

As shown in Table 5 the VCAPCD’s air monitoring network exceeds the minimum 

monitoring requirement for ozone established in 40 CFR Part 58. 

Table 5 – Ozone: Minimum Monitoring Requirements 

MSA Population 

(2010) 

8-Hour 

Design 

Value 

(2010) 

Min. # 

Monitors 

Required 

# 

Monitors 

Active 

# 

Monitors 

Needed 

OxnardThousand 

Oaks-Ventura 

MSA 

822,499 .086 2 5* 0 

*This number reflects the discontinuation of ozone monitoring at Ventura-Emma Wood State Beach April 28, 2011. 

2.4.2 PM2.5

The VCAPCD’s PM2.5 monitoring network consists of four stations using FRM PM2.5

monitors and five stations using continuous Non-FEM Beta-Attenuation Method 

(BAM) PM2.5 monitors. The 24-hour NAAQS for PM2.5 is based on the 98th 

percentile 24-hour average, in μg/m3 (level: 35). The annual PM2.5 NAAQS is based 

on the annual weighted mean of the 24-hour averages, in μg/m3 (level: 15). Table 6 

and Table 7 contain annual PM2.5 statistics for Ventura County. 

Table 6 - PM2.5: Annual 98th Percentile 24-Hour Averages And 24-Hour National 

Design Values 

Annual 98th Percentile 24-

Hour Averages Air Moitoring 24-Hour Design Values 

Station 2007 2008 2009 2010 2007 2008 2009 2010 

El Rio 27.5 19.7 18.9 16.5 25 24 22 18 

Piru 22.3 17.0 18.8 16.3 21 20 19 17 

Simi Valley 31.8 25.7 20.5 17.4 29 28 26 21 

Thousand Oaks 24.9 20.7 21.1 21.3 24 23 22 21 

Table 7 - PM2.5: Annual Weighted Means And Annual National Design Values 

Air Moitoring Annual Weighted Means Annual Design Values 

Station 2007 2008 2009 2010 2007 2008 2009 2010 

El Rio 10.6 10.1 10.2 8.7 10.3 10.2 10.3 9.6 

Piru 10.2 9.8 9.5 8.5 9.6 9.8 9.8 9.2 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 12 MONITORING DIVISION 

Air Moitoring Annual Weighted Means Annual Design Values 

Station 2007 2008 2009 2010 2007 2008 2009 2010 

Simi Valley 11.7 10.7 10.3 8.7 11.1 10.9 10.9 9.9 

Thousand Oaks 10.5 10.3 10.7 8.5 10.3 10.2 10.5 9.9 

Table 8 shows that the VCAPCD’s air monitoring network exceeds the minimum 

monitoring requirements established in 40 CFR Part 58 for PM2.5. 

Table 8 - PM2.5: Minimum Monitoring Requirements 

MSA 

Population 

(2010) 

Ann. 

Design 

Value 

(2010) 

24-Hr 

Design 

Value 

(2010) 

# Monitors 

Required 

# 

Monitors 

Active 

# 

Monitors 

Needed 

OxnardThousand 

OaksVentura 

MSA 

822,499 9.9 21 1 5* 0 

*This number reflects the pending initiation of FEM PM2.5 monitoring at Ojai-Ojai Avenue January 1, 2012. 

2.4.3 PM10

For PM10, the annual maximum 24-hour average in Ventura County during the years 

2000 through 2010 is 248 μg/m3 (10/21/2007). However, this average has been 

flagged as an exceptional event. Documentation has been submitted to EPA 

through CARB to justify that this exceedance was an exceptional event. The next 

highest average in the years 2000 through 2010 is 169 μg/m3 (11/23/2003). The 

PM10 data for the 24-hour NAAQS in μg/m3 (level: 150) is shown Table 9. 

Table 9 – PM10: Annual Maximum 24-Hour Averages And 3-Year Average Of 

Annual Estimated Exceedances 

Annual Maximum 24-Hour 

Averages 

3- Year Average of Annual 

Estimated Exceedances Air Monitoring 

Station 2007 2008 2009 2010 2007 2008 2009 2010 

El Rio 248* 80 100 62 0 0 0 0 

Ojai 99* 61 38 45 0 0 0 0 

Simi Valley 117* 80 753 314 2 2 2 0 

*Flagged as an “Exceptional Event” 

 

3

 The annual maximum 24-hour average from the collocated sampler was 77 4

 The annual maximum 24-hour average from the collocated sampler was 34 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 13 MONITORING DIVISION 

Table 10 shows that the VCAPCD’s air monitoring network exceeds the minimum 

monitoring requirements for PM10 established in 40 CFR Part 58. 

Table 10 - PM10: Minimum Monitoring Requirements 

MSA Population 

(2010) 

Min. # 

Monitors 

Required 

# Monitors 

Active 

# Monitors 

Needed 

Oxnard-Thousand 

Oaks-Ventura MSA 822,499 1 - 2 2* 0 

*This number reflects the discontinuation of FRM PM10 monitoring at Oai-Ojai Avenue on December 31, 2011. 

2.4.4 PAMS 

The Photochemical Assessment Monitoring System (PAMS) program provides more 

comprehensive data on ozone air pollution in areas classified as serious, severe or 

extreme nonattainment for ozone than would otherwise be achieved through the 

SLAMS monitoring stations. 

The PAMS program includes measurements for ozone, oxides of nitrogen, speciated 

VOCs, trace CO, NOy, continuous non-methane hydrocarbon (NMHC) and 

meteorology. 40 CFR 58, Appendix D, Section 5 specifies the network design for the 

PAMS program. We have not installed the trace CO and NOy instrumentation due to 

wide spread questioning by Federal and state air agency staff of the rationale of 

monitoring NOy and trace CO in Southern California.. Additionally, any changes to 

our existing PAMS network are on hold until EPA updates the requirements for the 

PAMS program as advised by EPA Region 9 in an April 28, 2011 email from 

Meredith Kurpius, PhD, Air Division. In 2010 the VCAPCD’s PAMS monitoring 

network was comprised of the Ventura (Type 1), El Rio (Type 2) and Simi Valley 

(Type 3) air monitoring stations. Ventura County is now required to operate one 

each of a Type 2 and 3 PAMS site. 

The VCAPCD operates its PAMS program according to the California Alternative 

Plan (CAP III). Under CAP III the sampling cannister sampling schedule is every 

third day during the months of July August and September. Additionally, the 

VCAPCD operates its PAMS program on days that the maximum 8-hour average 

ozone is predicted to exceed .075 ppm. 

2.4.5 Carbon Monoxide 

The VCAPCD previously operated monitors to measure levels of CO at the El Rio 

and Simi Valley monitoring stations. Because of the low levels recorded, CO 

monitoring at these stations was discontinued in March and July 2004. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 14 MONITORING DIVISION 

40 CFR 58, Appendix D, Section 4.2 states that there are no minimum requirements 

for the number of CO monitoring sites. There are no CO monitors required for SIP or 

maintenance planning. 

2.4.6 Nitrogen Dioxide 

The VCAPCD previously operated monitors to measure levels of nitrogen dioxide 

(NO2) at the Ojai, Ventura and Thousand Oaks monitoring stations. Because of the 

low levels recorded, NO2 monitoring at these stations was discontinued in July 2004. 

The VCAPCD currently monitors for NO2 at El Rio and Simi Valley monitoring 

stations. 

40 CFR 58, Appendix D, Section 4.3 states that there are no minimum requirements 

for the number of NO2 monitoring sites. There are no NO2 monitors required for SIP 

or maintenance planning. 

2.4.7 Sulfur Dioxide 

The VCAPCD previously operated a monitor to measure sulfur dioxide (SO2) at the 

El Rio monitoring station. Because of the low levels recorded, SO2 monitoring was 

discontinued in July 2004. 

40 CFR 58, Appendix D, Section 4.4 states that there are no minimum requirements 

for the number of SO2 monitoring sites. There are no SO2 monitors required for SIP 

or maintenance planning. 

2.5 Local Monitoring Objectives And Local Spatial Scales 

Each of the VCAPCD’s air monitoring stations has at a minimum an ozone monitor. 

Monitors at some stations include FRM PM2.5 monitors, continuous non FEM PM2.5

BAM monitors, FRM PM10 monitors and monitors for continuous NMHC, and oxides 

of nitrogen (NO, NOX, NO2). The VCAPCD has located each of its air monitoring 

stations in relation to specific geographic areas of Ventura County (Section 2.1), 

depending upon each area’s population, topography and meteorology. Because the 

north-half of Ventura County is mountainous and sparsely populated (819 people), 

no air monitoring stations are located in that area. Because the VCAPCD has 

designed its network with consideration given to the distinct geographic, topographic 

and meteorological areas of Ventura County, the areas and population served by the 

VCAPCD’s air monitoring stations vary greatly. The local monitoring objective for 

VCAPCD’s monitoring stations is reporting the Air Quality Index (AQI) and for ozone 

episode forecasting. The local spatial scale for VCAPCD’s monitoring stations is 

regional as previously described. Table 11 contains the local regions and population 

served by each of its air monitoring stations. 
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VENTURA COUNTY APCD 15 MONITORING DIVISION 

Table 11 - Local Air Monitoring Regions - Area and Population Served 

Station Name and 

Region Served AQS ID Area Served (Sq. Miles) 

Population 

Served 

Population 

Density 

(Pop./Sq. Mi) 

El Rio – Rio Mesa 

School #2 

Region: Oxnard 

Coastal Plain 

061113001 286 198,970 1025 

Ojai – Ojai Avenue 

Region: Ojai Valley 061111004 102 27,784 300 

Piru – Pacific 

Avenue 

Region: Santa 

Clara River Valley 

061110009 204 45,107 180 

Simi Valley – 

Cochran Street 

Region: Simi Valley 

061112002 142 160,576 1131 

Thousand Oaks – 

Moorpark Road 

Region: Conejo 

Valley 

061110007 75 153,680 2000 

Ventura – Emma 

Wood State Beach 

Region: Ventura 

Coastal 

061112003 119 234,275 1568 
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VENTURA COUNTY APCD 16 MONITORING DIVISION 

3 Recent And Pending Modifications To The Air Monitoring 

Network 

40 CFR 58.14(b) requires that the EPA review and approve modifications to a 

SLAMS monitoring network, and requires the responsible state or local agency to 

inform the EPA of any proposed modifications. This provides an opportunity for 

review and comment on the possible regulatory consequences of such action. 

Furthermore, the VCAPCD generally would conduct a period of parallel sampling of 

monitors or if a station is moved, at the current station and the proposed station for a 

term of several months to one year, depending upon the pollutant, the NAAQS that is 

of most concern, and on other factors. In order to make more effective use of 

VCAPCD resources, consideration is being given to reducing some operations of the 

monitoring network and making changes in our monitoring methods in the coming 

year(s). 

The monitoring methods for particulate matter (PM2.5 and PM10) are currently going 

through a transition. During the coming year the VCAPCD will begin the transition 

from the manual collection of particulates on a filter over a 24 hour period to 

automated continuous particulate monitors. The new monitoring method will allow us 

to monitor more efficiently and effectivley by providing continuous data and 

eliminating the processing of filters, 

The VCAPCD is also rehabilitating our air monitoring network by replacing 

instrumentation due to the analyzer and equipment problems that have developed 

over the years. With the initial establishment of the PAMS program in the mid 

1990’s, equipment was purchased to meet its goals. Over the past 15 years the 

equipment has aged and exceeded their 5 year life spans. Our in-house technical 

expertise was able to extend those life spans to more than 10 years, but that 

equipment has finally failed and is now being replaced. 

As our entire economy and governmental agencies face the reality of doing more 

with less resources, we are trying to maximize efficiency. We are improving our data 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 17 MONITORING DIVISION 

acquisition system by adding the capability to connect to individual air quality 

analyzers from the office minimizing the need to travel to the air monitoring stations 

as often. We are also updating our data management system giving our data and 

station technicians more capabilities to automate the collection and processing of air 

quality and quality assurance data. 

Additional changes are forthcoming. EPA is requiring the establishment of near-road 

NO2 monitoring by 2013. Our PAMS program is on hold until EPA annouces new 

monitoring requirements later this year to reshape and refocus the PAMS program. 

We are continuing to perform sampling for the Speciation Trends Network, while 

working with EPA on scheduling and quality assurance improvements. 

3.1 Discontinued Monitoring Station – Ventura–Emma Wood State 

Beach 

As Ventura County’s air quality continues to improve, El Rio ozone concentrations 

have shown to be representative of Ventura Coastal region ozone within a few ppb. 

Due to the ongoing costs of operating the Ventura station and due to siting issues the 

Ventura station discontinued monitoring on April 28, 2011. A letter requesting 

closure of the Ventura-Emma Wood State Beach air monitoring station was sent to 

EPA Region 9 on March 3, 2011. Our request was approved by EPA Region 9 in a 

letter from Matthew Lakin, Manager Air Quality Analysis Office, dated April 4, 2011. 

The station was closed following the CARB’s annual performance audit (April 27, 

2011). 

3.2 Pending Changes To The PM2.5 Monitoring Network 

As shown in Section 2.4.2, VCAPCD operates five FRM PM2.5 samplers at four 

monitoring stations (one sampler is collocated at the Thousand Oaks monitoring 

station). The first step in changing PM2.5 monitoring methods is to replace the 

VCAPCD’s current automated continuous non-FEM PM2.5 Beta Attenuation Method 

(BAM) monitors with automated continuous PM2.5 BAM monitors that have been 

designated a Federal Equivalent Method (FEM) ) at Piru, Thousand Oaks and El Rio 

and to initiate a continuous PM2.5 BAM FEM monitor at Ojai. The FEM PM2.5 monitors 

have been ordered and we anticipate installing them during July and August 2011. 

By January 1, 2012, the VCAPCD will discontinue FRM PM2.5 sampling at Piru and 

and the primary FRM PM2.5 at Thousand Oaks. At Simi Valley we will continue 

monitoring PM2.5 with a FRM PM2.5 sampler on a 1 in 3 schedule. The Simi Valley 

FRM PM2.5 will continue to be our National Design Value monitor. The non-FEM 

PM2.5 BAM will continue operation at Simi Valley to provide AQI and episode data.
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 18 MONITORING DIVISION 

Beginning on January 1, 2012 the VCAPCD will initiate a year long comparative 

study establishing the relationship between our current manual FRM PM2.5 samplers 

and the new automated continuous FEM PM2.5 BAM monitors at a near coastal 

station, El Rio, and at an inland valley station, Thousand Oaks. We will continue 

operating the FRM PM2.5 samplers on their current schedules through the end of 

2011 to provide for annual data completeness 

The tables below are a summary of changes to our PM2.5 monitoring network for CY2012, the year of the comparison study and for the final pending PM2.5 monitoring 

network as it will be configured in CY-2013. 

Table 12 – CY-2012 PM2.5 Comparison Study 

Station FRM PM2.5

FRM PM2.5

Collocated Non-FEM PM2.5 FEM PM2.5

El Rio 1 in 6* Discontinued Initiated/Primary* 

Ojai Valley Initiated/Primary 

Piru Discontinued Discontinued Initiated/Primary 

Thousand 

Oaks Discontinued 1 in 6* Discontinued Initiated/Primary* 

Simi Valley Primary/1 in 

3/DV 

Continued/AQIEpisode 

*Monitors in Comparison Study 

Sampling Schedule Changes from CY-2011 

• El Rio FRM 2.5 changed from 1 in 3 to 1 in 6 

Table 13 – CY-2013 Pending Final PM2.5 Network 

Station FRM PM2.5

FRM PM2.5

Collocated Non-FEM PM2.5

FEM 

PM2.5

El Rio Discontinued Primary 

Ojai Valley Primary 

Piru Primary 

Thousand 

Oaks 1 in 12* Primary 

Simi Valley Primary/1 in 

3/DV 

Continued/AQIEpisode 

Sampling Schedule Changes from CY-2012 

• Thousand Oaks FRM 2.5 Collocated changed from 1-6 to 1-12 

3.3 Pending Changes To The PM10 Monitoring Network 

As shown in Section 2.4.3, VCAPCD operates four FRM PM10 samplers at three air 

monitoring stations (El Rio, Simi Valley, Ojai). There are two FRM PM10 samplers at 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 19 MONITORING DIVISION 

Simi Valley, one is collocated. Two FEM PM10 BAM monitors will be ordered in July 

2011. These monitors will be installed at El Rio and Simi Valley in October 2011. At 

Ojai, the FRM PM10 sampler will be discontinued with the installation of the FEM 

PM2.5 BAM. 

Beginning on January 1, 2012, the VCAPCD will initiate a year long comparative 

study establishing the relationship between our current manual FRM PM10 samplers 

and the new automated continuous FEM PM10 BAM monitors at Simi Valley. We will 

continue operating the FRM PM2.5 samplers on their current schedules through the 

end of 2011 to provide for annual data completeness 

The tables below are a summary of changes to our PM10 monitoring network for CY2012, the year of the comparison studies and for the final pending PM10 network as it 

will be configured in CY-2013. 

Table 14 – CY-2012 PM10 Comparison Study 

Station FRM PM10 FRM PM10 Collocated FEM PM10

El Rio Discontinued Initiated/Primary 

Ojai Valley Discontinued 

Simi Valley Discontinued 1 in 6* Initiated/Primary*/DV 

* Monitors in Comparison Study 

Table 15 – CY-2013 Pending Final PM10 Network 

Station FRM PM10

FRM PM10

Collocated FEM PM10

El Rio Primary 

Simi Valley 1 in 12 Primary/DV 

Sampling Schedule Changes from CY-2012 

• Simi Valley FRM PM10 Collocated changed from 1 in 6 to 1 in 12 

3.4 Pending Changes To The PAMS Network 

40CFR58 Appendix D, Section 5 specifies the network design for the PAMS 

program. Federal regulation require the addition of NOy monitoring at type 3 sites 

(Simi Valley) and trace CO monitoring at type 2 sites (El Rio). We have not installed 

the instrumentation due to wide spread questioning by Federal and state air agency 

staff of the rationale of monitoring NOy and trace CO in Southern California.. 

Additionally, any changes to our existing PAMS network are on hold until EPA 

updates the requirements for the PAMS program as advised by EPA Region 9 in an 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 20 MONITORING DIVISION 

April 28, 2011 email from Meredith Kurpius, PhD, Air Division. As previously stated, 

the Ventura monitoring station was discontinued on April 28, 2011. The Ventura 

monitoring station is not needed for PAMS, only site type 2 and 3 are required. The 

2005 ozone season was the last time VOC canisters were collected at the Ventura 

monitoring station due to sampler failure. The Ventura monitoring station was a 

sentinel site, meaning only if ozone was forecast to be above the NAAQS were 

cannisters collected. El Rio and Simi Valley collect cannisterss on a 1 in 3 day 

schedule during July, August, and September, pursuant to the California Alternative 

Plan III. 

Continuous NMHC monitoring is required at site types 2 and 3. Our NMHC 

analyzers failed last year. We have two NMHC analyzers on order and expect to 

have them installed and operational in July 2011. 

In July 2011 we will be ordering a gas chromatograph to provide additional analysis 

capability for our lab staff to analyze for Volatile Organic Compounds (VOC). The 

new gas chromatograph should be installed in late Fall 2011. 

The atmospheric profiler failed in November 2010. VCAPCD staff has done 

extensive research to get the atmospheric profiler repaired. A major upgrade to the 

atmospheric profiler equipment will be made this summer, and we anticipate the 

atmospheric profiler to be operational in Fall 2011. 

3.5 Pending Changes To The NO2 Network 

In 2010 EPA adopted a new NAAQS for nitrogen dioxide (NO2). MSA’s with a 

population greater than 500,000 are required to establish an ambient NO2 near road 

site by January 1, 2013. As a result, VCAPCD will establish an ambient NO2 near 

road monitoring site along US Highway 101 (The Ventura Freeway), in Thousand 

Oaks between Hampshire Road and Westlake Village Road. 

3.6 Status Of SO2

On June 2, 2010, EPA established a new 1-hour SO2 NAAQS, effective August 23, 

2010, which is based on the 3-year average of the annual 99th percentile of 1-hour 

daily maximum averages in ppb (level: 75). MSA’s with a population-weighted 

emission index (PWEI) greater than a threshold would be required to establish an 

ambient SO2 monitoring program by January 1, 2013. On May 27, 2011 EPA Region 

9 issued an email from Meredith Kurpius, PhD, Air Division, stating that “EPA did not 

expect Ventura County to have any additional SO2 monitoring requirements based 

on the 2008 NEI”. Therefore, based on the 2008 NEI (National Emissions Inventory), 

Ventura County fell below the PWEI threshold releasing the VCAPCD from the need 
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VENTURA COUNTY APCD 21 MONITORING DIVISION 

to monitor SO2. 

3.7 Status Of Lead 

In 2008 EPA revised the NAAQS for lead from 1.5 μg/m3

 to 0.15 μg/m3. The 

regulation requires that state and local agencies establish an ambient lead monitor 

by January 1, 2011. In December 2009 EPA proposed revisions to the regulation 

that revise “source oriented” monitoring requirements. As a result of EPA’s revisions, 

and EPA’s recent acceptance of the VCAPCD’s lead emission inventory for airports, 

the VCAPCD will not be subject to the lead monitoring requirements. 

3.8 Proposed Changes To The Speciation Trends Network (STN) 

As part of the PM2.5 monitoring network, VCAPCD operates a speciation monitor at 

the Simi Valley air monitoring station. Samples collected from the speciation sampler 

are analyzed by an EPA contractor. The SASS samplers (Speciation Air Sampling 

System and URG carbon sampler), are maintained by VCAPCD for EPA. SASS and 

URG filters are sent to VCAPCD to be run and then returned on a tight schedule to 

an EPA contractor for analysis. VCAPCD has had difficulty meeting the receiving, 

run, and pickup schedules set by the EPA. Our discussion of these issues with EPA 

Region 9 revealed this to be common problem. EPA Region 9, the EPA’s contractor, 

and VCAPCD will be refining these sampling procedures and schedules in 2012. 

3.9 Pending Changes To The Data Acquisition And Management 

System 

From July to October 2011 we will work on improving our connectivity issues 

between the air monitoring analyzers and our office. We are acquiring more 

sophistcated analyzers that can be interrogated remotely to reduce travelling time to 

the air monitoring stations. We have hired a contractor to establish the greater 

connectivity capability. Included is an upgrade to our data acquisition and 

management system. 
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VENTURA COUNTY APCD 22 MONITORING DIVISION 

4 Required Quality Assurance Of The Monitoring Program 

This section demonstrates compliance with the quality assurance requirements of 40 

CFR 58 Appendices A, C, and E. This information is required in annual network 

plans. 

Annually, CARB’s Quality Assurance (QA) Section conducts quality assurance 

performance evaluations (audits) for each nitrogen dioxide analyzer, ozone analyzer 

and particulate sampler in the network with National Institute of Standards and 

Technology (NIST) traceable gases and calibrators. The monitors are calibrated on 

a biannual schedule with separate standard equipment. Flow standards are NISTtraceable and recertified annually. 

As part of the annual CARB QA Section audit at each air monitoring station, CARB 

QA Section staff conduct siting evaluations. Physical measurements and 

observations, including probe/sensor height above ground level, distance from trees, 

type of ground cover, residence time, obstructions to air flow, and distance to local 

sources, topography, vehicle counts, predominant wind direction, probe material, 

etc., are taken to determine compliance with 40 CFR 58, Appendix E requirements. 

Quality Assurance Site Information along with photographs of the monitoring stations 

are available on the CARB website at 

http://www.arb.ca.gov/qaweb/countyselect.php?c_arb_code=56 . 

Ozone audits are performed by CARB QA Section staff using dedicated ozone 

transfer standards (API 400 Series) and biannual calibrations are performed by 

VCAPCD staff using dedicated ozone transfer standards (API 400 Series) that are 

certified quarterly with a laboratory API 400 E ozone primary standard that is itself 

certified annually by the CARB with referencing to a NIST-referenced ozone 

photometer. 

FRM PM2.5 samplers are audited annually by the CARB QA Secton, some are 

audited by EPA contractor, and all are calibrated biannually by VCAPCD staff. Each 

program uses separate equipment that includes BGI deltaCal and triCal digital flow 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD 23 MONITORING DIVISION 

calibrators which are certified against NIST-traceable primary standards. VCAPCD 

staff also perform monthly flow, pressure and temperature checks on FRM PM2.5

samplers using certified/referenced instruments. (Note: The CSN samplers, SASS 

and URG are not audited.) 

PM10 sampler flow rate audits are conducted annually by the CARB QA Section and 

by EPA contractor, while the PM10 sampler flow rate calibrations are done biannually 

by VCAPCD staff. Both are conducted with dedicated instruments that include BGI 

Hi-Vol Calibrators that are certified annually to NIST. PM10 flow rates are checked 

monthly against a separate standard by VCAPCD staff. 

NO2 audits are performed by CARB QA Section staff using dedicated multi-gas 

calibrators, and calibrations are performed biannually by VCAPCD staff using 

Environics S-9100 multi-gas calibrators. 

Meteorological audits are conducted by CARB QA Section staff with instruments that 

are NIST-traceable and/or manufacturer-certified. Calibrations are performed by 

VCAPCD staff triannually with NIST-referenced or NIST-traceable standards. 

The PAMS-VOC program participated in an EPA Region 9 audit. VCAPCD plans to 

participate in Region 9’s annual performance evaluation. The PAMS-Carbonyls 

program participates in biannual Performance Evaluations overseen by the EPA. All 

of the programs (PAMS-VOC’s, PAMS-Carbonyls), are all calibrated with NISTreferenced standards. 

The VCAPCD’s gravimetric laboratory is audited annualy by CARB QA Section staff 

with NIST-referenced or NIST-traceable standards. The balances are certified 

annually by a contractor using NIST-referenced or NIST-traceable standards and the 

mass standards are certified biannually by a contractor using NIST-referenced or 

NIST-traceable standards. 

Approximately every five years, the EPA conducts a Technical Systems Audit (TSA) 

of the VCAPCD’s air quality monitoring network and procedures (the last TSA was in 

May of 2004). The audits examine all aspects of the VCAPCD’s gravimetric 

laboratory and field monitoring and data processing operations. The TSA is to 

determine if VCAPCD’s air monitoring program satisfies the requirements of 40 CFR 

58 and EPA's Quality Assurance Handbook for Air Pollution Measurement Systems, 

Volume II. Compliance with these regulations is necessary for data to be considered 

data-for-record per the California Code of Regulations (Title 17, Article 3, section 

70301). Data meeting these requirements are eligible to be submitted to EPA’s AQS 

database and be used for regulatory actions taken pursuant to the Federal Clean Air 

Act and the California Clean Air Act.
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VENTURA COUNTY APCD 24 MONITORING DIVISION 

5 Data Submission Requirements 

5.1 Air Quality Data 

VCAPCD’s air monitoring stations report data to the EPA’s AQS database. The data 

generated at these stations are public information and are available in various 

formats from the respective agencies. Table 16 lists some sources for air quality 

data. 

Table 16 - Sources Of Ambient Air Quality Data 

Agency 

Address For 

Data 

Requests 

Internet Address Data 

Available 

Ventura County 

APCD 

669 County 

Square Drive 

Ventura, CA 

93003 

http://www.vcapcd.org/ Ventura 

County 

California Air 

Resource 

Board 

PO Box 2815 

Sacramento, 

CA 95812 

http://www.arb.ca.gov/html/ds.htm 

California Air 

Monitoring 

Data 

United States 

Environmental 

Protection 

Agency 

Ariel Rios 

Building 

1200 

Pennsylvia 

Avenue, N.W. 

Washington, 

DC 20460 

http://www.epa.gov/air/data/ 

National Air 

Monitoring 

Data 

Real time air quality and meteorological data is available on CARB’s Air Quality and 

Meteorological Information System at http://www.arb.ca.gov/aqmis2/aqmis2.php . 

Federal regulations require that air monitoring organizations submit precision and 
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VENTURA COUNTY APCD 25 MONITORING DIVISION 

accuracy data for the data reported to AQS. VCAPCD air monitoring precision data 

are submitted to the EPA AQS database on a quarterly basis and are up to date as 

of the publication of this report. Accuracy data are reported to the EPA by CARB. 

Federal regulations require the air monitoring organizations to annually submit a 

letter certifying that ambient data and quality assurance data are completely 

submitted to AQS and that the ambient data are accurate to the best of our 

knowledge taking into consideration the quality assurance findings. VCAPCD’s 2010 

annual data certification was submitted to EPA on 4/27/2011. 
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VENTURA COUNTY APCD MONITORING DIVISION 

Appendix A 

Detailed Station Information
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VENTURA COUNTY APCD A-1 MONITORING DIVISION 

Detailed Station Information 

El Rio – Rio Mesa School #2 

The El Rio air monitoring station is located 7 miles inland in the broad Oxnard Plain 

area, covering 286 square miles and home to 198,970 people– approximately 24.2 

percent of Ventura County’s population. In 2010 the VCAPCD operated samplers to 

collect ambient data for ozone, PM10, PM2.5, continuous PM2.5, nitrogen dioxide, 

NMHC, VOC (canisters), and carbonyls. The VCAPCD also collects meteorological 

measurements at the station (wind speed, wind direction, temperature, relative 

humidity, solar radiation, and precipitation). 

The VCAPCD has conducted oxidant and ozone sampling in the Ventura/Oxnard 

Plain area since 1969. The VCAPCD also has monitored for particulate matter in the 

Ventura/Oxnard Plain area since 1971. 

Ozone 

Typically, this station records the lowest 1- and 8-hour ozone levels in Ventura 

County. The station’s annual maximum 1-hour ozone average has been reduced 

from .190 ppm in 1989 to .083 ppm in 2010. In 2010 the station’s 4th highest annual 

maximum 8-hour average was .062 ppm and the annual maximum 8-hour average 

was .073 ppm. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-2 MONITORING DIVISION 

Figure 3 - Ozone Trends Summary: El Rio-Rio Mesa School #2 

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available on CARB’s AQ Statistics database for this station from 1980 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The national 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect. 

PM2.5 

This station has not exceeded the 24-hour NAAQS or the annual NAAQS for PM2.5. 

In 2010 the station’s annual 98th percentile maximum 24-hour average was 16.5 

μg/m3 and the annual weighted mean was 8.5 μg/m3

. 

Table 17 – El Rio PM2.5 Annual Maximum Averages 

Annual 98th Percentile 24-Hour Averages Annual Weighted Means 

2007 2008 2009 2010 2007 2008 2009 2010 

27.5 19.7 18.9 16.5 10.6 10.1 10.2 8.5 

PM10

In 2007 this station exceeded the 24-hour PM10 NAAQS with a average of 248 μg/m3

. 
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VENTURA COUNTY APCD A-3 MONITORING DIVISION 

This average occurred during a major wildfire in Ventura County and has been 

flagged as an exceptional event. The VCAPCD has submitted this information to 

U.S. EPA, through CARB, to have this average excluded. In 2010 the station’s 

annual maximum 24-hour average was 62 μg/m3

. Note that in December 2006 EPA 

revoked the PM10 annual NAAQS. 

Table 18 – El Rio PM10 Annual Maximum 24-Hour Averages 

Annual Maximum 24-Hour Averages 

2007 2008 2009 2010 

248* 80 100 62 

*Flagged as an “Exceptional Event” 

PAMS 

The El Rio monitoring station is a Type 2 PAMS site and has operated since 1994. 

During the period of July 1 through September 30 of each year the VCAPCD 

operates this station according to established EPA protocols for PAMS monitoring 

and the CAP III protocol. 40CFR58 Appendix D, Section 5 specifies the network 

design for the PAMS program. Federal regulation require the addition of trace CO 

monitoring at type 2 sites. We have not installed the instrumentation due to wide 

spread questioning by Federal and state air agency staff of the rationale of 

monitoring trace CO in Southern California.. Additionally, any changes to our existing 

PAMS network are on hold until EPA updates the requirements for the PAMS 

program.

Table 19 – El Rio Station Information 

Station Name > El Rio – Rio Mesa School #2 

AQS ID 061113001 

Grid Coordinates Latitude: 34o 15’ 8” Longitude:119o 8’ 35” 

Location On school grounds 

Address 545 Central Ave, Oxnard CA 93036 

County Ventura County 

Location Type Suburban 

Dist. to road 75 meters 

Traffic count 5,000 vehicles/day 

Groundcover Paved/asphalt 

PEP audit September 2010 (EPA Contractor) 

Flow audit April 2011 (CARB) 

Representative Area Oxnard Coastal Plain 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-4 MONITORING DIVISION 

Table 20 – El Rio Monitor Information 

Pollutant > Ozone Non-FEM BAMPM2.5PM10-SSI 

Monitor Designation PAMS/ SLAMS N/A SLAMS 

Monitor objective Population 

exposure 

N/A Population 

exposure 

Spatial scale Urban Scale Neighborhood Urban Scale 

Sampling method API/Teledyne 400 Met One 1020 

BAM 

Anderson 

SA1200 

Analysis method Ultraviolet 

Absorption Beta Attenuation Size selective inlet 

Start date 01/01/1979 01/01/2005 04/03/1988 

Operation schedule Continuous Continuous 1-in-6 days 

Sampling season Year-round Year-round Year-round 

Probe height 4.3 meters 4.7 meters 5.5 meters 

Distance from supporting 

structure 1.2 meters 1.7 meters 1.9 meters 

Distance from obstructions 

on roof None None None 

Distance from obstructions 

not on roof None None None 

Distance from trees 15 meters 15 meters 15 meters 

Distance between 

collocated monitors N/A N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material Borosilicate glass & 

FEP Teflon N/A N/A 

Residence time 7.5 seconds N/A N/A 

Will there be changes 

within the next 18 months? No Yes5

 No 

Is it suitable for 

comparison against the 

annual PM2.5? 

N/A No N/A 

 

5

 See Section 3.2 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-5 MONITORING DIVISION 

Pollutant > FRM PM 2.5 Nitrogen Dioxide VOCs 

Monitor 

Designation SLAMS PAMS/SLAMS Type 2 PAMS/SLAMS 

Monitor objective Population 

exposure 

Population 

exposure High concentration 

Spatial scale Neighborhood Urban Scale 

Sampling 

method 

Partisol-Plus 

Model 2025 

Sequential Air 

Samplers 

API 200A 

Xontech 910PC 

Integrated grab 

sampling 

Analysis method Size selective inlet Chemiluminescent Laboratory gas 

chromatography 

Start date 01/01/1999 01/01/1980 1994 

Operation 

schedule 1-in-3 days Continuous 

1-in-3 days and days 

in which ozone is 

predicted to exceed 

0.075 ppm 

Sampling 

season 

Year-round Year-round July 1 through 

September 30 

Probe height 5.5 meters 4.3 meters 4.3 meters 

Distance from 

supporting 

structure 

1.9 meters 1.2 meters 1.2 meters 

Distance from 

obstructions on 

roof 

None None None 

Distance from 

obstructions not 

on roof 

None None None 

Distance from 

trees 

Distance 

between 

collocated 

monitors 

N/A N/A N/A 

Unrestricted 

airflow 360 degrees 360 degrees 360 degrees 

Probe material N/A Borosilicate glass & 

FEP Teflon 

Borosilicate glass & 

FEP Teflon 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-6 MONITORING DIVISION 

Pollutant > FRM PM 2.5 Nitrogen Dioxide VOCs 

Residence time N/A 8.8 seconds 

Will there be 

changes within 

the next 18 

months? 

Yes6

 No No 

Is it suitable for 

comparison 

against the 

annual PM2.5? 

Yes N/A N/A 

Figure 4 – Map Showing Location Of El Rio – Rio Mesa School #2 

 

6

 See Section 3.2 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-7 MONITORING DIVISION 

Detailed Station Information 

Ojai – Ojai Avenue 

The Ojai air monitoring station is located 14 miles from the coast in the Ojai Valley 

area, which covers 102 square miles and is home to 27,784 people – approximately 

3.4 percent of Ventura County’s population. The VCAPCD currently operates 

samplers to collect ambient ozone, continuous PM2.5 and PM10 data. The VCAPCD 

also collects meteorological measurements (wind speed, wind direction, temperature, 

relative humidity, solar radiation, and precipitation) at the station. 

The VCAPCD has operated oxidant and ozone monitors in the Ojai Valley since 

1970. (Oxidant sampling was also conducted in the Ojai Valley for a one year period 

during the mid-1960s.) The VCAPCD also has monitored for particulate matter in the 

Ojai Valley since 1973. 

Ozone 

This station records some of the highest 1-hour and 8-hour ozone averages in 

Ventura County. The station’s annual maximum 1-hour ozone average has been 

reduced from .135 ppm in 1996 to .099 ppm in 2010. In 2010 the station’s 4th highest 

annual maximum 8-hour average was .077 ppm and the maximum 8-hour ozone 

average was .084 ppm. During 2010, ozone averages at the Ojai monitoring station 

exceeded the level of the 8-hour ozone NAAQS on 7 days. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-8 MONITORING DIVISION 

Figure 5 - Ozone Trends Summary: Ojai - Ojai Avenue 

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available in CARB’s AQ Statiatics database for this station from 1996 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect 

PM10

This station has not exceeded the 24-hour PM10 NAAQS. In 2010 the station’s 

annual maximum 24-hour average was 45 μg/m3

. Note that in December 2006 EPA 

revoked the PM10 annual NAAQS. 

Table 21 – Ojai PM10 Maximum 24-Hour Averages 

Annual Maximum 24-Hour Averages 

2007 2008 2009 2010 

99* 61 38 45 

*Flagged as an “Exceptional Event” 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-9 MONITORING DIVISION 

Table 22 – Ojai Station Information 

Station Name > Ojai - Ojai Avenue 

AQS ID 061111004 

Grid Coordinates Latitude: 34o 26’ 53” Longitude: 119o 13’ 53” 

Location At Ventura County Fire Station 21 

Address 1201 Ojai Ave., Ojai CA 93023 

County Ventura County 

Location Type Suburban 

Dist. to road 250 meters 

Traffic count 10,000 vehicles/day 

Groundcover Paved 

PEP audit September 2010 (EPA Contractor) 

Flow audit April 2011 (CARB) 

Representative Area Ojai Valley 

Table 23 – Ojai Monitor Information 

Pollutant > Ozone Non-FEM BAM 

PM2.5

PM10-SSI 

Monitor designation SLAMS N/A SLAMS 

Monitor objective Population 

exposure 

N/A Population 

exposure 

Spatial scale Urban Neighborhood Urban 

Sampling method API Teledyne 400 Met One 1020 

BAM 

Anderson 

SA1200 

Analysis method Ultraviolet 

absorption Beta Attenuation Size Selective Inlet 

Start date 04/01/1996 05/17/2006 04/01/1996 

Operation schedule Continuous Continuous 1-in-6 days 

Sampling season Year-round Year-round Year-round 

Probe height 4.0 meters 4.1 meters 4.1 meters 

Distance from supporting 

structure 1.0 meters 1.5 meters 1.5 meters 

Distance from obstructions 

on roof None None None 

Distance from obstructions 

not on roof None None None 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-10 MONITORING DIVISION 

Pollutant > Ozone Non-FEM BAM 

PM2.5

PM10-SSI 

Distance from trees 10.5 meters 10.5 meters 10.5 meters 

Distance between 

collocated monitors N/A N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material Borosilicate glass 

& FEP Teflon N/A N/A 

Residence time 7.8 seconds N/A N/A 

Will there be changes 

within the next 18 months? No Yes7

 Yes8

Is it suitable for comparison 

against the annual PM2.5? N/A No N/A 

Figure 6 – Map Showing Location Of Ojai – Ojai Avenue 

 

7

 See Section 3.2 

8

 See Section 3.3 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-11 MONITORING DIVISION 

Detailed Station Information 

Piru – Pacific Avenue 

The Piru – Pacific Avenue air monitoring station is located 28 miles from the coast in 

the Santa Clara River Valley, covering 204 square miles and home to 45,107 people 

– approximately 5.5 percent of Ventura County’s population. The VCAPCD currently 

operates samplers to collect ozone and continuous PM2.5 data. The VCAPCD also 

collects meteorological measurements at the station (wind speed, wind direction, 

temperature, relative humidity, solar radiation, and precipitation). 

The VCAPCD has conducted oxidant and ozone sampling in the Santa Clara River 

Valley since 1972. The VCAPCD also has monitored for particulate matter in the 

Santa Clara River Valley since 1973, with limited sampling for a one year period 

during the mid-1960s.

Ozone 

The station’s annual maximum 1-hour ozone average has been reduced from .123 

ppm in 2002 to .087 ppm in 2010. In 2010 the station’s 4th highest maximum 8-hour 

average was .073 ppm and the maximum 8-hour ozone average was .082 ppm. 

During 2010, ozone averages at the Piru monitoring station exceeded the level of the 

8-hour ozone NAAQS on 1 day 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-12 MONITORING DIVISION 

Figure 7 - Ozone Trends Summary: Piru – Pacific Avenue 

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available in CARB’s AQ Statiatics database for this station from 2000 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect 

PM2.5 

This station has not exceeded the 24-hour NAAQS or the annual NAAQS for PM2.5. 

In 2010 the station’s annual 98th percentile 24-hour average was 16.3 μg/m3

 and the 

annual weighted mean was 8.5 μg/m3

. 

Table 24 – Piru – Pacific Avenue PM2.5 Maximum Averages 

Annual 98th Percentile 24-Hour Averages Annual Weighted Means 

2007 2008 2009 2010 2007 2008 2009 2010 

22.3 17.0 18.8 16.3 10.2 9.8 9.5 8.5 

PM10

Monitoring for PM10 at this station was discontinued in July 2004. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-13 MONITORING DIVISION 

Table 25 – Piru Station Information 

Station Name > Piru – Pacific Avenue 

AQS ID 061110009 

Grid Coordinates Latitude: 34o 24’ 16” Longitude: 118o 48’ 36” 

Location On a ranch 

Address 3301 Pacific Ave., Piru CA 93040 

County Ventura County 

Location Type Rural 

Dist. to road 500 meters 

Traffic count 22,000 vehicles/day 

Groundcover Gravel 

PEP audit September 2010 (EPA Contractor) 

Flow audit April 2011 (CARB) 

Representative Area Santa Clara River Valley 

Table 26 – Piru Monitor Information 

Pollutant > Ozone Non-FEM 

BAM PM2.5

FRM PM2.5

Monitor designation SLAMS SLAMS 

Monitor objective High 

concentration N/A Population exposure 

Spatial scale Urban scale N/A Neighborhood 

Sampling method API Teledyne 400 Met One 

1020 BAM 

Partisol-Plus Model 

2025 Sequential Air 

Samplers 

Analysis method Ultraviolet 

absorption 

Beta 

Attenuation Size Selective Inlet 

Start date 11/03/2000 05/26/2006 11/01/2000 

Operation schedule Continuous Continuous 1-in-6 days 

Sampling season Year-round Year-round Year-round 

Probe height 3.8 meters 4.0 meters 4.0 meters 

Distance from 

supporting structure 1.4 meters 1.5 meters 1.5 meters 

Distance from 

obstructions on roof None None None 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-14 MONITORING DIVISION 

Pollutant > Ozone Non-FEM 

BAM PM2.5

FRM PM2.5

Distance from 

obstructions not on 

roof 

None None None 

Distance from trees 28 meters 28 meters 28 meters 

Distance between 

collocated monitors N/A N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material Borosilicate glass 

& FEP Teflon N/A N/A 

Residence time 9.9 seconds N/A N/A 

Will there be changes 

within the next 18 

months? 

No Yes9

 Yes10

Is it suitable for 

comparison against 

the annual PM2.5? 

N/A No Yes 

 

9

 See Section 3.2 

10 See Section 3.2 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-15 MONITORING DIVISION 

Figure 8 – Map Showing Location Of Piru – Pacific Avenue 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-16 MONITORING DIVISION 

Detailed Station Information 

Simi Valley – Cochran Street 

The Simi Valley air monitoring station is located 34 miles from the coast in the Simi 

Valley area, which covers 142 square miles and is home to 162,683 people – 

approximately 19.8 percent of Ventura County’s population. The station covers the 

cities of Simi Valley and Moorpark. The VCAPCD currently operates samplers to 

collect ambient data for ozone, PM10, PM2.5, continuous PM2.5, speciated PM2.5, 

nitrogen dioxide, NMHC, VOC (canisters), and air toxics. 

In addition to sampling for gaseous and particulate air pollutants, the VCAPCD 

collects meteorological measurements (wind speed, wind direction, temperature, 

relative humidity, solar radiation, and visibility) at the station. At the Simi Valley 

Upper Air Station, seven miles to the west, the VCAPCD operates an atmospheric 

profiler, which collects wind and temperature data from 60 meters to 2,000 meters 

above the surface. At the surface, we collect additional meteorological data (wind 

speed, wind direction, temperature, relative humidity, solar radiation, precipitation, 

ultraviolet radiation, and atmospheric pressure). 

The VCAPCD has continuously operated ozone monitors at the same location in 

Simi Valley since 1973. The VCAPCD also has monitored for particulate matter at 

the same location since 1973, and has operated a Type 3 PAMS (Photochemical 

Assessment Monitoring Station) station since 1995. In addition, the station is 

designated a national fine particle speciation trends network site. 

Ozone 

This station typically records the highest 1- and 8-hour ozone levels in Ventura 

County. The Simi Valley air monitoring station’s annual maximum 1-hour ozone 

average has been reduced from .20 ppm in 1989 to .098 ppm in 2010. In 2010 the 

station’s 4th highest annual maximum 8-hour average was .082 ppm and the station’s 

annual maximum 8-hour ozone average was .087 ppm . The station’s 2010 8-hour 

ozone annual design value of .086 ppm is the highest ozone annual design value of 

all monitoring stations in Ventura County. During 2010, ozone averages at the Simi 

Valley monitoring station exceeded the level of the 8-hour ozone NAAQS on 8 days. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-17 MONITORING DIVISION 

Figure 9 - Ozone Trends Summary: Simi Valley-Cochran Street 

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available in CARB’s AQ Statiatics database for this station from 1985 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect. 

PM2.5 

This station has not exceeded the 24-hour NAAQS or the annual NAAQS for PM2.5. 

In 2010 the station’s annual 98th percentile 24-hour average was 17.4 μg/m3

 and the 

annual weighted mean was 8.7 μg/m3

. 

Table 27 – Simi Valley PM2.5 Maximum Averages 

Annual 98th Percentile 24-Hour Averages Annual Weighted Mean 

2007 2008 2009 2010 2007 2008 2009 2010 

31.8 25.7 20.5 17.4 11.7 10.7 10.3 8.7 

PM10

This station has not exceeded the 24-hour PM10 NAAQS. The Simi Valley 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-18 MONITORING DIVISION 

monitoring station has two FRM samplers for PM10. In 2010 the station’s annual 

maximum 24-hour average was 34 μg/m3

. 

Table 28 – Simi Valley PM10 Annual Maximum 24-Hour Averages 

Annual Maximum 24-Hour Average 

2007 2008 2009 2010 

117 80 77 34 

PAMS 

The Simi Valley monitoring station is a Type 3 PAMS site and has operated as such 

since 1994. During the period of July 1 through September 30 of each year the 

VCAPCD operates this site according to established EPA protocols for PAMS 

monitoring and the CAP III protocol. 

40CFR58 Appendix D, Section 5 specifies the network design for the PAMS 

program. Federal regulation require the addition of NOy monitoring at type 3 sites. 

We have not installed the instrumentation due to wide spread questioning by Federal 

and state air agency staff of the rationale of monitoring NOy in Southern California.. 

Additionally, any changes to our existing PAMS network are on hold until EPA 

updates the requirements for the PAMS program.

Table 29 – Simi Valley Station Information 

Station Name > Simi Valley – Cochran Street 

AQS ID 061112002 

Grid Coordinates Latitude: 34o 16’ 34” Longitude: 118o 41’ 1” 

Location On school grounds 

Address 5400 Cochran St., Simi Valley CA 93063 

County Ventura County 

Location Type Suburban 

Dist. to road 140 meters 

Traffic count 10,000 vehicles/day 

Groundcover Asphalt 

PEP audit September 2010 (EPA Contractor) 

Flow audit April 2011 (CARB) 

Representative Area Simi Valley 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-19 MONITORING DIVISION 

Table 30 – Simi Valley Monitor Information 

Pollutant > Ozone Nitrogen Dioxide PM10-SSI 

(Primary) 

Monitor designation PAMS/SLAMS PAMS/SLAMS SLAMS 

Monitor objective High 

concentrations High concentrations High concentrations 

Spatial scale Urban Urban Neighborhood 

Sampling method API Teledyne 400 API 200A Tisch PM10

Analysis method Ultraviolet 

Absorption Chemiluminescent Size Selective Inlet 

Start date 06/01/1985 06/01/1985 11/04/1986 

Operation schedule Continuous Continuous 1-in-6 days 

Sampling season Year-round Year-round Year-round 

Probe height 3.9 meters 3.9 meters 4.8 meters 

Distance from 

supporting structure 1.3 meters 1.3 meters 1.5 meters 

Distance from 

obstructions on roof None None None 

Distance from 

obstructions not on 

roof 

None None None 

Distance from trees 61 meters 61 meters 73 meters 

Distance between 

collocated monitors N/A N/A 3.5 meters 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material Borosilicate glass 

& FEP Teflon 

Borosilicate glass & 

FEP Teflon N/A 

Residence time 7.9 seconds 8.3 seconds N/A 

Will there be changes 

within the next 18 

months? 

No No Yes11

Is it suitable for 

comparison against 

the annual PM2.5? 

N/A N/A N/A 

 

11 See Section 3.2 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-20 MONITORING DIVISION 

Pollutant > PM10-SSI 

(Collocated) FRM PM2.5 Non-FEM BAM PM2.5

Monitor designation SLAMS SLAMS 

Monitor objective High 

concentrations Population exposure N/A 

Spatial scale Neighborhood Neighborhood N/A 

Sampling method Tisch PM10

Partisol-Plus Model 

2025 Sequential Air 

Samplers 

Met One 1020 

BAM 

Analysis method Size Selective 

Inlet Size Selective Inlet Beta Attenuation 

Start date 11/04/1986 01/01/1999 01/01/2004 

Operation schedule 1-in-6 days 1-in-3 days Continuous 

Sampling season Year-round Year-round Year-round 

Probe height 4.8 meters 4.7 meters 4.7 meters 

Distance from 

supporting structure 1.5 meters 1.4 meters 1.4 meters 

Distance from 

obstructions on roof None None None 

Distance from 

obstructions not on 

roof 

None None None 

Distance from trees 73 meters 73 meters 61 meters 

Distance between 

collocated monitors 3.5 meters N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material N/A N/A N/A 

Residence time N/A N/A N/A 

Will there be changes 

within the next 18 

months? 

Yes12 No No 

Is it suitable for 

comparison against 

the annual PM2.5? 

N/A Yes No 

 

12 See Section 3.3 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-21 MONITORING DIVISION 

Pollutant > PM2.5 Speciation VOCs 

Monitor designation Speciation 

Trends 

Speciation 

Trends Type 3 PAMS 

Monitor objective PM2.5

Speciation 

PM2.5

Speciation High concentration 

Spatial scale 

Sampling method Met One 

Super SASS 

URG 3000N 

(carbon 

channel only) 

Xontech 910PC Integrated 

grab sampling 

Analysis method Laboratory gas 

chromatography 

Start date April 1, 2009 

Operation schedule 1-in-3 days 1-in-3 days 

1-in-3 days and days in 

which ozone is predicted to 

exceed .075 ppm 

Sampling season Year-round Year-round July 1 through September 

30 

Probe height 4.7 meters 4.7 meters 5.0 meters 

Distance from 

supporting structure 1.4 meters 1.4 meters 1.5 meters 

Distance from 

obstructions on roof None None None 

Distance from 

obstructions not on 

roof 

None None None 

Distance from trees 73 meters 73 meters 

Distance between 

collocated monitors N/A N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material N/A N/A Borosilicate glass & FEP 

Teflon 

Residence time N/A N/A 

Will there be 

changes within the 

next 18 months? 

No No No 

Is it suitable for 

comparison against 

the annual PM2.5? 

No No N/A 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-22 MONITORING DIVISION 

Figure 10 – Map Showing Location Of Simi Valley – Cochran Street 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-23 MONITORING DIVISION 

Detailed Station Information 

Thousand Oaks – Moorpark Road 

This station is located 21 miles inland in the Conejo Valley, covering 75 square miles 

and home to 150,025 people – approximately 17.5 percent of Ventura County’s 

population. The VCAPCD currently operates samplers to collect ambient ozone and 

continuous PM2.5 data. The VCAPCD also collects meteorological measurements at 

the station (wind speed, wind direction, temperature, relative humidity, solar radiation, 

and precipitation). 

The VCAPCD has conducted ozone sampling in the Conejo Valley since 1973. The 

VCAPCD also has monitored for particulate matter in the Conejo Valley since 1979, 

with limited sampling prior to that. 

Ozone 

The Thousand Oaks monitoring station’s annual maximum 1-hour ozone average 

has been reduced from .148 ppm in 1995 to .104 ppm in 2010. In 2010 the station’s 

4th highest annual maximum 8-hour average was .076 ppm and the annual maximum 

8-hour ozone average was .091 ppm. During 2010, ozone averages at the 

Thousand Oaks monitoring station exceeded the level of the 8-hour NAAQS on six 

days. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-24 MONITORING DIVISION 

Figure 11 - Ozone Trends Summary: Thousand Oaks-Moorpark Road

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available in CARB’s AQ Statiatics database for this station from 1992 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect. 

PM2.5 

This station has not exceeded the 24-hour NAAQS or the annual NAAQS for PM2.5. 

The Thousand Oaks monitoring station has two federal reference monitors for PM2.5. 

In 2010 the station’s 98th percentile annual maximum 24-hour average was 21.3 

μg/m3

 and the annual weighted mean was 8.7 μg/m3. 

Table 31 – Thousand Oaks PM2.5 Maximum Averages 

Annual 98th Percentile 24-Hour Averages Annual Weighted Means 

2007 2008 2009 2010 2007 2008 2009 2010 

24.9 20.7 21.1 21.3 10.5 10.3 10.7 8.7 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-25 MONITORING DIVISION 

PM10

Monitoring for PM10 at this station was discontinued in July 2004. 

Table 32 – Thousand Oaks Station Information 

Station Name > Thousand Oaks – Moorpark Road 

AQS ID 061110007 

Grid Coordinates Latitude: 34o 12’ 37” Longitude: 118o 52’ 14” 

Location On school grounds 

Address 2323 Moorpark Rd., Thousand Oaks CA 91360 

County Ventura County 

Location Type Suburban 

Dist. to road 175 meters 

Traffic count 7,000 vehicles/day 

Groundcover Asphalt 

PEP audit September 2010 (EPA Contractor) 

Flow audit April 2011 (CARB) 

Representative Area Conejo Valley 

Table 33 – Thousand Oaks Monitor Information 

Pollutant > Ozone Non-FEM 

BAM PM2.5

FRM PM2.5 (Primary) 

Monitor designation SLAMS SLAMS 

Monitor objective Population 

exposure N/A Population exposure 

Spatial scale Urban N/A Neighborhood 

Sampling method API Teledyne 

400 

Met One 

1020 BAM 

Partisol-Plus Model 

2025 Sequential Air 

Samplers 

Analysis method Ultraviolet 

Absorption 

Beta 

Attenuation Size Selective Inlet 

Start date 03/01/1992 May 2007 01/01/1999 

Operation schedule Continuous Continuous 1-in-6 days 

Sampling season Year-round Year-round Year-round 

Probe height 5.0 meters 3.0 meters 5.0 meters 

Distance from 

supporting structure 1.5 meters 1.0 meters 1.5 meters 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-26 MONITORING DIVISION 

Pollutant > Ozone Non-FEM 

BAM PM2.5

FRM PM2.5 (Primary) 

Distance from 

obstructions on roof None None None 

Distance from 

obstructions not on 

roof 

None None None 

Distance from trees N/A N/A N/A 

Distance between 

collocated monitors N/A N/A 2.0 meters 

Unrestricted airflow 360 degrees 360 degrees 360 degrees 

Probe material 

Borosilicate 

glass & FEP 

Teflon 

N/A N/A 

Residence time 13.1 seconds N/A N/A 

Will there be changes 

within the next 18 

months? 

No Yes13 Yes14

Is it suitable for 

comparison against the 

annual PM2.5? 

N/A No Yes 

Pollutant > FRM PM2.5 (Collocated) 

Monitor designation SLAMS 

Monitor objective Population exposure 

Spatial scale Neighborhood 

Sampling method Partisol-Plus Model 2025 Sequential Air 

Samplers 

Analysis method Size Selective Inlet 

Start date 01/01/1999 

Operation schedule 1-in-6 days 

Sampling season Year-round 

Probe height 5.0 meters 

Distance from supporting structure 1.5 meters 

Distance from obstructions on roof None 

Distance from obstructions not on roof None 

Distance from trees N/A 

 

13 See Section 3.3 14 See Section 3.3 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-27 MONITORING DIVISION 

Pollutant > FRM PM2.5 (Collocated) 

Distance between collocated monitors 2.0 meters 

Unrestricted airflow 360 degrees 

Probe material N/A 

Residence time N/A 

Will there be changes within the next 18 

months? No 

Is it suitable for comparison against the 

annual PM2.5? Yes 

Figure 12 – Map Showing Location Of Thousand Oaks – Moorpark Road 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-28 MONITORING DIVISION 

Detailed Station Information 

Ventura - Emma Wood State Beach 

Due to the ongoing costs of operating the Ventura station and due to siting issues the 

Ventura station discontinued monitoring on April 28, 2011 

The Ventura monitoring station was located along the coast at Emma Wood State 

Beach, and represented a coastal area covering 119 square miles and home to 

234,275 people – approximately 28 percent of Ventura County’s population. The 

VCAPCD operated samplers to collect ambient data for ozone, and VOC (canisters). 

The VCAPCD also collected meteorological measurements (wind speed, wind 

direction, temperature, relative humidity, and solar radiation). 

The VCAPCD has conducted oxidant and ozone sampling in the coastal area since 

1972 at locations ranging from Point Mugu to La Conchita. Most of the monitoring, 

however, has occurred at stations in the Ventura area. In addition, limited sampling 

for oxidants was conducted in the area during the mid- and late-1960s and early 

1970s. The VCAPCD has conducted ozone sampling at the Ventura - Emma Wood 

station since 1984. This station has also operated as a Type 1 PAMS site since 

1996. 

Ozone 

Typically, Ventura - Emma Wood monitoring station recorded the lowest to second 

lowest 1-hour and 8-hour ozone averages in Ventura County. The station’s 

maximum 1-hour ozone average has been reduced from .23 ppm in 1989 to .098 

ppm in 2010, the station’s 4th highest annual maximum 8-hour average was .060 

ppm and the maximum 8-hour ozone average was .069 ppm. The Ventura - Emma 

Wood monitoring station did not exceed the level of the 8-hour ozone NAAQS in 

2010. 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-29 MONITORING DIVISION 

Figure 13 - Ozone Trends Summary: Ventura-Emma Wood State Beach 

NOTES: 

1. Area: Ventura County; South Central Coast Air Basin; Ventura 8-Hour Ozone Planning Area 

2. District: Ventura County APCD 

3. Years: Ozone data are available CARB’s AQ Statiatics database for this station from 1984 through 2009. 

4. All concentrations expressed in parts per million. 

5. An exceedance is not necessarily a violation. 

6. The 1-hour ozone NAAQS was revoked in June 2005 and is no longer in effect 

PAMS 

The Ventura - Emma Wood monitoring station was a Type 1 PAMS site and was 

operated as such since 1996. During the period of July 1 through September 30 of 

each year the VCAPCD operated this site according to established EPA protocols for 

PAMS monitoring and the CAP III protocol. See Section 3.3 for a discussion of 

changes to the PAMS monitoring program at this station. 

Table 34 – Ventura Station Information 

Station Name > Ventura - Emma Wood State Beach 

AQS ID 061112003 

Grid Coordinates Latitude: 34o 16’ 50” Longitude: 119o 18’ 55” 

Location State Park 

Address Emma Wood State Beach, Ventura CA 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-30 MONITORING DIVISION 

Station Name > Ventura - Emma Wood State Beach 

County Ventura County 

Location Type Suburban 

Dist. to road 50 meters 

Traffic count 175,000 vehicles/day 

Groundcover Grass and vegetation 

PEP audit N/A 

Flow audit N/A 

Representative Area Ventura Coastal 

Table 35 – Ventura Monitor Information 

Pollutant > Ozone VOCs 

Monitor designation PAMS/SLAMS Type 1 PAMS 

Monitor objective General/Background 

Spatial scale Neighborhood 

Sampling method API/Teledyne 400 Xontech 910A/912 Integrated 

grab sampling 

Analysis method Ultraviolet Absorption Laboratory gas chromatography 

Start date 03/01/1984 199615

Operation schedule Continuous 

1-in-3 days and days in which 

ozone is predicted to exceed 

.075 ppm 

Sampling season Year-round July 1 through September 30 

Probe height 4.0 meters 4.0 meters 

Distance from 

supporting structure 1.0 meters 1.0 meters 

Distance from 

obstructions on roof None None 

Distance from 

obstructions not on roof None None 

Distance from trees N/A N/A 

Distance between 

collocated monitors N/A N/A 

Unrestricted airflow 360 degrees 360 degrees 

Probe material Borosilicate glass & 

FEP Teflon Borosilicate glass & FEP Teflon 

 

15 The last samples collected at Ventura-Emma Wood State Beach was in 2005 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-31 MONITORING DIVISION 

Pollutant > Ozone VOCs 

Residence time 10.5 seconds 

Will there be changes 

within the next 18 

months? 

N/A N/A 

Figure 14 – Map Showing Location of Ventura – Emma Wood State Beach 
2011 AMBIENT AIR MONITORING NETWORK PLAN 

VENTURA COUNTY APCD A-32 MONITORING DIVISION 

Detailed Station Information 

Simi Valley – Upper Air 

Table 36 – Simi Valley – Upper Air Station Information 

Station Name > Simi Valley – Upper Air 

AQS ID 061110008 

Grid Coordinates Latitude: 34o 17’ 28” Longitude: 118o 47’ 51” 

Location At Simi Valley Landfill 

Address 2801 Madera Rd., Simi Valley CA 93063 

County Ventura County 

Figure 15 – Map Showing Location Of Simi Valley – Upper Air