UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 WASHINGTON D.C. 20460

OFFICE OF THE ADMINISTRATOR

SCIENCE ADVISORY BOARD

September 28, 2011

EPA-CASAC-11-010

The Honorable Lisa P. Jackson

Administrator 

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW 

Washington, DC 20460 

Subject: Review of EPA's Photochemical Assessment Monitoring Stations (PAMS) Network 

Re-engineering Project

Dear Administrator Jackson: 

The Clean Air Scientific Advisory Committee (CASAC) Air Monitoring and Methods Subcommittee 

(AMMS) held three public teleconference calls on May 16, May 17, and July 18, 2011 to review EPA's 

Photochemical Assessment Monitoring Stations (PAMS) Network Re-engineering project. The 

chartered CASAC reviewed the AMMS PAMS Review Report during the August 29, 2011 public 

teleconference, and approved the Report after the teleconference. EPA’s Office of Air Quality Planning 

and Standards requested the CASAC AMMS Subcommittee to review its White Paper entitled “White 

Paper on EPA’s PAMS Network Re-engineering project” (April 2011), respond to charge questions, and 

provide advice and ideas on how to improve the PAMS program. This letter provides CASAC’s 

response to this advisory request and summarizes CASAC’s views on monitoring issues pertaining to 

EPA's PAMS Network Re-engineering project. The CASAC and Panel membership is listed in 

Enclosure A. CASAC’s responses to EPA’s charge questions are presented in Enclosure B. References 

that support the response to Charge Question 17 are provided in Enclosure C. Finally, Enclosure D is a 

compilation of individual panel member comments.

The 1990 Clean Air Act (CAA) Amendments required that EPA revise ambient air quality surveillance 

regulations to include provisions for enhanced monitoring of ozone (O3), oxides of nitrogen (NOx), 

volatile organic compounds (VOCs), selected carbonyl compounds, and meteorological parameters.

Under the CAA, states were required to adopt and implement a program to improve ambient monitoring 

activities and the monitoring of emissions of NOx and VOC. Each State Implementation Plan (SIP) for 

the affected areas must contain measures to implement the ambient monitoring of such air pollutants.

EPA subsequently required states to establish PAMS as part of their SIP monitoring networks in ozone 

nonattainment areas classified as serious, severe, or extreme. In 2006, EPA revised the PAMS 

requirements to allow PAMS monitoring to be more customized to local data needs, and to provide 

states with flexibility to reduce the overall size of their PAMS programs and to use the associated 

resources for other types of monitoring they consider more useful. The chief objective of the PAMS 
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requirements is to provide an air quality database that will assist air pollution control agencies in 

evaluating, tracking the progress of, and, if necessary, refining control strategies for attaining the ozone 

National Ambient Air Quality Standards (NAAQS). In addition, data from the PAMS will aid in 

preparation of air quality trends, assist in evaluating photochemical model performance, and help states 

implement the most cost-effective regulatory controls. 

In its White Paper, EPA identified several issues associated with the current PAMS Network Design, 

including poor spatial coverage (with PAMS sites mostly in coastal areas), limited value for model 

development/testing, limited seasonal monitoring of PAMS, and limited network design for assessing 

extremes in variables associated with PAMS monitoring. EPA identified various options to address these 

issues, including lengthening the PAMS monitoring season, providing for mobile PAMS sites, and 

adding PAMS measurements to the existing urban “NCore” multi-pollutant network that integrates 

several advanced measurement systems for particles, pollutant gases and meteorology.

Overall, CASAC concludes that EPA’s proposed approaches for monitoring methods and network 

design pertaining to EPA's PAMS Network Re-engineering project are appropriate, and that the network

will continue to assist in developing a better understanding of ozone chemistry, transport, modeling, and 

attainment demonstration. CASAC provides the following priority recommendations to strengthen and 

improve the PAMS program. Additional details on these and other recommendations are discussed 

within the enclosed report.

First, EPA should revise PAMS network objectives to reflect a balanced approach that would enable 

state and local agencies to more effectively support their local attainment efforts and allow EPA to 

continue to evaluate national trends of ozone precursors. CASAC finds that the existing uniform 

national network design model for PAMS is outdated and too resource intensive, and recommends that 

greater flexibility for network design and implementation of the PAMs program be transferred to state 

and local monitoring agencies to allow monitoring, research and data analysis to be better tailored to the 

specific needs of each ozone problem area. The PAMS monitoring season should not be mandated and 

rigid; it should be flexible, adopted on a region-by-region basis, and based on rational guidance utilizing 

location specific ozone observations. This flexibility should not conflict with national goals for the 

PAMS program.

Second, PAMS data analysis at the national and regional levels should focus on trending, accountability 

analyses for emission reduction programs, and evaluation of air quality models. Trending must be 

carefully conducted given the range of objectives that are used to site monitors. For example, 

accountability analyses on the ozone precursors profile, ozone itself, and on other pollutants should 

examine the impact of increased ethanol use in motor vehicle fuels. As data analyses are carried out, 

there should be interaction with data users to assure that the analyses will address issues associated with 

air quality modeling. CASAC also recommends that PAMS data be used to conduct national or regional 

analyses to investigate ozone formation potential. Such analyses should support model development for 

secondary organic aerosol formation. Furthermore, since the lack of easy access to PAMS data is often 

cited as a major obstacle to its use, CASAC strongly recommends that PAMS data be made available 

through a user-friendly portal to promote more widespread use. Also, in the re-design of the overall 

PAMS network, EPA should break away from the 1990’s instrumentation and sampling methods and 

consider newer, less expensive and more suitable monitoring packages.
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Third, EPA should reduce the minimum national requirements for reporting of specific organic species 

under the PAMS network, and provide various criteria for such reporting. CASAC recommends that 

EPA should add more biogenic VOC species to the required species monitoring list given the current 

trends of lower anthropogenic VOCs and the implications for rural areas. In addition, CASAC 

recommends adding additional compounds that may help track emissions from additional non-mobile 

sources or more recent fuel formulations from mobile sources.

In closing, CASAC appreciates the opportunity to provide input to EPA at this stage in the process, and 

trusts that our comments will be useful to EPA as it revises the PAMS program. We look forward to 

receiving the Agency’s response.

Sincerely,

/Signed/ /Signed/

Mr. George A. Allen, Chair

CASAC Air Monitoring and Methods 

Subcommittee 

Enclosures

Dr. Jonathan M. Samet, Chair

Clean Air Scientific Advisory Committee
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NOTICE

This report has been written as part of the activities of the EPA's Clean Air Scientific Advisory 

Committee (CASAC), a federal advisory committee independently chartered to provide extramural 

scientific information and advice to the Administrator and other officials of the EPA. CASAC provides 

balanced, expert assessment of scientific matters related to issues and problems facing the Agency. This 

report has not been reviewed for approval by the Agency and, hence, the contents of this report do not 

necessarily represent the views and policies of the EPA, nor of other agencies within the Executive 

Branch of the federal government. In addition, any mention of trade names or commercial products does 

not constitute a recommendation for use. CASAC reports are posted on the EPA Web site at: 

http://www.epa.gov/casac.
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Enclosure A – Roster

U.S. Environmental Protection Agency

Clean Air Scientific Advisory Committee

CASAC Air Monitoring and Methods Subcommittee (AMMS)

CHAIR

Mr. George A. Allen, Senior Scientist, Northeast States for Coordinated Air Use Management 

(NESCAUM), Boston, MA

MEMBERS

Dr. David T. Allen, Professor, Department of Chemical Engineering, University of Texas, Austin, TX

Dr. Linda Bonanno, Research Scientist, Office of Science/Division of Air Quality, New Jersey 

Department of Environmental Protection, Trenton, NJ 

Dr. Doug Burns, Research Hydrologist, U.S. Geological Survey 

Dr. Judith Chow, Research Professor, Desert Research Institute, Air Resources Laboratory, University 

of Nevada, Reno, NV

Dr. Kenneth Demerjian, Professor and Director, Atmospheric Sciences Research Center, State 

University of New York, Albany, NY

Dr. Eric Edgerton, President, Atmospheric Research & Analysis, Inc., Cary, NC

Mr. Henry (Dirk) Felton, Research Scientist, Division of Air Resources, Bureau of Air Quality 

Surveillance, New York State Department of Environmental Conservation, Albany, NY

Dr. Philip Fine, Atmospheric Measurements Manager, South Coast Air Quality Management District, 

Diamond Bar, CA

Dr. Philip Hopke, Bayard D. Clarkson Distinguished Professor, Department of Chemical and 

Biomolecular Engineering, Clarkson University, Potsdam, NY

Dr. Rudolf Husar, Professor, Mechanical Engineering, Engineering and Applied Science, Washington 

University, St. Louis, MO
iii

Dr. Daniel Jacob, Professor, Atmospheric Sciences, School of Engineering and Applied Sciences, 

Harvard University, Cambridge, MA

Dr. Peter H. McMurry, Professor, Department of Mechanical Engineering, University of Minnesota, 

Minneapolis, MN

Dr. Allen Robinson, Professor, Department of Engineering and Public Policy, Carnegie Mellon 

University, Pittsburgh, PA

Dr. Armistead (Ted) Russell, Professor, Department of Civil and Environmental Engineering, Georgia 

Institute of Technology, Atlanta, GA

Dr. James Jay Schauer, Professor, Department of Civil and Environmental Engineering, College of 

Engineering, University of Wisconsin - Madison, Madison, WI

Dr. Jay Turner, Associate Professor, Environmental & Chemical Engineering, Campus Box 1180, 

Washington University, St Louis, MO

Dr. Yousheng Zeng, Managing Partner, Providence Engineering & Environmental Group LLC, Baton 

Rouge, LA

SCIENCE ADVISORY BOARD STAFF

Mr. Edward Hanlon, Designated Federal Officer, U.S. Environmental Protection Agency, Science 

Advisory Board Staff, Washington, DC
iv

U.S. Environmental Protection Agency 

Clean Air Scientific Advisory Committee (CASAC) 

CHAIR 

Dr. Jonathan M. Samet, Professor and Flora L. Thornton Chair, Department of Preventive Medicine, 

University of Southern California, Los Angeles, CA 

MEMBERS 

Mr. George A. Allen, Senior Scientist, Northeast States for Coordinated Air Use Management 

(NESCAUM), Boston, MA 

Dr. Joseph D. Brain, Cecil K. and Philip Drinker Professor of Environmental Physiology, Department 

of Environmental Health, Harvard School of Public Health, Harvard University, Boston, MA 

Dr. H. Christopher Frey, Professor, Department of Civil, Construction and Environmental 

Engineering, College of Engineering, North Carolina State University, Raleigh, NC 

Dr. Armistead (Ted) Russell, Professor, Department of Civil and Environmental Engineering, Georgia 

Institute of Technology, Atlanta, GA 

Dr. Helen Suh, Senior Lecturer on Environmental Chemistry and Exposure Assessment, Department of 

Environmental Health, School of Public Health, Harvard University, Boston, MA 

Dr. Kathleen Weathers, Senior Scientist, Cary Institute of Ecosystem Studies, Millbrook, NY 

SCIENCE ADVISORY BOARD STAFF 

Dr. Holly Stallworth, Designated Federal Officer, U.S. Environmental Protection Agency, Washington, 

DC 
v

Abbreviations and Acronyms 

ACARS Aircraft Communications Addressing and Reporting System 

AMDAR Aircraft Meteorological Data Relay 

AMMS Air Monitoring and Methods Subcommittee 

AOD Aerosol Optical Depth 

CAA Clean Air Act 

CASAC Clean Air Scientific Advisory Committee

CMAQ Community Multiscale Air Quality Model

CRD Cavity Ringdown

CO Carbon Monoxide

DOAS Differential Optical Absorption Spectroscopy

EPA U.S. Environmental Protection Agency

FID Flame Ionization Detector

GC Gas Chromatograph

LOD Limit of Detection

MS Mass Spectrometer

NAAQS National Ambient Air Quality Standards 

NATTS National Air Toxics Trends Sites

NEI National Emission Inventory

NOAA National Oceanic and Atmospheric Administration 

NOx Oxides of Nitrogen 

OAQPS EPA Office of Air Quality Planning and Standards

ORD EPA Office of Research and Development

O3 Ozone 

PAMS Photochemical Assessment Monitoring Stations

PM Particulate Matter

QA/QC Quality Assurance/Quality Control 

RPO Regional Planning Organization 

SAB EPA Science Advisory Board

SIP State Implementation Plan

SOA Secondary Organic Aerosol 

SOx Sulfur Oxides 

TNMH Total Non-Methane Hydrocarbon

VOCs Volatile Organic Compounds 
1

Enclosure B

CASAC Air Monitoring and Methods Subcommittee (AMMS)

Consensus Responses to Charge Questions

Background:

Section 182 (c)(1) of the 1990 Clean Air Act (CAA) Amendments required the EPA to promulgate rules 

for enhanced monitoring to obtain more comprehensive and representative data on ozone air pollution:

“In order to obtain more comprehensive and representative data on ozone air pollution, not 

later than 18 months after November 15, 1990, the Administrator shall promulgate rules, after 

notice and public comment, for enhanced monitoring of ozone, oxides of nitrogen, and volatile 

organic compounds. The rules shall, among other things, cover the location and maintenance of 

monitors. ...”

Section 185(b) of the CAA required EPA to work with the National Academy of Sciences (NAS) to 

conduct a study on the role of ozone precursors in tropospheric ozone formation and control.

“The Administrator, in conjunction with the National Academy of Sciences, shall conduct a study 

on the role of ozone precursors in tropospheric ozone formation and control. The study shall 

examine the roles of NOx and VOC emission reductions, the extent to which NOx reductions may 

contribute (or be counterproductive) to achievement of attainment in different nonattainment 

areas, the sensitivity of ozone to the control of NOx, the availability and extent of controls for 

NOx, the role of biogenic VOC emissions, and the basic information required for air quality 

models.”

In 1992, the NAS finalized the report entitled “Rethinking the Ozone Problem in Urban and Regional 

Air Pollution” (National Academy of Sciences, 1992). The report found that “Ambient air quality 

measurements now being performed are inadequate to elucidate the chemistry of atmospheric VOCs or 

to assess the contributions of different sources to individual concentrations of these compounds.” which 

made several recommendations for improving monitoring for precursors of ozone:

“New measurement strategies that incorporate more accurate and precise measurements of the 

individual trace compounds involved in ozone chemistry should be developed to advance 

understanding of the formation of high concentrations of ozone in the United States and to verify 

estimates of VOC and NOx emissions.”

In response to these requirements and the recommendations of the NAS report, on February 12, 1993, 

EPA revised the ambient air quality surveillance regulations in Title 40 Part 58 of the Code of Federal 

Regulations (40 CFR Part 58) to include provisions for enhanced monitoring of ozone (O3), oxides of 

nitrogen (NOx), volatile organic compounds (VOCs), selected carbonyl compounds, and meteorological 

parameters. The revisions required states and local monitoring agencies (“monitoring agencies”) to 

establish Photochemical Assessment Monitoring Stations (PAMS) in ozone nonattainment areas 

classified as serious, severe, or extreme. The chief objective of the enhanced ozone monitoring revisions 

is to provide an air quality database that will assist air pollution control agencies in evaluating, tracking 

the progress of, and, if necessary, refining control strategies for attaining the ozone National Ambient 

Air Quality Standards (NAAQS). Ambient concentrations of ozone and ozone precursors will be used to 

make attainment/nonattainment decisions, aid in tracking VOC and NOx emission inventory reductions, 
2

better characterize the nature and extent of the ozone problem, and prepare air quality trends. In 

addition, data from the PAMS provide an improved database for evaluating photochemical model 

performance, especially for future control strategy mid-course corrections as part of the continuing air 

quality management process. The data will be particularly useful to states in ensuring the 

implementation of the most cost-effective regulatory controls.

Twenty two areas were identified as being subject to PAMS at the time the rules were promulgated.

Since then the number of areas subject to PAMS has grown to 25. Each PAMS area was required to 

install between 2 and 5 PAMS sites depending on the population of the area.1

• The number of required PAMS sites was reduced; only one Type 2 site is required per area 

regardless of population, Type 4 sites are not required, and only one Type 1 or one Type 3 

site is required per area. 

Four types of PAMS sites 

were identified: a) upwind (Type 1); b) maximum precursor emission rate (Type 2); c) maximum ozone 

(Type 3); and d) extreme downwind (Type 4) sites. The number and type of sites required was 

contingent on the population of the PAMS area.

In 2006, the PAMS requirements were revised to lower the minimum requirements for PAMS. The 

following changes were made to the PAMS requirements:

• The requirements for speciated VOC measurements were reduced. Speciated VOC 

measurements are only required at Type 2 sites and one other site (either Type 1 or Type 3) 

per PAMS area. Carbonyl sampling is only required in areas classified as serious or above for 

the 8-hour O3 standard.

• Conventional NO2/ NOx monitors are only required at Type 2 sites. 

• High sensitivity NOy monitors are required at one site per PAMS area (either Type 1 or Type 

3). 

• High sensitivity carbon monoxide (CO) monitors are required at Type 2 sites.

The intent of these revisions were to “allow PAMS monitoring to be more customized to local data 

needs rather than meeting so many specific requirements common to all subject O3 nonattainment areas; 

the PAMS changes would also give states the flexibility to reduce the overall size of their PAMS 

programs—within limits—and to use the associated resources for other types of monitoring they 

consider more useful” (71 FR 2714).

EPA’s Office of Air Quality Planning and Standards (OAQPS) sought CASAC advice and ideas on how 

EPA can improve the PAMS program. CASAC focused on the following charge questions as part of its 

review, and provides the following responses to these charge questions.

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated?

As noted in EPA’s Technical Assistance Document for Sampling and Analysis of Ozone Precursors

(USEPA, 1998), the current PAMS objectives are: 

• Provide a speciated ambient air database which is both representative and useful for 

ascertaining ambient profiles and distinguishing among various individual VOC. These data 

 1 Flexibility was allowed such that some sites were able to serve as more than one PAMS area. For example a site could 

serve as an extreme downwind site (Type 4) for one area and an upwind site (Type 1) for another.
3

can later be used as evaluation tools for control strategies, cost-effectiveness, and for 

understanding the mechanisms of pollutant transport.

• Provide local, current meteorological and ambient data to serve as initial and boundary 

condition information for photochemical grid models. These data can later be used as a 

baseline for model evaluation and to minimize model adjustments and reliance on default 

settings.

• Provide a representative, speciated ambient air database which is characteristic of source 

emission impacts. These data can be particularly useful in analyzing emissions inventory 

issues and corroborating progress toward attainment.

• Provide ambient data measurements which would allow later preparation of unadjusted and 

adjusted pollutant trends reports.

• Provide additional measurements of selected criteria pollutants. Such measurements can later 

be used for attainment/nonattainment decisions and to construct NAAQS maintenance plans.

• Provide additional measurements of selected criteria and non-criteria pollutants from 

properly-sited locations. Such measurements can later be used for evaluating population 

exposure to air toxics as well as criteria pollutants.

In general, all of these objectives for the network remain valid and important, and will continue to assist 

in developing a better understanding of ozone chemistry, transport, modeling, and attainment 

demonstration. Additional objectives are emerging, including characterizing precursors of secondary 

organic aerosols, and characterizing long range transport of pollutants.

CASAC suggests that the objectives could be expressed in more concise language, and that objectives 

may need to be revised to include both a national and regional focus because national objectives may be 

different from regional objectives.

In prioritizing objectives for the network, CASAC notes that the network has been addressing some of 

these objectives (such as establishing baselines for VOC concentrations) for more than 15 years. In 

contrast, some objectives require the collection of new data. For example, changes in the composition of 

fuel and exhaust emissions as fuels evolve under Renewable Fuel Standards will require the collection 

of new datasets over the next decade. In addition, CASAC recommends that prioritization of objectives 

be region or air shed specific. Different non-attainment areas will have different outstanding questions to 

be answered, whether it is more VOC data and trends, or inventory uncertainties, or background 

conditions, or upper air meteorology. Prioritizing objectives should include both national and regional 

objectives.

Regarding the role of PAMS in terms of air toxics and climate relevant gases, EPA should consider 

these as secondary objectives. 

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

CASAC concludes that EPA should consider the following additional objectives for the PAMS program:

1) Provide compound-specific diurnal patterns to evaluate emission profiles (as specified in emissions 

models by source) and for evaluation of the air quality modeling system overall (e.g., see Doraiswamy et 

al., 2009; Ren et al., 2003; and Ren et al., 2006). 
4

2) Measurement of secondary organic aerosol (SOA) precursors with an emphasis on gathering data to 

support development of effective strategies for the reduction of SOA.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of required 

sites? 

The current PAMS network design calls for an array of sites around each PAMS area. Four different 

types of PAMS sites are identified in the current network design:

• Type 1 Sites: Upwind and background characterization site. These sites are established to 

characterize upwind background and transported ozone and its precursor concentrations 

entering the area and will identify those areas which are subjected to overwhelming incoming 

transport of ozone. The #1 sites are located in the predominant morning upwind direction 

from the local area of maximum precursor emissions and at a distance sufficient to obtain 

urban scale2

• Type 2 Sites: Maximum ozone precursor emissions impact site. These sites are established to 

monitor the magnitude and type of precursor emissions in the area where maximum 

precursor emissions representative of the MSA/CMSA are expected to impact and are suited 

for the monitoring of urban air toxic pollutants. The #2 Sites are located immediately 

downwind (using the same morning wind direction as for locating Site #1) of the area of 

maximum precursor emissions and are typically placed near the downwind boundary of the 

central business district (CBD) or primary area of precursor emissions mix to obtain 

neighborhood scale measurements. Additionally, a second #2 Site may be required 

depending on the size of the area.

measurements. 

• Type 3 Sites: Maximum ozone concentration site. These sites are intended to monitor 

maximum ozone concentrations occurring downwind from the area of maximum precursor 

emissions. Locations for #3 Sites should be chosen so that urban scale measurements are 

obtained. Typically, these sites are located 10 to 30 miles from the fringe of the urban area.

• Type 4 Sites: Extreme downwind monitoring site. These sites are established to characterize 

the extreme downwind transported ozone and its precursor concentrations exiting the area 

and will identify those areas which are potentially contributing to overwhelming ozone 

transport into other areas. The #4 Sites are located in the predominant afternoon downwind 

direction from the local area of maximum precursor emissions at a distance sufficient to 

obtain urban scale measurements.

The PAMS network was designed to capture upwind, urban core and downwind concentrations of ozone 

and ozone precursors and to use these data to support control strategy development and atmospheric 

modeling, with respect to the 1-hour ozone standard. However, given the current 8-hour standard with 

potentially very different (broader) areas of non-attainment than with the 1-hour standard, CASAC 

concludes that EPA should reassess and perhaps redefine the current meaning of upwind and downwind.

 2 Urban scale defines concentrations within an area of city-like dimensions, on the order of 4 to 50 kilometers. Within a city, 

the geographic placement of sources may result in there being no single site that can be said to represent air quality on an 

urban scale. Neighborhood scale defines concentrations within some extended area of the city that has relatively uniform 

land use with dimensions in the 0.5 to 4.0 kilometers range. The neighborhood and urban scales have the potential to overlap 

in applications that concern secondarily formed or homogeneously distributed air pollutants.
5

CASAC concludes that temporal changes in the character and intensity of precursor emissions need to 

be captured by the network. In some Type 1 areas, the currently placed upwind ozone monitors are or 

could become non-attainment, depending on the level of the NAAQS. Long-range and medium-range 

transport are likely to be more important in the context of an 8-hour standard than a 1-hour standard. At 

the same time, the mix of VOC emissions is changing due to changes in fuel composition, among other 

factors, and NOx emissions are declining, due to control of stationary and mobile sources.

The process of locating PAMS sites should seek to minimize redundancy, but provide robust 

information for defining ozone gradients and fluxes. Network design should rely on a combination of 

observations and model projections to define ozone production regions and modes of transport.

Flexibility on the number and types of sites should still be available to the local and regional air quality 

agencies to meet their specific needs.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

CASAC concludes that EPA should consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage. EPA could require 

such measurements to better characterize regional-scale ozone problems.

Since PAMS requirements originated, long-range transport of ozone has been recognized as more 

important than previously considered. Thus, there is a need to establish boundary conditions for the 

models and to provide tests for biogenic VOC emissions models. In addition, there are now areas in both 

the eastern and western US where natural gas development is rapidly expanding. These areas are sources 

of NOx and VOC that contribute to downwind ozone concentrations. CASAC requests that EPA 

consider adding PAMS measurements to a set of sites that are part of existing air monitoring networks.

This addition might involve only a slight change to current measurements at these sites, and could 

therefore be done at minimal cost.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone 

sites in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, 

all urban NCore sites)?

CASAC recommends extending the existing PAMS network by adding regional PAMS monitoring sites.

This would improve spatial characterization, identify undocumented sources and contribute to better 

understanding of ozone precursor chemistry. Regional PAMS sites should be located at existing regional 

ozone sites with due consideration of NCORE and other infrastructures. The site selection criteria 

should be flexible and adapted to the needs of each region. It is understood that given the limited 

resources, the regional PAMS sites would be added at the expense of some of the current urban sites. At 

regional sites, the sampling methods can be simpler than the urban PAMS sites.

In the re-design of the overall PAMS network, EPA should break away from the 1990’s instrumentation 

and sampling methods and consider newer, less expensive and more suitable monitoring packages.
6

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

CASAC concludes that mobile or temporary sites can provide useful measurement approaches for 

targeted purposes. Although mobile and temporary sites can be very useful, CASAC does not 

recommend that EPA make them mandatory across the country. They should be deployed at the 

discretion of state and local monitoring agencies based on specific local needs. Temporary sites can be 

constructed on a transportable platform (e.g., a trailer that can be moved from one location to another).

A transportable monitoring platform can be deployed to a location for a period of time (e.g., a week to a 

year depending on the purpose of the deployment) during which some or all PAMS parameters can be 

monitored. Although this type of temporary site does not provide data for trending over a long period of 

time, it may provide a good indication on levels of ozone and its precursors. Deployment at a location 

for a month or multiple months would be most useful. Unless the purpose of monitoring is for long-term 

trending or NAAQS compliance determination, the information that can be extracted from any 

monitoring site gradually diminishes as the monitoring period is extended. By utilizing mobile or 

temporary sites, a monitoring agency can explore more locations and therefore achieve a better 

understanding about the spatial distribution of ozone and its precursors. Compared to fixed monitoring 

sites, mobile or temporary sites provide the needed flexibility and enable monitoring agencies to strike a 

balance between the temporal and spatial domains in the budget constrained environment.

Flexibility is desired because it will allow monitoring, research and data analysis to be tailored to the 

specific needs of each ozone problem area. Flexible approaches will also likely provide the information 

needed to select regionally specific workable control strategies, and meet the broad needs of diverse 

groups of stakeholders who use PAMS data.

Mobile and temporary sites could replace some Type 2 sites (i.e., source-oriented sites). A deployment 

of multiple months aimed at a particular source area would generate a considerable amount of data that 

is consistent with the purpose of Type 2 sites. Two transportable units are desirable because they can be 

deployed as a pair, one for upwind and the other for downwind from suspected major precursor sources.

Using mobile or temporary sites to replace fixed Type 2 sites provides more flexibility and is more cost 

effective. 

If monitoring agencies already have mobile or temporary monitoring platforms, they can also use them 

for other purposes, such as for screening candidate sites for permanent monitoring sites. CASAC 

concludes that intensive ozone study campaigns are valuable to understand ozone issues and help 

develop ozone mitigation strategies, and mobile (including aircraft) and temporary sites can play an 

important role in these campaigns. There have been some discussions on highly-equipped 

mobile/transportable monitoring platforms for near road monitoring. There may be some synergy to 

combine this type of near road monitoring with a mobile/transportable PAMS platform that could be 

used for studies on air toxics hot spots, suspected transport issues, model validation, etc.

CASAC emphasizes the importance of proper documentation associated with mobile and temporary 

PAMS monitoring activities. The documentation should cover not only the typical monitoring 

information (e.g., location, date, time, etc.), but also the context within which the mobile or temporary 

sites are deployed (e.g., the reasons, surrounding sources, historic information at this location, etc.).

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 
7

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included? 

CASAC agrees that flexibility is desired because it will allow monitoring, research and data analysis to 

be tailored to the specific needs of each ozone problem area. This approach is also likely to provide the 

information needed to select regionally specific workable control strategies. In addition, a diverse group 

of stakeholders use PAMS data and thus the PAMS network should meet broad needs.

A national PAMS program is too rigid a structure to be able to adequately characterize the ozone 

problem in each area of the country. The parameter list would have to include monitoring for precursors 

and meteorological conditions that are not relevant in one area even though they are in another. This 

nationally uniform network design model is outdated and too resource intensive.

The responsibility for implementation of the PAMS program should remain with the state and local 

monitoring agencies. These agencies are the most knowledgeable about the sources and meteorological 

conditions in their regions and they have the ability and authority to implement control strategies. In 

some regions such as the northeast where multiple state and local monitoring agencies are within one 

ozone region, the research and data analysis aspects of the PAMS program should be coordinated. In the 

past, the Regional Planning Organization (RPO) model was an effective way to coordinate these 

activities. 

CASAC has further recommendations regarding how a more flexible PAMS program could be 

implemented. Data collection and quality assurance methods should be uniform to the extent possible to 

assist with data comparisons from one ozone region to another. This will also assist the varied 

stakeholders who use this data for other purposes. CASAC emphasizes that the flexible approach to 

PAMS should be implemented as a part of a specific strategy for each ozone area. The implementation 

should include documentation of the goal, the data analysis needed to address the goal and the network 

design and data collection required for the data analysis. This approach should eliminate the lack of 

attention to data, inefficient network design and the slow progress of model development. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

EPA’s current PAMS precursor monitoring requires that monitoring must be conducted throughout the 

months of June, July and August (as a minimum) when peak O3 values are expected in each area.

Alternate precursor monitoring periods may be submitted for approval to the EPA Administrator as a 

part of the annual monitoring network plan. EPA has noted that limiting the PAMS season to these three 

months saves resources by not requiring sampling during the off season. EPA has recognized that the 

usefulness of the data for model development and evaluation may be limited due to only measuring 

when conditions favor high ozone formation.

It would be desirable to extend the PAMS monitoring season beyond the current June, July, August 

sampling period. However, establishing the monitoring season should not be mandated and rigid; it 

should be flexible and adopted and coordinated on a regional airshed basis (i.e., within the same ozone 

region). This flexibility should not conflict with national goals for the PAMS program. A longer 

monitoring season would have many advantages. In some areas, such as Baton Rouge, there are more 

exceedances in May than in July or August. Thus extended PAMS monitoring would benefit the 

regulatory process. There is a springtime ozone bulge over most regions but the causes may differ by 
8

region. Extending the monitoring period of Type 2 PAMS into winter-time may provide better 

characterization of precursor emissions because the composition of emissions are generally unchanged 

and the composition is better preserved in winter-time than in summer-time. The extended monitoring 

would provide the opportunity to validate and to improve the performance of the Community Multiscale 

Air Quality Model (CMAQ) model. It is recognized that expanding the sampling season would require 

adjustment to other aspects of the monitoring program, such as fewer stations or different sampling 

frequencies. If an auto-GC is used (see responses to Charge Questions 11-12) at a PAMS site, the 

adjustment will be smaller. In general, it may be better to run auto-GC instruments year round at some 

sites, even if only a subset of the data are needed. 

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC 

list? 

As noted in EPA’s PAMSGram Volume 18 guidance document (2000), available at the following web 

address: http://www.epa.gov/ttn/amtic/files/ambient/pams/pamsgrm18.pdf, a large number of target 

Volatile Organic Chemical (VOC) compounds are being measured at PAMS sites. EPA has collected 

over fifteen years of data for these PAMS target VOC compounds. EPA wishes to revisit this list of 

compounds and hopes to identify a smaller list of compounds for analysis. EPA has noted that a smaller 

list may be desirable because there would be a decrease in analysis and reporting costs due to the lower 

number of compounds, and it may be possible to reduce the complexity and the cost of the use of a dual 

Gas Chromatograph (GC) detector that is required to analyze the complete list of target compounds if a 

shorter list of priority compounds is identified. In addition to removing compounds, EPA is also 

considering adding PAMS target VOC compounds such as biogenic compounds and compounds 

important for the understanding of SOA formation. Further, EPA is considering whether to add 

carbonyls to the PAMS target list for all sites.

Regarding the elimination of some target compounds, CASAC suggests that EPA consider cases where 

such compounds are important for certain airsheds. In such situations, CASAC recommends that 

measurements be retained.

EPA should consider the following general guidance in identifying targeted PAMS VOC species in 

order of importance. The ranking is not absolute and may vary depending on the location of the site: 

1. VOC species that are markers of emission sources such as biogenic (isoprene); gasoline vehicles 

(acetylene, benzene, isopentane); diesel vehicles (dodecane); solvents (n-decane); natural gas 

(ethane); and industry-specific markers;

2. VOC ozone forming potential;

3. VOC with measured concentrations above the lower limit of detection (LOD) for more than a 

certain percentage of the time and sites (to be determined by EPA); and

4. VOC species that are representative of urban, regional and rural environments;

Recognizing the importance of secondary objectives, the following should be considered depending on 

the characteristics of the site:

1. VOC contribution to secondary organic aerosol (SOA) forming potential; and

2. VOC identified as air toxics or likely air toxics precursor.

In addition, EPA should reduce the minimum national requirements for reporting of specific organic 

species required to be measured under the PAMS network, and provide criteria for such reporting.
9

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list? 

The AMMS Subcommittee did not have many specific suggestions for compounds to be added or 

subtracted from the current PAMS target list.

The Subcommittee agreed that each current species and potential additional species should be carefully 

and systematically considered using the criteria suggested in response to Charge Question 9. Although 

quantification of many compounds is relatively low-effort since they can be quantified as part of the 

same analytical run, there are still resources required in the quality assurance/quality control (QA/QC) 

and reporting of these compounds. In general, there is a high degree of co-linearity among compounds 

on the current PAMS VOC list. If a relatively large subset of the current target list is determined to be 

minimally useful based on established criteria, then there is potential for some resource savings and they 

should be considered for removal. At the same time, it is important to note that any eliminated 

compounds still need to be analytically resolved from target compounds to avoid confounding effects 

and over-estimation of the latter.

There was strong agreement that the addition of more biogenic species such as terpenes or 

sesquiterpenes would be helpful given the current trends of lower anthropogenic VOCs and the 

implications for rural areas. CASAC suggests adding additional compounds that may help to track 

emissions from additional non-mobile sources or more recent fuel formulations from mobile sources.

Addition of several isoprene daughter products, such as glyoxal, methylglyoxal, and methacrolein might 

be useful for elucidating photochemical production of both ozone and SOA.

CASAC further suggests an effort to identify the major unidentified peaks that are often observed in the 

TO-15 analysis and consider these compounds for addition if deemed important based on established 

criteria. Even if they remain unidentified, provisions for reporting them might allow a national 

assessment of their abundance. Similarly, CASAC suggests an examination of the late-eluting, 

unresolved carbon “slug,” whether those species could be further resolved using different methods, and 

whether those species may be important to ozone formation. 

Regarding which VOCs would be very important for rural air chemistry, biogenic VOCs are considered 

most important for ozone and SOA formation. However, another important reason to measure VOCs is 

because of their utility as tracers of sources or chemistry. With these considerations in mind, a 

prioritized list of eight VOCs that would be most important for rural air chemistry are as follows, with 

brief justifications. 

Isoprene. Isoprene is the most important VOC for ozone and SOA formation in non-urban air.

Emissions and their variability are very uncertain. Although the short lifetime of isoprene makes 

quantitative interpretation of observations difficult, even qualitative interpretation is very useful in terms 

of determining the presence of isoprene and its variability.

Acetylene. Acetylene is emitted solely by combustion and has an atmospheric lifetime of about 10 days.

It is more sensitive than CO as a tracer of combustion, because of its shorter lifetime and because it 

doesn’t have non-combustion sources. A positive correlation with acetylene provides irrefutable 

evidence of a combustion source.
10

Benzene. Benzene has a similar atmospheric lifetime to acetylene. Its principal source is combustion but 

evaporation is also significant. Benzene/acetylene ratios can be used to distinguish fossil fuel from 

biomass combustion. Benzene can also be used as a tracer of aromatics (e.g., Parrish et al., 2005). 

Ethane. The source of ethane is almost exclusively from fugitive natural gas releases during production, 

transport, and storage, unlike other VOCs. EPA's National Emission Inventory (NEI) database 

inventories considerably underestimate observations of ethane (e.g., Xiao et al., 2008) suggesting that 

natural gas emissions of methane in the U.S. are similarly underestimated. Ethane observations provide 

a great tracer for natural gas emissions.

n-butane, n-pentane. These come mainly from mobile sources. Butane has an atmospheric lifetime of 

about 1 day, pentane is much shorter. The pentane/butane ratio thus provides a tracer for the age of air 

since it was exposed to combustion sources, i.e., a photochemical clock.

Propene. It would be helpful to include an alkene such as propene in the list. Propene has the advantage 

that it is an important ozone precursor, it is often simulated explicitly in models (and hence can be used 

for model evaluation), and has both anthropogenic and biogenic sources (e.g., Goldstein et al., 1995).

Ethanol (or other markers for use in tracking long-term trends of biofuel emissions). Biofuel usage is 

expected to significantly increase, which will impact emissions from vehicles, distribution systems, and 

production. The committee recommends monitoring for biofuel marker because biofuels are becoming 

more widely used in the market.

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

Three options are currently allowed under PAMS for measuring the target VOC species during the 

PAMS monitoring period.

• Hourly measurements using an automatic gas chromatograph (auto-GC),

• Eight 3-hour canister samples every third day,

• One 3-hour canister sample in the morning and in the evening and continuous Total NonMethane Hydrocarbons (TNMH).

As EPA has noted, while these options provide flexibility, they also add complexity to the data set 

which may hamper data analysis.

The deployment and attributes of auto-GC versus canister based sampling systems is very much based 

on the PAMS monitoring objective(s) to be addressed.

Auto-GC Advantages: Field deployed auto-GCs provide (hourly average) diurnal concentrations (not 

possible with 24-hr avg. canister) that are particularly useful in evaluating air quality models and 

performing diagnostic emission attribution studies. These data can be provided on a near real-time basis 

and presented along with other precursor species (e.g., oxides of nitrogen and carbon monoxide) 

collected over similar averaging times. These data can be collected year round and may be aggregated to 

3-hr, 12-hr and 24-hr averages. 
11

Auto-GC Disadvantages: Operation and maintenance and data validation requires significant resources 

(highly skilled personnel and equipment/supplies) typically much greater than costs associated with the 

manual canisters. Not all VOCs are efficiently collected and resolved by auto GCs.

Manual Canister Advantages: Canister sampling systems are generally less resource intensive than the 

auto-GC systems, and utilize central GC laboratories with well established, reproducible cryo-focusing 

techniques. The canister systems will likely provide a lower cost solution (relative to auto-GCs) for 

annual trend analyses of VOCs and characterizing VOC composition by season.

Manual Canister Disadvantages: Canisters are not practical for high temporal resolution sampling (i.e., 

hourly average) and can have artifact species loss and transformation issues related to canister residence 

time.

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS 

sites? What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the 

PAMS network?

Auto-GCs for routine, semi-continuous measurement of PAMS compounds include a sample preconcentrator coupled to a gas chromatograph (GC) with a Flame Ionization Detector (FID) (Mass 

Spectrometer, MS, detectors have been used in special studies). Conventional systems are based on 

instruments developed for laboratory applications that have been modified for field use. Commonly used 

pre-concentrators for PAMS deployments include the Perkin Elmer ATD400 Automatic Thermal 

Desorption and the XonTech Model 930. Broadway and Tipler (2009) describe the latest version of the 

Perkin Elmer ATD400. Markes, an Agilent channel partner, makes a commercial pre-concentrator at 

least comparable to the Perkin Elmer ATD400, and has been deployed for field operations. The 

XonTech Model 930 (Oliver et al., 1996) appears to have also been used at some locations, especially in 

California. Typically two GC columns are needed to measure the full suite of PAMS target compounds.

A promising development in the auto-GC technology has been the design and integration of system 

components into packages specifically designed for ambient air measurements. One example is the 

Synspec Spectras Ozone Precursor Analyzer (Model 955 POCP, Synspec BV) that is a dual GC/detector 

system with one analyzer for C2-C5 compounds (Model 611) and another analyzer for C6-C10 

compounds (Model 811).

While the available technology appears promising, comprehensive evaluations are needed to assess 

suitability for national monitoring. There are many factors to be considered when evaluating available 

technology. For example, data quality, field robustness, required level of expertise to operate and 

maintain the analyzers, and cost should be assessed. A description of each available unit should be 

developed that includes compounds measured, minimum detection limits, reproducibility, recovery rate, 

accuracy, known interference, moisture management, power and space requirements, purchase costs, 

operating supply requirements, and standard operating procedures. The available units should be 

obtained and compared using the methods used in prior VOC comparison studies as a guide for methods 

and performance (see Dr. Chow’s individual comments for references). It is also necessary to update the 

field auto-GC requirements originally described in U.S. EPA (1998). 

Public comments provided by Dr. Babich (Connecticut Department of Environmental Protection) 

summarize one state’s efforts to evaluate one of the new generation analyzers (in this case, the Synspec 

955 PCOP) including comparisons to collocated conventional systems. Such evaluations should be 

encouraged and ideally coordinated with EPA to ensure a comprehensive evaluation emerges. AMMs 
12

recommends that the capabilities of new Auto-GCs for measuring oxygenated VOCs be assessed.

During the transition to new technologies, collocation of canisters with new auto-GCs is recommended. 

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

TNMH monitors provide an indication on the levels of VOC present in the atmosphere. They are the 

only practical method to gauge general, aggregated VOC levels with time resolutions comparable to the 

measurement of the other ozone precursor, NOy. These TNMH monitors have similar field operation 

characteristics and capital cost as other gaseous ambient air monitoring instruments. Having monitors 

for both ozone precursors (VOC and NOy) and ozone at similar time resolution provides a more 

complete picture on the atmospheric ozone formation process. 

CASAC recognizes the limitations of the TNMH monitors. They have different response factors for 

different VOC species. Therefore, different compounds present at the same volumetric concentrations 

may lead to very different TNMH readings. CASAC also recognizes that it is impossible to measure the 

exact total VOC concentrations by any other single monitor. To measure the exact total VOC 

concentrations, a monitoring system would have to capture, separate, detect, and quantify hundreds of 

VOC species in a timeframe preferably less than an hour. Between the choices of having no information 

on total atmospheric VOC levels and having an indicator of total atmospheric VOC levels from TNMH 

monitors, the latter is much more desirable because the end users of the PAMS data will have some idea 

about both VOC and NOy.

The sum of all VOC species analyzed by GC can be used as another measure of aggregated VOC. It is 

common to see some unresolved peaks at the end of GC analysis of PAMS samples when temperature is 

raised to purge the column. There may also be some unidentified VOC peaks even before the high 

temperature purge. The TNMH monitors can provide an indicator for the unidentified VOC, which can 

be calculated as the difference between the TNMH value and the sum of the speciated VOC by GC. 

In an area where the VOC composition is reasonably understood (e.g., near a major VOC source), the 

data generated by a relatively inexpensive TNMH monitor at very high time resolution can be used as a 

surrogate for some specific VOC species either as ozone precursors or air toxics. 

Some samples collected for PAMS analysis are taken when an elevated VOC level is suspected, i.e., the 

VOC exceeded a pre-determined trigger level. For these “triggered” samples (either for canister 

sampling or Auto-GC sampling), TNMH monitors provide the trigger signal to activate the samplers.

This role of TNMH should not be ignored. Even for TNMH monitors, a development that can lower the 

detection limit would be very important because the detection limit of current commercially available 

TNMH monitors may not be low enough for monitoring locations away from urban centers.

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

Carbonyls were identified as an important precursor to ozone and were added to the original PAMS 

VOC target list.

Due to concerns regarding the quality and cost of carbonyl sampling, in 2006 EPA removed the 

requirement to measure carbonyls (formaldehyde, acetaldehyde, and acetone) at all PAMS areas except 

those classified as severe or extreme for the 8-hour ozone standard. EPA asked CASAC to consider if 
13

advances have been made in carbonyl sampling that would warrant adding carbonyl sampling back to 

the required sampling at all VOC speciation sites.

There are many compelling scientific reasons to measure carbonyls. They are a very important part of 

ozone chemistry almost everywhere; for example, aldehydes such as formaldehyde and acetaldehyde are 

ubiquitous and have relatively high maximum incremental reactivity (MIR) values. Some carbonyls, 

formaldehyde in particular, are important air toxics.

CASAC recommends that carbonyl measurements not be required at all VOC speciation sites. However, 

it is important to measure carbonyls at select sites including those with high emissions (Type 2) and 

regional sites (Types 1 and 4). The choice of which compounds should be measured should be part of an 

overall strategy for a region. For example, carbonyl measurements at high emission sites are important 

because the incorporation of higher levels of ethanol into the nation’s gasoline supply is predicted to 

increase emissions of carbonyls such as acetaldehyde. The potential effects of these changes on ambient 

concentrations in high emission areas need to be monitored. Carbonyls also need to be monitored at 

more regional sites because, as important secondary species, they provide insight into the extent of 

oxidation. At these sites, carbonyls and other oxygenated organics likely contribute the bulk of the 

reactivity. Carbonyl data also provides an important constraint for oxidation mechanisms.

Carbonyls comprise a very broad class of atmospheric organics. Therefore it is important to identify a 

list of high priority carbonyls. EPA should evaluate the relative importance of carbonyls to their general 

ozone reactivity based on existing ambient and kinetic data. CASAC concludes that formaldehyde, 

acetaldehyde, methyl-glyoxal, glyoxal, and acrolein are higher priority carbonyls that should be 

considered for measurement under the PAMS program. These are all important oxidation products. The 

recent NATA analysis indicates that formaldehyde is one of the most important air toxics. CASAC 

concludes that acetone is a less important carbonyl for the PAMS program. Identifying a target list of 

carbonyls will help focus method development efforts.

Although it is important to measure carbonyls, CASAC has concerns about existing measurement 

methods, especially whether such methods are robust enough for routine monitoring in the PAMS 

network. To the extent that the methods can be shown to be accurate, then carbonyl measurements 

should be part of the routine PAMS program. If they are not reliable, CASAC concludes that it is 

important for EPA to support continued methods development and to incorporate carbonyls into PAMS 

as special studies.

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

The TO-11A method includes collection of carbonyls onto dinitrophenylhydrazine (DNPH) coated 

substrates, in situ derivitization of hydrazine to hydrazone, and desorption of the hydrazone in the 

laboratory with analysis by high-performance liquid chromatography (MS could also be used). Potential 

issues include positive and negative artifacts from contamination, reaction with ambient oxidants 

(especially ozone), incomplete collection efficiency, and carbonyl generation on the substrate. Steps 

have been taken to address some of these issues. For example, an ozone scrubber must be used with the 

DNPH cartridge. Improved preparation, handling, and storage presumably have improved the 

reproducibility (with additional room for improvement as noted below) but there remain concerns about 

accuracy. Collection efficiency depends on ambient conditions with relatively high humidity needed to 
14

promote the derivitization reaction. Comparisons to continuous analyzers often show the TO-11A 

method is biased low by up to 25% at low humidity. CASAC recommends that EPA conduct a more 

detailed review of the literature to assess the state of the science associated with the current TO-11A 

method for carbonyl sampling. Several research groups and analytical laboratories have extensive 

experience with carbonyl sampling and analysis; their perspectives would be valuable as part of the 

review. In addition, CASAC recommends a formal field evaluation of carbonyl methods. 

Quality assurance protocols for both field sampling and laboratory analysis operations should be 

reviewed and strengthened as warranted. Network-wide data quality assessments are not routinely 

conducted for PAMS. National Air Toxics Trends Sites (NATTS) also measure carbonyls by TO-11A.

The most-recent NATTS QA Annual Summary, conducted for calendar year 2008, demonstrates 

network-wide overall precision of ~20% for formaldehyde which is similar to many of the canisterbased VOC precisions. However, five of the 15 stations reported data that exceeded the 15% precision 

Measurement Quality Objective (MQO) at one station was nearly 50%. Many states perform the 

analysis in house. Proficiency testing of a single sample across fourteen laboratories was within the 25% 

bias MQO. Overall, these results are promising but do not reflect actual data quality since they are 

“ideal” laboratory generated samples. Thus these MQOs are a best-case scenario and still point out the 

need for refined QA/QC protocols and periodic QA assessments for PAMS.

Several carbonyls are often detected and reported by the analytical laboratories but only three -

formaldehyde, acetaldehyde, and acetone - are typically reported for NATTS. The NATTS carbonyls 

target analyte list should be evaluated with consideration of additional carbonyl compounds that may be 

of interest to PAMS. 

Charge Question 16: What other methods should be considered as an alternative to the manual TO11A method for carbonyl sampling?

There are a number of time-integrated, substrate based and continuous methods for measuring 

carbonyls. The substrate based methods are largely modest variations on the DNPH type methods. These 

should be pursued following some of the recommendations in the response to charge question 15.

CASAC agrees there may be promise in the emerging continuous methods. These include wet chemistry 

based approaches, differential optical absorption spectroscopy (DOAS), proton-transfer reaction mass 

spectrometry (chemical ionization) and tunable laser IR absorption spectroscopy. There are multiple 

vendors for several of these approaches. There have been some formal evaluations of these methods

with mixed results. In one study an atmospheric simulation chamber was used to evaluate five 

formaldehyde analyzers/samplers representing four different measurement principles (Wisthaler et al., 

2008). Numerous analytical issues were encountered and the degree of agreement between instruments 

varied depending on the chamber conditions. Overall, the agreement between methods was deemed 

“fair” and the authors also called for development of a validated reference standard. Continuous 

methods often measure individual or small numbers of carbonyls. Therefore development of continuous 

methods will need to be coordinated with the selection of high priority, target carbonyls.

Although none of the alternative carbonyl methods are ready for deployment in PAMS, carbonyls are 

important enough that there needs to be a focused development effort. Methods which can accurately 

and precisely measure a subset of high priority carbonyls such as acrolein, acetaldehyde and 
15

formaldehyde would be more useful than methods that produce poor quality data for a larger set of 

carbonyls. CASAC concludes that it is important for EPA to enable continued development of carbonyl 

measurement methods.

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for 

deployment in the PAMS network? What additional evaluations are necessary to determine the 

suitability for use in the PAMS network??

CASAC concludes that direct measurement NO2 or photolytic NO2 analyzers are suitable for 

deployment in the PAMS network. Currently, NO2 is required at Type 2 (maximum emission) PAMS 

sites, and NOy has been measured at Type 1 (upwind) and Type 3 (maximum O3) sites since 2006. There 

is ample evidence (e.g., Dunlea et al., 2007; Steinbacher et al., 2007; and Winer et al., 1974) that NO2 is 

overestimated by FRM monitors that use a catalyst to convert NO2 and other compounds (e.g., PAN, 

HNO3, nitrate) to NO, especially in rural and remote locations where NOx may not be the dominant 

species in NOy. In addition, ammonium nitrate collected on a pre-filter at cooler temperatures can 

volatilize to HNO3 during warmer parts of the day, thereby increasing the apparent NO2 (Chow et al., 

2002; and Chow et al., 2005). Another problem with conventional NOx analyzers stems from use of a 

single detector (time-sharing) to measure NO and NO2. This synchronization effect occurs when 

atmospheric NOx is changing rapidly. Under these conditions, the difference between the NOx channel 

and the NO channel can have an unreasonably large absolute values (positive or negative). Care needs to 

be exercised to flag unreasonably high or low NO2 concentrations during data processing and/or 

validation. 

Several photolytic and cavity ringdown systems are commercially available, and all of these require 

further evaluation before they can be considered viable for PAMS. Photolytic converters (e.g., 

Castellanos et al., 2009; Nakamura et al., 2003; and Thornton et al., 2003) use ultraviolet to violet light 

to photolyze NO2 to NO plus an oxygen radical. Reported converter efficiencies range from 30% to 

90%. Conversion stability depends on the stability of the light source, ambient ozone concentrations and 

the cleanliness of the photolysis chamber. Intense light sources that heat the sample should be avoided, 

as they may cause positive artifacts due to shifts in thermal equilibrium (e.g., peroxyacetyl nitrate (PAN) 

and PAN homologues to NO2). Residence time downstream of the photolytic converter should be 

minimized in order to prevent significant back reaction with ambient ozone. In principle, a single 

analyzer equipped with a photolytic converter for NO2 and a catalytic converter for NOy could be used 

to measure NO, NO2, NOx, NOy and NOz (i.e., NOy-NOx). This 3-channel approach may be highly 

successful in rural/remote areas, but could aggravate synchronization effects in urban areas, because the 

detector would be time-shared among three channels instead of two.

Cavity ringdown (CRD) instruments (e.g., Fuchs et al., 2009; and Osthoff et al., 2006) are specific to 

NO2 and appear to have required sensitivity for measurements in rural areas (0.1 ppb or better); 

however, very little information is available on the long-term (i.e., 6 months or more) operation of such 

analyzers. CRD analyzers offer the promise of artifact-free NO2 measurements, but they are stand-alone 

instruments that do not (at present) provide any information on NO, NOx or NOy. Luminol detectors 

(e.g., Gaffney et al., 1999; and Kelly et al., 1990) separate PAN from NO2, but they tend to be 

operationally messy and unreliable. 

As with the field auto-GCs, available NO2 monitors need to be field compared in different environments 

during different seasons and over extended periods of time. Standard operating procedures and data 

validation criteria need to be developed and vetted. Cleaning, calibration, and zeroing intervals need to 
16

be specified. Minimum detection limits, reproducibility, power and space requirements, purchase costs, 

and operating supplies also need to be defined. Previous comparison studies (e.g., Dunlea et al., 2007; 

Vaughan et al., 1997; and Zenker et al., 1998) can be used as a guide for methodology and expected 

tolerances.

Citations and additional references that support the above response to Charge Question 17 are provided 

in Enclosure C. 

Charge Question 18: What observational approaches (surface based sondes and optical remote 

sensing, aircraft platforms, satellites) are best suited to assist such assessments? What routinely 

collected surface measurements and in what locations would complement vertical profile and total 

column observations?

It is important to characterize background ozone concentrations, and delineating contributions from 

local and regional sources and long range transport. Such contributions have evolved into important 

assessment needs to support both the standards setting risk assessment process and subsequent 

implementation. A number of options exist to obtain ozone and nitrogen oxide vertical profile 

information, including surface based sondes, optical remote sensing, aircraft platforms, and satellites. 

Satellite remote sensing offers promise to improve understanding of the spatial distribution of ozone 

precursor emissions, ozone formation, and transport. The daily coverage of satellites along with ~10km 

spatial resolution constitutes a consistent global-scale dataset for several atmospheric chemical 

constituents (Hoff and Christopher, 2009). For the PAMs program, this information is more suited to 

analysis of regional area-wide biogenic precursor concentrations and is not as useful for small scale 

sources or for analysis of ozone episodes (Millet et al., 2008).

Satellite sensors have numerous limitations in accuracy, precision and spatio-temporal coverage. The 

column-concentrations measurements are difficult to calibrate and have interferences from clouds, other 

chemicals and surface reflectance. Satellite observations are best used in conjunction with other 

observations and/or chemical transport models. Surface-based column observations e.g. for ozone 

(Dobson instruments) and aerosol optical thickness (Sun-photometers) provide suitable, high-grade 

comparison data for the satellite sensors. These should be utilized in conjunction with the satellite data.

A variety of innovative monitoring approaches may be necessary in different areas of the country.

Various approaches and technologies should be considered and funded under the PAMS program if a 

state or local agency can justify the need for this data. For instance, satellite data have recently been 

used to determine land use factors to estimate biogenic emissions. Land based remote sensing 

techniques can be useful for source characterization for area wide sources such as marine and airports, 

railyards, and large industrial facilities.

Observations from commercial aircraft would provide a very useful source of data for vertical profiling 

relevant to long-range transport of ozone. The value of these data has been demonstrated with the 

MOZAIC program in Europe. Although it is resource intensive, EPA should consider support for such a 

program for the US. IAGOS would be an excellent opportunity to develop this as an interagency 

initiative.

Ozonesondes are similarly useful as long as they offer a sufficiently high-density record to generate 

statistics. Weekly ozonesonde measurements are not very useful because it is difficult to interpret the 
17

snapshot data measured by the sonde. Daily measurements at a few selected sites would be of 

considerable value, as has been demonstrated by the use made of the Trinidad Head daily ozonesonde 

data.

Direct satellite observations of tropospheric ozone have too much noise to detect individual events, and 

this situation is unlikely to change until the GEO-CAPE geostationary satellite gets launched in the early 

2020s. Satellite observations of CO and aerosol optical depth (AOD) are more useful for detecting 

events such as fire or dust plumes. The value of these satellite data could be augmented by high-quality 

surface CO and AOD data at the PAMS sites. 

A relatively inexpensive addition to PAMS sites would be a ground-based sun photometer measurement 

of AOD, as is done in the AERONET network. This would provide a link between the satellite 

observations of AOD and the conditions measured at the site. In addition, the concurrent measurements 

of AOD and PM2.5 at the site would assist in relating the satellite AOD data to surface air quality.

One would expect ground-based lidar to provide the best source of vertical information over the PAMS 

sites, but cost is prohibitive except perhaps for aerosol lidars (ceilometers). Even then, CASAC finds 

that states and other air quality organizations do not regularly use routine ground-based aerosol lidar 

data because interpretation is complicated by cloud cover. Therefore, CASAC does not recommend the 

addition of lidars at the PAMS sites.

Wind, temperature, and humidity observations from radiosonde and aircraft are the main sources of 

upper air information for meteorology. For mesoscale meteorology, the horizontal coverage of 

radiosondes is too sparse. Aircraft observations through Aircraft Meteorological Data Relay (AMDAR) 

sample an atmospheric profile in the vicinity of airports (see Charge Question 19). However, not all 

aircraft are equipped with AMDAR or have the system activated. Observations inferred from an 

enhanced tracking and ranging (TAR) air traffic control radar can fill this gap. See S. de Haan (2011).

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites? 

State and local monitoring agencies are required to make both surface and upper-air meteorological 

measurements as part of the PAMS rulemaking. The PAMS regulation does not require a specific list of 

the meteorological variables to be monitored. Current PAMS guidance recommends a list of parameters 

to be monitored, including wind direction, wind speed, temperature, humidity, atmospheric pressure, 

precipitation, solar radiation, UV radiation, and mixing height. EPA is interested in alternatives to 

collecting mixing height data and upper air wind speed data. EPA is also interested in exploring if and 

how NOAA upper air data can be used to meet the PAMS upper air data needs.

CASAC concludes it would be useful to collect upper air data at or near PAMS sites, but the utility of 

upper air wind speed and wind direction data greatly depends on local or regional needs. In some areas 

of the country, data from a single upper air wind monitor can represent a wide region. In other areas 

with more complex topography and recirculation patterns, several monitors may be needed. Therefore, 

such measurements should not be required as necessary components at all or most PAMS sites or areas, 

but instead should be supported as needed based on regional modeling needs and uncertainties.

Upper air wind data taken at multiple sites is important in areas with complex terrain, strong upper-level 

recirculations, upslope/downslope flow, marine boundary layers, and strong sea breezes. The 
18

measurements are useful in developing and testing conceptual frameworks of upper air transport and 

mixing at finer scales to evaluate modeling efforts. While finer scale resolution may not be needed for 

national applications of CMAQ and MM5, local or regional models with 2-5 km grid scale resolution 

need to account for these meteorological phenomena. Upper air wind measurements may not need to be 

routine or long-term given that these conceptual frameworks are not likely to change over time, although 

some continuous measures are being used for forecasting purposes.

If other sources of upper air wind data are deemed sufficient for modeling needs, then PAMS 

requirements to collect such data should be considered met. The current network of PAMS upper air 

wind profilers are expensive to maintain and the hardware is nearing the end of its expected lifespan.

Furthermore, some PAMS upper air wind data are used infrequently and costs of the data may not be 

justified; EPA should consider ending the requirement for collecting such data. Disinvestment in these 

measurements may be appropriate in some areas of the country.

CASAC concludes that EPA should consider alternatives to the classic, expensive and noisy 

RASS/Profiler upper air instruments for PAMS (also see response to Charge Question 20). NOAA 

collects upper air data through the ACARS (Aircraft Communications Addressing and Reporting 

System) and AMDAR (Aircraft Meteorological Data Relay) observational systems which provide 

reports from commercial aircraft during flight. Such data may be useful for the PAMS program. See 

http://www.nco.ncep.noaa.gov/sib/restricted_data/restricted_data_pmb/acars+amdar/. EPA should work 

with NOAA to help ensure that this data are accessible to states and state organizations.

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

The PAMS rule requires meteorological monitoring but is not specific about which meteorological 

parameters must be measured. When the PAMS network was established, most areas opted to install 

RADAR profilers. These profilers provide measurements of wind speed and direction with relatively 

high vertical resolution (60-160 m, up to maximum altitudes of 1.5 or 4 km). These PAMS profilers are 

now old and will require expensive upgrades if they are to continue to operate in the PAMS network.

EPA seeks guidance regarding other options for obtaining the required meteorological information. One 

possibility is to use wind profile data from other agencies, such as NOAA, which generally provide wind 

speeds and directions with lower vertical resolution (250 m) at altitudes up to 16.25 km. Another 

possibility would be to use ceilometers to measure mixing heights. See Emeis et al., 2008; Eresmaa et 

al., 2006; and Tsaknakis et al (2011).

The Subcommittee’s discussion focused on two points: (i) is good use routinely made of data from the 

PAMS RADAR profilers?, and (ii) where available, could the lower resolution data from profilers 

operated by other agencies be used in place of the PAMS RADAR profilers? While there are examples 

of limited use of the data (e.g. to obtain supporting data for special studies such as identifying flow 

patterns associated with elevated ozone and PM layers measured by aircraft) overall the data are 

underutilized and its collection does not justify the cost.

Data for meteorological fields from other sources, such as NOAA and NWS networks, are already being 

used for modeling ozone concentrations. Discontinuing the use of the PAMS RADAR profilers would 

not seriously impair ozone modeling capabilities, since other sources of data are generally adequate for 

most forecasting or SIP modeling purposes. Some committee members suggested that ceilometers could 

provide data that might be useful by local or regional modeling in targeted areas, such as near coasts.
19

Upper air data (temperature and wind) are collected by NOAA from commercial aircraft under the 

ACARS and AMDAR observing systems as noted in the previous charge question response.

These data could be very useful, especially near coastal areas. EPA should work with NOAA to help 

ensure that this data are accessible to states and state organizations. It would be helpful if existing 

meteorological data storage systems like MADIS or “FED” (the new VIEWS) could be used. There has 

been much discussion regarding inter-agency cooperation; this is a good example of where that approach 

has value.

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted?

As part of the grant guidance EPA provides for how the PAMS grant money should be utilized, the EPA 

states that 25% of the PAMS funds should be spent on data analysis. However, over the years, states and 

EPA have been criticized for not effectively making use of PAMS data. This may be due in part to the 

relatively limited flexibility provided for the design of the network. Flexibility in PAMS requirements 

would enhance the potential for data analysis.

As part of the effort to prioritize, refine and identify new objectives for PAMS, EPA should identify 

specific data analysis goals for each objective. A component of this would be to determine progress 

towards achieving that objective and be facilitated by defining more specific objectives. As part of 

creating a more flexible set of requirements, state and local agencies performing PAMS monitoring need 

to identify analyses necessary to support specific objectives.

Although PAMS data have not been widely used in academic analyses, PAMS data are valuable to local 

and state agencies because they provide substantial insight into the character in a particular air shed. A 

significant portion of this analysis has been somewhat informal and not documented in traditional 

reports.

CASAC suggests there are national or regional analyses that could be done to investigate ozone 

formation potential, secondary organic aerosol formation model development and performance, and 

effectiveness of emission control strategies. The conduct of these analyses could benefit from 

incentivized partnerships between state and academic institutions.

Standard temporal analyses should be performed for all PAMS sits, including: Secular trends, seasonal, 

weekly and when possible diurnal pattern. These would help inferring sources contributions, as well as 

transformation and removal processes. Episodocity analyses derived from concentration distribution 

functions would indicate which PAMS species have persistent sources and which compounds originate 

from episodic sources. 

Combining the PAMS concentration data with temperature, humidity and other weather parameters are 

indicative of meteorological influences on ozone and its precursors. Combining concentration data with 

back-trajectories yields information about the general direction of sources. Back-trajectory analysis for 

multiple sites can be used to triangulate the location of source areas. 

Data analysis at the national and regional levels should focus on trending, accountability analyses for 

emission reduction programs, and evaluation of air quality models. Trending must be carefully 
20

conducted given the range of objectives that are used to site monitors. For example, accountability 

analyses on the ozone precursors profile, ozone itself, and on other pollutants should examine the 

impacts of increased ethanol use in motor vehicle fuels. As data analyses are carried out, there should be 

interaction with data users to assure that the analyses will address issues associated with air quality 

modeling (e.g., CMAQ and NATA). PAMS data could also be used to conduct national or regional 

analyses to investigate ozone formation potential and secondary organic aerosol formation model 

development. Not conducting these sorts of analyses seems like a significant missed opportunity that 

could benefit from incentivized partnerships between state and other institutions.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

A detailed response to this charge question needs to be tethered to the monitoring objectives and 

implementation strategy for PAMS. These aspects might well change through the PAMS re-engineering 

process. That said, the Subcommittee offers the following perspectives on data analyses. Unlike 

monitoring programs to determine NAAQS compliance, the main purpose of PAMS is to support air 

quality management by providing insights into the nature of the ozone air quality problem. Thus, PAMS 

data must be effectively used to justify the investment in the PAMS program. 

Analyses should likely be implemented at state, regional and national levels. As part of EPA’s PAMS 

grant guidance, EPA states that currently 25% of PAMS funds should be set aside for data analysis.

These funds are included in the state/local agency allocations and the general feeling is that these funds 

are in many cases being used for broader needs within the monitoring program. A re-engineered PAMS 

program should include a mechanism to link the PAMS funding to accountability of the monitoring 

agencies’ use of their PAMS data. While the need for a data analysis funding set aside (25% or some 

other level) is not clear, approval of PAMS allocations should be contingent upon the receiving agency 

providing a detailed data analysis plan with follow-up that the analysis has been conducted. This 

approach acknowledges that the state/local agencies should have flexibility to design their PAMS 

program to address airshed-specific needs and plans for data analysis should be considered an integral 

part of the program.

Consistent with the above philosophy, the Subcommittee envisions a significant role for regional 

planning organizations (RPO) in planning both PAMS measurement strategies and data analysis when 

coordination between states is needed to holistically address ozone air quality issues. Several RPOs have 

already been serving this role including the contracting of data analyses.

A re-engineered PAMS program should have mechanisms in place that would promote a closer 

coordination and collaboration with the air quality modeling community. EPA may consider sponsoring 

an annual or bi-annual workshop or symposium to promote data analysis and collaboration with other 

related programs and communities.

In support of the above considerations, CASAC strongly urges that EPA consider ways to update PAMS 

data analysis tools, including the development of new tools as warranted, with attention given to the 

spectrum of analysis objectives at the state, regional, and national level. The lack of easy access to 

PAMS data is often cited as a major obstacle to its use. Therefore, the data must be available through a 

user-friendly portal to promote more widespread use. EPA should leverage the infrastructure and 

success of other programs such as VIEWS (now FED) did for IMPROVE. Some funds should be set 
21

aside to develop national scale web-based data analysis tools similar to those available on the FED 

website, but tailored to PAMS data analysis. FED provides a successful and existing infrastructure for 

this purpose.

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis? 

As part of EPA’s PAMS grant guidance, EPA states that currently 25% of PAMS funds should be set 

aside for targeted data analysis (e.g., trend analysis, control strategy analysis, or model validation) 

beyond routine reporting. However, it appears that these monies are not being spent entirely on data 

analysis but are also used to implement the monitoring network. In these times of limited resources, it 

may be difficult for state and local agencies to give up 25% of the money dedicated to PAMS. 

There is also a need for more information from EPA on what their data analysis expectations are? It 

would be very helpful to identify or develop case studies on data analyses (include how and why 

specific analysis were conducted) that can be circulated so that people can learn from what others did. 

EPA should consider multiple mechanisms for conducting data analysis, including a more periodic 

focused effort using a competitive grant process to produce more useful results. CASAC concludes it 

would be helpful if EPA funded a competitive grants program every few years specifically focused on 

the analysis of PAMS data; this has been done in the air toxics program. For example, four or five 

separate PAMS data analysis projects could be funded with each round of grants. The competitive 

process would give EPA an idea of what can be done with the data and what the research needs are with 

respect to such data. This data analysis should be done on a regional or airshed basis. Some of the 

PAMS data analysis funds should be spent on making the data more accessible as noted in Question 22.
C-1

Enclosure C

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conversion technique during the Transport and Chemical Evolution Over the Pacific (TRACE-P) 

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systems. http://www.nco.ncep.noaa.gov/sib/restricted_data/restricted_data_pmb/acars+amdar/.

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Baynard, T.; Dube, W.P.; Ciciora, and S.J.; Ravishankara, A.R. 2006. Measurement of atmospheric NO2

by pulsed cavity ring-down spectroscopy. Journal of Geophysical Research 111:D12305. 

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York City. Atmospheric Environment 37:3639-3651.

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Demerjian, H.D. Felton, G. Boynton, Y. He, X. Zhou, and J. Hou. 2006. Behavior of OH and HO2 in the 

Winter Atmosphere in New York City. Atmospheric Environment 40:S252-S263.

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and Alicke, B. 2003. Comparisons of in situ and long path measurements of NO2 in urban plumes.

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Georgoussis, G., and Avdikos, G. 2011. Inter-comparison of lidar and ceilometer retrievals for aerosol 

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Müller, K.; Solomon, S.J.; Steinbrecher, R.; Tillmann, R.; and Brauers, T. 2008. Technical Note: 

Intercomparison of formaldehyde measurements at the atmosphere simulation chamber SAPHIR.

Atmospheric Chemistry and Physics 8:2189-2200. www.atmos-chem-phys.net/8/2189/2008/.

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A.S.H.; and Hueglin, C. 2007. Nitrogen oxide measurements at rural sites in Switzerland: Bias of 

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D-1

Enclosure D

Compilation of Comments from Individual Members of the CASAC Air Monitoring 

and Methods Subcommittee (AMMS)

MR. GEORGE ALLEN............................................................................................................ D-2

DR. LINDA BONANNO .......................................................................................................... D-4

DR. DOUG BURNS .................................................................................................................. D-8

DR. JUDITH CHOW................................................................................................................ D-9

DR. KENNETH DEMERJIAN ............................................................................................. D-33

MR. DIRK FELTON.............................................................................................................. D-39

DR. PHIL FINE ...................................................................................................................... D-46

DR. PHIL HOPKE.................................................................................................................. D-51

DR. RUDOLF HUSAR........................................................................................................... D-56

DR. PETER H. MCMURRY ................................................................................................. D-60

DR. ALLEN ROBINSON....................................................................................................... D-62

DR. ARMISTEAD (TED) RUSSELL................................................................................... D-68

DR. JAMIE SCHAUER ......................................................................................................... D-71

DR. JAY TURNER ................................................................................................................. D-75

DR. YOUSHENG ZENG........................................................................................................ D-77
D-2

Comments from Mr. George Allen

Charge Question 12: Are the new commercially available auto-GCs appropriate for use 

at PAMS sites? What additional evaluations are necessary to determine the suitability of 

auto-GC’s for use in the PAMS network? 

Dr. Babich’s public comments on new PAMS GC technologies are posted with other 

comments for this meeting. His experience with new GC methods is encouraging, and is 

important to consider for this charge question. It is time to move from older and fragile 

“lab” GC PAMS technologies and toward robust field instruments that can measure key 

biogenic species. ORD should be supporting this effort.

Charge Question 13: Role, if any, of TNMH Monitors in PAMS program.

Existing TNMH (or TNMOC) analyzers may be suitable for urban areas where TNMH 

levels are elevated, but method sensitivity is not sufficient for non-urban sites. While it 

would be useful to have a TNMH measurement to compare to total “PAMS HC”, existing 

TNMH analyzers have a varying response to different VOC compounds, reducing the 

value of the measurement.

Charge Questions 14, 15, and 16: Need for and issues with Carbonyl Sampling at PAMS 

sites.

Carbonyl measurements (primarily formaldehyde and acetaldehyde) are critical for the 

PAMS and air toxic programs, but have not been measured with consistent or known data 

quality. The existing DNPH sorbent tube method is not sufficiently robust to fill this 

need, but other methods suitable for routine and widely deployed network use are not yet 

available. ORD should support development and evaluation of new methods.

Charge Question 17: Suitability of Direct Measurement NO2 or Photolytic NO2 

Analyzers For Deployment in PAMS Network

“True” photolytic NO2 and robust NOy measurements in a single analyzer are highly 

desirable at all PAMS sites, including urban sites; this is the only practical way to get a 

good measurement of NOz. Commercial instruments meeting this need are presently in 

development.
D-3

Charge Questions 21 and 22: PAMS data analysis.

Last year NESCAUM initiated review of PAMS data needs and analysis covering the NE 

corridor. The following two documents summarize the results:

http://www.nescaum.org/documents/mac/mac-committee-meeting-3/allen-pams-wgreview.pdf/

and

http://www.marama.org/presentations/2011_DataAnalysis/Underhill_NESCAUM_PAM

SWorkgroup_jan2011pdf.pdf

Tom Downs from Maine-DEP analyzed all available data from all the PAMS sites in the 

OTC domain; the results for each site are at:

http://www.maine.gov/dep/ftp/DEP_PAMS/NESCAUM_PAMS_ANALYSES/

A template used for this analysis is at:

http://www.maine.gov/dep/ftp/DEP_PAMS/NESCAUM_PAMS_ANALYSES/TEMPLA

TE%20hour%20or%203-hr%20site%20PAMS%20ANALYSIS.zip

The PAMS community (both data generators and users) would benefit from user-friendly 

access to PAMS data along with web-based tools to assist in data analysis; a major 

obstacle to routine use of the data is the lack of such access and tools. In the IMPROVE / 

RPO-regional haze community, the VIEWS web site has been a valuable source of data 

and analysis tools over the last decade. Recently, VIEWS has been moved to a new 

funding structure and web site: http://views.cira.colostate.edu/fed/

This is a continuation and expansion of VIEWS, funded by FLMs. It is intended to 

include water data also.

It would be very useful if PAMS data were included in the FED database, along with 

some PAMS- specific screening, validation, and analytical tools. This concept is not new; 

in 2002, EPA funded a project that added air toxics data to VIEWS:

http://views.cira.colostate.edu/web/Projects/ATDA.aspx

but that has not been updated for many years. A substantial amount of other relevant 

AQS data are already in FED, including ozone. For screening tools, FED could 

incorporate existing screening functions used in VOCDat or similar tools into the system.

For analysis tools, FED could implement the concepts behind the analytical template that 

Tom Downs (Maine DEP) put together for the Nescaum PAMS analysis last year.

Finally, EPA-OAQPS might be able to fund this effort with the $150k/year taken off the 

top of PAMS STAG program funds for national scale data analysis every year.
D-4

Comments from Dr. Linda Bonanno

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any should be deemphasized or eliminated? 

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

Charge questions 1 and 2 can be combined as stated below.

Objectives may need to be revised on regional basis because national objectives may be different from 

regional objectives

Original objectives can be reworded as suggested below.

1) Track and verify trends, transport, background concentrations and atmospheric chemistry of ozone 

and its precursors. This will assist in assessing key constituents in ozone formation and VOC and NOx 

mitigation emission strategies and target controls [e.g. to assess VOC trends in response to: a) to phase 

1& 2 RFG (with specific look at catalytic converter performance in response to Tier 2 gasoline sulfur 

control and mobile source air toxic MSAT controls; b) introduction of low sulfur diesel fuel; c) 2007 

diesel emission emissions standard; d) the economic recession; and e) introduction of renewable fuels].

2) Provide local, current meteorological and ambient data to serve as initial and boundary conditions for 

photochemical grid models, for baseline information for model evaluation and to improve forecasting. 

This can be enhanced by special studies that allow wider spatial measurements. This could be 

accomplished with “mobile” sites that would be moved periodically. 

3) Provide a representative, speciated ambient air database which is characteristic of source emission 

impacts to improve emission inventories, corroborate progress towards attainment, and enhance air 

toxics monitoring network and exposure modeling. 

Additional objectives include:

1) Separate natural biogenic precursors from anthropogenic biogenic precursors because anthropogenic 

precursors may be subject to mitigation strategies, e.g., CAFOs and eutrified water bodies. 

2) Provide compound specific diurnal patterns to evaluate emission profiles (as specified in emissions 

models by source) and for evaluation of the air quality modeling system overall (e.g., see Doraiswamy et 

al., 2009 and Ren et al.,2003, Ren et al., 2006). 

3) Measurement of SOA precursors with an emphasis on developing effective strategies for reduction of 

SOA

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites? 
D-5

Disadvantages include that multi state control over a PAMS network, probably better to have those 

PAMs sites

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage? 

Yes potentially in areas where extensive fracking is occurring.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non attainment areas, all 

urban NCore sites) ? 

It would depend on available resources and regional needs. I don't think it should be required but can be 

worked into the 'flexibility' of the PAMS network.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program? 

Mobile/temporary sites can be a cost effective way to capture better spatial coverage for modeling, 

forecasting and emission inventory purposes. They may also serve as a way to reduce the total # of 

permanent sites and therefore resources expended

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included? 

Flexibility region to region (airshed to airshed) will allow each region to best capture the compounds 

related to ozone formation. That being said, it is important to have consistent QA procedures in place. 

Some special studies could be done to compare different methods, sampling periods etc so that region to 

region comparisons can be done. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors? 

Should be determined on a case by case basis (regionally). 

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list? 

Compounds that are rarely detected should be deleted from the list.
D-6

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list? 

For carbonyls, most important are acrolein, acetaldehyde and formaldehyde 

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs? 

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network? 

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program? 

Charge Question 14: Should carbonyls be required at all VOC speciation sites? 

Yes

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling? 

Precision and accuracy. 

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling? 

There are some methods based on TO-11A (DNPH) that appear promising (Uchiyama, S., et al., 2010).

More work needs to be done to determine precision and accuracy before deploying in the field. 

Uchiyama, S., Inaba Y., Kunugita, N., Determination of acrolein and other carbonyls in cigarette smoke 

using coupled silica cartridges impregnated with hydroquinone and 2,4-dinitrophenylhydrazine. J Chrom 

A 1217 (2010) 4383-4388.

Charge Question 17: Are direct measurement NO2 or photolytic analyzers suitable for deployment in 

the PAMS network? What additional evaluations are necessary to determine their suitability for use in 

the PAMS network? 

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations? 
D-7

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites? 

Not at all sites, best to choose regionally representative locations

Charge Question 20: How should NOAA data be incorporated into the PAMS program? 

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted?

Data analyses should focus on objectives of network and also include ideas from independent 

researchers which may or may not be in line with PAMS objectives.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level? 

Implementation of PAMS data analysis should be on a regional (air shed) basis and also on a national 

level. Competitive bids or subcontractor, competitive preferred to getting independent researchers to 

show EPA what can be done with the data and what their data analysis needs are. The RFP could 

emphasize the objectives of the PAMS network.

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis? 

Although 25% is informally set aside for data analysis, it appears that these monies are not being spent 

on data analysis but on implementing the monitoring network. In these times of limited resources, it may 

be difficult for states to give up 25% of the money dedicated to PAMS. It may be a more reasonable 

approach for EPA to set aside 3-5% of the 14 million every 3 years for competitive grants for data 

analysis of PAMS data. The competitive process will give USEPA an idea of what can be done with the 

data and what the research needs are in respect to such data.
D-8

Comments from Dr. Doug Burns

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

• Current network design does not allow flexibility in choosing monitoring locations. Might 

consider allowing states the flexibility to ascertain whether Type 2 sites are located 

appropriately.

• Consider strategies that allow wider spatial measurements that might better support model 

evaluation. This could be accomplished with “mobile” sites that would be moved periodically. 

• Consider requiring some measurements outside of the June-August period. Wouldn’t 

concentrations be expected to be about as high or higher in September than June? For example, 

Bloomer et al., 2010 show that the > 40 ppb ozone contour for eastern rural sites (based on data 

from 5 eastern CASTNET sites) extends from May through October.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

It seems that there are two potential elements to this question:

a. To what extent are we certain that the areas currently classified as serious or above are accurate 

today? There have been major increases in population in many urban areas since the 1990s such 

as Orlando, Charlotte, Las Vegas, etc. Is it possible that these and other urban areas should be 

classified as “serious” ozone areas given current conditions?

b. Is the importance of models sufficient in a regulatory context to consider modeling needs as part 

of PAMS? And would appropriate models benefit from the availability of more spatially 

widespread ozone and precursor measurements? If the answer is yes to these questions, then 

more widespread measurements should be encouraged.

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

Consideration should be given to incorporating NOAA upper air wind data into the PAMS program. The 

PROFILER site locations are clearly not adequate to address PAMS needs. However, it appears that 

upper air wind data available through the CAP PROFILER web site includes sites near to several of the 

severe and non-attainment areas such as NYC, Boston, Baltimore/Washington DC, LA, Houston, etc. 

However, data do not appear to be available for all ozone non-attainment areas. Some key questions 

need to be addressed such as whether data available through NOAA are of sufficient spatial and 

temporal resolution to meet the needs of PAMS, and the expected long-term viability of the currently 

available sites considering various funding sources.
D-9

Comments from Dr. Judith Chow

Charge Question 1: How should EPA prioritize the current PAMS objectives?

The six PAMS objectives could be shortened and made less redundant. They have been re-ordered 

below with some comments on how well they are being met as follows:

i. Provide a speciated ambient air database which is both representative and useful for ascertaining 

ambient profiles and distinguishing among various individual VOC. These data can later be used as 

evaluation tools for control strategies, cost-effectiveness, and for understanding the mechanisms of 

pollutant transport. 

This has been, and still should be, the primary objective for PAMS, to provide a 

reliable data set that can be used for a wide range of purposes. Unfortunately, the data 

documentation and access is deficient. The PAMS description websites (U.S.EPA, 

2011a; 2011b) haven’t been updated since the late 1990s, so it is difficult to figure out 

what is measured and at which location(s). For example: 1) “AQS Discoverer” requires 

jumping through a lot of hoops, and it is not clear that PAMS data can be found there; 

2) “Query AQS Data” states “Notice: This data is not being updated. Last update on 

March 4, 2010”; and 3) the “Download AQS data” seems to have all the data in flat 

files that look like Figure 1, but there is a lot of searching needed to find site codes and 

parameter codes to assemble a useful data base. This may be part of the reason that 

PAMS data are minimally exploited. EPA should consider updating the PAMS 

websites to make them more user-friendly, including better data documentation. 

VIEWS (2010) provides a better example of a query structure and data extraction 

method that is useful to investigators. 

Figure 1. Example of PAMS data read into an Excel Spreadsheet using 2011 VOC data 

downloaded from U.S. EPA (2011c)
D-10

ii. Provide ambient data measurements which would allow later preparation of unadjusted and 

adjusted pollutant trends reports. 

A consistently-acquired data set is needed to determine the effectiveness of control 

strategies. The data base has been only minimally exploited for this purpose (Blanchard 

et al., 2010; Fortin et al., 2005; McCarthy et al., 2007), but the results show that some 

of the control strategies have been effective. This is important for the purposes of 

accountability in multipollutant air quality management (Hidy and Pennell, 2010; van 

Erp et al., 2008).

iii. Provide a representative, speciated ambient air database which is characteristic of source emission 

impacts. These data can be particularly useful in analyzing emissions inventory issues and 

corroborating progress toward attainment. 

This objective is also important for accountability. Again, the PAMS data have been 

minimally exploited for this purpose (Brown et al., 2007; Cardelino and Chameides, 

2000; Choi and Ehrman, 2004; Fujita, 2001; Gan and Hopke, 2003; Henry et al., 2002; 

Leuchner and Rappengluck, 2010; Mukerjee et al., 2004; Scheff and Yu, 1997; Xie and 

Berkowitz, 2006), and state/local agencies are encouraged to evaluate PAMS 

measurements and apply them to air quality modeling.

iv. Provide additional measurements of selected criteria pollutants. Such measurements can later be 

used for attainment/nonattainment decisions and to construct NAAQS maintenance plans. 

This depends on the specific needs of each region. It appears that most of the PAMS 

measurements are located at existing sites that already acquire compliance 

measurements. This objective is probably not essential. 

v. Provide additional measurements of selected criteria and non-criteria pollutants from properly-sited 

locations. Such measurements can later be used for evaluating population exposure to air toxics as 

well as criteria pollutants. 

The PAMS VOC data has aided in the interpretation of other measurements and 

provided a basis for human exposure estimates (Blanchard and Tanenbaum, 2006; 

Chinkin et al., 2003; Chung et al., 2003; Lewis et al., 1998; 1998a; Main et al., 1998b; 

Reiss, 2006; Reissell et al., 2003; Seila et al., 2001; 2002a; Sistla et al., 2002b; Sistla 

and Aleksic, 2007; U.S.EPA, 1996; Vukovich, 2000; Xie and Berkowitz, 2007). If air 

toxics are to be included as part of the PAMS objectives, the current list of 56 PAMS 

target VOCs needs to be evaluated or modified to include more air toxic species.

vi. Provide local, current meteorological and ambient data to serve as initial and boundary condition 

information for photochemical grid models. These data can later be used as a baseline for model 

evaluation and to minimize model adjustments and reliance on default settings. 

Although meteorological data are useful at any monitoring site, and can be acquired 

cost-effectively with other measurements, the surface measurements represent more 

middle- to neighborhood-scales than the larger urban- to regional-scales that are 

appropriate for photochemical assessments. Surface meteorological data and much of 

the vertical meteorological information is available from the regional climate centers 

(DRI, 2011). More information on the vertical structure, e.g., through profilers and 

acoustic sounders (Berman et al., 1997; Berman et al., 1999; Beyrich, 1997; Crescenti 

et al., 2000; Gunter, 2007; Hanna et al., 2006; Michelson and Seaman, 2000; Prabha et 
D-11

al., 2002; Reitebuch et al., 2000) would be useful, especially for O3 reservoirs aloft, 

recirculation via sea breezes, upslope/downslope flow, convergence zones and eddies, 

and low-level jets.

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time? What current objectives, if any, should be deemphasized or eliminated?

The suggestions for improving forecasting, understanding secondary organic aerosols, air toxics, 

and climate forcing substances are all good objectives. In order to make the best use of the 

existing resources, U.S. EPA should consider objectives consistent with the multipollutant/multi-effect directions for air quality management (Brook et al., 2009; Chow et al., 

2010; Dominici et al., 2010; ECOS, 2010; Greenbaum and Shaikh, 2010; Hart et al., 2011; Hidy 

and Pennell, 2010; Mauderly and Samet, 2009). 

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites? 

The four site types seem logical and comprehensive. However, the terms “upwind” and 

“downwind” are not very descriptive, as many of the O3 clouds are regional in nature (e.g., 

southeastern, northeastern, and midwestern U.S.). Less complex “satellite sites” that are portable, 

and possibly temporary (e.g., less than a year) would be useful for better defining the spatial 

extent of the attainment area (Clark County Department of Air Quality and Environmental 

Management, 2004; Seitz, 2000). Inexpensive measurement technologies are available for this 

(e.g., 2B Technologies, 2010a; 2B Technologies, 2010b; Betts, 2009; Martin et al., 2010; Mason 

et al., 2011). Flexibility on the number and types of sites should still be available to the local and 

regional air quality management districts to meet their specific needs. 

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage? 

This need not be a requirement, but some network resources should be available to local 

and regional air quality management entities that make a case for greater spatial 

coverage. For example, the fast-expanding extraction of natural gas in Wyoming and 

Pennsylvania is accompanied by increasing NOx and VOC emissions that may increase 

the O3 levels. It would be good to begin the measurement of these emissions before 

NAAQS are exceeded.
D-12

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)? 

These sites should be based on specific needs, as specified by the local or regional air quality 

managers. It is probably a good idea to consider PAMS measurements at maximum 

concentration sites in all non-attainment areas as well as those of urban NCore sites to provide 

better insights into elevated O3 phenomena.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

As noted above, this type of mobile or temporary site should be expanded. Satellite sites should 

be used to exchange some accuracy and precision for denser spatial coverage to identify hot 

spots, boundaries, and carryover phenomena. They would be inexpensive and portable with 

wireless communications. A mobile site could be configured with more complex 

instrumentation, such as the auto-GC that obtains higher time resolution continuously with 

greater number of atmospheric components for shorter monitor periods at a specific location. 

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included? 

The program must remain flexible. It should require well-reasoned plans from the air quality 

management entities for each region that propose a conceptual model for elevated 

concentrations, then justify the measurements needed to enhance or disprove that model.

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors? 

Analysis of the existing data from PAMS and other networks should be used to justify 

monitoring periods appropriate to each domain. Flexibility of monitoring periods/seasons should 

be given to the local agency to justify the needs for the region. Special studies at different 

regions during different seasons can be used to refine specific monitoring periods for each 

domain.
D-13

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list? 

It is probably a good idea for EPA to document the rationale for the selection of the current 56 

target PAMS VOCs. The following criteria need to be considered when re-evaluating the PAMS 

target list:

Compounds in VOC profiles from existing sources in the domain: needed for tracking trends 

when emissions are reduced, to identify marker species from major pollution sources and for 

secondary aerosol formation, to apportion ambient VOC to different sources for top-down 

inventory verification, and for evaluating models through comparison with ambient 

measurements (Watson et al., 2001). Carbonyls are directly emitted as well as being formed in 

the atmosphere (Ban-Weiss et al., 2008; Di et al., 2009; Guarieiro et al., 2009; Ho et al., 2006; 

Kundu et al., 2010; Muller et al., 2006) and should be included as part of the PAMS target list. 

The basic 56 PAMS species should be retained as a minimum. These VOC compounds are 

evolved from the analysis of dual-GC detector, so removing some of the target compounds from 

the current list is unlikely to achieve much cost savings on analyses, although additional 

resources may be required for data validation. Also, the sum of these species has been adopted in 

many places (not just the U.S.) to represent total hydrocarbons (Watson et al., 2001). 

Reactive O3 precursors: most of these are a subset of the emission profile compounds.

Potentially toxic substances: ideally, these should be a subset of emission profile compounds, 

since the majority of hazardous air pollutants (HAPs; http://www.epa.gov/oar/oaq-caa) selected 

for the U.S. EPA 1999 National-Scale Air Toxics Assessment (U.S. EPA, 2006) were organic 

compounds, classes, or mixtures. The Urban Air Toxics list is shown below (U.S. EPA 1999, 

2006; Table from Mauderly and Chow, 2008). Most of the 21 VOCs for the Urban Air Toxics do 

not overlap with the PAMS target VOC list. For multipollutant air quality management, the 

PAMS target list should be expanded to include air toxic VOCs

(From Mauderly and Chow, 2008)

End-products: usually more oxygenated species with lower vapor pressures that also might 

result in secondary organic aerosol formation (Miracolo et al., 2010; Presto et al., 2010; 

Robinson et al., 2007)

Compounds from the above that can be cost-effectively quantified.
D-14

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list? 

Full advantage should be taken of the acquired samples to obtain as many of the compounds as 

possible that meet the criteria stated in Question 9. Even unidentified peaks have value (Gan and 

Hopke, 2003). 

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs? 

The canisters (Batterman et al., 1998; Castellnou et al., 1998; Doezema et al., 2010; Eklund et 

al., 2004; Evans et al., 1998; Gholson et al., 1989; Heo et al., 2001; McClenny et al., 1991; 

Merrifield, 1987; Oliver et al., 1986; Plass-Dulmer et al., 2006; Schmidbauer and Oehme, 1988; 

Sin et al., 2001; Sulyok et al., 2001) are considered to be the standard method, with wellestablished procedures for quality assurance (QA) and quality control (QC). VOC canisters 

contain enough air to be submitted to many different analyses and re-analyses. Even without 

adequate temporal or spatial resolution, canister data are useful for trend analysis that meet the 

criteria listed in the response to Question 9 with low capital investment. The disadvantage of 

canisters are: 1) they are labor intensive; 2) some VOCs deteriorate with storage time; 3) reliable 

results are not available for heavier hydrocarbons above C12 – these are not so important for O3, 

but are very important for photochemical secondary organic aerosol formation (Pandis et al., 

1992); and 4) low time resolution, which is limited by the number of canisters that can be filled 

and changed.

The field auto-GCs (Altshuller et al., 1966; Bartenbach et al., 2007; Chang et al., 2010; Chung et 

al., 2003; Cisper et al., 1995; Crutzen et al., 2000; Daughtrey et al., 1998; Derwent et al., 1999; 

Farmer et al., 1994; Fujita et al., 1996; Kabir and Kim, 2010; Lu, 1996; Maris et al., 2003; Oliver 

et al., 1996; Rappenglück et al., 1998; Rappenglück and Fabian, 1999; Seila et al., 2001; Wang 

et al., 1999; Yamamoto et al., 1998; Yamamoto et al., 2000) provide hourly data (high time 

resolution) by absorbing the VOCs on a chilled substrate, then thermally releasing them into the 

GC. As compared to the infrequent sampling by canister, the auto-GC has the advantage of realtime continuous measurement to allow a better understanding of atmospheric processes and 

pollution formation, and can be used for source identification by receptor modeling. The autoGC can be operated year-round, which minimizes the controversy created by the limitations of 

canisters to specific time periods or seasons. The disadvantages of the auto-GC include: 1) not all 

of the VOCs are efficiently collected on the substrate by auto-GC; 2) a high capital investment is 

required, including trained field technicians to operate and maintain the instrument and a trained 

chemist to validate the hourly data (QA/QC; i.e., standards calibration), which can be labor 

intensive; and 3) the compounds measured are less comprehensive than those obtained from the 

canisters through laboratory analysis. More collocated comparisons between canister and field 

auto-GC should be conducted at different types of PAMS sites during different seasons to 

establish the equivalence and comparability between the two approaches.
D-15

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network? 

Several commercial pre-concentration and GC analysis units are available (AMA Instruments, 

2011; Broadway and Tipler, 2009; Ecotech, 2011; SRI Instruments, 2011; Synspec, 2011a; 

Synspec, 2011b; Synspec, 2011c), but they are poorly documented for the most part. Several of 

them require two collocated instruments to obtain the low and high C-number compounds. 

Broadway and Tipler (2009) describe the latest incarnation of the Perkin Elmer ATD400 

Automatic Thermal Desorption unit that was used as several of the PAMS sites. The XonTech 

Model 930 (Oliver et al., 1996) appears to have also been used at some locations, especially in 

California. Comprehensive descriptions of each available unit, better than that on the 

manufacturer’s websites, need to be assembled that would include an instrument description, 

compounds measured, minimum detection limits, reproducibility, power and space requirements, 

purchase costs, operating supplies (i.e., gases, absorbents, spare parts), and standard operating 

procedures. A subset of available units should be obtained and compared, using prior VOC 

comparison studies (Apel et al., 1994; Apel et al., 1998; Apel et al., 2003; Apel and Calvert, 

1994; Chang et al., 2010; Durana et al., 2002; Fujita et al., 1994; Fujita et al., 2003; Gurka, 1984; 

Kuster et al., 2004; Liikala et al., 1996; Lonneman et al., 1989; Maris et al., 2003; McClenny et 

al., 1985; Rappengluck et al., 2006; Schmidbauer and Oehme, 1988; Shreffler, 1993; Sistla and 

Aleksic, 2007; Tang et al., 2006) as a guide for methods and performance. This information can 

then serve as a basis to evaluate the appropriateness of commercially available auto-GCs for use 

at PAMS sites.

It would be worthwhile to update the field auto-GC requirements in U.S. EPA (1998). 

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program? 

The definition of total non-methane hydrocarbons (TNMH) and how it should be measured 

needs to be clarified. TNMH is useful to bound the hydrocarbon content, provide better time 

resolution, and for certain observational models (Cardelino and Chameides, 2000).

Charge Question 14: Should carbonyls be required at all VOC speciation sites? 

Carbonyls are important primary emittants and photochemical end-products. As more renewable 

fuels are added to gasoline and diesel (Correa and Arbilla, 2008; Di et al., 2009; Guarieiro et al., 

2009; Lin et al., 2009; Liu et al., 2009b; Pang et al., 2006; Pang et al., 2008; Peng et al., 2008; 

Tanner et al., 1988; Yuan et al., 2009), there may be changes in their ambient concentrations that 

should be tracked. 
D-16

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

The major issues with DNPH sampling and analysis for carbonyls are: incomplete collection, 

losses due to chemical reactions (e.g. with O3), creation of new carbonyls as additional pollutants 

are pulled through the DNPH cartridge, and contamination. These biases can be minimized 

through appropriate precautions, established standard operating procedures, and enhanced 

QA/QC measures (Dillon and Gao, 1994; Ho et al., 2011; Kleindienst et al., 1998; Lee et al., 

2006; Lee and Zhou, 1993). 

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling? 

Batterman et al. (1998) didn’t have much success obtaining accurate concentrations of butanal, 

pentanal, hexanal, heptanal, octanal, nonanal and benzaldehyde from stainless steel canisters. 

They found ~18 day half-lives for aldehydes in humidified air-filled canisters; half –lives were 

~6 days for dry air. Better results have been found for certain carbonyls collected on Tenax and 

analyzed by thermal desorption (Ho and Yu, 2004; Kim and Pal, 2010; Lee et al., 2006). To 

consider alternate methods to the manual TO-11A method, a comparison study should be 

conducted to evaluate the pros and cons of the different methods for carbonyl speciation.

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment 

in the PAMS network? What additional evaluations are necessary to determine the suitability for use in 

the PAMS network? 

Currently, NO2 is required at Type 2 (maximum emission) sites, where NOy has been measured 

at Type 1 (upwind) and Type 3 (maximum O3) sites since 2006.

Several photolytic and cavity ringdown systems are commercially available (Aerodyne Research 

Inc., 2011; Air Quality Design, 2011; EcoPhysics, 2011; Los Gatos Research, 2011) that require 

further evaluation. There is ample evidence (Dunlea et al., 2007; Steinbacher et al., 2007; Winer 

et al., 1974) that NO2 is overestimated by FRM monitors that use a catalyst to convert NO2 and 

other compounds (e.g., PAN, HNO3, PM nitrate) to NO, especially in rural and remote locations 

where NOx may not be the dominant species in NOy. Ammonium nitrate collected on a pre-filter 

at cooler temperatures can convert to HNO3 during warmer parts of the day, thereby increasing 

the apparent NO2 (Chow et al., 1994; Chow et al., 2002; Chow et al., 2005). Photolytic 

converters (Castellanos et al., 2009; Gao et al., 1994; Kley and McFarland, 1980; Nakamura et 

al., 2003; Ryerson et al., 2000; Thornton et al., 2003) use ultraviolet light to transform NO2 to 

NO. Reported converter efficiencies range from 40% to 90%, and the conversion stability is not 

reported. Some researchers use intense light sources that heat the sample, which may cause some 

changes in equilibrium (e.g., PAN to NO2). The cavity ringdown instruments (Castellanos et al., 

2009; Fuchs et al., 2009; Osthoff et al., 2006) appear to be most specific to NO2. Luminol 

detectors (Gaffney et al., 1999; Kelly et al., 1990) separate PAN from NO2, but they tend to be 

messy and unreliable. 
D-17

As with the field auto-GCs, available NO2 monitors need to be field compared at different 

environments during different seasons. They should be described with minimum detection limits, 

reproducibility, power and space requirements, purchase costs, operating supplies, and standard 

operating procedures. Previous comparison studies (Dunlea et al., 2007; Fehsenfeld et al., 1990; 

Goyal and Gavane, 2005; Gregory et al., 1990; Mackay et al., 1988; Nakamura et al., 2003; 

Osthoff et al., 2006; Steinbacher et al., 2007; Thornton et al., 2003; Vaughan et al., 1997; Zenker 

et al., 1998) can be used as a guide for methodology and expected tolerances.

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations? 

Satellite detection is a useful adjunct, but the spatial scale (~10 km) and temporal resolution 

(often once or twice per day) is insufficient for many photochemical episodes and spatial scales 

(Fishman et al., 2002; Hidy et al., 2009; Hoff and Christopher, 2009; Liu et al., 2009a; Martin, 

2008). Unmanned aerial vehicles with microsensors (Char et al., 2010; Ogren and Winstrand, 

2008; Pereira et al., 2009; Sitnikov et al., 2005; Spiess et al., 2007) represent an emerging 

technology that has yet to be exploited. Tethered balloon-borne sondes (Schnitzhofer et al., 2009; 

Thompson et al., 2007a; Thompson et al., 2007b; Wohrnschimmel et al., 2006; Worden et al., 

2007) have also proven useful.

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data a

PAMS sites? 

Yes. Vertical structures of wind data provide additional information about atmospheric transport 

phenomena. Note comment related to Question 1. These measurements should be based on a 

conceptual framework of upper air transport, carryover, and recirculation. 

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

It is a good idea to include NOAA meteorological data into the PAMS program, and use it as 

much as possible. As noted in the response to Question 1, NOAA’s climate centers are an 

efficient source of meteorological data. 

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted? 

Analysis for PAMS data should include: trend analyses, source apportionment to verify emission 

inventories and target emission reductions, observational models to determine NOx/VOC 

inflections, model input for initial and boundary conditions, and model ground-truthing.
D-18

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level? 

Some of the resources should be reserved for specific data analysis projects. As noted in the 

response to Question 1, a better data base is needed to make the data easier to obtain and use. It 

should be used by anyone who wants to use it. The number of published articles and reports for 

the PAMS network are only about 10–15% of those using data from the IMPROVE network. 

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis? 

A greater number of quality reports and peer reviewed publications should be expected if 25% of 

the PAMS fund is to be used for data analysis. It doesn’t seem that any resources are allocated to 

method characterization and data analyses. The PAMS websites aren’t even kept up to date, as

noted in the response to Question 1.

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Comments from Dr. Kenneth Demerjian

The CASAC AMMS Panel is requested to respond to the following charge questions in regard to 

monitoring topics related to PAMS Network Re-engineering.

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any should be deemphasized or eliminated?

The program objectives identified in the current whitepaper over lap and are not concise. PAMS design 

objectives must be identified along with specified analyses to be performed to meet those objectives, for 

example;

The PAMS VOC measurements should be applied to:

1) Track and verify that trends in species specific VOCs are consistent with VOC mitigation 

emission strategies and target controls (e.g. assess VOC trends in response to: 1) to phase 1& 

2 RFG (with specific look at catalytic convertor performance in response to Tier 2 gasoline 

sulfur control and mobile source air toxic MSAT controls; 2) introduction of low sulfur 

diesel fuel; 3) 2007 diesel emission emissions standard; 4) the economic recession; and 

5)introduction of renewable fuels.

2) Provide compound specific diurnal patterns to evaluate emission profiles (as specified in 

emissions models by source) and for evaluation of the air quality modeling system overall 

(e.g., see Doraiswamy et al., 2009 and Ren et al.,2003, Ren et al., 2006). 

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

See above.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

The spatial distribution of the current PAMS design was envisioned to capture the upwind, urban central 

and downwind concentrations of VOCs. These data were intended to support model evaluations and 

improve diagnostic evaluation of ozone’s response to VOC concentration perturbations from high 

density urban emissions. Continuous (hourly measurements) at central urban sites should remain as the 

foundation for the network. Upwind inflow sites should be restricted to regions with specific interstate 

transport issues (e.g. NE corridor or enhanced biogenic influence such as Atlanta).
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Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

Yes – measurements at some NCore sites (see next question) and at some rural sites to help assess 

background VOC’s contribution to policy relevant background O3.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites) ?

EPA should consider PAMS measurements at a subset of regional oriented NCORE sites to characterize 

the composition of aged anthropogenic VOCs and biogenic VOC content to assess their contribution to 

regional ozone production and secondary organic aerosol production.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

Mobile or temporary sites can be deployed to characterize spatial distribution of VOCs in the vicinity of 

unique industrial sources (chemical or refinery operations) or where intrastate transport is occurring 

between major metropolitan areas.

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included?

Without knowing the specifics of the “very flexible program” it is impossible to make informed 

comments. But, it would seem that providing a framework for States to consider when addressing their 

targeted issues would be appropriate. The framework would, for example, identify operational 

flexibilities with respect to the needs for national data sets as well as methodological measurement 

options and the utility of special study deployments. That being said, my experience has been that states 

typically are quite knowledgeable when it comes to their measurement needs. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

The current PAMS monitoring season framework should be determined on a case-by case basis with the 

intent to shorten the measurement period (and reduce cost). A variety of analysis techniques using 

ambient air quality and meteorological data are available.

PAMS measurements during the non-photochemical season should be considered on a special studies 

basis. Previous studies suggest possible flaws in our understanding of winter-time chemistry (Ren et al, 

2006) and may also have implications on secondary aerosol production.
D-35

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list?

In developing the target VOC list, consideration should be given to site characterization (i.e., urban or 

regional) and the following overall compound specific criteria: 

The VOC is good marker for specific emission sources;

The VOC is a precursor of or is urban air toxic;

The VOC’s reactivity (high ozone forming potential)

The VOC’s secondary organic forming potential

The VOC is above LOD 30% or more of the time 

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

Consider adding one or more biogenic VOCs that are representative of the “terpene class of compounds” 

This is easier said than done.

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

Field deployed auto-GCs provide diurnal concentrations (not possible with 24-hr avg. canister) that are 

particularly useful in evaluating air quality models and performing diagnostic emission attribution 

studies.

Manual canisters can play a role in supporting annual trend analyses of VOCs and tracking the 

effectiveness of specific emission control programs.

A cost analysis should be performed comparing the autoGC and canister approaches, given the PAMS 

measurement objectives to be addressed. Consideration might be given to a hybrid approach.

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

There is limited state experience with new commercially available dual column dual detector auto-GCs 

provide. These systems need to be evaluated against traditional canister analyses and standard 1st

generation auto-GCs via side-by-side comparisons would be useful. 

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

There are important reasons to quantify the magnitude of unidentified hydrocarbons in the atmosphere. 

The PAMS unidentified compounds which appear as an unresolved peak on the auto- GC column as a 

result of the temperature purge at the end of the 40-min temperature program representative of high 

molecular weight compounds (i.e. >C10) which likely contribute to local/regional ozone production and 

to local secondary organic aerosol production. TNMH serves to quantify an additional increment of 

unidentified hydrocarbon in the atmosphere which is determined from the difference between TNMHPAMSTotalHC.
D-36

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

Carbonyl measurements should be considered on a special studies basis with specific objectives and 

advanced measurement technologies. (e.g., traffic related formaldehyde concentration exposure; 

gasoline and diesel on-road direct emission measurements of formaldehyde; and photochemical 

production of secondary formaldehyde in urban and regional environments. These applications would 

deploy advanced fast response measurement technologies to monitor atmospheric formaldehyde (e.g. 

tunable laser IR absorption spectroscopy or differential optical absorption spectroscopy). 

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling?

Under strategic special study deployment consider differential optical absorption spectroscopy, DOAS; 

tunable laser IR absorption spectroscopy. 

Charge Question 17: Are direct measurement NO2 or photolytic analyzers suitable for deployment in 

the PAMS network? What additional evaluations are necessary to determine their suitability for use in 

the PAMS network?

Yes - direct measurement NO2 or photolytic analyzers are suitable for deployment in the PAMS 

network. These measurements can be phased in and inter-compared with traditional NOx boxes prior to 

phasing out the NOx boxes.

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations?

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites?

If these data are available from a NWS surface met observation site that is regionally representative, 

these data should be acquired and made part of the data set.

Charge Question 20: How should NOAA data be incorporated into the PAMS program? 

NOAA/NWS met data should be incorporated into the PAMS data base on an hourly average basis 

similar to that for the current PAMS met measurement parameters. 
D-37

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted? 

Diurnal patterns of specific marker VOCs; see figure 1 below

Annual trends of specific marker VOCs; see figure 2 below

Estimate of SOA production potential; see figure 3 below

Estimate VOC reactivity index and O3 production potential.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level? 

Each organization has a role to play and vested interest in the analyses and interpretation of results. 

Independent funding should be considered for competitive solicitations to explore diagnostic analyses 

approaches to address process science and policy relevant objectives. 

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis? 

The PAMS analysis budget of 25% of total expenditures is reasonable, if properly allocated. EPA might 

consider setting aside a portion (15% of the PAMS analyses funds) to support independent scientists to 

develop diagnostic approaches, as mentioned above, to address process science and policy relevant 

objectives.

References

Doraiswamy, P., C. Hogrefe, W. Hao, R.F. Henry, K. Civerolo, J.K. Ku, G. Sistla, J.J. Schwab, K.L. 

Demerjian, 2009. A diagnostic comparison of measured and model-predicted speciated VOC 

concentrations, Atmospheric Environment 43, 5759-5770.

Ren, X., W.H. Brune, J. M., M. J. Mitchell, R.L. Lesher, A.R. Metcalf, J. B. Simpas, J. J. Schwab, K. L. 

Demerjian, H.D. Felton, G. Boynton, Y. He, X. Zhou, and J. Hou, 2006. Behavior of OH and HO2 in the 

Winter Atmosphere in New York City, Atmospheric Environment, 40, S252-S263.

Ren X., H. Harder, M. Martinez, R.L. Lesher, A. Oliger, J.B. Simpas, W.H. Brune, J.J. Schwab, K.L. 

Demerjian, Y. He, X. Zhou and H.Gao, OH and HO2 chemistry in the urban atmosphere of New York 

City, Atmospheric Environment, 37, 3639-3651, 2003
D-38

Figures:

Isopentane Diurnal NYBG 1995 vs. 2009

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

10

20

30

40

Isopentane (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

10

20

30

40

Isopentane (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

10

20

30

40

Isopentane (NYBG, 2009), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

10

20

30

40 Isopentane (NYBG, 2009), ppbC

ethene diurnal NYBG 1995 vs. 2009

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

6

12

18

24

ethene (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

6

12

18

24 ethene (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

6

12

18

24

ethene, (2009, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

6

12

18

24

ethene, (2009, NYBG), ppbC

NYBG Isopentane Trend

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Year

0

2

4

6

8

10

Isopentane.ppbC

1226- 0.6094*x

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Year

0

2

4

6

8

10 Isopentane.ppbC

1226- 0.6094*x

~ - 5.8% /yr

NYBG n-decane Trend

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Year

0.0

0.5

1.0

1.5

2.0

2.5

n-decane, ppbC

288.6- 0.1435*x

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Year

0.0

0.5

1.0

1.5

2.0

2.5 n-decane, ppbC

288.6- 0.1435*x

~ - 5.7% /yr

NYBG Benzene Trend

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

year

1.0

1.5

2.0

2.5

3.0

3.5

benzene.ppbC

134.1- 0.066*x

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

year

1.0

1.5

2.0

2.5

3.0

3.5 benzene.ppbC

134.1- 0.066*x

~ - 2.6% /yr

n-decane diurnal NYBG 1995 vs. 2009

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

2

4

6

8

n-decane (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Hour

0

2

4

6

8

n-decane (1995, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

2

4

6

8

n-decane (2009, NYBG), ppbC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

hour

0

2

4

6

8n-decane (2009, NYBG), ppbC
D-39

Comments from Mr. Dirk Felton

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated?

The most important priorities in the current program are to provide a speciated VOC database for 

photochemical modeling and for evaluation of the emissions inventory. Neither of these objectives is 

currently being met. The photochemical grid models utilize VOCs by functional group which are not 

provided by the PAMs program and the source emissions impact cannot be evaluated because the 

emissions inventory is not VOC specific. The EPA should move towards a harmonization of the overall 

approach from emission inventory through ambient data collection and atmospheric model 

demonstration. All of these elements need to be consistent with each other for the system to work 

cohesively. 

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

The existing PAMs network design favors urban areas which had been designated as severe for the 1-Hr 

Ozone standard. The PAMs objectives should be expanded to include data collection in support of 

research to determine the significance of regional background Ozone in relation to locally produced and 

transported anthropogenic Ozone. This research should include an identification of natural biogenic 

precursors that are not subject to mitigation strategies as well as biogenic precursors resulting from 

anthropogenic activities such as agricultural and livestock operations.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

The concept of a PAMs area has to be reconsidered. The implementation of targeted control strategies 

that were designed to reduce the local 1-Hr exceedences has been effective. This, in combination with 

the longer 8-Hr average form of the standard has resulted in monitors that exceed the standard by a 

smaller margin but these exceedences are now occurring over much larger areas. This means that the 

criteria that defines a Type 1 and Type 2 site are becoming less distinct. In some areas, the upwind 

Ozone monitors are non-attainment. It would be better to define Ozone production regions based on the 

source categories that are prevalent in each of these areas.

Once an Ozone production region is defined, the monitoring needs for that region can be determined and 

a monitoring and data analysis plan can be implemented. The plan must be tailored to the specific source 

categories including mobile sources, industrial, agricultural, power sector, biogenic and meteorology 

that contribute to the Ozone problem in that region. Special studies and analysis projects can then be 

designed as gaps are discovered in the knowledge base for each area. This should be more effective than 

the current design which emphasizes Type 1 sites which often are not really background, redundant type 

2 monitors and Type 3 and 4 sites which are less helpful for control strategy development.

All of the sites must be designed to be neighborhood scale or larger. Ozone is a regional problem and 

solutions that are designed to control a micro-scale problem will not be effective. The exception to this 
D-40

is a special purpose monitor installed to perform source characterization that can be utilized to determine 

the influence of multiple similar sources over a wide area.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

Yes, there are areas of the country where the moderate classification could be more or less intractable 

depending on where the level of the standard is set. These areas are often geographically distinct from 

the existing PAMs areas which at one time had been classified as serious. PAMs measurements may be 

needed in order to determine the precursor mix as well as potential control strategies for these 

geographically distinct moderate areas.

It may not be necessary to add PAMs measurements to areas classified as moderate if they are adjacent 

to areas where PAMs measurements are already implemented. These moderate areas will likely respond 

to whatever control strategies are implemented for the adjacent area where the Ozone problem is more 

significant.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)?

The PAMs program needs to be flexible enough to permit new sites and specific monitoring parameters 

where they are needed. In some areas, NOx monitoring might be more effective than VOC or Carbonyl 

measurements.

Requiring monitoring for specific parameters where it will not be helpful should not be part of the 

program.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

The PAMs program should be flexible enough to permit short-term monitoring to help define the aerial 

extent of the impact of source categories. This is the kind of information necessary to develop viable 

control strategies. One thing that has been demonstrated by the existing PAMs VOC dataset is that the 

VOC fingerprint for a particular region tends to remain consistent even as the overall concentrations rise 

and fall. It may be possible to reduce the number of Type 2 sites and use short-term, mobile or other 

unconventional monitoring to help expand the geographic representativeness of the PAMs 

measurements. 
D-41

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included?

The PAMs program needs the ability to support research needs for Ozone problems that vary regionally 

due to precursor composition, meteorology and available, viable control strategies. Biogenic precursors 

for instance, don’t lend themselves to viable control strategies so a PAMs program targeting a region 

heavily impacted by biogenic VOCs may need to obtain detailed information on NOx, upper air 

meteorology or another parameter that will help in the formulation of a successful control strategy.

The PAMs program should not be classified as a monitoring program. This is too rigid a structure to be 

effective in dealing with the Nation’s Ozone problem. The PAMs program needs to become a resource 

with a number of monitoring and data collection options with a significant portion of resources set aside 

for special studies and data analysis. Program requirements should be reduced to the extent possible 

while recognizing the value of keeping enough of the traditional Type 2 sites for trends analysis. The 

EPA should, however, make the methods used for monitoring as uniform as possible so the data can be 

useful for comparisons from one Ozone research area to another. Some of the PAMs program categories 

should include:

Category 1: Monitoring and Data Collection 

• Trend: 1-Hr VOC using Field GC, auto-system or newer alternative

• Trend: 3-Hr or 24-Hr Carbonyl

• NOx, NOy, TNMOC and Trace CO

• Additional Ozone monitoring (upwind, high altitude, off-shore)

• Upper air Meteorology: (Profiler, Ceilometer, Vertical temperature) 

• Solar radiation (Visible/UV/multiband)

Category 2: Special Studies:

• Short-term precursor/Ozone studies (spatial, elevation and temporal)

Mobile GC, temporary site (up to 1-Yr) or canister deployment,

Canister collected by threshold from TNMHC analyzer

• Emission/source characterization: (stack test, Biogenic flux measurements, etc.) 

• OH measurements in Ozone production regions

• Continuous Carbonyl

• Evaluation of newer GCs without Nafion dryers

• Evaluation of NO2 methods

Category 3: Data Analysis Studies:

• Atmospheric Chemistry investigation

• Model sensitivity, boundary studies

• Model development: individual VOC reaction rates

The efficient implementation of a more flexible PAMs program could be problematic because States 

can’t effectively institute the program on their own if a needed monitoring or special study effort has to 

take place in an up or downwind State or Country. To help make the PAMs program as useful as 
D-42

possible, the selection of monitoring parameters and data analysis objectives must be made on a 

multistate, regional basis. It would be helpful if the RPO model was re-instituted to help coordinate this 

effort.

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

The PAMs monitoring season must at a minimum cover the period for the local Ozone season. There is 

no guarantee that a mitigation strategy that works for an August exceedence will also work for one that 

occurs in March. It would be helpful if at least one Type 2 site in each Ozone Region operated yearround. The data will improve the understanding of patterns of emissions and could provide useful air 

toxics data. 

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list?

This question is difficult to answer due to the large percentage of unknown compounds that cannot be 

measured with the current Auto-GCs. The newer compact field GC’s that do not have a Nafion dryer 

may be able to resolve some of these compounds. The target list should be relatively flexible so species 

can be added if tracers are found for source categories. It is also likely different target lists will be 

appropriate for different areas. The VOCs and NOx species prevalent in industrial cities will vary from 

those found in the Northeast or the Southwest or in rural areas. 

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

The EPA should try to identify more compounds that can be used to characterize emissions sources 

including biogenics. 

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

The hourly Auto-system data is more appropriate for model evaluation due to the diurnal profile of data.

The canister data can be used to quality assure the auto-system data and to expand the geographic 

representativeness of the auto-system data.

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

EPA ORD should conduct a 1-Yr side by side comparison of the auto-system with the newer compact 

field GCs. This comparison should be conducted in an east coast city, a west coast city and in a rural 
D-43

area. The study should include an evaluation of the data, the ability of each method to identify 

compounds currently listed as unknown, as well as each instrument’s robustness and the necessary level 

of operator training.

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

The TNMH monitors are relatively inexpensive and are particularly useful for investigating the patterns 

of overall VOCs emissions. Since the data from these instruments are not speciated, the data are most 

useful in areas where the VOCs are already well characterized such as near existing Type 2 sites or near 

specific industrial facilities.

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

The method needs improvement. The collection efficiency, susceptibility to humidity and Ozone and 

field quality assurance procedures are all areas that must be addressed. The field samplers have not been 

part of the PAMs program’s quality assurance procedures. At a minimum, the quality assurance 

procedures should include quarterly flow audits and requirements for the preparation, heating set point 

and replacement interval for the sampler denuder.

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling?

The newer technology methods are not suitable for routine use but certainly could be part of a special 

study. The TDL and wet chemical methods could be employed where high frequency data are needed. 

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment 

in the PAMS network? What additional evaluations are necessary to determine the suitability for use in 

the PAMS network?

NO2 is important for the PAMs program but this is complicated by the need for NOy as well. A solution 

for routine operation should include a modification of the existing instrumentation that could provide 

NO, NO2 and NOy. For non-routine special studies, the TDL or the ring down spectrometer could be 

used where accurate high frequency data are required.

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations?
D-44

The regional nature of Ozone including Ozone’s precursors and the atmospheric conditions that 

contribute to Ozone formation make Ozone a better candidate for non-traditional monitoring approaches 

than other typically primary pollutants. Observational approaches are particularly well suited for 

determining the atmospheric conditions for forming Ozone. Solar radiation, temperature, mixing height, 

snow cover/reflectivity/cloud, land use and fog cover are all parameters that are well suited to vertical or 

remote measurement techniques. These measurements require little ground-truthing and should be 

automated to the extent possible using existing satellite, airport and aircraft measurement platforms.

Profilers are almost too expensive to be a routine part of the PAMs program. The EPA should consider 

the newer less expensive vertical temperature based radiometers/ceilometers that can provide mixing 

height data. This information is needed particularly in mountain regions and in places such as coastal 

regions where atmospheric models have difficulty in determining the hour to hour mixing height.

Accurate mixing height data can also make the interpretation of vertical column data more 

straightforward. 

Remote sensing techniques can also be useful for source characterization for area wide sources such as 

marine and airports, railyards, and large industrial facilities. Some of the more expensive of these such 

as FTIR, DOAS and DIAL could be utilized in the special study category of PAMs to assess 

unconventional sources.

Surface based measurements made below and above the mixing height such as at the base and summit of 

a mountain are very effective at evaluating vertical column data. The surface sites should at a minimum 

include the species that tend to remain close to the ground. 

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites?

Not all PAMs sites require upper air measurements. It would be useful to have at least one in each 

region with additional locations where the models have difficulty such as in mountain regions and near 

the marine boundary. Ceilometers may be adequate in coastal regions.

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted?

Data analysis should be tailored to each region so requiring specific data analyses may be counterproductive. The EPA should make the data easily accessible which would encourage its use by the 

outside community.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

It is difficult to implement a viable research program and control strategy development initiative within 

the boundaries of one state in a larger Ozone region such as the northeast corridor. It makes sense to use 
D-45

the RPO model to organize and direct the multi-state research effort towards a workable goal. This may 

not apply to States which encompass the Ozone area such as California and Texas.

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis?

This is an issue that should be discussed with NACAA. They will be able to weigh the opinions of the 

respective State and Local Agencies. It would not be appropriate for the EPA to take these funds without 

the consent of the Agencies that ultimately have to submit an approvable SIP.
D-46

Comments from Dr. Phil Fine

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated?

All the current PAMS objectives listed in the white paper still express valid and important needs towards 

a better understanding of ozone chemistry, transport, modeling, and attainment demonstration. The 

prioritization of these objectives, however, will be region or air shed specific. Different non-attainment 

areas will have different outstanding questions to be answered, whether it is more VOC data and trends, 

or inventory uncertainties, or background conditions, or upper air meteorology. Any attempt to prioritize 

objectives on a national level would be ignoring these regional differences. A one-size-fits-all approach 

would lead to unnecessary measurements and thus a potential waste of resources. 

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

Issues such as continental background, biogenic VOC emissions, and interstate transport are critical. So 

an objective recognizing the need for a better understanding of natural vs. anthropogenic ozone 

precursor emissions and transport from upwind or off-shore areas beyond a State’s authority to 

implement controls would be appropriate.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

The general framework of the PAMS Type 1-4 sites is scientifically sound, but as mentioned in the 

white paper and implemented in recent PAMS program changes, different ozone non-attainment areas 

will have different needs, and a high priority site may not fit perfectly into one of the PAMS site type 

categories. There may also be some overlap of Type 4 sites in one area and Type 1 sites in the 

neighboring area that may cause redundancies.

The advantage of this approach is to provide regulatory assurances, beyond mere guidance, to PAMS 

agencies as to the important criteria in choosing a set of PAMS sites. This can also be considered a 

disadvantage if it causes a lack of flexibility to site PAMS stations where state and local agencies feel 

they need to site them. The number of sites and spatial distribution within a state or region may also be 

better determined by local needs. If a better national distribution is desired for VOC precursors, then 

perhaps other programs not tied to ozone attainment status, such as NCore or NATTS, would be better 

suited to provide that coverage. 

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

As stated above, if a better national distribution is desired for VOC precursors, then perhaps other 

programs not tied to ozone attainment status, such as NCore or NATTS, would be better suited to 

provide that coverage. Lowering the ozone status threshold for PAMS to below serious would likely 

lead to too numerous and often unnecessary measurement sites. 
D-47

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)?

The answer should depend on both the local data needs as well as the desire for national spatial 

coverage. Dictating that every ozone non-attainment area implement PAMS measurements may not be a 

wise allocation of resources if those areas on the edge of attainment understand the problem and/or are 

expected to be in attainment as control programs take effect. Perhaps PAMs measurements could be 

optional in some of these areas. However, the NCore and NATTS could provide the desired national 

coverage and consistency while limiting the resource requirements. 

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

If a state or local agency can develop a sampling plan utilizing such an approach that would help to 

address their particular ozone issues, then this approach may be useful and should be supported. But 

given the complexity in deploying this type of monitoring, there should be no national-level 

requirements for mobile or temporary sites.

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included?

Flexibility will be key to a successful PAMS program that meets the stated objectives in the most 

efficient way. There are advantages to a highly specified program, such as national consistency in 

methods and ensuring spatial coverage for national assessments and modeling efforts. However, there is 

a lot of room in the current PAMS requirements to relax some requirements while still achieving these 

national-level goals. Current sampling requirements for sub-daily periods, frequencies, and seasons may 

result in many more samples (and resources expended) than is really needed to achieve both local and 

national goals. Resources saved by relaxing these requirements could be put towards other monitoring 

more relevant to local needs. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

The PAMS monitoring seasons should be determined on a case-by-case basis based on local factors such 

as those listed (ambient data, meteorology, climatology), but also based on other local needs such as 

model evaluation and inventory checks. If there exists a need to perform these measurements year round 

to fully evaluate models and inventories, then it should be supported within the PAMS framework. 

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list?

The EPA should continue to look at historical data regarding ambient levels, and eliminate compounds 

that are rarely found above detection limits. This may have to be done on a regional basis. The EPA 
D-48

should also consider what is known about reactivity of the VOCs, and possibly develop a reactivity 

weighted index to help further reduce the size of the target list. The EPA should not preclude the 

measurement or reporting of VOCs not on a smaller target list if the local agency has a specific need to 

measure that VOC. Adding in additional biogenic VOCs, given their abundance in certain areas and 

their reactivity, is recommended. 

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

In general the target list should be greatly reduced or even eliminated entirely, and allow the state and 

local monitoring agencies to develop a target list based on their needs. As stated above any VOC that is 

mostly below detection or has a low reactivity weighted importance for ozone production should be 

eliminated. The known biogenic and reactive VOCs such as mono-terpenes should be added. Carbonyls 

should be retained if a full assessment of the sampling and analytical issues shows the data to be 

reliable. 

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

If a field deployed auto-GC is a reliable, robust, instrument that can run continuously with minimal field 

staff time, then there can be considerable resource savings. However, this is rarely the case with current 

instrumentation, and the fact that they provide hourly data leads to the need for extra staff resources in 

fully validating this much larger data set. The extra value in hourly vs. 3-hour samples is questionable. 

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

A full evaluation of these new auto-GCs is highly recommended, not just for accuracy, precision, 

specificity, and target analyte capabilities, but also for ease of deployment, reliability, robustness, and 

cost of operation. If these new instruments can be shown to perform well given these criteria, then they 

should be considered for deployment at PAMS sites.

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program? 

TNMH analyzers may have a role and their utility to meet local PAMS objectives should be determined 

by the state or local PAMS agency.

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

To the extent that the methods can be evaluated and shown to be reliable, then they should be part of the 

PAMs program. They are a very important part of ozone chemistry almost everywhere. However, 

whether or not they should be required should depend on the local ozone problem and whether there is a 

need for that specific data in that specific area.
D-49

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

Many of the issues related to TO-11A have not been addressed, such as breakthrough, low precision 

levels, reactions occurring during sampling (i.e. ozone interferences), and the accuracy of formaldehyde 

measurements. A full assessment of all PAMS carbonyl measurements taken to data, along with 

comparisons to other programs such as NATTS, should yield important information on lab-to-lab and 

sampler-to-sampler biases.

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling? 

Canister methods such as TO-15 should be re-examined for some of the carbonyls, and perhaps some of 

the field auto-GCs are better suited for carbonyl analysis vs. the traditional lab-based GCs.

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment 

in the PAMS network? What additional evaluations are necessary to determine the suitability for use in 

the PAMS network?

They may be suitable if a particular area has a need for true NO2 readings. Further evaluations 

comparing NO2 to traditional NO/NOx and NO/NOy may be necessary before wide-scale deployment.

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations?

All approaches and technologies should be considered and may be appropriate for PAMS assessments in 

specific areas. The state or local agency should propose and justify the need for such approaches to be 

funded under the PAMS program. National requirements for the use of such approaches would probably 

not be appropriate given their limited availability in some areas 

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites?

The necessity, frequency, and spatial coverage of such measurements are completely dictated by local 

modeling needs. National requirements are not warranted, but the PAMs program should support such 

efforts if justified by state and local agencies that have the need for upper air data.

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

If available and applicable, NOAA data should be considered for use by state and local agencies in 

testing and improving model performance.
D-50

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted?

The PAMS data is useful for most of the stated PAMS objectives, including trend analysis, model 

evaluation, inventory validation, and determining background conditions for the models. Specific data 

analysis efforts will depend upon the specific objective of the effort. PAMS databases should be 

considered a resource to be used as needed to answer specific questions. Less focused, routine analyses 

of PAMS data may only be useful for national or local trends assessments or for identifying biases 

dependant on sample type or laboratory.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

Local, state or regional analyses should be conducted as needed to answer specific questions related to 

ozone formation and attainment demonstration. There is little need for a national program dictating the 

types or frequency of analyses to be conducted. Routine analyses can be performed at a national level to 

examine trends or any analytical or sampling biases. 

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis?

No PAMS funding needs to be specifically allocated to data analysis. There is no need to perform some 

of these analyses annually, so allocating a fraction of funding every year would not be productive. State 

and local agencies should justify the configuration and utility of their PAMS programs, and part of that 

justification will necessarily be how the data will be used, what analyses will be conducted, and how 

much funding will be needed for those analyses.

Additional Comment

An important potential part of the PAMS program may be additional ozone and NOx measurements to 

provide spatial resolution beyond the EPA minimum monitoring requirements for PAMS or those 

criteria pollutants. It is one of the stated PAMS objectives, but was not part of the Charge Questions. If a 

state or local agencies believe a larger network of these criteria pollutants will help address their 

understanding of their particular ozone issues, then such efforts should be specifically supported by the 

PAMs program.
D-51

Comments from Dr. Phil Hopke

Charge Question 1: How should EPA prioritize the current PAMS objectives?

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time? What current objectives, if any, should be deemphasized or eliminated?

These questions are probably best answered collectively. The current objectives are 

1. Provide a speciated ambient air database which is both representative and useful for ascertaining 

ambient profiles and distinguishing among various individual VOC. These data can later be used as 

evaluation tools for control strategies, cost-effectiveness, and for understanding the mechanisms of 

pollutant transport. 

2. Provide local, current meteorological and ambient data to serve as initial and boundary condition 

information for photochemical grid models. These data can later be used as a baseline for model 

evaluation and to minimize model adjustments and reliance on default settings. 

3. Provide a representative, speciated ambient air database which is characteristic of source emission 

impacts. These data can be particularly useful in analyzing emissions inventory issues and 

corroborating progress toward attainment. 

4. Provide ambient data measurements which would allow later preparation of unadjusted and adjusted 

pollutant trends reports. 

5. Provide additional measurements of selected criteria pollutants. Such measurements can later be used 

for attainment/nonattainment decisions and to construct NAAQS maintenance plans. 

6. Provide additional measurements of selected criteria and non-criteria pollutants from properly-sited 

locations. Such measurements can later be used for evaluating population exposure to air toxics as 

well as criteria pollutants. 

These objectives are uniformly simplistic in the context of an oxidative atmosphere of varying capacity 

to modify the composition of organic emissions on a relatively short time scale. The “ambient profile” 

depends on the local emissions, transport, and physical chemical characteristics (temperature, particle 

surface area and oxidant concentrations). A better idea would be to look at distributional characteristics 

characterized by meteorological regimes developed from multiple years of data.

The objective “Initial and Boundary Conditions” to grid models give no indication as to what scale?

PAMS provides point measurements and grid models are typically 12 km x 12 km (can be as small as 4 

km x 4 km) so what are they looking for? An important unasked question is how spatially representative 

are the measurements at any given PAMS site. Also if the measurements are to provide initial and 

boundary conditions, they cannot also serve to evaluate the model. These objectives need to be separated 

and two independent sets of data need to be developed: One that represents inputs to the mode and 

another that can be used for evaluation purposes.

“Provide a representative, speciated ambient air database which is characteristic of source emission 

impacts.” Source apportionment has and can be done on such data, but the problems related to varying 

species reactivity. Our experience is to work with nighttime values when their stability is much greater. Also 

plumes represent significant problems. In many locations, the background of reacted materials and modified 

profiles makes source identification very difficult.

The development of “trends” also has to take short-term reactive variability into account.
D-52

The installation of additional monitors should really be at the discretion of the state or local agency 

based on their analysis as to whether additional data would provide better planning to be achieved.

For a research objective, it is always desirable to have population exposure measurements. Some of the 

PAMS species are also HAPS so to some extent their hazard could be assessed. However, the question is 

whether there are additional resources available beyond the monitoring necessary to protect public 

health with an adequate margin of safety. 

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

It is not clear that the specification of the multiple sites is connected to the modeling that it supposed to 

support. 

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

Potentially. If we are concerned with transported ozone from Asia having an impact on the US, then 

transport is clearly much more important than we thought when setting up the PAMS network 15 to 20 

years ago. There needs to be modeling to estimate transport with reaction to determine the relative 

impacts of local and distant sources. If VOC sources and transport are important sources of VOC in the 

non-attainment areas, then it may be important to have data for the transported component to identify a 

strategy to reduce the local ozone.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)?

Only if there is a priori indications (like model results) that having these data will actually contribute to 

improving the modeling and control strategy development. It has seem that the PAMS data have been 

underutilized in the past and thus, expanding the monitoring without a clear indication that the cost will 

provide adequate benefits in better models and control strategies, then there is no justification for the 

expansion.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

Mobile measurements might be helpful in finding local sources and assessing the emissions factors, but 

those are specific studies that should be left to the authorities who are developing the SIP. It is hard to 

see a lot of value of short-term measurements except for source characterizations. 

The presentation on the IAGOS was intriguing in its possibilities to help to look at spatial variability of 

ozone and likely locations for ground level non-urban PAMS sites.
D-53

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

There are advantages of winter measurements when oxidant levels are lowest and reactions are slowest 

because of decreased temperature. If assessment of dispersion or source identification/apportionment is 

the goal, winter sampling can be useful. Otherwise, it is hard to see it is likely to be very helpful.

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list?

It may be useful to assess the role of VOCs in producing SOA as well as ozone. Thus, species that 

represent significant SOA precursors could assist in PM strategy development and provide additional 

value to the PAMS measurements.

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

I do not know. I know when we analyzed data, there were a number of species that were BDL for most 

samples. Thus, it is a good idea to do a useful data inventory to see what the typical number of times that 

data are greater than the MDL and above the limit of determination. If all the data are just below or just 

above the MDL, then there is no information content and it is not worth including them. However, this 

would be on a site-by-site basis.

We have also mined data from Houston and found several of the peaks in the chromatograms were well 

related to ozone. However, we have no idea what they are. There needs to be some flexibility to 

carefully look at the data and decide what species are likely to be useful in control strategy development. 

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

It really depends on the objectives. The increased time resolution of the auto-GC is advantageous for the 

source apportionment. However, for just providing input into the models, the increased time resolution 

may not worth the worth the cost and effort so canisters probably makes more sense. 

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites?

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

With modern GCs and computers, it is hard to imagine that better systems could not be implemented, 

but it is not something I have done or looked at.
D-54

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

It is not clear to me that non-specific measures of organic vapor species concentrations are very useful.

There is such a wide range of reactivity that a TNMH measurement is not likely to be strongly related to 

ozone formation potential. If monitors were available that mimicked the lumping of compound types 

that occurs in the chemical transport models, then they might have value.

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

No. It should be possible to use models and some screening measurements to ascertain the impact of 

carbonyls and their photolysis on ozone formation. If the a priori data suggests a limited role in a given 

geographical area, why spend money on additional analyses?

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

I do not have any useful insights into this problem.

Charge Question 16: What other methods should be considered as an alternative to the manual TO-14A 

method for carbonyl sampling?

I do not have any useful insights into this problem.

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment 

in the PAMS network? What additional evaluations are necessary to determine the suitability for use in 

the PAMS network?

There were several in developments, but I have not followed their testing.

Should EPA pursue the development of a single analyzer capable of measuring NO, NO2 and NOy?

Obviously if everything can be rolled into a single instrument, it reduces the cost of operation and 

calibration and potentially capital costs. First step is to have definitive systems for measurement of NO2 

and NOy to start with.

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites?

I do not see this to be very useful if it is ONLY a PAMS site. If it is a more comprehensive monitoring 

site, it is generally useful to have additional vertical profiling if it can be afforded.
D-55

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

Not clear. We can certainly do trajectory ensemble analyses (PSCF, RFA, SQTBA, etc) to look at likely 

source areas of transported VOCs although again variable reaction rates makes such analyses more 

problematic.

Charge Question 21: How can PAMS data best be used? What specific data analyses should be conducted? 

There are various multivariate calibration methods that can be applied to explore the relationships between 

specific VOCs and current or future ozone. These methods could be used to look at the sensitivity of ozone 

to the VOC concentrations.

The objectives need to be sharpened and then specific data analysis tasks can be developed to address those 

objectives. Right now, there is a disconnect between the data uses and the panoply of objectives.

Charge Question 22: How should any recommended data analyses be implemented? Should these analyses 

be conducted at the state, regional, or national level? 

It needs to be done on the scale necessary to answer the specific questions related to the elevated ozone in a 

particular area.

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis?

It is hard to see where the money has gone. There does not seem to be a lot of obvious uses of the data 

as reflected in the scientific literature. We have explored the data for source apportionment and there can 

be some results obtained, but it has not proven very insightful in terms of helping to improve control 

plans. In particular, we have not seen a lot of efforts to relate the PAMS data to the ozone values. We 

have done some work in this area that actually provided some reasonable predictive capability for ozone 

forecasting,3,4

 3

Application of Artificial Neural Networks to Modeling and Prediction of Ambient Ozone 

Concentrations, L. Hadjiiski and P.K. Hopke, J. Air Waste Manag. Assoc. 50:894-901 (2000). 4 Data Mining of the Relationship Between Volatile Organic Components and Transient High-Ozone 

Formation, F. Gan and P.K. Hopke, Anal. Chim. Acta 490 153–158 (2003).

but given the amount of funding that is being devoted to data analysis, there does not 

appear to be much return. 
D-56

Comments from Dr. Rudolf Husar

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated? 

If the ozone NAAQS is tightened, the permissible ozone levels would become comparable to the ozone 

levels due to ‘extra-jurisdictional’ source, i.e. not controllable by correct management procedures. 

Identifying the corresponding Policy-Relevant Background (PRB) of O3/Precursors is becoming an 

increasing challenge. Hence, characterization of PRB should be given a high priority of the re-designed 

PAMS program. 

Charge Question2: What additional objectives should EPA consider for the PAMS program at this time? 

Better characterization of Policy Relevant Background. PRB ozone/precursors are those that are not due 

to anthropogenic emissions within the US, Canada or Mexico. The primary PRB contributions are forest 

fires, biogenic emissions and anthropogenic emissions from outside North America.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage? 

Yes, measurements near sources that contributes to Policy Relevant Background.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)? 

PAMS measurements at locations that elucidate Policy-Relevant Background (PRB) ozone and 

precursors would be desirable. These include regions of smoke emissions, NW US and SW US. Both 

regions have non-industrial, seasonal VOC emissions that significantly impact on downstream receptor 

areas. 

Also, regions impacted by long-rage transported O3 and precursors would also need to be characterized. 

The regions include the Mexico and Canada border regions. The trans-pacific transport of O3/precursors 

fro East Asia would also require characterization.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program? 

Very specialized mobile sampling may be useful for source characterization of ozone precursors for 

special cases such as major fires. However, mobile sampling should not be used for routine monitoring.
D-57

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included? 

More flexible approach is desired. The minimum requirement is that major geographic and seasonal 

ozone regimes be identified; each ozone regime to be defined by seasonal/regional extent; source 

pattern; chemical integrations and transport pattern. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors? 

The April-September ozone season would need to be evaluated based on detailed analysis of the 

available PAMS and FRP ozone monitoring data. Such analysis would probably identify the regions 

where monitoring should be extended or shortened.

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list? 

The target VOC list should include the best-available tracers/indicators for fires, biogenic emissions and 

as well as for anthropogenic emissions. 

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations? 

Satellite remote sensing of some O3 precursors appear to be the most promising observations to improve 

the understanding of ozone precursor emissions, ozone formation, and transport. The daily coverage of 

satellites along with ~10km spatial resolution constitutes a consistent global-scale dataset for several 

atmospheric chemical constituents.

In particular, the OMI spectral reflectance sensor on Aura satellite platform offers column-concentration 

measurement of NO2 and formaldehyde (a biogenic emission tracer) and ozone. The OMI data, 

available since 2004, constitute a unique contribution, particularly to the estimation of organic emissions 

from biogenic and fire emissions.

The MOPITT and MODIS sensors on Aqua/Terra satellite platforms produce column-concentrations 

data for CO and aerosol respectively. These observations available since 2001 have improved our 

understanding of non-industrial sources and emissions, primarily from episodic fire sources. 

Satellite sensors have numerous limitations in accuracy, precision and spatio-temporal coverage. The 

column-concentrations measurements are difficult to calibrate and have interferences from clouds, other 

chemicals and surface reflectance. Hence, satellite observations are best used in conjunction with other 

observations and/or chemical transport models. 
D-58

Surface-based column observations e.g. for ozone (Dobson instruments) and aerosol optical thickness 

(Sun-photometers) provide suitable, high-grade ground-truth for the satellite sensors. These should be 

utilized in conjunction with the satellite data.

At this time I am not ware of a systematic effort to fuse the surface-based measurements with satellite 

columnar observations. Evidently, the methodologies for such multi-sensory data fusion need to be 

developed before one can take advantage of the new observation platforms. 

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites? 

I doubt that adding profilers or radiosondes at PAMS sites would improve the understanding of transport 

significantly. My reasoning is that I don’t see how these observations are incorporated or assimilated 

into the current analysis or modeling efforts. Hence, rather than adding new sites, I would focus on 

developing techniques for the assimilation of observations into the MM5/CMAQ models.

Charge Question 20: How should NOAA data be incorporated into the PAMS program? 

The variety of NOAA atmospheric observations and models could be incorporated into different types of 

analyses. Surface meteorological observations are helpful for local transport and removal analyses. 

Upper air observations (Raisosonde and Profilers) along with the NOAA regional met that assimilates 

these observations could be used in the regional CMAQ model.

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted? 

There should be more emphasis on diagnostic modeling as an approach to data analysis. 

Currently, emission control actions rely heavily on the CMAQ model but the model performance for 

ozone simulations is rather marginal. In fact, it is said that the CMAQ O3 simulation performance has 

not improved over the past decade. Hence, it may be time for newer ideas such a combined 

analysis/modeling approach rather than the usual separate modeling and observation-based analysis. 

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level? 

Clearly, the PAMS analysis approaches of the past were inadequate. Maybe a participatory process 

would be more productive and beneficial. It would be helpful to (1) identify the key PAMS stakeholders 

(e.g. EPA/Regions, states, observations community, modeling community, data analysts/researchers..(2) 

seek to understand and their needs and possible contributions (3) collectively formulate the analysis 

plans of which outcome would benefit all stakeholder participants. 

EPA could be the catalyst in organizing and facilitation such a participatory process. EPA could use 

multiple vehicles including the STAR research grant program. The approach would include a prudent 

combination of regional (e.g. local source characterization) and national-scale analyses (e.g. modeling, 

transport). 
D-59

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis?

More funding should be allocated for analysis. However, the related question is how could EPA catalyze 

more PAMS analysis? The recognition that PAMS data are under-analyzed and under-utilized has been 

on OAQPS radar for at least 15-20 years but remedies were scares. Is the NESCAUM PAMS analysis 

effort a possible approach? How did it happen? Could it be replicated by other states/regions?
D-60

Comments from Dr. Peter H. McMurry

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program? 

My thinking is that mobile measurements might best be used in research studies aimed at understanding 

factors (emissions and spatial patterns of emissions from anthropogenic and natural sources, 

meteorology, etc.) that affect local ozone concentrations. For example, aircraft measurements carried out 

during the Texas 2000 Air Quality Study, together with models, provided information that was used to 

assess causes of high ozone levels that have been observed in the Houston area (Kleinman et al. 2002; 

Tanaka et al. 2003; Jiang and Fast 2004; Lei et al. 2004; Berkowitz et al. 2005; Murphy and Allen 2005; 

Fast et al. 2006). Similar studies have been done elsewhere, such as in the San Joaquin valley (where the 

interplay between ozone and agricultural emissions was a focus), Los Angeles, New York, etc. In his 

comments, Dr. Yousheng Zheng gave good examples of ways in which mobile PAMS measurements 

were effectively used for diagnostic purposes in the Baton Rouge area.

Temporary sites may also be useful for modifying PAMS network design to meet needs associated with 

changes in emissions patterns. Changes can occur as a result of successful implementation of emissions 

controls programs, population growth, or new industrial sources. 

Thought should be given to the most effective approach for using temporary or mobile sites. Much has 

been learned from short-term, intensive research programs that include state-of-the art measurements 

and modeling. Such studied can be designed, for example, to use specialized aircraft platforms that have 

been developed at considerable expense and with the benefit of decades of experience. One possibility 

might be to make more use of intensive campaigns coordinated by state and local agencies rather than 

mobile PAMS sites operated by state and local agencies.

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

I do not have direct experience with the collection or use of TNMH data.

However, comments by other Subcommittee members make a convincing case that TNMH monitors can 

provide valuable supplemental information for PAMS networks. For example, Yousheng Zheng pointed 

out that since TNMH measurements can be completed in about one minute, TNMH data can be used to 

trigger more expensive PAMS sampling when high concentrations are detected. Furthermore, TNMH 

and NOx can be measured at similarly high time resolution. This information on ozone precursor gases 

provides essential information for models. 

Charge Question 20: How should NOAA data be incorporated into the PAMS program? 

I have looked at the NOAA web site (http://madis-data.noaa.gov/cap/profiler.jsp), and it seems clear that 

this information would be of some value to chemical-transport modelers, who need to understand 

relationships between chemical transformations, emissions, and the ozone formation.
D-61

I do not have sufficient experience with air quality modeling to know how these data would be 

incorporated into models. Other Subcommittee members will be better equipped to elaborate on 

potential uses of these data.

References Cited:

Berkowitz, C. M., C. W. Spicer and P. V. Doskey (2005). "Hydrocarbon observations and ozone 

production rates in Western Houston during the Texas 2000 Air Quality Study." Atmospheric 

Environment 39(19): 3383-3396.

Fast, J. D., W. I. Gustafson, R. C. Easter, R. A. Zaveri, J. C. Barnard, E. G. Chapman, G. A. Grell and S. 

E. Peckham (2006). "Evolution of ozone, particulates, and aerosol direct radiative forcing in the 

vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model." Journal of 

Geophysical Research-Atmospheres 111(D21).

Jiang, G. F. and J. D. Fast (2004). "Modeling the effects of VOC and NOX emission sources on ozone 

formation in Houston during the TexAQS 2000 field campaign." Atmospheric Environment

38(30): 5071-5085.

Kleinman, L. I., P. H. Daum, D. Imre, Y. N. Lee, L. J. Nunnermacker, S. R. Springston, J. WeinsteinLloyd and J. Rudolph (2002). "Ozone production rate and hydrocarbon reactivity in 5 urban 

areas: A cause of high ozone concentration in Houston - art. no. 1467." Geophysical Research 

Letters 29(10): 15.

Lei, W. F., R. Y. Zhang, X. X. Tie and P. Hess (2004). "Chemical characterization of ozone formation in 

the Houston-Galveston area: A chemical transport model study - art. no. D12301." Journal of 

Geophysical Research-Atmospheres 109(D12): 12301.

Murphy, C. F. and D. T. Allen (2005). "Hydrocarbon emissions from industrial release events in the 

Houston- Galveston area and their impact on ozone formation." Atmospheric Environment

39(21): 3785-3798.

Tanaka, P. L., D. D. Riemer, S. H. Chang, G. Yarwood, E. C. McDonald-Buller, E. C. Apel, J. J. 

Orlando, P. J. Silva, J. L. Jimenez, M. R. Canagaratna, J. D. Neece, C. B. Mullins and D. T. 

Allen (2003). "Direct evidence for chlorine-enhanced urban ozone formation in Houston, Texas." 

Atmospheric Environment 37(9-10): 1393-1400.
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Comments from Dr. Allen Robinson

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, if 

any, should be deemphasized or eliminated? 

Most important objectives are those directly related to photochemical assessment, and model and inventory 

evaluation.

“Provide a speciated ambient air database which is both representative and useful for ascertaining ambient 

profiles and distinguishing among various individual VOC. These data can later be used as evaluation tools 

for control strategies, cost-effectiveness, and for understanding the mechanisms of pollutant transport.”

“These data can later be used as a baseline for model evaluation and to minimize model adjustments and 

reliance on default settings.”

“Provide a representative, speciated ambient air database which is characteristic of source emission impacts. 

These data can be particularly useful in analyzing emissions inventory issues and corroborating progress 

toward attainment.”

Inventory and model evaluation seem especially important since these are core tools for developing control 

strategies.

Medium important objective

“Provide ambient data measurements which would allow later preparation of unadjusted and adjusted 

pollutant trends reports.” 

Pollutant trends are important. At this point we have 15 years of trends from PAMS sites. A subset of these 

sites could be used to extend the trends but continuing to run all of the historical sites to continue the trends 

seems like overkill. It would be a better to shift resources to new sites to more spatial resolution of the data.

Least important objectives:

“Provide local, current meteorological and ambient data to serve as initial and boundary condition 

information for photochemical grid models.”

There are many sources of meteorological data; not clear why that is a priority for PAMS. Not clear how 

important the data are for initial and boundary conditions for grid models. The data are very important for 

evaluating models.

The following two objectives seemed to be poorly defined / catchall. They seem to apply to any 

monitoring site and are not particular to PAMS. I would recommend deleting them.

“Provide additional measurements of selected criteria pollutants. Such measurements can later be used for 

attainment/nonattainment decisions and to construct NAAQS maintenance plans.”

“Provide additional measurements of selected criteria and non-criteria pollutants from properly-sited 

locations. Such measurements can later be used for evaluating population exposure to air toxics as well as

criteria pollutants.“
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Charge Question 2: What additional objectives should EPA consider for the PAMS program at this time? 

Redesigning PAMS to meet a broader set of objectives is consistent with the growing emphasis on multipollutant approaches. For example, PAMS could add explicit objectives around secondary organic aerosol 

precursors, air toxics, and indicators of global change. These are all worthy objectives.

A concern is that there are not sufficient resources to meet the current objectives never mind additional 

objectives. Therefore, broadening the goals of PAMS may reduce its effectiveness at photochemical 

assessment. Photochemical assessment seems like a critical goal since O3 and fine particle pollution are the 

most challenging criteria pollutants. Using PAMS to improve our understanding of inventories, models, 

control strategies, etc. for these secondary pollutants seems more important than air toxics.

A broader set of objectives likely could be achieved by more focused analysis of the existing PAMS data.

My sense is the lack of data analysis is a real weakness of the PAMS program. There needs to be specific 

data analysis tied to each PAMS objectives, including explicit analyses to determine whether the objective 

has been achieved.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites per 

PAMS area? What changes, if any, should be made in the number and spatial distribution of required sites? 

A disadvantage is that PAMS resources are concentrated in relatively small numbers of areas. Given the 

more regional nature of the O3 problem today, a more widely distributed network would make sense. For 

example, one could considering putting a PAMS sit in each O3 non-attainment area.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage? 

The coverage of the existing PAMS network is very geographically limited. Given the evolving and more 

regional nature of the O3 problem today (compared to early 90s) it makes sense to broaden the spatial 

distribution of PAMS.

There may also be specific areas that warrant more monitoring, such as areas of rapid development of oil and

gas industry in PA, WY, and TX or rapidly expanding urban areas. 

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites in 

addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all urban 

NCore sites)? 

Yes, but a simple rule of all non-attainment areas or all urban NCore sites probably does not make sense.

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program? 

Given the very limited spatial coverage of the current PAMS network, transportable sites that could be 

deployed in different locations might make a lot of sense, especially given current resource constraints. One 

would want to maintain a subset of fixed sites to continue to determine long term trends at a subset of 

locations.
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Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as possible to 

help states meet specific needs. In consideration of this potential objective, what are the committee's views 

on the relative merits of revising PAMS to be a very flexible program with relatively few requirements versus 

a program that is highly specified? If the more flexible model were adopted, what minimum requirements, if 

any, should be included? 

Consistent QA/QC procedures are important in order to facilitate regional or national analysis.

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) based 

on analyses of ambient data, meteorology, climatology, or other factors? 

The current PAMS monitoring season is too constrained: do June, July and August make the most sense in 

all locations? What about September? In the end it makes sense to define monitoring effort to match the 

specific characteristics of the area. This should be up to the state and local agencies operating the network 

and writing the SIPS. EPA should require them to justify whatever period they decide to monitor.

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list? 

Each compound should be justified in the context of photochemical assessment. For O3 we are worried about 

the combination of abundance and reactivity. EPA should consider the historical PAMS data through that 

lens and rank order the existing list of compound. EPA should consider adding compounds based on these 

criteria.

For SOA, the critical precursors are less clear. The traditional view is that single ring aromatics are the most 

important anthropogenic precursors and monoterpenes are the most important biogenic. Therefore those 

would make sense to measure. However, there is still significant uncertainty about the relative importance of 

different compounds as SOA precursors. 

Carbonyl and other small oxygenated compounds can provide substantial insight into atmospheric oxidation.

NATA provides risk rankings for various carbonyls and other air toxics.

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting from the 

target list? 

EPA should consider adding some additional biogenic VOCs, e.g. monoterpenes. They contribute significant 

to atmospheric reactivity in certain locations. Long-term trends of biogenic VOC would also provide insight 

into the effects of land use changes and climate change on emissions and atmospheric reactivity.

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus field 

deployed auto-GCs? 

Advantages for auto-GC are richer datasets (more time resolution theoretical without gaps). Auto-GC may 

have some sampling advantages relative to canister in terms of losses and reactions with canister walls.
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Advantage of canister is that it is a well-established technique that air monitoring agencies are comfortable 

with. Therefore, there is not significant uncertainty with respect to performance and cost.

Disadvantages with auto-GC seem largely uncertainty. How well will the next generation of instruments 

work? How much will it cost? What is cost of QA/QC of the larger volume of data?

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network? 

Additional evaluations:

Technical performance – intercomparison with establish methods across full range of atmospheric 

conditions.

Cost – technician time, maintenance, etc. required to run and analyze data in a PAMS context.

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program? 

I think that measurement TNMH is valuable since the suite of PAMS VOCs only constitutes a fraction (often 

a minority of total reactive organic gases). Therefore having a measure of the total allows one to quantify the 

total fraction of organics covered by the speciated measurements.

Alternatively one could consider a measure of total reactivity (e.g. techniques of Bill Brune and others).

These are research measurements today, but have a lot of bearing on the photochemistry assessment. One 

would carefully need to assess practicality for a PAMS application.

Charge Question 14: Should carbonyls be required at all VOC speciation sites? 

Carbonyls are an important part of ozone chemistry essentially everywhere. For example, aldehydes 

such as formaldehyde and acetaldehyde are ubiquitous and have relatively high MIR. Therefore, 

scientifically, there are compelling reasons to include them in PAMS. Furthermore, data on reactive 

intermediates can provide significant insight into oxidation mechanisms.

Some carbonyls are also air toxics, providing an additional motivation for measuring them.

A challenge is that carbonyls comprise a very broad class of atmospheric organics. In order to make an 

informed decision EPA should evaluate the relative importance of carbonyls to the general ozone reactivity 

based on existing data. This exercise could also help identify which carbonyls to target. Identifying target 

carbonyls based on abundance and reactive (i.e. importance to ozone problem) may help with method 

development.

If there are not adequate data to evaluate the relative importance of carbonyls to ozone problem then EPA 

should considering obtaining such data in order to make an informed decision before requiring them in 

PAMS.

However, no matter how scientifically attractive, there needs to be a robust a robust and inexpensive method 

for measuring them. My perception is that there are legitimate concerns with TO-11A and I am not aware of 
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another method. Given the importance of carbonyls it seems like priority should be better evaluation of 

current methods (e.g. TO-11a) or the development of new methods. 

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with the 

current TO-11A method for carbonyl sampling? 

No comment

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling? 

Robust measurement of a broad spectrum of carbonyls is a challenging problem. The suitability of canister, 

auto-GC, and potentially other in situ measurements should be (re-)evaluated. Certainly there are more 

robust in situ measurements for individual carbonyls such as formaldehyde in the research community. The 

research methods typically target individual carbonyls. Given the importance of carbonyls it seems like 

method development and evaluation should be a priority. Robust measurements of one or two carbonyls may 

be of more use than poor quality data for a lager number.

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment in the 

PAMS network? What additional evaluations are necessary to determine the suitability for use in the PAMS 

network? 

No comment.

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected surface 

measurements and in what locations would complement vertical profile and total column observations? 

No comment.

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS sites? 

Charge Question 20: How should NOAA data be incorporated into the PAMS program? 

No comments.

Charge Question 21: How can PAMS data best be used? What specific data analyses should be conducted? 

There are many interesting and important ways to use the PAMS data –

Evaluation of chemical transport models and inventories

Trends in secondary organic aerosol precursors
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Trends in biogenic compounds as indicators of land use change and climate change

Evaluation of NATA and estimate of air toxics exposures (e.g. Logue et al. AE 2010)

It is not clear that the data are being used extensively in this fashion

Charge Question 22: How should any recommended data analyses be implemented? Should these analyses 

be conducted at the state, regional, or national level? 

I would look at some at the procedures that IMPROVE and other monitoring networks have implement to 

encourage data analysis. Regional or national analysis of monitoring network such as IMPROVE, 

AEROCOM that seem to be much more successful with having ) for ways in which to increase 

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis? 

I was surprised to see that 25% of PAMS funding is allocated for data analysis. I see very few studies 

utilizing PAMS in the peer review literature. Given the nature of the data I find this surprising.

Therefore this raises the question in my mind of whether really 25% is being spent and if so what is it 

being spent on. My sense is there could be much more value from the PAMS data given appropriate 

analysis.

The IMPROVE data are widely used. There are likely some lessons learned from IMPROVE about how 

data analysis. IMPROVE data are available through a well-organized website which allows researchers 

easy access. The IMPROVE “staff” also actively work on the data to answer scientific questions and 

improve methods.
D-68

Comments from Dr. Armistead (Ted) Russell

Attached are some plots from a project conducted about 7 years ago that used PAMS data. I think you 

might find the comparison of interest. It is important to note, however, that this type of analysis takes a 

bit more time to get the data and work with it.

Figure 0.1 Time Series Plot of Simulated and Observed Surface NOZ Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta

Figure 0.2 Time Series Plot of Simulated and Observed Surface Total Nonmethan Organic Compounds Concentrations at PAMS 

Station with AIRS code of 130890002 in Atlanta
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Figure 0.3 Time Series Plot of Simulated and Observed Surface PAMS Hydrocarbons Concentrations at PAMS Station with AIRS 

code of 130890002 in Atlanta

Figure 0.4 Time Series Plot of Simulated and Observed Surface ALK1 Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta

Figure 0.5 Time Series Plot of Simulated and Observed Surface ARO1 Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta
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Figure 0.6 Time Series Plot of Simulated and Observed Surface OLE1 Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta

Figure 0.7 Time Series Plot of Simulated and Observed Surface ISOPRENE Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta

Figure 0.8 Time Series Plot of Simulated and Observed Surface ETHENE Concentrations at PAMS Station with AIRS code of 

130890002 in Atlanta
D-71

Comments from Dr. Jamie Schauer

Charge Question 1: How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated?

The original PAMS objectives need to be evaluated by EPA to determine the incremental benefits of 

additional PAMS monitoring in the context of exiting time series of data. Objectives 1 and 3 use the 

word “useful” and it is not clear that the incremental measurements at most PAMS sites are indeed very 

useful. Likewise, Objective 2 and 4 address baseline data and trends, which after 15 years should be 

largely met if a large change in speciation is not observed at a specific the site.

Charge Question 2: What additional objectives should EPA consider for the PAMS program at this 

time?

The PAMS Program objectives should be updated to address critical monitoring needs to address 

uncertainties in ozone modeling and uncertainties in the sources of key species that impact ozone 

chemistry. In addition, the PAMS program should extend to address data needs for air toxics, SOA 

precursors, and gases important to climate change.

Charge Question 3: What are the advantages and disadvantages of the current design with multiple sites 

per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

To the degree that the multiple sites can continue to reduce the uncertainty in ozone modeling or add 

information that can advance the understanding of VOC sources, the multiple site approach should 

continue.

Charge Question 4: Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

Given the need to better improve the modeling of ozone at background sites to provide boundary 

conditions for ozone modeling, select PAMS sites should be considered to better understand VOCs in 

areas other than serious or above designation.

Charge Question 5: Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)?

Additional PAMS measurements at a subset of ozone sites needs to be driven by the ability to advance 

the understanding of VOC sources or improvement of ozone models.
D-72

Charge Question 6: What role, if any, should mobile or temporary sites play in the PAMS program?

There is a great need for both mobile and temporary sites but it does not seem wise to address this need 

within a monitoring network program. The infrastructure and knowledge base for using mobile and 

temporary sites would be different than that of existing PAMS data analysis in most instances. 

Charge Question 7: EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included?

Flexibility is good but the PAMS data needs to meet the needs of other stakeholders than just the states 

even if the states are the primary users of the PAMS data. To this end, adequate guidelines are needed to 

assure integration of PAMS data across different states and that the data can be used to meet the data 

analysis needs of diverse stakeholders.

I think regional and some national coordination is critical. As you indicate, giving each state a flexible 

program is probably not workable. The data needs to meet the needs of a variety of stakeholders and 

support national trends to the degree that the revised PAMS objectives warrant. I like the RPO 

coordination as I do not see the state led flexible programs as workable given the point that you outline 

and the fact that many states would not be able to effectively manage and support such a flexible 

program from a planning and technical perspective. I think the RPO model could do a good job with the 

ozone goals and the potentially added air toxics goals if indeed this was added. However, any added 

objective associated with climate relevant gases probably need to have a more nationally coordinated 

effort that focuses on trends. 

Charge Question 8: Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors?

In the context of broader objectives addressing air toxics, SOA precursors, and gases important to 

climate change, the period of monitoring should be expanded. 

Charge Question 9: What criteria should EPA consider when re-evaluating the PAMS target VOC list?

Re-evaluation of the PAMS target list should be conducted in the context of ozone modeling 

uncertainty, source apportionment of VOCs, and monitoring needs to air toxics, SOA precursors, and 

gases important to climate change

Charge Question 10: Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

Not sure. Need to consider the revised or prioritized objectives to make this assessment.
D-73

Charge Question 11: What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

Auto-GCs may present a problem for some states in terms of manpower of field staff and expertise of 

field staff. However, auto-GCs have the potential for advancing source attribution efforts.

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

This needs to be assessed in the context of the skill sets of air monitoring field staff at diverse states.

Charge Question 13: What role, if any, should TNMH monitors play in the PAMS program?

The TNMH measurement is a good reference metric and should be maintained. Since all VOCs are not 

measured, the TNMH provides an important reference for measurements.

Charge Question 14: Should carbonyls be required at all VOC speciation sites?

The requirement of carbonyls needs to be driven by modeling needs and air toxic data needs.

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

No comments

Charge Question 16: What other methods should be considered as an alternative to the manual TO-11A 

method for carbonyl sampling?

No comments

Charge Question 17: Are direct measurement NO2 or photolytic NO2 analyzers suitable for deployment 

in the PAMS network? What additional evaluations are necessary to determine the suitability for use in 

the PAMS network?

No comments
D-74

Charge Question 18: What observational approaches (surface based sondes and optical remote sensing, 

aircraft platforms, satellites) are best suited to assist such assessments? What routinely collected 

surface measurements and in what locations would complement vertical profile and total column 

observations?

No comments

Charge Question 19: Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites?

No comments

Charge Question 20: How should NOAA data be incorporated into the PAMS program?

Integration across agencies is important and will become more important as climate change needs to be 

addressed. Incorporating NOAA data will help these efforts in the short and long run. 

Charge Question 21: How can PAMS data best be used? What specific data analyses should be 

conducted?

I am not sure that this is a good question. PAMS monitoring needs to be driven by regulatory and 

scientific questions and should not happen in reverse. If data analysis needs cannot be identified then it 

seems hard to justify the PAMS network, Likewise, if the existing PAMS network cannot meet the data 

analysis needs than changes in PAMS is needed.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

There should be common goals that develop year to year that should be directed nationally or regionally 

but adequate flexibility is needed within the states to assure that local needs are being met.

Charge Question 23: Should more or less of the PAMS funding be allocated to data analysis?

Seems about right but given the use of PAMS data that I have seen, it seems hard to believe the 25% of 

the funds are being used for useful data analysis. It may be that these analysis results are not being made 

available to the broader community but like a bigger visibility and impact of PAMS data is needed.
D-75

Comments from Dr. Jay Turner

Charge Question 12: Are the new commercially available auto-GCs appropriate for use at PAMS sites?

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network?

There have been promising developments in the auto-GC technology over the past fifteen years. One 

example is the Syntec Spectras Ozone Precursor Analyzer5

 5 No endorsement should be inferred from any mention of specific manufacturers or consulting firms.

(Synspec BV) which is an example of a dual 

GC/detector system with one analyzer for C2-C5 compounds and another analyzer for C6-C10 

compounds. While I am not personally familiar with these analyzers, they share a measurement platform 

with the Syntec Spectras Benzene/BTEX analyzer that has a favorable reputation. Several other makes 

and models of field auto-GC units are available. As noted in the white paper, in addition to the 

conventional dual GC/detector system there might be merit in simplifying the target analyte list to 

permit use of a single GC/detector. At least one state briefly brought on board a third party to operate a 

GC/MS system for one seasons of PAMS measurements. Given the advantages of continuous hourly 

data over periodic, more time-integrated data – especially for applications such as chemical transport 

model validation and source apportionment – there is merit in documenting their current capabilities.

There are many factors to be considered including but not limited to data quality, field robustness, 

required level of expertise to operate and maintain the analyzers, and cost.

I strongly believe a technical and operations evaluation is warranted, and I suggest a two-phase 

approach. First, users of auto-GCs for PAMS and related applications should be surveyed. This user 

group includes state/local agencies and also several other organizations engaged in long-term monitoring 

projects. While this survey might capture relatively little experience with the newer instruments, it 

would serve to document what has – and has not – worked well in the past. Second, a field evaluation 

should be conducted, ideally at one of the PAMS sites and ideally for at least a month. The challenges to 

this evaluation should not be underestimated; while it would be ideal to have a third party operate the 

instruments, this might be impractical depending on the scope of the study. It is appreciated that such an 

evaluation does not adequately capture certain important components of a field evaluation, such as longterm performance and maintenance requirements, but could be very useful towards elucidating 

instrument performance under ideal conditions. 

Charge Question 15: What issues have been addressed, and what issues still need to be addressed with 

the current TO-11A method for carbonyl sampling?

First, the carbonyls target analyte list must be evaluated – is the goal to keep the focus on formaldehyde, 

acetaldehyde, and acetone, or to expand the list of analytes? My understanding is that several additional 

carbonyls are often detected and reported by the analytical laboratories but only these three are typically 

reported to AQS. 

The TO-11A method collects carbonyls using DNPH cartridges. Potential issues include positive and 

negative artifacts from contamination, reaction with ambient oxidants (especially ozone), collection 

efficiency and carbonyl generation on the substrate. It was my impression that most of these issues can 

now be controlled. For example, an ozone scrubber is now typically integrated with the DNPH cartridge 
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and is swapped out with each sample. This approach places the quality control burden on the analytical 

laboratory preparing the sampling cartridges rather than on the field operators. Improved handling 

protocols have presumably lowered blanks concentration values and reduced the frequency of 

contamination.

The most-recent NATTS QA Annual Summary (calendar year 2008) demonstrates network-wide overall 

precision of ~20% for formaldehyde which is similar to many of the canister-based VOC precisions.

However, five of the 15 stations with precision data exceeded the 15% MQO and one station was nearly 

50%. Many states perform the analysis in house, and proficiency testing of a single sample across 

fourteen laboratories exhibited a mean bias within the 25% MQO. Of course, these QA assessments do 

not inform us about the impact from many of the aforementioned sources of artifacts.

While initially it was my impression that most the DNPH-based carbonly sampling and analysis issues 

can now be controlled, a cursory review of the literature suggests otherwise and a more-detailed review 

is needed. 6,7

 6 See D.D. Parrish and F.C. Fehsenfeld (2000) Atmos. Environ., 34, 1921-1957 and references therein for work prior to 2000. 7

 C. Hak et al. (2005) Atmos. Chem. Phys. Discuss., 5, 2897–2945.

To my knowledge there has not been a recent formal evaluation of the DNPH-based 

method(s) and it is warranted. Also, previous work has focused on formaldehyde and we need better 

documentation of performance for the other target carbonyls. Several research groups and analytical 

laboratories have extensive experience with carbonyl sampling and their perspectives would be valuable.

Charge Question 22: How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

This is a very important question that is tied back to the monitoring objectives. Since the objectives 

might be revised through the PAMS re-engineering process, it might be necessary to cycle back to this 

question after such changes have been defined.

Analyses would likely be implemented at all of the above levels. It would be very helpful to have EPA 

(perhaps through a subcontractor) prepare annual summaries including an independent evaluation of the 

data quality and some basic trends analyses (e.g. descriptive statistics, spatiotemporal patterns, etc.).

Previous PAMS data analyses (including but not limited to the series of work products by Sonoma 

Technology, Inc., for various clients) and network assessments can be used as a starting point to define 

the candidate analyses. Part of this effort could include repackaging the data in a few of the more 

common formats likely to be used by stakeholders such as regional planning organizations and 

state/local agencies. 

To promote more widespread use, the data must be available through a user-friendly portal. While a 

VEIWS- or DataFed-like platform is ideal, there other options such as the AQS data polls periodically 

performed by EPA and made available (in AQS format) through a web site. The latter is a bit clunky and 

requires substantial reformatting by the user, but I have found these packaged data sets to be invaluable.
D-77

Comments from Dr. Yousheng Zeng

Charge Question 1 - How should EPA prioritize the current PAMS objectives? What current objectives, 

if any, should be deemphasized or eliminated?

Response: In general, some of the current objectives are vague and subject to different interpretation. 

Through this re-engineering effort, the objectives should be stated more clearly. My comment on each of 

the current PAMS objectives is provided below: 

• Provide a speciated ambient air database which is both representative and useful for 

ascertaining ambient profiles and distinguishing among various individual VOC. These data can 

later be used as evaluation tools for control strategies, cost-effectiveness, and for understanding 

the mechanisms of pollutant transport. 

- I think this objective is still valid. However, I have some concern on the word 

“representative”. The kind of speciated VOC monitored by current PAMS network indicate a 

strong spatial variability and typically there are only a small number of PAMS sites in a 

nonattainment airshed. It will be difficult to make the data “representative” unless EPA is 

willing to allocate significantly more fund for the PAMS program and add more stations. I 

think that the data is still “useful” and I would give this objective a high priority.

• Provide local, current meteorological and ambient data to serve as initial and boundary 

condition information for photochemical grid models. These data can later be used as a baseline 

for model evaluation and to minimize model adjustments and reliance on default settings. 

- The meteorological data (met data) are collected by various air monitoring networks (e.g., 

SLAMS) that typically provide more data points in a given airshed than the met data 

generated by PAMS sites. Although PAMS network can contribute more met data, met data 

is not unique to PAMS network, The phrase “ambient data” should be clarified. If it refers to 

a large number of speciated VOC and some speciated NOx, that would be specific to PAMS 

network, but I am not sure these data have been used as initial and boundary condition for 

photochemical grid models. The data points provided by PAMS’ limited number of sites in 

an urban airshed are isolated and scant, and they may represent very localized condition due 

to atmospheric lifetime of the speciated VOC and spatial variability. These scant data points 

may not be representative for a model that has 2-km or larger grid spacing. Depending on 

clarification of “ambient data”, I would either eliminate this objective or give it a low 

priority. 

• Provide a representative, speciated ambient air database which is characteristic of source 

emission impacts. These data can be particularly useful in analyzing emissions inventory issues 

and corroborating progress toward attainment. 

- I think this objective is valid and I would give it a high priority.

• Provide ambient data measurements which would allow later preparation of unadjusted and 

adjusted pollutant trends reports. 

- Again, it is not clear as to what “ambient data” this objective is referring, and what the 

adjustment is. If it is for trending, this objective could be covered by the first objective 

above. 
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• Provide additional measurements of selected criteria pollutants. Such measurements can later be 

used for attainment/nonattainment decisions and to construct NAAQS maintenance plans. 

- This should not be considered as an objective for PAMS. A PAMS site should have ozone 

and PM2.5 measured for a study of their relationship with their precursors measured at the 

site. These ozone and PM2.5 measurement may be used, along with other monitoring data, 

for attainment/nonattainment determination; but it is not an objective of PAMS. If EPA or a 

monitoring agency wants to have an additional measurement of a criteria pollutant (e.g., 

SO2), they can co-locate an SO2 monitor at the PAMS site; but it is not an objective of 

PAMS. I would eliminate this objective.

• Provide additional measurements of selected criteria and non-criteria pollutants from properlysited locations. Such measurements can later be used for evaluating population exposure to air 

toxics as well as criteria pollutants. 

- The “P” in PAMS is for photochemical assessment. Its main objective should be to provide 

information that can help achieve ozone (now maybe PM2.5 too) attainment, which is a 

widespread issue across the country. Some VOC ozone precursors monitored by PAMS are 

also air toxics. As a by-product or collateral benefit, these measurements yield additional 

information on air toxics. However, air toxics are typically a localized issue and can be 

addressed more effectively if it is not tied to the PAMS program. This objective should have 

a low priority.

Charge Question 2 - What additional objectives should EPA consider for the PAMS program at this 

time?

Responses: The main objective of the PAMS program is Photochemical Assessment, which helps bring 

an ozone (and maybe to some degree PM2.5) nonattainment area into attainment through better 

understanding of ozone precursors and their relationship with ozone formation. Everything else should 

be at most secondary. Some additional objectives may be stated if they are more specific or explicit, and 

address different facets or derivatives of the same basic relationship between ozone and its precursors 

(e.g., improving ozone forecasting).

The scope of PAMS program should not be broadened beyond the photochemical assessment and the 

relationship between ozone (maybe PM2.5) and their precursors. The ozone nonattainment is the most 

widespread problem in the nation’s air quality and has a far reaching economic impact. The PAMS 

program should focus on solving this problem and not be diluted by other objectives. If other pollutants 

(e.g. air toxics) are measured as a by-product of the PAMS program, that is fine. However, it should not 

be an objective of the program. When other objectives are considered, certain program elements, such as 

siting criteria, resources for measurement, etc., will likely be compromised to accommodate competing 

objectives. For example, air toxics may be a local issue. It may not be relevant or cost effective to make 

air toxics a PAMS program-wide objective. If EPA wants to gain some additional benefits and cost 

savings by leveraging an existing program, the consideration should be given holistically (including all 

air monitoring programs) in a manner similar to the approach discussed in the January 2010 draft report 

“Air Quality Observation Systems in the United States” prepared by Committee on Environmental and 

Natural Resources (CENR)/Air Quality Research Subcommittee (AQRS) rather than just considering the 

PAMS program.
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Charge Question 3 - What are the advantages and disadvantages of the current design with multiple 

sites per PAMS area? What changes, if any, should be made in the number and spatial distribution of 

required sites?

Response: The current four types of sites are useful as a guideline. They do not need to be a 

requirement. Some flexibility should be given to state and local agencies so that they can use this 

guideline and consider their specific situations and needs to set up PAMS sites. 

The function of Type 3 sites (maximum ozone concentration sites) may be covered by regular ozone 

monitoring station because by the time ozone level reaches its maximum concentration, many precursor 

species (particularly VOC precursor species) have been depleted to a minimal level that may not be 

detectable (Providence, 2010). With respect to Type 2 sites, see my responses to Charge Questions 6 and 

8.

Charge Question 4 - Should EPA consider requiring PAMS measurements in areas other than areas 

classified as serious and above for the ozone NAAQS to improve spatial coverage?

Response: When the PAMS program was initiated, the ozone standard was based on 1-hour averaging. 

Under the 1-hour ozone standard, there were more areas falling into the serious and above classifications 

(see Figure CQ4-1). Under the 1997 8-hr ozone standard, there are only seven areas classified as serious 

and above (two in Texas and five in California) see maps below (Figures CQ4-2). The PAMS network 

established under the 1-hour standard is still maintained due to the anti-backsliding policy. I don’t have 

classification information under the 2008 ozone standard (EPA should have this information and could 

provide the information to the panel for this discussion). The impression I have is that although there are 

more non-attainment areas under the 2008 standard, there may not be many more areas classified as 

serious and above. If that is the case, requiring PAMS monitoring only in the areas classified as serious 

and above will not improve spatial coverage compared to the current coverage. If there is a reason to 

improve spatial coverage, PAMS measurements may be required in areas below serious, e.g., moderate 

and above or some other criteria (a classification map under the 2008 standard, if available, will help 

formulate the criteria), or even some strategically selected rural areas. 
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Figure CQ4-1. Classifications of ozone nonattainment areas under previous 1-hour standard.

Figure CQ4-2. Classifications of ozone nonattainment areas under 1997 8-hour standard.
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Charge Question 5 - Should EPA consider requiring PAMS measurements at a new subset of ozone sites 

in addition to the traditional PAMS (e.g., maximum concentration sites in all non-attainment areas, all 

urban NCore sites)?

Response: No, at least not at the maximum concentration sites – see my response to Charge Question 3.

Charge Question 6 - What role, if any, should mobile or temporary sites play in the PAMS program?

Response: Mobile or temporary (or referred to as transportable) sites can play an important role in the 

PAMS program. Long-term/fixed sites can provide trends where as mobile or temporary sites are much 

more effective and cost efficient for diagnostic purposes, making them particularly suitable for Type 2 

sites. In 2005-2007, about two dozens of temporary ozone precursor monitoring stations were used 

around 16 suspected major precursor sources in the Baton Rouge ozone nonattainment area after the 

area was bumped up from serious to severe classification under the 1-hour standard. Some of these 

monitors were transportable (on a trailer platform) and they were moved seasonally based on prevailing 

wind direction. This temporary monitoring program provided very valuable data to either 

identify/confirm major precursor sources or exonerate other sources. The information helped the state 

agency in control strategy development and the ozone level in the area has been declining. 

Mobile or transportable monitors offer great flexibility. They can be deployed to a particular area of 

interest for a relatively short period of time. During this period, enough data can be collected to evaluate 

the levels and relationship of ozone, its precursors, and sources; whether the location is precursor 

dominating (earlier stage of the ozone formation process) or ozone dominating (later stage of ozone 

formation process); and how much more information could be obtained if the monitoring period is 

extended. After a period of time (e.g., one ozone season), the incremental gain in useful information 

tends to diminish (unless the main purpose is long-term trending). The stations can be re-deployed to 

another location. 

With transportable monitors, a PAMS network for an air basin can be designed more effectively and 

cost-efficient. It can consist of two fixed long-term sites (one for upwind urban scale monitoring, i.e., a 

Type 1 site, and the other for downwind urban scale monitoring, i.e., a Type 4 site) and two 

mobile/transportable monitors that will be deployed near major sources (i.e., function as Type 2 sites) 

or/and high ozone concentration areas (i.e., function as Type 3 sites). Compared to truly mobile (vehicle 

based) platform, transportable trailer based platform will be more cost effective because once deployed, 

these monitors will stay in a location for months. Truly mobile vehicle based monitors are more suitable 

to incident response applications. Two transportable units are desirable because they can be deployed as 

a pair, one for upwind and the other for downwind from suspected major precursor sources in Type 2 

applications. For Type 3 applications, one or both units can be deployed. The ozone monitoring results 

from the transportable monitors will not be used for NAAQS attainment/nonattainment designation 

purpose because they may not have long enough monitoring time at a location. 

Charge Question 7 - EPA has received feedback that the PAMS program needs to be as flexible as 

possible to help states meet specific needs. In consideration of this potential objective, what are the 

committee's views on the relative merits of revising PAMS to be a very flexible program with relatively 

few requirements versus a program that is highly specified? If the more flexible model were adopted, 

what minimum requirements, if any, should be included?
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Response: One of the advantages of a highly specified program is consistency, i.e., the data produced 

will be more comparable. Compared to other monitoring programs, the most important differentiator of 

the PAMS program is that it covers a much larger number of precursor species to help understand the 

ozone issues in specific areas. Comparability is more important for criteria pollutants (rather than 

precursors) and it has been achieved by other monitoring networks. I believe that getting useful data to 

help solve the ozone problem is the most important objective for PAMS and the comparability across 

multiple air basins or across the country is not as important. Therefore, I would favor a more flexible 

program. As far as siting is concerned, the 2 fixed sites plus 2 transportable sites model discussed in my 

response to Charge Question 6 could be used as minimum requirements. Significant flexibility can be 

obtained through the 2 transportable sites. Flexibility in other aspects of PAMS (e.g., target compounds, 

monitoring periods, etc.) is discussed in responses to later charge questions.

Charge Question 8 - Should the current PAMS monitoring season framework be retained or should the 

period for required measurements be revised (e.g., lengthened or determined on a case-by-case basis) 

based on analyses of ambient data, meteorology, climatology, or other factors? 

Response: The current minimum requirement of 3 months (Jun., Jul., & Aug.) are not representative for 

some areas. For example, in the Baton Rouge nonattainment area more ozone exceedances occurred in 

May than in July or August (see Figure CQ8-1).

Figure CQ8-1. Ozone exceedance days by month in the Baton Rouge nonattainment area (courtesy 

of Tim Bergeron, Louisiana Dept. of Environmental Quality)

Although June-August may have a higher temperature, more thunderstorms and rain are likely to occur 

during these months, which reduce ozone formation. In late spring and early fall, thunderstorms and rain 

are less frequent and the temperature is high enough to cause ozone formation. In 2010, 8 exceedances 

occurred in October, 4 in September, 4 in May, 1 in April, and only 1 or 0 occurred in each of the 

months from June through August. 

Ozone precursor data in non-ozone season can actually be very informative and useful. For many 

sources, emission rates are in the same order of magnitude throughout a year. In winter season, 

atmospheric physical and chemical process is less intense (less turbulent, less photochemical reactions, 

etc.). As a result, more precursors (particularly VOC precursors) are “preserved” better for monitors to 

pick up. This kind of data can be insightful in evaluating sources that could play a significant role in 

ozone formation when the temperature is higher and UV light is stronger in summer.

2%

9%

20%

16% 21%

14%

9%

10%

Exceedance Days by Month 

2001 to 2010

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct
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For these reasons, a case-by-case approach seems to be appropriate. I understand that EPA could retain 

the minimum requirement of 3 months (Jul-Aug) and let state and local agencies to expand the period if 

they need to. However, this minimum requirement will likely result in insufficient funding that will 

make it impractical for these monitoring agencies to expand the monitoring period even it is beneficial 

and justified. 

Charge Question 9 - What criteria should EPA consider when re-evaluating the PAMS target VOC list? 

Response: The following criteria should be considered in selecting PAMS target VOC list:

Reactivity in contribution to ozone formation: It is obvious that the VOC target list should include 

compounds that play an important role in ozone formation. The importance of individual organic 

compounds in ozone formation may be evaluated through atmospheric photochemical models such as 

CMAQ. A simple approach could be to use the Maximum Incremental Reactivity (MIR) (Carter, 2009). 

MIR is a way to measure incremental ozone impacts of VOCs under a set of scenarios representing 

conditions where ozone is most sensitive to VOC emissions. Different VOC species have different MIR 

values. For example, the MIR for propene is 11.57 g O3/g propene, and the MIR for propane is only 0.56 

g O3/g propane. MIR can also be expressed as mol O3/mol VOC species. Compounds with high MIR 

values should be given more weight than the ones with low MIR values in selecting target VOC for the 

PAMS program.

Expected concentrations: If the expected concentration of a VOC compound is below or near detection 

limit, there is limited value of including it in the target list. Based on the analysis of 14 years of PAMS 

data collected in San Joaquin Valley, there are multiple compounds barely detectable. Table CQ9-1 is a 

summary of PAMS VOC detectablity in San Joaquin Valley (Providence, 2010). 
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Table CQ9-1. Detectability of PAMS VOC in San Joaquin Valley from 1994-2007 (Providence, 

2010).

As shown in Table CQ9-1, eight compounds were detectable in less than 10% of samples. This is based 

on data from 1994 to 2007. Concentrations were higher in early years of this 14-year period. For more 

recent years, more compounds were below detection limits. Some compounds were barely above their 
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detection limits and the usefulness of the data is limited. Combining the detectability and MIR, a number 

of compounds could be eliminated from the target list.

Mobile or temporary monitoring platform discussed in Charge Question 6 can be an effective tool for 

screening detectability of compounds in a particular airshed. 

Charge Question 10 - Are there specific compounds that EPA should consider adding or subtracting 

from the target list?

Response: Instead of listing specific compounds, a systematic approach should be used in selection of 

target compounds. The criteria recommended in my response to Charge Question 9 above should be 

used in the decision of adding or subtracting compounds. Because MIR values for compounds are the 

same regardless of location, EPA should provide a longer list of potential target compounds based on 

MIR. Monitoring agencies should be given flexibility to use this longer list as a starting point and select 

compounds to be monitored with additional consideration of detectability in their specific airsheds. 

Currently compounds from biogenic sources are underrepresented. In the new target compound selection 

process, more compounds from biogenic sources should be considered.

Charge Question 11 - What are the advantages and disadvantages of manual canister sampling versus 

field deployed auto-GCs?

Response: Below is a side-by-side comparison of canister sampling vs. auto-GC (Zhou et al, 2007). 

Canister Sampling Auto-GC

• Simple

• Grab samples

• Low cost for small number of 

samples; the cost advantage 

diminishes as sampling frequency 

increases

• Delayed results

• Sophisticated

• Continuous operation

• High capital cost; it becomes more 

cost effective when sampling 

frequency increases

• Quick turnaround; near real-time if 

automated

Auto-GC has been used in Texas, Baton Rouge nonattainment area, and other areas. Having hourly 

VOC precursor data that matches hourly NOx data and hourly ozone data is very helpful in 

understanding the ozone formation process and developing ozone strategies. Preliminary auto-GC data 

can be made available within an hour. Compared to the canister method, the data from auto-GC is much 

more timely and relevant. Part of reason that a vast amount of data is generated by current canister based 

PAMS sites but not effectively used is that the canister data is spotty (1-3 data points per day, a couple 

of days per week) and not timely (1-2 weeks after the samples are collected). Because of the 1-2 weeks 

of time delay, the data is not actionable and is not relevant to most operational function of an agency 

other than a few data analysts. The canister method is somewhat a halfway approach. It costs money, but 

does not produce the desired results. If EPA is committed to the PAMS program, auto-GC method 

should be given a high priority in its PAMS re-engineering effort.

As discussed by Zhou (Zhou et al, 2007), auto-GC can be further divided into two modes of operation, 

hourly mode and triggered mode. The hourly mode will be very suitable to Type 1, 3, and 4 sites. 
D-86

However, it may miss or “flatten” the signal from precursor sources. It may not be representative of 

transit plumes. The triggered mode will minimize these shortcomings and better serve the purpose of 

Type 2 sites. 

Charge Question 12 - Are the new commercially available auto-GCs appropriate for use at PAMS sites? 

What additional evaluations are necessary to determine the suitability of auto-GC’s for use in the PAMS 

network? 

Response: GC configured for continuous or triggered ambient monitoring operations are commercially 

available from PerkinElmer and Agilent. Ecotech markets auto-GC that is specifically designed for 

continuous air monitoring. Currently majority of auto-GC deployed are PerkinElmer units. Agilent GC 

can be configured to achieve the same results. Both PerkinElmer and Agilent systems are built as more 

generic lab GC’s but used as continuous field monitoring instruments. Therefore there are many 

operational disadvantages associated with these instruments. The Ecotech AirmOzone is relatively new. 

I don’t know if EPA has evaluated the Ecotech system. It appears to be designed specifically for field 

application (as opposed to generic lab instrument) and therefore should be more durable for field 

deployment. However, I don’t know if the tradeoff is a lower performance. Through this review process, 

I became aware of another commercially available auto-GC made by Synspec. This instrument looks 

very promising.

It may be a good idea to invite vendors to participate in a comprehensive side-by-side performance 

evaluation (like EPA did for other monitors such as PM monitors). In addition to typical areas of such an 

evaluation (e.g., repeatability/precision, accuracy, linearity, detection limits, etc.), the following aspects 

specific to auto-GC for ozone VOC precursor monitoring should be addressed:

• Moisture management. Nafion dryers have been used to remove excess moisture in ambient air 

samples. Nation dryers may cause low recovery for some target compounds. In a triggered mode, 

the sample volume is smaller (because the VOC level is already elevated), and the moisture issue 

is less severe (Zhou, Zeng, Hazlett, & Matherne, 2007). 

• Field operability. Compared to other ambient air monitoring analyzers (e.g., ozone, NOx, etc.), 

operations of PerkinElmer and Agilent auto-GC are awkward because they are fundamentally a 

lab bench top instrument designed for manual operations. Data acquisition is very cumbersome 

and cannot be easily integrated into typical ambient air monitoring data acquisition system. The 

Synspec ozone precursor analyzer and Ecotech AirmOzone may not have this issue. They all 

need to be field evaluated.

• Capability for Additional Compounds. As a result of this PAMS re-engineering effort, the target 

VOC list may be different from the current 56 compounds. The new compounds should be 

included in the evaluation. Separation of compounds is an important issue in any GC based 

measurement system. 

Charge Question 13 - What role, if any, should TNMH monitors play in the PAMS program?

Response: PAMS VOC samples are collected either on a fixed schedule or when an elevated VOC is 

detected by a TNMH monitor (i.e., triggered sampling approach). In the cases of triggered sampling 

approach (mostly Type 2 sites for precursor source-oriented monitoring), the TNMH monitors play a 
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critical role to generate a signal that triggers sample collection either by canisters or by auto-GC running 

in the triggered mode (Zhou et al, 2007). 

In addition to acting as a trigger, TNMH (or Total Non-Methane Organic Compounds, TNMOC, or 

simply NMOC) gives a reasonable indication of total VOC present in the atmosphere. The TNMH 

monitors have a short analytical cycle (e.g., Model 55i manufactured by Thermo completes each 

analytical cycle in 70 sec.) and can be averaged over a hour to match the NOx hourly monitoring data so 

that the monitoring data for both precursors (VOC and NOx) can be in sync with hourly ozone 

monitoring data. This will help understand the relationship between ozone and its two precursor 

categories (VOC and NOx). The lack of specificity in the TNMH data regarding particular species 

sometimes is made up for by its abundant data points in a near real time basis. It is a very useful tool in 

routine, action-oriented data analyses. 

The VOC compounds monitored by the current PAMS program are a subset of TNMH. Based on the 

San Joaquin Valley PAMS data analysis (Providence, 2010), the percentage of TNMH explainable by 

the sum of the VOC compounds monitored in the PAMS program can vary from 20% to over 100%. 

This suggests that the sum of VOC compounds monitored by GC in the PAMS program is not a good 

surrogate for VOC. TNMH monitors are universal monitors for hydrocarbon and they capture most, if 

not all VOC precursors. The difference between TNMH and the sum of VOC compounds measured by 

GC gives a clue on how much VOC is uncounted for in the current PAMS measurements.

Considering above factors, TNMH monitors serve an important role and should be included in the 

PAMS program. The shortcomings of TNMH analyzers should be recognized. The detector of the 

TNMH analyzer is a Flame Ionization Detector (FID), and it has different response factors for different 

compounds. This issue could be resolved unless hundreds of VOC species in the atmosphere were 

separated and calibrated individually. No instruments could do this. TNMH is the best method available 

to obtain some useful information on aggregated level of VOC in the atmosphere.

Charge Question 14 - Should carbonyls be required at all VOC speciation sites?

Response: Aldehydes generally have high MIR values (e.g., formaldehyde with MIR of 9.24, 

acetaldehyde with MIR of 6.34, etc.) (Carter, 2009) and several of them are fairly common in ambient 

air. As mentioned in response to Charge Question 13, up to 80% of TNMH is not counted for by current 

PAMS speciation. Significant portion of these unaccounted compounds could be carbonyls. Considering 

their high potential for ozone formation and common presence at levels comparable to other VOC 

species, carbonyls should be included in the PAMS program unless there are no adequate monitoring 

methods available. If carbonyls are added back to the PAMS program, some flexibility could be 

provided to monitoring agency. For a particular location, if 1-2 years of monitoring data show no 

significant carbonyls (indexed to MIR, or product of concentration and MIR), the monitoring agency can 

eliminate carbonyls from their PAMS program. Because instruments for carbonyl monitoring are 

different from other VOC species analyzed by GC, elimination of carbonyls can significantly reduce 

cost.

Charge Questions 15 – 18: No responses.
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Charge Question 19 - Is it necessary to collect upper air wind speed and wind direction data at PAMS 

sites? 

Response: Upper air wind data can be used for air monitoring, air modeling analysis, and air quality 

forecasting. One set of upper air data can reasonably cover a fairly large area (e.g., an area covered by a 

PAMS network for an urban area). I don’t have specific comments on this charge question, but this 

seems to be an area where multiple air monitoring programs (even broader than air monitoring 

programs) can share resources. It appears that some other programs may have more critical needs for the 

upper air data than the PAMS program, and if so, it would make sense to leave the measurement of these 

parameters to another program and focus on parameters that are specific to PAMS. 

The answer to this question also depends on how EPA plans to use this data in the PAMS program and 

what will be the new objectives of the PAMS program. 

Charge Question 20 - How should NOAA data be incorporated into the PAMS program? 

Response: No response.

Charge Question 21 - How can PAMS data best be used? What specific data analyses should be 

conducted?

Response: The PAMS program generates a large amount of monitoring data (over 50 VOC species in 

every sample). If these data are simply stored and not analyzed to the degree the program is designed 

for, the return on the investment in the PAMS monitoring effort is very small. It should be recognized 

that the PAMS program is a regulatory program. If the data generated by PAMS is only used for 

research, the program could be designed differently and managed by research organizations as special 

research projects. The PAMS program should be either re-engineered so that the data collected from the 

program is systematically analyzed and useful information is extracted regularly to support ozone 

attainment effort in each nonattainment area, or eliminated as a regulatory program all together.

In 1997 an EPA contractor prepared a PAMS Data Analysis Workshop Workbook for EPA 

(http://www.epa.gov/oar/oaqps/pams/analysis/). The Workbook addressed data validation, various 

specific data analysis techniques, and how the data could be used (primarily to support ozone attainment 

effort). However, the Workbook might not be instructive enough for some less experienced data analysts 

to follow and it has not been updated. As the EPA White Paper for this review stated, NESCAUM has 

performed a review of concentrations seen in the Northeast. Recently San Joaquin Valley Air Pollution 

Control District (SJVAPCD) commissioned a comprehensive analysis of PAMS data collected in 14 

years from 1994 to 2007 (Providence, 2010). The report of this analysis (without appendices) is 

available online http://www.providenceeng.com/P/Files/othertechnicalinfo/455-002-

001ER%20Final%20Report%20Narrative.pdf. There may be other systematic PAMS data analyses I am 

not aware of. It appears that these data analyses are not regularly done.

To help monitoring agencies in PAMS data analysis, EPA should consider using the 1997 Workbook as 

a starting point, updating the materials with more step-by-step instructions, incorporating other data 

analysis techniques (such as some used in the SJVAPCD PAMS data analysis), and providing 

monitoring agencies with a useful “toolbox” (a guidance document) for them to conduct PAMS data 

analysis.
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The new guidance document should include two types of analyses:

Daily Data Analysis: Attachment 1 is an example of tools for this type of PAMS data analysis. This type 

of tools can be automated and accessible online to agency staff through intranet (or to the public with a 

note specifying “preliminary data, subject to change after further data validation” or “validated data”). 

This type of routine data can be analyzed along with daily ozone forecast. An agency data analyst can 

perform a very quick analysis on a daily basis. After a period of time with this repeated analysis, the 

analyst will have a very good idea as to what is going on in the airshed and provide insight to the agency 

decision makers. A similar daily data analysis was performed by Louisiana DEQ for the Baton Rouge 

nonattainment area in 2005-2007 and it helped the agency to reduce ozone precursors and reduce ozone 

level. This is an observation-based, episode-oriented analysis, and could lead to prompt actions. It can 

help validate (or provide feedback to) ozone forecast. It keeps PAMS information in the forefront and 

relevant in the effort to attain the ozone standard. 

Seasonal or Annual Data Analysis: At the end of each ozone season (or end of each year), a data 

analysis should be performed to review the data collected during the season (or year). More data 

analysis tools should be used in the End of Season Analysis than the Daily Data Analysis described 

above. This analysis should reveal more information by examining the data set as a whole. It should also 

include previous years’ data for trending. Most of the data analysis tools included in the 1997 Workbook 

were designed for this type of long-term data analysis. This analysis should be done promptly at the end 

of an ozone season (or at least at the end of a calendar year) to keep it relevant and applicable to the 

coming ozone season.

Charge Question 22 - How should any recommended data analyses be implemented? Should these 

analyses be conducted at the state, regional, or national level?

Response: The most important objective of the PAMS program is to help ozone nonattainment areas to 

achieve attainment. The data analyses discussed above (Charge Question 21) should be conducted at the 

area consistent with the nonattainment area where the PAMS sites are designed to cover. The data 

analysis should be done by the agency or the regional planning organization responsible for the ozone 

nonattainment area. Unless two nonattainment areas are adjacent, the PAMS analysis for them should be 

performed separately. Neighboring agencies’ cooperation should be encouraged. EPA may conduct 

some data analysis at a high level covering regional or national trend. 

The discussions for Charge Question 21 have touched on some implementation issues. In addition to 

generating high quality PAMS data, completion of PAMS data analysis should be part of PAMS annual 

funding requirements. Each monitoring agency should demonstrate how the PAMS data is used in the 

ozone attainment effort. EPA should consider annual workshop or symposium in winter or early spring 

to facilitate exchange of ideas/methods for data analysis among PAMS monitoring agencies and to 

demonstrate how PAMS data is used to help achieve ozone attainment.

Charge Question 23 - Should more or less of the PAMS funding be allocated to data analysis?

Response: The EPA White Paper for this review states that the current PAMS funding level is $14 

million per year and EPA guidance is to use 25% of the funding for data analysis. According to PAMS 

website, there are 24 areas under the PAMS program. On average each area should receive about 

$583,333 for PAMS operations, of which $145,833 should be used for data analysis. The 25% for data 
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analysis seems adequate if this amount is actually used for data analysis. This does not seem to be the 

case. PAMS is more of an investigative program than a compliance program or research program. The 

PAMS program should include sufficient and meaningful data analysis to provide information that can 

be used to solve the ozone attainment problem. 

Allocation of fund for data analysis does not need to be proportional to the number of sites in each area. 

The level of effort to perform the same types of data analysis for an area with 2 PAMS sites is going to 

be more than a half of that for an area with 4 PAMS sites. In other words, the increment cost for adding 

one more site in an analysis will be less than the cost of performing the analysis for the first site. 

Although the same principle of economy of scale applies to sampling and chemical analysis aspect of 

PAMS operation, the effect for data analysis is more noticeable.

EPA should consider setting aside some data analysis fund at the national level and use this fund to: 

• Develop useful data analysis tools in the PAMS data analysis tool box, including guidance 

documents, data analysis methods, online data analysis tools, and computer programs to 

automate the process of monitoring data analysis and visualization.

• Provide data analysis training and organize annual PAMS data analysis workshop or symposium.

1. Bibliography

Carter, W. P. (2009). Updated Maximum Incremental Reactivity Scale and Hydrocarbon Bin 

Reactivities for Regulatory Applications. Sacramento, CA: California Air Resources Board, Contract 07-

339.

Providence Engineering & Environmental Group LLC. 2010. Analysis of PAMS Data 1994-2007. Fresno, 

California: San Joaquin Valley Air Pollution Control District, Contract 08-10-07 (the report is available 

online - http://www.providenceeng.com/P/Files/othertechnicalinfo/455-002-

001ER%20Final%20Report%20Narrative.pdf).

Zhou, L., Zeng, Y., Hazlett, P., & Matherne, V. 2007. Ambient air monitoring with Auto-gas 

chromatography running in trigger mode. Analytica Chimica Acta 596(1):156-63.
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