The International State of the Science Workshop on Organic Speciation
in Atmospheric Aerosol Research (April 5-7, 2004 in Las Vegas,
Nevada at the Desert Research Institute) is being developed to
bring together diverse members of the research community in hopes
of evaluating the state of the science and identifying information
gaps with regard to characterization of organic aerosols. The
workshop is a step in working to achieve the goals of the Atmospheric
Particulate Exchange (APACE) series of symposia. Particular emphasis
is placed on identifying the needs of air pollution researchers
in complementary disciplines, such as ambient air modeling (particularly
source-receptor), health hazard research, visibility, and climate.
Workshop discussions will emphasize the following general questions:
How do we define semi-volatile and particle-associated organic
2. What are the conventional and emerging methods for collecting
and analyzing organic carbonaceous aerosols, and how do we assess
those methods for their ability to fulfill the needs of public
health, climate, and modeling?
3. How do we assess accuracy and precision, and what criteria
should be met for regulatory or other purposes?
workshop aspires to summarize current knowledge, articulate needs
for further research, and document where the greatest capacity
for advancement exists. One goal is to characterize the state
of the science and needs across disciplines through a combination
of lectures, open-forum discussions, and focus groups.
workshop findings and recommendations on the state of the science
will be summarized in a peer-reviewed article to be prepared by
pre-selected participants. Findings and recommendations will also
be disseminated to non-workshop participants on the email list
with a request for input in order to further develop an account
of the state of the science that accurately reflects current research
reality and future potential. The results will be disseminated
to interested and affected research and sponsor communities.
out to key experts and sponsoring organizations through a non-competitive,
cooperative dialogue to identify new capacities in organic aerosols
speciation research is a primary purpose of this third workshop
in an on-going series of yearly workshops. The workshops are planned
and conducted by a network of researchers, sponsors, support organizations,
and individuals referred to as the Atmospheric PArticulate Carbon
Organic carbon comprises a large fraction of the PM10 and PM2.5
ambient aerosol mass. In many areas, organic carbon is predominant
over elemental carbon and other inorganic constituents. The health
effect of fine PM has been postulated to be associated with the
organic fraction of PM. Yet, the composition of organic aerosol
is still not well-defined. Many uncertainties remain concerning
the presence of specific compounds, especially the composition
of more polar, water soluble and bioorganic fractions, which is
not known. There is a need for defining the current state of knowledge
and what are the remaining gaps that need to be addressed.
A. Clarification of Organic Aerosol Terminology
Uncertainty exists in defining commonly used terminology, such
as semi-volatile organic compounds (SVOC), volatile organic compounds
(VOC), particle-associated organic compounds.
1: Document agreement, where it is possible, among leading
researchers in the field of organic aerosols on the definition
of these terms. In addition, new terms may be derived to more
explicitly characterize the molecular structure and/or classes
of organic aerosol species present in the atmosphere.
Identify and Explore Limitations of Current Organic Aerosol Sampling
Due to the numerous types of chemical species comprising organic
aerosols, with their inherently different physical properties,
accurate sampling of organic aerosols is a very challenging task.
First, traditional organic sampling approaches are prone to artifacts,
leading to ambiguous operational definitions of either particle
bound or vapor phase semi-volatile organic compounds. Other artifacts
may exist because of the presence of organic material in the background
of sample collection devices or sample processing procedures.
Sampling techniques must take into consideration the sensitivity
of the end analysis, and often the amount of material required
for analysis or trace components is a limiting factor.
2: Address sampling difficulties such as the condensability
(i.e., positive artifacts) and volatility of organic species (i.e.,
negative artifacts), and identify current sampling techniques
(including emerging techniques) and needs for specific types of
organic aerosols depending on their physical and chemical attributes.
C. Identify and Explore Limitations of Current Technology
for Analyzing Organic Aerosols
A difficult problem in the study of organic aerosols is the lack
of reliable chemical analysis methods to distinguish the hundreds
of compounds that exist in air. Two important components of the
analysis are: 1) how is the sample processed or introduced to
an analyzer, and: 2) what is the analysis technique and how is
it calibrated? Conventional organic analysis relies on solvent
extraction or thermal desorption of material collected on filters
or sorbents, and analysis by gas-liquid or liquid chromatography
interfaced to a mass spectrometer or other detection device. Current
analysis techniques are only able to account for a small fraction
of the individual organic species that make-up the bulk of organic
material. Of the compounds that have been identified and characterized,
there are few criteria for evaluating the accuracy and precision
among different techniques and laboratories.
3: Assess our current knowledge of sample introduction
and analysis techniques, with emphasis on current state of the
science and knowledge gaps, particularly with respect to challenges
associated with compounds in different chemical classes.
Objective 4: Assess promising techniques for
measuring the unidentified component of organic carbon. Do macromolecular
analysis techniques help fill in the knowledge gap? What macromolecular
analysis techniques, or other techniques aimed at sorting out
the composition of total organic material exist?
Goal 5. Define criteria and needs for assessing and improving
accuracy of organic analysis techniques, with consideration of
both research and regulatory communities.
Identify and Explore Organic Aerosol Speciation Needs of Related
Disciplines (i.e. Modeling, Public Health, Outdoor and Indoor
Arguably, the major portion of the push to analyze several classes
of different organic compounds and compound classes in air has
been driven by the needs of the source apportionment community
to develop chemical signatures that allow accurate attribution
of carbonaceous sources. Other communities, such as health hazard
and to some extent climate researchers, have benefited from this
increased knowledge in the composition of ambient air and sources.
It is currently unclear if the needs of any of those communities
have been met or exceeded, and while communication between the
analytical chemistry community and these communities has improved,
there has not been a summary of research needs of these communities
assembled in a large interdisciplinary forum.
6: Review and define the organic speciation needs of
the modeling, health and climate communities.
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