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Science Products
This page provides information on selected scientific papers, reports, and other references produced by researchers in the Clean Air Research Program.
Research papers are available from published journals or through PubMed, a service of the U.S. National Library of Medicine that includes over 16 million citations from MEDLINE and other life science journals for biomedical articles.
A list of the Clean Air Research Program's most highly cited publications (PDF) (27 pp, 274K) demonstrates the program's impact on advancing human health research.
To obtain copies of ORD (and other EPA) documents:
- National Service Center for Environmental Publications (NSCEP): NSCEP is EPA's central repository of all EPA documents with over 7,000 titles available in paper or electronic form.NSCEP also produces the EPA National Publications Catalog which is available on their web site.
- National Environmental Publications Internet Site (NEPIS): NSPIS is EPA's largest electronic documents site which allows you to search view and print, including full images of all original pages and full-text, from a collection of over 10,000 archival and current documents. This collection may include documents that are no longer available in print form. ORD publications are listed at "Publication Title List - 600 Series."
Community Multi-Scale Air Quality (CMAQ) Model
CMAQ supports the environmental management community's ability to evaluate the impact of air quality management practices for multiple pollutants at multiple scales and the scientist's ability to better probe, understand, and simulate chemical and physical interactions in the atmosphere. The initial Eta-CMAQ air quality forecast system was designed and implemented through a partnership between EPA and NOAA. CMAQ was selected by EPA for Clean Air Interstate Rule (CAIR) rulemaking for fine particles (PM2.5).
More information on Community Multiscale Air Quality (CMAQ)
Atmospheric Chemistry Used to Refine Models
Laboratory and field studies have made substantial gains in defining atmospheric chemistries that have achieved a better understanding of ambient air processes and assisted with refining the predictive accuracy of complex multi-pollutant atmospheric models like CMAQ. Each year, one or more upgrades of CMAQ are release for use by states and other clients and for use by researchers.
More information on Community Multiscale Air Quality (CMAQ)
SPECIATE Database to Support Inventory Development, Source Apportionment, and Air Quality Modeling
The SPECIATE database is an important EPA product which serves as the repository for emission profiles by source category. The profiles contain volatile organic compounds (VOC) and particulate matter (PM) species. The VOC species are grouped into reactivity classes to support ozone air quality modeling. The PM species contain information on size and composition and are used to support PM and visibility air quality modeling. The database also has supported air toxic assessments and is integral to source receptor modeling applications. The database is posted on the Clearing House for Inventories and Emission Factors (CHIEF) Website.
More information on SPECIATE Software Version 4.0
Technology Used to Find and Characterize Air Pollutants
Laser-based time-of-flight instruments provide real-time analyses of trace organics, including aromatics and poly aromatic hydrocarbons (PAHs), in dilute vehicle exhaust and fugitive emissions. Engine emission characterizations from various vehicle types, such as idling versus moving diesel school buses, have likewise undergone detailed study by the Clean Air Research Program not only of mass emissions but chemical speciation. Other sources not well-characterized in the context of their relative impact on ambient air -- ranging from dispersed seasonal wildfires to point sources like airports -- have begun to be characterized using analogous advanced optical and prototype satellite-based technologies. The data improves and updates emission inventory databases maintained by EPA which are used in atmospheric models.
Optical Remote Technologies Identify Emissions Sources
The Clean Air Research Program has significantly updated and improved understanding of many poorly-characterized sources of air pollutants. For example, diffuse sources are particularly problematic for states because, unlike point sources, where pollutants can be measured by placing a measurement device in one or multiple stacks, emissions occur over wide areas often with varying topography. New optical remote techniques have been applied to generate new emissions data for varying types of sources from biomass burning to livestock waste ponds. Optical remote methods for precursor gases such as ammonia are not only important for general air hygiene but allow refinements in atmospheric models where ammonia is a major assumption in aerosol chemistry (e.g., acidity). The data improves and updates emission inventory databases maintained by EPA which are used in atmospheric models.
More information on Technology Transfer Network Emission Measurement Center
Detroit Study Revealing Sources of Pollution Impacting Residents
A large, multi-year, multi-season exposure study in Detroit called DEARS is providing the most detailed database to date on the sources of air pollution that are resulting in exposure to residents, regionally, locally, and indoors across the Detroit urban landscape. New speciation methodologies for organics have been developed and are yielding data refining fine particulate matter (PM2.5) composition and its source links. These advancements will assist with improvements of various atmospheric models.
Related health studies in asthmatic children and adults with cardiovascular disease in the Detroit area is yielding refined risk estimates and better source attribution. The research is expected to improve assessment of mitigation strategies to reduce the health impact of air pollution.
More information on Detroit Exposure and Aerosol Research Study (DEARS)
Optical Remote Sensing Source Measurement Methods
Vertical and Horizontal Radial Plume Mapping (VRPM and HRPM) are new analytical methods that allow for rapid and direct measurement of air pollutant emissions from area sources. VRPM and HRPM use open-path optical measurements to determine path-averaged pollutant concentrations near emission sources.
Open-path techniques provide near real-time, in-situ measurements and can be configured along multiple paths, allowing for the assessment of concentration gradients. The multi-path pollutant concentration data generated by the open-path instrument are combined with wind speed and wind direction information and processed with the VRPM and HRPM algorithms to yield a mass emission flux for the source and give area source concentration profiles. The HRPM algorithm can be used to generate concentration profiles for area sources.
The method has undergone verification studies and has been reduced to protocol form in EPA Test Method OTM 10, entitled Optical Remote Sensing for Emission Characterization from Non-point Sources, 2006, US EPA Technology Transfer Network Emission Measurement Center.
More information on Technology Transfer Network Emission Measurement Center
On-Road Laboratory to Measure Mobile Source Emissions
An on-road laboratory known as the Diesel Emissions Aerosol Laboratory (DEAL) uses state-of-the-art measurement methods to measure fine PM from heavy duty diesel trucks and other sources such as aircraft. New emission factors and chemical source profiles
are being generated using this facility for use in receptor modeling and as inputs to other mobile source emissions models. The results using this technique are expected to provide updated data that can be used to assess more accurately the impact of emissions from heavy-duty diesel trucks and off-road sources (e.g. aircraft) on ambient air quality.
More information on Heavy Duty Diesel Trucks
Receptor models and source apportionment methods
The Clean Air Research Program develops, evaluates, and applies methods and models that can be used to improve our understanding of how sources impact residential outdoor, indoor, and personal concentrations and, in particular, to identify ambient source contributions such as motor vehicles and power plants. This includes analyses of data and modeling results to determine which sampling methods and modeling improvements likely will have the most significant impact in reducing uncertainties in source apportionment analyses. Using insights from these analyses, organic analytical methods are refined and evaluated. A Stochastic Human Exposure and Dose Simulation (SHEDS) model for PM -- EPA SHEDS-PM 2.0 -- estimates the range in PM exposure and/or intake-dose across a population of interest, and percentage of estimated exposures above a certain level. The model includes a user-friendly interface that allows the user to define the model run scenario and input data, as well as to analyze and display the results.
PM Methods Development
Federal Reference Methods (FRM) are developed to measure pollutants regulated under the Clean Air Act. The Clean Air Research Program established a FRM for fine particles (PM2.5) in 1998 which has served to determine compliance with the federally mandated and state / tribal implementation of the National Ambient Air Quality Standards. In 2005, the coarse (PM10-2.5) particle standard was promulgated for preliminary determination of ambient coarse levels at selected monitoring sites nationwide. In conjunction with the traditional integrated, filter-based samplers, the continuous samplers are being developed to provide state, local, and tribal monitoring organizations with advanced tools to better meet multiple monitoring objectives.
More information:
Methods of monitoring criteria pollutants
EPA Board of Scientific Counselors Spring 2005 review of particulate matter research program
Code of Federal Regulations: National primary and secondary ambient air quality standards for particulate matter and other pollutants