EPA Research Partner Support Story: Reducing harmful air pollutants
Partners: California Air Resources Board, Georgia Environmental Protection Division, Maryland Department of the Environment, New Jersey Department of Environmental Protection, New York State Department of Environmental Conservation, North Carolina Department of Environmental Quality, Utah Department of Environmental Conservation, Virginia Department of Environmental Quality, San Joaquim Valley Unified Pollution Control District, South Coast Air Quality Management District
Challenge: Need for effective strategies to reduce harmful air pollutants
Resource: EPA’s Community Multiscale Air Quality (CMAQ) Modeling System
Project Period: 2005 – Present
For more than 25 years, EPA and states have been using EPA’s Community Multiscale Air Quality (CMAQ) Modeling System, a powerful computational tool for air quality management. CMAQ simultaneously models multiple air pollutants, including ozone, particulate matter, and a variety of air toxics to help air quality managers determine the best air quality management scenarios for their states and communities.
"Maryland has made dramatic progress over the past 10 years in reducing ozone and fine particle pollution. We have invested heavily into research and modeling and this investment has been one of the reasons we have been successful. The CMAQ photochemical model has been the key tool we have used to design and refine control strategies. It has helped us find least cost solutions to reduce ozone and fine particle pollution." – ECOS Executive Director Ben Grumbles (former Secretary, Maryland Department of the Environment)
State agencies that control air pollution use CMAQ to develop and assess implementation actions needed to attain National Ambient Air Quality Standards (NAAQS) mandated by the Clean Air Act. States use the tool to identify sources of air quality problems and to assist in the design of effective strategies to reduce harmful air pollutants. Using data about land use, meteorology, and emissions, CMAQ provides detailed information about the concentrations of air pollutants in a given area for any specified emissions or air quality scenario. With information generated by CMAQ, states are able to examine the estimated impacts of different air quality policies.
The National Weather Service also uses the model to produce air quality forecasts twice daily, and the Centers for Disease Control and Prevention use CMAQ data in two community-focused tools that allow users to access county-specific air quality information on pollutants, such as ozone and particulate matter.
The CMAQ modeling system is publicly available, undergoes rigorous scientific peer-review and is used worldwide (in over 125 countries) for air quality assessments and research. The system brings together three kinds of models including meteorological models to represent atmospheric and weather activities; emission models to represent man-made and naturally occurring contributions to the atmosphere; and an air chemistry-transport model to predict the atmospheric fate of air pollutants under varying conditions. The newest version of the model (CMAQ 5.5) was released in October 2024.