In accordance with the Clean Air Act, modeling analysis is required for the purpose of demonstrating the future attainment and continued maintenance of federal air quality standards. Modeling is also used to evaluate the effectiveness of pollution control measures, and to evaluate whether transportation plans and projects conform with State Implementation Plans. Regional air quality modeling is conducted by MAG to predict levels of pollutants such as ozone (O3) and particulate matter (PM-10 and PM-2.5) based on principles of atmospheric physics, and results are made public as part of the State Implementation Plans.
The modeling process has several steps, beginning with emissions inventory development and atmospheric modeling of weather conditions. These provide inputs to photochemical models which predict the movement and formation of pollutants throughout the region. Model output is validated through data analysis involving observations from air quality monitors and other ground-based instruments, upper air weather balloons, and space-based measurements from satellite instruments. Data analysis also provides insight into the trends and patterns of pollution in our region, which enables effective air quality planning.