Air dispersion modeling, also known as atmospheric dispersion modeling, atmospheric diffusion modeling, air quality modeling, and air pollution dispersion modeling, is the mathematical simulation of how air pollutants (plum) disperse in the ambient atmosphere. Air dispersion modeling is performed using computer programs that solve the mathematical equations and algorithms that simulate the plum’s dispersion. The dispersion models are used to estimate or to predict the downwind concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases.
Air dispersion modeling predicts the rate of spread of the plum, and the consequent decrease in mean concentration of the air pollutants. The model must be able to predict rates of diffusion based on measurable meteorological variables such as wind speed, atmospheric turbulence, ground elevations and terrain, and thermodynamic effects.
Air dispersion modeling is important not only to governmental agencies tasked with protecting and managing the ambient air quality, but also to industrial facilities that are regulated under the Clean Air Act (CAA). Air dispersion modeling is typically used to determine whether new or existing industrial facilities meet compliance with the National Ambient Air Quality Standards (NAAQS). Air dispersion modeling is also used in environmental impact assessments, risk analysis, source apportionment studies, the design of pollution control and control strategies, and is used by public safety and emergency management personnel for emergency planning of accidental chemical releases.
The results of air modeling, using worst case accidental release source terms and meteorological conditions, can delineate the vertical and horizontal extent of a plum, air pollutant concentrations and plum movement, which can be used to determine preventive and protective actions. This type of consequence assessment or emergency planning is used in the development of emergency management and response plans.
Air dispersion modeling services provided by Total:
- Ambient air quality
- Air permit application support
- Accidental release analyses and off-site consequence analyses required by RMP Section 112(r)
- “What-if ” analyses to determine the effects of potential operational changes
- Offshore modeling to meet Mining and Minerals Management Service requirements
- Off-site impact and deposition studies to support litigation activities
Total Environmental & Safety, LLC (Total) applies innovative methodologies that avoid overly conservative results while meeting regulatory requirements. With extensive knowledge of state and federal modeling requirements, Total’s unique insight into air dispersion modeling allows us to develop innovative modeling strategies to increase operational flexibility while demonstrating compliance with air quality standards.