Air dispersion modeling uses information about sources and meteorological conditions to calculate how a pollutant moves through the atmosphere and what the pollutant concentration is at specific points. Based on inputs of meteorological data and source information like emission rates and stack height, these models are designed to characterize primary pollutants that are emitted directly into the atmosphere and, in some cases, secondary pollutants that are formed as a result of complex chemical reactions within the atmosphere. These models are important to our air quality management system because they are widely used by agencies tasked with controlling air pollution to both identify source contributions to air quality problems and assist in the design of effective strategies to reduce harmful air pollutants.

For example, air quality models can be used during the permitting process to verify that a new source will not exceed ambient air quality standards or, if necessary, determine appropriate additional control requirements. In addition, air quality models can also be used to predict future pollutant concentrations from multiple sources after the implementation of a new regulatory program, in order to estimate the effectiveness of the program in reducing harmful exposures to humans and the environment.

Ecology development bureau in Dispersion modeling uses mathematical formulations to characterize the atmospheric processes that disperse a pollutant emitted by a source. Based on emissions and meteorological inputs, a dispersion model can be used to predict concentrations at selected downwind receptor locations. These air quality models are used to determine compliance with National Ambient Air Quality Standards (NAAQS), and other regulatory requirements such as New Source Review (NSR) and Prevention of Significant Deterioration (PSD) regulations.

With Ecology Development Bureau you can:

• Define the nature of the hazards associated with the air dispersion of hazardous chemicals.
• Discuss the interaction of air dispersion of hazardous chemicals with the natural environment.
• Discuss the goals and objectives of air dispersion modeling of hazardous chemicals, specific to the intended user.
• Outline the capabilities of the model and discuss data requirements.
• Review available results and discuss importance to different user groups.
• Discuss the application of air dispersion model results for both planning and emergency management operations.