Atmospheric dispersion modelling provides a mathematical description of the behaviour of pollutants in the air for a specific period of time. This is an essential tool used by government agencies, industry and consultants for air quality assessment, especially when decisions regarding approvals and permits have to be made.
The dispersion models are very often the only economically viable methods that can be used to understand the interaction of existing or future pollution emission sources with meteorology, topography and air quality at specific locations and times.
Some of the dispersion models are more complex than others and all models require inputs (emissions, meteorology and topography). If these inputs are of poor quality, then the model output will also be of poor quality.
It is the responsibility of professionals conducting modelling to make sure that the appropriate model is selected for a given situation, that all the inputs have been checked for completeness and accuracy, and that testing has been done to ensure that the model has been used correctly.
Air dispersion models have their limitations. One cannot expect one model to be suitable for use in all geophysical, atmospheric and source situations. After all, air quality modelling relies on the physics and chemistry of dispersion and reactivity of pollutants in the atmosphere and mathematical formulations of the physics and chemistry being translated into computer programs carrying out the corresponding calculations. Interpreting the output of modelling and assessing how much confidence should be placed in the results involves considerable expertise and experience which are critically important to achieving useful results.
Modelling is an integral part of air quality management in Tasmania and it is used to predict the potential impact of pollutant emissions to the atmosphere from existing and proposed developments as well as a tool to fine-tune the existing or proposed project designs to minimise their potential impact on air quality.
The State's Environment Protection Policy (Air Quality) 2004 Clause 14 requires modelling of air pollutant dispersion where it is likely that air quality problems may occur. This modelling is usually carried out by specialised consultants with advice from EPA Tasmania.
Several atmospheric dispersion models have been approved by the EPA Director for use in Tasmania. Consultants should contact the EPA Tasmania modelling specialists for advice on the applicability of individual models for use in specific situations or guidance on individual model settings prior to commencement of modelling.
Atmospheric Dispersion Modelling Guidelines provide the EPA Tasmania requirements for atmospheric dispersion modelling conducted for projects located in Tasmania.
Atmospheric Dispersion Modelling Guidelines (131Kb)