Air dispersion modelling in response to regulations is the cornerstone of many projects completed by SENES and involves using various computer programs to mimic the way the atmosphere disperses pollutants. A wide variety of approved and state-of-the-art models are used depending on the situation that is to be modelled. SENES has undertaken many studies comparing the results of different models and validating model results with field studies.

The dispersion of airborne pollutants is simulated using regulatory models developed by the US Environmental Protection Agency, the Ontario Ministry of Environment and others:

Ontario Regulation 346 Model - historical Certificates of Approval (Air) model
ISC3 and ISC-Prime (SCREEN 3) - regulatory models used globally
AERMOD - state-of-the-art dispersion model
CALMET/CALPUFF/CALGRID - sophisticated short/long range transport model

Modelling of tropospheric ozone, acid deposition, visibility, and fine particles in the atmosphere are related to complex interactions of atmospheric chemistry and physics requiring a complicated model that can handle these interactions on urban to regional scale. The MODELS-3 framework with MM5 as meteorological driver, SMOKE as emission preprocessor and Community Multi-scale Air Quality Model (CMAQ) as air dispersion model with photochemistry is currently the model system of choice in this area.