ISCST3 (Industrial Source Complex Short Term Version 3) is a widely used air dispersion model developed by the U.S. Environmental Protection Agency (EPA). It is designed to estimate the concentration of pollutants in the air resulting from industrial emissions over short time periods (typically less than 24 hours). ISCST3 is primarily used for assessing air quality impacts from point sources, such as smokestacks, and helps in regulatory decisions related to air pollution control.
Key features of ISCST3 include:
- Short-Term Modeling: The model calculates pollutant concentrations over short time periods, typically hourly or for up to a few days. It’s useful for evaluating the impact of pollutants like nitrogen oxides, sulfur dioxide, and particulate matter.
- Terrain and Meteorological Data: ISCST3 can take into account complex terrain, which allows for more accurate predictions in regions with hills or valleys. It also uses meteorological data to assess dispersion based on factors such as wind speed, wind direction, and atmospheric stability.
- Source Configurations: ISCST3 can handle both point sources (such as a stack or vent), area sources, and volume sources. It can model emissions from sources at varying heights and configurations.
- Hourly and Seasonal Variability: The model incorporates hourly variability of wind direction, speed, and atmospheric conditions to provide detailed predictions of pollutant concentrations.
- Complex Dispersion Algorithms: It uses Gaussian plume dispersion algorithms to calculate how pollutants move in the atmosphere under different conditions.
- Regulatory Compliance: ISCST3 is often used by industries to demonstrate compliance with air quality standards set by the EPA, such as the National Ambient Air Quality Standards (NAAQS).
While ISCST3 is widely used, the model has been somewhat superseded by newer models like AERMOD, which offers more advanced capabilities for modeling air quality in both complex and simpler environments. However, ISCST3 is still useful in many regulatory and permitting scenarios.