Air plume models

In 2005, Bullman et al. (2005) reported the results of a mortality study of troops exposed to chemical warfare agents based on the air plume models that were developed after the detonation. The cause-specific mortality of 100,487 exposed veterans was compared with that of 224,480 unexposed US Army Gulf War veterans. The risks for most disease-related mortality were similar for exposed and unexposed veterans. However, exposed veterans had an increased risk of brain cancer deaths (relative risk= 1.94 95% CI= 1.12, 3.34). The risk of brain cancer death was larger among those exposed 2 or more days than those exposed 1 day when both were compared separately to all unexposed veterans. 

PRACTICAL USES OF AIR PLUME MODELING IN CHEMICAL EMERGENCIES... 

Air plume modeling can help in the process of deciding whether to evacuate or remain in place, but the modeling should not replace common sense. An appropriate model is used to predict the maximum outdoor concentration and cloud duration at the building location. The assumption is usually made that the air recirculation rate within the building is ample but the building air intake is closed (windows closed). The simplest calculation predicts a concentration C, within the building after time t (t = outside toxic plume cloud duration in hours) ... 

Cramer, H. E., Improved techniques for modeling the dispersion of tall stack plumes. "Proceedings of the Seventh International Technical Meeting on Air Pollution Modeling and Its Application." North Atlantic Treaty Organization Committee on Challenges of Modern Society. Pub. No. 51. Brussels, 1976. (National Technical Information Service PB-270 799.)... 

Air Pollution Dispersion Application of air dispersion modeling principles and EPA tools to assessing environmental impacts from stack and area releases of pollutants Dispersion theory Gaussian plume model Ground-level concentrations Worst case scenarios Air quality impact assessments Stationary source emissions... 

Software for dispersion modeling uses Gaussian plume model. Phe system calculates concentration or deposition values for inputed time periods. May be used in conjunction with "Breeze Air."... 

Denser-than-air puff or plume Britter and McQuaid use the ratio of the source duration to the travel time to distinguish between plumes and puffs with a slightly different definition of travel time tt = xe/(0.4ur). The release can be considered a plume if ts > tt, where ts is the source time scale defined above, and the release can be considered a puff if ts < tJ4. For tt/4 plume models are entirely appropriate the predicted concentration is considered the largest of the puff and plume predictions. 

Pheromone propagation by wind depends on the release rate of the pheromone (or any other odor) and air movements (turbulent dispersion). In wind, the turbulent diffusivity overwhelms the diffusion properties of a volatile compound or mixture itself. Diffusion properties are now properties of wind structure and boundary surfaces, and preferably termed dispersion coefficients. Two models have dominated the discussion of insect pheromone propagation. These are the time-average model (Sutton, 1953) and the Gaussian plume model. 

The box model is closely related to the more complex airshed models described below in that it is based on the conservation of mass equation and includes chemical submodels that represent the chemistry more accurately than many plume models, for example. However, it is less complex and hence requires less computation time. It has the additional advantage that it does not require the detailed emissions, meteorological, and air quality data needed for input and validation of the airshed models. However, the resulting predictions are... 

Gaussian plume model for air pollution [ATMOSPHERIC MODELING] (Vol 3)... 

One classic Gaussian plume model for smokestack emissions is the Pas-quill-Gifford model, which applies for steady emissions of a chemical over relatively level terrain. If no chemical sinks exist in the air (i.e., no reactions are degrading the chemical) and if there is an unlimited mixing height (i.e., no atmospheric inversion exists, and the plume can be mixed upward indefinitely), the Pasquill- Gifford model can be expressed in the form... 

One commonly used suite of models that is based on Gaussian plume modeling is the Industrial Source Complex (ISC) Dispersion Models (US EPA, 1995). This suite includes both a short-term model (ISCST), which calculates the hourly air pollutant concentrations in an area surrounding a source, as well as a long-term model (ISCLT), which calculates the average air pollutant concentrations over a year or longer. ISCLT uses meteorological data summarized by frequency for 16 radial sectors (22.5° each) this data format is referred to as a stability array (STAR). Within each sector of STAR, joint frequencies of wind direction, wind speed, and atmospheric stability class are provided. 

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