Fast, pre-computed modeling blocks for facilitating timely exposure assessment
S. Isukapalli, P.G. Georgopoulos
Environmental and Occupational Health Sciences Institute, UMDNJ - R.W. Johnson Medical School and Rutgers University, Piscataway, NJ
The assessment of population exposures to atmospheric pollutants involves several component tasks: obtaining ambient outdoor concentrations using either air quality modeling or air quality monitoring data, obtaining local scale (typically census-tract level) outdoor concentration fields via interpolation, generating virtual individuals based on appropriate demographic and socio-economic attributes in the study region, developing representative activity patterns for simulated individuals, calculating microenvironmental concentrations for each activity event, calculating exposures, and calculating appropriate doses based on physiological characteristics of simulated individuals. This process may require significant computational resources when simulations are performed for a large geographic region for long time periods, involving hundreds of thousands of virtual individuals. When multiple comparative simulations are used to study the same scenario, only some steps need to be repeated. For example, comparing multiple emission control strategies require changing only the concentration terms, while the virtual individuals and their activity patterns remain unchanged. Current systems for such studies require repetition of all the tasks, leading to three issues: (a) significant computational resources are needed for repeating already computed steps, (b) additional variability is introduced across different model runs due to the inherent stochastic sampling, and (c) users need to understand the entire system instead of the just the single step that they need to run frequently (e.g. calculation of outdoor concentrations). This effort presents an approach for modularizing the exposure assessment steps and introduces techniques for developing "pre-computed" modeling blocks that can be reused. A case study demonstrating this approach for assessing exposures and doses to air pollutants in the urban Philadelphia , PA area is presented.
This work is funded in part by the USEPA under Cooperative Agreement #EPAR-827033 to the EOHSI. Viewpoints expressed here are the responsibility of the authors and do not necessarily reflect the views of the USEPA or its contractors.