Air Quality Analysis Updated: July, 2005

Two types of air quality analysis are being performed in support of the Draft O’Hare Modernization Environmental Impact Statement (EIS) – emission inventories and dispersion analysis.  The emission inventories provide an indication of the change in total air pollutant and pollutant precursor emissions with implementation of the Proposed Project.  The dispersion analysis evaluates both macroscale and microscale effects.  The macroscale analysis provides an indication of the change in concentrations of carbon monoxide, nitrogen dioxide, sulfur oxides and particulate matter on and in the vicinity of the Airport while the microscale analysis evaluates concentrations of carbon monoxide immediately adjacent to intersections/interchanges within the study area.

The emission inventories and the macroscale dispersion analysis were prepared using the following Federal Aviation Administration (FAA) and US Environmental Protection Agency (USEPA) computer models which are commercially available:

The FAA-required EDMS is a model designed to assess the air quality impacts of proposed airport development projects.  The USEPA’s MOBILE model is a tool for predicting emissions of hydrocarbons, carbon monoxide, oxides of nitrogen, carbon dioxide, and particulate matter from cars, trucks, and motorcycles.  The USEPA’s CAL3QHC model is a carbon monoxide model that includes a traffic model to calculate delays and queues that occur at signalized intersections.  Finally, the USEPA’s NONROAD model is used to estimate air pollution inventories for nonroad vehicles, equipment, and engines.

The computer models are not available on this website.  However, links have been provided where the models may be ordered and/or downloaded.  The computer modeling is being performed by Environmental Science Associates, one of the Third Party Consultants (TPCs) supporting the FAA in the preparation of the EIS.

As the draft methodologies, project files, and modeling results of the air quality analysis become available, the FAA will post these components.  However, please be advised that the data continues to be reviewed by the FAA and is subject to change.

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