Tropospheric air above the mixed surface layer.
Air in the upper troposphere or lower stratosphere.
Therefore, the ventilation supply air can be contaminated by background urban pollution and by emissions from local airport sources when the aircraft is on the ground. Urban air pollution is also encountered shortly after takeoff and before landing; however, these periods are usually small fractions of an entire flight. Finally, when flying in the upper troposphere or lower stratosphere, an aircraft can encounter high ozone (O3) concentrations. The issues noted are explored in the following sections.
Most airports are near large metropolitan areas, where pollution can exceed health-based standards. For example, in 1999, 105 million U.S. residents lived in areas that were designated “nonattainment” with respect to at least one of the criteria pollutants (EPA 2000). On a population-weighted basis, the most serious problems were posed by O3, 90 million residents; particulate matter (PM), 30 million residents; and carbon monoxide (CO), 30 million residents. In addition to urban air pollution, substantial amounts of combustion-generated pollutants are emitted on the ground at airports by, for example, aircraft jet engines and diesel-powered service vehicles. Because emissions at airports are important contributors to urban and regional air pollution, modeling and measurement programs have been established to measure the emissions and the resulting concentrations (Moss and Segal 1994). Some of the information is summarized in the following paragraphs, but it does not appear to have been used to investigate the effect of emissions at airports on air quality in passenger cabins of aircraft.
During the middle 1980s, the Emissions and Dispersion Modeling System (EDMS) was developed to assess air-quality effects of proposed airport development projects (Moss and Segal 1994). It was developed by the Federal Aviation Administration (FAA) in cooperation with the U.S. Air Force and is supported as a Windows-based simulation tool.1 Specifically, the EDMS is
Background information on the EDMS tool is available at http://www.aee.faa.gov/aee-100/aee-120/edms/banner.htm where it can be purchased.