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Characterization of Emissions from Commercial Aircraft Engines during the Aircraft Particle Emissions eXperiment (APEX) 1 to 3 (EPA/600/R-09/130) October 2009

Cover photo of Commercial Aircraft Engine

The fine particulate matter emissions from aircraft operations at large airports located in areas of the U. S. designated as non-attainment for the National Ambient Air Quality Standard for PM-2.5 are of major environmental concern. PM emissions data for commercial aircraft engines is. To improve aircraft PM emissions data, the Aircraft Particle Emissions eXperiment (APEX) was organized in 2003. The objectives of the three APEX sampling campaigns (APEX-1, -2, and -3) were to update and improve emission factors (indices) and chemical source profiles for aircraft-generated fine PM and, if possible, to assess the effect of fuel properties and engine operating conditions on PM formation. During APEX-1, -2 and -3, ground level measurements were conducted by EPA in the engine exhaust plume, primarily at a single point located a distance of 30 m behind the engine exit. A total of 24 tests were conducted during the three APEX campaigns including nine different engine models and multiple fuel types. From the experimental data obtained in the program, the PM mass emission index (EIM) was found to range from approximately 10 to 550 mg/kg of fuel burned. The particle number emission indices (EIN) ranged from approximately 1(10)15 to 1(10)17 particles/kg of fuel burned with a logarithmic decrease of EIN with increasing fuel flow (engine power). The particle size distributions of the emissions found in the study were generally unimodal and lognormally distributed with electrical mobility diameters ranging from ~3 to slightly larger than 100 . The emission indices for black carbon (BC) and particle surface-bound PAHs (polycyclic aromatic hydrocarbons) generally follow trends similar to ElM except that: (1) BC was always highest at high power, and (2) fuel composition had no measurable effect on either BC or PAH emissions. Sulfate was by far the most abundant water-soluble ion determined in the particle-phase. Finally, over 70% of the particle-phase organic compounds determined from the quartz filters consisted of n-alkanes and PAHs.


John S. Kinsey

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