Particulate emissions from in-use commercial aircraft

Particulate emission indices ( per kg fuel) have been determined by sampling the advected plumes of in-use commercial aircraft at two different airports using a novel approach. Differences are observed in the number, magnitude, and composition of the particle emissions between idle and take-off. At the first airport, Electrical Low Pressure Impactor (ELPI) data indicate that number based emission indices (EIn) vary by an order of magnitude for take-off plumes from different aircraft. Additionally, EIn values for idle plumes are greater than take-off. At the second airport, EIn values derived from condensation particle counter (CPC) measurements span similar to an order of magnitude (3.50 x 10(15) particles per kg fuel). The median values of the idle and take-off plumes were 1.8 x 10(16) and 7.6 x 10(15) particles per kg fuel, respectively. For take-off plumes, the magnitude of the particulate emission index is not correlated with NOx at either airport. The surface properties of the particulate emissions in take-off and idle plumes differ significantly as measured by diffusion charging (DC) and photoelectric aerosol sensor (PAS) instruments. Results indicate that takeoff plumes are characterized by particles with photoelectric-active surfaces, presumably elemental carbon, whereas idle plumes are composed of non-photoelectric-active constituents and coated soot particles. Measurements of the particulate size distribution (ELPI) show evidence for two modes, one at similar to 90 nm aerodynamic diameter and a second mode at or below the instrument cutoff (< 30 nm).