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 (EI _n ) vary by an order of magnitude for take-off plumes from different aircraft. Additionally, EI _n values for idle plumes are greater than take-off. At the second airport, EI _n values derived from condensation particle counter (CPC) measurements span ∼ an order of magnitude (3–50 × 10 ¹⁵ particles per kg fuel). The median values of the idle and take-off plumes were 1.8 × 10 ¹⁶ and 7.6 × 10 ¹⁵ particles per kg fuel, respectively. For take-off plumes, the magnitude of the particulate emission index is not correlated with NO _x 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 take-off 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 ∼ 90 nm aerodynamic diameter and a second mode at or below the instrument cutoff ( < 30 nm).

Acknowledgments

These measurements would not have been possible without cooperation from The Port Authority of NY & NJ, specifically LaGuardia and John F. Kennedy International Airport Operations Staff, “99,” “97,” and “93.” The authors gratefully acknowledge the assistance of Flavio Leo, Aviation Planning Manager and Vincent Cardillo, Airport Operations Manager at The Massachusetts Port Authority. We would like to thank Gregg Fleming of Volpe National Transportation Systems Center for helping set up the Logan measurements and providing assistance in the analysis of the JFK results. We would also like to thank Shida Tang of the New York State Department of Environmental Conservation for assistance in the analysis of the ELPI data and helpful discussions. This work was funded in part by the EPA Supersite Programs: PMTACS-NY and CEPEX, the MCMA field measurement program within the Integrated Program on Urban, Regional, and Global Air Pollution at Mass. Institute of Technology and the NOAA Global Climate Change program.

Notes

^a EI NOx is expressed as g NO₂ per kg fuel.

^b EIn measured by two instruments with different sample size ranges: ELPI at JFK (30–2500 nm) and CPC at Logan (7–2500 nm).

^c Units for DC and PAS instruments are provided using factory calibration.

^d Fishers skewness coefficient.