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Proc Natl Acad Sci U S A

Title:		Traffic is a major source of atmospheric nanocluster aerosol
Author(s):		Ronkko T; Kuuluvainen H; Karjalainen P; Keskinen J; Hillamo R; Niemi JV; Pirjola L; Timonen HJ; Saarikoski S; Saukko E; Jarvinen A; Silvennoinen H; Rostedt A; Olin M; Yli-Ojanpera J; Nousiainen P; Kousa A; Dal Maso M;
Address:		"Aerosol Physics, Faculty of Natural Sciences, Tampere University of Technology, FI-33101 Tampere, Finland; topi.ronkko@tut.fi. Aerosol Physics, Faculty of Natural Sciences, Tampere University of Technology, FI-33101 Tampere, Finland. Atmospheric Composition Research, Finnish Meteorological Institute, FI-00101 Helsinki, Finland. Helsinki Region Environmental Services Authority, FI-00520 Helsinki, Finland. Department of Technology, Metropolia University of Applied Sciences, FI-00180 Helsinki, Finland. Faculty of Technology, Environment, and Business, Turku University of Applied Sciences, FI-20700 Turku, Finland"
Journal Title:		Proc Natl Acad Sci U S A
Year:		2017
Volume:		20170703
Issue:		29
Page Number:		7549 - 7554
DOI:		10.1073/pnas.1700830114
ISSN/ISBN:		1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking)
Abstract:		"In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4.10(15) (kg(fuel))(-1) in a roadside environment, 2.6.10(15) (kg(fuel))(-1) in a street canyon, and 2.9.10(15) (kg(fuel))(-1) in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6.10(12) (kg(fuel))(-1) to a high value of 4.3.10(15) (kg(fuel))(-1) These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds"
Keywords:		air pollution atmospheric aerosol combustion-derived nanoparticles nanocluster aerosol traffic emission;
Notes:		"PubMed-not-MEDLINERonkko, Topi Kuuluvainen, Heino Karjalainen, Panu Keskinen, Jorma Hillamo, Risto Niemi, Jarkko V Pirjola, Liisa Timonen, Hilkka J Saarikoski, Sanna Saukko, Erkka Jarvinen, Anssi Silvennoinen, Henna Rostedt, Antti Olin, Miska Yli-Ojanpera, Jaakko Nousiainen, Pekka Kousa, Anu Dal Maso, Miikka eng Research Support, Non-U.S. Gov't 2017/07/05 Proc Natl Acad Sci U S A. 2017 Jul 18; 114(29):7549-7554. doi: 10.1073/pnas.1700830114. Epub 2017 Jul 3"