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Lintusaari H, Kuuluvainen H, Vanhanen J, Salo L, Portin H, Järvinen A, Juuti P, Hietikko R, Teinilä K, Timonen H, Niemi JV, Rönkkö T. Sub-23 nm Particles Dominate Non-Volatile Particle Number Emissions of Road Traffic. Environ Sci Technol 2023. [PMID: 37448254 PMCID: PMC10373488 DOI: 10.1021/acs.est.3c03221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
Ultrafine particles (<100 nm) in urban air are a serious health hazard not yet fully understood. Therefore, particle number concentration monitoring was recently included in the WHO air quality guidelines. At present, e.g., the EU regulates particle number only regarding the emissions of solid particles larger than 23 nm emitted by vehicles. The aim of this study was to examine the non-volatile fraction of sub-23 nm particles in a traffic-influenced urban environment. We measured the number concentration of particles larger than 1.4, 3, 10, and 23 nm in May 2018. Volatile compounds were thermally removed in the sampling line and the line losses were carefully determined. According to our results, the sub-23 nm particles dominated the non-volatile number concentrations. Additionally, based on the determined particle number emission factors, the traffic emissions of non-volatile sub-10 nm particles can be even 3 times higher than those of particles larger than 10 nm. Yet, only a fraction of urban sub-10 nm particles consisted of non-volatiles. Thus, while the results highlight the role of ultrafine particles in the traffic-influenced urban air, a careful consideration is needed in terms of future particle number standards to cover the varying factors affecting measured concentrations.
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Affiliation(s)
- Henna Lintusaari
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | - Heino Kuuluvainen
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | | | - Laura Salo
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | - Harri Portin
- Helsinki Region Environmental Services Authority, Helsinki 00240, Finland
| | - Anssi Järvinen
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | - Paxton Juuti
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | - Riina Hietikko
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
| | - Kimmo Teinilä
- Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki 00560, Finland
| | - Hilkka Timonen
- Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki 00560, Finland
| | - Jarkko V Niemi
- Helsinki Region Environmental Services Authority, Helsinki 00240, Finland
| | - Topi Rönkkö
- Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33720, Finland
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Yang S, Licina D, Weschler CJ, Wang N, Zannoni N, Li M, Vanhanen J, Langer S, Wargocki P, Williams J, Bekö G. Ozone Initiates Human-Derived Emission of Nanocluster Aerosols. Environ Sci Technol 2021; 55:14536-14545. [PMID: 34672572 DOI: 10.1021/acs.est.1c03379] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanocluster aerosols (NCAs, particles <3 nm) are important players in driving climate feedbacks and processes that impact human health. This study reports, for the first time, NCA formation when gas-phase ozone reacts with human surfaces. In an occupied climate-controlled chamber, we detected NCA only when ozone was present. NCA emissions were dependent on clothing coverage, occupant age, air temperature, and humidity. Ozone-initiated chemistry with human skin lipids (particularly their primary surface reaction products) is the key mechanism driving NCA emissions, as evidenced by positive correlations with squalene in human skin wipe samples and known gaseous products from ozonolysis of skin lipids. Oxidation by OH radicals, autoxidation reactions, and human-emitted NH3 may also play a role in NCA formation. Such chemical processes are anticipated to generate aerosols of the smallest size (1.18-1.55 nm), whereas larger clusters result from subsequent growth of the smaller aerosols. This study shows that whenever we encounter ozone indoors, where we spend most of our lives, NCAs will be produced in the air around us.
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Affiliation(s)
- Shen Yang
- Human-Oriented Built Environment Lab, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Dusan Licina
- Human-Oriented Built Environment Lab, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Charles J Weschler
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Nijing Wang
- Max Planck Institute for Chemistry, Hahn-Meitner Weg 1, Mainz 55128, Germany
| | - Nora Zannoni
- Max Planck Institute for Chemistry, Hahn-Meitner Weg 1, Mainz 55128, Germany
| | - Mengze Li
- Max Planck Institute for Chemistry, Hahn-Meitner Weg 1, Mainz 55128, Germany
| | - Joonas Vanhanen
- Airmodus Limited, Erik Palménin Aukio 1, Helsinki FI-00560, Finland
| | - Sarka Langer
- IVL Swedish Environmental Research Institute, Göteborg SE-400 14, Sweden
- Department of Architecture and Civil Engineering, Division of Building Services Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
| | - Pawel Wargocki
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Jonathan Williams
- Max Planck Institute for Chemistry, Hahn-Meitner Weg 1, Mainz 55128, Germany
- Energy, Environment and Water Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Gabriel Bekö
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark
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Patel S, Sankhyan S, Boedicker EK, DeCarlo PF, Farmer DK, Goldstein AH, Katz EF, Nazaroff WW, Tian Y, Vanhanen J, Vance ME. Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures. Environ Sci Technol 2020; 54:7107-7116. [PMID: 32391692 DOI: 10.1021/acs.est.0c00740] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM2.5 mass concentrations (assuming a density of 1 g cm-3) exceeded 250 μg m-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day.
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Affiliation(s)
- Sameer Patel
- Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, 427 UCB, Boulder, Colorado 80309, United States
| | - Sumit Sankhyan
- Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, 427 UCB, Boulder, Colorado 80309, United States
| | - Erin K Boedicker
- Department of Chemistry, Colorado State University, 200 West Lake Street, Fort Collins, Colorado 80523, United States
| | - Peter F DeCarlo
- Department of Civil, Architectural, and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Delphine K Farmer
- Department of Chemistry, Colorado State University, 200 West Lake Street, Fort Collins, Colorado 80523, United States
| | - Allen H Goldstein
- Department of Civil and Environmental Engineering, University of California at Berkeley, 760 Davis Hall, Berkeley, California 94720, United States
| | - Erin F Katz
- Department of Civil, Architectural, and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - William W Nazaroff
- Department of Civil and Environmental Engineering, University of California at Berkeley, 760 Davis Hall, Berkeley, California 94720, United States
| | - Yilin Tian
- Department of Civil and Environmental Engineering, University of California at Berkeley, 760 Davis Hall, Berkeley, California 94720, United States
| | - Joonas Vanhanen
- Airmodus Oy, Erik Palménin aukio 1, FI-00560 Helsinki, Finland
| | - Marina E Vance
- Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, 427 UCB, Boulder, Colorado 80309, United States
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Vanhanen J, Nuutinen S, Lintunen M, Mäki T, Rämö J, Karlstedt K, Panula P. Histamine is required for H₃ receptor-mediated alcohol reward inhibition, but not for alcohol consumption or stimulation. Br J Pharmacol 2014; 170:177-87. [PMID: 23489295 DOI: 10.1111/bph.12170] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/05/2013] [Accepted: 02/13/2013] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE Conflicting data have been published on whether histamine is inhibitory to the rewarding effects of abused drugs. The purpose of this study was to clarify the role of neuronal histamine and, in particular, H₃ receptors in alcohol dependence-related behaviours, which represent the addictive effects of alcohol. EXPERIMENTAL APPROACH Alcohol-induced conditioned place preference (alcohol-CPP) was used to measure alcohol reward. Alcohol-induced locomotor stimulation, alcohol consumption and kinetics were also assessed. mRNA levels were quantified using radioactive in situ hybridization. KEY RESULTS Low doses of H₃ receptor antagonists, JNJ-10181457 and JNJ-39220675, inhibited alcohol reward in wild-type (WT) mice. However, these H₃ receptor antagonists did not inhibit alcohol reward in histidine decarboxylase knock-out (HDC KO) mice and a lack of histamine did not alter alcohol consumption. Thus H₃ receptor antagonists inhibited alcohol reward in a histamine-dependent manner. Furthermore, WT and HDC KO mice were similarly stimulated by alcohol. The expression levels of dopamine D₁ and D₂ receptors, STEP61 and DARPP-32 mRNA in striatal subregions were unaltered in HDC KO mice. No differences were seen in alcohol kinetics in HDC KO compared to WT control animals. In addition, JNJ-39220675 had no effect on alcohol kinetics in WT mice. CONCLUSIONS AND IMPLICATIONS These data suggest that histamine is required for the H₃ receptor-mediated inhibition of alcohol-CPP and support the hypothesis that the brain histaminergic system has an inhibitory role in alcohol reward. Increasing neuronal histamine release via H₃ receptor blockade could therefore be a novel way of treating alcohol dependence.
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Affiliation(s)
- J Vanhanen
- Neuroscience Center and Institute of Biomedicine, University of Helsinki, Finland
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Vanhanen J, Wilenius J, Kirveskari E. P508: MEG aids in differentiating continuous epileptiform activity from EEG breach rhythm, a case report. Clin Neurophysiol 2014. [DOI: 10.1016/s1388-2457(14)50606-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kulmala M, Kontkanen J, Junninen H, Lehtipalo K, Manninen HE, Nieminen T, Petäjä T, Sipilä M, Schobesberger S, Rantala P, Franchin A, Jokinen T, Järvinen E, Äijälä M, Kangasluoma J, Hakala J, Aalto PP, Paasonen P, Mikkilä J, Vanhanen J, Aalto J, Hakola H, Makkonen U, Ruuskanen T, Mauldin RL, Duplissy J, Vehkamäki H, Bäck J, Kortelainen A, Riipinen I, Kurtén T, Johnston MV, Smith JN, Ehn M, Mentel TF, Lehtinen KEJ, Laaksonen A, Kerminen VM, Worsnop DR. Direct observations of atmospheric aerosol nucleation. Science 2013; 339:943-6. [PMID: 23430652 DOI: 10.1126/science.1227385] [Citation(s) in RCA: 323] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation--more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.
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Kulmala M, Kontkanen J, Junninen H, Lehtipalo K, Manninen HE, Nieminen T, Petäjä T, Sipilä M, Schobesberger S, Rantala P, Franchin A, Jokinen T, Järvinen E, Äijälä M, Kangasluoma J, Hakala J, Aalto PP, Paasonen P, Mikkilä J, Vanhanen J, Aalto J, Hakola H, Makkonen U, Ruuskanen T, Mauldin RL, Duplissy J, Vehkamäki H, Bäck J, Kortelainen A, Riipinen I, Kurtén T, Johnston MV, Smith JN, Ehn M, Mentel TF, Lehtinen KEJ, Laaksonen A, Kerminen VM, Worsnop DR. Direct observations of atmospheric aerosol nucleation. Science 2013. [PMID: 23430652 DOI: 10.1126/science.1227385.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation--more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.
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Kirkby J, Curtius J, Almeida J, Dunne E, Duplissy J, Ehrhart S, Franchin A, Gagné S, Ickes L, Kürten A, Kupc A, Metzger A, Riccobono F, Rondo L, Schobesberger S, Tsagkogeorgas G, Wimmer D, Amorim A, Bianchi F, Breitenlechner M, David A, Dommen J, Downard A, Ehn M, Flagan RC, Haider S, Hansel A, Hauser D, Jud W, Junninen H, Kreissl F, Kvashin A, Laaksonen A, Lehtipalo K, Lima J, Lovejoy ER, Makhmutov V, Mathot S, Mikkilä J, Minginette P, Mogo S, Nieminen T, Onnela A, Pereira P, Petäjä T, Schnitzhofer R, Seinfeld JH, Sipilä M, Stozhkov Y, Stratmann F, Tomé A, Vanhanen J, Viisanen Y, Vrtala A, Wagner PE, Walther H, Weingartner E, Wex H, Winkler PM, Carslaw KS, Worsnop DR, Baltensperger U, Kulmala M. Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation. Nature 2011. [PMID: 21866156 DOI: 10.1038/nature10343.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100-1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H(2)SO(4)-H(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.
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Sipila M, Berndt T, Petaja T, Brus D, Vanhanen J, Stratmann F, Patokoski J, Mauldin RL, Hyvarinen AP, Lihavainen H, Kulmala M. The Role of Sulfuric Acid in Atmospheric Nucleation. Science 2010; 327:1243-6. [DOI: 10.1126/science.1180315] [Citation(s) in RCA: 582] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Riipinen I, Koponen IK, Frank GP, Hyvärinen AP, Vanhanen J, Lihavainen H, Lehtinen KEJ, Bilde M, Kulmala M. Adipic and Malonic Acid Aqueous Solutions: Surface Tensions and Saturation Vapor Pressures. J Phys Chem A 2007; 111:12995-3002. [DOI: 10.1021/jp073731v] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ilona Riipinen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Ismo K. Koponen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Göran P. Frank
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Antti-Pekka Hyvärinen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Joonas Vanhanen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Heikki Lihavainen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Kari E. J. Lehtinen
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Merete Bilde
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Markku Kulmala
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, Finnish Meteorological Institute, Erik Palménin Aukio 1, P.O. Box 503, FI-00101 Helsinki, Finland, and Department of Applied Physics, University of Kuopio, and Finnish Meteorological Institute, P.O. Box 1627, FI-70211 Kuopio, Finland
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