Prof. Dr. Urs Baltensperger

Urs Baltensperger
Urs Baltensperger

Laboratory Head

Paul Scherrer Institute
Forschungsstrasse 111
5232 Villigen PSI
Switzerland
Telefon
+41 56 310 24 08




Clarivate Analytics (formerly Thomson Reuters) Highly Cited Researcher

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2014

2015

2016

2017
2018

2019

 2020

Year Award
2016
Royal Society of Chemistry Spiers Memorial Award 2016
Urs Baltensperger

Awarded for leading major advances in understanding the formation, composition and processes affecting atmospheric organic aerosols
Chemistry in the Urban Atmosphere: Faraday Discussion, 6 - 8 April 2016, London, UK.
2014
Fuchs Memorial Award 2014, IARA - International Aerosol Research Assembly
Urs Baltensperger

"In recognition of outstanding original research contributions to aerosol science and technology"
9th International Aerosol Conference, Busan, Korea
2014
Vilhelm Bjerknes Medal, European Geosciences Union
Urs Baltensperger
2012
Fellow of the American Geophysical Union

Urs Baltensperger
2006
PSI-Preis für Wissenschaftskommunikation 2006
(PSI Award for Science Communication 2006)
André Prévôt, Urs Baltensperger

Neueste Erkenntnisse über die Quellen von Feinstaub in der Schweiz (Latest insight into the sources of fine particulate matter in Switzerland)
2003
PSI Preis für Wissenschaftskommunikation 2003 (PSI Award for Science Communication 2003)
Ernest Weingartner, Pascale Weingartner, Severin Weber, Markus Furger, Urs Baltensperger

Website on Aerosol Research at PSI, PSI News (in German)
2003
18th Professor Dr. Vilho Vaisala Award (2003)
Ernest Weingartner, Martin Gysel, Urs Baltensperger

World Meteorological Organization (WMO), Geneva, Switzerland
Committee / Function Period
Schweizerische Kommission für die hochalpine Forschungsstation Jungfraujoch, Präsident
(Swiss Commission for the high-alpine Research Station Jungfraujoch, President)		 2019 - 
Nationaler Forschungsrat des SNF, Präsident des Fachausschusses Internationale Zusammenarbeit
(National Research Council of the Swiss National Science Foundation SNSF, President of the Specialised Committee International Co-operation)		 1 Oct 2013 -
Nationaler Forschungsrat des SNF, Bereich Umweltwissenschaften
(National Research Council of the Swiss National Science Foundation SNSF, Division Environmental Sciences)		 2010 -
SCNAT Commission on Atmospheric Chemistry and Physics
President until 2010, member since 2011		 2002 -
Atmospheric Chemistry and Physics
Co-editor		 2003 -
Scientific Advisory Group for Aerosols of the Global Atmosphere Watch Programme of WMO
Chairman / Member since 2011		 1997 -
Gesellschaft für Aerosolforschung
Secretary General		 1998 - 2002
Umweltbeirat at the Research Centre Jülich
Chairman		 2004 - 2011
  • Amaladhasan DA, Heyn C, Hoyle CR, El Haddad I, Elser M, Pieber SM, et al.
    Modelling the gas-particle partitioning and water uptake of isoprene-derived secondary organic aerosol at high and low relative humidity
    Atmospheric Chemistry and Physics. 2022; 22(1): 215-244. https://doi.org/10.5194/acp-22-215-2022
    DORA PSI
  • Casotto R, Cvitešić Kušan A, Bhattu D, Cui T, Manousakas MI, Frka S, et al.
    Chemical composition and sources of organic aerosol on the Adriatic coast in Croatia
    Atmospheric Environment: X. 2022; 13: 100159 (14 pp.). https://doi.org/10.1016/j.aeaoa.2022.100159
    DORA PSI
  • Chen G, Canonaco F, Tobler A, Aas W, Alastuey A, Allan J, et al.
    European aerosol phenomenology − 8: Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets
    Environment International. 2022; 166: 107325. https://doi.org/10.1016/j.envint.2022.107325
    DORA PSI
  • Marten R, Xiao M, Rörup B, Wang M, Kong W, He X-C, et al.
    Survival of newly formed particles in haze conditions
    Environmental Science: Atmospheres. 2022; 2(3): 491-499. https://doi.org/10.1039/d2ea00007e
    DORA PSI
  • Moschos V, Schmale J, Aas W, Becagli S, Calzolai G, Eleftheriadis K, et al.
    Elucidating the present-day chemical composition, seasonality and source regions of climate-relevant aerosols across the Arctic land surface
    Environmental Research Letters. 2022; 17(3): 034032 (14 pp.). https://doi.org/10.1088/1748-9326/ac444b
    DORA PSI
  • Moschos V, Dzepina K, Bhattu D, Lamkaddam H, Casotto R, Daellenbach KR, et al.
    Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols
    Nature Geoscience. 2022; 15: 196-202. https://doi.org/10.1038/s41561-021-00891-1
    DORA PSI
  • Qi L, Bozzetti C, Corbin JC, Daellenbach KR, El Haddad I, Zhang Q, et al.
    Source identification and characterization of organic nitrogen in atmospheric aerosols at a suburban site in China
    Science of the Total Environment. 2022; 818: 151800 (11 pp.). https://doi.org/10.1016/j.scitotenv.2021.151800
    DORA PSI
  • Baccarini A, Dommen J, Lehtipalo K, Henning S, Modini RL, Gysel‐Beer M, et al.
    Low‐volatility vapors and new particle formation over the Southern Ocean during the Antarctic Circumnavigation Expedition
    Journal of Geophysical Research D: Atmospheres. 2021; 126(22): e2021JD035126 (25 pp.). https://doi.org/10.1029/2021JD035126
    DORA PSI
  • Bianchi F, Junninen H, Bigi A, Sinclair VA, Dada L, Hoyle CR, et al.
    Biogenic particles formed in the Himalaya as an important source of free tropospheric aerosols
    Nature Geoscience. 2021; 14: 4-9. https://doi.org/10.1038/s41561-020-00661-5
    DORA PSI
  • Bukowiecki N, Brem BT, Wehrle G, Močnik G, Affolter S, Leuenberger M, et al.
    Elucidating local pollution and site representativeness at the Jungfraujoch, Switzerland through parallel aerosol measurements at an adjacent mountain ridge
    Environmental Research Communications. 2021; 3(2): 021001 (12 pp.). https://doi.org/10.1088/2515-7620/abe987
    DORA PSI
  • Canonaco F, Tobler A, Chen G, Sosedova Y, Slowik JG, Bozzetti C, et al.
    A new method for long-term source apportionment with time-dependent factor profiles and uncertainty assessment using SoFi Pro: application to 1 year of organic aerosol data
    Atmospheric Measurement Techniques. 2021; 14(2): 923-943. https://doi.org/10.5194/amt-14-923-2021
    DORA PSI
  • Cassagnes LE, Leni Z, Håland A, Bell DM, Zhu L, Bertrand A, et al.
    Online monitoring of volatile organic compounds emitted from human bronchial epithelial cells as markers for oxidative stress
    Journal of Breath Research. 2021; 15(1): 016015 (11 pp.). https://doi.org/10.1088/1752-7163/abc055
    DORA PSI
  • Caudillo L, Rörup B, Heinritzi M, Marie G, Simon M, Wagner AC, et al.
    Chemical composition of nanoparticles from α-pinene nucleation and the influence of isoprene and relative humidity at low temperature
    Atmospheric Chemistry and Physics. 2021; 21(22): 17099-17114. https://doi.org/10.5194/acp-21-17099-2021
    DORA PSI
  • Chen G, Sosedova Y, Canonaco F, Fröhlich R, Tobler A, Vlachou A, et al.
    Time-dependent source apportionment of submicron organic aerosol for a rural site in an alpine valley using a rolling positive matrix factorisation (PMF) window
    Atmospheric Chemistry and Physics. 2021; 21(19): 15081-15101. https://doi.org/10.5194/acp-21-15081-2021
    DORA PSI
  • Eugster W, Baumgartner LP, Bachmann O, Baltensperger U, Dèzes P, Dubois N, et al.
    Geosciences roadmap for research infrastructures 2025–2028 by the Swiss Geosciences Community
    Bern: Swiss Academy of Sciences (SCNAT); 2021. Swiss Academies reports: 16/4. https://doi.org/10.5281/zenodo.4588881
    DORA PSI
  • Giannoukos S, Tarik M, Ludwig C, Biollaz S, Slowik J, Baltensperger U, et al.
    Detection of trace metals in biogas using extractive electrospray ionization high-resolution mass spectrometry
    Renewable Energy. 2021; 169: 780-787. https://doi.org/10.1016/j.renene.2021.01.047
    DORA PSI
  • He X-C, Iyer S, Sipilä M, Ylisirniö A, Peltola M, Kontkanen J, et al.
    Determination of the collision rate coefficient between charged iodic acid clusters and iodic acid using the appearance time method
    Aerosol Science and Technology. 2021; 55(2): 231-242. https://doi.org/10.1080/02786826.2020.1839013
    DORA PSI
  • He X-C, Tham YJ, Dada L, Wang M, Finkenzeller H, Stolzenburg D, et al.
    Role of iodine oxoacids in atmospheric aerosol nucleation
    Science. 2021; 371(6529): 589-595. https://doi.org/10.1126/science.abe0298
    DORA PSI
  • Jiang J, El Haddad I, Aksoyoglu S, Stefenelli G, Bertrand A, Marchand N, et al.
    Influence of biomass burning vapor wall loss correction on modeling organic aerosols in Europe by CAMx v6.50
    Geoscientific Model Development. 2021; 14(3): 1681-1697. https://doi.org/10.5194/gmd-14-1681-2021
    DORA PSI
  • Lamkaddam H, Dommen J, Ranjithkumar A, Gordon H, Wehrle G, Krechmer J, et al.
    Large contribution to secondary organic aerosol from isoprene cloud chemistry
    Science Advances. 2021; 7(13): eabe2952 (10 pp.). https://doi.org/10.1126/sciadv.abe2952
    DORA PSI
  • Lee CP, Surdu M, Bell DM, Lamkaddam H, Wang M, Ataei F, et al.
    Effects of aerosol size and coating thickness on the molecular detection using extractive electrospray ionization
    Atmospheric Measurement Techniques. 2021; 14(9): 5913-5923. https://doi.org/10.5194/amt-14-5913-2021
    DORA PSI
  • Moschos V, Gysel-Beer M, Modini RL, Corbin JC, Massabò D, Costa C, et al.
    Source-specific light absorption by carbonaceous components in the complex aerosol matrix from yearly filter-based measurements
    Atmospheric Chemistry and Physics. 2021; 21(17): 12809-12833. https://doi.org/10.5194/acp-21-12809-2021
    DORA PSI
  • Ni H, Huang R-J, Pieber SM, Corbin JC, Stefenelli G, Pospisilova V, et al.
    Brown carbon in primary and aged coal combustion emission
    Environmental Science and Technology. 2021; 55(9): 5701-5710. https://doi.org/10.1021/acs.est.0c08084
    DORA PSI
  • Pileci RE, Modini RL, Bertò M, Yuan J, Corbin JC, Marinoni A, et al.
    Comparison of co-located refractory black carbon (rBC) and elemental carbon (EC) mass concentration measurements during field campaigns at several European sites
    Atmospheric Measurement Techniques. 2021; 14(2): 1379-1403. https://doi.org/10.5194/amt-14-1379-2021
    DORA PSI
  • Pospisilova V, Bell DM, Lamkaddam H, Bertrand A, Wang L, Bhattu D, et al.
    Photodegradation of α-pinene secondary organic aerosol dominated by moderately oxidized molecules
    Environmental Science and Technology. 2021; 55(10): 6936-6943. https://doi.org/10.1021/acs.est.0c06752
    DORA PSI
  • Rai P, Furger M, Slowik JG, Zhong H, Tong Y, Wang L, et al.
    Characteristics and sources of hourly elements in PM10 and PM2.5 during wintertime in Beijing
    Environmental Pollution. 2021; 278: 116865 (11 pp.). https://doi.org/10.1016/j.envpol.2021.116865
    DORA PSI
  • Rai P, Slowik JG, Furger M, El Haddad I, Visser S, Tong Y, et al.
    Highly time-resolved measurements of element concentrations in PM10 and PM2.5: comparison of Delhi, Beijing, London, and Krakow
    Atmospheric Chemistry and Physics. 2021; 21(2): 717-730. https://doi.org/10.5194/acp-21-717-2021
    DORA PSI
  • Rose C, Collaud Coen M, Andrews E, Lin Y, Bossert I, Lund Myhre C, et al.
    Seasonality of the particle number concentration and size distribution: a global analysis retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
    Atmospheric Chemistry and Physics. 2021; 21(22): 17185-17223. https://doi.org/10.5194/acp-21-17185-2021
    DORA PSI
  • Surdu M, Pospisilova V, Xiao M, Wang M, Mentler B, Simon M, et al.
    Molecular characterization of ultrafine particles using extractive electrospray time-of-flight mass spectrometry
    Environmental Science: Atmospheres. 2021; 1(6): 434-448. https://doi.org/10.1039/D1EA00050K
    DORA PSI
  • Titos G, Burgos MA, Zieger P, Alados-Arboledas L, Baltensperger U, Jefferson A, et al.
    A global study of hygroscopicity-driven light-scattering enhancement in the context of other in situ aerosol optical properties
    Atmospheric Chemistry and Physics. 2021; 21(17): 13031-13050. https://doi.org/10.5194/acp-21-13031-2021
    DORA PSI
  • Tobler AK, Skiba A, Canonaco F, Močnik G, Rai P, Chen G, et al.
    Characterization of non-refractory (NR) PM1 and source apportionment of organic aerosol in Kraków, Poland
    Atmospheric Chemistry and Physics. 2021; 21(19): 14893-14906. https://doi.org/10.5194/acp-21-14893-2021
    DORA PSI
  • Tomaz S, Wang D, Zabalegui N, Li D, Lamkaddam H, Bachmeier F, et al.
    Structures and reactivity of peroxy radicals and dimeric products revealed by online tandem mass spectrometry
    Nature Communications. 2021; 12: 300 (9 pp.). https://doi.org/10.1038/s41467-020-20532-2
    DORA PSI
  • Tong Y, Pospisilova V, Qi L, Duan J, Gu Y, Kumar V, et al.
    Quantification of solid fuel combustion and aqueous chemistry contributions to secondary organic aerosol during wintertime haze events in Beijing
    Atmospheric Chemistry and Physics. 2021; 21(12): 9859-9886. https://doi.org/10.5194/acp-21-9859-2021
    DORA PSI
  • Wang L, Slowik JG, Tong Y, Duan J, Gu Y, Rai P, et al.
    Characteristics of wintertime VOCs in urban Beijing: composition and source apportionment
    Atmospheric Environment: X. 2021; 9: 100100 (12 pp.). https://doi.org/10.1016/j.aeaoa.2020.100100
    DORA PSI
  • Wang DS, Lee CP, Krechmer JE, Majluf F, Tong Y, Canagaratna MR, et al.
    Constraining the response factors of an extractive electrospray ionization mass spectrometer for near-molecular aerosol speciation
    Atmospheric Measurement Techniques. 2021; 14(11): 6955-6972. https://doi.org/10.5194/amt-14-6955-2021
    DORA PSI
  • Wu C, Bell DM, Graham EL, Haslett S, Riipinen I, Baltensperger U, et al.
    Photolytically induced changes in composition and volatility of biogenic secondary organic aerosol from nitrate radical oxidation during night-to-day transition
    Atmospheric Chemistry and Physics. 2021; 21(19): 14907-14925. https://doi.org/10.5194/acp-21-14907-2021
    DORA PSI
  • Xiao M, Hoyle CR, Dada L, Stolzenburg D, Kürten A, Wang M, et al.
    The driving factors of new particle formation and growth in the polluted boundary layer
    Atmospheric Chemistry and Physics. 2021; 21(18): 14275-14291. https://doi.org/10.5194/acp-21-14275-2021
    DORA PSI
  • Yuan J, Modini RL, Zanatta M, Herber AB, Müller T, Wehner B, et al.
    Variability in the mass absorption cross section of black carbon (BC) aerosols is driven by BC internal mixing state at a central European background site (Melpitz, Germany) in winter
    Atmospheric Chemistry and Physics. 2021; 21(2): 635-655. https://doi.org/10.5194/acp-21-635-2021
    DORA PSI
  • Aksoyoglu S, Jiang J, Ciarelli G, Baltensperger U, Prévôt ASH
    Role of ammonia in European air quality with changing land and ship emissions between 1990 and 2030
    Atmospheric Chemistry and Physics. 2020; 20(24): 15665-15680. https://doi.org/10.5194/acp-20-15665-2020
    DORA PSI
  • Baccarini A, Karlsson L, Dommen J, Duplessis P, Vüllers J, Brooks IM, et al.
    Frequent new particle formation over the high Arctic pack ice by enhanced iodine emissions
    Nature Communications. 2020; 11(1): 4924 (11 pp.). https://doi.org/10.1038/s41467-020-18551-0
    DORA PSI
  • Burgos MA, Andrews E, Titos G, Benedetti A, Bian H, Buchard V, et al.
    A global model-measurement evaluation of particle light scattering coefficients at elevated relative humidity
    Atmospheric Chemistry and Physics. 2020; 20(17): 10231-10258. https://doi.org/10.5194/acp-20-10231-2020
    DORA PSI
  • Castro A, Götschi T, Achermann B, Baltensperger U, Buchmann B, Felber Dietrich D, et al.
    Comparing the lung cancer burden of ambient particulate matter using scenarios of air quality standards versus acceptable risk levels
    International Journal of Public Health. 2020; 65: 139-148. https://doi.org/10.1007/s00038-019-01324-y
    DORA PSI
  • Daellenbach KR, Uzu G, Jiang J, Cassagnes LE, Leni Z, Vlachou A, et al.
    Sources of particulate-matter air pollution and its oxidative potential in Europe
    Nature. 2020; 587(7834): 414-419. https://doi.org/10.1038/s41586-020-2902-8
    DORA PSI
  • Esmaeilirad S, Lai A, Abbaszade G, Schnelle-Kreis J, Zimmermann R, Uzu G, et al.
    Source apportionment of fine particulate matter in a Middle Eastern Metropolis, Tehran-Iran, using PMF with organic and inorganic markers
    Science of the Total Environment. 2020; 705: 135330 (16 pp.). https://doi.org/10.1016/j.scitotenv.2019.135330
    DORA PSI
  • Furger M, Rai P, Slowik JG, Cao J, Visser S, Baltensperger U, et al.
    Automated alternating sampling of PM10 and PM2.5 with an online XRF spectrometer
    Atmospheric Environment: X. 2020; 5: 100065 (6 pp.). https://doi.org/10.1016/j.aeaoa.2020.100065
    DORA PSI
  • Giannoukos S, Lee CP, Tarik M, Ludwig C, Biollaz S, Lamkaddam H, et al.
    Real-time detection of aerosol metals using online extractive electrospray ionization mass spectrometry
    Analytical Chemistry. 2020; 92(1): 1316-1325. https://doi.org/10.1021/acs.analchem.9b04480
    DORA PSI
  • Heinritzi M, Dada L, Simon M, Stolzenburg D, Wagner AC, Fischer L, et al.
    Molecular understanding of the suppression of new-particle formation by isoprene
    Atmospheric Chemistry and Physics. 2020; 20(20): 11809-11821. https://doi.org/10.5194/acp-20-11809-2020
    DORA PSI
  • Jiang J, Aksoyoglu S, Ciarelli G, Baltensperger U, Prévôt ASH
    Changes in ozone and PM2.5 in Europe during the period of 1990–2030: role of reductions in land and ship emissions
    Science of the Total Environment. 2020; 741: 140467 (14 pp.). https://doi.org/10.1016/j.scitotenv.2020.140467
    DORA PSI
  • Laj P, Bigi A, Rose C, Andrews E, Lund Myhre C, Collaud Coen M, et al.
    A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
    Atmospheric Measurement Techniques. 2020; 13(8): 4353-4392. https://doi.org/10.5194/amt-13-4353-2020
    DORA PSI
  • Lee CP, Riva M, Wang D, Tomaz S, Li D, Perrier S, et al.
    Online aerosol chemical characterization by extractive electrospray ionization-ultrahigh-resolution mass spectrometry (EESI-Orbitrap)
    Environmental Science and Technology. 2020; 54(7): 3871-3880. https://doi.org/10.1021/acs.est.9b07090
    DORA PSI
  • Leni Z, Cassagnes LE, Daellenbach KR, El Haddad I, Vlachou A, Uzu G, et al.
    Oxidative stress-induced inflammation in susceptible airways by anthropogenic aerosol
    PLoS One. 2020; 15(11): e0233425 (17 pp.). https://doi.org/10.1371/journal.pone.0233425
    DORA PSI
  • Motos G, Corbin JC, Schmale J, Modini RL, Bertò M, Kupiszewski P, et al.
    Black carbon aerosols in the lower free troposphere are heavily coated in summer but largely uncoated in winter at Jungfraujoch in the Swiss Alps
    Geophysical Research Letters. 2020; 47(14): e2020GL088011 (10 pp.). https://doi.org/10.1029/2020GL088011
    DORA PSI
  • Petäjä T, Duplissy E-M, Tabakova K, Schmale J, Altstädter B, Ancellet G, et al.
    Overview: integrative and comprehensive understanding on polar environments (iCUPE) - concept and initial results
    Atmospheric Chemistry and Physics. 2020; 20(14): 8551-8592. https://doi.org/10.5194/acp-20-8551-2020
    DORA PSI
  • Pospisilova V, Lopez-Hilfiker FD, Bell DM, El Haddad I, Mohr C, Huang W, et al.
    On the fate of oxygenated organic molecules in atmospheric aerosol particles
    Science Advances. 2020; 6(11): eaax8922 (11 pp.). https://doi.org/10.1126/sciadv.aax8922
    DORA PSI
  • Qi L, Vogel AL, Esmaeilirad S, Cao L, Zheng J, Jaffrezo J-L, et al.
    A 1-year characterization of organic aerosol composition and sources using an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF)
    Atmospheric Chemistry and Physics. 2020; 20(13): 7875-7893. https://doi.org/10.5194/acp-20-7875-2020
    DORA PSI
  • Rai P, Furger M, El Haddad I, Kumar V, Wang L, Singh A, et al.
    Real-time measurement and source apportionment of elements in Delhi's atmosphere
    Science of the Total Environment. 2020; 742: 140332 (16 pp.). https://doi.org/10.1016/j.scitotenv.2020.140332
    DORA PSI
  • Rai P, Furger M, Slowik JG, Canonaco F, Fröhlich R, Hüglin C, et al.
    Source apportionment of highly time-resolved elements during a firework episode from a rural freeway site in Switzerland
    Atmospheric Chemistry and Physics. 2020; 20(3): 1657-1674. https://doi.org/10.5194/acp-20-1657-2020
    DORA PSI
  • Simon M, Dada L, Heinritzi M, Scholz W, Stolzenburg D, Fischer L, et al.
    Molecular understanding of new-particle formation from α-pinene between -50 and +25 °C
    Atmospheric Chemistry and Physics. 2020; 20(15): 9183-9207. https://doi.org/10.5194/acp-20-9183-2020
    DORA PSI
  • Stolzenburg D, Simon M, Ranjithkumar A, Kürten A, Lehtipalo K, Gordon H, et al.
    Enhanced growth rate of atmospheric particles from sulfuric acid
    Atmospheric Chemistry and Physics. 2020; 20(12): 7359-7372. https://doi.org/10.5194/acp-20-7359-2020
    DORA PSI
  • Tobler A, Bhattu D, Canonaco F, Lalchandani V, Shukla A, Thamban NM, et al.
    Chemical characterization of PM2.5 and source apportionment of organic aerosol in New Delhi, India
    Science of the Total Environment. 2020; 745: 140924 (12 pp.). https://doi.org/10.1016/j.scitotenv.2020.140924
    DORA PSI
  • Tobler AK, Skiba A, Wang DS, Croteau P, Styszko K, Nęcki J, et al.
    Improved chloride quantification in quadrupole aerosol chemical speciation monitors (Q-ACSMs)
    Atmospheric Measurement Techniques. 2020; 13(10): 5293-5301. https://doi.org/10.5194/amt-13-5293-2020
    DORA PSI
  • Wang M, Chen D, Xiao M, Ye Q, Stolzenburg D, Hofbauer V, et al.
    Photo-oxidation of aromatic hydrocarbons produces low-volatility organic compounds
    Environmental Science and Technology. 2020; 54(13): 7911-7921. https://doi.org/10.1021/acs.est.0c02100
    DORA PSI
  • Wang M, Kong W, Marten R, He X-C, Chen D, Pfeifer J, et al.
    Rapid growth of new atmospheric particles by nitric acid and ammonia condensation
    Nature. 2020; 581(7807): 184-189. https://doi.org/10.1038/s41586-020-2270-4
    DORA PSI
  • Wang L, Slowik JG, Tripathi N, Bhattu D, Rai P, Kumar V, et al.
    Source characterization of volatile organic compounds measured by proton-transfer-reaction time-of-flight mass spectrometers in Delhi, India
    Atmospheric Chemistry and Physics. 2020; 20(16): 9753-9770. https://doi.org/10.5194/acp-20-9753-2020
    DORA PSI
  • Yan C, Nie W, Vogel AL, Dada L, Lehtipalo K, Stolzenburg D, et al.
    Size-dependent influence of NOx on the growth rates of organic aerosol particles
    Science Advances. 2020; 6(22): eaay4945 (9 pp.). https://doi.org/10.1126/sciadv.aay4945
    DORA PSI
  • Bhattu D, Zotter P, Zhou J, Stefenelli G, Klein F, Bertrand A, et al.
    Effect of stove technology and combustion conditions on gas and particulate emissions from residential biomass combustion
    Environmental Science and Technology. 2019; 53(4): 2209-2219. https://doi.org/10.1021/acs.est.8b05020
    DORA PSI
  • Bukowiecki N, Steinbacher M, Henne S, Nguyen NA, Nguyen XA, Hoang AL, et al.
    Effect of large-scale biomass burning on aerosol optical properties at the GAW regional station Pha Din, Vietnam
    Aerosol and Air Quality Research. 2019; 19(5): 1172-1187. https://doi.org/10.4209/aaqr.2018.11.0406
    DORA PSI
  • Burgos MA, Andrews E, Titos G, Alados-Arboledas L, Baltensperger U, Day D, et al.
    A global view on the effect of water uptake on aerosol particle light scattering
    Scientific Data. 2019; 6: 157 (19 pp.). https://doi.org/10.1038/s41597-019-0158-7
    DORA PSI
  • Daellenbach KR, Kourtchev I, Vogel AL, Bruns EA, Jiang J, Petäjä T, et al.
    Impact of anthropogenic and biogenic sources on the seasonal variation in the molecular composition of urban organic aerosols: a field and laboratory study using ultra-high-resolution mass spectrometry
    Atmospheric Chemistry and Physics. 2019; 19(9): 5973-5991. https://doi.org/10.5194/acp-19-5973-2019
    DORA PSI
  • Jiang J, Aksoyoglu S, Ciarelli G, Oikonomakis E, El-Haddad I, Canonaco F, et al.
    Effects of two different biogenic emission models on modelled ozone and aerosol concentrations in Europe
    Atmospheric Chemistry and Physics. 2019; 19(6): 3747-3768. https://doi.org/10.5194/acp-19-3747-2019
    DORA PSI
  • Jiang J, Aksoyoglu S, El-Haddad I, Ciarelli G, Denier van der Gon HAC, Canonaco F, et al.
    Sources of organic aerosols in Europe: a modeling study using CAMx with modified volatility basis set scheme
    Atmospheric Chemistry and Physics. 2019; 19(24): 15247-15270. https://doi.org/10.5194/acp-19-15247-2019
    DORA PSI
  • Klein F, Baltensperger U, Prévôt ASH, El Haddad I
    Quantification of the impact of cooking processes on indoor concentrations of volatile organic species and primary and secondary organic aerosols
    Indoor Air. 2019; 29(6): 926-942. https://doi.org/10.1111/ina.12597
    DORA PSI
  • Lopez-Hilfiker FD, Pospisilova V, Huang W, Kalberer M, Mohr C, Stefenelli G, et al.
    An extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) for online measurement of atmospheric aerosol particles
    Atmospheric Measurement Techniques. 2019; 12(9): 4867-4886. https://doi.org/10.5194/amt-12-4867-2019
    DORA PSI
  • Molteni U, Simon M, Heinritzi M, Hoyle CR, Bernhammer A-K, Bianchi F, et al.
    Formation of highly oxygenated organic molecules from α-pinene ozonolysis: chemical characteristics, mechanism, and kinetic model development
    ACS Earth and Space Chemistry. 2019; 3(5): 873-883. https://doi.org/10.1021/acsearthspacechem.9b00035
    DORA PSI
  • Motos G, Schmale J, Corbin JC, Modini RL, Karlen N, Bertò M, et al.
    Cloud droplet activation properties and scavenged fraction of black carbon in liquid-phase clouds at the high-alpine research station Jungfraujoch (3580 m a.s.l.)
    Atmospheric Chemistry and Physics. 2019; 19(6): 3833-3855. https://doi.org/10.5194/acp-19-3833-2019
    DORA PSI
  • Motos G, Schmale J, Corbin JC, Zanatta M, Baltensperger U, Gysel-Beer M
    Droplet activation behaviour of atmospheric black carbon particles in fog as a function of their size and mixing state
    Atmospheric Chemistry and Physics. 2019; 19(4): 2183-2207. https://doi.org/10.5194/acp-19-2183-2019
    DORA PSI
  • Qi L, Chen M, Stefenelli G, Pospisilova V, Tong Y, Bertrand A, et al.
    Organic aerosol source apportionment in Zurich using an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS) – part 2: biomass burning influences in winter
    Atmospheric Chemistry and Physics. 2019; 19(12): 8037-8062. https://doi.org/10.5194/acp-19-8037-2019
    DORA PSI
  • Schmale J, Baccarini A, Thurnherr I, Henning S, Efraim A, Regayre L, et al.
    Overview of the Antarctic Circumnavigation Expedition: study of preindustrial-like aerosols and their climate effects (ACE-SPACE)
    Bulletin of the American Meteorological Society. 2019; 100: 2260-2283. https://doi.org/10.1175/BAMS-D-18-0187.1
    DORA PSI
  • Sorensen CM, Flagan RC, Baltensperger U, Pui DYH
    Grand challenges for aerosol science and technology
    Aerosol Science and Technology. 2019; 53(7): 731-734. https://doi.org/10.1080/02786826.2019.1611333
    DORA PSI
  • Stefenelli G, Pospisilova V, Lopez-Hilfiker FD, Daellenbach KR, Hüglin C, Tong Y, et al.
    Organic aerosol source apportionment in Zurich using an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS) - part 1: biogenic influences and day-night chemistry in summer
    Atmospheric Chemistry and Physics. 2019; 19(23): 14825-14848. https://doi.org/10.5194/acp-19-14825-2019
    DORA PSI
  • Stefenelli G, Jiang J, Bertrand A, Bruns EA, Pieber SM, Baltensperger U, et al.
    Secondary organic aerosol formation from smoldering and flaming combustion of biomass: a box model parametrization based on volatility basis set
    Atmospheric Chemistry and Physics. 2019; 19(17): 11461-11484. https://doi.org/10.5194/acp-19-11461-2019
    DORA PSI
  • Vlachou A, Tobler A, Lamkaddam H, Canonaco F, Daellenbach KR, Jaffrezo J-L, et al.
    Development of a versatile source apportionment analysis based on positive matrix factorization: a case study of the seasonal variation of organic aerosol sources in Estonia
    Atmospheric Chemistry and Physics. 2019; 19(11): 7279-7295. https://doi.org/10.5194/acp-19-7279-2019
    DORA PSI
  • Vogel AL, Lauer A, Fang L, Arturi K, Bachmeier F, Daellenbach KR, et al.
    A comprehensive nontarget analysis for the molecular reconstruction of organic aerosol composition from glacier ice cores
    Environmental Science and Technology. 2019; 53(21): 12565-12575. https://doi.org/10.1021/acs.est.9b03091
    DORA PSI
  • Ye Q, Wang M, Hofbauer V, Stolzenburg D, Chen D, Schervish M, et al.
    Molecular composition and volatility of nucleated particles from α-pinene oxidation between -50 °C and +25 °C
    Environmental Science and Technology. 2019; 53(21): 12357-12365. https://doi.org/10.1021/acs.est.9b03265
    DORA PSI
  • Zhou J, Elser M, Huang R-J, Krapf M, Fröhlich R, Bhattu D, et al.
    Predominance of secondary organic aerosol to particle-bound reactive oxygen species activity in fine ambient aerosol
    Atmospheric Chemistry and Physics. 2019; 19(23): 14703-14720. https://doi.org/10.5194/acp-19-14703-2019
    DORA PSI
  • Aksoyoglu S, Ciarelli G, El Haddad I, Baltensperger U, Prevot ASH
    Source apportionment of inorganic aerosols in Europe and role of biogenic VOC emissions
    In: Mensink C, Kallos G, eds. Air pollution modelling and its application XXV. Springer proceedings in complexity. Cham: Springer; 2018:375-379. https://doi.org/10.1007/978-3-319-57645-9_59
    DORA PSI
  • Bertrand A, Stefenelli G, Jen CN, Pieber SM, Bruns EA, Ni H, et al.
    Evolution of the chemical fingerprint of biomass burning organic aerosol during aging
    Atmospheric Chemistry and Physics. 2018; 18(10): 7607-7624. https://doi.org/10.5194/acp-18-7607-2018
    DORA PSI
  • Daellenbach KR, El-Haddad I, Karvonen L, Vlachou A, Corbin JC, Slowik JG, et al.
    Insights into organic-Aerosol sources via a novel laser-desorption/ionization mass spectrometry technique applied to one year of PM10 samples from nine sites in central Europe
    Atmospheric Chemistry and Physics. 2018; 18(3): 2155-2174. https://doi.org/10.5194/acp-18-2155-2018
    DORA PSI
  • Elser M, El-Haddad I, Maasikmets M, Bozzetti C, Wolf R, Ciarelli G, et al.
    High contributions of vehicular emissions to ammonia in three European cities derived from mobile measurements
    Atmospheric Environment. 2018; 175: 210-220. https://doi.org/10.1016/j.atmosenv.2017.11.030
    DORA PSI
  • Frege C, Ortega IK, Rissanen MP, Praplan AP, Steiner G, Heinritzi M, et al.
    Influence of temperature on the molecular composition of ions and charged clusters during pure biogenic nucleation
    Atmospheric Chemistry and Physics. 2018; 18(1): 65-79. https://doi.org/10.5194/acp-18-65-2018
    DORA PSI
  • Kiliç D, El Haddad I, Brem BT, Bruns E, Bozetti C, Corbin J, et al.
    Identification of secondary aerosol precursors emitted by an aircraft turbofan
    Atmospheric Chemistry and Physics. 2018; 18(10): 7379-7391. https://doi.org/10.5194/acp-18-7379-2018
    DORA PSI
  • Klein F, Pieber SM, Ni H, Stefenelli G, Bertrand A, Kilic D, et al.
    Characterization of gas-phase organics using proton transfer reaction time-of-flight mass spectrometry: residential coal combustion
    Environmental Science and Technology. 2018; 52(5): 2612-2617. https://doi.org/10.1021/acs.est.7b03960
    DORA PSI
  • Kumar NK, Corbin JC, Bruns EA, Massabó D, Slowik JG, Drinovec L, et al.
    Production of particulate brown carbon during atmospheric aging of residential wood-burning emissions
    Atmospheric Chemistry and Physics. 2018; 18(24): 17843-17861. https://doi.org/10.5194/acp-18-17843-2018
    DORA PSI
  • Lehtipalo K, Yan C, Dada L, Bianchi F, Xiao M, Wagner R, et al.
    Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors
    Science Advances. 2018; 4(12): eaau5363 (9 pp.). https://doi.org/10.1126/sciadv.aau5363
    DORA PSI
  • Molteni U, Bianchi F, Klein F, El Haddad I, Frege C, Rossi MJ, et al.
    Formation of highly oxygenated organic molecules from aromatic compounds
    Atmospheric Chemistry and Physics. 2018; 18(3): 1909-1921. https://doi.org/10.5194/acp-18-1909-2018
    DORA PSI
  • Moschos V, Kumar NK, Daellenbach KR, Baltensperger U, Prévôt ASH, El Haddad I
    Source apportionment of brown carbon absorption by coupling ultraviolet-visible spectroscopy with aerosol mass spectrometry
    Environmental Science and Technology Letters. 2018; 5(6): 302-308. https://doi.org/10.1021/acs.estlett.8b00118
    DORA PSI
  • Nieminen T, Kerminen V-M, Petäjä T, Aalto PP, Arshinov M, Asmi E, et al.
    Global analysis of continental boundary layer new particle formation based on long-term measurements
    Atmospheric Chemistry and Physics. 2018; 18(19): 14737-14756. https://doi.org/10.5194/acp-18-14737-2018
    DORA PSI
  • Oikonomakis E, Aksoyoglu S, Ciarelli G, Baltensperger U, Prévôt ASH
    Low modeled ozone production suggests underestimation of precursor emissions (especially NOx) in Europe
    Atmospheric Chemistry and Physics. 2018; 18(3): 2175-2198. https://doi.org/10.5194/acp-18-2175-2018
    DORA PSI
  • Oikonomakis E, Aksoyoglu S, Wild M, Ciarelli G, Baltensperger U, Prévôt ASH
    Solar "brightening" impact on summer surface ozone between 1990 and 2010 in Europe - a model sensitivity study of the influence of the aerosol-radiation interactions
    Atmospheric Chemistry and Physics. 2018; 18(13): 9741-9765. https://doi.org/10.5194/acp-18-9741-2018
    DORA PSI
  • Oikonomakis E, Aksoyoglu S, Baltensperger U, Prevot ASH
    The impact of "Brightening" on surface O3 concentrations over Europe between 1990 and 2010
    In: Mensink C, Kallos G, eds. Air pollution modeling and its application XXV. Springer proceedings in complexity. Cham: Springer; 2018:31-36. https://doi.org/10.1007/978-3-319-57645-9_5
    DORA PSI
  • Pandolfi M, Alados-Arboledas L, Alastuey A, Andrade M, Angelov C, Artiñano B, et al.
    A European aerosol phenomenology – 6: scattering properties of atmospheric aerosol particles from 28 ACTRIS sites
    Atmospheric Chemistry and Physics. 2018; 18(11): 7877-7911. https://doi.org/10.5194/acp-18-7877-2018
    DORA PSI
  • Pieber SM, Kumar NK, Klein F, Comte P, Bhattu D, Dommen J, et al.
    Gas-phase composition and secondary organic aerosol formation from standard and particle filter-retrofitted gasoline direct injection vehicles investigated in a batch and flow reactor
    Atmospheric Chemistry and Physics. 2018; 18(13): 9929-9954. https://doi.org/10.5194/acp-18-9929-2018
    DORA PSI
  • Pieber SM, Kambolis A, Ferri D, Bhattu D, Bruns EA, Elsener M, et al.
    Mitigation of secondary organic aerosol formation from log wood burning emissions by catalytic removal of aromatic hydrocarbons
    Environmental Science and Technology. 2018; 52(22): 13381-13390. https://doi.org/10.1021/acs.est.8b04124
    DORA PSI
  • Schmale J, Henning S, Decesari S, Henzing B, Keskinen H, Sellegri K, et al.
    Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories
    Atmospheric Chemistry and Physics. 2018; 18(4): 2853-2881. https://doi.org/10.5194/acp-18-2853-2018
    DORA PSI
  • Stolzenburg D, Fischer L, Vogel AL, Heinritzi M, Schervish M, Simon M, et al.
    Rapid growth of organic aerosol nanoparticles over a wide tropospheric temperature range
    Proceedings of the National Academy of Sciences of the United States of America PNAS. 2018; 115(37): 9122-9127. https://doi.org/10.1073/pnas.1807604115
    DORA PSI
  • Vlachou A, Daellenbach KR, Bozzetti C, Chazeau B, Salazar GA, Szidat S, et al.
    Advanced source apportionment of carbonaceous aerosols by coupling offline AMS and radiocarbon size-segregated measurements over a nearly 2-year period
    Atmospheric Chemistry and Physics. 2018; 18(9): 6187-6206. https://doi.org/10.5194/acp-18-6187-2018
    DORA PSI
  • Zanatta M, Laj P, Gysel M, Baltensperger U, Vratolis S, Eleftheriadis K, et al.
    Effects of mixing state on optical and radiative properties of black carbon in the European Arctic
    Atmospheric Chemistry and Physics. 2018; 18(19): 14037-14057. https://doi.org/10.5194/acp-18-14037-2018
    DORA PSI
  • Zhou J, Bruns EA, Zotter P, Stefenelli G, Prévôt ASH, Baltensperger U, et al.
    Development, characterization and first deployment of an improved online reactive oxygen species analyzer
    Atmospheric Measurement Techniques. 2018; 11(1): 65-80. https://doi.org/10.5194/amt-11-65-2018
    DORA PSI
  • Zhou J, Zotter P, Bruns EA, Stefenelli G, Bhattu D, Brown S, et al.
    Particle-bound reactive oxygen species (PB-ROS) emissions and formation pathways in residential wood smoke under different combustion and aging conditions
    Atmospheric Chemistry and Physics. 2018; 18(10): 6985-7000. https://doi.org/10.5194/acp-18-6985-2018
    DORA PSI
  • Aksoyoglu S, Ciarelli G, El-Haddad I, Baltensperger U, Prévôt ASH
    Secondary inorganic aerosols in Europe: sources and the significant influence of biogenic VOC emissions, especially on ammonium nitrate
    Atmospheric Chemistry and Physics. 2017; 17(12): 7757-7773. https://doi.org/10.5194/acp-17-7757-2017
    DORA PSI
  • Bozzetti C, Sosedova Y, Xiao M, Daellenbach KR, Ulevicius V, Dudoitis V, et al.
    Argon offline-AMS source apportionment of organic aerosol over yearly cycles for an urban, rural, and marine site in northern Europe
    Atmospheric Chemistry and Physics. 2017; 17(1): 117-141. https://doi.org/10.5194/acp-17-117-2017
    DORA PSI
  • Bozzetti C, El Haddad I, Salameh D, Daellenbach KR, Fermo P, Gonzalez R, et al.
    Organic aerosol source apportionment by offline-AMS over a full year in Marseille
    Atmospheric Chemistry and Physics. 2017; 17(13): 8247-8268. https://doi.org/10.5194/acp-17-8247-2017
    DORA PSI
  • Bruns EA, Slowik JG, El Haddad I, Kilic D, Klein F, Dommen J, et al.
    Characterization of gas-phase organics using proton transfer reaction time-of-flight mass spectrometry: fresh and aged residential wood combustion emissions
    Atmospheric Chemistry and Physics. 2017; 17(1): 705-720. https://doi.org/10.5194/acp-17-705-2017
    DORA PSI
  • Ciarelli G, El Haddad I, Bruns E, Aksoyoglu S, Möhler O, Baltensperger U, et al.
    Constraining a hybrid volatility basis-set model for aging of wood-burning emissions using smog chamber experiments: a box-model study based on the VBS scheme of the CAMx model (v5.40)
    Geoscientific Model Development. 2017; 10(6): 2303-2320. https://doi.org/10.5194/gmd-10-2303-2017
    DORA PSI
  • Ciarelli G, Aksoyoglu S, El Haddad I, Bruns EA, Crippa M, Poulain L, et al.
    Modelling winter organic aerosol at the European scale with CAMx: evaluation and source apportionment with a VBS parameterization based on novel wood burning smog chamber experiments
    Atmospheric Chemistry and Physics. 2017; 17(12): 7653-7669. https://doi.org/10.5194/acp-17-7653-2017
    DORA PSI
  • Daellenbach KR, Stefenelli G, Bozzetti C, Vlachou A, Fermo P, Gonzalez R, et al.
    Long-term chemical analysis and organic aerosol source apportionment at nine sites in central Europe: source identification and uncertainty assessment
    Atmospheric Chemistry and Physics. 2017; 17(21): 13265-13282. https://doi.org/10.5194/acp-17-13265-2017
    DORA PSI
  • Frege C, Bianchi F, Molteni U, Tröstl J, Junninen H, Henne S, et al.
    Chemical characterization of atmospheric ions at the high altitude research station Jungfraujoch (Switzerland)
    Atmospheric Chemistry and Physics. 2017; 17(4): 2613-2629. https://doi.org/10.5194/acp-17-2613-2017
    DORA PSI
  • Furger M, Minguillón MC, Yadav V, Slowik JG, Hüglin C, Fröhlich R, et al.
    Elemental composition of ambient aerosols measured with high temporal resolution using an online XRF spectrometer
    Atmospheric Measurement Techniques. 2017; 10(6): 2061-2076. https://doi.org/10.5194/amt-10-2061-2017
    DORA PSI
  • Gordon H, Kirkby J, Baltensperger U, Bianchi F, Breitenlechner M, Curtius J, et al.
    Causes and importance of new particle formation in the present-day and preindustrial atmospheres
    Journal of Geophysical Research D: Atmospheres. 2017; 122(16): 8739-8760. https://doi.org/10.1002/2017JD026844
    DORA PSI
  • Kilic D, Brem BT, Klein F, El-Haddad I, Durdina L, Rindlisbacher T, et al.
    Characterization of gas-phase organics using proton transfer reaction time-of-flight mass spectrometry: aircraft turbine engines
    Environmental Science and Technology. 2017; 51(7): 3621-3629. https://doi.org/10.1021/acs.est.6b04077
    DORA PSI
  • Krapf M, Künzi L, Allenbach S, Bruns EA, Gavarini I, El-Haddad I, et al.
    Wood combustion particles induce adverse effects to normal and diseased airway epithelia
    Environmental Science: Processes and Impacts. 2017; 19(4): 538-548. https://doi.org/10.1039/c6em00586a
    DORA PSI
  • Platt SM, El Haddad I, Pieber SM, Zardini AA, Suarez-Bertoa R, Clairotte M, et al.
    Gasoline cars produce more carbonaceous particulate matter than modern filter-equipped diesel cars
    Scientific Reports. 2017; 7: 4926 (9 pp.). https://doi.org/10.1038/s41598-017-03714-9
    DORA PSI
  • Schmale J, Henning S, Henzing B, Keskinen H, Sellegri K, Ovadnevaite J, et al.
    Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition
    Scientific Data. 2017; 4: 170003 (26 pp.). https://doi.org/10.1038/sdata.2017.3
    DORA PSI
  • Stirnweis L, Marcolli C, Dommen J, Barmet P, Frege C, Platt SM, et al.
    Assessing the influence of NOx concentrations and relative humidity on secondary organic aerosol yields from α-pinene photo-oxidation through smog chamber experiments and modelling calculations
    Atmospheric Chemistry and Physics. 2017; 17(8): 5035-5061. https://doi.org/10.5194/acp-17-5035-2017
    DORA PSI
  • Tsagkogeorgas G, Roldin P, Duplissy J, Rondo L, Tröstl J, Slowik JG, et al.
    Evaporation of sulfate aerosols at low relative humidity
    Atmospheric Chemistry and Physics. 2017; 17(14): 8923-8938. https://doi.org/10.5194/acp-17-8923-2017
    DORA PSI
  • Wagner R, Yan C, Lehtipalo K, Duplissy J, Nieminen T, Kangasluoma J, et al.
    The role of ions in new particle formation in the CLOUD chamber
    Atmospheric Chemistry and Physics. 2017; 17(24): 15181-15197. https://doi.org/10.5194/acp-17-15181-2017
    DORA PSI
  • Wolf R, El-Haddad I, Slowik JG, Dällenbach K, Bruns E, Vasilescu J, et al.
    Contribution of bacteria-like particles to PM2.5 aerosol in urban and rural environments
    Atmospheric Environment. 2017; 160: 97-106. https://doi.org/10.1016/j.atmosenv.2017.04.001
    DORA PSI
  • Zotter P, Herich H, Gysel M, El-Haddad I, Zhang Y, Močnik G, et al.
    Evaluation of the absorption Ångström exponents for traffic and wood burning in the Aethalometer-based source apportionment using radiocarbon measurements of ambient aerosol
    Atmospheric Chemistry and Physics. 2017; 17(6): 4229-4249. https://doi.org/10.5194/acp-17-4229-2017
    DORA PSI