Search Results
Ultrafine particles in cities
2014, Kumar, Prashant, Morawska, Lidia, Birmili, Wolfram, Paasonen, Pauli, Hu, Min, Kulmala, Markku, Harrison, Roy M., Norford, Leslie, Britter, Rex
Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts.
Felduntersuchungen von Budgets und Konversionen organischer Partikelinhaltsstoffe in troposphärischen Wolkenprozessen (FEBUKO): Projektabschlussbericht ; Teilprojekte: IfT-1: Physiko-chemische Charakterisierung von Luft, Partikeln und Wolkenwasser in Wolkenexperimenten; IfT-2: Phasenaufteilung von biogenen und anthropogenen organischen Aerosolkomponenten und flüchtiger organischer Substanzen in Wolken; BTU: Anteil und Modifikation organischer und reaktiver Substanzen in der Aerosol- und Wolkenwasserphase während des Wolkendurchganges; ZUF: Aerosolpartikel und Wolkentropfen als Quelle von Peroxyradikalen und Wasserstoffperoxid - Photochemie im atmosphärischen Mehrphasensystem durch organische Chromophore; TUD: Bestimmung organischer Spezies (Aldehyde, Ketone, Carbonsäuren) in Einzeltropfen zur Bestimmung der zugehörigen Aerosolgrößen und des Wolkenscavengings
2004, Herrmann, Hartmut, Wiedensohler, Alfred, Mertes, Stephan, Wieprecht, Wolfgang, Jaeschke, Wolfgang, Bächmann, Knut
[no abstract available]
Different pathways of the formation of highly oxidized multifunctional organic compounds (HOMs) from the gas-phase ozonolysis of β-caryophyllene
2016, Richters, Stefanie, Herrmann, Hartmut, Berndt, Torsten
The gas-phase mechanism of the formation of highly oxidized multifunctional organic compounds (HOMs) from the ozonolysis of β-caryophyllene was investigated in a free-jet flow system at atmospheric pressure and a temperature of 295 ± 2 K. Reaction products, mainly highly oxidized RO2 radicals containing up to 14 oxygen atoms, were detected using chemical ionization – atmospheric pressure interface – time-of-flight mass spectrometry with nitrate and acetate ionization. These highly oxidized RO2 radicals react with NO, NO2, HO2 and other RO2 radicals under atmospheric conditions forming the first-generation HOM closed-shell products. Mechanistic information on the formation of the highly oxidized RO2 radicals is based on results obtained with isotopically labelled ozone (18O3) in the ozonolysis reaction and from hydrogen/deuterium (H/D) exchange experiments of acidic H atoms in the products. The experimental findings indicate that HOM formation in this reaction system is considerably influenced by the presence of a double bond in the RO2 radicals primarily formed from the β-caryophyllene ozonolysis. Three different reaction types for HOM formation can be proposed, allowing for an explanation of the detected main products: (i) the simple autoxidation, corresponding to the repetitive reaction sequence of intramolecular H-abstraction of a RO2 radical, RO2 → QOOH, and subsequent O2 addition, next forming a peroxy radical, QOOH + O2 → R′O2; (ii) an extended autoxidation mechanism additionally involving the internal reaction of a RO2 radical with a double bond forming most likely an endoperoxide and (iii) an extended autoxidation mechanism including CO2 elimination. The individual reaction steps of the reaction types (ii) and (iii) are uncertain at the moment. From the product analysis it can be followed that the simple autoxidation mechanism accounts only for about one-third of the formed HOMs. Time-dependent measurements showed that the HOM formation proceeds at a timescale of 3 s or less under the concentration regime applied here. The new reaction pathways represent an extension of the mechanistic understanding of HOM formation via autoxidation in the atmosphere, as recently discovered from laboratory investigations on monoterpene ozonolysis.
EFEU - Einfluß von Vegetationsfeuern auf die Zusammensetzung und die Zirkulation der Atmosphäre : Laboruntersuchungen und numerische Simulationen: Der Einfluß von Biomassenverbrennung auf die Energetik, die chemische Zusammensetzung, die Wolken- und die Niederschlagsbildung und den Transport in der Atmosphäre ; Abschlussbericht zum AFO2000-Verbundprojekt
2005, Wurzler, Sabine, Simmel, Martin
[no abstract available]
Associations between air temperature and cardio-respiratory mortality in the urban area of Beijing, China: a time-series analysis
2011, Liu, Liqun, Breitner, Susanne, Pan, Xiaochuan, Franck, Ulrich, Leitte, Arne Marian, Wiedensohler, Alfred, von Klot, Stephanie, Wichmann, H-Erich, Peters, Annette, Schneider, Alexandra
Background: Associations between air temperature and mortality have been consistently observed in Europe and the United States; however, there is a lack of studies for Asian countries. Our study investigated the association between air temperature and cardio-respiratory mortality in the urban area of Beijing, China. Methods: Death counts for cardiovascular and respiratory diseases for adult residents (≥15 years), meteorological parameters and concentrations of particulate air pollution were obtained from January 2003 to August 2005. The effects of two-day and 15-day average temperatures were estimated by Poisson regression models, controlling for time trend, relative humidity and other confounders if necessary. Effects were explored for warm (April to September) and cold periods (October to March) separately. The lagged effects of daily temperature were investigated by polynomial distributed lag (PDL) models. Results: We observed a J-shaped exposure-response function only for 15-day average temperature and respiratory mortality in the warm period, with 21.3°C as the threshold temperature. All other exposure-response functions could be considered as linear. In the warm period, a 5°C increase of two-day average temperature was associated with a RR of 1.098 (95% confidence interval (95%CI): 1.057-1.140) for cardiovascular and 1.134 (95%CI: 1.050-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.040 (95%CI: 0.990-1.093) for cardiovascular mortality. In the cold period, a 5°C increase of two-day average temperature was associated with a RR of 1.149 (95%CI: 1.078-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.057 (95%CI: 1.022-1.094) for cardiovascular mortality. The effects remained robust after considering particles as additional confounders. Conclusions: Both increases and decreases in air temperature are associated with an increased risk of cardiovascular mortality. The effects of heat were immediate while the ones of cold became predominant with longer time lags. Increases in air temperature are also associated with an immediate increased risk of respiratory mortality.
Reservoiraufteilung von Ruß, organischen Bestandteilen, Gesamtkohlenstoff, löslichen Substanzen und Aerosolpartikeln (Anzahl und Masse) in der Tropfen- und Zwischenraumphase von Wolken : Abschlussbericht
2002, Mertes, Stephan, Schwarzenböck, A., Brüggemann, E., Gnauk, T., Dippel, B.
[no abstract available]