2023-12-30, Banholzer, Nicolas, Jent, Philipp, Bittel, Pascal, Zürcher, Kathrin, Furrer, Lavinia, Bertschinger, Simon, Weingartner, Ernest, Ramette, Alban, Egger, Matthias, Hascher, Tina, Fenner, Lukas

AbstractBackgroundUsing a multiple-measurement approach, we examined the real-world effectiveness of portable HEPA-air filtration devices (air cleaners) in a school setting.MethodsWe collected environmental (CO2, particle concentrations), epidemiological (absences related to respiratory infections), audio (coughing), and molecular data (bioaerosol and saliva samples) over seven weeks during winter 2022/2023 in two Swiss secondary school classes. Using a cross-over study design, we compared particle concentrations, coughing, and the risk of infection with vs without air cleaners.ResultsAll 38 students (age 13−15 years) participated. With air cleaners, mean particle con-centration decreased by 77% (95% credible interval 63%−86%). There were no differences in CO2levels. Absences related to respiratory infections were 22 without vs 13 with air cleaners. Bayesian modeling suggested a reduced risk of infection, with a posterior probability of 91% and a relative risk of 0.73 (95% credible interval 0.44−1.18). Coughing also tended to be less frequent (posterior probability 93%). Molecular analysis detected mainly non-SARS-CoV-2 viruses in saliva (50/448 positive), but not in bioaerosols (2/105 positive) or HEPA-filters (4/160). The detection rate was similar with vs without air cleaners. Spatiotemporal analysis of positive saliva samples identified several likely transmissions.ConclusionsAir cleaners improved air quality, showed a potential benefit in reducing respiratory infections, and were associated with less coughing. Airborne detection of non-SARS-CoV-2 viruses was rare, suggesting that these viruses may be more difficult to detect in the air. Future studies should examine the importance of close contact and long-range transmission, and the cost-effectiveness of using air cleaners.

2021-06-23, Keller, Alejandro, Specht, Patrick, Steigmeier, Peter, Weingartner, Ernest

2017, Schlag, Patrick, Rubach, Florian, Mentel, Thomas F., Reimer, David Thomas, Canonaco, Francesco, Henzing, Bas, Moerman, M., Otjes, R., Prévôt, André S.H., Rohrer, Franz, Rosati, B., Tillmann, Ralf, Weingartner, Ernest, Kiendler-Scharr, Astrid

Ambient measurements of PM₁aerosol chemical composition at Cabauw, the Netherlands, implicate higher ammonium concentrations than explained by the formation of inorganic ammonium salts. This additional particulate ammonium is called excess ammonium (e_NH4). Height profiles over the Cabauw Experimental Site for Atmospheric Research (CESAR) tower, of combined ground based and airborne aerosol mass spectrometric (AMS) measurements on a Zeppelin airship show higher concentrations ofe_NH4at higher altitudes compared to the ground. Through flights across the Netherlands, the Zeppelin based measurements furthermore substantiatee_NH4as a regional phenomenon in the planetary boundary layer. The excess ammonium correlates with mass spectral signatures of (di-)carboxylic acids, making a heterogeneous acid–base reaction the likely process of NH₃uptake. We show that this excess ammonium was neutralized by the organic fraction forming particulate organic ammonium salts. We discuss the significance of such organic ammonium salts for atmospheric aerosols and suggest that NH₃emission control will have benefits for particulate matter control beyond the reduction of inorganic ammonium salts.

2016, Gordon, Hamish, Sengupta, Kamalika, Rap, Alexandru, Duplissy, Jonathan, Frege, Carla, Williamson, Christina, Heinritzi, Martin, Simon, Mario, Yan, Chao, Almeida, João, Tröstl, Jasmin, Nieminen, Tuomo, Ortega, Ismael K., Wagner, Robert, Dunne, Eimear M., Adamov, Alexey, Amorim, Antonio, Bernhammer, Anne-Kathrin, Bianchi, Federico, Breitenlechner, Martin, Brilke, Sophia, Chen, Xuemeng, Craven, Jill S., Dias, Antonio, Ehrhart, Sebastian, Fischer, Lukas, Flagan, Richard C., Franchin, Alessandro, Fuchs, Claudia, Guida, Roberto, Hakala, Jani, Hoyle, Christopher R., Jokinen, Tuija, Junninen, Heikki, Kangasluoma, Juha, Kim, Jaeseok, Kirkby, Jasper, Krapf, Manuel, Kürten, Andreas, Laaksonen, Ari, Lehtipalo, Katrianne, Makhmutov, Vladimir, Mathot, Serge, Molteni, Ugo, Monks, Sarah A., Onnela, Antti, Peräkylä, Otso, Piel, Felix, Petäjä, Tuukka, Praplan, Arnaud P., Pringle, Kirsty J., Richards, Nigel A. D., Rissanen, Matti P., Rondo, Linda, Sarnela, Nina, Schobesberger, Siegfried, Scott, Catherine E., Seinfeld, John H., Sharma, Sangeeta, Sipilä, Mikko, Steiner, Gerhard, Stozhkov, Yuri, Stratmann, Frank, Tomé, Antonio, Virtanen, Annele, Vogel, Alexander Lucas, Wagner, Andrea C., Wagner, Paul E., Weingartner, Ernest, Wimmer, Daniela, Winkler, Paul M., Ye, Penglin, Zhang, Xuan, Hansel, Armin, Dommen, Josef, Donahue, Neil M., Worsnop, Douglas R., Baltensperger, Urs, Kulmala, Markku, Curtius, Joachim, Carslaw, Kenneth S.

A mechanism for the formation of atmospheric aerosols via the gas to particle conversion of highly oxidized organic molecules is found to be the dominant aerosol formation process in the preindustrial boundary layer over land. The inclusion of this process in a global aerosol model raises baseline preindustrial aerosol concentrations and could lead to a reduction of 27% in estimates of anthropogenic aerosol radiative forcing.

2022, Held, Andreas, Dellweg, Dominic, Köhler, Dieter, Pfaender, Stephanie, Scheuch, Gerhard, Schumacher, Stefan, Steinmann, Eike, Weingartner, Ernest, Weinzierl, Bernadett, Asbach, Christof

Die Bedeutung der Aerosolübertragung für das Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) wurde anfangs kontrovers diskutiert. Mit der Zeit haben sich zur Infektionsminderung jedoch neben Abstands- und Hygieneregeln auch aerosolphysikalisch begründete Maßnahmen wie das Tragen von Gesichtsmasken und Lüftung von Innenräumen als effektiv erwiesen. In einem interdisziplinären Workshop „Aerosol & SARS-CoV-2“ der Gesellschaft für Aerosolforschung (GAeF) in Kooperation mit der Deutschen Gesellschaft für Pneumologie und Beatmungsmedizin (DGP), dem Fachverband Allgemeine Lufttechnik im VDMA, der Gesellschaft für Virologie (GfV), der Gesundheitstechnischen Gesellschaft (GG) und der International Society for Aerosols in Medicine (ISAM) unter der Schirmherrschaft des Robert-Koch-Instituts (RKI) im März 2021 wurde der Forschungs- und Abstimmungsbedarf zu diesem Thema aufgegriffen. Wesentliche Grundlagen aus den verschiedenen Disziplinen sowie interdisziplinäre Perspektiven zur Aerosolübertragung von SARS-CoV-2 und zu infektionsmindernden Maßnahmen werden hier zusammengefasst. Abschließend werden offene Forschungsfragen und dringender Forschungsbedarf dargestellt.

2021-05-18, Keller, Alejandro, Specht, Patrick, Steigmeier, Peter, Weingartner, Ernest

Total aerosol carbonaceous mass (TC) is a major constituent of atmospheric fine aerosol not yet continuously monitored with adequate time resolution. Adding a TC measurement to existing measurement programs is crucial for comprehensive interpretation of the impact of aerosols. To fill this gap, we developed the “fast thermal carbon totalizator” (FATCAT) for long-term unsupervised monitoring of TC. FATCAT has been deployed since 2019 at diverse sites including the Jungfraujoch global GAW station (JFJ). FATCAT collects particles on a metallic filter, and subsequently heats it to 800°C under an oxidizing atmosphere. The limit of detection is LoD=0.2 µg of carbon (µg-C). At the reduced atmospheric pressure of the JFJ, which limits the sampling flow, this corresponds to TC=0.3 µg-C/m3 using a time resolution of two hours. We discuss our experience during the first two year of continuous TC measurements and the possibility of using our instrument to distinguish carbonaceous aerosol from different source using fast, 50 seconds, thermograms. This unique feature allows us to identify source specific fingerprints. Several high TC episodes during September 2020 at JFJ show the typical pattern for biomass combustion. Back trajectories attribute them to long-range transported emissions from Californian wildfires. Graphitic carbon from, e.g., local fossil fuel combustion evolves at higher temperatures. The data collected at the JFJ is already the longest produced TC dataset for this site without instrument related interruptions. The dataset generated by our instrument and post-analysis data products represent an improvement to the available measurement inventory. It can serve as quality control for other measurement systems. Prominently, measurements of eBC via MAAP or Aethalometer and organic mass using ToF-ACSM. TC data can be used in parallel to these devices as a quality check, and to warrant carbon mass closure and reduce systematic biases.

2016, Weingartner, Ernest, Jurányi, Zsofia, Egli, Daniel, Steigmeier, Peter, Burtscher, Heinz

This sensor detects volcanic ash particles and distinguishes them from cloud droplets. Operated on an airplane, this detector can quantify the exposure to hazardous refractory ash and the in-situ measurement is not biased by the presence of cloud particles. A volcanic eruption emits a significant amount of hazardous ash particles into the air. If the event is strong enough, the volcanic ash plume can reach high altitudes and can be a serious security risk for airplanes. We have developed a new prototype aerosol sensor for the reliable detection of volcanic ash. The envisaged application is the employment of this new technique on board of passenger aircraft. It allows in-situ monitoring of the airplane's exposure to volcanic ash. The challenge of this development is the requirement that the sensor can distinguish cloud droplets (or ice crystals) from the hazardous refractory ash particles. At aviation altitudes, water droplets and ice crystals are often present in the particle size region of the ash (1-20 micrometer) and their concentrations can reach the levels that are considered as the limits of the different volcanic ash contamination zones. Therefore, it is crucial that the sensor can differentiate between volcanic ash and water or ice particles. The sensor measures the scattered light intensities from individual particles outside of the airplane cabin through a glass window. The desired discrimination is achieved with two lasers operating at different wavelengths. Ash concentrations (in terms of number and mass) are derived, and the exposure of the airplane is recorded and transmitted in real time to the pilot. The volcanic ash detector was tested in the laboratory with various test aerosols and micrometer-sized water droplets. Then, ground-based outdoor measurements were conducted and the instrument response to mineral dust (a surrogate for volcanic ash) and natural cloud droplets (and ice crystals) was investigated. In a next step, this new technique will be tested in summer 2016 on-board of a research aircraft.

2021-09-13, Keller, Alejandro, Specht, Patrick, Steigmeier, Peter, Weingartner, Ernest

2021, Keller, Alejandro, Specht, Patrick, Steigmeier, Peter, Weingartner, Ernest

2016, Bianchi, Federico, Tröstl, Jasmin, Junninen, Heikki, Frege, Carla, Henne, Stephan, Hoyle, Christopher R., Molteni, Ugo, Herrmann, Erik, Adamov, Alexey, Bukowiecki, Nicolas, Chen, Xuemeng, Duplissy, Jonathan, Gysel, Martin, Hutterli, Manuel, Kangasluoma, Juha, Kontkanen, Jenni, Kürten, Andreas, Manninen, Hanna E., Münch, Steffen, Peräkylä, Otso, Petäjä, Tuukka, Rondo, Linda, Williamson, Christina, Weingartner, Ernest, Curtius, Joachim, Worsnop, Douglas R., Kulmala, Markku, Dommen, Josef, Baltensperger, Urs

From neutral to new Many of the particles in the troposphere are formed in situ, but what fraction of all tropospheric particles do they constitute and how exactly are they made? Bianchi et al report results from a high-altitude research station. Roughly half of the particles were newly formed by the condensation of highly oxygenated multifunctional compounds. A combination of laboratory results, field measurements, and model calculations revealed that neutral nucleation is more than 10 times faster than ion-induced nucleation, that particle growth rates are size-dependent, and that new particle formation occurs during a limited time window.