Search Results
Preventing airborne transmission of SARS-CoV-2 in hospitals and nursing homes
2020, Ahlawat, Ajit, Mishra, Sumit Kumar, Birks, John W., Costabile, Francesca, Wiedensohler, Alfred
[No abstract available]
Long-term trends of black carbon and particle number concentration in the lower free troposphere in Central Europe
2021, Sun, Jia, Hermann, Markus, Yuan, Ye, Birmili, Wolfram, Collaud Coen, Martine, Weinhold, Kay, Madueño, Leizel, Poulain, Laurent, Tuch, Thomas, Ries, Ludwig, Sohmer, Ralf, Couret, Cedric, Frank, Gabriele, Brem, Benjamin Tobias, Gysel-Beer, Martin, Ma, Nan, Wiedensohler, Alfred
Background: The implementation of emission mitigation policies in Europe over the last two decades has generally improved the air quality, which resulted in lower aerosol particle mass, particle number, and black carbon mass concentration. However, little is known whether the decreasing particle concentrations at a lower-altitude level can be observed in the free troposphere (FT), an important layer of the atmosphere, where aerosol particles have a longer lifetime and may affect climate dynamics. In this study, we used data from two high-Alpine observatories, Zugspitze-Schneefernerhaus (ZSF) and Jungfraujoch (JFJ), to assess the long-term trends on size-resolved particle number concentrations (PNCs) and equivalent black carbon (eBC) mass concentration separated for undisturbed lower FT conditions and under the influence of air from the planetary boundary layer (PBL) from 2009 to 2018. Results: The FT and PBL-influenced conditions were segregated for both sites. We found that the FT conditions in cold months were more prevalent than in warm months, while the measured aerosol parameters showed different seasonal patterns for the FT and PBL-influenced conditions. The pollutants in the PBL-influenced condition have a higher chance to be transported to high-altitudes due to the mountainous topography, leading to a higher concentration and more distinct seasonal variation, and vice versa. The long-term trends of the measured aerosol parameters were evaluated and the decreased aerosol concentrations were observed for both FT and PBL-influenced conditions. The observed decreasing trends in eBC concentration in the PBL-influenced condition are well consistent with the reported trends in total BC emission in Germany and Switzerland. The decreased concentrations in the FT condition suggest that the background aerosol concentration in the lower FT over Central Europe has correspondingly decreased. The change of back trajectories in the FT condition at ZSF and JFJ was further evaluated to investigate the other possible drivers for the decreasing trends. Conclusions: The background aerosol concentration in the lower FT over Central Europe has significantly decreased during 2009–2018. The implementation of emission mitigation policies is the most decisive factor and the decrease of the regional airmass occurrence over Central Europe also has contributed to the decreasing trends. © 2021, The Author(s).
Phenomenology of ultrafine particle concentrations and size distribution across urban Europe
2023, Trechera, Pedro, Garcia-Marlès, Meritxell, Liu, Xiansheng, Reche, Cristina, PĂ©rez, NoemĂ, Savadkoohi, Marjan, Beddows, David, Salma, Imre, Vörösmarty, MĂ¡tĂ©, Casans, Andrea, Casquero-Vera, Juan AndrĂ©s, Hueglin, Christoph, Marchand, Nicolas, Chazeau, Benjamin, Gille, GrĂ©gory, Kalkavouras, Panayiotis, Mihalopoulos, Nikos, Ondracek, Jakub, Zikova, Nadia, Niemi, Jarkko V., Manninen, Hanna E., Green, David C., Tremper, Anja H., Norman, Michael, Vratolis, Stergios, Eleftheriadis, Konstantinos, GĂ³mez-Moreno, Francisco J., Alonso-Blanco, Elisabeth, Gerwig, Holger, Wiedensohler, Alfred, Weinhold, Kay, Merkel, Maik, Bastian, Susanne, Petit, Jean-Eudes, Favez, Olivier, Crumeyrolle, Suzanne, Ferlay, Nicolas, Martins Dos Santos, Sebastiao, Putaud, Jean-Philippe, Timonen, Hilkka, Lampilahti, Janne, Asbach, Christof, Wolf, Carmen, Kaminski, Heinz, Altug, Hicran, Hoffmann, Barbara, Rich, David Q., Pandolfi, Marco, Harrison, Roy M., Hopke, Philip K., Petäjä, Tuukka, Alastuey, AndrĂ©s, Querol, Xavier
The 2017–2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus. The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping. Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation. PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this size fraction.