@article{AlsaadSchaelteSchneeweissetal.,
  author    = {Alsaad, Hayder and Sch{\"a}lte, Gereon and Schneeweiß, Mario and Becher, Lia and Pollack, Moritz and Gena, Amayu Wakoya and Schweiker, Marcel and Hartmann, Maria and Voelker, Conrad and Rossaint, Rolf and Irrgang, Matthias},
  title     = {The Spread of Exhaled Air and Aerosols during Physical Exercise},
  series = {Journal of Clinical Medicine},
  volume    = {2023},
  journal   = {Journal of Clinical Medicine},
  number    = {Volume 12, issue 4, article 1300},
  publisher = {Basel},
  address   = {MDPI},
  doi       = {10.3390/jcm12041300},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230208-49262},
  pages     = {20},
  abstract  = {Physical exercise demonstrates a special case of aerosol emission due to its associated elevated breathing rate. This can lead to a faster spread of airborne viruses and respiratory diseases. Therefore, this study investigates cross-infection risk during training. Twelve human subjects exercised on a cycle ergometer under three mask scenarios: no mask, surgical mask, and FFP2 mask. The emitted aerosols were measured in a grey room with a measurement setup equipped with an optical particle sensor. The spread of expired air was qualitatively and quantitatively assessed using schlieren imaging. Moreover, user satisfaction surveys were conducted to evaluate the comfort of wearing face masks during training. The results indicated that both surgical and FFP2 masks significantly reduced particles emission with a reduction efficiency of 87.1\% and 91.3\% of all particle sizes, respectively. However, compared to surgical masks, FFP2 masks provided a nearly tenfold greater reduction of the particle size range with long residence time in the air (0.3-0.5 μm). Furthermore, the investigated masks reduced exhalation spreading distances to less than 0.15 m and 0.1 m in the case of the surgical mask and FFP2 mask, respectively. User satisfaction solely differed with respect to perceived dyspnea between no mask and FFP2 mask conditions.},
  subject      = {Sport},
  language  = {en}
}
@article{BecherGenaAlsaadetal.,
  author    = {Becher, Lia and Gena, Amayu Wakoya and Alsaad, Hayder and Richter, Bernhard and Spahn, Claudia and V{\"o}lker, Conrad},
  title     = {The spread of breathing air from wind instruments and singers using schlieren techniques},
  series = {Indoor Air},
  volume    = {2021},
  journal   = {Indoor Air},
  number    = {volume 31, issue 6},
  publisher = {Wiley Blackwell},
  address   = {Oxford},
  doi       = {10.1111/ina.12869},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220209-45817},
  pages     = {1798 -- 1814},
  abstract  = {The spread of breathing air when playing wind instruments and singing was investigated and visualized using two methods: (1) schlieren imaging with a schlieren mirror and (2) background-oriented schlieren (BOS). These methods visualize airflow by visualizing density gradients in transparent media. The playing of professional woodwind and brass instrument players, as well as professional classical trained singers were investigated to estimate the spread distances of the breathing air. For a better comparison and consistent measurement series, a single high note, a single low note, and an extract of a musical piece were investigated. Additionally, anemometry was used to determine the velocity of the spreading breathing air and the extent to which it was quantifiable. The results showed that the ejected airflow from the examined instruments and singers did not exceed a spreading range of 1.2 m into the room. However, differences in the various instruments have to be considered to assess properly the spread of the breathing air. The findings discussed below help to estimate the risk of cross-infection for wind instrument players and singers and to develop efficacious safety precautions, which is essential during critical health periods such as the current COVID-19 pandemic.},
  subject      = {Covid-19},
  language  = {en}
}
@article{GenaVoelkerSettles,
  author    = {Gena, Amayu Wakoya and V{\"o}lker, Conrad and Settles, Gary},
  title     = {Qualitative and quantitative schlieren optical measurement of the human thermal plume},
  series = {Indoor Air},
  volume    = {2020},
  journal   = {Indoor Air},
  number    = {volume 30, issue 4},
  publisher = {John Wiley \& Sons},
  doi       = {10.1111/ina.12674},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200709-41936},
  pages     = {757 -- 766},
  abstract  = {A new large-field, high-sensitivity, single-mirror coincident schlieren optical instrument has been installed at the Bauhaus-Universit{\"a}t Weimar for the purpose of indoor air research. Its performance is assessed by the non-intrusive measurement of the thermal plume of a heated manikin. The schlieren system produces excellent qualitative images of the manikin's thermal plume and also quantitative data, especially schlieren velocimetry of the plume's velocity field that is derived from the digital cross-correlation analysis of a large time sequence of schlieren images. The quantitative results are compared with thermistor and hot-wire anemometer data obtained at discrete points in the plume. Good agreement is obtained, once the differences between path-averaged schlieren data and planar anemometry data are reconciled.},
  subject      = {Raumklima},
  language  = {en}
}