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Some interesting research news from Vienna!

The purpose of the study (27.05.2020) by the Medizinische Universitätat Wien at the request of the Austrian Choir Association was to investigate and document the formation and diffusion of aerosols and condensed water (drops) by choristers when singing without a mask, face mask and face shield.

Semi professional choristers as well as amateur choristers were examined.

The focus of this research was to photograph the airflow during singing as accurately as possible.

The singers were administered a mixture of oxygen and 0.9 percent saline solution that was atomized through tubes into the nostrils:

In a blackened room, behind each singer to left and right were very strong spotlights to visualize the outflow of the aerosols. The respective choir member was positioned between two black walls placed at a distance of about 162 centimeters. The camera was about 4 meters from the choristers. This setting was consistent with the setup in the experiment with the Vienna Philharmonic players.

The photographer took pictures of the choristers with a CANON full frame camera and a 70 mm lens during quiet breathing and singing.

The photographic representation of exhaled aerosols while singing was successful and is impressive. The images provide a very good representation of the approximate behaviour of air currents, even though the exact scientific measurements are missing and, most importantly, there is no evidence for the transmission of germs.

With 5 litres of oxygen per minute mist (= aerosol) was created in a small container with a mouthpiece. With small probes in the nostrils, this mist was also continuously added to the breath. This caused the aerosol to spread in the upper respiratory tract, which made it possible to visualize the distribution of the exhaled air in the backlight.

Normal quiet inhalation and exhalation showed a mist cloud of up to 0.5 m around the mouth and nose area of all choristers. On the other hand, a strong exhalation, mainly by the "bass", led to an expansion of the aerosol cloud of ~1.5 m!

During any type of singing the aerosol cloud around the head area remained unchanged. The expansion - especially forwards, with minimal amounts of the aerosol - extended to a maximum of ~0.9 m, but with certain singing techniques, there was increased swirl. Of course the wearing of any type of mask covering mouth and nose, could considerably reduce the expansion. However, the face shield allowed some of the cloud to escape downwards, which could not be observed with the mask.

An expansion of the exhaled air in choristers to more than ~1m is not expected! Deep inhalation and exhalation should be avoided, and the wearing of a mask covering mouth and nose should be considered in practising this profession.

07/03/2020 16:58 - NDR Kultur

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