KKL: Aerosol study provides basis for further opening steps

An aerosol study by the Lucerne University of Applied Sciences and Arts and SCOEH shows that the ventilation efficiency in the KKL Luzern is good for the most part. A basis for further opening steps is thus given, as the cultural center writes.

The study shows that the airflow in the concert hall largely meets expectations and that airborne contamination is effectively dissipated in the audience area. The results also confirm that the risk of infection can be significantly minimized with consistent protective measures and that safe conditions can be created for visitors in the concert hall. These encouraging results, writes the KKL Luzern, would provide a very good scientific basis for the planned gradual opening steps over the next few months.

Together with its partners Lucerne Festival and Lucerne Symphony Orchestra, the KKL Luzern had commissioned the Lucerne University of Applied Sciences and Arts and the Swiss Centre for Occupational and Environmental Health SCOEH to investigate the risk of virus transmission in the concert hall from a ventilation perspective. The aim of the study was to provide a sound scientific basis for the discussion on the upcoming opening steps for the event industry. The concert hall of the KKL Luzern is equipped with a special ventilation system in which the supply air is fed in under the seats in the audience area. This is intended to remove the aerosols and other air pollutants emitted by the visitors more effectively than with pure mixed ventilation.

The measurements were carried out at the end of April in the presence of musicians and the audience (over 80 people in total) under realistic conditions. The ventilation effectiveness was investigated on the one hand with trace gases and on the other hand with a test aerosol in different areas of the hall, taking into account the ventilation and the activity of the room users (emitter and exposed person). The aerosols used were similar in size to those released by people breathing and speaking.

The study shows that air pollution in the public area is removed much more effectively than with purely mixed ventilation. Together with the generous design of the ventilation system and the large room volume, this results in a risk of infection that can be classified as low for the most part if the protection concept is adhered to. Only wind players and singers pose a slightly increased risk to other musicians singing or playing wind instruments without masks, as well as to the front row of the stalls. Simple protective masks with a retention efficiency of 25 percent were used as the basis for the study. With a certified mask (75 percent) or an FFP2 mask (95 percent), the residual risk can be significantly reduced.

The results of the study will be shared with the authorities and interested groups in the sense of an exchange of experiences. They have been incorporated into the test concert with over 500 guests of the Lucerne Symphony Orchestra, which was successfully held on Thursday with the highest level of safety for guests and musicians. The results will form an important basis for the Lucerne Festival from August 10 to September 12, 2021, the further opening of the KKL Luzern and the start of the season of the Lucerne Symphony Orchestra with its new chief conductor Michael Sanderling on October 20, 2021, writes the KKL in the press release.

For the staging of the Summer Festival, the Lucerne Festival has consciously decided to rely not only on the compulsory use of masks but also on a seating arrangement with safety distances, thus minimising the risk of infection. The KKL Luzern is using the study as a basis to enable further facilitations for all concert organisers from July onwards, in constant compliance with the applicable conditions, and to return step by step to normal operations.

The study also provides important information for the safe operation of large event venues in times of a pandemic, according to the KKL. The chosen measurement procedure could also be transferred to other event venues in Switzerland with similar technical features, so that they can be examined quickly and efficiently by experts.

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