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Ventilation: how can it help manage the risk of Covid transmission? (online event)19/11/2021

 Bernard Marley  attended and reported on this Webinar - as hosted by Making Music.

 It was was presented in three sections:

 *   The Physics of air flow and ventilation. Colin Avon

 *   Medical aspects regarding impacts on singing. Dr Jackie Carnell

 *   Sociological aspects of distancing / singing. Professor Robert Dingwall

 The general points picked out from all three speakers were as follows:

 Technical matters:

 *   To fully ventilate a typical church or church hall it is recommended that the air is fully changed 4-6 times per hour. (This rate is the same as that used in Supermarkets with a subsequent low level of Covid infection - in modern stores that have been closely monitored using mechanical ventilation.)

*   Although modern ventilation methods are not readily available in an old church / church hall, a single window opened at either end of a hall would be sufficient to create the desired air exchange. Delegates described the method as a trickling ventilation.

*   If you are all cold with the windows / doors wide open according to Colin Avon, "there is too much ventilation" - there should only be a minor reduction in temperature in the hall.

*   The heating can and should be on in the hall - as this creates the heat differential which promotes the airflow.

*   Despite a lot of recent discussion on the use of CO₂ monitors to monitor the freshness of the air within a hall, the CO₂ results are not reliable enough for CO₂ monitors to have any practical value. (You can't sample enough places in the hall frequently enough to get a meaningful result.

*   Similarly, air filters that are being sold on Amazon and the like are virtually useless, as they simply can't handle the amount of air in the time given.

*   More importantly - from the estimates given by Colin, for a typical church hall with a high ceiling  (20m by 15m by 10m high) the available air would be fresh enough to last 40 hours for 50 people.

*   The computer models used in the media - to describe the direction and flow of air as we breathe out, are somewhat false - as they were based on experiments using stylized robotic pumps rather than actual human beings. The models all suggest we breathe out horizontally whereas when we breathe, the hot breath will immediately rise.

*   The positioning of choir singers one behind each other reduced the impact of a direct intake of air from a singer who is stood behind you.

 Health and Social aspects:

 *   At some point we have to accept that our strategy will become one of how to live with Covid. What are the Risks of contracting the disease versus the impact on the social / mental problems of continued isolation. What is a tolerable risk?

*   The medical profession is anticipating a massive increase in all respiratory diseases this winter due to last year's lull in flu and colds. We should be telling all choir members with any type of Infectious respiratory disease not to attend if they have any new symptoms (Flu, colds and Covid).

*   Car sharing could be a bigger issue for some choir members than being at the rehearsal

*   Road accidents on the way to and from rehearsals - will return to being the biggest risk for choir members.

*   All choirs should promote an active and ongoing discussion on the above health and social aspects.