There is now an entire section the Events and Attractions guidance on ventilation – we encourage you to read this and act on it, as it is really important. "Make sure there is an adequate supply of fresh air to enclosed spaces where there are people present. This can be natural ventilation (windows, doors and vents), mechanical ventilation (fans and ducts), or a combination of both. Identify any poorly ventilated spaces that are usually occupied (a CO2 monitor may help in some cases) and consider how to improve fresh air flow in these areas."
If people with Covid do unwittingly attend your rehearsal, good ventilation is your best defence against spread. Address this as the number one issue for your activity and with your venue.
Ventilation is about fresh air being brought into a space and potentially harmful aerosol particles being blown away. It is NOT about being freezing cold - you can put the heating on AND open the windows (though obviously this may increase your costs).
There are no hard and fast answers when it comes to ventilation. How well a space is ventilated will depend on many factors (see below). Ultimately the group has to assess the ventilation and decide on appropriate mitigations. It is worth remembering that:
- many spaces are designed to be well ventilated either through natural or mechanical ventilation – make sure you are using these tools, whatever they are in your venue, properly
- use common sense – we can generally tell when an area is poorly ventilated; conversely, if you’re sitting in a howling cross wind, the space is probably better ventilated than you need
- there are simple measures you can take to improve and manage ventilation – these will make a difference
- there are no absolute answers: even today’s outside weather will influence the air quality inside your hall, so next week you may have to ventilate more, or less, than this week.
The Health and Safety Executive (HSE) have an excellent resource to help assess ventilation risks and mitigate them. We recommend you read this and have pulled out some key points below.
Understand how well ventilated an area is: there will be several factors that go into that:
- Size of space – not just footprint, but height, too
- The number of people occupying the space
- The activity – singing does carry increased risks
- See the HSE guidance for more info.
Focus on identifying poorly ventilated areas:
- Where there isn’t any natural or mechanical ventilation
- If it feels stuffy or smells bad
- Using CO2 monitors – see below
- If an area is poorly ventilated and can’t be improved – consider how suitable it is for your activities
- See the HSE guidance for more info
Ensuring good ventilation: it’s important to maintain good ventilation in well-ventilated areas as well as improving in it in poorly ventilated areas.
- Natural ventilation: (i.e. doors, windows and vents):
- Take advantage of the natural ventilation by opening doors, windows and vents.
- Opening windows, doors and vents even for a brief period can help refresh the air.
- Ideally, they would be at opposite ends of a room to create cross flow.
- High up is good too as the heat of bodies (and radiators) in the room will make aerosols rise and be sucked out via high windows
- Doing a ‘purge’ and opening them fully will let most fresh air in to the room – this could be done before a rehearsal or during a break
- As the weather gets colder, we know natural ventilation becomes harder, but it is still important.
- Opening windows, doors and vents partially and for a short time can still make a difference.
- Cooler, windier weather increases natural ventilation – so you don’t have to open them as wide.
- Warm clothes and blankets can help.
- See the Health and Safety Executive (HSE) guidance for more info on:
- Mechanical ventilation: the important thing is that systems bring in new fresh air rather than recirculate air. Recirculation can increase the risk of transmission.
- Speak with the venue and make sure you understand howe the system works
- Systems should be set to maximise fresh air and minimise recirculation
- Recirculation units that do not bring in fresh air can remain in operation as long as there is an alternative supply of fresh air such as natural ventilation
- Fans should not be used in poorly ventilated areas but can be useful in the corners of rooms to prevent build-up of stagnant air, as long as there is also a supply of fresh air, such as natural ventilation
- See the HSE guidance for more info on mechanical ventilation
CO2 monitors
These are very helpful in determining the air quality in a room; CO2 presence does not mean there is also Covid in the room, but if there is a lot of CO2 it means the air quality is bad and therefore if there was anyone with Covid in the room, there could be a build-up of virus particles.
While CO2 monitors can be useful, they need to be used properly to get useful data. In larger spaces with high ceilings (e.g. churches) the air might not be fully mixed and so CO2 readings are less representative.
We recommend you read the Heath and Safety Executive guidance to understand how to use them – they have a useful table that shows how useful they are for different size rooms and activities.
We have pulled out some key info below.
- Measurements vary depending on occupants and activities and ventilation measures
- Regular readings throughout a day will give the best overall picture – try and work with the venue / other hirers to get a good set of readings
- Look for areas where people will be for an extended period of time and where there is no natural or mechanical ventilation
- Use them at head height near but not immediately in front of people
- Depending on the size of your space you may need more than one
If CO2 monitors are useful in your space, then you should be aiming for:
- levels consistently below 1500ppm
- keeping CO2 levels below 800ppm where there is continuous singing, as recommended in the Events guidance for England
If your readings don’t show these levels, then you need to look at increased ventilation measures. See natural and mechanical ventilation above and/or the following.
- Changing venue
- Rehearsing outdoors
- Reducing number of attendees
- Shortening length of rehearsals overall
- Shortening rehearsal sections (e.g. 30mins at a time instead of 45mins)
- Lengthening breaks
- Using face coverings
Although a ‘snapshot’ CO2 reading is not always useful, if you know ventilation levels in a venue are generally below 1500ppm/800ppm it can be useful to take measurements during a rehearsal and check levels are not rising. If they are, you can take short-term measures to improve levels such as taking a break, doing a purge, or reducing numbers.
Buying a CO2 monitor: You can buy CO2 monitors for around £85-100. Avoid the very cheapest as they are not much use.
| Making Music Corporate members test-meter offer members a discount on a CO2 monitor |
Air purifiers: You can buy stand-alone HEPA filter machines but note they are quite expensive (£250 approx.) plus for a room of any size you would need several. One will be enough for a large classroom, for example, approx. 140sqm.
More information on ventilation:
- Government guidance: Event guidance section on Ventilation (England)
- HSE guidance
- For more technical guidance including on different air conditioning systems, read the CIBSE guide
- British Occupational Hygiene Society ventilation tool
- British Occupational Hygiene Society ventilation FAQs
- Making Music Guest Speaker Webinar recording: Ventilation - how can it help manage the risk of Covid transmission?
