Although many industrial archaeology and heritage sites have now closed, or are about to close, for the winter, indoor ventilation to alleviate the spread of COVID becomes more important for those sites still open and for those sites where indoor working from volunteers over winter continues.
The latest UK Government guidance on ventilation at work can be found here: https://www.gov.uk/government/publications/covid-19-ventilation-of-indoor-spaces-to-stop-the-spread-of-coronavirus/ventilation-of-indoor-spaces-to-stop-the-spread-of-coronavirus-covid-19
Historic England’s guidance for adapting listed structures to be COVID compliant without damaging these protected buildings remains current and can be found here: https://historicengland.org.uk/coronavirus/reopening-heritage-locations/#bf06647e
This guidance is general and should be treated as a guide. In the event of conflict between any applicable legislation (including the health and safety legislation) and this guidance, the UK Government notes that the applicable legislation should prevail.