I would have thought this was obvious; every food processing plant has a form of air conditioning – for the obvious reason of preventing outside infection – yet this is not necessarily healthy for those that are working in its atmosphere…
Having worked for a short time in air-conditioned offices I can honestly say that I have never had so many respiratory or ‘cold’ complaints – none fortunately of great consequence – although colleagues were much more inflicted and were ‘sick’ as a result. Yet I remember being admonished for opening windows (supposedly ‘locked’ by authority) into the polluted Croydon air!
My mother spent a fortnight in hospital as a probable victim of legionnaire’s disease, having worked for most of her life in an air-conditioned office.
She is now, unsurprisingly a fresh air fiend!
This is of course no more than anecdotal evidence.
But perhaps I should suggest that basic anecdote is still some evidence.
And even basic logic suggests that fresh air helps to avoid a virus…