the air purity inside a modern airliner is similar to that in an operating theatre
The air changes may be as many, and the filters may be almost as good as in a theatre air handling unit, but purity is quite different as it includes fumes etc which are not filtered. Purity isnt the issue, it is the virus particle. The need is to remove virus in aerosol in the air and that is where data is lacking. In an operating theatre we wear full PPE and deep clean between cases because we recognise that staff can spread virus to each other by droplets and aerosol because they are working indoors and in close proximity to each other - just like an aircraft.
Masks can be of use to stop someone unwittingly (or otherwise?) being on board with this 'thing' from spreading it to anyone in their immediate vicinity
No, the masks passengers wear reduce but do not eliminate the virus getting into the air. That is why we wear FFP3 masks or respirators in operating theatres so we dont inhale the aerosol potentially produced by others. Importantly, the masks passengers wear give little or no protection to the wearer
So an aircraft is only 'safe' if you guarantee nobody is shedding virus (in practice that means 14 days isolation, a PCR swab
and nobody from a high attack rate area - impossible) and everyone is trained and fitted with full PPE. Again impossible.
the risk of contracting virus on aeroplanes is much, much lower than in all sorts of other activities that people seem quite happy to want to take part in.
Depends on the activity and the risk you are prepared to take
