However, Prof Michael Baker also believes there should be no travel in or out of Auckland while community transmission exists.
On Thursday, Queenstown Lakes Mayor Jim Boult called on the Government to revise the "excessive" social distancing requirements that, at present, mean Air New Zealand can sell only 50% of its seats on a turboprop aircraft, the likes of which service Queenstown from Christchurch, and 65% on A320s, which are put on longer routes.
That was having a massive impact on the national carrier as well as the travelling public, given flights were more expensive and demand was unsatisfied.
Mr Boult said the district was in an "economically desperate situation" and needed the additional travellers a relaxing of distancing requirements would bring.
The Ministry of Health declined to comment yesterday, but Prof Baker said "ideally" both social distancing and masks would be used, but if public transport was not able to be used efficiently, then masks — which provided both "source control" and a protective barrier — should suffice.
Further, on aircraft — particularly jets — the ventilation system was effective, moving air up and down rather than forward and back, and through a HEPA filter to remove fine droplets.
"So there hasn’t been very much transmission on aircraft — it has happened — but that’s part of the reason why aircraft are, probably, relatively safe as an indoor environment.
"There’s no question transmission can happen in that environment, but if everyone’s wearing masks, and people are seated, then that’s going to provide a very good line of protection."
However, Prof Baker said the Government needed to "fine tune" the alert level system so it was "more nuanced" to include "actual practical rules" and introduce other levels, for example, 1.5.
"It’s just at the moment the system is too crude.
"We’d argue that there shouldn’t be travel in and out of Auckland while there’s active transmission, but that’s obviously a more sensitive subject — whether that should be a feature of 2.5 or not, we have argued that it should be."
