New rules have been put in place for people in New Zealand's COVID-19 managed isolation and quarantine (MIQ) facilities following the problems at Auckland's Pullman Hotel.
The new advice is "keep your windows open".
Newshub has seen a memo given to returnees at some Auckland hotels saying it'll decrease the possibility of coronavirus spreading.
The Holiday Inn is one of the more comfortable and well-ventilated isolation hotels. It boasts sub-tropical garden surrounds and windows and balconies that open to fresh air.
Returnees like Riley Elliot have been told "keep your windows open", but "close them when opening your door" when leaving for exercise or to talk to a nurse.
"The interesting part is to stop air being transmitted into the hallways, is to then shut your doors and windows before you open your door," he said.
So multiple times a day, Elliot now shuts the sliding door before opening the door into the hallway.
The intention of the new window policy is clear. The memo states it's "to decrease the possibility of the virus spreading from room to room or to staff" at the hotel.
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Professor Michael Baker, an epidemiologist who works for Otago University's Department of Public Health, says proper ventilation in our MIQs is crucial.
"You can imagine stuffy corridors and rooms in hotels is an environment where the virus could be transmitted in aerosols, and that may explain some of the border failures we've had in New Zealand," he said.
The new rules come about due to failures at the Pullman, where people got the virus from one another. Officials still don't know exactly how that occurred.
But it's possible those that caught it were in the same corridor or elevator shortly after one another.
"Therefore the droplets could have still been in the air and that's one of the possibilities they can't discount. That's why they're making changes around the airflows in the facilities to avoid that," COVID-19 Response Minister Chris Hipkins said.
Returnees at the Naumi Hotel have also been told to keep "windows open", but other hotels don't have opening windows at all.
"They didn't get one of these [memos] because they don't have windows to open," Elliot said.
Hipkins says returnees in these facilities shouldn't be worried their airflow isn't as good.
"We've been looking at the air flows in all the managed isolation facilities and the guidance will depend on the air conditioning systems that they have," he said.
Prof Baker says it's important to remember these are hotels, not purpose-built quarantine facilities.
However he warns airborne transmission is a risk - much more than the virus being left on surfaces, which he says actually play a very limited role, if any, in transmission.
The Ministry of Business, Innovation and Employment was unable to say how many hotels had been given the 'shut windows' memo to hand out to returnees.
But a spokesperson said the rule change would be implemented at all facilities "in due course, where appropriate".
A spokesperson said the changes were made out of "an abundance of caution".
"Although this change was prompted by events at the Pullman, the advice of health and ventilation specialists was that it made sense to apply it elsewhere at the same time," they said.
However, the spokesperson said returnees without windows that open will not be impacted, as the air being blown into the corridor has "already been mitigated with a shut window".