Experts are warning Delta could easily spread through schools, buses, offices - even our MIQs - if ventilation systems aren't brought up to scratch urgently.
We used to think COVID-19 mostly spread through droplets on surfaces, picked up by touch - hence the mantra of 'wash your hands' - but now aerosols are considered the dominant form of transmission.
Smoke and vapour are visible aerosols but you exhale invisible aerosols with every breath and they linger longer than droplets. They can also be recirculated through air conditioning with COVID-19 clinging to them.
An article in Science last week found "airborne transmission of pathogens has been vastly underappreciated" for many viruses including COVID-19. It also found some of our attempts to control droplets have been making it worse - plexiglass barriers can trap aerosols and actually increase transmission.
"These little tiny particles can hang around for even hours if there isn't proper ventilation," analytical chemist Dr Joel Rindelaub told Newshub Nation.
So with mounting evidence that good ventilation is critical, Dr Rindelaub warns the standard ventilation systems in areas with a high risk of transmission are not up to scratch - particularly in the face of Delta.
"Ventilation systems - air conditioning systems - are designed for comfort and for people's well-being, but they're not designed to cope with pandemics and infectious diseases."
Some environments are worse than others and at some point our tamariki will go back to crowded classrooms.
"We know that schools are actually virus factories," says Dr Rindelaub.
"This is one of the areas we need to have as good a ventilation as possible to make sure that we aren't adding transmission events or creating hot spots of outbreaks."
Jackson Engineering managing director Lance Jimmieson says previous design decisions in schools are now working against us.
"A lot of schools have concentrated in the past on heating systems and really keeping the school closed up so that we don't lose the heat. And that is counter to what we need to do to ventilate the space and make the space safe."
Dr Rindelaub argues good ventilation in homes, schools and businesses isn't just useful for fighting COVID-19, it can help control the spread of other illnesses such as RSV.
"It's going to have a lot more other benefits as far as respiratory ailments that we do see here in New Zealand, more than we should. So it's going to have long-lasting effects that will keep us self safe well beyond COVID-19."
At the very least, he says, teachers will need to open the windows.
"Of course, it's not always going to be possible to do that depending on the outdoor conditions, but that would be a good start to help get better airflow within those classrooms."
And schools aren't the only area at risk, with one bus driver - who wished to remain anonymous - telling Newshub Nation nothing was being done to combat the spread of COVID-19 through the air in his vehicle.
"Most of the time there are no windows on the buses. You can expect drivers' windows on some buses but not all of them."
Drivers' concerns about their buses are particularly salient considering an enclosed vehicle transporting aircrew is how the outbreak started in Australia before spreading to New Zealand.
"What they could do is have a portable air recirculater added to the bus if they can't open the windows," suggests Dr Rindelaub.
"Of course, windows would be an easy first choice there… and of course, we want our drivers to have the best protection. So that would mean N95 masks."
Experts are also concerned about ventilation in MIQ, where last month at JetPark, the virus spread across the hallway between rooms despite their doors both being open for only seconds.
"If you were to purpose-build an isolation facility, it wouldn't look anything like a current hotel... they are pretty makeshift for a containment facility," says Jimmieson.
"It is a real risk. We need to have cleaner environments. If we go back early and people are infected, the systems at the moment are very likely to spread that quite well."
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