Airborne COVID-19 and the future of indoor Australia

by Ben Ice
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As our nation hits vaccine targets and reopens, concerns remain about the airborne spread of COVID-19 and the health of our indoor air.

Putting hard lockdowns behind them, Sydney and Melbourne are now underway with their roadmaps. Vaccine targets are being knocked down everywhere and we are grasping some form of ‘normal’. But, for many scientists, medical professionals and facility managers, there is an alarming oversight. Focusing on vaccine rates, along with the ongoing COVID-safe measures, such as social distancing, sanitising and profuse surface cleaning, means forgetting one major measure: ventilation. 

Airborne spread and the speed of the Delta variant have exposed major gaps in our armour and pose a continued risk of outbreaks as we open up. So how did we get here, and how can we become safer and better prepared?

Missed lessons of 2020

As the coronavirus ravaged communities in March 2020, the world rushed to slow the spread. Opportunists stocked their garages with sanitiser hoping to cash in on the high demand, supermarket shelves were picked clean and we were told to wash our hands and stop touching our faces. As time wore on, these panicked measures began to take a more official shape as COVID-safe guidelines. There were sanitisers at every store, social distancing in public spaces and buildings, and rigorous and continual cleaning requirements of any and all surfaces. These measures were based on the understanding, pushed by the World Health Organisation (WHO), that the virus was spread by droplets and contact. And, when combined with lockdowns, restrictions, testing and contact tracing, the measures worked. 

But they ignored – and in some cases denied – airborne transmission by aerosols. WHO did not include airborne spread in its coronavirus details until late April this year.  Why the delay?

Bruce Milthorpe, former Dean of Science at University of Technology Sydney with a background as a biochemist and biomaterials science, puts it down to a sort of inertia. Recommendations for COVID-19 management “have all basically taken what has worked for other diseases, other pandemics and things which largely haven’t included aerosol transmission,” he says.

“Basically, we’re working on what’s worked in the past rather than saying ‘Hey, there’s something really bad here, we need to change the way that we work.”

In fact, scientists knew about airborne spread early. In July 2020, Distinguished Professor Lidia Morawska, of Queensland University of Technology’s School of Earth and Atmospheric Science, led a team of 239 scientists writing an open letter appealing to the medical community and relevant national and international bodies to address airborne coronavirus transmission. The letter set in motion a global shift in our understanding of this virus and how it’s spread. It’s an ongoing conversation and one that is arguably still lagging. It was the 2021 emergence of the rapid-spreading Delta variant that really pushed us to move on ventilation.

Delta blues

The Delta variant opened up a ‘pandemic of the unvaccinated’ in early vaccination front-running nations like the UK and the US. At home, it sent states back into lockdown after months of relative calm. Ultimately, it forced Victoria and New South Wales to abandon zero-case strategies altogether and only showed signs of abating when high vaccination targets were hit. This strand, which travels between those it infects much faster than any previous variants, has exposed the shortsightedness of many of our previous control measures.

“It has been recognised that aerosol transmission is a significant factor now, especially for Delta,” says Milthorpe. “It seems to be much more transmissible by aerosols.

“The lockdown had an effect,” he says of Sydney’s outbreak, “it just wasn’t as good as it had been… and it’s because we haven’t recognised aerosol transmission – and the contact tracing and everything we do doesn’t recognise, or is not set in place for, significant amounts of aerosol transmission.”

The air we breathe

Morawska is an internationally recognised air quality and health expert. Since leading the scientists in their open letter to WHO, she was named as one of Time magazine’s 100 Most Influential People of 2021 and is an executive member of OzSAGE, a multidisciplinary, independent network of Australian experts offering well-researched advice on COVID-19 exit strategies. She’s pleased airborne transmission gets talked about, but says there needs to be more clarity on the messaging, and that more work needs to be done.

WHO’s ‘How is it transmitted’ page was updated on 30 April 2021 to say: “The virus can spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time. This is because aerosols remain suspended in the air or travel farther than one metre.”

The problem, according to Morawska, is that “what’s crowded and what’s poorly ventilated is very relative”.

“I’m sitting here by myself in this room, so the air is relatively fine,” she says in a Zoom call – she’s in her office looking at a carbon dioxide (CO) monitor.

“But if there were two other people – and two other people would still make it in terms of being physically distanced by 1.5 metres – ventilation would not be adequate and immediately CO would go up…

“So it is relative, and therefore putting these qualifiers – ‘crowded’ or ‘poorly ventilated’ – sends the [wrong] message.”

Something much clearer and more constructive is what’s required, she says – “Stressing that ventilation needs to be adequate to address infection transmission, that’s what’s needed.”

CO levels are the best gauge we have for measuring air quality and, thus, understanding how quickly space is being properly ventilated or not ventilated. It’s a proxy, an indicator of the relative concentration of what is emitted by humans breathing. A poorly ventilated space will have 800+ CO parts per million (ppm), while outdoor air sits around 400ppm.

As quick measures, opening windows and doors is a great, free, way to improve air quality and circulation. And to measure air quality, purchasing a CO meter, which can retail for around $200, is a great step too.

So how healthy is the indoor air of Australian buildings?

Adjunct Professor of Architecture at the University of Adelaide, Geoff Hanmer is another member of OzSAGE, where he is a built environment expert. Hanmer says we started out badly and improvement has been slow. He explains how the Infection Control Expert Group (ICEG) issued advice echoing WHO’s from the get-go, that COVID-19 was spread principally through droplets. Even so, ICEG, which advises the Australian Health Protection Principal Committee (AHPPC) and the Federal Government, didn’t start to think about airborne transmission until relatively recently. 

As a consequence, the mechanism of enforcement, recommendation and regulation has been “slow to adapt to the new information,” says Hanmer.

“When I say ‘new’, I mean information that was available in June [2020]. So when I say ‘slow’ I’m being kind, because we’ve been absolutely glacial in adapting to the new evidence that was very evident,” he continues.

Even before a global pandemic nudged us along, Australian buildings have not, as a whole, been particularly healthy. Hanmer says air quality has been “neglected”.

“We’ve basically been happy enough to have air that is comfortable and doesn’t smell, rather than air that is of good quality.”

Current National Construction Code limits governing ventilation focus on comfort and odour control. To show how long it’s been since the Code has been updated, Hanmer points to a revision “in the early 1990s that was set to reduce the impact of smoking inside, which of course doesn’t really happen anymore”.

So the actual quality of the air, and how safe and healthy it is, has been left out. “That’s something that we’re going to have to do, for a number of different reasons,” says Hanmer. And, if we invest in it, healthy air will deliver dividends far beyond reducing the spread of infectious disease. These include countless health benefits as well as reductions in absenteeism, increased productivity and more.

The race to ventilate and purify

As part of their reopening strategies, Australian state governments have introduced indoor air quality measures in public schools. These measures are particularly important given that children younger than 12 are not currently included in vaccination rollouts and targets. 

On 20 September this year, OzSAGE issued a press release urging the New South Wales Department of Education to develop a comprehensive plan for providing safe indoor air for children in its schools.

On 22 September, Victorian Premier Daniel Andrews announced 51,000 air purifiers would be rolled out to Victorian state schools. Other measures in that announcement were grants for creating outdoor learning spaces at schools and the establishment of a Ventilation Technical Advisory Panel to undertake further risk assessments of similar environments, such as early childhood settings and youth justice facilities.

Days later, the ACT Government announced it had ordered 80 carbon dioxide monitors, bringing the total number of schools in the territory monitoring CO indoors to 65.

On 28 September, a coalition of nine industry bodies, including the Facility Management Association of Australia (FMA), the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH) and the Green Building Council of Australia (GBCA), issued a joint call for Federal Government endorsed ventilation guidance – public information regarding the airborne transmission of COVID-19 and the importance of indoor air quality.

“Ventilation is front page news,” said AIRAH CEO Tony Gleeson. “People are concerned about whether they can safely return to schools, offices, gyms, public events and other spaces. 

“It’s very positive that air quality has become a topic of public conversation, but this increased awareness must be supported by solid advice. Australians need credible and practical guidance that can be easily understood by different audiences.”

Morawska echoes the sentiment, saying the need for collaboration between government departments is urgent. “This is a health threat,” she says, “but the Department of Health is not responsible for buildings… it is not responsible for schools, where we are talking about the Department of Education.

“Basically, the whole government approach needs to be there to realise that this is a threat and needs to be controlled, and the whole legislation needs to be set as such that it could happen.

“In the longer term, we need to change, modify our Australian building codes, we need to get the government, all the relevant government departments working together to address the issue,” says Morawska.

So far, these ‘ad hoc’ measures, the opening of windows, purchasing of air purifiers and monitoring CO are all she’s seen. “I often compare this to the situation where, if you are in a major storm and your roof is leaking, you do whatever prevents the house from being wet – you put a bucket underneath it. But in the longer term, you need to fix the roof.”

New normal?

The pandemic has exposed and illuminated many ongoing issues set to continue affecting society and well-being long after it has passed – insecure work, housing inequity and weak supply chains, to name a few. For each, there are questions as to whether we, in our communities, have the will to address the challenges – ‘build back better in the new normal’ – or simply continue on as before. Indoor air health in Australia is at a similar fork in the road.

For Morawska, adequate ventilation to survive the pandemic is not enough. She has hope that the air quality conversation will continue, that we’ll take steps to secure better operating buildings for the future.

We’ll need to balance our need to circulate clean, fresh air from the outside in, with our need to conserve energy and survive climate events like worsening bushfire seasons. 

Bringing in air from the outside is easy, she says, “[But] if the virus is inside and there’s polluted air outside, it’s not as simple as just bringing in air from the outside.

“As it is, our buildings are not really equipped to deal with both situations in a flexible manner and, very importantly, to minimise energy consumption.”

Natural ventilation is an affordable option, but energy used for heating in winter and cooling in summer is lost. Mechanical ventilation consumes vast quantities of energy. “We can’t just keep adding, consuming energy and burning fossil fuels,” Morawska says. Facility managers must find a balance, improving indoor air quality, preparing for threats from outside air and conserving energy all at once.

If we undertake measures now that will minimise the airborne spread of coronavirus indoors, while guaranteeing better, safer indoor air quality in the future, we may just eke a positive out of our current ordeal. 

Morawska finishes our Zoom chat with a warning. “After the pandemic is over, we will want to completely put it out of our mind. So the time to change is now.”

Photo by Trude Jonsson Stangel on Unsplash

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