As scientists learn more about the role played by ventilation in the spread of COVID-19, some are starting to focus on how improving air quality can provide better protection.

Airborne transmission of small particles has increasingly been recognised as a source of coronavirus spread, prompting experts to call for a rethink of indoor ventilation.

Now, a South Australian clinical trial of ultraviolet (UV) air treatment to destroy the virus mid-air has secured $1.3 million in federal funding.

The aim is to boost protection for those most at risk — but also to make buildings and workplaces safer.

What’s being trialled?

South Australian Health and Medical Research Institute (SAHMRI) molecular microbiologist Geraint Rogers is leading a research team focusing on combatting COVID-19 outbreaks in aged care facilities.

Several coronavirus outbreaks across Australia have occurred in nursing homes, and elderly residents are among the most vulnerable.

“We’ve seen in Australia and globally that when COVID-19 outbreaks occur in these facilities they’re really catastrophic,” Professor Rogers said.

“Transmission occurs very quickly and the mortality rates are very, very high.

“We want to see if we can find ways to more effectively protect people in aged care.”

Professor Geraint Rogers is a molecular microbiologist and microbial ecologist.(Flinders University)

Professor Rogers said that, until now, control efforts have mostly focused on social distancing, hand hygiene and wearing personal protective equipment (PPE).

His trial will involve installing UV light devices inside air-conditioning units across several aged care facilities, and checking whether they reduce rates of infection.

“Each facility has different characteristics — the building is different, the air-conditioning systems are different and so on,” Professor Rogers said.

“The more context we can test this in, the more confidence we can have in the results we’re getting.”

How could UV light help?

Devices known as UV air sterilisers are commercially available in Australia, and Professor Rogers said the upcoming trial will use “existing technology” which has already proven effective in killing the bacteria which causes tuberculosis.

Protection against coronavirus has largely focused on hygiene, not UV light.(AP: Andy Wong)

“It’s relatively inexpensive, it can be retrofitted into existing facilities, and it doesn’t require any change in activities or the lifestyle of the people who are there,” he said.

“What we’re trying to do is to see whether a technology which has been shown to be effective in other contexts to kill pathogens might be able to prevent the viral particles from staying viable and being potentially infective within the air.

“There’s a couple of different ways that it can be done. One is to [install the devices] within the ducts themselves, so as the air passes through the ducting it’s exposed to the UV.

University of Melbourne environmental scientist Robyn Schofield explained that UV light had the potential to act as a “disinfectant” by breaking down viral and bacterial DNA.

“There has been extensive work both in the US and in Europe on upper-room UV disinfection,” she said.

“It’s great that there is funding going towards understanding whether it’s appropriate in our healthcare settings.”

Is safety a factor?

Exposure to UV radiation has long been recognised as a cause of skin cancer.

“UV light, whether it’s from the sun or [created] artificially, does damage our skin … it’s DNA-damaging,” Dr Schofield said.

Dr Robyn Schofield said there were risks as well as potential rewards.(Supplied: University of Melbourne)

She said she had some “reservations”, including around whether the technology would create “radicals” — unstable atoms that could damage cells.

But she said the trial had potential to be effective and helpful, provided there were safeguards.

“I do think we need to not just consider the safety concerns of skin, but also consider the safety concerns of the air quality that’s being returned from the use of the technology,” she said.

“Understanding those safety concerns, which a clinical trial would do — [it’s] really a worthy thing to do,” she said.

Professor Rogers said the trial would take the necessary precautions to ensure aged care residents were not put at risk.

“UV damages nucleic acids, RNA and DNA, and that’s why we use it to kill viruses. In Australia, we know it can damage ourselves as well, that’s why we get sunburn,” he said.

“As far as we’re concerned, there’s no risk to anyone in the facility at all.”

When will it start?

While the planning and approvals stages are still ongoing, Professor Rogers said he hoped to begin the trial during the upcoming flu season.

But he said it could take at least another year for the work to be repeated, so the results could be analysed and conclusions drawn.

“We will look at rates of infection and levels of viral particles in the air and on surfaces when we’ve got the units running, and when we’ve got the units turned off.

“We’ll be able to compare between the two situations.”