Good ventilation and quality air purification are key to minimising the airborne spread of COVID-19 in indoor areas including in aged care homes, experts have told a virtual forum on indoor air quality.

Experts weighed in at Rentokil Initial’s virtual event on Friday about indoor air quality and how businesses including aged care operators could provide protection against the airborne spread of COVID-19.

They include Geoff Hanmer, who is an Adjunct Professor at University of Adelaide and a member of the pandemic task force established by the International Code Council and National Environmental Health Association pandemic.

Professor Geoff Hanmer

He said the chance of catching COVID-19 indoors was  20 times that of catching the virus in an outdoor setting according to the US Center for Disease Control and Prevention.

“The difference between indoors and outdoors essentially is about ventilation… Poor ventilation in public buildings, workplace environments, schools, hospitals and aged care homes do contribute to viral spread,” Professor Hamner told the forum.

“Good ventilation is one of the best ways to reduce the risk of COVID-19 infection in concert with other mitigations including density limits, the use of PPE [personal protective equipment], and the use of air purifying devices.”

If ventilation cannot be guaranteed, then air purification is the next step, Professor Hanmer said.

University of Technology Sydney Emeritus Professor Bruce Milthorpe, who was Dean of Science at UTS for seven years, agreed and said air purifier devices needed a high efficiency particulate air (HEPA) filter to remove pathogens.

Professor Bruce Milthorpe

“HEPA filters remove very small particles down to about 300 nanometres. Although they also can remove smaller particles at lower efficiency,” Professor Milthorpe told the forum.

“The SARS-CoV-2 virus is around 100 nanometres in diameter, or about 1/500 of the diameter of a human hair,” he said. “It’s possible the HEPA filter will remove most of these viral particles from the air, but some may get through.”

Professor Hanmer said a correctly-sized air purifier was also important.

“The size of the unit, its capability of clearing the air needs to be matched to the space,” he said.

“These general principles apply both in naturally ventilated buildings, which aged care is a great example. Schools are another great example. These spaces are naturally ventilated. They don’t have mechanical systems to provide fresh air,” he said.

Also at the virtual event, Rentokil Initial and indoor air technology provider Radic8 launched air purifier VIRUSKILLER in Australia and New Zealand.

The air purifier uses a patented UV-C reactor chamber to decontaminate airborne viruses and biological pathogens.

The Rentokil Initial virtual event took place on 20 August.

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