The coronavirus is primarily spread through the air and sometimes there is no “safe distance”, according to ventilation expert Orla Hegarty.
“It is now believed … that most spread is airborne, that there is no safe distance in a poorly ventilated room and that conditions can move from low to high risk within 15 minutes,” she told The Irish Times.
“COVID-19 is a respiratory virus; it is caught from breathing. In the open air, the virus is diluted and dispersed in the air, but inside aerosols – the particles small enough to remain in the air – can linger, spread and build up to dangerous levels, similar to cigarette smoke.
“Ventilation is key to prevention because the risk of breathing in COVID-19 is 20 times higher indoors.”
Assistant Professor Hegarty, from Dublin University’s school of architecture, planning and environmental policy, has been advising institutions, including schools, on how to reduce the transmission of the coronavirus.
“In buildings and vehicles, (viral particles) can build up, fill a space, linger for hours and infect many people. Viral particles in the air behave like smoke and must be cleared out,” she said.
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Australia’s Professor Raina McIntyre is calling for official recognition of the role of aerosol viral spread.
“Such recognition would have widespread implications for how healthcare workers are protected, how hotel quarantine is managed, not to mention public health advice more broadly,” she wrote for The Conversation.
“A false narrative dominated public discussion for over a year. This resulted in hygiene theatre – scrubbing of hands and surfaces for little gain – while the pandemic wreaked mass destruction on the world.
“But handwashing did not mitigate the most catastrophic pandemic of our lifetime. And the airborne deniers have continually shifted the goalposts of the burden of proof of airborne spread as the evidence has accrued.”
An article submitted by three senior doctors to the Australian Medical Journal in April said there is “clear and compelling evidence for airborne transmission”, blaming our refusal to accept this for breaches in hotel quarantine and thousands of COVID-19 cases among healthcare workers.
In the article, headlined ‘Australia must act to prevent airborne transmission of SARS-CoV-2’, Drs Zoe Hyde, David Berger and Andrew Miller wrote: “Countries which acknowledged the danger of airborne transmission have not only been able to control COVID-19 in the community, but where cases have occurred, they have been able to safeguard healthcare workers from getting infected.
“Countries which have not, including Australia, the United Kingdom, the United States and many European nations, have not only seen widespread community transmission, but staggering numbers of healthcare worker infections.
“It has seemed at times as if any reason, other than airborne transmission, is being sought to explain occupationally acquired healthcare worker infections.”
The doctors said the evidence was sufficiently strong to warrant the immediate strengthening of Australia’s infection prevention and control guidelines.
“We must apply the precautionary principle and urgently improve biosecurity measures at ports, airports and quarantine facilities, lest outbreaks continue to spill over into the community.”
So, why is it so important to accept that the coronavirus is spread in the air?
“Accepting how SARS-CoV-2 spreads means we can better prevent transmission and protect people, using the right types of masks and better ventilation,” says Prof. McIntyre.
“Think about it. Airborne deniers tell us infection occurs after a ballistic strike by a single large droplet hitting the eye nose, or mouth. The statistical probability of this is much lower than simply breathing in accumulated, contaminated air.
“In hotel quarantine, denial of airborne transmission stops us from fixing repeated breaches, which are likely due to airborne transmission.
“We need to select quarantine venues based on adequacy of ventilation, test ventilation and mitigate areas of poor ventilation. Opening a window, drawing in fresh air or using air purifiers dramatically reduce virus in the air.”
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The expert advice is that super-spread events – where five people or more are infected – can be prevented, because 97 per cent of them happen indoors.
Many measures are simple and cheap: regular ‘airing out’ of rooms; resetting ventilation systems; checking wall vents are not blocked, and opening windows. Limiting activities such as shouting, singing and exercising indoors is also advised as is increasing humidity with humidifiers as the virus thrives on dry air.
Asst. Prof. Hegarty says vaccines alone will not end the pandemic.
“We now understand that risk of transmission is predominantly indoors and very specific to certain buildings and indoor air conditions.
“These conditions are preventable, and this knowledge is key to stopping infections and to opening buildings at low risk.”
Were you aware of the extent of airborne transmission of coronavirus? What should we do differently to stop airborne transmission? Have your say in the comments section below.
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