Experts says clean air is more important than clean hands

At the outset of the pandemic, it was drummed into us to social distance and wash our hands thoroughly. We were obsessed with not touching things which could be infectious or avoiding touching our face after we touched things.

But ventilation expert Orla Hegarty insists the coronavirus is primarily spread by air.

She's an Assistant Professor at the School of Architecture, Planning and Environmental Policy at the University of Dublin who has been advising institutions, especially schools, on measures they can take to reduce the transmission of the coronavirus.

'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.'

Hegarty says air quality of buildings can be measured, managed, and monitored, and improving ventilation 'reduces or eliminates' virus risks.

Her certitude is bracing after it took many health authorities, including the World Health Organisation, so long to acknowledge the reality of aerosol transmission. There was no shortage of clues: In one high-profile example early in the crisis, one singer at a choir practice in Washington, DC infected 52 of 61 others, two of whom died.

Ms Hegarty says 'active and targeted prevention of specific high-risk conditions', in places like schools can keep buildings open and people out of hospital.

'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.

Atmospheric Chemist Professor Kimberly Prather from the University of California told 774 ABC radio, 'this virus is airborne and you get infected by inhaling shared air indoors'.

She says people in positions of power have not taken airborne transmission seriously and that is costing us dearly.

'Any time you're indoors, you're going to breathe (another person's) breath…' she said.

And that other person doesn't need to be coughing or sneezing to transmit the virus.

Dr Zeynep Tufekci, writing for The New York Times, also drives the aerosol transmission message.

'The vast majority of transmission has been indoors, sometimes beyond a range of three or even six feet,' she wrote, amazed that officials didn't revise their information about transmission until May 2021.

'The super-spreading events that play a major role in driving the pandemic occur overwhelmingly, if not exclusively, indoors.'

Ms Hegarty says COVID rules which ignore the reality of airborne viral transmission result in 'unknowing high-risk behaviour on the one hand, and unnecessary social isolation and business closures on the other'.

Infections fall when weather is warmer, and people are outside more. In cold conditions indoors the airborne virus can infect people who are as far as 8 metres apart. In cool, dry air worksites like meatpacking plants the virus spreads rapidly.

A New York Times interactive graphically visualises the spread of airborne transmission in a classroom.

So, what can schools do to reduce their COVID risk?

The risk of contracting COVID-19 at school can be mitigated by good ventilation and air management and wearing properly fitted masks. 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: Wearing properly fitted masks; moving outside when possible; regular 'airing out' of rooms; spreading out into safer rooms; avoiding crowds; taking more breaks; re-setting ventilation systems; checking wall vents are not blocked; and opening windows. Limiting activities such as shouting, singing, and exercising indoors is also advised.

But when it gets too cold to be outside or have windows open, there's gadgets.

We can increase humidity with humidifiers. Carbon monoxide monitors can measure 'stale air' to signal unsafe conditions. Portable fans can be helpful to improve airflow. HEPA air purifiers may greatly improve air quality.

Partly because of Ms Hegarty's advocacy, the Irish Department of Education is providing poorly ventilated schools with air monitors and air cleaners.

Irish schools are now advised to have doors and windows open to increase natural ventilation, to set air conditioning systems to 100 per cent fresh air and to use carbon dioxide (CO2) monitors and, where needed, air cleaners.

Teachers' unions were critical of what they described as 'a lack of attention paid to indoor aerosol transmission in often cramped and over-crowded classrooms'.

The Irish National Teachers’ Organisation said it welcomed the changes, while the Teachers’ Union of Ireland said it highlighted the unsuitability of many school buildings for teaching and learning.

Ms 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.'

Ms Hegarty cited Australia's quarantine hotels as an example of how the design of a space makes it vulnerable to viral transmissions. The poorly ventilated internal corridors meant people were being infected between different rooms across the corridor.

She says most ventilation issues in public buildings are solvable if the risk of airborne transmission is acknowledged, and 'many can be mitigated quickly, often at no cost'.