Confusion over Covid-19 ventilation guidelines in schools and congregated settings

Airflow is about more than opening windows, UCC expert says
Confusion over Covid-19 ventilation guidelines in schools and congregated settings

The National Public Health Emergency Team (Nphet) will discuss air-flow guidelines in its meeting on Thursday. Picture: Larry Cummins

Confusion around ventilation guidelines to tackle Covid-19 in schools and congregated settings must be addressed, a Cork expert has said.

The National Public Health Emergency Team (Nphet) will discuss air-flow guidelines on Thursday as part of its overall recommendations for living with Covid-19 in the months ahead. 

It follows apparent confusion between health authorities at a HSE webinar for teachers, which heard that measures used in schools until now would remain unchanged despite growing evidence the UK variant is more transmissible.

Just hours later, deputy chief medical officer Dr Ronan Glynn told the Irish Examiner that updated guidelines on ventilation prepared by the Health Protection Surveillance Centre will be discussed at a Nphet tomorrow.

Nphet has not given explicit guidance around ventilation in the way masks or touching surfaces has been addressed.

Specific air-flow guidelines for schools and workplaces, including meat factories, should have been part of the Irish response, but it is not too late to implement this now, according to Professor of Physical Chemistry at UCC, John Wenger.

Prof Wenger, who was one of 239 international scientists who wrote to the World Health Organization on this last year, said airflow is about more than opening windows.

“I really hope there will be clear guidelines, and strong public messaging from the Government on this now," he said.

We need to emphasise that the virus travels through the air.

Car-pooling can be a source of infection, but he said potential levels of the virus can be diluted by opening the windows, as well as wearing masks.

Retail staff could open windows or doors while they are on breaks, which allows air to escape and again dilutes any virus in the air even if windows are closed some of the time to keep warm.

This is not a new idea as countries including Spain and Japan promote better ventilation as part of their national strategy, Prof Wenger said.

“Accepting the importance of aerosol transmission in the spread of SARS-CoV-2 would provide the HSE with a scientific basis for new measures to specifically protect against airborne spread of the virus,” he said.

Advice around ventilation would empower people to fight the virus, Assistant Professor at the School Of Architecture University College Dublin Orla Hegarty said.

“I think it is very positive Nphet will take action on building ventilation — this can give us a road-map for re-opening carefully and scientifically rather than a blanket lockdown,” she said.

The risk of transmission in everyday indoor situations can be decreased by creating a flow of air.

The risk of catching Covid is 20 times higher indoors than outdoors.

"Outdoors is like the sea — the virus is diluted. Indoors is like a fishbowl: The virus in the air is trapped and more concentrated,” she said.

In Japan, the strategy includes advice around avoiding the three Cs — crowded places, close contacts, and closed spaces. 

While not perfect, analysts say this has helped to contain their mortality level with 4,300 people dying in a country with a population 26 times that of Ireland.

Prof Hegarty said: “Policies set out in March were based on what we understood then. In the meantime, international science has moved on but that has not been translated into public health advice here.” 

She said indoor ventilation patterns are carefully designed and can be adjusted by engineers or architects when measured and found wanting. This could be done for nursing homes and direct provision centres as well as schools.

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