Covid: Ventilation just as important as hand-washing, schools told

Written by: Pete Henshaw | Published:
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Improving air quality and ventilation in classroom spaces should be as important as social distancing, mask-wearing and hand-washing, doctors have told schools.

In this regard, schools could learn some lessons from how the aviation industry have been working to make planes Covid-safe.

The argument is put forward in a commentary published in the Journal of the Royal Society of Medicine by doctors from Imperial College London and Louise Voden, headteacher of Nower Hill High School in Middlesex (Asanati, Voden & Majeed, 2021).

The authors call for specific guidelines to support schools in better using effective ventilation to reduce the risk of Covid-19 transmission in the classroom.

The commentary also calls for teachers to be added to the priority list for vaccinations and suggests the introduction of temperature “kiosks” at the school gate to ensure any students with a fever are sent home directly.

The commentary points out that it takes about four minutes for the number of small droplets in the air to be halved in a room with no ventilation, whereas with mechanical ventilation turned on in a room, the number of respiratory particles is halved in 1.4 minutes.

The commentary adds: “In a room that also has a door and window open, the number is halved after 30 seconds – substantially faster than in poorly ventilated and unventilated rooms.”

It continues: “Therefore, an important approach to lowering the concentrations of indoor air pollutants or contaminants, including any viruses that may be in the air, is to increase ventilation. Increasing air flow by ventilation, whether by window and door opening or mechanical systems – which could mix outdoor air with indoor air – or air filtration and cleaning devices, reduces the risk of infection by diluting concentrations of respiratory particles and removing them in the ambient air.

“Improving indoor air quality in classroom spaces should be followed at the same level as government advice regarding social distancing, mask-wearing and hand-washing to lower the risk.”

Lead author Dr Kaveh Asanati, honorary clinical senior lecturer in occupational lung disease at the National Heart and Lung Institute at Imperial College London, said: “To keep schools open, there is an urgent need to implement more effective on-site mitigation strategies, with particular attention to ventilation and testing. In addition, it is essential that teachers and other school staff should be added to the priority list for vaccination.”

One potential solution, the commentary suggests, is the used of high-efficiency particulate air (HEPA) filters, which have been used effectively by the aviation industry.

Dr Asanati added: “The multi-layer risk reduction strategy used in the aviation industry seems to have been working efficiently. The strategy includes testing passengers, the use of face coverings or masks, hygiene measures and, more importantly, maintaining clean air by circulating a mix of fresh air and recycled air through HEPA filters.”

While few school buildings have HEPA filtration, the authors say that one practical option would be the use of portable HEPA filtration units. They would like to see a feasibility study undertaken of implementing better ventilation and filtration systems in schools, as well as pilots and research involving indoor air quality and heating, ventilation and air conditioning experts.

Until then, they said, keeping doors and windows open – for as much as is reasonably practicable – seems to be the best way forward.

  • Asanati, Voden & Majeed: Healthier schools during Covid-19 pandemic: Ventilation, testing and vaccination, Journal of the Royal Society of Medicine, February 2021:


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