That figure is taken from the paper, ‘Role of Ventilation in Controlling SARS-COV2 Transmission’ published on 30 September and available via www.is.gd/pajuji. Increasing the ventilation rate from 1 litre per second per person to 10 litres per second per person gives a reduction in relative risk between 68% and 86%, depending on the viral emission rate and the duration of exposure. This is based on models and is subject to uncertainties, points out Vent-Axia; however, it adds that the relative influence of ventilation on the removal of airborne contaminants is well understood.
Although originally it was thought the main mode of virus transmission was fomite transmission (via surfaces) it has now been confirmed that Coronavirus is also spread by aerosols that are exhaled from the nose and mouth of an infected person as they breathe, speak or cough. The majority of virus transmissions happen indoors. Being indoors, with no fresh air, the particles can remain suspended in the air for hours and build up over time. Plus, the longer people spend in the same room as these particles, the more likely they are to be infected.
As part of the campaign, a new short film released by the Government shows how coronavirus lingers in enclosed spaces, and how to keep your home ventilated. Professor Catherine Noakes, Leeds University, was an adviser for the short film and, said: “When a room does not have any fresh air, and where people are generating large amounts of aerosol through activities such as singing and loud speech, that is when transmission of coronavirus is most likely. Fresh air must come from outdoors – recirculating air just means the aerosols containing the virus move around the same room rather than being extracted outdoors. Ventilation units or any household systems that use outdoor air can be just as effective as opening windows or doors as long as they are limiting the recirculation of the same air.”
Public Health England’s guidance ‘COVID-19: epidemiology, virology and clinical features’, available via www.is.gd/ujinan, also recently acknowledged that airborne transmission can occur in ‘poorly ventilated’ spaces.
Vent-Axia has supplied ventilation to a number of COVID hospital wards and field hospitals, including the NHS Nightingale Hospital in London and the Rainbow hospitals.
Jenny Smith, head of marketing at Vent-Axia, said: “To lower the risk of COVID-19 transmission inside a home or building it is vital to increase airflow and ventilate effectively. Now is the time to check ventilation to ensure there is enough airflow to dilute the virus in the air and improve indoor air quality. Ventilating for longer and opting for ventilation with higher airflow volumes will help reduce the risk.”
The government campaign therefore advises ventilating rooms regularly either by opening windows for short, sharp bursts of 10-15 minutes throughout the day or by leaving a window slightly open continuously. This will help remove any virus particles in the air. It is also advised that kitchen or bathroom extractors are used regularly as another way to remove virus particles. It is particularly important to air a room when a household has had visitors, tradespeople, carers or someone in their support bubble visiting. It is also vital to ensure good ventilation if someone in the family has the virus to prevent it spreading to other members of the household.
Vent-Axia has launched a webpage and brochure offering essential guidance on the positive effect of ventilation in tackling COVID-19; see link below.