Winter vs Covid - Warm air vs fresh air
07 December 2020
The ventilation dilemmaTHE LATEST:
The Association of Secondary Teachers in Ireland (ASTI) has warned that schools may be forced to close over the winter months due to ventilation and heating issues.
Ventilation is a serious issue when it comes to coronavirus. To reduce the risk of transmission, proper and adequate ventilation should be provided. During the winter months, it is not practical to keep windows and doors open as schools would not be able keep the spaces adequately heated.
Where ventilation systems are used, if they are recirculating air, these have been advised to be turned off by HSE. Only ventilation systems that provide fresh air should be used.
“if you use a centralised ventilation system that removes and circulates air to different rooms, it is recommended that you turn off recirculation and use a fresh air supply”.
It is likely that combination air conditioning that cools and heat the air use a circulation method and the fear is that any Covid-19 droplets in the air could be transmitted more easily around the room, even to those who are observing social distancing.
THE CASE STUDY:
A study in China in April linked coronavirus transmission to an air-conditioning unit after a diner at a restaurant in the city of Guangzhou infected nine others. “We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation. The key factor for infection was the direction of the airflow,” researchers from the Guangzhou Center for Disease Control and Prevention said.
Sketch showing arrangement of restaurant tables and air conditioning airflow at site of outbreak of 2019 novel coronavirus disease, Guangzhou, China, 2020. Red circles indicate seating of future case-patients; yellow-filled red circle indicates index case-patient (Guangzhou Centers for Disease Control and Prevention)
On 24 January, family "A", including a 63-year-old woman who had the coronavirus but not yet fallen ill - patient "A1" - had lunch at a Guangzhou restaurant.
Two other families, labelled “B” and “C” in the study, sat at tables next to family “A”. The families spent roughly an hour in the restaurant together. In the hours after lunch, patient “A1” went to hospital with a fever and cough. Within two weeks, nine more people – four in total from family “A”; three from family “B” and two from family “C” – had developed the coronavirus.
For ventilation systems that do circulate air, the air should be treated using air sterilising systems which kill bacteria and viruses or Hospital-Grade HEPA 13 filters which will remove virus aerosols.
For rooms where external ventilation is not a possibility, air purifying or air sterilising systems are recommended to remove airborne bacteria and viruses.
Air sterilising systems differ. Some only sterilise the air that passes through them. Some have an external effect which sterilise the air, surfaces and fabrics within the room. The latter is obviously the preferred option.
OXIZONE AIR STERILISER
Different models of the OXIZONE Air Steriliser are available for either mounting to the wall or ceiling to continuously sterilise the air internally and externally or for installation within the air conditioning system.
Air passing through is exposed to UVC light which disrupts and destroys the cell membrane of bacteria and the lipid envelope of viruses destroying them. The combination of UVC lamp, Superoxide Anion generator, Titanium Dioxide catalyst and ozone generating diode produce a transmitted effect of activated oxygen mix which continues to sterilise the air, surfaces and fabrics within the room.
These machines are specified correctly with lamp output fitted according to the room size and type with recommended fitting location for highest efficacy.
Tested by the Health Protection Agency at the Government’s Porton Down laboratories, SGS and Leeds University; the results show in excess of 99% reduction of bacteria and viruses in the air and on surfaces.
See how OXIZONE works : Youtube:
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