Posted by Michael Gilligan on 16/10/2020 21:08:50:
Posted by blowlamp on 16/10/2020 17:37:37:
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It seems to me to say that their filter captures particulates that might be carrying pathogens/viruses.
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I agree, Martin
… and then eliminates 99.99% of what exactly ?
strangely, although there is an asterisk following 99.99% there is no explanatory footnote
MichaelG.
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Look at this link Michael, it will help you better understand the percentage figures manufacturers quote: LINK
The following is an OPERATORS INFORMATION TRANSMISSION from Airbus regarding ATA 21 – Virus Outbreaks – Novel Corona Virus (2019-nCov)
Quoting:
"Based on available information and Airbus’ understanding, Airbus do not expect that any special precautions or operational procedures are necessary, for example, to operate with the cabin air recirculation fans switched off, because:
1. The efficiency of HEPA filters is at least 99.97 per cent at 0.3 micron (Dop Test, MIL STD 282). The efficiency increases with bigger particles and also with smaller particles. This characteristic, whereby efficiency increases with smaller as well as bigger particles is achieved by the use of multiple capture mechanisms and the filters are similar to those used in hospital applications. Therefore the efficiency of the HEPA cabin air recirculation filters is greater than the above statement for particles within the size range encompassed by a typical virus (0.01 to 0.2 microns).
2. The airflow induced by the cabin recirculation fans is designed to assist in maintaining the correct cabin airflow pattern. The cabin conditioning air enters at the top of the cabin and leaves at floor level and is designed to prevent longitudinal airflow within the cabin. Importantly, the toilets and galley are areas where air is extracted and directed overboard without re-entering the cabin areas (it is not recirculated).
3. The recirculated air flow is a significant part of the total airflow which flows over the passengers and removes locally generated contaminants downward where it exits the passenger compartment at floor level local to the source of the contaminant. The cabin air exchange rate is approximately once every 3 minutes for outside air, but this figure improves to once every 2 minutes with the use of recirculated air."
Concluding, I would not be much concerned about the air inside the cabin. My concern would be that every one is wearing their masks properly and act in a way so as to protect oneself and the others. I definitely take all precautions and avoid touching surfaces as much as possible. Not eat anything onboard unless it's really necessary etc.