Coved-19 and Recirculation Fans
 

Question for you current airline pilots... Are you still operating with Recirculation Fans ON? Or is your company accepting a higher fuel burn to protect the travelling public from that nasty Coronavirus?

yep still doing that , more likely to catch it from using the toilet door handle or in the airport etc....

Most aircraft put the recirc fan air through a HEPA filter. The Coronavirus is relatively large and would easily be trapped by a HEPA filter.

I'd be more worried about the person sitting next to you...

yep, that’s the advice we are getting...

What I am told is that when recircs are off, any virus could travel through a larger part of the cabin before it is vented out the outflow valves.
And with the recircs on, the cabin air is extracted more locally and while being recirculated back into the cabin, any virus would have been caught in the HEPA filters.
So it is better contained by keeping the recircs on.

So what happens to the virus in the HEPA filter; and how often is it changed and by who?

Air recirculation systems on Airbus and Boeing aircraft have HEPA (High Efficiency Particulate Air) Filters which remove dust, allergens, bacteria, viruses and other irritating particles from the air in pressurised cabins and cockpits.

All of the air in the cabin is on average completely changed every 3 minutes.

HEPA filters are very effective at removing viruses (testing shows a virus removal efficiency of 99.999%). This means that the virus will be retained in the filter.

All the information you need is on the website of Pall, a world leader in filtration:
https://shop.pall.com/us/en/aerospac...rs-zidgzyl8yrb

Specifically:
Is there a danger to maintenance personnel by removing used cabin air filters?
There is no more risk involved in replacing a cabin air filter than carrying out general maintenance on
any aircraft part that has been in service for a number of years. Maintenance staff should wear the
same personal protective equipment as for other aircraft maintenance tasks which require protection
against dust, and per the local regulations.
The used HEPA filter should be placed and sealed in a plastic bag. A specific biohazard bag is not
required for disposal of the HEPA filter in most juristictions.

Yup. Lots of good reasons to be concerned about inflight exposure. The recirc systems just don't make it to the list of credible risks.

No way (that I know of) to turn off the recirculation fans on an A320 anyway.

The bigger risk is the immigration queue, the baggage pickup, the quarantine and of course the aerobridge. No ventilation there.

The official advice seems to be to keep one metre apart from others to avoid direct transfer by infected particles in the breath. That rules out most aircraft passenger seating.

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

Possibly because air travel takes them further from home, and to countries with a perceived greater risk of infection.

Strictly speaking, the WHO and NHS UK advice is to avoid close contact with people suffering from a fever and cough. While staying a meter away from every other human being would satisfy that requirement, it's both impractical and unnecessary.

Most of the reports I've seen claim that HEPA filters will NOT stop (or catch) the Coronavirus.

Do you have sources claiming otherwise?

Every test report I’ve seen from Pall, Donaldson and independent test houses has shown that the HEPA filters used on Boeing and Airbus aircraft are extremely effective at removing viral particles in the size range of Covid-19. So I’d suggest your sources are rather questionable.

One of the theories as to why seasonal flu is seasonal has to do with indoor humidity. In the summer, indoor humidity is normally high. Expelled droplets settle to the floor or other surfaces. People touch surfaces, but luckily they don't breathe them.

In the winter, indoor humidity is generally low. Droplets tend to dry out before they reach the floor, leaving the virus itself to float in the air for a prolonged period.

Of course, it's always winter at 38,000 feet. That may make recirc fans and HEPA filtration even more important. On the other hand, increasing the frequency of air changes could lower the humidity even further, and perhaps make things worse.

Quote:
Originally Posted by dcoded View Post
Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

It also tends to take them to places where they may not have access to the same healthcare choices they have at home. And to places where the risk of being caught in quarantine are perceived as higher. Or the chances of facing quarantine upon return.

Has it crossed your mind why they are used in hospitals? The HEPA performance graphs are available with respect to viruses etc.

stop reading the National Enquirer.