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  • The early days of the coronavirus pandemic were a confusing time.  

  • There was a lot of conflicting information flying around

  • and it was hard to know what to believe about how the virus behaved and the best practices to stay safe.

  • Since then, things have stabilized somewhat and the official advice from public health organizations hasn't changed much:

  • wash your hands, avoid crowded indoor spaces, wear a mask, and practice social distancing.

  • A lot of these precautions are based on the belief that the virus isn't airborne,

  • but some researchers are now challenging this notion.

  • So, what is at the heart of this debate, and how does it affect you?

  • Airborne can be something of a confusing label.

  • Right now, it's widely accepted that the virus is carried by the droplets that we expel when we talk or cough.

  • These droplets do travel through the air, but aren't consideredairbornebecause they typically fall out of the air immediately

  • and land within about two meters.

  • Hence the recommended social distancing guidelines.

  • But smaller than droplets are aerosolstiny particles that, as a rule of thumb, are under 5 microns in size.

  • For reference, that's smaller than a single red blood cell, which are typically about 6 to 8 microns in diameter.

  • These tiny specks can be suspended in air for much longer by air currents, so aerosols are airborne.

  • Since the 1930's, the consensus was that aerosols were not a major transmitter of respiratory viruses like influenza.

  • When the novel coronavirus emerged it was categorized as a respiratory virus too,

  • but oddly its symptoms are so varied it behaves in some ways like a vascular disease,

  • and scientists still aren't clear exactly how this new virus operates.

  • If the virus was really just carried by droplets, there are some instances of infection that some scientists say shouldn't have been possible.

  • Proponents of the aerosol transmission possibility point to a choir practice in Washington state

  • that led to 33 members of a 61 person group to contract the virus.

  • They claim it supports their notion that aerosols, poor ventilation, and long exposure time were to blame.

  • Other investigators couldn't rule out droplets or infected surfaces as culprits, though.

  • You may be wondering why the World Health Organization won't say definitively if the virus is airborne or not.

  • They maintain there's just not enough proof yet.

  • One problem is that devices that sample for aerosols can damage a virus's protective lipid envelope,

  • resulting in an undercount of how many viral particles are actually present in the sample.

  • We don't know how long the virus can stay suspended in air and remain infectious,

  • though one study reports that can be as long as 16 hours.

  • We also don't know how much of a viral load is needed to cause infection.

  • If it turns out a relatively small number of viruses are dangerous, then aerosols would represent more of a threat.

  • Still, there's enough concern that almost 240 clinicians, infectious-disease physicians, epidemiologists, engineers, and aerosol scientists

  • published an open letter to the World Health Organization pushing them to reconsider their position

  • and their advice on how to combat transmission.

  • The authors argue the WHO's standard of proof is too high,

  • even though they claim more evidence exists of airborne transmission than passing through droplets or surfaces.

  • The WHO has since changed their stance somewhat and now says it's possible that the coronavirus is carried through aerosols,

  • but they're not recommending precautions like improving ventilation or using upper-room UV light to kill it.

  • Part of the reason they haven't pushed for additional precautions is because they have to consider the cost of following their guidelines.

  • If countries with scarce resources implement measures that are ultimately meaningless, it can keep them from focusing their efforts on effective precautions.

  • Then again, if the virus is really transmitted by aerosols, then insufficient measures can cost lives too.

  • It's not an enviable position to be in.

  • But what does this all mean for you, specifically? What should you change?

  • Well, if you've been wearing a mask and avoiding spending long periods of time inside crowded and poorly ventilated buildings, you're already on the right track.

  • These are already the guidelines the WHO recommends.

  • Even cloth masks can help break the chains of transmission.

  • Less so if the virus is carried by aerosols, but a well fitted mask that covers the nose and mouth can still help.

  • Aerosols can build up indoors and the more people there are, the more likely that someone is shedding the virus.

  • So again, don't linger inside around people if you can avoid it.

  • Researchers are still debating whether or not the virus is airborne but it shouldn't really change the game plan for most of us.

  • Continue to do your part and look out for yourself and others and we can get through this.

  • As events unfold, we have kept up with the scientific understanding of the novel coronavirus.

  • If you want to know more about this topic check out our coronavirus playlist here.

  • Make sure to subscribe to Seeker for more COVID-related news and I'll see you next time on Seeker.

  • Thanks for watching, and stay safe.

The early days of the coronavirus pandemic were a confusing time.  

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B2 airborne transmission carried aerosol health organization air

Is the Coronavirus ‘Airborne’ or Not?

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    Summer posted on 2020/10/08
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