Japan supercomputer shows humidity affects aerosol spread of coronavirus

[snoop1130]

Japan supercomputer shows humidity affects aerosol spread of coronavirus

By Rocky Swift

 

FILE PHOTO: computer image created by Nexu Science Communication together with Trinity College in Dublin, shows a model structurally representative of a betacoronavirus which is the type of virus linked to COVID-19, better known as the coronavirus linked to the Wuhan outbreak, shared with Reuters on February 18, 2020. NEXU Science Communication/via REUTERS

 

TOKYO (Reuters) - A Japanese supercomputer showed that humidity can have a large effect on the dispersion of virus particles, pointing to heightened coronavirus contagion risks in dry, indoor conditions during the winter months.

 

The finding suggests that the use of humidifiers may help limit infections during times when window ventilation is not possible, according to a study released on Tuesday by research giant Riken and Kobe University.

 

The researchers used the Fugaku supercomputer to model the emission and flow of virus-like particles from infected people in a variety of indoor environments.

 

Air humidity of lower than 30% resulted in more than double the amount of aerosolised particles compared to levels of 60% or higher, the simulations showed.

 

The study also indicated that clear face shields are not as effective as masks in preventing the spread of aerosols. Other findings showed that diners are more at risk from people to their side compared to across the table, and the number of singers in choruses should be limited and spaced out.

 

There has been a growing consensus among health experts that the COVID-19 virus can be spread through the air. The U.S. Centers for Disease Control and Prevention (CDC) revised its guidance this month to say the pathogen can linger in the air for hours.

 

The Riken research team led by Makoto Tsubokura has previously used the Fugaku supercomputer to model contagion conditions in trains, work spaces, and class rooms.

 

Notably, the simulations showed that opening windows on commuter trains can increase the ventilation by two to three times, lowering the concentration of ambient microbes.

 

"People's blind fear or unfounded confidence against the infection of COVID-19 is simply because it is invisible," Tsubokura said.

 

-- © Copyright Reuters 2020-10-14

 

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[Jack Mountain]

Computers says no .... Clever, no worries for being wrong, computer did it.

[ukrules]

Interesting when you consider how humid it is in this region.

[DrTuner]

I guess Flying Saucage was right, he mentioned this a few times before.

 

If you've ever breathed out in dead calm conditions at -20 DegC (the air is bone dry then) , then you know how long the particles can float in the air. Minutes.

Edited October 14, 2020 by DrTuner

[Flying Saucage]

59 minutes ago, DrTuner said:

I guess Flying Saucage was right, he mentioned this a few times before.

 

If you've ever breathed out in dead calm conditions at -20 DegC (the air is bone dry then) , then you know how long the particles can float in the air. Minutes.

Thanks DrTuner for remembering this!

 

One important point is to not only rely on the ideas of virologists and medics regarding the transmission of the virus. There are also physical aspects in the transmission of the virus, which are not so obvious for them on the first view. Virologists and medics are specialists in other fields than physicists and engineers.

 

My theory is a little different to the OP, though. My idea is that the air drying effect of any AC helps. This seems to be a contradiction to the OP, however this is not the case.

 

Mind that the contaminated aerosols are exhaled water droplets. Any air condition dries the air, and hence condensates the aerosols, and by this removes them from the ambient air. This condensation works even more effective when the air is dry already. Or, in other words, without AC, the situation stays more critical. This then is a link to the OP, to counter the perceived contradiction of my idea to the OP.

 

From the perspective of physics, this effect is absolutely obvious. However, I haven't seen any study about this yet.

 

One thing from the OP is absolutely clear as well: At higher temperatures, the water droplets evaporate, and also the air is able to contain a higher percentage of vapor (evaporated water) than at cold temperatures. And when a contaminated droplet evaporates, the virus will likely die, as it needs water to survive. At colder temperatures the droplet will not evaporate. It stays in the air much longer.

 

This is the case with fog. Fog are water droplets, the water is not evaporated. It's clear that these conditions and this mechanism help the virus to survive. Indoors, you don't see the droplets as you do outdoor, because the concentration is lower than in the fog outdoors. But, the droplets are there, and stay there longer than at higher temperatures. And again, the use of an AC would help to reduce the concentration of the aerosols, also at lower temperatures.

 

Edited October 14, 2020 by Flying Saucage

[onebir]

If humidity slows down the virus' spread, it must spread pretty damn well, judging from what happened during the extremely humid Israeli summer.

[Estrada]

The Japanese Supercomputer got it wrong. As we say "garbage in garbage out". ASHRAE research has been done years ago and is part of air-conditioning systems design considerations. The fact is that transmission efficiency of the virus at 30C and 35%+ relative humidity, is close to zero. However, at 20C and 35% RH the transmission efficiency is 100%.  If the RH is increased to 50% the transmission efficiency is reduced to 15%. The problem that the Supercomputer got wrong, is that if the % humidity is increased to 65%, the transmission efficiency is increased to 85%. If the humidity is increased further to 80% the transmission rate is close to zero yet again. In cold climates, if the temperature falls to 5C, the transmission rate at all RH's is not reduced below 45%. This is why the Corona viruses are most transmissible in cold winter climates.

[BritManToo]

12 hours ago, ukrules said:

Interesting when you consider how humid it is in this region.

72% in my living room right this minute (30c).

Sometimes it can get as low as 55% in the late afternoon.

About the same for the last 5 months.

Edited October 15, 2020 by BritManToo

[DrTuner]

4 hours ago, car720 said:

Not doubting what you say is correct however I cannot help noticing that Europe and the UK (cooler) have high rates of covid, as well as the southern states of Australia, yet the northern states have very very litte.

Large swathes of land, in Lapland it's getting frosty while Sicily is still pleasant. Same effect is in play accross the different climates in the US.

[Flying Saucage]

7 hours ago, Estrada said:

The Japanese Supercomputer got it wrong. As we say "garbage in garbage out". ASHRAE research has been done years ago and is part of air-conditioning systems design considerations. The fact is that transmission efficiency of the virus at 30C and 35%+ relative humidity, is close to zero. However, at 20C and 35% RH the transmission efficiency is 100%.  If the RH is increased to 50% the transmission efficiency is reduced to 15%. The problem that the Supercomputer got wrong, is that if the % humidity is increased to 65%, the transmission efficiency is increased to 85%. If the humidity is increased further to 80% the transmission rate is close to zero yet again. In cold climates, if the temperature falls to 5C, the transmission rate at all RH's is not reduced below 45%. This is why the Corona viruses are most transmissible in cold winter climates.

Interesting! If this is part of air-conditioning design considerations, it indeed confirms a positive effect of AC on the transmission of the virus, as I believe it is the case.

 

This also shows that the whole issue is way more complex, however. Difficult to understand the mechanism which causes the transmission efficiency to go up and down so strongly, as e.g. at T=20C, when the humidity goes up from 35%, to 50%, 65% and 80%. Do you have any explanation what happens to the virus/aerosols/dynamics-of-transmission at these different conditions?

 

In any case, still it is obvious that an AC helps to remove/reduce aerosols and therefore the virus concentration in the ambient air.

 

Is there any link available for the ASHRAE study you mentioned?

 

Regarding the Supercomputer and "garbage in garbage out", I understand your point. It's not the computer which possibly got it wrong, it's the data and program the users apply which might describe the reality not optimally.

 

Edited October 15, 2020 by Flying Saucage

[DrTuner]

This also sort of implies the measures, such as social distancing, masks, etc should adapt to the surrounding environment. If the transmissibility is near 0% due to the environment, the health risks of using masks (bacterial contamination of the cloth due to moisture and not cleaning them, f.ex.) are not worth it and social distancing can be reduced. On the other hand, winter is coming, wear masks and keep away from people. 

 

But I've yet to see any place adapting real-time to the environment. Weather sensors on smartphones could be a good idea.

Edited October 15, 2020 by DrTuner

[natway09]

The virus cannot move on it's own.

It needs a medium to transport it 

[teacherclaire]

The researchers used the Fugaku supercomputer to model the emission and flow of virus-like particles from infected people in a variety of indoor environments.

 

Amazing what all these former Panty Vending machines are able to do. 

[rabas]

3 hours ago, Flying Saucage said:

This also shows that the whole issue is way more complex, however. Difficult to understand the mechanism which causes the transmission efficiency to go up and down so strongly, as e.g. at T=20C, when the humidity goes up from 35%, to 50%, 65% and 80%. Do you have any explanation what happens to the virus/aerosols/dynamics-of-transmission at these different conditions?

I fully agree the real physics problem is very complex and several other studies have shown different outcomes.

 

Below is the video. I think they are simply measuring particle travel versus size, humidity, turbulence, and gravity, etc. If so, the only way to account for humidity decreasing dispersion (travel distance) would be via the evaporation rate of particles, i.e, shrinking slower in humid air. The heavier the particle the faster it falls out of the air and thus the shorter distance it travels.

 

Of course, they may not be accounting for the 100 miles/hour wet sneezes reported elsewhere.

 

VIDEO:  https://www.youtube.com/watch?v=rv8VX-Sk_hs

 

The Reuters Article

 

Edited October 15, 2020 by rabas

[DrTuner]

5 minutes ago, rabas said:

VIDEO:  https://www.youtube.com/watch?v=rv8VX-Sk_hs

That looks fairly disgusting. Like Thai politicians spewing BS.

 

Edited October 15, 2020 by DrTuner

[Percy P]

On 10/14/2020 at 10:05 PM, DrTuner said:

I guess Flying Saucage was right, he mentioned this a few times before.

 

If you've ever breathed out in dead calm conditions at -20 DegC (the air is bone dry then) , then you know how long the particles can float in the air. Minutes.

Correct and people who go around without a mask covering  nose and mouth do so at their own risk.

[ukrules]

On 10/14/2020 at 10:49 PM, Flying Saucage said:

One thing from the OP is absolutely clear as well: At higher temperatures, the water droplets evaporate, and also the air is able to contain a higher percentage of vapor (evaporated water) than at cold temperatures.

Yes, I suspect it's a combination of humidity and temperature.

 

For example, do you know just how humid it is in Wuhan?

 

Wuhan :

 

Bangkok :

 

Not much difference, eh. Of course the temperature is very different.

 

Perhaps 'absolute humidity' plays a part.

 

So I think we're looking at humidity plus temperature.

 

[DrTuner]

5 hours ago, Percy P said:

Correct and people who go around without a mask covering  nose and mouth do so at their own risk.

Although I doubt the paper masks that have one inch gaps next to the nose help that much when inhaling, you'll need a properly fitting one. Stops sneezes, sure. 

Edited October 16, 2020 by DrTuner

[DrTuner]

Obviously there's the dew point too, in some conditions droplets become rain and fall down.

 

https://en.wikipedia.org/wiki/Dew_point

 

By now there should be plenty of studies of superspreader events, should not be too hard to estimate the envirinmental conditions where they happened and see if there is a correlation. 

[Flying Saucage]

7 minutes ago, ukrules said:

Yes, I suspect it's a combination of humidity and temperature.

 

For example, do you know just how humid it is in Wuhan?

 

Wuhan :

 

Bangkok :

 

Not much difference, eh. Of course the temperature is very different.

 

Perhaps 'absolute humidity' plays a part.

 

So I think we're looking at humidity plus temperature.

 

I strongly believe that the influence of the temperature is much bigger than the influence of humidity. Liquid water rather than vapor helps the virus to survive longer, and hence helps the virus to remain contagious longer. The water droplets of contaminated aerosols last longer when the temperature is lower.

 

Besides of this, reducing or removing aerosols from the ambient air, be it by ventilation, air purification or air conditioning, is the way to avoid infections or at least to turn potentially risky infections to mild or asymptomatic infections. 

 

Asymptomatic infections can be seen as something positive, as they create personal immunity and boost herd immunity. 

 

Again, it's not rocket science. But many people and most governments don't want to see or don't want to accept especially my last point above.

[ukrules]

2 minutes ago, Flying Saucage said:

 

Again, it's not rocket science. But many people and most governments don't want to see or don't want to accept especially my last point above.

Agreed, I've also been reading about the effects of evaporation on virions while they're airborne.

 

Something mentioned salt concentrations and evaporation affecting the viability of the virions.

 

An interesting read where they look into this for influenza : https://jvi.asm.org/content/88/14/7692

 

The relationship seems to be quite complex, googling 'absolute humidity virus spread' shows me plenty of information that's new to me.

 

[Flying Saucage]

59 minutes ago, ukrules said:

Agreed, I've also been reading about the effects of evaporation on virions while they're airborne.

 

Something mentioned salt concentrations and evaporation affecting the viability of the virions.

 

An interesting read where they look into this for influenza : https://jvi.asm.org/content/88/14/7692

 

The relationship seems to be quite complex, googling 'absolute humidity virus spread' shows me plenty of information that's new to me.

 

Very good article, which really points out the complexity of the transmission very well. Thanks for the link! 

 

Despite the complexity of the issue and the numerous open questions about the mechanisms itself, it explains quite well the effects of temperature, RH and AH, and by this the reasons why northern countries, like Europe or the US, are more vulnarable to a flu epidemic than tropical countries. It surely is feasible to extend these insights to the Corona virus as well.

 

One thing is backed again also by this study: It is a combination of climatic conditions like temperature, humidity, UV-radiation on the one hand, which makes the virus less transmittible in Thailand as a tropical country, compared to other countries with cold winters, combined on the other hand with a slightly higher grade of social distancing compared to countries like India or Indonesia and their dense population.

 

The article described very well the transmission efficiency of the virus. However, as this was not the topic of the article, it did not consider the humans reaction to high temperatures, like the positive effects of opening windows or the use of air condition, and the impact of these reactions to the transmission of the virus. This together with the reduced transmission efficiency makes Thailand a quite safe country.

 

Combining everything, a viable conclusion in my opinion is that indeed Thailand, due to its geographic location (and not to race as many Thais seem to believe in their xenophobic mindset), is quite lucky and less vulnarable than many other countries, which even more confirms that all the fuss and all the the country does about Covid is highly exaggerated. 

 

 

[ourmanflint]

2 hours ago, ukrules said:

Yes, I suspect it's a combination of humidity and temperature.

 

For example, do you know just how humid it is in Wuhan?

 

Wuhan :

 

Bangkok :

 

Not much difference, eh. Of course the temperature is very different.

 

Perhaps 'absolute humidity' plays a part.

 

So I think we're looking at humidity plus temperature.

 

Humidity plays a big part because the main transmission vector of the virus is by aerosols, not by droplets, not by touching things. Unfortunately health organizations are scared of this because they think people will also be more scared of what is essentially an airborne virus

[DrTuner]

16 minutes ago, ourmanflint said:

Humidity plays a big part because the main transmission vector of the virus is by aerosols, not by droplets, not by touching things. Unfortunately health organizations are scared of this because they think people will also be more scared of what is essentially an airborne virus

It's a good thing if it's aerosols mainly. Those are far easier to avoid than touching things, just stay at safe distance and wear a proper N95 mask if you can't. Same as at the onset of the flu seasons, stay away from crowded places.

 

Not that the virus is anywhere near dangerous as it was touted to be in the beginning, though.

Edited October 16, 2020 by DrTuner