# News & Current Events > Coronavirus SARS-CoV2 >  Apartment Dwellers at Higher Risk from Corona by Staying In 24/7 Breathing Recirculated Air?

## James_Madison_Lives

Is this self isolation always a good idea?  Has anyone thought this through?  Most apartments buildings are germ factories.  Go outside and stay six feet apart...

 Are Apartment Dwellers at Higher Risk from Corona by Staying Inside 24/7 Breathing Recirculated Air from Units?

https://hubpages.com/politics/Are-Ap...Air-from-Units 







> But has anyone asked the question, what of high-density apartment buildings, almost all of which rely on central air conditioning and ventilation systems to recirculate air throughout the building? Only hospital and scientific clean rooms provide room-sealing and technology to prevent air from circulating from one room into another. In most modern and not-so-modern high-density, multi-family structures, some level of air circulation from both inside and outside air is part of the plan.
> This means some air moves between apartment units, along with whatever is in that air... MORE  https://hubpages.com/politics/Are-Apartment-Dwellers-at-Higher-Risk-from-Corona-by-Staying-Inside-Breathing-Recirculated-Air-from-Units

----------


## Brian4Liberty

AFAIK, every apartment/condo in a modern building has its own isolated air system. Walls and doors might not be perfect seals, but the heat/AC is self contained in each unit.

----------


## kpitcher

An apartment complex in Hong Kong was evacuated because of concerns. There was a case of an apartment building spreading SARS in 2003. 

How? The sewage main vent pipe was broken, the sewer vented through dry floor drains and spread the virus.

https://cph.temple.edu/about/news-ev...m-sewage-pipes

----------


## nikcers

Some of the biggest sources of infection are from solid objects. If you have good ventilation you should be fine even in places where people are coughing If you have a humidifier and/or the humidity is around 50%. 

The amount of viable viruses on surfaces at 50% humidity level is dramatically lower than at 20% or 80% - so the right humidity level (we recommend between 40 - 60%) can reduce the number of viable viruses. Furthermore, viruses attach to particles which are heavier in humid conditions - this means that in a dry environment, those particles will remain airborne much longer.

Link to study results: https://aem.asm.org/content/76/9/2712

----------


## swissaustrian

> Some of the biggest sources of infection are from solid objects. If you have good ventilation you should be fine even in places where people are coughing If you have a humidifier and/or the humidity is around 50%. 
> 
> The amount of viable viruses on surfaces at 50% humidity level is dramatically lower than at 20% or 80% - so the right humidity level (we recommend between 40 - 60%) can reduce the number of viable viruses. Furthermore, viruses attach to particles which are heavier in humid conditions - this means that in a dry environment, those particles will remain airborne much longer.
> 
> Link to study results: https://aem.asm.org/content/76/9/2712


Unfortunately, the study you cited does not include evaporation.
This mention of humidity is important. However, you have to look at the combination of humidity and temperature (and pressure). 
Water droplets evaporate if the humidity level is below the natural balance between liquid and gasesous water at a given temperature and pressure (thermodynamic equilibrium of the liquid and gaseous phase). Water droplets are condensing into larger droplets that fall down more easily if humidity is well above that balance (ie rain in nature). Higher temperatures allow for higher humidity, ie the 50% value means more actual water vapor in the air at higher temperatures. 
Here is the vapor pressure curve for water 



As you can see, the amount of water vapor in equilibrium with droplets becomes more significant above 70 F.

Looking at the spread of corona in different parts of the US it is quite curious that large warm and rather dry cities like LA, Houston, Dallas have not experienced a massive outbreak (yet).

The financial times has written an article about that recently:

----------


## jmdrake

> AFAIK, every apartment/condo in a modern building has its own isolated air system. Walls and doors might not be perfect seals, but the heat/AC is self contained in each unit.


Not everyone lives in a modern apartment building.  Some older apartments don't even have sprinkler systems.  Consider this headline from 2018: Fatal Trump Tower fire: No sprinkler system in apartments

----------


## CaptainAmerica

> Is this self isolation always a good idea?  Has anyone thought this through?  Most apartments buildings are germ factories.  Go outside and stay six feet apart...
> 
>  Are Apartment Dwellers at Higher Risk from Corona by Staying Inside 24/7 Breathing Recirculated Air from Units?
> 
> https://hubpages.com/politics/Are-Ap...Air-from-Units


It is a droplet virus . If concerned get s filter that captures .01-03 micron particulates , but also beware that denser filters will effect the AC unit pressure and strain thebcompressor. droplet viruses dont float around

----------


## swissaustrian

> It is a droplet virus . If concerned get s filter that captures .01-03 micron particulates , but also beware that denser filters will effect the AC unit pressure and strain thebcompressor. droplet viruses dont float around


Yeah filters are sufficient in the sizes you mention. A single virus has about 0.05 microns (50 nanometers) in diamenter, but those droplets are several microns big. Viruses are dispersed inside these droplet clouds (aerosols).

Consider disinfecting the filters by cooking them in water or putting them into the oven every once in a while. be careful that they dont catch fire in the oven

----------


## nikcers

> Unfortunately, the study you cited does not include evaporation.
> This mention of humidity is important. However, you have to look at the combination of humidity and temperature (and pressure). 
> Water droplets evaporate if the humidity level is below the natural balance between liquid and gasesous water at a given temperature and pressure (thermodynamic equilibrium of the liquid and gaseous phase). Water droplets are condensing into larger droplets that fall down more easily if humidity is well above that balance (ie rain in nature). Higher temperatures allow for higher humidity, ie the 50% value means more actual water vapor in the air at higher temperatures. 
> Here is the vapor pressure curve for water 
> 
> 
> 
> As you can see, the amount of water vapor in equilibrium with droplets becomes more significant above 70 F.
> 
> ...


Multiple mechanisms may contribute to viral inactivation on surfaces. Some inactivation may take place when viral capsids accumulate at the air-water interface (AWI) of a solution, causing structural damage (30, 31, 33). Desiccation may also be an important contributor to inactivation on surfaces (1), as loss of water molecules triggers lipid membrane phase changes, cross-linking, Maillard reactions, and peroxide formation (9). Virus inactivation on surfaces may involve both desiccation and interaction at the AWI, with the contribution of each depending on the RH. At a low RH, oxidation and Maillard reactions that occur during rapid desiccation may predominate. Around 80% RH, the rate of loss of water molecules is slowed, the hydrophobicity of the AWI is decreased (19), and the main mechanism may be inactivation at the AWI. Around 50% RH, inactivation at the AWI and desiccation may occur simultaneously; as water molecules are lost, lipid oxidation and Maillard reactions occur (the maximum rates of Maillard reactions occur when the RH is 50 to 80%) (9), possibly providing a partial explanation for why viral inactivation appears to be more rapid at 50% RH than at 20% or 80% RH.

----------


## swissaustrian

> Multiple mechanisms may contribute to viral inactivation on surfaces. Some inactivation may take place when viral capsids accumulate at the air-water interface (AWI) of a solution, causing structural damage (30, 31, 33). Desiccation may also be an important contributor to inactivation on surfaces (1), as loss of water molecules triggers lipid membrane phase changes, cross-linking, Maillard reactions, and peroxide formation (9). Virus inactivation on surfaces may involve both desiccation and interaction at the AWI, with the contribution of each depending on the RH. At a low RH, oxidation and Maillard reactions that occur during rapid desiccation may predominate. Around 80% RH, the rate of loss of water molecules is slowed, the hydrophobicity of the AWI is decreased (19), and the main mechanism may be inactivation at the AWI. Around 50% RH, inactivation at the AWI and desiccation may occur simultaneously; as water molecules are lost, lipid oxidation and Maillard reactions occur (the maximum rates of Maillard reactions occur when the RH is 50 to 80%) (9), possibly providing a partial explanation for why viral inactivation appears to be more rapid at 50% RH than at 20% or 80% RH.


That quote does not talk about evaporation. I talks about chemical reactions with surfaces and water de/absorbtion from viridae at the water/virus boundary. Still a good publication, though

----------


## nikcers

Dry cities didn't get hit as bad because people in dry cities tend to not live on top of each other as much if we had done nothing it would of gone bad. Also no subway system and New York gets the most Chinese tourists.

----------


## Brian4Liberty

> Not everyone lives in a modern apartment building.  Some older apartments don't even have sprinkler systems.  Consider this headline from 2018: Fatal Trump Tower fire: No sprinkler system in apartments


I'm mostly familiar with condos and apartments that I have lived in. I do know that really old buildings depended upon every unit having external windows for fresh air. They did not have central air which would be shared. They did have steam radiators for heat, but those are radiant and sealed.

But now that I think about it, a dorm where I lived in college did have a shared air circulation system. Definitely not a new building. They were just rooms, not apartments. I have never seen an apartment built like that, but they probably exist out there somewhere. This may be why all of the college dorms were shutdown so fast.

----------


## Brian4Liberty

> Some of the biggest sources of infection are from solid objects. If you have good ventilation you should be fine even in places where people are coughing If you have a humidifier and/or the humidity is around 50%. 
> ...


No, you won't be fine sitting next to someone who is coughing if the humidity is around 50%. 

Humidity and temperature are extremely important, especially when talking about airborne transmission. The higher the temperature, the better to kill the virus. The higher the humidity, the better to take the virus out of the air. 

But that paper focuses entirely on surfaces, not airborne. It isn't even addressing airborne transmission.




> Effects of Air Temperature and Relative Humidity on Coronavirus Survival *on Surfaces*


From your paper:




> Inactivation was more rapid at 20°C than at 4°C at all humidity levels


The higher the temperature, the better. The higher the humidity, the better to stop airborne transmission.

The study found that at humidity above 80%, it helps the virus survive longer on some surfaces, but *not* in the air.

Washing surfaces and hands will always be part of prevention, but it is by no means the only route of transmission.

----------


## nikcers

> No, you won't be fine sitting next to someone who is coughing if the humidity is around 50%. 
> 
> Humidity and temperature are extremely important, especially when talking about airborne transmission. The higher the temperature, the better to kill the virus. The higher the humidity, the better to take the virus out of the air. 
> 
> But that paper focuses entirely on surfaces, not airborne. It isn't even addressing airborne transmission.
> 
> 
> 
> From your paper:
> ...


I have lived in a lot of apartments and never had someone cough next to me lol. I meant places that have a lot of cases.

----------


## Brian4Liberty

> An apartment complex in Hong Kong was evacuated because of concerns. There was a case of an apartment building spreading SARS in 2003. 
> 
> How? The sewage main vent pipe was broken, the sewer vented through dry floor drains and spread the virus.
> 
> https://cph.temple.edu/about/news-ev...m-sewage-pipes


Interesting hypothesis. The story says that nothing has been confirmed as far as how the disease was actually transmitted. Could have been elevator buttons or air in a hallway or elevator.

You would think that sewer air coming in would also bring a bad smell, but some people might not notice it.

----------


## kpitcher

> Interesting hypothesis. The story says that nothing has been confirmed as far as how the disease was actually transmitted. Could have been elevator buttons or air in a hallway or elevator.
> 
> You would think that sewer air coming in would also bring a bad smell, but some people might not notice it.


Possibly, although it might not be all that bad of a smell and still be venting. I've been around dry traps, usually it's the catch a whiff every now and then of something but faintly and hard to identify.  Most people don't assume a floor drain, or the floor drain is half covered and they don't even know they have one. There is non evaporating liquid you can put in traps that never get water to stop that issue.

----------


## nikcers

> An apartment complex in Hong Kong was evacuated because of concerns. There was a case of an apartment building spreading SARS in 2003. 
> 
> How? The sewage main vent pipe was broken, the sewer vented through dry floor drains and spread the virus.
> 
> https://cph.temple.edu/about/news-ev...m-sewage-pipes


How many bleach tablets do I need to put in the reservoir to stop this from happening?

----------


## kpitcher

> How many bleach tablets do I need to put in the reservoir to stop this from happening?


If it is an rarely used trap that rarely, if ever, is used as a drain, just put something other than water that doesn't evaporate in the trap. They sell a variety of offerings at hardware stores, or a little mineral oil.

----------

