Are these respirators spewing covid viruses?

[chirhone]

This is an ER doctor in New York with a respirator with cartridges.

Due to shortages of the N95. There are hundreds of doctors in my country using them too. I even bought one. But I noticed something dangerous. The exhalation valve has only a thin rubber flap that moves when you talk or exhale (see pictures below). If the person wearing it is COVID-19 positive, can he/she spread the virus in the ER to the patients without covid?

I actually discussed this with a brain surgeon who was also using it. Then she realized only a thin flap stands the way between the wearer and outside, and there is not even any filter. There are hundreds of others who may not be aware of this.

I'd like to confirm it with people familiar with this. Can the exhalation valve of this indeed let out viruses from the wearer? If it really can. I will warn the hundreds of doctors and frontliners using it in my country. They may be releasing more viruses into other patients.

This is the breakdown of the units:

The small thin rubber flap at center above moves out when you speak or exhale inside the respirator. What if the wearer is Covid positive and exhale or cough out? Can the virus be released directly into the lying patient below the doctor or frontliners (like below actual) wearing it?

 

[BillTre]

The short answer is probably yes.

Since there is no filter on the out-going air the only entrapment of exhaled virus would be if virus particles stuck to the inside of the mask and other exposed surfaces.
This is similar to the situation in a previous post somewhere around here where filtered air was being pumped into a face mask or helmet of some kind. Its great for protecting the wearer but does not prevent spread from them to others.
Therefore it would seem to only be appropriate for confirmed non-infected people (if that exists).

 

[phinds]

Therefore it would seem to only be appropriate for confirmed non-infected people (if that exists).

I disagree completely. Yes, the mask can allow exhalation of contaminated particles but what it does NOT allow is the "spewing" of those into a wide area the way you get if someone is breathing or talking out into the open air in front of them.

Cloth masks are also useless for preventing the exhalation of contaminated gas but they also block "spewing". That's why these masks are both good for contaminated people to wear and that's why cloth masks are now being widely recommended. For cloth masks in particular it's far more useful for contaminated people to wear them than for uncontaminated people to wear them.

 

[BillTre]

I disagree completely. Yes, the mask can allow exhalation of contaminated particles but what it does NOT allow is the "spewing" of those into a wide area the way you get if someone is breathing or talking out into the open air in front of them.

Seems like there would be a faster airflow out of the vent since the same volume of air funneled through the small opening would have to travel faster than that it would be going through the "open air in front of them". This could, depending on the details, push contaminants out further.
As I said above, the only way the virus would be removed (equivalent to filtered) would be if it were to stick to the inside of the mask, valve, etc..

 

[phinds]

Seems like there would be a faster airflow out of the vent since the same volume of air funneled through the small opening would have to travel faster than that it would be going through the "open air in front of them". This could, depending on the details, push contaminants out further.

The exhalation vent on these types of masks point down, not out.

As I said above, the only way the virus would be removed (equivalent to filtered) would be if it were to stick to the inside of the mask, valve, etc..

Since we agree on that it seems pointless to belabor it.

 

[BillTre]

The exhalation vent on these types of masks point down, not out.

OK, but they could still contaminate a local area.

 

[phinds]

OK, but they could still contaminate a local area.

Absolutely. I have a mask somewhat similar to the design shown and it is a "P100" which means that it is considerably better than the "N95" masks that doctors and nurses use when treating known contagious patients, BUT ... my mask not only has unfiltered ehxalation, even worse it drops beads of condensed breath. Most of the condensation accumulates in the mask and I just wipe it out with a paper towel when I'm done, but sometimes drops come out the bottom. For me this is a major annoyance since it gets drops of moisture on the wood I'm working on but if I were a doc hovering over a patient I was treating, I could inadvertently drop what I think amounts to bodily fluid directly on his/her face.

 

[BillTre]

Guess I don't undestand why you are arguing about this then.

 

[phinds]

Guess I don't undestand why you are arguing about this then.

Because my point is those masks are more for the infected to prevent them infecting others that for the uninfected to not get infected. This is exactly the opposite of what your original statement was:

Therefore it would seem to only be appropriate for confirmed non-infected people (if that exists).

 

[BillTre]

That is in reference to who is wearing the mask and how appropriate it is.
It works to protect the wearer, but would only be good for others if the wearer is not infected.

 

[hutchphd]

I am slightly mystified by this entire discussion. A surgeon wears a mask to keep from contaminating the surgical field. These ER docs wear masks to keep from becoming contaminated themselves.
In each case that is the greater good and the appropriate mask.

 

[phinds]

That is in reference to who is wearing the mask and how appropriate it is.
It works to protect the wearer, but would only be good for others if the wearer is not infected.

We still take exact opposite points of view about this, and my point of view is the one of the medical experts. Just to be sure we're not arguing about definitions, here's how I perceive it:

Paul: masks useful to protect the wearer from infection but are also for the protection of the uninfected from the infected who are wearing the mask, so EVERYBODY should wear them.

Bill: masks are only useful if UNinfected people wear them.

 

[phinds]

I am slightly mystified by this entire discussion. A surgeon wears a mask to keep from contaminating the surgical field. These ER docs wear masks to keep from becoming contaminated themselves.
In each case that is the greater good and the appropriate mask.

You are leaving out the general public where the primary purpose of masks is to protect the uninfected from the infected, which has been my whole point in this thread.

 

[BillTre]

Paul: masks useful to protect the wearer from infection but are also for the protection of the uninfected from the infected who are wearing the mask, so EVERYBODY should wear them.

This would be ideal, but it only works with masks that filter both inflow and outflow.

The only way an unfiltered outflow mask would meet those goals if it was used by someone who was known to be uninfected, which I don't know if that is really done, thus:

confirmed non-infected people (if that exists)

If people are using those masks, which seems to be the case, then they would only be suitible in the above sense if the wearer was a confirmed uninfected person.

 

[hutchphd]

Your original picture showed an ER doc with a one way valve mask. My point was that his primary objective is different from that of the the general public for whom a surgeons mask makes perhaps more sense.

 

[phinds]

This would be ideal, but it only works with masks that filter both inflow and outflow.

The only way an unfiltered outflow mask would meet those goals if it was used by someone who was known to be uninfected, which I don't know if that is really done, thus:


If people are using those masks, which seems to be the case, then they would only be suitible in the above sense if the wearer was a confirmed uninfected person.

So, your preference would be that the general public not bother wearing masks because they are not perfect and are therefore useless, it seems. We're never going to agree on that.

 

[BillTre]

So, your preference would be that the general public not bother wearing masks because they are not perfect and are therefore useless, it seems.

Well, this is a completely unfounded and unsupported conclusion, not based on what I was saying.

I think we are basically in agreement, however you seem to be focused on misinterpreting what I say (), so I will be dropping this.

 

[phinds]

Well, this is a completely unfounded and unsupported conclusion, not based on what I was saying.

I think we are basically in agreement, however you seem to be focused on misinterpreting what I say (), so I will be dropping this.

Well, you are correct that I did not believe that was your intent, so I should not have phrased it so harshly.

@BillTre I have a horrible habit of getting snippy when I'm frustrated. I apologize.

I'm still not convinced that we completely agree but my side of the discussion could have been more constructive.

 

[chemisttree]

The N95 masks worn by healthcare workers. Many have unfiltered, valved exhaust. Very bad if the nurse is an asymptomatic carrier.

 

[phinds]

The N95 masks worn by healthcare workers. Many have unfiltered, valved exhaust. Very bad if the nurse is an asymptomatic carrier.
View attachment 261277

Not only that, the exhaust hole points outward. At least the masks in discussion when this thread started have a downward pointed exhaust hole.

 

[chemisttree]

Yep! Still wouldn’t want to be in the same viral cloud as an infected nurse with one of these.

 

[hutchphd]

The nurse wears the mask to protect himself. He is not attending church, he is dealing with a sick person!1! This is not complicated....

 

[chemisttree]

Exactly! Would you remove your N95 in the presence of an infected asymptomatic coworker wearing one of these? Bet you wouldn’t think twice! Cough! Cough!

 

[hutchphd]

No. Your ER coworker is also festooned with potential contamination, so I don't do not know what the big deal is. No you would not.

 

[chirhone]

So these masks with direct exhalation valve direct in front are dangerous because it can spew out contaminated breath? There are no less than 70 frontliners in ER using these in our hospitals. They don't know the dynamics of breath flow.

Before I warn our government about this. I need to know what happens in ordinary surgical masks used by millions of our populations in lining up at groceries or markets 1 meter apart.

When one coughs in surgical masks. So the spew is trap in the masks. But what about the sides. How many percentages of particles can escape from the sides and what are their velocity and distance?

How about an N95. When one coughs inside N95. Where would the particles escape compared to the surgical masks?

 

[berkeman]

This would be ideal, but it only works with masks that filter both inflow and outflow.

Yeah, I don't know of any that do that yet. And IMO that would be weird, and part of a very difficult end-game for humanity. "We need to treat you, but we are contagious, so we are using bi-directional PPE"...

AFAIK, respirators with filters like that are 1-way to protect the provider. And as a practical matter in my experience simple N95 masks let some of our breath out during our expiration, but seal better during our inspiration. It looks like the newer versions this year seal tighter, but their focus is still to protect us providers on inspiration.

Just think about CPR masks... They use 1-way valves to let my rescue breaths pass into my patient (Pt). My Pt catches any respiratory diseases that I'm carrying when I do CPR on them... (which will generally be none, obviously).

https://www.dsi-nj.com/newsite/wp-content/uploads/2015/09/pocket-mask.jpg

 

[chirhone]

So these masks with direct exhalation valve direct in front are dangerous because it can spew out contaminated breath? There are no less than 70 frontliners in ER using these in our hospitals. They don't know the dynamics of breath flow.

View attachment 261292

View attachment 261291

Before I warn our government about this. I need to know what happens in ordinary surgical masks used by millions of our populations in lining up at groceries or markets 1 meter apart.

View attachment 261293


When one coughs in surgical masks. So the spew is trap in the masks. But what about the sides. How many percentages of particles can escape from the sides and what are their velocity and distance?

How about an N95. When one coughs inside N95. Where would the particles escape compared to the surgical masks?

Ive been trying to analyze this for an hour. Imagine the person coughs into a surgical mask. The mask can stop the droplets as they say. But what about the breath that escapes from the sides. I don't know the physics of particles and air. I am visualizing as the droplets hit the mask fabric. It is trap there. Or could the droplets richochet from the fabric? If we are talking about bullets ricocheting a wall. It can happen. But droplets ricocheting fabric? Can it happen. If not, then the breath that escapes are already pure?

 

[chirhone]

Ive been trying to analyze this for an hour. Imagine the person coughs into a surgical mask. The mask can stop the droplets as they say. But what about the breath that escapes from the sides. I don't know the physics of particles and air. I am visualizing as the droplets hit the mask fabric. It is trap there. Or could the droplets richochet from the fabric? If we are talking about bullets ricocheting a wall. It can happen. But droplets ricocheting fabric? Can it happen. If not, then the breath that escapes are already pure?

This article is relevant: https://annals.org/aim/fullarticle/2764367/effectiveness-surgical-cotton-masks-blocking-sars-cov-2-controlled-comparison

"In conclusion, both surgical and cotton masks seem to be ineffective in preventing the dissemination of SARS–CoV-2 from the coughs of patients with COVID-19 to the environment and external mask surface."

"Of note, we found greater contamination on the outer than the inner mask surfaces. Although it is possible that virus particles may cross from the inner to the outer surface because of the physical pressure of swabbing, we swabbed the outer surface before the inner surface. The consistent finding of virus on the outer mask surface is unlikely to have been caused by experimental error or artifact. The mask's aerodynamic features may explain this finding. A turbulent jet due to air leakage around the mask edge could contaminate the outer surface. Alternatively, the small aerosols of SARS–CoV-2 generated during a high-velocity cough might penetrate the masks. However, this hypothesis may only be valid if the coughing patients did not exhale any large-sized particles, which would be expected to be deposited on the inner surface despite high velocity. These observations support the importance of hand hygiene after touching the outer surface of masks."

About this "turbulent jet due to air leakage around the mask edge". Again my question in previous message, can't the particles get deposited in the surgical mask fabric even with turbulent jet, or does it mean the particles swirl around without touching the fabric and goes out? This is key to understand surgical masks leakages.

 

[chirhone]

Yeah, I don't know of any that do that yet. And IMO that would be weird, and part of a very difficult end-game for humanity. "We need to treat you, but we are contagious, so we are using bi-directional PPE"...

AFAIK, respirators with filters like that are 1-way to protect the provider. And as a practical matter in my experience simple N95 masks let some of our breath out during our expiration, but seal better during our inspiration. It looks like the newer versions this year seal tighter, but their focus is still to protect us providers on inspiration.

Just think about CPR masks... They use 1-way valves to let my rescue breaths pass into my patient (Pt). My Pt catches any respiratory diseases that I'm carrying when I do CPR on them... (which will generally be none, obviously).

https://www.dsi-nj.com/newsite/wp-content/uploads/2015/09/pocket-mask.jpg

After reading the above about lack of masks that filter both inflow and outflow. I immediately went ahead of the order of the full face respirator from china whose stocks are getting so scarce.

I plan to use it when going to drug store or clinic. Initially i didn't want to get it because people may complain there is no filter in the exhalation valve. But then since surgical mask and N95 also allows exhalation outside it. Then they are similar.

This is why I want to know how exactly the surgical mask behave so I can justify using it. Also because N95 are getting so expensive and scarce the public no longer use it. What do you think will allow more exhalation out, the full face respirator above or a typical surgical mask? Bill. Please answer this.

Our president has extended our lockdownt to 2 months. He kept repeating he would only lift the lockdown if there is vaccine already and offering rewards of 1 million dollars to any who can produce a vaccine.

As the virus spreads across the world, and the scourge snips in every corner of the land. We are going to have new normal, one that will include wearing the above in public. Or other technology and protection devices to be developed (we hoped) and eventually vaccine by say the Umbrella Corporation or other powerful entities.

 

[phinds]

Our president has extended our lockdownt to 2 months

Where are you?

 

[chirhone]

Where are you?

Philippines. Our lockdown started in March 16, the president extended it to May 15, but hinted he would only lift it if there is vaccine already. I'm stuck at house and no confidence to even go out to drugstore or clinic so I need to use more protection like the full face respirator. So I want to know exactly it compares to the surgical mask in exhalation dynamics (so I can defend its use with reasonings for people who may point out there is exhalation valve present).

 

[berkeman]

Initially i didn't want to get it because people may complain there is no filter in the exhalation valve. But then since surgical mask and N95 also allows exhalation outside it. Then they are similar.

No. Respirators generally do not filter exhalations ("expirations") by the person wearing them. That's not what they are for. The are for protecting the person wearing them. A traditional N95 filter mask that is well-fitting will filter both inspirations and expirations by the wearer, protecting both the person wearing the mask and the patient they are treating. That assumes a very good fit that still works well on expiration (when the mask will tend to lift off of your face a bit if it is not tight and well-fitting).

In an EMS meeting that I was in today, an MD called out a picture of a medic wearing an "N95" mask that had a visible valve on it. He emphasized that such masks with valves like that have a 1-way expiration valve, which exposes your patient to your breath if you are pre-symptomatic for COVID-19.

https://www.zoro.com/static/cms/product/large/Z-519yfo9x4.JPG

This is why I want to know how exactly the surgical mask behave so I can justify using it. Also because N95 are getting so expensive and scarce the public no longer use it. What do you think will allow more exhalation out, the full face respirator above or a typical surgical mask?

Surgical masks do not filter out the smallest viral particles that are shed on expiration, but do help a lot to trap the liquid droplets that contain the virus. That helps to keep you from depositing such droplets on surfaces when you cough or sneeze. That's about the extent of the use of surgical masks -- they are meant to help to keep you from spreading the virus if you are shedding it and are in a public place. They are far from perfect, but still a useful step, IMO.

 

[chirhone]

No. Respirators generally do not filter exhalations ("expirations") by the person wearing them. That's not what they are for. The are for protecting the person wearing them. A traditional N95 filter mask that is well-fitting will filter both inspirations and expirations by the wearer, protecting both the person wearing the mask and the patient they are treating. That assumes a very good fit that still works well on expiration (when the mask will tend to lift off of your face a bit).

In an EMS meeting today, an MD called out a picture of a medic wearing an "N95" mask that had a visible valve on it. He emphasized that such masks with valves like that had the 1-way expiration valve, which exposes your patient to your breath if you are pre-symptomatic for COVID-19.

https://www.zoro.com/static/cms/product/large/Z-519yfo9x4.JPG

View attachment 261365

Surgical masks do not filter out the smallest viral particles that are shed on expiration, but do help a lot to trap the liquid droplets that contain the virus. That helps to keep you from depositing such droplets on surfaces when you cough or sneeze. That's about the extent of the use of surgical masks -- they are meant to help to keep you from spreading the virus if you are shedding it and are in a public place. They are far from perfect, but still a useful step, IMO.

But can't one say the full face respirator also help trap a lot of liquid droplets that contain the virus and also not able to filter out the smallest viral particles that are shed on expiration? Just like the surgical masks?

 

[berkeman]

But can't one say the full face respirator also help trap a lot of liquid droplets that contain the virus and also not able to filter out the smallest viral particles that are shed on expiration? Just like the surgical masks?

That's probably fairly accurate, depending on whether the expiration valves have any baffles in them (which they probably don't). You can stack masks to get extra protection effects if you can tolerate it. You could wear a surgical mask under your respirator to help to protect others better, for example.

 

[berkeman]

In an EMS meeting today, an MD called out a picture of a medic wearing an "N95" mask that had a visible valve on it. He emphasized that such masks with valves like that have a 1-way expiration valve, which exposes your patient to your breath if you are pre-symptomatic for COVID-19.

BTW, the MD made a semi-humorous comment about the picture of the health provider wearing the mask with the expiration valve -- "When EMS has to go to Home Depot to purchase emergency supplies, you end up with compromises like this".