This week Fred and Luis review the latest insights in air handling mitigation and what we have learned over the last year on the transmission of COVID19 through aerosol and droplets and what that means for meetings, college classrooms, dormitories and office meet places. They discuss the various options available for mitigation including ventilation, filters, fans, UV lights and of course masking
Our weekly question and answer session with Fred Goldstein, Dr. Luis Saldana, and Nick van Terheyden, MD on our COVID Insights to Action Discussion webinar that takes place live every Wednesday at 4pm ET You can register here
You can also find our training modules and services available to help businesses, education facilities, and employers get their employees, staff, customers, and students back to work and school safely in the context of COVID19
Raw Transcript
Fred Goldstein
Hello, everyone, and welcome to this week’s COVID insights to action discussion group. I’m Fred Goldstein den this week, I’ll be joined by Dr. Louis cell donya, one of the physicians that work with them. And Nick van Terheyden, unfortunately, couldn’t be here this week. This week we’ll we’ll be discussing air handling in the workplace and its schools. So let’s start off first, with a bit of a discussion Luis on things over the past year have obviously changed and air handling has become more important. What’s the difference?
Luis Saldana
Well, Fred, I think a big part of this when we, when we first started with this virus, or were first started seeing this virus coming out of China, it was very unclear how this was spreading. And I, you know, I think just from a public health perspective, you look at the traditional ways that that microbes spread. And that is multiple ways. There’s not It’s not often not one single way, but direct contact in some form or fashion. So I think what we call what we call fomites, which a lot of times is surfaces, shaking hands with somebody, those type of things that cause direct physical transmission, was probably considered a big factor early on, that’s why our, you know, wash off your groceries, clean off your groceries all day, there was a lot of things there. And I think a lot of that was, was probably appropriate, because we didn’t, we weren’t entirely clear on on what the modes of spread are. And like I said, they pathogens can use different paths to spread, they can’t just be all one way they can make them spread in different ways. But I think we know based on the experiences, we’ve had a lot of cases and things that, that what we’re seeing is that this is spread through by respiratory droplets. So respiratory, it’s largely a respiratory virus. And so things that generate droplets, what we call droplets, and to kind of, I think most for most people to kind of visualize this, you’ve probably seen a YouTube video of somebody sneezing, and they show this kind of graphic of the particles kind of going out there. So really think about creating these particles that go into the air, and sneezes just a perfect example of how far these particles can be spread. We call those particles droplets. And there are various sizes, depending on the virus and things like that, so that you hear things about droplets spread and an airborne spread, the difference between the two is kind of a gray area, it’s not a black and white area, a lot of it’s due to the size of the droplets. Certainly this is not a purely airborne virus, because if it was purely spread through air, I mean through air, not airborne, but aerosol, it was purely spread by aerosol, we would see much faster spread like like you see with with like the measles, I mean, it’s almost, you know, it’ll pass much more, much, much more. So again, it’s respiratory droplets is spread, and these can be mitigated. Certainly by distancing and masking those two those are the two big things there and and the topic for today, ventilation, filtration, all of those things are really really relevant because that determines your risk of spread, I think any risk of encountering this virus
Fred Goldstein
and so if I think of this is a normal individual, the droplets because they’re larger travel less distance and then tend to fall as I understand it, whereas an aerosol will more remain within the space in the air.
Luis Saldana
Yeah, and that’s just again a matter of size of the droplet so the bigger droplets are gonna they’re gonna tend to drop dropped out the smaller droplets are gonna tend to hang in the air again, the there’s not like a clear demarcation between this aerosol and, and and droplets spread. I think there’s some people that really get into it that are real purist and say, Oh, no, it’s air is there. You know, aerosol, there’s really no reason to even argue about that point at all. From a public health perspective. It’s it’s a respiratory droplets virus and that i think that’s that’s kind of the important thing. And so the thing we should be aware of is, is respiratory what happens to these droplets, large and small, when they kind of come come come out of us, while we breathe costs, nice thing, shout all these type of exercise these type of activities.
Fred Goldstein
And I know early on, when Nick and I were doing some exploring this back in March and April, there was a study out of China that showed this restaurant where individuals were sitting around a table, and there were three essentially tables in a row. And then there were some other tables in another row. And that is circular tables. And they identified one individual that have been infected. And then they had perhaps nine others at the at that table and others that got infected. And they noticed that there was a ventilation system fan right at the end that was sort of taking air in that direction across the three. And interesting enough, the other two tables that were in a different row didn’t have any infection in them. So that started too early on, I guess, point to this issue of how that virus moves and is transmitted.
Luis Saldana
Yeah, as a matter of fact, today, because today, yeah, CDC put out there and who knows that the case just very similar to what you described from a fitness center. And a big part of it was was one fitness instructor and the use of a floor fan. So that actually, you know, was was the same way was was, was spreading this even more. And even though they had like bicycles, just six feet and things like that, that there wasn’t masking, they took the other precautions, but but again, that’s still you know, it’s still you have to think about that, and that visually described with that is, is a good way to think about when you walk in a room, what what are the dynamics of air flow in this space.
Fred Goldstein
And that raises a great point, as you, as you pointed out, they put in these fans. And you really do have to think about directional airflow, you do not want that flow going from an individual who’s infected through that room to somebody else. And that creates all kinds of issues, you think about error handling. And I think one of the other studies that we looked at was exactly that issue was, were over a 15, or more foot distance, because of the way that airflow was, somebody was able to be infected. Because it was so directional and taking the, the particles and the virus through. So even as you think about airflow just initially Don’t think about, you need to think about you don’t want and people talk about this, well, if we have two sides of a tent, and we got a wind blowing through that, well, you’re going to create a problem for the people that are further down. So you think about building your rooms out and how you might want to control ventilation, watch for those kinds of issues. So what are some of the things that people should be considering as they look at airflow within a room? What are some of the basic considerations to try to improve that?
Luis Saldana
Yeah, well, I think the directional airflow like you talked about eBay been mentioned a little further along, I think the one about the Ubers, or whatever, I think in a car, how you should add that we can touch, you can touch on that a little bit later. The biggest thing is, when you walk into any space, let’s say you’re a crowded restaurant, those types of things. That’s where this occupancy thing becomes important, like 25%, occupancy, 50%, affricates, the 75% occupancy, more people you have in a closed space, there’s going to be a lot more production of, of aerosols and respiratory droplets. So that’s where ventilation and filtration become extremely important. What’s happening to these respiratory droplets. Are they being filtered out. And so what this is when you get into some of the measurements that are that are direct and indirect measurements of filtration and ventilation, there’s kind of two factors that you’re more of an expert of this than I am. But you know discuss filtration and ventilation. Those are two things you should think about what I think when you walk into a space is like what’s what’s the airflow in here? What’s what are the dynamics of ceiling heights? Are there fans, where are all the people concentrated, but you know, the air change, we talked about these air changes per hour to very simple ones are air changes per hour. And then these handheld co2 meters can be quite useful on on looking at how much air is not being moved out co2 as we exhale co2. So as we are in a crowded space, if there’s a lot of co2 relative that tells you something.
Fred Goldstein
Yeah, and you bring up the point. So it’s about, you know, the airflow and air exchange and filtration and you think about them. So one of the simple things obviously do open the doors. Windows, you know, in, in Germany, I know at the schools, they opened all the windows, I happen to get my haircut. months ago, I went for the first time and I had gotten so long, I had to go. And I went into somebody who had done my hair for years. And she said, Oh, it’s gonna be safe, it’s gonna be great, we’ve done all the things, and I went into the place. And I immediately got scared, too many people in there a fan in the corner blown one direction, people taking their masks off as they’re leaving the client, you know, and it was a number of things. But clearly the airflow in there was enough, and I left. But I went to another place that got recommended and had some really good reviews. And sure enough, they were doing the right things. And, and making sure that everyone was wearing the mask of things, but I did tell them, you know, one of the things you may want to do, it’s a nice day outside, open your door, you just open that door, and upon intervention event back there that’s over the, the where they’re cutting hate where they’re washing your hair, and go ahead, and I noticed it’s closed, you know, try to get a little more air circulation in this and running through that filtration system. So all of those things, obviously are very simple. Nick’s talked about where the gyms have opened up the doors and some windows and things. We know there’s a huge differences, obviously, between indoor transmission rates and outdoor, right. And and the other area you talked about was filtration. And so when you think about filtration, obviously everyone by now probably knows Merv 13. But the standards by ASHRAE, the American Society of heating refrigerants and air conditioning engineers. And that’s who the CDC really turned to and said, You know, this space, what should people be doing around that, and they looked at it and said, you know, to filter out these types of particles, look to Merv 13 filters, and understand to I mean, if you’re a homeowner or a small business, there are different three different standards for filtration, there’s the Merv standard, three M has their own, and then Home Depot has their own. And so there’s an equivalence across the three measurement tools. And so if you think about that, if you’re going to go from Merv 13 filter, and it’s not by them, it’s three m, it’s going to be between 15 118 100 1900 is what we’ll say. And if it’s at Home Depot, it’s going to be called an FPR 10. And that’s their highest rating. And, and, and I can tell you from experience having played with these and put them in the house, there, they were very tough for my system to handle it in a sense. And I could tell that because when I took them out, they’d actually been bent up from the increase in pressure that they create. And that’s created differences, different difficulties, obviously, for various companies, as they’ve thought about how do we put in these higher quality filters, you maybe you can’t get a 13 to work, but an 11 might be okay. And just up that scale, I know when I talk to my AC guys, they come out every six months, and they said, the typical filter, put it in the house is about a Merv eight. And, and so obviously less of an issue maybe in your home, but in your workplace, if you look at that, and one of the other things that people have been doing, obviously, is taking that h HVAC system and bringing in as much external air as you can through it, it can be adjusted. Obviously, obviously, you’re in Texas, some of our clients here in Texas been incredibly cold, probably impacted the ability of the system to be able to even take that air in and heat it enough to make it work. which creates other difficulties, obviously, from that perspective.
Luis Saldana
Yeah, absolutely. No, those are all excellent points. Right.
Fred Goldstein
The other area that I think is fascinating, and you mentioned a little earlier, is this area of what do you do in a vehicle? Yeah, and there were some fascinating studies on that, obviously, if you can open all four windows that helps you know, if you want to keep separation, the driver’s seat and the rear right side passenger seat is the way to go in the US, I guess, if you were with Nick in the UK, you might reverse that. But setting that up, but the study was fascinating, they actually looked at airflow within a car. And and both from this question of what which window pulls the air out, and which one pushes it in and and where the flow goes. And they determined that the best situation if you can open all four, which was completely different from what I would have anticipated was to open the passenger side front window and the driver side rear window. And that creates actually a little bubble around the driver and keeps the flow from going either direction diagonally to a much lower extent in terms of airflow in a car and they measured it using those little ones with little threads on them to see which way the wind was going. And then computer simulated it. So there are a lot of things obviously in transportation you consider around that as well. In terms of double masking, that’s obviously come up now Luis are higher quality masks. What’s the thinking on that? Especially indoors?
Luis Saldana
Yeah, the main thinking the primary reason is what we call source control meaning What I am putting out in terms of my respiratory droplets? How can I diminish that the most and prevent, you know, that from from spreading. And you know, the idea is, you know, I think initially we kind of saw that all masks you saw bandanas you saw kind of Eric kind of all kinds of all comers. As far as that goes to those the The first thing and also because of the big shortage of true what we call PP or personal protective equipment and, and the kind of the gold standard of the N 95. mask, which is really a respirator which really kind of prevents that, really, that that’s kind of the two way protection. And again, that’s mask still have that two way protection, but it prevents that it really prevents the those droplets from from passing through and getting to you both ways, I think is kind of the goal. And really the goal, as we’ve gotten into this, is we see that the efficiency of all the masks are out there, there’s a broad spectrum, and we’re trying to narrow that spectrum to the most effective, how do we actually reduce respiratory droplets. And I think, you know, a lot of it is common sense, being sure it’s a good pity mask is probably the most important rather than that. They think that in layers, you’d like to have multiple layers, because then these droplets, you’re trying to weave their way through through this, this mask, if you think about it that way. So So layers and and snug fit, those two things are the critical, a lot of times double masks will help in that regard by having maybe a surgical mask on and then maybe a cloth mask over that. But it adds layers and that also helps the smile a bit. You see people were actually like a mask, what do they call it little frame almost over that you put your mask over as well, that helps with with a lot of the the standard issues and things. But the idea is really taking that to the next level, especially with the variants that are out there now. And potential for for you know, they be able maybe a little bit differently, really important to kind of reduce the sources of these respiratory droplets.
Fred Goldstein
Yeah, and I believe the way they said it is the best thing to do is to put the surgical type mask on first, and then cover that with a cloth mask. And I noticed when I’m doing that, I definitely can tell I have a better fit. And one of the simple ideas they said, at least from what I’ve read is that if you as you breathe, if you can feel the mask kind of go out and come back in, you’ve probably got a pretty good seal because it’s not going out the sides. And and I noticed that obviously much more when I put on the the cloth mask over the top of that surgical type mask. In terms of going indoors. One of the other areas we haven’t touched on yet is this idea of using portable heppa filters and things. And particularly, I’m wondering, as you go into more rooms that tend to be more enclosed restrooms, obviously, as a potential for doing some things in a room like that by putting in some sort of additional filtration or watching how that air is coming out and coming back in to that room because those tend to be very enclosed. And a lot of times, not a lot of great airflow in there.
Luis Saldana
Yeah, that’s right. That’s right. And I guess we can also think about airplane, the airplane situation. And, you know, I think they have a high change of, you know, air changes per hour. And I they also use the app of filters that but filters are also, you know, really, really valuable tools I think for for this and that another consideration for I think when you look at workplaces, I think as people are going to start returning to work. That’s kind of a main thing that we look at. Now is the time to really be looking at these factors in your workspace. Another consideration that really hasn’t been big. And you see a lot of this still is physical barriers, the Plexiglas barriers, really in a lot of the, you know, the the aerosol proponents really poopoo that because aerosols can pass it over and around these these things as well. So and not that there’s not an appropriate use for some physical barriers like that. It is there might be some, some conditions where you might use that, but don’t let those kind of give you a false sense of security. For for these kind of considerations, especially as we look at returning to work, I think the things you’re gonna look at, evaluate your workplace, how many people are going to have their test? Are you when you test things like these? The you know, you need to be testing these air changes per hour, look at co2 levels with different capacities. So those type of things are important. How are you going to handle meetings? You know, are you going to Are we going to walk back into all physical meetings, you know, maybe the zoom meeting is going to Ended up being our our longer term solution anyway, even if you’re in a physical space. Now, you remember the Oh, it was a big trend towards open offices. All of that has to be reevaluated, I think, right. You know, a lot of businesses really have are thinking through this. I think that, you know, the main reason I think we went to this discussion is to really get people to start thinking about this, and, and really, you know, develop a plan, and we can certainly that’s an area, I think we can certainly help to kind of give folks some real direct guidance and direction on that.
Fred Goldstein
Yeah, absolutely. And, and, you know, the other areas that we’re starting to see some things about are UV, and putting UV in these systems. But there’s still a lot of question as to whether or not the UV will work, because you’ve got, you’ve got issues, especially in an air handling system of time that that particle flows by the UV light, and whether that time period is enough to to knock down the virus. And, and, and so there’s still some more study, I know that needs to be done on that. And they’re looking at that issue as well. Another one of the interesting studies I looked at was this spread over in one of the countries over in Asia, in which they noticed that individuals on multiple floors above each other, were all affected. Yeah. And they determined that actually, the air handling system in the restrooms, was just pumping the air out into a direct pipe that then went out through multiple floors up through the roof. And so it was actually floating up and being shared in these bathrooms on continuous floors above that first one, or actually below them as well. And, and it was spread that way. So looking at the system as well, to ensure you don’t just have these, in essence, direct connects. And sometimes I think about in the hotel, well does that vent go across to the room, the other side and just straight through, or things like that, obviously, were an issue. So it creates a lot of things that, you know, people need to look at when they consider air handling. The other one, you mentioned air changes per hour and measuring stuff like with co2. And the typical air change per hour is about one. I think in ICU and hospitals. It’s about 20. You know, or an N o r. And I know that when I went down and visited health city, Cayman Island, they were so proud that they were doing 22 air changes an hour and their ICU. So a big issue to look at are you oh six and above, I think is what people are looking
Luis Saldana
at what’s an airplane for an airplane also has a very large number, I think,
Fred Goldstein
yeah, they do. And if I remember correctly, it’s it’s three, essentially, every three rows has a system that’s researching that air and running it through rapidly. So that’s that’s obviously one of the ways to keep it within an area and also filter it out a bunch as the plane is doing. So something to consider. Another thing that you know is a clear recommendation is a lot of people’s systems just go on and say, well, offices opening up at eight, and our air handling system goes on at eight o’clock and it shuts at five. Yep, and turning that on two hours before you open. Keeping it running two hours after you close is sort of a general recommendation. But obviously, if you can run it all the time, you’re going to clear that air out much better and filter it much better than just leaving it going all the time. So one of the other interesting studies that I saw was in Starbucks, and it was in Asia and they had an individual who was working in the Starbucks, their desk not wearing a mask for a couple of hours. And I think they had about 40 people infected over two or three hour period is they contact trace that out. It did not have good ventilation. It was another clear example of that issue. The door was closed. But interesting enough, the employees all wear their masks the entire time. And not a single employee got infected.
Luis Saldana
Yeah. I think there’s some maybe some messages from the chat I’m not sure chaley are under if you can look at him easier.
Fred Goldstein
So I see one in here, improve our public health messaging and tone, coming up with different ways of breaking it down is is a great point. And I think it’s it’s you know, sometimes with any of these things, we can sound a little bit harsh maybe. And particularly as it gets to certain things like mask wearing and stuff. So as you’re right, I think the tone is is is critically important. And also, taking it to a level health literacy is a huge issue in the United States. A couple of companies have advised on health literacy programs and things like that. So taking it down to the to the level and bring it to the level where an individual can understand it or a company can understand it. And simply recommending things in a simple manner is obviously critical. The technical stuff, sometimes around AC and things, the best thing you can do is turn to the engineering company or whoever is handling that as an employer. You know, you can’t expect every employer to To understand what’s going on with that h vac system in that building?
Luis Saldana
Yeah, absolutely. And yeah, the other thing I was gonna say is, yeah, and I think as we discussed that in public health things, I think about the vaccine hesitancy thing, it’s kind of the same type thing. I think real important way on effective communication is through stories. And that’s why I like the CDC does these, and they’ll be ours, that they send out the kind of bulletin. And it really, it’s messaging, but it’s messaging through a story that then breaks down and presents all the different aspects. And that’s how we like to discuss here, as is we, you know, we brought the examples of the gym and all the different things that will tell you kind of all those things, because those everyday examples are a good way to communicate these principles. And I think that I think that gets missed by some of these, you said public health, talking ads, maybe that you see on board, we really need to kind of kind of make it relatable, and and use narrative and stories as much as we can.
Fred Goldstein
Mm hmm. Yeah. And I think you know, it, when you think about this, too, one of the things that was funny was when we were talking about the car, one where they were using this little stick with the threads on it, I mentioned that to Nick and Nick made one, and the next day went to his gym, and walked around to see how the air was flowing through the gym, you know, whether it was under event or between two bicycles or whatever. And it was fascinating. Obviously, people were looking at him pretty funny. But it’s a simple way actually, as a tool to understand a little bit about what’s going on within a given space in your facility or something like that. And understand which way the flow is going. It was also a really good example of a video and we can probably post it up that Yeah, you know, putting a fan in a room and which way to put it with the door open. And then to put the exhaust fan to get the flow, right. So it wasn’t impacting people, but was was really changing the air out in that room quite a bit. So we’ll we’ll probably send out a link to that and put that up for you.
Luis Saldana
Yeah, yeah, those YouTube videos like that are really effective ways for, for communicating this, this stuff as well, to visually sometimes really helps. These are grayed out. So like, it’d be interesting to as kids are learning from all have these kind of principles or these kind of things. discuss them in a science class. Oh, yeah, I hope they get kind of get discussed and looked at and things like that, because this is public health, how to how to how do these microbes or pathogens get get passed around? And I think it’s, it’s a valuable lesson for all of us to kind of become literate, as you said with and become more public health literate as a population.
Fred Goldstein
And it’s a great idea also for the for the universities, actually, for their engineering students to go consider what’s going on in that classroom? How is that air flowing and build that into a lesson to begin to understand this kind of stuff? Because it really is. We all sort of need to get a feel for it. Obviously, we hope that every building and people are looking at this and understanding it. But it does get very complex. So having other people come in, who can help look at it is obviously critical. Yeah. Are there any other things from an air handling perspective? I think we’ve covered the windows, we’ve covered the doors, the idea of filtration, obviously, UV light, it’ll be interesting to see what comes out with UV over the coming years, as they begin to do more studies that maybe having those in installed in certain ways will help.
Luis Saldana
Yeah, for sure. I’m not probably not as big. I think what I’ve seen on the UV light, I see a lot, a lot more investing on the other, I think would be before because it to me, just to me it makes sense about that’s only do it as it passes through, you know, it’s kind of like affecting it as it’s passing through. And so, so it’s hard for me to visualize how effective that would be. And I’m not sure we’ve seen that, that that is really effective. And I think that’s one of the ways is what are what are cost effective, effective. interventions, that’s really what I think we want to look at with businesses wireless Pat, this is a costly type to potentially costly type thing to make your workplace safe, we would focus, you know, on on the cost effective interventions. You know, I think that’s really important.
Fred Goldstein
And you raise a great point with that, that sort of goes back to early interventions, you know, remember bleaching down all the wipes and the doors and everything that I was doing forever. And companies are still spending a lot of money on cleaning surfaces. And there may be in certain cases that they may want to cut some of that back and focus more on air handling things, given the low rate I believe of transmission we’ve seen by contact. So just something to consider going forward there. I know. I see ads all the time. We’re spraying our building five times a day, you know, a restaurant is doing this and this and this. But if you go in and then you notice that not wearing a mask behind in the cooking place. I’m a little more worried about it. So it always raises some interesting stuff. So with that, I’d like to thank everybody again for joining us, it looks like we’re coming up on the end of the half hour. We’ll have another topic up for you next week. If you’d like any information, please feel free to reach out to us, and we’d be happy to talk with you about it. So thanks again for those who joined us and I hope you have a wonderful week. Thanks, everybody.
