 Welcome to the Stop COVID-Dets webinar series brought to you by the University of the Philippines. The Stop COVID-Dets shorts make it easier for you to go to the presentations that you are interested in. I'm Dr. Raymond Sarmiento, Director of the National Telehealth Center. And I'm Dr. Susie Pineda Mercado, Adjunct Faculty of the National Telehealth Center. Together, let's stop COVID-Dets. The topic is entitled Airborne or Aerosol How Is COVID-19 Transmitted? But take note that this is from an infection control from an engineering perspective. If, based on the World Health Organization, the virus is spread by infected secretions such as saliva and respiratory secretions or their respiratory droplets, which are expelled when an infected person coughs, sneezes, stops, or sinks. Infection may result if droplets reach the mouth, nose, or eyes of a susceptible person. And if you can see this infographic here, shown are the common transmission modes. So we have the droplets coming in from an infected person. Kung madapuan po yung mga kamay natin, and then ilalapat po natin sa mata, o sa ilo, o sa padig natin, yung po ang tawin natin at direct contact. However, if those droplets babagsak po sa mga surfaces, they become contaminated, we call them fomites, and then we come in contact with those contaminated surfaces, we call it indirect contact. Pwede dino po yung fecal or oral, fecal oral in a transmission mode, where from the bathroom, peding may aerosolize po yung fecal droplets, and pedig po tayong mahal ang there. But our focus today is the droplets that are expelled into the air, and the issue supposedly is it going to be airborne. Now, the irony there is that the discussion on airborne versus aerosol, there is actually no significant distinction between the two. And in fact, all of these still actually come from droplets. Now, depending on our activity, for example, talking, coughing, sneezing, they all emit different sizes of droplets. And para sa atin po, meron po tayong sizes ng droplets. Merong maliliit, ay malalaki, and shown po dito sa top left po na picture, ang relative sizes, kung ano yung micron size, and kung ano yung figure on the right naman po, is ano yung mga klasin ng mga, or sizes ng droplets na po produce ang katawan in such activities. And when you have, let's say, a cough or a sneeze, kadalasan malalaki po yung droplets ng gagawa niya. And you will see later on na babagsak po sya kaagad sa ground. However, there are smaller particles, which we call aerosols, that they are a lot smaller, they are more mobile, that even minutes after they are expelled from the body, they will linger in the air, they will float and depending on the air currents, they can travel farther and stay longer in the air and be active. As a demonstration po, this is a clip, video clip from NHQ World Japan, where we see the different sizes of droplets when a person sneezes. May malalaki, yung very big white dots, but more importantly, may mga pinong-pinong droplets and they linger. Tamatagal po sila sa air and they are distributed in ways that you cannot see. Take note po na ito mga malilitpo na droplets, hindi natin tanaki kita. Siguro ang naki kita lang natin ay mga droplets na pag naghashing ko tayo ay yung pangtulon na mga laway natin. No, that's too big. Those are very big droplets that can actually be held back by our face shields or face masks. Now, this slide shows a simulation from scientists in Japan showing how big droplets will actually be spread over time. Sinasabi po dito that the bigger droplets, itong yellow, green, and blue droplets will actually fall to the ground in about less than a minute. So, okay po yan kasi dito po nang gagaling yung initial study stati about social distancing na two meters, one to two meters, okay na po tayo. However, if we look at other activities, ito po ang isang recording naman of usual talking lab. Kita-kita po natin may mga droplets na kumakalat, naglalinger in the air, let me play that again. And they don't drop to the ground, they're just there. Now, another slide, okay, and from another source from the Washington Post, they had their own experiments as well. Ito nai kita natin na yung exhalation po natin will produce micro droplets as well. Now, of course, some people would argue, well, we already have health protocols in place. For example, face masks. But face masks napipigilan supposedly yung pagkalat, okay. And that's true, okay. We can expect that at least half of the droplets that we expel can be impeded by face masks. As shown here, even when a person sneezes, filtered out po yan. But these, there will be unideal cases. For example, if a face mask is not properly fitted or worn, this person here is on a cell phone, ill-fitted po yan na face mask niya, and you can see the plumes of micro droplets going on top and on the sides. So we should be aware that hindi po perfect yung certain measures like face masks natin. There are still certain risks, okay, from aerosol distribution. So this is a simulation po on what happens when aerosols are transmitted into the air. Now take note, aerosols, it took in comparison to the bigger droplets kanina ng mga king. Ito mas maliliit, okay. Ito mga red ngayon mas pino and they don't drop to the ground. So they linger and in this video, the simulation shows that even up to 20 minutes, nandong pa din, okay. So this can travel meters away way beyond the two-meter protocols natin. In fact, previous studies have shown that in just still air alone, when up to eight meters, but I would actually beg to differ if manantalitaing air currents, may air flow putayo, pede siyang kamanat all across the room. So this is where the transmission controversy lies. There are droplets and then aerosols are smaller droplets and the different studies, not everybody agrees on how and how much aerosols are actually produced. That's one. The other one is when we do expel a droplet, how many virus particles are in there? How many droplets are necessary to cause the infection? Now take note that I'm not a medical doctor, so I'm actually opening this discussion to our colleagues in the medical profession, but we have to agree that there is still certain ambiguity. Like how long do aerosols remain infectious when suspended in the air? I have read papers where the half-life of the virus is an hour, but another study said that it can be all the way up to eight hours in the laboratory. That's a huge discrepancy. And one of the biggest controversies is which transmission route, be it direct contact, indirect droplet or aerosol, is almost significant in a given situation. Now, even with the lack of agreement of the specific numbers, we have to, well, in general, I find that we all agree that the more time spent indoors with an infected person, the greater is the likelihood of transmission. And the thing to take away from here is that we don't really always know if the person we are with is infected or not. There are symptomatic cases. We have seen cases where they may have been vaccinated, but then they still get sick and are symptomatic. Or if we're in a hospital situation, we are tending to patients, there is still a likelihood of transmission. And from my perspective, even if it is still not proven how great a degree that transmission through aerosol is, we cannot ignore it, and instead we should just prepare for it. So these are the measures that we've done for infection control. On a personal level, we have personal protective equipment. So starting from the left, we start with face masks, and then we have face shields. To supposedly cover eyes as well. And then our medical professionals, I've seen them with half mask respirators for better filtration beyond the N95 and the surgical masks. And then we also see people donning full what we call powered air purifying respirators with the full protection. But these are on a personal level. But from a matter of information to everybody, we still have to do administrative controls. Let's see this picture here where we instruct people what to do. Tamang dispansha, wear your masks. And the first two steps here will still require the cooperation of individuals. Now if you're talking to, let's say building administrators, unit heads, legislators, we should focus as well on the last two portions, which is engineering controls where we have the opportunity and the resources and the means to set up the infrastructure, the structured environment to separate people from the pathogen and hopefully eliminate the pathogen entirely. So just as highlight here, for example, it's a very crowded office space. There are barriers here, but from an engineering perspective, I see that there are huge flaws here with respect to the ventilation and the air distribution and what I see here, it might not actually be helpful at all in controlling the infection. So we have strategies and these strategies have to be applied to different situations. We have our homes, dormitories, offices, church markets, hospitals, public places, public transportation and iba-iba po yung cases nila, some are open air, some are indoors that are naturally ventilated by windows. Sampo meron tayong mga ventilador, electric fans and then meron naman tayong mga air conditioned offices and rooms. And depending on case na yung, we will apply the general strategies slightly differently. But in general, they have the following three main brackets. We have ventilation and air distribution. We have filtration and then disinfection and sterilization. For all these strategies to be implemented, we of course require certain equipment or interventions. Like for disinfection and sterilization, we are familiar with the concept of wiping down things with alcohol or disinfectant and sometimes fogging. And these generally address what we call indirect transmission. When people were in the room, they might have expelled particles. We can sanitize those areas by wiping them down. Unfortunately, this is not a continuous process. Kailangan gawin ito pagmakalis na yung mga tao. Now, there's another way to sterilize becoming more prevalent. For example, the ultraviolet germicidal radiation. Shown here are photos of UV radiation. This is an LRT where the UP College of Engineering actually partnered with them to provide disinfection protocols and devices. And these help to stay again against indirect transmission. Now, I've also seen some devices where in UV po, I install, let's say, in the air conditioning. And they also, therefore, tried to cut down on airborne transmission by killing the viruses in the air. Now, there are different devices available in the market and they have to be carefully selected. When you ultraviolet, there are specific doses that will actually kill the virus and even specific types. There's UVA, UVB, UVC and the most effective and most practical is UVC. But you also have to take note that there are certain durations on how much radiation and how long you expose a surface to for it to be properly sanitized. And that's just for the virus. There is some risk to the person. For example, UV tends to produce ozone, which is bad at the health. And if the light actually hits the person, there is there is a risk to that particular exposure. So I will ask our medical practitioners to focus on that maybe later on today. Now, for real-time interventions, we are more familiar possibly with filtration. Just like our masks, masks in our filters. But for the structured environment, we can put in something like air purifiers where they actually have what we call filters that grab the particles from the air so that they will no longer float around and infect us. And please be aware that not all filters are actually appropriate for the COVID situation. The we see ads about HEPA filters and all that, even the N95, but what do we really need? The World Health Organization and the CDC recommend a rating of at least MIRV 13 or better. That means that it's at least 95% effective in capturing particles. But please be aware ng rating ko dapat yan ay based on the 0.3 micron level. Now, microns, yun yung lakipun ng kain ng solo-in. There are some HEPA filters out there claiming to be HEPA filters. But they're actually rated 95% or better but mostly for dust particles where actually just a lot bigger. So hindi silas suitable. So what I would recommend is something even higher than the World Health Organization standard which is a HEPA filter. Yung totoong HEPA filter I would suggest at age 13 na rating which is at 99.95% na rating. So shown here is actually such an example of a filter that is installed on the ceiling of an office that allows the filtration of the air even while it is being air conditioned. And the one I like to highlight this particular product is because it is a lot bigger and more powerful than other kinds of air purifiers which is properly sized okay to match the room so there's proper selection and it is properly installed so that when you use it it becomes both effective and economical okay because we have to be practical about this there no point in buying anything if it's not both okay so moving forward the biggest strategy actually is ventilation now by definition ventilation has three parts here we try to replace the dirty air in the room by what we call brain in of outdoor which in general we perceive as fresh cleaner air and to do that we open windows and doors because new or fresh air is coming in we remove the virus laden air fresh air in and contaminated air out of course this implies na meron po tayong in and out yan so meron tayong isang let's say pintana na papapasukan ng fresh air and maybe another door to let out and if it's in a large room it helps if there are fans and ducks to assist the flow of air where by doing the replacement of room air and removing the virus laden air ang end goal punatan is to lower the overall concentration of virus containing particles in the air we want to remove the ones that are recirculating or floating around so I'll show you just a video here where these are particles floating around but by the simple act of opening a window in as little as a minute evacuated tapu lahat ganoon lang po kasi hindi and there are for large rooms we can suggest for example fans, blowers or filters and we recommend a particular number which we call the number of air changes per hour and the CDC and ASHRAE engineering association for for air condition controls recommends at least 6 to 15 air changes per hour to replace 99% of air in about an hour so in 6 is a general number po but I have seen where for clean rooms, for hospitals where it can go all the way up to 15 so wag lang po sana tayo bababa na 6 now you might think gano ba kahirap yung 6 changes per hour in fact it's it isn't it, tipong I will show examples later where a simple electric fan can actually replace the location can actually suffice now let's start with what many of us are exposed to for example our offices and our let's say maybe hospitals where the first scenario on the left we have an air conditioner most air conditioners in the Philippines are split types so it actually siya connected outside to suck in fresh air so pag sarado po yung windows and doors natin naging re-circulate lang po yung your infected air and default assumption kasi natin dito is there is somebody possibly sick or carrying the virus in the room and we do not know so we try as much as possible to avoid that re-circulation so we try to put in fresh air so scenario number 2 is we open windows and doors so that we call it dilution of the air inside using clean air from the outside and a natural air flow will come from the air outside the window at lalabas po sa doors natin it will help of course kumera po tayong exos fans now in our offices definitely there are bathrooms nearby and almost always there are exos fans there they will help so there are simple measures to to address or to minimize infections via airborne transmission now the important keyword is minimization because we can only go so far in reducing the risk now for a non air conditioned environment we have here the the say the household so we can leave the doors and windows open try to partially lampo and naturally there will become there will be currents the important ay may in and out it will also be better kumera po tayong exos fans to help evacuate the contaminated air and if extra fans to improve the circulation of air from the outside and avoid pockets of stagnant air forming indoors now medyo maraming gray air is upag ating sa fans kasi ang typical practice po natin is pag mainit itapat natin in electric fans atin so we cannot be sure if the air that is reaching our phases is coming from an infected person okay so there is some compromise possibly in what the comfort that we are used to however we there are slight adjustments lang po now we don't necessarily need large currents and preferably currents are going from what we call clean air kumera po tayong ceiling fans there are kind of check your models na ceiling fanin niya kumpedin na invest na pababa yung bugan ng hangin it actually sucks air upwards so that if there are infected people down below the fan it actually removes contaminated air from them and is sent out hopefully to the open windows and doors okay na take note na meron po tayong case to case basis dito which we will be we can try to address later on in our discussions now the important thing with ventilation is not just bringing air in and evacuating it because it will take some time to do that with ventilation the biggest portion there is the direction as well especially in big rooms we try to do what we call the an air movement flowing from a clean to a less clean direction an example po yan outdoor air is generally accepted to be cleaner compared to let's say air na na dumahan na sa topat ng isang office mate mo we wouldn't know who is infected or not so in summer we need to minimize the potential to create air patterns na will directly flow across one person onto another and of course that implies we try to avoid recirculation so the photos here are actually different scenarios the one on the top right is where for example two people are in a small room with a window and a door that is open this is actually coming from a recent study by professor Ken Fernandez and Dr. Maynard Berana in the mechanical engineering department where they actually evaluated the effects of the placement of a simple electric fan kung nasabintana ba o nasapinto kung pabuga ba o pahigop yung electric fan and how much air does it actually bring into the room and how much air is brought out an important part of their study shows also about yung particles that are circulated in the air okay so this picture was shown na there is a huge risk parin dalaga if your people are laid out in a certain scenario where in the same direction of flow sila sa hangin okay yung layout nila ganan din sa baba okay yung sa bottom left na photo you have a classroom na ka social distance po sila okay but in the case where it's just one window that's open sinadi kong aka nina magbukas tayo ng pintana di ba one pero kulub naman pa din walang paglalabasan if there's somebody in the room na may suck it in this case the one in the front of the classroom his dark red contaminated air will continue to recirculate which is bad okay kasi madadapuan yung mga ka-klasa nya now the other study on the right where this is for a restaurant where you properly you properly locate the doctor yung bugapon ng aircon at saka yung higup ng aircon so that the pockets of air are isolated to those people lang at hindi kakala sa kabilang tables ang maganda example nga nabanggit kanina doi our previous discussions yung sa yung sa mga Korean restaurants na meron tayo exhaust time in the middle that's actually a good example of if you notice much isolated actually shana air air flow now similar slide but the one on the bottom left is actually something applicable to buses and public transportation where the agreed strategy actually recommendations for buses is that you have the the air from the air conditioner yung malamig po na hangin ay mga galing sa taas pero rather than higupin siya in general sa likod dapat maglagay sana ng mga exhaust thens sa paanan ng mga mga pasahero para isolated po yung hangin sa kanila lang at hindi makcross sa mga ibang pasahero so direction of air flow is critical in these studies now there are so many scenarios actually di pang we cannot spend in to list out all of these scenarios and recommend so meron mga common strategies they know that they are on a case-to-case basis for example for non-air conditioned offices and rick stations I did mention that to open the door and window on opposite sides if there are a lot of windows it is recommended to try to relay out those workstations to be beside the windows para yung da da po sa inyong na hangin ay malinis if it's even possible to put let's say exhaust fans or ducts behind that person so from the window to the person to the exhaust maganda yan okay so higup ka agad at hindi na pupunta sa ibang mga office needs yan now this number for item here is a bit counter intuitive we normally we only see barriers yung mga acrylic barriers that impede yung droplets yung big droplets natin let's say from direct contact yung direct expulsion of droplets into our faces that's fine however please aware that these barriers can actually impede air flow so pwede yung makakaran ng increasing concentration of viruses in one particular area stagnant po yung air hindi hindi gumagalaw and those pockets should actually be evacuated dapat may higup palabas yung so may give and take po may pros and cons po with barriers now of course anam naman natin na meron tay infected people the common sense there is we should place them downstream of the air flow yung figures on the right the top the middle right shows the same study and gleaned are actually the numbers taken from such a study where what will happen if you put an electric fan in different places and this is just a standard electric fan and the air changes per hour sabi ko as 6 nga lang ang minimun natin diba but their studies found that if properly located at either the door or the window you can have as much as 59 air changes per hour and depending on the location as well pagkonti anaman yung so from a for a my recommendation for example is to have the air diluted so that less particles are recirculated but of course it is really the best to have both what you call a push and pull scenario meaning may papasok ko na hangin and may palabas na hangin now if we have air conditioned offices there's always that argument na kung buksal ko natin yung bintana at laka mga pinto lalabas yung malamig na hangin lalakpat at asin koriante natin I have to admit that that is a small price debate koriante natin compared to the health of our employees so it is still recommended na kaya buksa nilang kaya ponte yung windows na if in the case where yung know na hindi talaga kaya there are some offices there na takabalk down yung mga bintana we try to consider filters just like the one here that may preferably multiple ducted inlets where you can have hoses na in certain clusters similar kong ay yung example kung ay yung sa hina nilang ko yun if it's possible you can try to lay out your workstations in a single ring clustered around an exhaust or filter so kahit makaharapman sila kung meron mga droplets na ma release yung tao imbes na abot doon sa kabilang employee ay higupin na kaagad ng filter but take note that kilangan malakas din yung filter natin hindi yung basta-basta lang na mga balilit na filters na na ikita natin pang USB lang kasi they have to be properly sized because if the air around you is not entirely clean it is still possible that these filters will actually produce air currents that will bring dirty air to you so sizing of the filter is very critical even the undersizing of a filter and bringing it close to you might actually produce bad effects so again sizing is important itin atalgo natin air changes per hour in terms of cost these are the initial costs so technically wala naman dapat cost sa pagpukas ng bintana or even up-opening vents a slightly higher cost will be implementing or using fans to increase the effectiveness of windows and reposition them to create directional airflow there was one application before where there was one particular smokey room and our colleagues were thinking how do we quickly remove smoke from that room where it's like the room is inside a building where there's only one door and our recommendation was well sa jayin na merong papasok talaga na forced na hangin and then meron isa pang fan that actually sucks air out so fans are relatively inexpensive na a medium cost is to add filtration systems and in general they can be used to actually supplement the capacities of air conditioners natin that we normally because we think that our air conditioners can provide the airflow that we need to be honest no, okay at it's an exception where most air conditioners do not let in fresh air even if they do the fresh air that comes from those tiny holes in those air conditioners like the window types are not sufficient to produce the 6 air changes per hour adding a filter that's property size can actually improve Closter A1 is adding UV. Now, these are of course the initial costs but you might have to just balance these initial interventions for both the initial cost and the operating cost to provide the most economical and effective way of controlling the transmission of the virus. Marami po talagang mga measures dyan and we would like to invite akit of participants to discuss with us, panelists, so that we can provide further insights. But at least, thank you very much and stay safe. Thank you everybody. We hope that you learned as much as we did from that excellent presentation. We also hope that you will join us every Friday from 12 noon to 2 pm Manila time on Zoom, Facebook, or YouTube. So stay safe, stay connected, and see you online.