Ventilation & Filtration: Prevent COVID 19 + Optimize Health (Air purifiers, HEPA filters)

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    “We’re an indoor species. We spend 90 percent of our time indoors. The indoor environment is just having this massive, massive impact on our health.”


    Joseph Allen from the Harvard School of Public Health is an expert in healthy buildings and recently spoke with MedCram Co-Founder and Producer, Kyle Allred, about the importance of ventilation and filtration in COVID-19 prevention


    Professor Allen is the Director of Harvard’s Healthy Buildings Program and describes how air circulation in our homes, schools, and workplaces contributes to disease, diminished cognitive function, and increased risk for COVID-19. From simply opening a window to upgrading the filters for the heater in your home or office, his advice is practical, affordable, and backed by science. 


    In addition, this conversation covers tips to optimize masks, toxic chemicals in household products (and why “BPA free” does not protect us), and “sick building syndrome.” 


    Watch the full video here, or read the transcript below. 


    Read Professor Allen’s full bio here, and read more of his work on Healthy Buildings at



    Ventilation, Filtration, and COVID-19

    Professor Joseph Allen, DSc, MPH: We’re an indoor species. We spend 90 percent of our time indoors. The indoor environment is just having this massive, massive impact on our health. We’ve done past work showing that ventilation not only helps in terms of infectious disease, this virus and others, but also it has many benefits, and one is better cognitive function performance. But fewer people, even to this day, are thinking about ventilation and filtration in their homes, offices, schools, wherever. We know how to keep kids and adults safe in school. It should absolutely shock you, because there’s an assumption that the products we buy are safe. But what happens is, they often replace the toxic chemical with a chemical cousin that’s just as toxic, and we call this “chemical whack-a-mole.”


    Kyle Allred, MedCram Co-Founder & Producer: Welcome. I’m here with Professor Joe Allen from the Harvard School of Public Health, and if you’re interested in practical ways that you can improve your home, your workplace and our schools, not only from a COVID-19 transmission standpoint, but as places that can improve your overall health and mental performance, there may be no better person to talk with than Professor Allen. He’s co-author of a book called “Healthy Buildings,” and he’s published over 70 different articles in peer-reviewed journals, including some excellent research on COVID-19. And, Professor, since I started following your work a few months ago, I made a variety of changes to my home, to my workplace, even some of the products I buy, so I’m really excited for our viewers to meet you and learn from you, and thanks so much for making time for this.


    Professor Allen: Yeah, it’s great to be here. And that’s quite a compliment. I mean, we really work hard to take the science and translate it into actionable tips for people, so that’s really rewarding to hear you’ve actually taken it and made some changes.


    Kyle: Definitely. And we’ll start with some COVID-19 questions, and then we can hopefully get into just healthy buildings in general at the end. But I want to start with something that everyone’s familiar with now, and that’s plexiglass or barriers similar to plexiglass. We see them in stores, we see them in workplaces. How effective are these? Can they give a false sense of security? And are there even times when they may do more harm than good?


    Professor Allen: Yeah, I mean, the short answer is plexiglass is not the answer. And really, to understand why, let’s just think about how this virus is transmitted. So, coming from respiratory aerosols, right? And these are smaller particles that float through the air. So if you have a plexiglass divider, that might capture ballistic droplets, you know, like droplets you can even see. But most of what you emit when you’re just breathing or talking are finer aerosols that travel right around plexiglass. So plexiglass isn’t doing much, and actually, it can interfere with good airflow in a room. So, counterintuitively, it actually could be doing more harm than good. That said, I want a caveat, there are some places I think plexiglass is a good idea. If you think about a checkout line with a cashier. Many people are coming across that person. I think that’s OK to put that there. Kind of static locations where you’re trying to protect the worker just a bit more.


    Office Building Best Practices

    Kyle: If I’m in an office building and I have, let’s say, plexiglass up six feet high, and I’m spaced at least six feet away from my coworkers, still a good idea to wear a mask indoors?


    Professor Allen: Yeah, absolutely. Because, for the same reasons, if you’re in a room and you’re with coworkers and you’re spaced, that’s good. The amount, or how much, the aerosol’s built up indoors would be a function of how much is emitted from an infectious person and how well the ventilation system is working. And so masks are the single-most important intervention, because you’re limiting the emissions or how much is coming out. Even a simple mask could get you 60, 70 percent removal efficiency. So this is the most important intervention we can do, and I don’t see masks going away any time soon, certainly not until we get through this next surge, whatever this new variant brings us, and until many, many, a large percentage of people, are vaccinated.


    Kyle: We’ve all heard so much about washing hands, masks, distancing. Why do you think there’s been so little discussion about ventilation, especially up until recently when the CDC finally revised their guidelines to include ventilation strategies as part of their recommendations. Do you think ventilation is as important as those other three pillars, if you will?


    Professor Allen: Yeah, there’s no question, and it has been such a disappointment, and quite honestly it’s been so utterly confusing to me why the CDC, World Health Organization, many others, have not acknowledged airborne transmission, which then sets up buildings and ventilation as a control measure, so it doesn’t make sense to talk about ventilation and filtration unless you acknowledge airborne transmission is happening. 


    We’re coming up on a year since I wrote my first piece and published it, talking about healthy buildings as the first line of defense against this novel coronavirus, and in that piece, I said, there’s things we don’t know and we don’t know for sure, but certainly we know enough to know that we need to act and that airborne transmission was likely. And that means, we need more outdoor air and better filters. And so this is, I think I have 25 or 26 op-eds since last February, and in every one, even though I’m talking about different topics — airplanes, schools — I’m always talking about ventilation. Fundamentally, it’s the same thing. 


    So it’s been really frustrating, I think for everyone in my field who studies this, that CDC would not acknowledge that airborne transmission was happening. The evidence is just airtight. We could talk about the basics of aerosol physics; we could talk about air sampling data; we could talk about the epidemiology and high-profile case studies. Everything points to airborne transmission. We knew this in February last year, and every piece of evidence has further supported it. And that’s a problem for the exact reason you said, that many people have gotten a handle on the control measures. OK, I have to wash my hands, distance is good, hopefully people are wearing their masks. But fewer people, even to this day, are thinking about ventilation and filtration in their homes, offices, schools, wherever. 


    Three Steps For Clean Air at Home

    Kyle: What are some practical things people could do today or tomorrow in their home or their office or their school to make it safer from a ventilation and filtration standpoint? 


    Professor Allen: Yeah, it’s actually quite easy, and I’m not oversimplifying it. But the way we talk about it are really three steps. Think about it this way: first, you want to increase the amount of outdoor air coming in. So if you’re in a home, like I am, that means opening up the windows even an inch or two. It’s cold outside where I am, but an inch or two really helps. If you’re in a place with a mechanical ventilation system, you want to open up the outdoor dampers, bring in more outdoor air, because typically a building doesn’t bring in enough. It’s a bare minimum. You want to go above those bare minimums. So that’s number one. Same applies to the car, for example. Roll down your windows, bring in more outdoor air. Number one. 


    Two: any air that’s recirculated, you want to run through a higher efficiency filter. So maybe not everybody recognizes that in, say, a commercial office building with a mechanical system, some fraction of the air’s from outside, but a lot of the air is recirculated. 


    And we don’t just want to be recirculating virus-polluted air, of course, so you want to use what’s called a MERV 13 filter, M-E-R-V 13, or higher. That’s a filter that captures about 80 percent of the particle sizes that we’re interested in for this virus. Number three: if you can’t achieve what you need, in terms of protection, with those two, you want to use portable air cleaners with a HEPA filter. This is a simple device. You can get it at your local hardware store even. Plug and play. 


    We built a tool at my Harvard Healthy Buildings Program website with Shelly Miller at UC-Boulder, that lets you calculate what size device you would need in your room based on the room size. So really, three things: more outdoor air. better filter; on recirculated air; if you can’t achieve it, use a portable air cleaner with a HEPA filter. It’s really that simple. 


    Kyle: I was looking at a chart earlier today that showed the average air changes per hour that a home or office building or school should try to achieve, and I think it was over six air changers per hour is optimal. I heard an interview with you recently where you mentioned that the average home in the United States has about 1/2 of an air change per hour, dramatically less than what’s optimal. Why do you think homes and office buildings are so terrible with ventilation? 


    Professor Allen: The answer is, we don’t design buildings for people, and that’s shocking. Said better, we don’t design it for people’s health, right? We design for these bare minimums, largely driven by energy efficiency, which is critically important, but often at the expense of health. And, you know, it was about the time in the 70s we started tightening up our building envelopes to save energy in response to the energy crisis, and it ushered in the era of sick buildings and the term “sick building syndrome” first appeared shortly after that. 


    Now, we’ve all spent time in these under-ventilated spaces. You might describe it as “stuffy” or “stale,” or you’re in a conference room and you can’t concentrate, and the door opens and it literally breathes life back into the room. And so, in all of the spaces we spend our time, people will be surprised, we get very low ventilation rates. So half an air change per hour means about half the volume in the air of your house is being changed out. And new condominiums that are super airtight can be 0.1 air changes per hour, so really little exchange happening. Schools should be, if they’re meeting code, three air changes per hour, but most of them only get 1.5. 


    So, we have many places that aren’t even meeting the minimum standards, let alone a healthy standard, and it’s a real problem.


    Air Purifiers

    Kyle: I want to ask you a little bit more about portable air purifiers. I have two in my home, and I think they might be good examples that people can learn from and learn from my mistakes. One of them, I bought years ago. It’s not a HEPA filter, but it has some kind of fancy features; it’s got a UV option that you can turn on; it’s got an ionization option. Are these effective at stopping transmission of viruses like the SARS-CoV-2 virus, and are they necessary?


    Professor Allen: Yeah, so first thing I’ll say, then I’ll answer your question is if you’re looking for a portable air cleaner, look for a HEPA filter and nothing else. You don’t want any of these bells and whistles. But I’ll answer your question directly, because it was different. Can UV inactivate a virus? Sure, absolutely. Do you need it in a portable air cleaner that’s in your house or your office? Absolutely not. You’re probably paying more for it, and the reason you don’t need it is because all you need is a good fan in your portable air cleaner, blowing air against a HEPA filter, which captures nearly all airborne particles. 


    So you don’t need any of those bells and whistles, and you have to be careful if you use something like ionization, in particular, because they can generate ozone, which is a respiratory hazard and you’d be putting that right into your breathing zone. They can generate formaldehyde, which is another respiratory hazard, and they can also generate ultra-fine particles, which is another respiratory hazard. 


    So you want to be careful that we’re not solving one problem and creating others, and importantly, there’s something else that’s actually less expensive that will do the job the same or even better. So, for those reasons, you need to avoid ionization and UV in a portable air cleaner. Just look for a good HEPA filter with what’s called a good clean air delivery rate. And I can talk about that more if you’re interested. 


    Kyle: Yeah, I am, because I got a HEPA filter this summer, because of the forest fires here in Oregon were so bad, and I heard you mention that clean air delivery rate, and mine is well below that. I think mine is 150. So, yeah, could you explain what that is and what number you should look for? 


    Professor Allen: Yeah, and that’s interesting you bought it for the wildfires. That’s a great idea, because the mechanics are the same. And I’ll talk about clean air delivery in a second. All you’re doing is removing particles from the air, be it from smoke, wildfires or cigarette smoke or respiratory aerosols. You’re just capturing these particles, so that’s the basics. The clean air delivery rate is something you can find on most air cleaners, where they actually measure this. And it’s a combination of how much air moves across a filter and how good that filter is. 


    So you can imagine, you have the world’s best filter and a poor fan, and it should have a low clean air delivery rate; it’s not that good, even if it has a good filter. The opposite could be true. You could have a fan that’s super powerful, moving a lot of air but a terrible filter. That’s not gonna do much good. 


    Clean Air Delivery Rate

    So the clean air delivery rate is something that combines both factors. The clean air delivery rate is in units of CFM, cubic feet per minute. So if you took the CADR, clear air delivery rate, on a box from one of these manufacturers, you could estimate how many air changes per hour you’d get from your room. And the formula is super simple. Clean air delivery rates, let’s take that 300. 300 CFM times 60, so now it’s 300 feet per hour, divided by the volume of the room, length times width times height. So if you had a 300 CADR in a 500 square-foot room with 8-foot ceilings, you’re gonna get over four air changes per hour; it’s gonna be 4.5 air changes per hour. 


    So the calculation’s pretty simple, and our team has recommended for small volume spaces trying to get 4-6 air changes per hour. And remember, the typical home is half an air change per hour, so it’s 10 times higher than that. So it becomes really easy to then find a portable air cleaner that’s the right size for your room, and if that all sounded too much or you didn’t follow it, we have a tool on our website that you just put in the size of your room and it lets you know what to look for in terms of the clean air delivery rate for a portable air cleaner.


    Kyle: Thanks a lot. Yeah, we’ll definitely link to that. And some of these HEPA filters, I mean, they’re not that expensive, right? You can get some around $200 or less?


    Professor Allen: Yeah, that’s right. I mean, you could find one for a lot more than that that has all the bells and whistles, sensors and all these things, but if you want a basic one, and that’s all you need really. You turn it on, it’s got a good CADR, look for a clean air delivery rate over 300, um, yeah it’ll be about two or three hundred dollars, and that’ll be great for a room of that size. 


    Face Masks & COVID-19

    Kyle: You and your team have done a lot of research and had commentary on masks, and I was in the situation about a month ago of wanting to buy some new masks, because ones I had early on in the pandemic were two-layered masks and they didn’t fit all that well. So can you walk through some tips? I know everyone has heard a lot about masks, but it still can be a daunting process to figure out exactly what mask to actually purchase. Can you go through some tips on really optimizing masks?


    Professor Allen: Yeah, and I feel for people. It is confusing out there, and at this point in the pandemic, it shouldn’t be confusing and we should be well beyond the “anything goes” period of the mask. That said, I’ll talk about masks in terms of low risk activities — going for a walk and maybe you’re going to pass by someone and stay distanced. Any old mask, I think that’s good. You have a cloth mask, simple cloth mask, fine. Going to the grocery store, you’re gonna want something a bit better, and certainly if you’re in an occupation where you’re around a lot of people, you’re going to want something that’s even more efficient. 


    But here’s the basics, right? It’s a function of the filter efficiency and the fit, and that makes sense, right? You want something that’s going to capture a lot of the particles coming out, but it also has to fit on your face pretty well, or else, instead of going through the filter, it’s just going to come out through the sides or through the top. And so, we recommend two or three layer masks, because they have high efficiency, or pretty good efficiency, like a good surgical mask, a blue surgical mask. 


    If you want something that’s more efficient, you could go to the N95, which are hard to get and there are some shortages still in healthcare, unbelievably at this point. Something that’s called a KN95, but I can mention to be careful there, because there have been counterfeit KN95s on the market. And the N95 stands for 95% efficient. 


    But there is a way to get close to N95 with just materials that you probably have access to right now. And so a colleague of mine, Linsey Marr, put out a paper with a colleague of hers, where they showed that a simple surgical mask with a cloth mask over it gave you over 91% efficiency. And really what that cloth mask is doing is helping with that fit. So you’ve maybe seen blue surgical masks and some gaps on the side. Well, if you put a mask on top of that, now you’re really forcing that air through those filters. 


    But here’s the most important thing about masks. It’s less about the individual removal efficiency and more about the combined benefit. So when everybody wears a mask, particles have to go through two filters. So even if I have a 70% percent efficient mask and you have a 70% efficient mask, the combined efficacy is 91%. Add in spacing between us, put in ventilation and filtration, and you can quickly get to exposure reductions of 99% or more. So this is where the power of universal masking comes in, even if people have imperfect masks or they’re not fit exactly right. It’s the combined benefit that’s what’s providing the big benefit for everybody. 


    Kyle: And in a high risk environment, that’s really interesting about wearing a cloth mask over top of a surgical mask. I’ve also heard come discussion about inexpensive mask fitters, so like a piece of rubber that can go around the mask to help achieve a better fit. Do you have any familiarity with those?


    Professor Allen: So I’ve seen them. I haven’t tested them or actually haven’t looked at the data, but the logic of it makes a lot of sense. I’ve seen people do all sorts of simple tips like that in trying to improve the fit, even with the loops in the back, tying them tighter or cross-stitching them. And the idea, right, is that’s all you’re trying to do: make sure it goes over the bridge of the nose, it’s flush against the face, and comes around your chin. 


    And so if you have a loose mask, that’s not going to help that much, so any kind of face mask fitting, or even something that can tie and tighten it is gonna provide a big benefit. And the way to think about that, if you think about an N95 mask, which is technically a half-face respirator, if you were given one of those if you worked in a hospital, and you were given one of those, you would have to go through what’s called “fit testing.” And the idea of fit testing is to be sure that the fit is good. So we know fit matters; in fact, there’s all sorts of regulations around fit testing, but to the average person, you just want to make sure you can get by with a regular mask that’s sealed pretty well, or do some of these other tricks to improve the fit.


    Humidity & COVID-19

    Kyle: So we’ve talked about masks, we’ve talked about ventilation a bit, what about humidity? Does humidity play a big role in transmission and should we consider humidifying our homes?


    Professor Allen: Yeah, humidity, it’s interesting. I wrote about this in the first couple pieces I wrote last winter, and then I stopped writing about it through the spring and summer, I think for obvious reasons. And then colleagues and I wrote about it again in November. Humidity’s important, but I put it as a “nice to have,” not a “must have.” Maybe I’ll talk about the “what’s happening” and why, and why I think it’s challenging for buildings. 


    So it’s probably helping in two different ways at least, maybe three. First is our respiratory system. So, in our lungs, we have what’s called a mucociliary escalator or mucociliary clearance, and that’s the cells of our lungs are lined with cilia and they’re all beating, right. Anything we breathe in, many of the particles are captured in the mucus and the cilia bring it up and we swallow it harmlessly. Great defense mechanism, cleans out our lungs. Low humidity, and here I’m talking about 20 percent humidity, actually the beating of the cilia, a colleague of ours just showed this beautifully animated, that it’s less efficient. You have less clearance. So your immune system, or your, should say, respiratory system’s, defenses function better at humidity in the 40-60% relative humidity range. Not a problem in the summer, but in the winter when the humidity gets down to 20%, 30%, it’s not ideal. 


    Second in other ways, it’s influencing transmission, so when it’s less humid, the virus survives better, which is maybe counterintuitive to some people. So the virus survivability is less at 40-60% relative humidity. And last, it also may influence how quickly droplets evaporate and how long they can stay aloft. So for a few reasons, it can influence disease transmission and also host susceptibility. The problem, and why I think it’s a “nice to have,” not a “must have,” is that most buildings can’t do anything about it. 


    If you have a mechanical system, it’s really hard to retrofit or any time you’re adding water into a building it gets very tricky. But your question at the beginning, right, if you’re home, sure. If you have a portable humidifier, my team, we’ve had papers maybe 10 years ago modeling the humidity inside homes and influenza transmission. And yeah, you can bring up the humidity into that 40-60% relative humidity sweet spot through a portable humidifier.


    Kyle: You mentioned car travel early and how just cracking a window in a car can make it significantly safer from a transmission standpoint. How about air travel? How safe do you think air travel is and what are some of the most high-risk parts of air travel?


    Professor Allen: Yeah, so I’ll do a little credentialing, unfortunately, just to establish that I’ve done work not just on buildings but on airplanes for over 10 years. In 2013, I was one of the lead authors of a National Academies report on infectious disease transmission in airports and on airplanes. 


    So I’ve studied this for a long time, and I wrote an op-ed in the Washington Post, maybe it was in May, that seemed to surprise people, because I said, you don’t get sick when you’re on an airplane, really. And that’s because, if you think about what’s happening , these fundamental factors we’re talking about — ventilation and filtration — when you’re on an airplane, the ventilation’s actually quite good. So you get 10 or 20 air changes per hour. Recall the home is about half an air change, and our target was 4-6. Hospitals will target 6 air changes, except for the most extreme and then they’ll target 12 air changes. So an airplane, you’re getting a lot of air. 


    Second, all of that recirculated air, remember I said in buildings we’d like a MERV 13; that gets about 80%. Well an airplane, everything that’s recirculated goes through a HEPA filter. That’s 99.97%. So it turns out, when you’re on an airplane and the systems are running, it’s probably one of the lowest risk times during the whole travel experience. Now, add on masks on top of that, which is an excellent idea, and the risk gets even lower. Now, that’s not to say it can’t happen. Can transmission happen? Yeah, transmission can happen anywhere. It’s just lower risk than most people think, and we have millions and millions of passengers, even to date, and we have a handful of cases that are suspected — and I’m not even sure all of them are accurate — a handful of cases or instances of transmission on an airplane. 


    That said, there are areas during travel that I think are important. We know restaurants are higher risk. Well, when you’re in an airport, lots of opportunities to sit at a restaurant, at a bar, masks come off. So I think those are higher risk. Also, during boarding on an airplane, we warned in our 2013 report that airplanes do not always have the ventilation systems running while people are boarding. That’s a mistake. And I hope — I called this out in the op-ed in May and we’ve been talking about it ever since — airlines have to have ventilation on when the plane’s at the gate. Otherwise, you are cramming a lot of people into a small volume space. When the systems are running, the ventilation and filtration are great, but they’re not always running. 


    CO2 Monitors to Air Quality

    Kyle: Speaking of that, you mentioned in a previous discussion how a portable CO2 monitor can be a way to measure, kind of a surrogate to measure air quality, and it made me think of it with airplanes, if the engine’s not running and you have one of those, could the CO2 levels raise to unacceptable levels? And is this something that people should consider for their workplace if they’re concerned about ventilation issues?


    Professor Allen: Yeah, I mean the reason we know that airplane ventilation can be poor during boarding is because we’ve measured it. I published a paper a couple years ago looking at CO2 concentrations during the whole flight, including boarding, and we see CO2 concentrations sometimes over 2500 parts per million at boarding. Now for reference, if you’re meeting a minimum standard, it’s gonna be under 1000. And so I’m with you, I’ve got one right here on my desk, too, right? So I’m over 1000 parts per million. I should open up my door, get some cross ventilation going in here. That’s too high. But, you know, the other side of this, I’m in my own home with my family, I would never have somebody over here right now with these conditions. If had somebody in here, which I wouldn’t, I’d have a mask on, windows open, I’d have my air purifier going. 


    So, I think these things are gaining traction because the other controls we have, people can assess. I can tell if you’re wearing a mask, you see hand washing, you see distancing. But you can’t tell if the air is clean, so this is a way to kind of get a sense of a space, right. You have no idea what’s happening in my office, unless I did this. I wouldn’t know. The challenge with CO2 monitoring… So first, CO2, if you’re not familiar with it, is a proxy for ventilation, where the main source of CO2 indoors, if you’re well ventilated, CO2 would be low, and vice versa. 


    The problem, though, is that there are two really main mechanisms for controlling this virus indoors in the air. It’s ventilation or filtration. So ventilation will change the CO2 concentrations, but filtration won’t. So said better, I could be in this office with my air purifier going with my HEPA filter, have a thousand parts per million of CO2, which isn’t good from a ventilation standpoint, but be totally fine because the filter is working. So you have to be careful with CO2; it’s only covering half of the control measures indoors. 


    Kyle: Interesting. And I’ve heard you also speak about how when ventilation drops and potentially CO2 levels rise indoors, cognitive performance can suffer as well. Tell us more about that. I thought that was very interesting.


    Professor Allen: Yeah, I mean, right now, we’re thinking about half of health, which is disease avoidance, and rightly so, but here’s a whole other aspect of health, right? It’s flourishing, it’s wellbeing, it’s the positive aspects of health and feeling well. And so we’ve done past work showing that ventilation not only helps in terms of infectious disease, this virus and others, but also it has many benefits and one is better cognitive function performance. 


    So we’ve done studies, we use people in a really controlled office environment, where we have them do their normal work routine, we administered these complex cognitive function tests, and while they’re in the room, we change the air they’re breathing. We change the CO2 levels, we change ventilation without them knowing. It’s a guinea pig type of scenario. It’s a double-blinded study, and what we find is that when people are in these environments with better air quality, low CO2, they perform significantly better on these tasks of higher-order cognitive function in domains like strategic decision making, information usage, crisis response, things that are really relevant to everyday functioning but also the types of work we all do every day. And I think that’s surprising to people, that study surprised people because we didn’t test anything exotic. We just changed the levels slightly indoors to levels that most buildings could attain. And we went above the bare minimums that are required. And when you do that, our study and many others now. There’s decades of research showing the benefits of going beyond these kind of code minimum standards that we set in buildings, beyond infectious disease benefits. 


    Designing Healthy Buildings

    Kyle: Beyond ventilation, are there any other design changes that you think can contribute to a healthy building and better performance, better work performance or school performance for kids? 


    Professor Allen: Yeah, I mean, so we released — so there’s a lot of things. And right now, the world, rightly so, is thinking about ventilation, air quality, filtration, humidity. But we released a couple years ago called “The Nine Foundations of a Healthy Building,” and it was in response to questions just like you asked, where people say, “well, what else matters?” We realize that, despite all this great research, not a lot had been hitting the mark in terms of the people who were designing and operating buildings. 


    So we released this report, “The Nine Foundations of a Healthy Building,” where we talk about air quality, water quality, lighting and views, or biophilic design, acoustic performance, thermal conditions, dust and pests, safety and security. You know, all of these factors that really have a deep scientific body of literature behind them, supporting them and showing how each one is associated with sometimes better cognitive function, reduced “sick building” symptoms, some of these are associated with reduction in asthma. So, there is a really rich body of scientific knowledge out there on all the ways that a building influences our health.


    Kyle: And speaking of buildings influencing our health and ways to make them safer, you’ve been a big advocate for getting kids back to school for in-person learning, and that it can be done safely for both teachers and students. What is the landscape right now in the United States for in-person learning, and what are some of the consequences of kids not being in school for in-person learning? 


    Getting Kids Back in School

    Professor Allen: Yeah, I’ve been saying this is a national emergency. It’s been a national emergency since we first closed schools, and I don’t think it’s been treated as such. And it’s something that I’m working 24/7, 7 days a week. I can’t stop thinking about this topic, trying to think, “what else can we do?” What other tools can we put out there to help schools get back, because it is so concerning what’s happening. 


    The costs are enormous with kids out of school. This included virtual dropouts. We knew it from the spring, right, in Boston where I was, 10,000 — 10,000 — high school students unaccounted for in May. We’ve seen impacts –actually, the virtual dropout issue has persisted. A report from 60 Minutes just a week ago. Hundreds of thousands of kids missing in the system. Totally missing. And talking about how schools are really our first effort to detect issues with kids or find out why are they out? Are they having problems at home? 


    UNICEF reports kids are out of school, greater risk of exploitation, abuse, neglect, violence. There’s food security issues. I wrote an op-ed with a colleague of mine, Dr. Sara Bleich, talking about a billion missed school meals in the spring alone from schools closed — a billion missed meals. And this has continued now, and we’re coming up on a year of schools closed. We’ve seen decrements, or losses, in learning and we have reports — it’s not one area of the country — we’ve had reports out of Virginia, Los Angeles, in Texas, in Minnesota. We see losses and gains in literacy. 


    This is just the beginning of these impacts. We’re just starting to uncover these. We will see these kinds of reports for months and years, and this is why I call it a national emergency and here’s the flip side of that. We know how to keep kids and adults safe in school. We know that schools are not driving transmission. We had this data in June from studying what was going on in Europe. We had many YMCAs and childcare centers opened in New York through the peak of the spring spike. We had camps open through the summer. We now have data through the fall that schools are not driving this. 


    Transmission through the school looks just like transmission in the community. And when we put in these control measures, like universal masking, ventilation and filtration. We’ve been harping on these since June when my team released this full report. We can keep kids and adults safe. Importantly, these are not just about keeping kids safe. It’s about keeping everyone in the building safe. 


    We do get some advantages with kids. The virus has spared us in now ways except this one, miraculously. The risk of a kid dying from COVID is one in a million. That’s the most recent study in JAMA. They’re about half as likely to get it as adults. So we are getting some benefit; they can transmit it, they can definitely get it, and kids can definitely die, but it is very rare. So we get another benefit when it comes to schools. So weighing those factors to me is absolutely imperative that we get kids back in school safely and that schools put in these mitigation measures we’ve been talking about. And the costs are just so massive, and just so deeply, deeply concerning. It’s why I call it a national emergency, the national emergency. 


    Kyle: And you and your team have put out a PDF with some simple steps that schools can follow to make their environments safer, correct?


    Professor Allen: Yeah, so many resources. So my Harvard Healthy Buildings program is a, and we have a page dedicated to schools, We have a 60-page report and PDF, and also on the website on holistic risk reduction strategies that also talk about the specific of these healthy building measures, the target air changes per hour, ventilation, filtration, tips and tricks for what you can do. 


    We’ve also released a 5-step guide for assessing ventilation. So if you’re not sure what to do in your school or what it looks like, we went out in schools over the summer, on the weekends, were measuring ventilation rates and turned it into a guide that any school can use. We built a tool to help you calculate portable air cleaners, written 7 or 8 op-eds talking about how portable air cleaners can help with a HEPA filter and other strategies. 


    So we put out many of these guidance documents, a white paper on the science around risk reduction and air filtration. So we tried to put out these guides to help schools get back, and we’ve worked with schools. I know there’s an entire state that’s using that report as their strategy. I get calls from really all over the country from different districts that have used that as a template. So there are other guides out there, too, and I just think the important thing is that you do something. I think some schools haven’t put in any control measures, and I think that’s a mistake too. And if they haven’t had cases, I think they’re getting lucky and maybe with the new variant that’s more transmissible, their luck may run out. So it’s absolutely imperative to put in these simple, relatively simple, control measures we’re talking about. 


    Chemical Safety & “Chemical Whack-A-Mole”

    Kyle: I want to ask you about some of the products that we all have in our homes or use every day. And I have a water bottle here that says BPA free on it, and when I read some of your book, when you talk about how some of these chemicals — I think “chemical whack-a-mole” was the term you used. So could you talk a little bit about that? Why something like “BPA free” may not give the security that we hope it would?


    Professor Allen: Yeah, so moving to the topic of chemicals, this is a massive topic that doesn’t get enough attention. It’s something I’ve been studying for a long time, and you’ll really get me going, because there’s a chapter in the middle of our book — I’m not trying to sell a book here — but it talks about our global chemical experiment, and I promise if you read it, it should shock you. It should absolutely shock you, because there’s an assumption that the products we buy are safe and if there was a chemical that’s toxic, well of course it shouldn’t be in your water bottle or my couch or my kids’ car seat.


    But, here’s how it works, and here’s the problem: there are over 80,000 chemicals in commerce, very few have been tested for health and safety. And so, what happens is we don’t follow the precautionary principle. We allow companies to put these chemicals in commerce and if we as scientists find out it’s harmful, they take it out. But what happens is they often replace the toxic chemical with a chemical cousin that’s just as toxic. And we call this “chemical whack-a-mole.” And it’s this never-ending game that’s been played for decades. 


    And BPA is a great example. So if you’re a customer, you’re well-meaning, you look at your bottle and one says “BPA free.” Well, I’ll get the BPA free one. BPA must be bad. Even if you know nothing about BPA, and BPA stands for bisphenol A. It’s a hormone interrupting chemical that’s used in some plastics. The reality is, though, BPA got a bad rap, and so manufacturer’s seized on this and said, “well, I’m gonna sell BPA-free everything.” They didn’t just take out BPA. They took out BPA, but they replaced it with its chemical cousin BPS, for bisphenol S. Sure enough, the toxicological profile looks exactly the same, darn near similar to BPA. So that way, they played a game with you. As a consumer, BPA free is great. That label might as well say, “contains BPS.” BPS is starting to get a bad rap. You know what the replacement is? BPF. 


    This goes on and on. We’ve seen this with pesticides decades ago. We see this “chemical whack-a-mole” in nail polish. We see swapping of chemicals in e-cigarettes. We see this in flame retardants that are in your couch, in my couch. We see this with these “forever chemicals,” these stain repellent chemicals that can cause testicular cancer that you find in nonstick pans that are used on carpets, and there was one that was labeled “bad,” so that was removed and were just subbed in for another one. So this game of chemical whack-a-mole happens all the time and we sometimes call it “regrettable substitution” is the less playful name for it, but it’s another name I don’t like, because it implies, “oh, whoops, we made a mistake. It’s a regrettable substitution. Whoops.” This has been happening for decades. There’s nothing regrettable about it. It’s a knowing failure of the system and a loophole in our chemical policy. 


    And here’s where it’s interesting for all of us and everybody. These chemicals, they migrate out of their products. And if you take something like these forever chemicals, the ones that are in your nonstick pans and in your carpets and are in our clothes — it makes things water and soil, just wash off these days. We love them as consumers. Well, these things are really pernicious. They last in the environment forever. 


    I wrote an op-ed calling them forever chemicals and named them that two or three years ago at this point when that piece came out. But they’re associated with these harmful effects, carcinogenic effects. They’re called “obesigens.” They interfere with lipid metabolism. So we have all of these, you know, known adverse effects. We keep using them, and we have this chemical whack-a-mole, and the problem with these forever chemicals is that at this point 6,000 variants. So what do we even study next, right? So as a consumer we really have no chance to be like a thoughtful consumer and avoid these things, because it’s a totally broken system. 


    Kyle: Any specific recommendations for people to help navigate this system of chemical whack-a-mole and finding products that are safe to use?


    Professor Allen: Yeah, so I think the first thing is all getting informed about this, because I think few people know this is going on. Again, I’m not trying to sell a book here, but you could look up “forever chemicals.” Look up this op-ed on chemical whack-a-mole. If you’re interested, read that chapter. And you’d be really surprised, and then you can start asking for it. 


    I’ll say from a system standpoint, we’re trying to address this through my Healthy Buildings Program at Harvard, with Harvard’s Office for Sustainability. We created the Harvard Healthy Building Materials Academy. And what we’re doing is starting to change buying practices. So instead of a company saying, here’s something that doesn’t have BPA, we’re starting to ask and say, “well, what else is in it? And by the way, we don’t want anything in that whole class of chemicals.” Right, we’re not gonna play this whack-a-mole game. Forever chemicals, we don’t want any of them. I don’t care what your next “safe” replacement is that you tell us is safe that we’ll find out is toxic. And we’re having a lot of success. 


    We have over 40 pilot projects on our campus where we’re showing that you can design these spaces with great products that don’t impact cost or time of your projects, they look great, perform the same, and you don’t have the toxic chemicals in them. So, there’s a way to do it and we’re trying to move that with the market. We partnered with Google two years ago on this initiative. Many other manufacturers, big companies are starting to put their buying power behind this movement to kind of rid the market of these toxic chemicals that are in everything. They’re in our deodorants and shampoos, and I don’t use shampoo; that’s a bad example for me, but in our couches chairs, they’re all around us. So the way to do it is to move upstream and change the whole system.


    Kyle: Well, professor, thanks so much for all of your research and advocacy for this. Before I let you go, any last things that you want to mention before we chat next time?


    Professor Allen: Yeah, I just want to say thanks, and I really appreciate the interview, because it’s rare to touch on COVID, but also talk about all other aspects of healthy building, and then even end on that topic of chemicals, right. So we think about healthy buildings and it’s all of these spaces. And the last thing I’ll say is something I usually start my presentations with, but I think it emphasizes why healthy buildings matter so much. 


    We’re an indoor species. We spend 90 percent of our time indoors, and so it’s obvious, I think, when we think of it that way that the indoor environment is just having this massive impact on our health. But there are ways to do it better. We’ve been in the sick building era, but it doesn’t mean we don’t know how or can’t do it better going forward. Any my hope with a silver lining coming from COVID is now with everybody recognizing just how much the built environment and building influence our health that it leads to a fundamental shift and change in terms of how we prioritize these places where we live, work, play, pray, heal, that we start designing them with a health-first perspective.


    Kyle: Well, we’ll be sure to put links to some of the resources that you mentioned, and thanks again. Really appreciate it, professor. 


    Professor Allen: Yeah, thanks for having me on. I enjoyed it.

    1 Comment

    1. Bruce Peterson on January 23, 2021 at 9:57 am

      Doctor, in Minnesota and many other states the building codes continue to require tighter houses for energy efficiency, but people seem to be getting sicker and having more allergies. Have you studied the effects of these building requirements on health?

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