番茄社区

In this video, Jeremy Faust, MD, editor-in-chief of 番茄社区, discusses the recent with its organizer, Joseph Allen, PhD, and what benefits we can expect from improving our ventilation and filtration in indoor spaces.

The following is a transcript of the conversation:

Faust: Hello, this is Jeremy Faust, editor-in-chief of 番茄社区 and author of .

Today, we're joined by Dr. Joseph Allen. Dr. Allen is director of the Healthy Buildings Program, an associate professor at Harvard's T.H. Chan School of Public Health, and he's just the air quality guru for before and after the COVID pandemic. His book is called . He is the chair of The Lancet COVID-19 Commission Task Force on Safe Work, Safe Schools, and Safe Travel.

Dr. Allen, thanks so much for joining us.

Allen: Yeah, it's great to be with you.

Faust: So the White House, that was the last time we saw each other. That was the first time we met in person, actually, at the White House. Very cool, right? It was for your event, this . How did that come about, and what was your big takeaway from that?

Allen: It was a major event at the White House and I don't think it's overstated when we say it's a landmark event in terms of what this means for buildings and ventilation. I mean, the White House. The White House, right? The biggest bully pulpit in the country thought it was important to have the first ever Summit on Indoor Air Quality.

I've been in this field for a long time. It's a relatively small field; I think I know most of the researchers around the world who are doing this. It's a small group relative to other fields, and to see this at the White House was -- I had to pinch myself, honestly, a couple times.

I think it's a watershed moment because so much of how we operate and design our buildings determines our health, and this message is now breaking through in a big way. And I give credit to Dr. Ashish Jha and his team and the White House Office of Science Technology Policy for really elevating buildings into the national strategy around the COVID response.

Faust: It was interesting to me, being in that room. Of course, I was happy to be invited, but I was actually a little confused, and it was because I'm not an air quality guy.

You look around the room and you meet who's there, and it's a lot of scientists, a lot of researchers, there's a lot of people in the OSHA [Occupational Safety and Health Administration] space or in the technology space, and there were probably three medical doctors in the room -- Ashish Jha, me, and Celine Gounder. I didn't see any other MDs.

We were there to sort of be flies on the wall, and I actually thought that was emblematic. There's still this disconnect between people who were talking about this as a sort of a healthy workspace thing, and then like physicians who prescribe things like physical therapy or we prescribe things like cardiac rehab or medicine, but we don't prescribe things like "open the damn windows." I'm just curious whether the fact that there were just three of us there was sort of emblematic of the problem or just progress that it wasn't zero?

Allen: I take it as progress, and I hope eventually you do write scripts for opening your window.

Here's where I saw this progress: it was a relatively small group, right? Maybe, I don't know, 50 to 70 people, something like that. As I scanned the room, I saw the same thing. I saw a lot of my really trusted indoor air quality colleagues -- Rich Corsi, Linsey Marr, Shelley Miller -- people I just know, and they're really good.

Then I see the MDs, who I know are really good. Then you look around the room and you had representatives from not every agency, but agencies that are critical in this battle: EPA [Environmental Protection Agency], CDC, NIOSH [National Institute for Occupational Safety & Health], Department of Energy, Department of Education.

So you had all the representation from important agencies, and then you had business represented, you had technology and innovation represented, and you had community groups represented, like my friend Carl Howell, who presented about all the work they're doing in Community Teamwork in shelters and things like that.

So, I thought the mix was actually really great. It's also why I think it stood out from other meetings. I've been in a lot of meetings where it's a lot of us indoor air quality scientists saying the same things we always say to the same people -- we say it over and over. Probably, the MDs do the same thing.

This kind of mixing was really important, and I've had great follow-up conversations since. So I took it as a positive in progress. It seemed like out of the 50 to 70 people, whatever it was, in the room, we had a mix of policy, medical, scientific, building science people, community. It was really terrific.

Faust: I'm trying to sort out from that, what is the clinical effect that we might expect to see?

Thanks to you and others, I followed up with some of these people who were in the room -- and actually some of the business groups are really where there's an untapped resource; they don't really study it, but they in a way could -- to get an idea of, if you do what people like Dr. Allen tell us to do, or Lindsey Marr, or whoever else is out there, what will happen to your business? Will you have fewer sick days? Will you have people actually healthier and have better productivity?

I'm really trying to sort this out. I know there's not one answer because there's a million scenarios. But what is the sort of clinical effect that you would anticipate, say, for a school, if they take two schools in a parallel universe with 30 kids in each classroom and one of them has good filters and good ventilation and one doesn't? Take me through a flu season. What difference would the two feel like?

Allen: Well, I think the evidence here is really deep. Whether you look at schools, offices, whatever -- I'll take your school example -- you're going to see these multiple benefits of better ventilation and better filtration on things like you just mentioned.

We see , we see impacts on reading comprehension, we see impacts on concentration, we see reductions in , we see fewer . So if you look across all these studies and across respiratory diseases or viruses like SARS-CoV-2 or influenza, you see the relative risk difference.

Let's say studies showing a twofold relative risk decrease with higher ventilation and likelihood of getting influenza. In terms of impact on student learning, you could take some of these really big studies on learning or reading comprehension. You see differences, 5%-10% differences, in math scores or reading scores just by minor improvements to ventilation. I'm not talking about some multimillion dollar fix to the school either. To your point, just open up the windows a bit more, get these ventilation rates higher.

I think this is one of the challenges, and I just talked about this with a group yesterday, our Lancet COVID-19 Commission Task Force on Safe Work, Safe School, and Safe Travel put out a on new proposed health-based targets for ventilation. And people ask that question, "What's the percent benefit I'm going to get?"

I think, as you know with COVID, it's really hard to say; it depends on the population, the mix of vaccination, age, waning [immunity], prior infection, all these factors.

But I think we can think about it similarly to how we think about masks or other things, right? So with N95, what's that going to do? Reduce your exposure by 95%. Simple stuff, right? It's the same thing if you think about air changes per hour: if you hit our targets, you can reduce exposure by 95%.

Early on in the pandemic, we talked about this simply with masking, ventilation, filtration, even prior to vaccines, you could quickly reduce exposure by 95% or more -- actually closer to 99% -- just through those things: masking and ventilation. Prior to the vaccine or anything else that we have going -- any distancing.

So anyway, it's a long-winded answer. The short answer is we have a report from the Lancet COVID-19 Commission on Schools, and in the table in the back it talks about the multiple benefits of ventilation and lists at least 10 different studies where we report the relative risk and what these studies found when ventilation was approved across these different dimensions of concentration, reading, and infectious disease transmission.

Faust: Two questions on that. One is, how much of this is a cumulative thing? In other words, you take one school that didn't do it and one that did and check in a year later versus literally the same day, "Oh, there's a flu outbreak? Open the window, bring in that extra air filter." How much of it is just immediate proximal risk as opposed to a cumulative risk exposure? Like if you live in a city that's got a lot of pollution, you're not going to do as well as if you live with clean air.

Allen: I think it's both.

Our team at Harvard put out some on acute effects of ventilation and reductions in particles on immediate impacts on cognitive function test scores. So, you follow these people all over the world at their office desk, you put an air quality monitor out, and you give them a cognitive function test. The particle levels, outdoor air pollution, and the CO₂ levels in that moment have an immediate impact on your performance on cognitive function tests. So, it's immediate.

If you think about the more long-term or chronic, cumulative effects, well, risk is a function of exposure, intensity, frequency, and duration, right? So you keep reducing your risk over time of catching any or all of these viruses that are circulating each time you have a higher ventilation rate.

Definitely, if you're having an outbreak in a school, take this measles outbreak that's happening right now, right? Of course, number one strategy: vaccinate. We wrote a paper 2 years ago also showing that ventilation lowers the risk of measles.

The first thing they should be doing right now while they have the vaccine campaign going is get those windows open and get the portable air cleaners with HEPA filters. These are things that can be done today.

Anytime you have this immediate, acute thing, if kids in class have this and you have two or three kids that have COVID or have influenza, take these steps to reduce the risk in the moment too. So the ventilation and filtration benefits are both in the moment, but also have the longer-term benefits as well.

Faust: All right. Let's do an extravaganza on these things [CO₂ monitors]. I got one of these when my kid got COVID. I did what everyone wishes they could do, I called Joe Allen, and you told me what to do. And I will say, you know, it's an N of one, it's anecdotal, but I have a household with an infant, a 4-year-old, and two adults, and the 4-year-old got it and none of us did.

Now we're fortunate, we have resources, we have space, it was summer, so we could open every window, but this is when I got this thing. I learned a lot from this, and people have questions about this. Obviously it's a portable CO₂ monitor. This one was a couple hundred bucks, $200, and it's a proxy for how good the air quality is. It's definitely not a proxy for COVID exposure, it's just CO₂. It has nothing to do with that.

Allen: So we know ventilation and filtration are good for reducing risk from COVID. We now have these relatively cheap tools. I have the same monitor here that I'm holding up. I have three or four behind me connected and I test them all out. We now have the ability to make the invisible visible.

So, how do you know if air quality's good in your space? Well, how would you know? It feels stuffy in here? I don't know. But now you have a monitor. It's a really useful tool and a quick proxy, a quick way for people to understand how well your space is ventilated.

To put some numbers on this, typically my field has thought for a long time that if it's under a thousand parts per million of CO₂, that's typical ventilation. We like to see less than 800 parts per million. But there's another catch. We're talking a lot about ventilation and filtration, right? CO₂ is only telling you about outdoor air ventilation. The filters you might use in a HEPA filter, your portable air cleaner, aren't capturing CO₂.

So if you have low CO₂, you're in good shape. If you have high CO₂, it doesn't necessarily mean it's bad, because you might have a great filter game going.

Faust: Let's talk a little bit about mitigation. Again, I like the idea of giving people something that they can use.

When someone goes home for the holidays, and of course we would recommend rapid testing before you get together with people, especially vulnerable people, and masking when you can, but what difference would it make -- something as simple as opening the windows for 15 minutes an hour? Because I noticed when I was driving my car recently, I had my CO₂ thing, and after opening the window there was an immediate difference. It was unbelievable, the difference.

I guess it's a proxy, but the point is that it didn't take long even with a crack of a window open. So if people don't want to really be disrupted, and you just said, "Open the window for like 15 minutes an hour or 10 minutes an hour. Even if it's cold -- just that little bit." What kind of difference does that make?

Allen: Well, it makes a massive difference, and you see it in the car example. I mean, Rich Corsi, Jack Spengler, and I wrote a . People were worried about getting in cars or Ubers; we model that if you crack the window an inch or two, you see it in the data, the CO₂ drops. It starts to look like outside; you get lots of air movement.

Also, what happens when you're in a car for too long with a lot of people with windows up? You get tired, right? That's the ventilation. You're not going to get enough ventilation. The same thing happens when you're at home.

I do some simple things, right? Everyone in my family's vaccinated, boosted, updated on our boosters. We're doing good on that front. I think our risk has largely dropped, the risk of severe disease has largely dropped, but it doesn't mean we want to get it. So we're not wearing masks when we gather. But yeah, we cracked open the windows just a little bit.

I mean, do an experiment. Someone could take that CO₂ monitor in their office, crack open the window, or let the CO₂ build up and then open the window, and see what happens. You'll . Quickly you'll see a drop under the thousand parts per million level, you'll see a drop under 800 parts per million, and that's a really good indicator.

They don't even have to be thinking about the filtration effects. If your CO₂ starts dropping under 800 and you've got the window cracked a little bit, you're in really good shape. Because our homes actually are really poorly ventilated across the board.

Faust: All right, thought experiment: Let's say that right before Thanksgiving, during Christmas, New Year's, and maybe January, you require every school to open the window in the classroom for 15 minutes an hour, every nursing home to open the window 15 minutes an hour. What do you think the reduction in morbidity/mortality from flu, RSV, and COVID would be just from that?

Allen: I'm not sure I'd go the 15 minutes an hour, fully open. I would even take just cracking it a couple inches and get some baseline changes.

I'll put some numbers on it. Let's say the school is getting one air change per hour in this season, right? By opening up the windows or making sure the ventilation system's working, you get it up to three or four air changes per hour. You have a fourfold reduction in exposure immediately, right off the bat. That's massive.

Look at some of the modeling we did with the , which I think was really helpful. It was a visual, we did tracer gases essentially for people's breaths, and it fills up a classroom. What happens when you open the window and put an air cleaner in is you see that if someone's infectious, they're emitting still, but they can no longer impact somebody on the other side of the room.

In other words, you can't have a 90% attack rate like we were having early in the pandemic. It's diluted too much. Yes, people can get sick, anything can happen, but you're reducing the risk dramatically from these simple steps. I really think it's critical.

I like where you went. I think it's important to focus on those at most risk of disruption. I think for kids in schools and those most at risk from severe COVID, and that's people who are older, I think we need a lot more attention on senior living, congregate care, where I don't know if all these ventilation filtration recommendations have really penetrated.

You want to make an impact? You see the curves going up right now from hospitalizations? It's nearly entirely all in those over 65. In addition to vaccines and boosters targeted towards this group, the ventilation and filtration improvements would lead to the biggest benefit right now related to COVID. Doing this more broadly, including schools, would lead to bigger benefits in terms of COVID, RSV, and influenza.

Faust: All right, last question. You have two audiences, really. You have the individual and you have the big systems. Sometimes I think about these questions in terms of, "Well, my carbon footprint is a drop in the ocean because some one company does a hundred thousand times more than I ever will. So whether I recycle this Coke can or not, this really doesn't matter."

Do you think the solution is really wrapped up in sort of the big picture, almost like the friction-free stuff, the decision has been made for you. You go to a school or a business that has good air as opposed to what you do at home is just sort of a drop in the bucket. Who do you think bends this curve more, the individual or the system?

Allen: Well, we need a system-wide approach, and I'll tell you why. The message is starting to get out there, but you look at who's making the changes and it's always well-resourced individuals, it's well-resourced schools, it's the big companies. They're all doing this. I'm not worried about them, right?

But if we don't codify this -- and by this I mean that the current ventilation targets are too low -- you will find widespread agreement on that. They're not health-based. If we don't set new standards and new codes based on health-based benchmarks, it's not going to hit everyone everywhere and the disparities will widen even further. So yes, I'm heartened that we have a big focus here, but this is a huge equity issue.

Until it gets built into the codes for buildings -- you don't want to think about it, I don't want to think about it, I just want to be in a healthy home, I want go to the store and I want it to be a healthy place, my office should be a healthy place, right? It has to be built into the codes.

Right now, code is based on these bare minimum ventilation standards. The standard is called the "standard for acceptable indoor air quality." It's not acceptable. Decades of science are showing it's not acceptable. We got this virus spread entirely indoors that has slammed up against a building architecture and design that's been designed without thinking about health. It's no wonder we've had the disaster we've had. And if we come out of this where healthy buildings are confined to only those people with the resources, it'll be a gross, gross failing -- gross in all meanings of the word.

So I see some movement happening, but this is where my field and everyone else needs to keep pushing. We have to change the standards so that just becomes the norm. Just becomes the norm.

Faust: Joe Allen, thanks so much for joining us. Your book Healthy Buildings is also extremely interesting reading. Thanks for joining us.

Allen: Yeah, thanks. I enjoyed the conversation.

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