As of Jan. 12, 2021, more than 23.25 million cases of COVID-19, or the coronavirus, have been reported in the U.S. More than 387,000 people have died from complications related to the disease.

Dr. Stephanie Taylor, a graduate of Harvard Medical School, is the CEO of Taylor Healthcare Commissioning Inc. After working as a physician for many decades, Dr. Taylor obtained a master’s in architecture as well as an infection control certification. Her lifelong commitment to patient care includes focusing on improving the health care physical environment and clinical work processes to help patients heal quickly and save hospitals valuable dollars.

Recently, Dr. Taylor joined Herb Woerpel, editor-in-chief of Engineered Systems, to continue a conversation on the virus that began back on March 17, 2020. Here is a transcript of that conversation.



Engineered Systems: We last spoke on this topic in June, which is hard to believe, but that was six plus months ago. So what have you been up to since then? I imagine you've been quite busy.

Dr. Stephanie Taylor: Well, one thing I have not been doing is sleeping. But, yes, it's been incredibly busy trying to help mitigate indoor transmission of this virus, in particular. It's also really rewarding to be in a line of work, where I actually feel like I can contribute something positive to the outcome of this pandemic. So, it's been busy and also really gratifying.


Engineered Systems: Perhaps the biggest news on the COVID-19 pandemic front is the availability of two vaccines. Can you share your initial thoughts on these vaccines and the potential impact they may have on the engineering industry?

Taylor: So, my initial thought about the vaccine being developed so quickly is, you know, I'm really grateful that we can now sort of bolster people's immune system, which is key to this concept of herd immunity. So, that's the very, very good news. On the other hand, I hope that once people are vaccinated that we don't forget about the ability of the indoor environment to protect human health, not just from viral respiratory disease. But, in general, the indoor environment has incredible capability of promoting human health. I hope we don't lose sight of that.


Engineered Systems: So, just to reiterate — based on your expertise, you consider the Pfizer and Moderna vaccines safe? I know they were certainly rushed to the finish line…

Taylor: You know, as far as I know, they are safe. My son, who is an emergency room physician, is actually getting his vaccination today. So I've read a lot about them. I believe they are safe. This approach of engineering around cellular messenger RNA is certainly new and potentially very, very powerful, not just with this infectious disease but for other diseases. Clearly, it was developed in 10 months, so we don't know the long-term side effects. Though, I'm just hoping that any early indication of problems has already been detected. So, I feel quite confident, and a little bit wary, but mostly confident that they’re good and that this is a good vaccine strategy.


Engineered Systems: Now, I don't want to get everyone's hopes up, but assuming a large percentage of Americans receive this vaccination, when do you suppose we'll be back to “normal?” Of course, this is assuming everything progresses as planned. 

Taylor: So, that's a hard question. You know, they say there will be no normal, or we will have a new normal. I believe that by July things may be back to “normal.” The outdoor climate influences the indoor climate and that will certainly help the decrease disease transmission. In addition to that, I believe that by July most people will have received both doses of vaccinations. So, I'm really hopeful that early next summer we will be back in full swing.


Engineered Systems: We've come a long way over the last nine months, and it's certainly been a long nine months. What's the science telling us today about the spread of the SARS-CoV-2 virus? And how do today's recommendations differ from those that we were following just a few months ago?

Taylor: Oh, my gosh, that's such an interesting question. And it's been a fascinating evolution of public understanding of transmission of the SARS-CoV-2. Initially, the CDC and public-facing organizations were focusing on surface transmission and large droplet transmission that were transmitted within 3-6 feet or 1-2 meters of the origin. We've known for forever, really, that viral diseases are also transmitted through small aerosols and small desiccated or dried-up particles that can travel for much greater distances. There was reluctance around acknowledging that, but we finally saw the CDC and the World Health Organization acknowledged in September, I believe, First, they acknowledge long distance airborne transmission, and then they retracted it, and then they reissued it. But, if you listen to Dr. Fauci, the CDC, and the World Health Organization, they're now acknowledging that airborne transmission is probably the most dominant transmission root of this virus. So, we still need to pay attention to surface hygiene and hand hygiene. But the concept of airborne transmission really highlights the ability of the indoor environment to mitigate the spread of disease.


Engineered Systems: Based on the research and the knowledge you've accumulated, as a facility manager, what IAQ technologies or approaches should I consider to help decrease the spread of COVID-19?

Taylor: That's another great question. You know, what should facility managers be doing to protect their buildings and to help people feel confident about that? Really, there are two different questions in there. Making people feel confident about reoccupying a building could be implementing the visibility of a technology, which may not necessarily the best one. And so that's a question that I think has to be really carefully considered. In my research, starting in hospitals, one indoor variable that has revealed itself as being incredibly protective is mid-range relative humidity of 40%-60%. So, if I were to choose one intervention, I would monitor and manage the indoor relative humidity, as I think it's absolutely key. Thankfully, it's synergistic with some of the other technologies that we talk about, including outdoor air, ventilation, and filtration. So, it's not mutually exclusive. That said, overall, I think umidification is probably the most important intervention I would consider.


Engineered Systems: Now, I know the answer to this question because I’ve been following your posts on LinkedIn, but should we simply sterilize every surface in our homes until the paint starts to melt?

Taylor: So, should we be sterilizing the indoor environment? Well. No. 1, that's impossible. But, thankfully, it's also not the right approach. So, if you talk about the average building occupied with immune-competent individuals — meaning people who are not severely immunocompromised — you actually do not want to eradicate all microbes, bacteria, and viruses, because 95% of the viruses and bacteria in the environment and on and in our bodies actually promote health, and we can't live without them. So, if you try to eradicate all organisms, the risk is that you simply open the way for the pathogenic ones, the disease-causing microbes, to take over the environment. And that's very destructive to our health. So, no, you don't want to eradicate everything.


Engineered Systems: Thanks to the efforts of you and your colleagues, it's become nearly common knowledge that indoor humidity levels, specifically, those in the range of 40 to 60% play a key role in diminishing COVID-19 as well as other airborne pathogens. As you mentioned earlier, this is your chief recommendation when it comes to eradicating the spread of COVID-19. Can you just tell us a little bit about the science behind this beneficial humidity range?

Taylor: This is very exciting. It's so powerful. Indoor humidification is such a powerful way to control disease transmission, and it's also so simple. It's almost too simple for people to believe it. But there are really four ways that indoor humidity levels, relative humidity of 40%-60% are beneficial. So, first of all, when you have that degree of water vapor in your air, the particles that are airborne become larger, glom together, or they simply don't desiccate as much, and so they settle out of the breathing zone. So, No. 1, you have fewer airborne particles that are potentially infectious. Secondly, for reasons we don't fully understand, many viruses and bacteria are less active or virulent when they're in expired droplets in that mid-range humidity zone. It's not true of all viruses and bacteria. But I believe it's Mother Nature's gift to us that many bad pathogens and bad microbes are less lethal in that mid-range humidity zone. We don't really know the science behind that. Thirdly, we now know that the human respiratory immune system is more functional when the ambient relative humidity is in that range. And, conversely, when it's dry, say 20% relative humidity, many steps of your respiratory immunity are impaired. And then, No. 4, and you alluded to this before, for the indoor microbial populations, the good ones are actually more diverse when you have that mid-range humidity. And that's a little bit harder for a lot of people to wrap their heads around, especially in a time when we're fighting a virus. It's really hard for people to understand there's some organisms that are good for us, but a more diverse microbial indoor ecosystem is actually beneficial.


Engineered Systems: We're well into January now. And, here in Michigan, and in many spots across the country, we're not opening our doors or windows at all. What role does the lack of natural outdoor air play in the spread of this virus?

Taylor: Well, natural ventilation is effective in diluting if you have clean outdoor air. In that case, ventilation is clearly beneficial in diluting any indoor contaminants. If you can't do that, because it's freezing cold out and you don't want to have your energy bill go sky high, you need to implement other strategies. So, humidify your indoor environment and use filtration. Clearly, there will be some degree of recirculation, so try to have some outdoor air ventilation, if possible. But, in the meantime, it’s important to humidify and use filtration within commercial buildings. Technologies like ultraviolet germicidal radiation are effective in the ductwork at cleaning coils and making sure you don't have pressure drops across filters. So, you're not doomed if you don't open your windows and doors but you do need to maximize other interventions.


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Engineered Systems: One exciting endeavor for you is the Building4Health company. You guys recently launched a website. Can you tell us a little bit more about this, the brains behind it, and what you hope to accomplish? 

Taylor: I love talking about Building4Health. So, my whole awareness of the value of indoor relative humidity in this mid-range zone was an offshoot of a project in a hospital where we actually looked at human health patient healing as a response to the indoor environment. So, we take data from patients and from a building and analyze them simultaneously. And we found how powerfully important humidity is. So, if you take that concept of viewing the building from the perspective of human health, you can really target your interventions and operational steps for people — not just for decreased energy use but in the name of having the beauty of many windows. So, it's kind of a new perspective on buildings. We're using sensors or monitoring stations, which are easily installed. We're collecting data from buildings and we're analyzing the data from the perspective of human health. So, it's different from other certification processes because we're integrating infectious disease and industrial toxin level data and understanding the impact of these things on the human immune system and looking at the effect on the indoor microbial communities. So, we’re bringing science together and analyzing our data from the perspective of health and then giving feedback to the building owner or manager. You know, there's no point in saying do something that either is prohibitive from the budget or outdoor climate. So, it's exciting because it's both. It's specific to human health and it's also actionable for the building owner.


Engineered Systems: You are a member of the ASHARE Epidemic Task Force. Regarding that group, is there anything new or breaking that we need to be aware of?

Taylor: Not really. Our recommendations have shifted as the outdoor climate has become colder. In the summertime, we're recommending higher levels of outdoor air ventilation. Now, we've modified those recommendations to be realistic, given the cold outdoor temperatures in many parts of the world. So, we're discussing more about ways to treat the air when you do have to recirculate it. But our basic recommendations are the same. MERV-13 filtration, utilize a number of air changes, and use as much outdoor ventilation as possible to achieve 40%-60% indoor relative humidity. And then, in terms of air-cleaning technologies, we're supporting the ones where we can find a good number of peer-reviewed scientific articles. So, there are some strategies that we haven't been able to analyze enough data on, so we're really sticking with the ones that we’re most comfortable with.


Engineered Systems: We certainly enjoy all of your columns and the work you do for us here at Engineered Systems, but one recently caught my eye. This one was titled “Batman Survives COVID-19.” In that column, you asked the question: Why can bats — small mammals with many similarities to humans — live with coronavirus infections without appearing sick? I think that's a great question. Could you summarize the answer for us?

Taylor: Looking at how bats respond to viruses as opposed to humans is a really fascinating window on this whole topic of managing our environment to support health. Why do bats do fairly well with a virus when humans often don't? The first line of inquiry was to compare the genetic makeup of bats in humans, and that didn't solve the question or answer the question. As far as we know, it comes down to one important thing in that when they are exposed to a virus, their bodies secrete a very healthy amount of interferon, which is a protein that's synthesized by your respiratory system. When a bat gets a viral infection, interferon levels go up quickly, which recruit the rest of the immune system. This helps the bat manage the infection. But, with humans, and, again, especially when relative humidity is low, our respiratory epithelium, the cells that line our respiratory tract, are very delayed in their interferon production as well as some other protective proteins. And this is the work of Dr. Iwasaki at the Yale immunobiology lab. When you have a delayed interferon response, the virus can settle more deeply into your lungs and mount a more serious infection. Then, your immune system wakes up and says, oh my gosh, you know, there's a virus in there. And then some people get this overreaction called a cytokine storm, where their immune system goes into overdrive and actually causes more tissue damage on top of the infection. So, bats don't have that problem. They live in a very well-modulated relative humidity environment. And then, surprisingly or not surprisingly, their microbial communities are very robust. So they don't select just the bad pathogens. Bats are not busy cleaning surfaces and washing their wings or their little paws. So, they're not saying we want to live with that guano in our hospitals. But bats have a very robust immune system because they're exposed to so many healthy microbes. I don't recommend that but I do recommend understanding how the indoor environment affects our immune system because clearly that's essential in being healthy. So, again, in summary, dry air is bad.


Engineered Systems: Through the evolution of this virus and where we're at with the vaccines, what's the most important thing a facility manager should be thinking about right now when it comes to ensuring her buildings are in peak condition?

Taylor: So I think the first thing we should do, like any important issue, is make visible the components that affect our health. That's why my work is really heavily focused now on monitoring the indoor environment from the perspective of human health because we don't want to be putting in interventions in buildings that's already doing well. At the same time, we don't want to put in the wrong intervention that is going to cause problems down the road, such as promoting the evolution of more virulent or infectious pathogens. If I had a given budget for building No. 1, I would put in an affordable monitoring system first. Secondly, the biggest problem in the temperate climate in the wintertime is dry indoor air. So, I would talk to somebody who knows about humidifiers. Then I would take care of any insulation problems that exist that may lead to liquid condensation in your building. While you might not be able to get to 40% minimum humidity in all buildings in a northern cold climate, you can at least approach that healthy level. 


Engineered Systems: One final question here for you, and I always seem to save the best for last. Recent headlines have reported on a new coronavirus mutation over in Europe. What can you tell us about this and how significant is the threat of this new stream? Please tell me we're not going to be locked in our homes for another year!

Taylor: So I would be much more alarmed if this coronavirus had not evolved into a new mutation. Every other coronavirus known to humankind — and actually not just coronaviruses but single-stranded RNA viruses in general, which is what a Coronavirus is — mutate rapidly and create new strains. For the most part, these new strains decrease in variants or in degree of badness. So, with this mutation that we're seeing that started in the U.K., it's pretty clear it’s transmitted more easily than the first one that we've been battling with. There's absolutely no indication that it's more virulent and there's no indication that the vaccine won't bolster our immunity against it. So, again, it's typical behavior for a coronavirus to change. And, again, in general, when viruses are in the human population, over time, they decrease in virulence. So, I'm more worried about what the press does with news like this than the mutated virus itself. People are now understanding a little bit of science but not a lot. And, so, I worry about people's state of mind. I think it's scary for many people, but I personally am not concerned about it.


Engineered Systems: Well, that's fantastic news. Dr. Taylor, we've covered quite a bit in this time, but is there anything else you'd like to add while we have you on the stream?

Taylor: This is unprompted, but I love Engineered Systems. I've been writing columns for you for quite a few years and I find that readers are supportive of the different angle I offer, that of a physician with an education in engineering and architecture. Herb, your support and ability to think outside of the box perspective has been absolutely fantastic. I really appreciate it ES!


Engineered Systems: Thank you so much. We're grateful to have you on staff as well. If readers are interested in connecting with you or have any additional questions, where should they turn?

Taylor: So you can email me at or reach out to you Herb at the magazine and you can forward the message. I’ll also encourage people to visit me on my LinkedIn profile. 


Engineered Systems: Thank you so much, Dr. Taylor. We wish you the nothing but success in the year 2021 and beyond.

Taylor: Thank you, Keep your hopes up everyone. We’re going to come out of this all just fine!