Breathless: Climate Change, Infectious Disease, and Indoor Air Quality

July 12, 2023

Challenges in areas ranging from education to the environment, gender to governance, health to housing don’t exist in a vacuum. Each month, Abt experts from two disciplines explore ideas for tackling these challenges in our monthly podcast, The Intersect. Sign up for monthly e-mail notifications here. Catch up with previous episodes here.

To improve energy efficiency and reduce greenhouse gas emissions, government agencies called for air-tight buildings. To reduce the transmission of COVID and the impact of pollutants emitted in homes by products ranging from stoves to personal care products, scientists and engineers looked for ways to improve air circulation. As harmful particulate matter from wildfires crosses international borders, we’re reminded yet again that safeguarding air quality for public health is a balancing act that we can’t afford to get wrong. Drs. Tiffany Harris and Jonathan Dorn discuss the challenges—and possible solutions.

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Read the Transcript

Eric Tischler: Hi, and welcome to the intersect. I'm Eric Tischler. Abt Global tackles complex challenges around the world, ranging from improving health and education to assessing the impact of environmental changes. For any given problem, we bring multiple perspectives to the table. We thought it would be enlightening and maybe even fun to pair up colleagues from different disciplines so they can share their ideas and perhaps spark new thinking about how we solve these challenges. Today I'm joined by two of those colleagues, doctors Tiffany Harris and Jonathan Dorn. Tiffany is an epidemiologist with over 20 years of experience in research, surveillance, monitoring, evaluation, and data analysis for infectious and non-infectious diseases. Jonathan is a senior environmental scientist and policy analyst with broad experience in global climate change, renewable energy, and air pollutant emission inventory development. Welcome!

Jonathan Dorn: Thanks, Eric. Pleasure to be here.

Tiffany Harris: Thanks, Eric. Great to be here.

Eric: Before covid, indoor air quality probably seemed like a manageable respiratory and quality of life issued to most. Over time, you recognized how inefficiencies in our structures contribute to climate change, and the need for energy efficiency became more urgent. Then the onset of COVID demanded that we look at how our indoor environment affects the transmissibility of infectious diseases. All these concerns remain urgent, and their context remains the same. They impact our indoor air quality. So how do we address the need for different and seemingly competing solutions to related problems? Uh, let's go in chronological order. Jonathan, start with you. From an environmental perspective, what have we historically been solving for when we talk about indoor air quality?

Jonathan: Yeah, so I think when discussing air quality, it's important to understand the linkage between indoor air quality, outdoor air quality, and people's behaviors. One statistic that I find interesting is that most people in the United States spend about 90 percent of their time indoors. This means that indoor air quality can really have a big impact on people's health, and that we should search for ways to improve this indoor air quality. A lot of the indoor air pollutant sources that we're exposed to are the releases of gases or particles which are associated with cooking on gas stoves or volatile organic compounds that are released from new furniture. Or when you wake up in the morning, you go into your bathroom, you start using your personal care products and cleaners. All of these things are emitting pollutants, and exposure to these pollutants are known to lead to really poor health outcomes, such as asthma and heart disease.

And it's really known that inadequate ventilation can increase indoor pollutant levels while not bringing in enough fresh outdoor air to dilute emissions from the indoor sources. And really, you want to be carrying a lot of these indoor air pollutants out of your home. Yet the ventilation of homes and buildings are being reduced because of what you mentioned, as we are implementing energy efficiency measures to address climate change. And so, a lot of these measures essentially are sealing the building envelope that is preventing the exchange of indoor and outdoor air. So as a consequence of this, we're really seeing a rise in the concentration of indoor air pollutant and associated illnesses. And all of this is really being compounded by the increased use of cleaning and sanitizing agents that are helping to prevent the spread of COVID-19.

Eric: Thank you. That's a great segue to you, Tiffany. So COVID comes along and how are concerns about COVID now affecting indoor air quality and, and our approaches to it?

Tiffany: Yeah, so if everyone remembers way back, um, at the beginning of the pandemic, it was really thought that that SARS COV 2 was mostly spread by droplets, which are these larger particles. And because they're larger and heavier, they don't really stay suspended in the air for very long, and they'll follow the air onto a surface or onto somebody near you. So, the guidance was really focused on cleaning surfaces. We were all cleaning everything that we brought into the house, right? And also staying six feet away from others. However, it became pretty clear that what's called airborne or sometimes aerosol transmission was actually probably the biggest transmission route. So, this is when someone coughs or sneezes or even talks, they generate these smaller particles that because they're small, they can stay suspended in the air for a long period of time and actually can travel pretty far.

And so that's when all the masking recommendations came out. And I think if there is a silver lining to the pandemic it’s that we have a much better appreciation of the role at indoor air quality in the transmission. Not only SARS COV 2, but many of the other respiratory viruses, such as influenza and RSV. Healthcare settings for years have had things in place to prevent, you know, transmission of respiratory viruses. But now we've been thinking about indoor air quality and transmission in non-healthcare settings, like school office buildings or even, you know, public transportation like buses or trains. Improving indoor air quality can be a really important tool in our prevention toolbox because it's a population-level intervention that doesn't necessarily require really individual behavior change. And what's also good is it addresses asymptomatic and pre-symptomatic transmission. So, you know, we all know we should be staying home when we're not feeling well. There are the masking recommendations as well, but you may not have symptoms and not realize you're sick yet. So indoor air quality can be a tool to help address that as well.

Eric: Great. Okay, so the good news is we have greater awareness, but then we're still looking at challenges that seem to be conflicting, right? We need airtight solutions, we need ventilated solutions. So how do we thread the needle when looking at these sort of competing needs?

Jonathan: Yeah, I think that's an interesting question. And I wanna start answering that by talking about the environmental justice implications of what we're seeing here in terms of indoor air quality. So, there's been a growing body of research in the last five years that really suggest that low-income minority communities—including tribal communities—are disproportionately impacted by indoor asthma triggers such as allergen, secondhand smoke, mold, radon, and all these other indoor pollutants. As we just mentioned, there's a direct correlation between indoor and outdoor air quality. And another interesting statistic is that according to the American Lung Association's 2020 state of the air report, people of color are about one and a half times more likely to live in an area with poor outdoor air quality than white people.

And so now, you know, as we face the pandemic and are looking at solutions to COVID 19, there's emerging research that's found that even exposure to small amounts of air pollution, including indoor air pollution, over a long term can make someone 8 percent more likely to die from COVID 19. So, there's now a direct link between exposure to poor air quality and contracting and dying from COVID 19. And we see this reflected in Black and Hispanic communities as those communities were hit hardest by the virus. And so, I think as we try and look at solutions on tightening the building envelopes, we need to be very careful that we are also designing for adequate ventilation and filters that can remove the indoor air pollutants.

Tiffany: Just to add on that, there are several approaches we have now for improving indoor air quality when we're thinking about virus transmission. You know, some you might think about the easiest way is just opening a door or window. Well, you might live in an area where that's not very feasible either because of crime concerns, safety, other safety concerns or because, as you know, was mentioned, the outdoor air is not that great either, right? So, you don't wanna be triggering people's asthma or other issues by bringing in the outdoor air. And then a lot of the other solutions can be very expensive, right? Overhauling a building’s HVAC system, putting in these UV lights that can kill the virus. And so, you know, a lot of these solutions are complicated and pricey, and other ones have their limitations.

And so, we really gotta bring, I think, an equity lens in applying these solutions and make sure it's not just wealthier neighborhoods, wealthier institutions that have access to the ones that work better. Also, we don't actually know which ones work the best. A lot of the studies that have been done have really just focused on environmental sampling. So just seeing like, oh, you put a filter in, you test the filter for a bunch of viruses, what do you find? And very few studies have actually tied the presence of different interventions into improving air quality to infectious disease outcomes in humans. So, we need a lot more studies and we need to make sure those studies are done in an equitable way. And, you know, all sorts of populations are engaged in those.

Jonathan: As Tiffany was just saying, we need to really focus on the solutions not only for affluent households, but also looking at lower income households. So, the link between poor access to safe and healthy homes and the disparities in health status among different subpopulations is really kind of intriguing. And, so, really, to better understand the impacts, Abt is currently supporting the U.S. Department of Housing and Urban Development to evaluate whether their voucher mobility program is leading to improved health. So, this voucher mobility program offers financial resources for families living in areas of low economic opportunity the chance to move into areas of higher economic opportunity. So, in theory, this should really lead to improved indoor and outdoor air quality and reduce pollutant exposure and improved health outcomes. So, this is a two-year study, tracking families that are moving from these low economic opportunity areas to higher economic opportunities areas, really monitoring the indoor air quality changes between their old house and their new house. And looking at how their health is actually improving when they get into areas where the air quality is better.

Eric: Do you want to be a little more explicit about why there might be a change in that quality when they make that move?

Jonathan: So, we anticipate that the changes that will result from moving from the low economic opportunity areas to higher economic opportunities areas comes in several cases. So, one is that in the low economic opportunity areas, it's more likely that you're gonna be living in industrialized areas. So, you're gonna be in close proximity to highways, to industrial facilities, to power generation facilities that are releasing a lot of pollutants and lowering the air quality in the outdoors. And this is gonna impact your direct indoor air quality through the exchange of indoor and outdoor air.

In addition, in these lower economic opportunity areas, you're more likely to be exposed to allergens such as cockroach allergens and, and mice allergens that are prevalent in low economic areas. And we would expect to see an improvement as the families are moving into these higher economic zones that are removed from the proximity of these industrial facilities and have better approaches to pest management.

Eric: So, you know, we're talking a lot about the built environment and zoning and redlining, but let's talk a little bit about climate change. You know, as we're recording this, we just saw some really terrifying air pollution here in the United States as a result of wildfires in Canada, obviously the result of climate change. You know, again, we're talking about that indoor-outdoor exchange. How is that changing the calculus, if at all, as we anticipate seeing more events like that?

Jonathan: Yeah, thanks Eric. I think that there is this direct link between climate change and indoor air quality. And, as you mentioned, the East Coast is currently experiencing poor air quality due to the particulate matter and the smoke from the Canadian wildfires that's drifting across the eastern United States. So, this smoke and other particulate pollution that's generated outdoors can infiltrate into indoor environments and contribute to increased levels of indoor particulate matter.

In other areas where we're seeing climate change, you sometimes have increased precipitation and this increased precipitation, as it becomes more common, leads to a much wetter environment. And this really promotes the growth of mold, dust mites, bacteria, and other biological contaminants that really can reduce air quality because they really thrive in these like damp and humid conditions.

Another consequence that we're seeing from climate change in these extreme weather events is that power outages are becoming more and more frequent and, without power, it's really difficult to maintain comfortable indoor temperatures and ventilation needed to maintain healthy, indoor air quality. So, in a situation like we're experiencing now with the Canadian wildfires, really poor outdoor air quality, if you have a situation where your power is also out and it's becoming really warm in your house and you open your windows to try and increase the ventilation, you're actually exposing yourself to much higher levels of, of particulate matter that can lead to health problems. And another big issue with these power outages is that people often turn to using portable generators and portable generators release carbon monoxide. It's an odorless gas that's very poisonous to breathe, and there are literally hundreds of deaths and thousands of illnesses each year in the United States from the improper use of these portable generators.

Tiffany: Yeah, many people who've been dealing with the, the current smoke conditions have found the smoke is very irritating, right? Like, even for an otherwise healthy person, it can result in their eyes burning, coughing, skin irritation, but we really worry about people who have preexisting conditions. Wildfire smoke trigger asthma attacks but also can trigger heart attacks and strokes, especially in those who have preexisting conditions. So, it's definitely something to worry about, especially as this becomes more common. Also, you know, one thing to remember is, when it's the wildfire smoke, it's not just trees burning, but it's cars and buildings. So, there's a lot of, as Jonathan said, particulates in that and a lot of contaminants. And we don't even entirely understand sort of what the long-term consequences are to repeated exposure to those contaminants, and repeated exposures may well become more common as, as we see wildfires grow and become more common.

Eric: You know, both of you and our colleagues have your eyes wide open about what the multiple fronts are that we're facing this on. So that's the good news. You know, Jonathan, you already mentioned work that we're pursuing with HUD. Tiffany, you mentioned some of the work we can and, and should be doing to help us understand how we might better respond or identify what better responses would be. Anything else you all want to add about what we can do moving forward.

Jonathan: Okay, yeah. And, maybe to end on kinda like a positive note, I'm just trying to think how like we reframe this is that really you have to, you have to understand the problem before you can develop a solution--

Tiffany: Yeah, yes.

Jonathan: … and that's really happened in the last couple years, is we really understand the problem now, and now we're primed to go full steam ahead in the research and solutioning,

Tiffany: There is a greater appreciation for the role of indoor air quality on respiratory virus transmission. The CDC has been putting a lot more about out about this. And, about a month ago on May 12th, they actually released updated indoor air quality guidelines, aimed to reduce the spread of SARS COV 2. But this also applies to other airborne viruses and hazards. And, for the first time, they're recommending a minimum number of air changes per hour, which is five. And also recommending upgrading central HVAC systems to have a certain level of filter efficiency. So, these will help building owners and others make sure their buildings address these and reduce viral transmission.

Also, the EPA has released this clean air and buildings challenges, which is a call to action and a set of guiding principles and best practices to assist building owners and operators to reduce risk. So, I think there is definitely a growing appreciation and improved guidance. However, there's still a lot we don't know and we need to study, so we need to describe the situations and evaluate interventions and see how they impact human health.

Eric: So that's great, Tiffany. Like you said, there's more work to do but, like you said, Jonathan, you’re doing work right now with HUD and, like you said, Tiffany, um, we're getting guidance to help us. So, it may be a multifaceted challenge, but at least we're all moving forward towards resolving it. Thank you for doing that work.

Tiffany: Thanks Eric, for this opportunity to discuss.

Jonathan: Yes, it's been a great discussion. Thanks.