How Much Do Fine Particulates Matter for Public Health?, with Inês Azevedo

Top Quotes

• Air pollution and race: “We estimated the health effects of air pollution from electricity generation for different regions, for each US state, and by income and race … We found that the exposure is higher for low-income households than for high-income households, but more than that, the disparities are larger by race and ethnicity than income. For example, we find that Black Americans suffer higher premature mortality than other races and ethnicities. We find that the effect is persistent even across income brackets.” (6:20)
• Energy efficiency matters, to an extent: “Energy efficiency has a very important role to play. We do know that we can make use of more efficient end-use technologies in the residential and commercial sectors, all the way from more efficient lighting and transition to LEDs … But things get a bit muddled in terms of how people make decisions and which of those decisions are realistically feasible in the current settings. I would say that the role is important, but the expectation that we would achieve something like full decarbonization via energy efficiency would be highly misleading.” (15:56)
• Tackling climate change and air pollution damages together: “The key point that I would like to highlight is that you can have even larger benefits by tackling climate change and air pollution damages together rather than in isolation. The cost of doing so increases by just a little bit, but less so than the benefits. So, the net benefits for considering those policies jointly are much larger.” (22:43)

Top of the Stack

• “Fine Particulate Air Pollution from Electricity Generation in the US: Health Impacts by Race, Income, and Geography” by Maninder P. S. Thind, Christopher W. Tessum, Inês L. Azevedo, and Julian D. Marshall
• “Optimizing Emissions Reductions from the U.S. Power Sector for Climate and Health Benefits” by Brian J. Sergi, Peter J. Adams, Nicholas Z. Muller, Allen L. Robinson, Steven J. Davis, Julian D. Marshall, and Inês L. Azevedo
• "Energy Efficiency: What Has Research Delivered in the Last 40 Years?” by Harry D. Saunders, Joyashree Roy, Inês M. L. Azevedo, Debalina Chakravarty, Shyamasree Dasgupta, Stephane de la Rue du Can, Angela Druckman, Roger Fouquet, Michael Grubb, Boqiang Lin, Robert Lowe, Reinhard Madlener, Daire M. McCoy, Luis Mundaca, Tadj Oreszczyn, Steven Sorrell, David Stern, Kanako Tanaka, and Taoyuan Wei
• Collaborative late-night show episodes about climate change
• Many recent blog posts from Resources for the Future about fuel economy standards, machine learning, smart thermostats, and the Clean Electricity Performance Program on the Resources website

The Full Transcript

Daniel Raimi: Hello, and welcome to Resources Radio, a weekly podcast from Resources for the Future. I'm your host, Daniel Raimi. This week, we talked with Dr. Inês Azevedo, associate professor of energy resources engineering, senior fellow at the Woods Institute for the Environment, and a fellow at the Precourt Institute for Energy, all at Stanford University. Inês publishes on a very wide range of topics, but today we are going to focus on her work examining the effects of particulate matter (PM) emissions from the power sector and how those emissions affect public health. She'll describe where the emissions come from, how they affect different parts of the country, how effects vary across racial and demographic characteristics, and much more. Stay with us.

All right. Inês Azevedo from Stanford University, thank you so much for joining us today on Resources Radio.

Inês Azevedo: Thank you so much for having me.

Daniel Raimi: Inês, we're going to talk about a variety of aspects of your work, and we're going to focus on the electricity sector in human health. But before we talk about that, we always ask our guests how they got interested in environmental issues, either at a young age or later in life. So what drew you into this field?

Inês Azevedo: I would say that my parents played a role. Both my mom and dad were agronomical engineers and public servants their whole life. My mom also pursued a PhD and taught for a while. Some of their professional work was on allocating funds from the youth commission toward environmental and agricultural projects, and so from early on, I had opportunity to have conversations with them and gain awareness of the importance of environmental issues and climate change.

I was always attracted to questions that weren't related to a single discipline—this interaction between what technologies could do and the role of policies. I wasn't quite sure even what to study, but environmental engineering back in Portugal, where I'm originally from, was the perfect combination of that. So, there was the early awareness from home.

Even after undergrad, I wasn't quite sure what to do. But I had the really unique opportunity to meet someone who drove a lot of my intellectual interests, and that was Professor Granger Morgan. He was visiting Portugal to assess several graduate programs. I had the chance to just sit down and talk with him for a while. We immediately got into fights regarding the role of carbon capture storage technologies and renewables in the future of energy systems. Of course, I had no clue what I was talking about at the time, but it was a very interesting conversation—so much so that I decided there on the spot that I wanted to do a PhD in Engineering and Public Policy in the department where he was at. And he was my PhD advisor.

Daniel Raimi: Wow, that's great. Granger is amazing. We really should try to get him on the show sometime. I haven't been lucky enough to do that yet. That's hilarious. So you start fighting with your PhD advisor.

Inês Azevedo: That continued, and that was the best working relationship because through those fights, we learned a lot—or I learned a lot.

Daniel Raimi: Fantastic. Well, let's get into our conversation today. As some listeners will know, your work touches on so many different areas.

It's hard to know where to focus, but we're going to start with a couple of papers that you've coauthored in recent years on the health effects of particulate matter emissions from electricity generation that's powered by fossil fuels: coal, and natural gas, mostly, but also oil, to a lesser extent, in the United States. Can you give us a high-level overview of how these health effects tend to vary across regions, across incomes, and across races in the United States?

Inês Azevedo: Sure. First I'd like to mention that the paper that you're referring to was done in collaboration with three amazing researchers that I had the opportunity to work with: Maninder Thind, Christopher Tessum, and Julian Marshall.

As you pointed out, power plants in our electricity system emit air pollutants that harm our health in two ways: direct emissions of PM2.5, as well as the emission of other pollutants that then react, and the atmosphere creating secondary PM. Those are SO₂, NOx, and VOCs.

First and foremost, I think the good news is that our grid has become cleaner over time. That’s thanks to environmental regulations that require the adoption of air pollution control technologies, the transition to natural gas into renewable generation, and the fact that we're moving away from coal generation in many regions. But still, today, electricity generation is a large contributor to PM emissions and to the underlying health effects.

Previous research had already looked at the range of premature mortality from the power sector in the United States, and the numbers range from 10,000 to more than 52,000 premature deaths per year. What research had not looked at is how premature mortality depends on or is associated with different demographics. And so that's what we did.

We estimated the health effects from air pollution from electricity generation for different regions, for each US state, and by income and race. Specifically to your question, we found that the exposure is higher for low-income than for high-income households, but more than that, the disparities are larger by race and ethnicity than income. For example, we find that Black Americans suffer higher premature mortality than other races and ethnicities. We find that the effect is persistent even across income brackets. If you look at the higher income brackets, the premature mortality is lower than for others, but we do still see the effect where Blacks and African-Americans have higher rates of premature mortality.

Now, that's one dimension of demographic effects, but we looked at other distributional effects. Geographically, we observed large differences regarding where electricity is produced and where people experience the resulting consequences of air pollution. For example, for 36 states, the vast majority of the consequences come from emissions outside state borders.

Daniel Raimi: That issue of geography is so interesting. I just want to clarify a couple of acronyms that you used in your answer before we go on: PM2.5, that is particulate matter that is 2.5 microns or fewer in diameter; SO₂ is sulfur dioxide; NOx is nitrous oxide; and VOC is volatile organic compounds. Did I get those right?

Inês Azevedo: You got it.

Daniel Raimi: Okay, cool. You have already touched on this in your answer to that previous question, but can you talk more about which fuel or fuels are most responsible for these health effects and about whether most of the damages affect people who live close to the power plants or further away?

Inês Azevedo: Coal is associated with the overwhelming majority of premature deaths in the power sector. Coal power plants constitute 90 percent of premature deaths from air pollution from electricity production. The damages from air pollution will often affect people that live very far away from where the emissions occur. For example, the bulk of the damages from air pollution that occurred in Pennsylvania or Ohio will come from other states rather than from emissions in those states. At the same time, the emissions from Pennsylvania and Ohio power plants are among the ones that have the largest impact in other states. So indeed geography matters.

Daniel Raimi: Yeah, that's fascinating. There is another study that you coauthored that estimates the climate and health benefits of reducing US power sector emissions by 30 percent. Can you talk a little bit about what you found in terms of the quantitative benefits of those emissions reductions? 30 percent relative to 2015 levels, perhaps, but you can correct me if I'm wrong and if you'd also talk a bit about how sensitive the results are to some of the key assumptions that go into producing estimates like social cost of carbon or the value of a statistical life?

Inês Azevedo: I'll be happy to. I'll mention again that this is a neat collaborative effort that was led by my former PhD students, Dr. Brian Sergi, who is now at the National Renewable Energy Laboratory. We had the opportunity to also work with Peter Adams, Nick Muller, Alan Robinson, Steve Davis, and Julian Marshall on this work.

What we did was characterize the electricity generating units across the United States in terms of their costs, greenhouse gas emissions, and their pollutant emissions. And then we asked the question of which plants would need to get removed or retired from the system and which generation they would need to be replaced with to achieve a goal of reducing greenhouse gas emissions by 30 percent. Importantly, we also tracked the health co-benefits that would arise from removing these plants from the system, which are often not only high greenhouse gas emitters but also high air pollutant emitters.

What did we find? First, in terms of the climate benefits, when we assume a social cost of carbon of $40 per ton of CO₂, the 30 percent emissions reduction goal would lead to 17 billion annually in reduced climate damages. To your point about the social cost of carbon value and how that affects the conclusions, this figure would change directly proportionately to the social cost of carbon assumed. Our results are very sensitive to the climate damages on our assumptions for the social cost of carbon.

In addition to the reduction in climate damages that directly emerges from the climate policy, we estimated the reduction in health damages from air pollution and found that health damages would be reduced between 21 and 68 billion per year. This would correspond to between 2,300 and 7,500 lives saved per year in terms of premature mortality avoided.

This means that the co-benefits from air pollution can be higher in magnitude than the benefit from reducing the climate change damages. Of course, this depends on a wide range of assumptions: the range itself that we found for the air pollution reduction benefits is quite wide, and that depends on several assumptions and certainties. The main one is the dose-response function: how do we relate the effects to health associated with an increase in PM2.5 concentration? Other uncertainties, doubts, and assumptions that will influence the range in our results include the type of air quality model used.

We tested the use of three reduced-form air quality models that have been developed by colleagues—and many of them, coauthors—in the study. That has an effect, but less so than the assumption on the dose-response function.

Of course, the value of a statistical life would also play a role, but in the results that I'm quoting here, we assume the EPA recommended value of $7.4 million in 2006 dollars. We updated it to $9 million in 2017 dollars.

Daniel Raimi: Really interesting. A couple of things you mentioned ring bells for previous episodes. We actually had Nick Muller on the show, who was one of your coauthors on this study and designed one of those reduced-form air transport models that you mentioned. If people want to bone up on the value of a statistical life, we did a whole episode on that with Alan Krupnick about 18 months ago. So, two really fascinating people talking about those topics if you want to dig more deeply into them.

Let's turn now to another topic that you've done a lot of work on, which is energy efficiency. Energy efficiency is going to play an enormous role in reducing emissions across the power sector and across the economy, more broadly, an then that has effects on the power sector. There are sometimes debates within the economics community about the cost-effectiveness of some energy efficiency programs like the Weatherization Assistance Program and trying to figure out which policies get us the best bang-for-the-buck in terms of emissions reductions.

As someone who's looked broadly across the energy efficiency space, from your perspective, what are some of the key lessons from the research on energy efficiency? What more do we need to know to make smart policy decisions?

Inês Azevedo: We've produced a recent review paper on what we have learned from energy efficiency research in the last 40 years. This was a piece that was coauthored with many colleagues and co-led by Harry Saunders and Joyashree Roy.

I guess some of the key messages are that energy efficiency has a very important role to play. We do know that we can make use of more efficient end-use technologies in the residential and commercial sectors all the way from more efficient lighting and transition to LEDs, to more efficient other end-use equipment, so the potential for savings is there. In some instances, those would be decisions that are cost-effective to consumers when you look immediately at the numbers, but things get a bit muddled in terms of how people make decisions and which of those decisions are realistically feasible in the current settings. I would say that the role is important, but the expectation that we would achieve something like full decarbonization via energy efficiency would be highly misleading, but it’s still a large contribution.

Every so often, concerns about rebound effects also arise as part of the discussion on energy efficiency. I wouldn't say there is a consensus on the role of the rebound effect. Discussions that emerge are generally very fierce. But at the level of the direct rebound effects, meaning you really increase the use of the same device or end-use because you have a more efficient one, such as switching from incandescent light bulbs to LEDs, would have a very minor effect, if at all. Or, traveling many more miles as you switch to a more efficient vehicle because you're saving on gasoline—that may not be a very important effect.

The indirect rebound effect in terms of shifts in your patterns of consumption from one thing to another, given that you have an additional budget to spend when you invest in energy-efficient, cost-effective strategies, is much more certain, and likely, a little bigger than the direct rebound effect, but still not something that I would be too concerned about.

Now, the overall economy-wide rebound effects are a whole other deal. I do think more research is needed to understand the implications of such. Those are the implications of large structural changes that come, which is the decrease in energy intensity for energy use. What does that do to prices and the overall new equilibrium that results from such? I think a lot of interesting research could emerge from there to understand better all those indirect effects and the resulting equilibrium. But energy efficiency would still have a very important role to play in decarbonizing our systems.

Daniel Raimi: That's really interesting. I had not thought much about the issue of the economy-wide rebound effect, but the indirect rebound effect makes sense.

Just to make sure I'm understanding you, let's imagine I buy a fuel-efficient car, which means I spend less on gasoline, so I have more money to drive out to my favorite steak house and eat a big steak, which has a big carbon footprint as well. Is that right for the indirect rebound effect?

Inês Azevedo: That's a lovely example. Yes, that's right on.

Daniel Raimi: Okay. That's the indirect rebound effect.

The economy-wide rebound effect, I imagine, is the kind of things where you would need a computable generalizable equilibrium model—a CGE model—that some economists have developed to try to answer those questions about how everything sloshes around in the entire economy. Does that sound about right?

Inês Azevedo: Yeah, that's right on.

Daniel Raimi: Okay, great. Well, we are getting close to the end of time, but I have two more questions that I'd love to ask you before we go to our Top of the Stack segment.

The first one is a question about the attention that we as a society give to greenhouse gas emissions versus so-called conventional air pollutants like PM2.5. There's so much discussion about climate change, and rightly so—it's an enormous challenge—but I feel we hear less in the popular conversation and in the media about the day-to-day health effects of particulate matter, which really causes the most immediate damages, and also, as you found in your analysis, could actually be more significant than the risks of climate change. Why do you think that is?

Inês Azevedo: I think as you pointed out, climate change has been at the forefront of the discussions in the media and in the policy realm. We do need to tackle this massive challenge of getting to decarbonized energy systems, so attention is important and required.

Until recently, there was not so much data, methods, and frameworks to understand the damages from air pollution to the scale that we've seen in recent years. There was a lot of model development in the last decade funded by the national agencies—in the case of the United States—that now allows us to really have a better understanding of the magnitude of the problem, so very much in the vein of the integrated assessment models that were developed to understand climate impacts and costs of mitigation, as well as costs of inaction. Now there's a suite of integrated assessment models for air quality. You just mentioned the podcast involving Nick Muller, who has developed some of those, as well as some of the coauthors of the previous work that I mentioned here. I think highlighting the fact that these co-benefits may be in the same order of magnitude, or sometimes even higher than the range of benefits from climate change, is really an important first step to bring attention to this issue. The really good news is that those co-benefits are there. The key point that I would like to highlight is that you can have even larger benefits by tackling climate change and air pollution damages together rather than in isolation. The cost of doing so increases by just a little bit, and less so than the benefits. So the net benefits for considering those policies jointly are much larger.

Daniel Raimi: Right. It's interesting how the two issues are so closely connected, and yet receive different amounts of attention. It's nice that the scales are being balanced, in part because of the great work that you and your coauthors have been doing.

Just one more question before we go to our Top of the Stack segment. I know you've been spending some time in Europe, and you've just returned to California fairly recently. I'm curious to hear what you've been working on: I know you have 700 things you're trying to do at once. Can you tell us about some of the things that are getting you most excited these days?

Inês Azevedo: Sure. The research on quantifying distributional effects and the environmental justice aspects of energy systems and sustainable transitions are really the things that are driving the bulk of my research, and the research of my students who are doing this incredible work.

Two examples of work that we're hoping to wrap up soon relate to the transportation sector. The question here is, as we electrify transportation, who are the winners and the losers?

Thinking about different dimensions, the first one is that you may remove vehicles from densely populated city areas, and so you're improving the air quality in those locations, while at the same time, if you're in a region in the Midwest or in India—which is our other case study, currently—you are going to be powering those electric vehicles with coal power plants. In the case of India, the coal power plants don't have air pollution control technologies. You’d be naturally increasing the damages to health, so there are clear trade-offs there.

Yet another dimension is the issue of affordability for those vehicles: who the adopters are versus who bears the consequences from the changes in air pollution or electricity rate increases. That stream of work and, in particular, this focus on contrasting the situation in India with the situation in the United States is a set of results that I'm very excited about.

Daniel Raimi: That's so interesting. I can't wait to see them. Is it under review right now? Or are you still in the research phase?

Inês Azevedo: Still preparing for review and hopefully submitting very soon.

Daniel Raimi: Well, I know how that goes. Good luck finishing it all up. And then of course, getting friendly and helpful reviewers along the way.

Inês Azevedo: Thank you so much.

Daniel Raimi: Let's go now, Inês, to our Top of the Stack question where we ask you to recommend something that you've read or watched or heard lately that you think our listeners would enjoy. And I'll start with a recommendation that features our fantastic producer, Elizabeth Wason.

Elizabeth edits and oversees all the publications on our Resources magazine webpage as well as the physical copy of the magazine that goes out every few months. There's been an enormous number of really great blog posts that Elizabeth has been editing, and getting up onto the resources.org webpage, there's really great stuff on fuel economy standards, the clean electricity performance program—which is in the middle of reconciliation discussions—machine learning and energy savings, and smart thermostats. There's just a ton of great content on there. If you have five minutes and you want to learn something really interesting about a wide range of energy and environmental topics, I'd just encourage you to check out resources.org. But how about you, Inês? What's on the top of your stack?

Inês Azevedo: I think in these times, humor is really welcomed. My suggestion will be something fairly light, but also important. Several late night show hosts have coordinated a few days ago or weeks, depending on when the podcast goes up.

Daniel Raimi: This podcast, just so people know we're recording this on September 30th and it'll probably air in a couple of weeks. So it'll probably be two or three weeks ago, by the time you are hearing this.

Inês Azevedo: So by then hopefully most of the listeners haven't missed that, but several late show hosts coordinated to talk about climate change, and that was lovely to see. So, just watching those all across the board would be my light suggestion for this podcast.

Daniel Raimi: That's great. I actually haven't watched that myself and really need to check it out. Thank you very much for that recommendation, and thank you again so much for coming on Resources Radio, telling us about the wide range of research that you carry out, and helping us understand it. We really appreciate it.

Inês Azevedo: Thank you so much. This was such a pleasure.

Daniel Raimi: You've been listening to Resources Radio. Learn how to support Resources for the Future at rff.org/support. If you have a minute, we'd really appreciate you leaving us a rating or a comment on your podcast platform of choice. Also, feel free to send us your suggestions for future episodes. Resources Radio is a podcast from Resources for the Future. RFF is an independent, nonprofit research institution in Washington, DC. Our mission is to improve environmental, energy, and natural resource decisions through impartial economic research and policy engagement.

The views expressed on this podcast are solely those of the podcast guests and may differ from those of RFF experts, its officers, or its directors. RFF does not take positions on specific legislative proposals. Resources Radio is produced by Elizabeth Wason with music by me, Daniel Raimi. Join us next week for another episode.