We’re all susceptible to environmental risks—but many of us don’t realize the ways that children are particularly vulnerable. In this edition of Author Talks, McKinsey Global Publishing’s Lucia Rahilly talks with pediatrician Debra Hendrickson, clinical professor at the University of Nevada, Reno, School of Medicine, about The Air They Breathe: A Pediatrician on the Frontlines of Climate Change (Simon & Schuster, July 2024). Hendrickson illuminates how our climate is causing often-unseen harm to our children’s physical and emotional well-being—affecting brain development, respiratory health, emotional wellness, and other areas that can change the long-term trajectory of their lives. An edited version of the conversation follows, or watch the full video at the end of this page.
So much has been published on climate. Why did you feel compelled to write this book?
The book began with a moment in my clinic when a mother brought a ten-month-old baby into my office during a smoke crisis. The baby’s mother used a damp baby blanket to try to protect her from the smoke, yet the blanket was just covered with ash. There was an apocalyptic scene outside, where ash was falling from the sky like snow, swirling around the building in huge gusts of wind. When I listened to the little baby’s lungs, she looked up at me. She was struggling to breathe.
Over the past decade, we have had worsening megafires, enormous wildfires, in the Sierra Nevada mountains—right outside my windows—that have left Reno just socked in with smoke for months at a time. The Yosemite Rim fire was the first one of these that signaled to us that something was really changing.
The juxtaposition of what’s happening in the world and this one little baby coming into a pediatrician’s office felt like a punch to the chest. That was really the impetus for the book.
For many years, climate scientists and climate activists had been invoking children in their arguments. There was the concept that climate was the greatest moral crisis that humanity has ever faced, since every child on Earth will be affected by it. But those calls were not seen to move the needle much. Yet when I had that moment with that one baby, I thought that, to understand the depth and gravity of what’s happening and its emotional impact, people really need to see one child’s face and understand the effect on one child.
Why are kids more susceptible to environmental risk than the rest of us are?
For children, a lot of organs are not fully developed after birth. Their organs and physiological systems are still forming. What happens in the environment around children shapes certain organs.
For example, the quality of the air kids breathe affects the growth and function of the lungs. Studies have been completed of kids in Southern California who were raised for decades in poor-quality air. These kids actually had stunted lungs, or poor lung function.
Another example is the brain. The brain is constantly interacting with the outside world, with parents, and with the environment. And we now know that air pollution causes brain damage in children. Air pollution is contributing to rates of autism, ADHD [attention deficit hyperactivity disorder], and learning disabilities in children. The trauma of natural disasters—drought, famine, and flooding—that children endure will have a big effect on them as well.
Air pollution is contributing to rates of autism, ADHD [attention deficit hyperactivity disorder], and learning disabilities in children. The trauma of natural disasters—drought, famine, and flooding—that children endure will have a big effect on them as well.
You mentioned poor-quality air. Say more about how rising air pollution affects kids.
Air pollution affects every system in the body. The two types of air pollution I focus on in the book, particulate matter and ozone, are two that we know are increasing because of climate change. Particulate matter is rising largely because of wildfires. Wildfire particulates have skyrocketed across the Western United States. Tens of millions of people are exposed to them every year. These very fine particles that are especially prevalent in megafire smoke can be bound to toxic chemicals, and they can penetrate deeply into the body. They don’t just affect the lungs. They affect the growth of the lungs and the function of the lungs, causing wheezing, asthma, and respiratory problems.
They penetrate the blood stream and affect the brain, the kidneys—every part of the body—and cause myriad health impacts. Even prenatally, the particles that pregnant mothers breathe in go through the placenta and through the bloodstream and can seed into the baby’s brain.
Babies whose mothers have been exposed to high levels of particle pollution during the pregnancy experience higher rates of autism. There’s a recent study of 300,000 kids in Southern California that showed a strong, significant link between particle pollution and autism in the infants of these mothers.
When children inhale particles through the nose, those particles seed the frontal lobe. You can see them on autopsies of the deceased. And on imaging, you can see that they’re actually affecting the cognitive function of live kids.
As someone who spends a lot of time speaking with parents about autism, vaccine risks, and other concerns that parents have, this impact has completely escaped public attention. There’s a growing body of evidence that particles themselves and the chemicals adhered to them are causing brain damage and dysfunction in children.
What about the second type of air pollution, ozone? Isn’t ozone a good thing?
Good ozone is the layer above the Earth that protects us from ultraviolet radiation. Bad ozone is the type that is at ground level and is an air pollutant.
Ozone is very prevalent in cities because of the exhaust from all the fossil-fuel-burning machines and factories. When these pollutants combine with heat, they form ozone. It’s extremely irritating to the airways and can cause a lot of coughing and wheezing.
There’s some evidence that exposure to ozone increases the incidence of asthma in exposed children. Those who play sports in high-ozone cities are more likely to develop asthma than kids who don’t are. It looks like it acts synergistically, as do particulates with allergies, with allergens—the allergen proteins are more able to penetrate and cause inflammation when also in the presence of these pollutants.
Ozone is a big health problem. When it rises in a city, you see school absences increase. It has a significant influence on kids’ respiratory health.
How are rising temperatures affecting kids?
I profiled two teenage boys who went on separate short hiking trips on summer days in Phoenix approximately one year apart. They both ended up suffering heat stroke. The key difference between their cases and how their stories turned out was the speed with which they were responded to and the medical attention they received. I use that as a metaphor for climate change and how quickly we’re responding to the threat that all children face.
Each boy was with an adult man who did not realize that the boy was getting into trouble when the adult was not. In the case involving Joey, he vomited, got dizzy, and felt light-headed. His father didn’t realize how much danger Joey was in. Joey collapsed, and people took him to the emergency room. He ended up spending the entire summer in the pediatric intensive care unit and barely survived.
The body has many mechanisms for coping with heat. The goal of the body is always to keep your internal organs at about 98.6°F. The body accomplishes that in different ways, starting with shunting blood to, and circulating it from, the skin. Sweating is another mechanism to achieve evaporative cooling off the skin, provided that one is drinking water to maintain blood volume, to get the blood to the skin, and to make sweat.
Since Joey wasn’t drinking enough that day, and the outside world began to exceed the temperature that enables the body to cool off, it became impossible to use those mechanisms to cool. That’s when people begin experiencing heat illness and heat stroke. The compensation mechanisms we have to maintain a constant internal temperature just start to fail.
Although the city is doing everything it can to try to adapt to and cope with those changes, at some point it will become almost impossible to go outside, to your car, or to work in temperatures that high.
Will we be able to acclimate to rising heat?
People can acclimate to a certain degree. It’s true that people who live in Phoenix full time are more acclimated to the heat than tourists are. I have some examples of tourists who came to the city and died of heat stroke during one hot weekend because they were just not acclimated to the heat in the way that locals are.
The two teenage hikers who experienced heat stroke were both Phoenix residents. Both were acclimated to the heat yet suffered from heat stroke nonetheless because there are physiological limits to what the human body can do. At some point, the proteins that make up the body just can’t function at certain levels of heat.
Will kids be able to play outside in a hotter future?
There are a lot of secondary effects to heat that are affecting children that we just don’t consider. For example, when it’s not safe to be outside, children spend more and more time indoors. Usually, that means spending time on devices, which means kids are getting heavier. That places them at higher risk of diabetes, depression, heart disease, all kinds of long-term chronic health problems, and mental health issues as well.
Kids do better when they’re outside in nature playing, running around. During childhood, summer used to be a time for getting out, going camping, playing sports, hanging out in the neighborhood. That kind of life for children is going to disappear if we don’t make dramatic changes to stop the warming of the world. It will be impossible to be safe outdoors during a lot of the summer.
Is climate risk already affecting kids’ mental health?
The climate crisis is having a big effect on mental health, especially that of teens.
There are a number of surveys now that have polled children of various ages around the world and have shown that climate change is a major concern weighing on children. While they may not always raise this issue at the pediatrician’s office or with their parents, it’s in the background of their lives—constantly. They know this change is happening. Basically, they’ve been handed what feels like the end of the world.
I have spent a lot of time in Houston. In one of the chapters of the book, I profiled a five-year-old boy whose home had been destroyed by Hurricane Harvey. I covered his retelling of what he and his mother had been through during the flood. His home was destroyed; they lost everything they had. He was also separated from his dad and showed signs of PTSD [posttraumatic stress disorder] months later that made him struggle significantly.
As natural disasters escalate and kids experience more of them, we will run the risk of negative emotional responses and mental health problems growing.
I interviewed a researcher who, at that time, specialized in trauma to children at Texas Children’s Hospital. We discussed the children who endure these events and how they respond to them. The response is influenced by how well their parents do and by how much trauma they underwent before in their lives. Their experiences during the flood—some examples include whether they witnessed injury or death, experienced separation from their parents, or lost their pet, home, or school—predicted more trouble later.
Overall, the big predictor for children’s response to these types of events is based on how much trauma they’ve had before. For example, the children of an impoverished family or a family that’s migrated and had some kind of trauma in the past would tend to be much more at risk than others would be.
One of the issues I raise in the book is that as natural disasters escalate and kids experience more of them, we will run the risk of negative emotional responses and mental health problems growing.
Even in the study conducted by this one researcher, it was revealed that one in five children had already survived another natural disaster because they were mostly from the Gulf Coast states. A lot of them had already survived a tornado or a hurricane prior to Hurricane Harvey.
Beyond people living in Gulf Coast states, are there other demographics at particularly acute risk?
One really critical aspect of the urban heat effect and the higher pollution in urban areas is their palpable effect on low-income kids and minority communities. We will likely see people arguing one of the big social questions we have had for generations: Why is there intergenerational persistence to poverty?
These children face greater risk because their low-income status makes them much less likely to have consistently functioning air conditioning. So the regulation of heat and availability of air filters, things to help with air pollution, will be affected by income, as well, placing minority communities at greater risk than everyone else.
Kids have just been through the COVID-19 pandemic. Does climate risk increase infectious disease risk, in general?
We think of infectious diseases in terms of which types of pathogens cause them and how they’re transmitted. The major types of pathogens are bacteria, viruses, and fungi. They’re passed to people through water, food, and air by vectors like mosquitoes and ticks.
Certain categories of pathogens are more affected by climate. Fungal infections are morphing and increasing and transforming more often from what are usually skin infections to more invasive infections. It appears that whole categories of pathogens will be affected in a bad way by climate change. The two big categories I focused on were what I call zoonotic diseases carried by animals and vector-borne diseases.
Zoonotic diseases account for most new infections in people—75 percent of the new pathogens we see. The cause is not just climate change but our disruption of the natural world and deforestation, which changes the types of animals, their migration, our contact with them, and our use of factory farming, which tends to cram livestock together. The main way that climate change affects those diseases is through migration and through the movement of certain types of animals. The combination of deforestation and climate change leads to more human contact with disease-carrying rodents and bats, those types of animals.
In terms of vector-borne diseases, mosquitoes are responsible for more illness and death than any other cause in the world. Mosquito-borne diseases are thought to have accounted for 52 billion deaths in the history of the world, which is about one-half of all the deaths ever—one-half of all the people who have ever lived. As most of those were babies and toddlers, that’s a big, big concern as the world warms. A lot of these vectors—especially certain disease-carrying mosquitoes, like Aedes aegypti—are expanding into more and more areas.
What should we be doing differently to safeguard the health of our children?
It’s always best to focus locally; that’s the best way to be effective. You can be involved much more easily in your own city or town than at a national level. For example, what’s powering the power that comes to your house? Is it gas? Is it coal? What’s that power company’s long-term plan for switching to renewable energy? How is electricity getting to your house? Do you have utility capacity in your community to deal with new renewable-energy projects coming online? How is the utility commission structuring rates to encourage renewable energy?
Consider that you’re in the center of a number of circles of activity. There are different domains that are contributing to what’s happening to prioritize those in terms of their biggest contribution and addressing them. See what you can do as an individual to address them.
You live in Reno; you use air conditioning; you drive. How do you reckon with your own energy use?
One of the things I mention in the book is that here in Reno, Nevada, and in a lot of states, you can elect an affordable green option for your electricity. A lot of people do not know about green options. I obtain all my electricity from renewable sources. I’m also fortunate to live in a state that has a lot of sun, wind, and geothermal energy.
If your utility has a green-energy program, switching is quick and easy. The rates vary and require investigation, but here, it’s a very affordable option. Also, for those who can afford it, rooftop solar panels are another option. This is not an all-or-nothing process by which we should judge ourselves harshly. Every little adjustment helps.
Every pound of carbon that we keep out of the atmosphere is something we’re doing for our children. With that in mind, we must try to do whatever we can to lower our own carbon footprint. We must also recognize that we’re part of a community. As we work on individual efforts, we can simultaneously work to address larger power plants, garbage dumps, and other factors so that they’re all moving in the right direction.
What surprised you most in writing this book?
The brain research was startling and upsetting. The effects are not harmful to children alone. Now even the rates of Alzheimer’s and other forms of dementia are thought to be linked to particle pollution. The lesions found in kids’ brains mimic those found in Alzheimer’s patients.
This information is very disturbing. But I’m hoping that it will motivate people more when they understand those links and how integrated children’s bodies are with the environment. We’re constantly interacting with the environment, and people must recognize that.
The effects are not harmful to children alone. Now even the rates of Alzheimer’s and other forms of dementia are thought to be linked to particle pollution.
The other surprising thing was speaking one-on-one with parents. I was worried about politics affecting how people reacted to what I was doing. I’m trying to leave politics more or less out of the book. I don’t think there’s any difference in the parents I deal with in terms of how their politics influences how much they love their children.
I hoped for this effort to be a unifying achievement. The idea is that this is something that does unite everyone: that we all care about our kids and the kind of world we’re leaving them. It was surprising and heartening that even though there were political differences among the parents, no one raised politics as an issue in what I was talking about or trying to do. They all cared, were worried, and wanted to do something.
Are you optimistic that we’ll leave a safe world for our children?
We’ve reached an odd moment: the best of times and the worst of times. We have every solution in front of us. We’re at the cusp of amazing findings in medicine and technology. We totally have the ability to solve this problem.
One sentence in the book states that we think of this as a global crisis, but it’s actually a very personal crisis multiplied many times. It’s a crisis for the people we love most, the children we hold in our arms and promise to keep safe.
We think of this as a global crisis, but it’s actually a very personal crisis multiplied many times. It’s a crisis for the people we love most, the children we hold in our arms and promise to keep safe.
There’s urgency. But we also have agency, as a lot of the climate scientists like to say. And we can’t just sit back and wait for somebody to solve this problem. Addressing this problem for our children must be an all-of-society effort. All of us have to attack it.
Watch the full interview
