The burning of fossil fuels — coal, oil and gas — creates pollution that not only can harm health but also foster climate change. Together these impacts pose an outsize risk to children, studies show. Their data point to a growing need for society to better protect kids. That’s the conclusion of a new report.

It was prepared by Frederica Perera. She is a leading expert on health at Columbia University, in New York City, where she runs the Columbia Center for Children’s Environmental Health. She and her colleagues have been studying the health effects of pollution and stress. Their findings have shown, again and again, that both can produce measurable harm to children.

Youngsters who live in poor households and those of color tend to face an especially high risk of breathing polluted air and encountering stress, her team has shown. What kind of stress? It might be the anxiety of not always having enough food to eat. Stress also can develop when children must move because their parents have lost their homes or jobs. Or it can develop in any number of other ways.

Perera’s new report is what’s known as a review paper. It goes beyond her own work to bring together related findings from research teams around the world.

Journals often commission review papers to investigate — and then highlight — emerging trends that may not be obvious from reading only one or two studies. The data highlighted in a review paper may not be brand new. The trends it describes, however, can be. Moreover, examining work from many research teams may strengthen — or weaken — associations that link a cause to particular effects in just a few studies.

For her new review, Perera drew from roughly seven dozen papers and reports. Most were published during the past 10 years. The assessment that she wove from them was published June 21 in Environmental Health Perspectives.

Children under age five make up only 10 percent of the world’s population, the paper notes. But they suffer an estimated 40 percent of all environment-linked disease. That’s according to the World Health Organization, or WHO, which is a part of the United Nations. What’s more, WHO reports, children are affected by about 88 percent of the diseases that have been linked to climate change. Poor children — living in both rich countries and poor ones — suffer most, Perera notes.

Kids have not been enough of a focus, Perera tells Science News for Students. That is true, she says, “even though children suffer most of the impacts from environmental pollution and also from climate change.”

Government leaders and health experts have discussed climate change and the health impacts of these pollutants in the past, she notes. But those conversations have usually talked about each pollutant separately. Given their impacts, she says, “They should be considered as a whole.”

Why children face special risks

The burning of fossil fuels by vehicles, power plants, factories and even homes spews particles and gases into the air. The people most vulnerable from breathing them tend to be the youngest, Perera argues — children.

Here’s why. The immune system helps defend the body against infections and poisons, such as toxic chemicals. But in infants and children, the immune system has not yet finished developing. This means that the body is not fully protected from impacts such as breathing irritating or toxic pollutants, Perera explains.

Not surprisingly, studies have shown that fossil-fuel pollutants, including hydrocarbon compounds, can impair health. They can even affect a child’s brain.

“Air pollution is a risk factor for various developmental delays,” Perera points out. By this she means that children exposed to this pollution may learn more slowly. They also may struggle to cope with stress. Pollution exposures may even lower a child’s IQ or lead to attention deficit hyperactivity disorder. Taken together, these impacts can reduce a child’s ability to learn and to do well in school, she says.

One thing that makes a child’s brain so sensitive is that it is growing and changing rapidly. If a pollutant hits cells when it’s time for them to morph into something new, they might not do so correctly. Or they might not change on time.

A trio of studies from Europe, California and China found evidence this might be happening. They linked air pollution with the risk that babies would be born too soon and underweight. Babies that enter the world prematurely often are not fully developed. That ups their risk of disease and death. Babies born too small can face a lifelong elevated risk of health impacts. Such risks include heart disease.

The brain directs the activities of cells and organs throughout the body. So messing up its wiring when it is developing could change how almost any part of the body might function. That’s why early-life exposures to pollution are so risky, notes Perera. Indeed, she points out, one of her team’s 2009 studies showed that air pollution can harm a child even before it’s born. Babies whose moms breathed in large amounts of urban air pollution during pregnancy tended to score lower on IQ tests.

Older children also can face risks from inhaling these pollutants. One Spanish study published in April, for instance, linked exposure to air pollution from traffic with behavior problems and with learning difficulties.

Then there are pollution’s effects on the lungs. Studies show that inhaling fossil-fuel pollution can cause or worsen childhood breathing diseases. These include asthma and bronchitis. The science of how that can happen is known. But relatively new data now show that this asthma is affecting a greater share of American children than adults. That’s according to the U.S. Centers for Disease Control and Prevention, or CDC.

And asthma, a condition that makes it hard to fully inhale, is not just a U.S. problem. Asthma has been increasing in prevalence. Today, it is at an all-time high worldwide. In fact, it has become the most common non-infectious disease among children anywhere, reports WHO.

“Lifetime exposure to pollution begins in childhood,” says Patrick Kinney. He’s an environmental health scientist, also at Columbia. He is especially concerned about a child’s exposure to motor-vehicle exhaust. Those pollutants spew into “the street near people,” directly where they breathe, he notes.

Other costs of this pollution on climate and health

Fossil-fuel burning contributes to the build-up of carbon dioxide. It’s one of the so-called greenhouse gases. In the atmosphere, this CO2 can trap the sun’s heat, leading to global warming. A number of recent studies have linked hotter air temperatures to an increase in diseases of the lungs and heart. But global warming also is boosting the spread of some infectious diseases. These range from malaria to chikungunya.

Kinney says it’s important to remember that fossil-fuel emissions contribute to both illness and climate change, and that children are having these health problems now. Warmer temperatures help transform fossil-fuel pollution into smoggy ozone. Inhaling ozone can irritate the lungs. In some people, it can even cause trouble breathing, especially for children with asthma.

Earth’s rising temperatures have also been triggering an increase in extreme weather. These droughts, intense storms, flooding and wildfires can pose their own serious health impacts. They can damage homes, for instance. They can uproot families. Sometimes their impacts lead to food shortages. Taken together, these threats can lead to sickness, injuries and anxiety. And once again, children tend to suffer most from these events. The brain and mental-health problems that kids suffer may “play out over the whole life of the child,” Perera observes.

Her review paper also notes the high financial cost of health problems that can trace to fossil-fuel burning. She cited a 2015 WHO report citing health costs of urban air pollution in Europe alone at an estimated $1.6 trillion. Those costs, it noted, were for premature deaths and disease in just one year: 2010. By now, yearly costs are likely much higher. Stopping such pollutant emissions would cut those health-care costs enormously, writes Perera.

Understanding these impacts of pollution and climate change is important for doctors, especially those treating children, says Perry Sheffield. She is a pediatrician at Mount Sinai Hospital’s Icahn School of Medicine. It’s in New York City. “As our climate is now changing, doctors and nurses have an added role to play,” she says. They will have to help people understand that old risks — heat waves, pollution alerts and mosquito bites — may all become riskier in a warmer world.

The science, Perera concludes, indicates strongly that getting energy from sources other than fossil-fuel burning may provide huge benefits to health and the environment. Already, her review notes, there are powerful scientific and economic reasons for reducing the burning of fossil fuels — or at least the pollutants due to burning fossil fuels. A prime motivation, her report says, should be protecting society’s most vulnerable group — children.