About . Birth before 37 weeks can lead to a cascade of health risks, both immediate and long-term, making prevention a vital tool for improving public health over generations.��

In recent years, researchers have identified a potential link between wildfire smoke — one of the fastest-growing sources of air pollution in the United States — and preterm birth, but no study has been big or broad enough to draw definitive conclusions. A new study led by the 91̽�� makes an important contribution, analyzing data from more than 20,000 births to find that pregnant people who are exposed to wildfire smoke are more likely to give birth prematurely.

“Preventing preterm birth really pays off with lasting benefits for future health,” said lead author , a 91̽��postdoctoral researcher in environmental and occupational health sciences. “It’s also something of a mystery. We don’t always understand why babies are born preterm, but we know that air pollution contributes to preterm births, and it makes sense that wildfire smoke would as well. This study underscores that wildfire smoke is inseparable from maternal and infant health.”

In the study, ,��researchers used data from the , a federal research project focused on how a wide range of environmental factors affect children’s health. The sample included 20,034 births from 2006-2020 across the contiguous United States.

Researchers estimated participants’ average daily exposure to fine particulate matter, or PM2.5, generated by wildfire smoke, and the total number of days they were exposed to any amount of smoke. They estimated the intensity of smoke exposure by how frequently participants were exposed to wildfire PM2.5 levels above certain thresholds.

They found that pregnant people exposed to more intense wildfire smoke were more likely to give birth prematurely. In mid-pregnancy, exposure to any smoke was associated with an elevated risk of preterm birth, with that risk peaking around the 21st week of gestation. In late pregnancy, elevated risk was most closely associated with exposure to high concentrations of wildfire PM2.5, above 10 micrograms per cubic meter.

“The second trimester is a period of pregnancy with the richest and most intense growth of the placenta, which itself is such an important part of fetal health, growth and development,” said co-author , a 91̽��professor of environmental and occupational health sciences and of pediatrics in the 91̽��School of Medicine. “So it may be that the wildfire smoke particles are really interfering with placental health. Some of them are so tiny that after inhalation they can actually get into the bloodstream and get delivered directly into the placenta or fetus.”��

The link was strongest and most precise in the Western U.S., where people were exposed to the highest concentrations of wildfire PM2.5 and the greatest number of high-intensity smoke days. Here, the odds of preterm birth increased with each additional microgram per cubic meter of average wildfire PM2.5.

It’s possible those results were more precise simply because the West experiences more wildfire smoke on average, making the exposure model perform better, Sherris said. But there may be other factors behind the regional differences.��

The composition of wildfire smoke is different across the country. In the West, smoke tends to come from fires nearby, while in places like the Midwest, smoke has typically drifted in from faraway fires. and reacts with sunlight and airborne chemicals, which could have affected the results. Researchers also noted that external factors like co-occurring heat or housing quality may have effects that aren’t fully understood.��

Researchers hope that future studies will examine the exact mechanisms by which wildfire smoke might trigger preterm birth. But in the meantime, Sherris said, evidence for a link is now strong enough to take action.��

“There are a couple avenues for change,” Sherris said. “First, people already get a lot of public health messaging and information throughout pregnancy, so there’s an opportunity to work with clinicians to provide tools for pregnant people to protect themselves during smoke events. Public health agencies’ messaging about wildfire smoke could also be tailored to pregnant people and highlight them as a vulnerable group.”

Co-authors include , doctoral student of environmental and occupational health sciences at the UW; , clinical associate professor of environmental and occupational health sciences at the UW; , professor of biostatistics at the UW; , associate professor of environmental and occupational health sciences and of epidemiology at the UW; , postdoctoral fellow of epidemiology at the UW; and , assistant professor of environmental and occupational health sciences at the UW. A full list of co-authors is included with the paper.

This research was funded by the Environmental influences on Child Health Outcomes (ECHO) program at the National Institutes of Health under multiple awards. A full list of ECHO funding awards is included with the paper.��

For more information or to contact the researchers, email Alden Woods at acwoods@uw.edu.

Asthma affects more than 6% of U.S. children, making it the most common chronic disease in kids nationwide. It’s difficult to isolate any single cause, but one of the most common contributors is air pollution: Studies have shown that breathing air with high levels of fine particulate matter, nitrogen dioxide and other environmental pollutants can increase children’s risk of developing asthma. But it’s been unclear whether long-term, early childhood exposure to ozone, the pollutant that most frequently exceeds U.S. air quality standards, contributes to the disease.����

, a doctoral student at the 91̽��, set out to find a possible link. In a study , Dearborn and collaborators identified a puzzling trend: Children exposed to higher levels of ozone in their first two years of life were significantly more likely to be diagnosed with asthma or wheezing at ages 4-6 — but researchers didn’t observe the increased risk of asthma at ages 8-9.����

While the researchers couldn’t pin down the exact reason, possible explanations include the changing nature of asthma as kids age, which could lead to a drop-off in formal diagnoses, and the influence of other risk factors and pollutants on asthma as children’s lungs grow.��

“It’s a puzzling finding,” said Dearborn, who led the research in the 91̽��Department of Environmental & Occupational Health Sciences. “It’s something we spent a long time trying to consider, and I don’t know if we ever came up with a satisfying answer. But these findings are important. Even if we only see the effects early in life,��there are still all kinds of associated health care costs and stresses for families. There are all sorts of larger contextual factors about having this chronic disease at any point in life.”��

This study relied on data from the (ECHO) program, a federal research project focused on how a wide range of environmental factors affect children’s health. Researchers drew 1,118 participants from six cities, including Seattle and Yakima, who had low-risk pregnancies and completed validated surveys that asked if their children had been diagnosed with asthma or had experienced wheezing.����

Researchers estimated exposure in the first two years of a child’s life using a model developed by co-author , a 91̽��professor of environmental and occupational health sciences, of epidemiology and of medicine. They found that a relatively small increase in ozone exposure — 2 parts per billion — in a child’s first two years of life was associated with a 31% increase in asthma and 30% increase in wheeze at age 4-6 years. Asthma and wheeze risk at ages 8-9 was not found to be associated with their early life ozone concentration.��

Researchers also analyzed how exposure to mixtures of three common air pollutants — ozone, nitrogen dioxide and fine particulate matter (PM2.5) — affected asthma outcomes. In this analysis, ozone stood out.��

“We interpret trends, and what we can conclude from this analysis is that when ozone within the air pollution mixture was higher than about 25 parts per billion, we saw a higher probability of asthma regardless of the concentration of nitrogen dioxide,” Dearborn said. “We found a relationship between ozone and asthma only when fine particulate matter was at or above median concentrations, giving novel evidence that the relationship between ozone and childhood asthma may depend on the concentration of other pollutants, like fine particulate matter.”��

The study’s findings highlight the need for more research into the effects of long-term ozone exposure in early life, Dearborn said. Further study could determine why the increased asthma risk related to ozone is not evident at ages 8-9, and whether it increases again later in childhood.����

In the meantime, Dearborn said, researchers and public health officials should pay more attention to the effects of long-term exposure to ozone.��

“In the United States, ozone regulations only consider a very short time period,” Dearborn said. “We don’t regulate ozone over the long term, and that’s where this analysis fits in. Maybe we should be considering both a short- and a long-term threshold for the regulation of ozone.”����

Other authors are , a 91̽��professor of environmental and occupational health sciences and of pediatrics in the 91̽��School of Medicine; postdoctoral researchers and , research scientist , and clinical associate professor , all of the 91̽��Department of Environmental & Occupational Health Sciences; , a 91̽��professor of biostatistics; , a graduate student in the 91̽��Department of Epidemiology; of Seattle Children’s Research Institute and an assistant professor of pediatrics in the 91̽��School of Medicine; Margaret Adgent and Paul Moore of Vanderbilt University Medical Center; Yu Ni of San Diego State University; Marnie Hazlehurst and Drew Day of Seattle Children’s Research Institute; Ruby Nguyen of the University of Minnesota; Kaja LeWinn of the University of California, San Francisco; and Kecia Carroll of the Icahn School of Medicine at Mount Sinai in New York City.����

This research was funded by the National Institutes of Health’s ECHO-PATHWAYS program; the National Center for Advancing Translational Health Sciences; the National Heart, Lung, and Blood Institute; the National Institute of Environmental Health Sciences; the 91̽��Pediatric and Reproductive Environmental Health Scholars K-12 program; the U.S. Environmental Protection Agency; the 91̽��EDGE Center; the National Institute on Aging; and the Urban Child Institute.��

Air pollution is not just a problem for lungs. Increasingly, research suggests air pollution can influence childhood behavioral problems and even IQ. A new study led by the 91̽�� has added evidence showing that both prenatal and postnatal exposure to air pollution can harm kids.

The study, , found that children whose mothers experienced higher nitrogen dioxide��(NO₂) exposure during pregnancy, particularly in the first and second trimester, were more likely to have behavioral problems.

Researchers also reported that higher exposures to small-particle air pollution (PM_2.5) when children were 2 to 4 years old was associated with poorer child behavioral functioning and cognitive performance.

“Even in cities like Seattle or San Francisco, which have a lot of traffic but where the pollution levels are still relatively low, we found that children with higher prenatal NO₂ exposure had more behavioral problems, especially with NO_2��exposure in the first and second trimester,” said , lead author and a postdoctoral scholar in the Department of Environmental & Occupational Health Sciences.

The study involved data gathered from 1,967 mothers recruited during pregnancy from six cities: Memphis, Tennessee; Minneapolis; Rochester, N.Y.; San Francisco; and two in Washington, Seattle and Yakima. Originally, these participants were enrolled as part of three separate studies: , and . The three studies have been combined under a major NIH initiative called ECHO, which brings together multiple pregnancy cohorts to address key child health concerns. These three combined cohorts are known as the consortium.

The study employed a state-of-the-art model of air pollution levels in the United States over time and space that was developed at the 91̽��. Using participant address information, the researchers were able to estimate each mother and child’s exposures during the pregnancy period and early childhood.

Exposure to NO₂ and PM_2.5 pollution in early life is important to understand, Ni said, because “there are known biological mechanisms that can link a mother’s inhalation of these pollutants to effects on placenta and fetal brain development.”

Furthermore, once the child is born, the first few years are a critical time of ongoing brain development as the number of neural connections explodes and the brain reaches 90% of its future adult size, the researchers write. For young children, inhaled pollutants that invade deep in the lung and enter the central nervous system can cause damage in areas relevant for behavioral and cognitive function.

“This study reinforces the unique vulnerability of children to air pollution — both in fetal life where major organ development and function occurs as well as into childhood when those processes continue. These early life perturbations can have lasting impacts on lifelong brain function. This study underscores the importance of air pollution as a preventable risk factor for healthy child neurodevelopment,” said senior author��Dr.��, a professor in the 91̽��School of Public Health and School of Medicine.

More specifically, the researchers found that exposure to PM_2.5 pollution was generally associated with more behavioral problems in girls than in boys, and that the adverse effect of PM_2.5 exposure in the second trimester on IQ was stronger in boys.

“We hope the evidence from this study will contribute to informed policymaking in the future,” Ni said. “In terms of reducing air pollution, the U.S. has gone a long way under the Clean Air Act, but there are threats to continued improvement in the nation’s air quality. The evidence suggests there is reason to bring the level of air pollution down even further as we better understand the vulnerability of pregnant women and children.”

Co-authors include Christine Loftus, Michael Young and Marnie Hazlehurst, 91̽��Department of Environmental and Occupational Health Sciences; Sheela Sathyanarayana, 91̽��School of Public Health and School of Medicine; Adam Szpiro, 91̽��Department of Biostatistics; Laura Murphy, Frances Tylavsky and W. Alex Mason, University of Tennessee; Kaja LeWinn and Nicole Bush, University of California San Francisco; and Emily Barrett, Rutgers University. This research was funded by the National Institutes of Health through the ECHO-PATHWAYS consortium.

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For more information, contact Yu Ni at niyu@uw.edu.

With evidence of the health hazards facing children from air pollution growing, The American Academy of Pediatrics on Monday meant to bring those hazards to light and to encourage and direct policy to improve children’s health.

Policy co-author Dr. , a professor in the 91̽��’s School of Public Health and School of Medicine, said because pediatric care providers are trusted advisers on healthy practices for prevention, they have an important role in getting the word out to families and policymakers that healthy air is part of the prescription for healthy children.

“Environmental health,” Karr added, “has not been a prominent part of medical education and training, and I hope the policy statement helps the pediatric community fulfill its role in ensuring healthy air for��all��children.”

In the policy statement, Karr and lead author Dr. Heather Brumberg, professor of pediatrics and clinical public health at New York Medical College, point out the connections between ambient air pollution and a range of associated health problems in children — asthma, preterm births, abnormal lung and neurodevelopment, pediatric cancer, obesity and risks of cardiovascular disease.

Conversely, the authors note how improvements in air quality, either nationally or regionally, have been associated with improved health outcomes for children. For example, they wrote that changes in public transportation use and reduced levels of air pollution during the “natural experiments” of the 1996 Olympics in Atlanta and 2008 Olympics in Beijing, were associated with children’s asthma improving and birth weights increasing, respectively.

“Interestingly,” they added, “when school buses in select Washington state communities used clear air technologies, participating elementary school students had both better lung function and less school absenteeism.”

For the authors’ complete discussion of the health hazards facing children due to ambient air pollution and their recommendations to pediatricians, check out the .

Below is a brief Q&A with Dr. Karr, who is also a professor in��the 91̽��Department of Environmental & Occupational Health Sciences, concerning air pollution and kids’ health.

91̽��News: Why it is important to understand the role pollution has on children’s health?

Karr: Children are more vulnerable by design. They take in more air on a per body size basis than adults, receiving higher doses of air pollution. Their organs are developing in form and functionality.��We now understand there are multiple potential types of health compromises in relation to air pollution exposure in early phases of development from fetal life and early childhood. These early life insults can have life-long consequences.

The toxic properties of air pollution are linked to most of the major chronic health problems facing children today — premature birth or low birth weight, respiratory infections and asthma exacerbations, even development of asthma, poorer cognitive development and risk of autism.

As seen for COVID, structural racism and economic disadvantage drive disproportionate effects of health threats. Air pollution, while ubiquitous, has unequal distribution of higher concentrations in communities of color and communities with increased poverty. If we are serious about addressing health disparities in children, we need to address air quality disparities.

91̽��News: Worldwide, national and even regional pollution can seem like a problem that’s too big for any one person to have an impact on — how can individuals make a difference?

Karr: Individual behaviors add up to influence community air quality. There are many everyday individual considerations that can make a difference. For example: Choose cleaner transportation and move away from gas powered motor vehicle trips. When you can, carpool or use public transportation and bike or walk whenever possible.��Also, avoid gasoline powered lawn equipment and avoid burning leaves, trash or other material. Compost leaves and yard waste.

Collectively, individuals can have an impact on broader policy and community practice. Join efforts to advocate for renewable energy, improved access to public transportation and safe siting of schools and daycares. Support increased focus on areas of enhanced vulnerability, including low-income communities, and air pollution sources that have been poorly addressed, such as agricultural production.

For more information, contact Dr. Karr at ckarr@uw.edu.

Two 91̽�� professors��have received the 2017 , the highest honor given by the U.S. government to early career scientists and engineers.

, associate professor of statistics and of computer science and engineering and Amazon Professor of Machine Learning, and , professor of pediatrics in the 91̽��School of Medicine and of environmental and occupational health sciences in the 91̽��School of Public Health, were among the 102 recipients announced by the White House this week.

Awardees are selected for their “pursuit of innovative research at the frontiers of science and technology and their commitment to community service as demonstrated through scientific leadership, public education or community outreach,” according to a .

Fox was nominated by the National Science Foundation “for her groundbreaking work in large-scale Bayesian modeling and computational approaches to time series and longitudinal data analysis, and for outstanding research and mentoring of women in computer science and statistics.”

Her machine learning research has been applied in a wide range of domains, including neuroscience, finance and econometrics, human motion and social networks. ��Some of her latest projects include analyzing functional connectivity networks in the brain from neuroimaging data, modeling highly localized house price indices in collaboration with Zillow and developing a novel statistical framework for analyzing sparse social network data.

Fox is also an adjunct associate professor of electrical engineering and a data science fellow of the eScience institute.

Karr, who was nominated by the U.S. Department of Health and Human Services, uses a community engaged approach to research focusing on environmental contaminants and pediatric respiratory health — including asthma, the health of farmworker children and global children’s environmental health.

Recent projects include working with Native American and Latino communities in the Yakima Valley to develop low-cost air pollution sensors aimed at reducing wood smoke exposure, conducting an intervention trial among Yakima youth with asthma to evaluate the effectiveness of home air cleaners and investigating how exposure to environmental factors from conception through early childhood influences the health of children and adolescents.

Karr, also an adjunct professor of epidemiology, directs the Northwest Pediatric Environmental Health Specialty Unit, a regional consultation and education service. She also cares for patients and teaches resident physicians at the Pediatric Care Center at 91̽��Medical Center-Roosevelt.

More than a dozen federal departments or agencies nominate young scientists and engineers from across the country whose “early accomplishments show the greatest promise for assuring America’s preeminence in science and engineering and contributing to the awarding agencies’ missions.” The final awards, first established by President Bill Clinton in 1996, are coordinated by the Office of Science and Technology Policy within the Executive Office of the President.

“I congratulate these outstanding scientists and engineers on their impactful work,” President Barack Obama said in a statement. “These innovators are working to help keep the United States on the cutting edge, showing that federal investments in science lead to advancements that expand our knowledge of the world around us and contribute to our economy.”