Canadian wildfire smoke worsened pediatric asthma in US NE

First study of wildfire smoke’s effects on children with asthma in the Northeast reveals growing health risks for the region as climate change fuels more smoke-filled summers.

News Release 11-Dec-2025

Peer-Reviewed Publication

University of Vermont

New research from the University of Vermont reveals exposure to smoke from Canadian wildfires in the summer of 2023 led to worsening asthma symptoms in children in Vermont and upstate New York. 

The study, published today [12/11] in the journal Environmental Health, is the first to examine the relationship between wildfire smoke and asthma in the Northeast—which in recent years has seen a marked increase in poor air quality days due to wildfires. 

“In 2023 when we couldn’t see New York across the lake, a lot of Vermonters began to worry about wildfire smoke,” says Anna Maassel, a Ph.D. candidate at the Rubenstein School of Environment and Natural Resources, graduate fellow at the Gund Institute for Environment, and lead author of the paper. “A lot of people think of Vermont as a relatively safe place to live when it comes to climate change, but we found that smoke coming from hundreds of miles away affected children here.” 

Wildfire smoke contains tiny particles known as PM2.5, along with other toxic pollutants that can damage the lungs and worsen respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). 

Nationwide, 6.5% of children and 8% of adults have asthma. Vermont’s rates are higher with 7% of children and 11% of adults diagnosed with the disease. 

To assess if wildfire smoke from 2023 affected children in the area, the researchers accessed electronic health records for about 900 youth, ages 3-21, who were receiving treatment for asthma in Vermont and upstate New York through University of Vermont Health.  

The team analyzed three different clinical measures that assess how well-controlled a patient’s asthma is for the summers of 2022-2024. Then, they overlaid air quality data onto the region and estimated smoke exposure within each zip code. 

Compared with the relatively smoke-free summer of 2022, children’s asthma was significantly less controlled during the smoke-heavy summer of 2023, when plumes from Quebec blanketed the region. 

“In the summer of 2023, my pediatric pulmonology team received a high volume of phone calls from concerned parents saying, ‘My child is having trouble with asthma symptoms,” says Dr. Keith Robinson, a pediatric lung doctor at Golisano Children’s Hospital at UVM and co-author of the paper.  

The researchers didn’t find the same signal when they compared 2023 with 2024, which was surprising, and the team hopes future research could shed light on why. Still, Robinson says it’s clear that wildfire smoke is affecting Vermont’s youth.  

“I think our findings suggest that there is potential for wildfire smoke, even hundreds of miles away, to impact a child's health,” he says.  

Across the country, pollution from wildfire smoke is increasing. A study published earlier this year estimated climate change is projected to exacerbate the problem, leading to roughly 70,000 premature deaths each year by 2050. Without action, wildfire smoke could become one of the country’s worst climate disasters, the authors write.  

Robinson says there are steps clinicians can take to help families reduce exposure to wildfire smoke, including closing windows, avoiding outdoor activities and using air purifiers when air quality is poor.  

“Clinicians need to make sure that parents and patients understand how to check for air quality, especially when there are wildfires in the area,” he says. “We also need to make sure that patients and families who do not have the means to mitigate the effects of wildfire smoke have support from public health agencies.” 

The study was funded by UVM’s Planetary Health Initiative and brought researchers together from across UVM, the Robert Larner M.D. College of Medicine and UVM Health.  

“When you’re able to work with researchers that have a different area of expertise, it brings the impact to another level.  Personally, I learned a lot from my teammates about climate change and environmental health.  This project demonstrates the impact of collaboration across UVM departments,” Robinson said.   

The research also reflects the university’s commitment to Vermont.  

“This study is another example of how UVM researchers can engage with our state and our region to connect the dots between climate change and human health,” said Taylor Ricketts, director of UVM’s Gund Institute for Environment and co-author of the paper. “Understanding emerging threats to children’s health is a first step toward anticipating and reducing them.”  

The research team also included: Paige Brochu, a research assistant professor in the Rubenstein School, director of UVM’s Spatial Analysis Laboratory and a Gund Institute affiliate; Valerie Harder, with the Vermont Child Health Improvement Program and a professor in the Department of Pediatrics at the Larner College of Medicine; and Dr. Stephen Teach, a pediatric emergency medicine physician at University of Vermont Health and the Larner College of Medicine.