Toxic Metals Persist in Residents’ Bodies Up to 18 Months After Maui Wildfires

A new study finds that toxic metals from the 2023 Maui wildfires persisted in people’s bodies for up to a year and a half after the fires stopped burning, raising questions about how long communities should monitor air quality after a disaster.

A study published in Proceedings of the National Academy of Sciences examined the urine of 1,400 adults dwelling close to the burned regions. The investigation uncovered markedly higher levels of several metals, including arsenic, cadmium, copper and antimony. These substances tend to originate from burned structures, automobiles, electronic devices and other items, instead of merely the scorched plants that are usually the focus of such post-fire analysis.

The research connects those metal levels to actual health consequences. Individuals carrying larger amounts of these metals in their bodies tended to show abnormal lung function, including a reduced ability to take in breath and trouble moving air in and out of their lungs.

What the Maui Wildfire Exposure Study Found

One of the largest postfire investigations in the country, the Maui Wildfire Exposure Study, gathered urine samples from 1,400 adults. Scientists then measured their metal levels and contrasted them with national biomonitoring data, uncovering several notable discrepancies.

These effects followed the path where smoke and ash landed, matching up with specific places on the ground. Those living closest to Lāhainā, Wailuku and Kahului felt a distinct effect, separate from what people near Kula endured.

Alika Maunakea, who serves as a co-principal investigator for MauiWES and teaches anatomy, biochemistry and physiology at the University of Hawai’i, Mānoa, framed the results within a broader perspective.

“What we’re dealing with, especially in the aftermath of what we experienced in Lāhainā, is a much more complicated mixture of these chemical exposures.”

Why Long-Term Monitoring Matters

The fires that destroyed Lāhainā in August 2023 were among the deadliest in U.S. history. Caused by wind spreading a brushfire spurred by downed power lines, they killed more than 100 people and destroyed the town.

STAT’s study suggests that major wildfires, which are worsening with the planet’s warming, carry risks that last well past the flames themselves. Beyond the immediate danger of smoke, there is evidence that contaminated soot, residue and dirt may persist long after burning stops. This means post-wildfire air quality should be watched for a longer period than has been common. Recovery efforts need to account for what remains behind.

Professor Ruben Juarez, who is also co-principal investigator of MauiWES, argued for keeping up the focus.

“It’s really important to identify potential sources of these exposures and to mitigate and reduce potential risks for re-exposures that might be contributing to these effects.”

“What happens to the land and environment can shape what people breathe, take into their bodies, and develop over time. The consequences of that can unfold over many years.”

The scientists acknowledged that the research could not determine precisely how much of the effect stemmed directly from the wildfires as opposed to ongoing or other exposures, including Hawai’i’s geology, diet, past farming and manufacturing activity, and environmental sources. No comparable data exists for comparison with what came before August 2023.

How Climate Change Shapes Fire

Certain regions of the planet are seeing wildfires grow bigger, burn with greater intensity, move faster and strike more often, according to experts. This trend has been tied to rising temperatures and drier conditions associated with climate change.

In recent years, human-caused climate change has raised the odds of many large fires around the world and pushed fires into regions that rarely see them. The study authors cite earlier work showing serious long-term human effects from wildfires and other environmental crises, including lung problems and mental health issues such as depression.

“This is bigger than wildfires,” Juarez said. “These climate-related disasters can change the environment in ways that continue after the immediate emergency is over.”

Floods, hurricanes, fires and other disasters were among the events he noted, saying they “definitely can disturb soil, debris, buildings, and legacy contaminants that we have in Hawai’i, creating these pathways for exposure.”.

“Disaster response should not stop when visible danger is gone.”

What Health Experts Are Saying

The study has expanded our understanding of the health burden of the fires over an extended period, according to Kekoa Taparra, a physician and assistant professor who studies chronic diseases at the University of California, Los Angeles.

“This type of work echoes that climate-related disasters affect human health well beyond the immediate injuries and deaths we see during the event itself,” Taparra said. He was not involved in the study but has studied the health impacts of disasters.

Historic wildfires in Lāhainā and even Los Angeles were cited by Taparra, who noted that such disasters can produce longer-lasting consequences through displacement, disruption of healthcare and social networks, environmental exposures and potentially increased mortality.

“As these events become more frequent and severe, understanding and measuring their full health impact will be essential to building more resilient communities and health systems,” he said.

The Road Ahead

Planners working on recovery face a real question about how long to keep watching for harmful metals. The research shows that these metals can stay inside people’s bodies for more than a year and a half after coming from burned buildings and electronics.

What stays behind matters just as much as what is lost, according to the study. After the fire has passed, the soil, soot and debris hold traces that recovery work must take into account.

The research offers a wider warning about disasters tied to climate change. Such calamities as floods, hurricanes and fires can upset soil, ruin buildings and expose old pollutants, opening up paths for harm that endure long after the disaster itself has passed.

The consequences of that can unfold over many years.

Source material: “Risk from toxic metals can persist months after wildfires, Maui study finds,” STAT.

air quality · climate disasters · health study · toxic metals · wildfires