The 2023 Maui wildfires, among the deadliest in U.S. history, destroyed Lāhainā and killed more than 100 people. A new study published in Proceedings of the National Academy of Sciences analyzed urine from 1,400 adults who took part in the Maui Wildfire Exposure Study, one of the largest post-fire investigations in the country. The researchers found substantially elevated concentrations of metals such as arsenic, cadmium, copper, and antimony up to a year and a half after the fires, likely from burned buildings, vehicles, and electronics rather than just vegetation.
Antimony levels were nearly 40 times higher than U.S. biomonitoring data, while manganese, barium, and arsenic were also elevated. Participants with higher metal levels were more likely to show abnormal lung function, such as reduced breathing capacity and difficulty moving air in and out of the lungs. These effects aligned with the geographic spread of smoke and ash, with residents near Lāhainā, Wailuku, and Kahului experiencing different impacts than those near Kula.
The researchers acknowledged a key limitation: without comparable data from before August 2023, they cannot determine exactly how much of the exposure came from the wildfires versus Hawaiʻi's geology, diet, or historical contamination. Still, they argue that disaster response should not stop when visible danger is gone, and that longer-term air quality monitoring is needed. As climate change makes wildfires more frequent and severe, the findings underscore that health consequences can persist well beyond the immediate emergency.