A study has shown that smoke generated by wildfires can pose a threat to mental health. It is necessary to manage the mental health of those affected by wildfires and the firefighters who responded.
A research team led by Kari Nadeau, a professor at Harvard University's T.H. Chan School of Public Health, announced on the 5th that exposure to fine particulate matter (PM2.5) from wildfires is linked to an increase in emergency room visits for mental health issues. The findings were published in the medical journal "JAMA Network Open."
So far, wildfire smoke has been known to produce various harmful substances, including fine particulate matter, benzene, and formaldehyde, which have harmful effects on respiratory and cardiovascular health. As a result, previous studies have focused on physical health issues, while the impact on mental health has been relatively overlooked.
The researchers analyzed the correlation between fine particulate matter from wildfires and mental illness. The study was based on medical data from California, where large wildfires occurred from July to December 2020. The team calculated the concentration of fine particulate matter caused by wildfires by region and investigated the number of emergency room visits related to mental health during the same period. The analysis included various mental disorders, such as depression and anxiety.
During this period, there were a total of 86,588 emergency room visits for mental health issues. The average daily concentration of fine particulate matter from wildfires was 6.95 µg (micrograms; 1 µg is one-millionth of a gram) per cubic meter of air, reaching a peak of 24.9 µg in September.
The analysis revealed a trend in which increased concentrations of wildfire-derived fine particulate matter correlated with a rise in emergency room visits for mental health disorders. The researchers explained that for every 10 µg (micrograms; 1 µg is one-millionth of a gram) increase in fine particulate matter concentration per cubic meter, there was an increase in emergency room visits for mental health issues lasting up to seven days. This means that cases of seeking medical care for mental health issues continued to occur for up to one week after short-term exposure to wildfire smoke.
Professor Nadeau noted, "Wildfire smoke is not just a respiratory issue; it also affects mental health," adding, "This study shows that smoke itself can play a direct role in worsening mental health issues such as depression, anxiety, and mood disorders."
A more serious problem is that the impact is concentrated in vulnerable groups. The researchers highlighted that children, low-income individuals, and people with disabilities are disproportionately affected.
Co-author Dr. Jeong Yoon-soo from Harvard University's T.H. Chan School of Public Health said, "This study shows that health disparities based on gender, age, and insurance status can be exacerbated by wildfire smoke," and emphasized the need to establish a system that allows everyone to access mental health services adequately as wildfires become more frequent and severe.
References
JAMA Network Open (2025), DOI : https://doi.org/10.1001/jamanetworkopen.2025.3326