Ann Arbor Times

A recent study from the University of Michigan suggests that high pollen counts may play a significant role in increasing suicide risk. The research, published in the Journal of Health Economics, found that during periods of elevated pollen levels, deaths by suicide rose by as much as 7.4%. The study points to the physiological effects of allergies—such as poor sleep and mental distress—as possible contributors to this increase.

Joelle Abramowitz, associate research scientist at the University of Michigan’s Institute for Social Research, explained, “A small shock could have a big effect if you’re already in a vulnerable state. We looked specifically at pollen from all different kinds of plants, including trees, weeds and grasses.”

Researchers categorized pollen exposure into four levels and observed a stepwise increase in suicide risk: 4.5% higher at the second level, 5.5% at the third, and peaking at 7.4% in the highest category.

The study analyzed daily pollen data from 186 counties across 34 metropolitan areas in the United States and matched it with suicide data from the National Violent Death Reporting System between 2006 and 2018. According to Abramowitz, “During our study period, there were nearly 500,000 suicides in the U.S. Based on our incremental data, we estimate that pollen may have been a contributing factor in up to 12,000 of those deaths over the period, or roughly 900 to 1,200 deaths per year.”

Abramowitz conducted the research with Shooshan Danagoulian and Owen Fleming of Wayne State University. They noted that while long-term factors for suicide are well studied, short-term triggers like allergy-related health shocks have received less attention.

The findings showed that individuals with existing mental health conditions or prior treatment had an even higher risk: an 8.6% increase in suicides on days with peak pollen counts. The researchers also found that white men accounted for much of this effect but noted unexpectedly high vulnerability among Black individuals.

Abramowitz stated that although their data is based on U.S. populations, similar patterns have been seen internationally: “While our study’s data comes from the U.S., our findings likely apply globally. This is supported by earlier research that found similar relationships in locations like Tokyo and Denmark. Our results, therefore, provide crucial new evidence that this phenomenon is a consistent, worldwide trend.”

Given these findings and considering climate change is expected to extend and intensify pollen seasons through this century—which could more than double related impacts—the authors recommend public health measures focused on education rather than reducing pollen-producing plants.

Suggestions include improved forecasting of high-pollen days and better communication so people can take preventive actions such as limiting outdoor activities or using antihistamines when necessary.

The authors also call for broader awareness among healthcare providers about environmental factors affecting mental health: “We should be more conscious of our responsiveness to small environmental changes, such as pollen, and our mental health in general,” Abramowitz said. “Given our findings, I believe medical providers should be aware of a patient’s allergy history, as other research has also established a connection between allergies and a higher risk for suicide. I hope this research can lead to more tailored care and, ultimately, save lives.”