Wildfire smoke exposure may affect fertility, study finds
Oct 1, 2025, 2:21 PM | Updated: 2:23 pm
Wildfire smoke lingers in the air in Seattle. (Photo courtesy of KIRO 7)
(Photo courtesy of KIRO 7)
A new study from UW Medicine finds that wildfire smoke exposure may affect fertility.
Researchers analyzed samples from 84 men undergoing fertility treatments between 2018 and 2022. In 2018, 2020, and 2022, there were major smoke events in the Seattle area; the study found consistent declines in sperm count during those times.
“These results reinforce growing evidence that environmental exposures—specifically wildfire smoke—can affect reproductive health,” said senior author Dr. Tristan Nicholson, an assistant professor of urology in the University of Washington School of Medicine and a reproductive urologist at UW Medicine’s Men’s Health Center.
Nicholson’s patients were primarily men with fertility issues.
RELATED STORIES
Additional studies show wildfire smoke can affect fertility
Smaller studies led by Oregon Health and Science University showed similar results, linking air pollution and wildfire smoke to impaired reproductive health.
“As we see more frequent and intense wildfire events, understanding how smoke exposure impacts reproductive health is critical,” Nicholson said.
The study did not determine whether sperm count goes back up when the wildfire smoke clears.
“We are very interested in how and when sperm counts recover after wildfire smoke exposure,” Nicholson said. “Currently, we are conducting a prospective pilot study of men in the Seattle area to evaluate how wildfire smoke affects sperm quality.”
The research was published in Fertility and Sterility.
Frank Lenzi is the News Director for KIRO Newsradio. Read more of his stories here.
