This story was originally published by High Country News and is reproduced here as part of the Climate Desk collaboration.

Fertility isn’t a topic that tends to come up in the macho, male-dominated world of wildland firefighting—at least not according to Jasper Kehoe, 23, who served as a Colorado wildland firefighter for four summers.

But whenever Kehoe talked about his job in the off-season—working as a student researcher at Colorado State University to assess the impact of wildfire smoke on semen—his colleagues’ ears perked up.

Even more surprising to Kehoe, they wanted to get involved: When he posted about the study in an industry Facebook group, he received more than 150 messages from firefighters who wanted to participate.

“After you get over the stigma of talking about fertility, somewhat of a taboo subject in our community,” Kehoe said, “these firefighters are concerned with the ability to conceive.”

Kehoe helped recruit 144 wildland firefighters to submit pre-, mid- and post-fire season semen samples over the past year. He hopes that his work helps lead to a greater understanding of smoke’s health consequences, as well as more protections for wildland firefighters and others.

“It’s not yet understood whether these impacts on sperm may translate to a change in pregnancy.”

When it’s published later this year or the next, the firefighter study will join a new body of research on how wildfire smoke influences human fertility. In comparison to smoke’s effects on pregnancies, it’s a topic that’s been understudied. But with climate change causing more fires, especially in the West, and infertility affecting 1 in 6 people worldwide, interest in the field is growing. And so far, the results hold some warning signs for Westerners who want to have........

© Mother Jones