“Cancer in the fire services is exploding exponentially,” Finn said. “Boston is at the epicenter.”

After more than 30 years on the force and three of them as commissioner, Finn, a Neponset native, is wrangling new equipment, new facilities, fine-tuning response times, and working with other first responders and fire departments to better address the longstanding risks and the expanding role of a modern urban fire force.

“The cancer rate is probably my biggest focus right now,” he said, sitting in the cafeteria of Florian Hall in Dorchester on Monday as a health fair took place. “Certainly, [there’s] public safety and the public. We’re doing a pretty good job on the civilian side of the house. Civilian fire deaths are down. We’re getting there, we’re doing our thing. Now I’m really focused on where we are with our firefighters.”