Ask Boston Fire Commissioner Joseph Finn what really keeps him up at night.

Civilian fire deaths? There hasn’t been a single one all year. More large-scale fires? They keep a wary eye, but the department is staffed to handle them as they come. Wood-framed housing everywhere? As long as fire suppression measures are in place, and fire prevention teams monitor their status, those buildings are generally safe.

For the more than 1,500 men and women of the Boston Fire Department, there is a slower, more insidious threat to their well-being than the immediate danger of a burning building, one that has claimed hundreds of their colleagues over the years.

“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.”

A ‘hotter and faster’ burn

Over the last 27 years, Finn said, some 200 Boston firefighters have died from occupational cancer, defined as a cancer caused wholly or in part by exposure to a carcinogen at work. Today, he added, there are about 16 members of the department off the work rolls with occupational cancer, six of them at stage four. All six were at a nine-alarm power plant fire in South Boston in 2002, after which 50 responders developed either an occupational cancer, a cardiac issue, or lung disease. Sixteen of those responders have died.

Finn said one 40-year-old firefighter and father of four, whose discovery of cancer after a blaze in Savin Hill was documented in a Boston Magazine article in March, is still "in the fight of his life" after rounds of chemotherapy and radiation.

“Fires burn much hotter and faster today than they did 30 years ago,” Finn said, citing a report from Underwriters Laboratories that compared burn times between a room full of legacy materials like wood and cotton against newer homes built and furnished with more synthetic materials.

There is an immediate physical risk, the study pointed out: A person had about 17 minutes to escape a fire 30 years ago, while the survival window today is only three or four minutes – and the burning materials themselves carry deadly particulates.

Plastics and chemical flame retardants, the latter long permitted in the city despite their tendency to become carcinogenic particles when exposed to high enough temperatures to burn, pose serious risks if inhaled or allowed to sit on the skin. While the city council recently modified the fire prevention codes to align with state standards, lingering flame retardants exist in all manner of furniture.

New recruits have to know the hazards going in, Finn said. It is, of course, an inherently dangerous job, and following protocols like keeping masks on and limiting damaging exposure can save the health and lives of scores of young responders.

“My biggest issue, which I think [through] everything we’ve done as a department, we’re changing the culture around this cancer issue,” Finn said. “We’re focusing our training. We’re focusing on all the equipment we purchase, we’re focused on longer-duration breathing apparatus, we’re focusing on quick decon after the fire. That’s around trying to reduce those cancer numbers.”

Funding a safer path

The changing attitude toward long-term medical risks associated with firefighting is being borne out in city investments, Finn said. He credits Mayor Martin Walsh with being a stalwart ally of the department, championing expenditures like $4.5 million in new oxygen tanks to give first responders 50 percent more air.

Two new fire stations, the first in about 30 years, stand to benefit from a new way of looking at fire facilities, Finn said.

Engine 42 in Roxbury and Engine 17 on Meetinghouse Hill in Dorchester are slated for massive overhauls. The Meetinghouse Hill station was budgeted for $19 million across five years in the most recent city capital budget.

Fire officials say the station is sorely needed to support one of the busiest fire companies in the city. Fire Department officials are in talks with First Parish Church about the possibility of constructing the new station on vacant church-owned property closer to the Winter Street intersection.

Mayor Walsh wants to put forward a replacement of a new fire house in every capital plan going forward, Finn said.

A modern Boston firehouse is basically constructed with hazmat principles, Finn said. The main floor, with the apparatus bay and bunker gear storage area, is the “hot zone,” with its own separate mechanical systems and air handling. The “warm zone” includes hermetically sealed stairways and everything between floors. Living quarters and kitchen areas are the “cold zone.”

“So there’s no cross contamination between diesel exhaust, or gear you’re bringing back that’s been at a fire, gassing up the firehouse and contaminating the air inside the firehouse,” he said.

The challenges for Boston

“The way we approach the fire problem in the city of Boston, and when you look at us compared to other communities across the country, you’ve got to think about how dense we are,” Finn said. “You look at some of our neighborhoods, all wooden structures, you look at the attached dwellings. We have some significantly problematic neighborhoods from a fire perspective.”

Beacon Hill and the North End, with their narrow streets and tightly packed buildings, experience fires that “are almost always serious and it’s almost always a tragedy,” the commissioner said.

There have been a number of high-profile fires this year for the department to deal with. Finn pointed to a summer fire at the Treadmark building in Ashmont, now demolished down to its concrete base after a six-alarm blaze and sustained hours of firefighting left floors of wood framed construction beyond repair.

“The Treadmark was first, then Waltham, then Weymouth, and there’s gonna be more,” he said. “Those buildings are inherently dangerous when they’re under construction. It’s simply that you have a vertical lumber yard. And the practices on the construction sites make them more vulnerable.”

With the Treadmark, there was an almost entirely complete building with a prepped sprinkler system that was not yet turned on. Workers who saw the initial smoke were delayed in calling the fire department. These factors “turned what probably could have been a $40,000 loss into a $40 million loss,” Finn said.

Better systems need to be in place to protect the neighborhoods around such structures, he said, and it may come down to insurance considerations rather than code changes.

The city’s increasing density is a concern, Finn said. His fire prevention division keeps a watchful eye on where new building is occurring, and the construction unit just added two members.

“I have problems with those buildings under construction when they’re in high density neighborhoods,” he said. “They’re going up everywhere. When you have them going up into a high density neighborhood already, and they catch fire, they’re going to spread down the block, and the chase is on, and let the wind be a little factor in this and it’s a blowtorch effect.”

Steady expansion

As the heavy hitter in the Boston metropolitan area, his department has “a whole multitude of things we go to daily,” Finn said, from small fires, to medical responses, to rescues, to major incidents. “Not every day’s the same. It’s not like it’s a boring job.”

The department, which has 35 stations in 9 districts, is “adequately staffed,” Finn said. Any department could use more members, he noted, and they are examining district layouts to see if there are ways to speed up leadership response times to certain fire districts.

Fire department calls are “predominantly EMS calls right now,” he said, and each fire apparatus carries narcan to address overdoses. Responders administered about 700 doses of narcan last year, he said, and their fleet of EMTs keeps response times to around four minutes.

Responders are aided in their speed and effectiveness by new technology and new equipment.

Nine new ladder trucks were added out of 20 — “that’s unheard of” — and 23 new engines are joining the fleet. They aren’t adding to the fleet’s overall numbers, rather, they are replacing worn-down trucks and simplifying operations. With a new jacking system, a job that used to be a multi-person job can be handled by one firefighter long enough to keep an incident at “its incipient stage” until backup can arrive, Finn said.

Biodegradable suppressant foam, which they have been using recently to great effect, can quash a fire in its tracks long before standard water hoses could, the commissioner noted, adding, again, “it’s all about reducing the exposure time.”

Finn says none of the advances would be possible without the support of Richard Paris with Local 718, "a very solid relationship," especially around cancer and the opioid responses. His command staff has also been "fabulous," Finn said. "Everyone understands what we're trying to do."

Around the metropolitan region, the department coordinates with eight other communities as part of the Urban Area Security Initiative to deal with anything terrorism or homeland security related.

“Things are changing in the fire service,” Finn said. “Look at the shooting [in Las Vegas]. There’s active shooter stuff, the terrorism. These are things we weren’t worried about 20 years ago. This wasn’t on our radar. The fact is that the fire department is not just ‘the fire department,’ it’s a multi-purpose response agency.”

Jennifer Smith can be reached at jennifer.smith@dotnews.com, or follow her on Twitter at @JennDotSmith