(Reuters Health) - Firefighters have higher than average cancer rates, and while their exposure to carcinogens during fires is well known, a new study suggests exposures in fire stations contribute to their excess cancer risk, too.

“Firefighters spend large portions of their shift waiting for calls in a station, during which they can be exposed to diesel exhaust from idling trucks (which is a known carcinogen) and off-gassing from contaminated post-fire gear (which may be contaminated with a variety of known and/or possible carcinogens),” researchers point out in the Journal of Occupational and Environmental Medicine.

Several studies in recent years have found that firefighters have elevated risks for cancers of the lungs, skin, esophagus, brain, kidney and prostate.

“We know about the chemicals, heat and stress in the field, but what’s left out is the chronic low-level exposure at the fire station during day-to-day business,” lead study author Dr. Emily Sparer of Harvard’s Dana-Farber Cancer Institute in Boston told Reuters Health by phone.

The Boston Fire Department approached Sparer’s team with concerns about firefighters becoming sick at young ages. Although department staff knew that diesel exhaust, dust and ash caused sinus and breathing issues, they weren’t sure when and where the most exposure occurred.

“There are still a lot of questions about why firefighters get cancer,” Sparer said. “By delving into the stations, we’re trying to start the process of answering those questions.”

Sparer and colleagues sampled air particles at four Boston fire stations in spring 2016, looking for particulate matter less than 2.5 millimeters in diameter. These small particles are considered dangerous to human health because they can be inhaled and become lodged in the lungs. They also looked for particle-bound polycyclic aromatic hydrocarbons, which are chemicals released from burning coal, oil, gas, trash and wood.

They took air samples from the kitchen, truck bay, and outside the station - and conducted interviews with officers at each station to understand health and safety-related policies and practices, such as engine idle-time and washing of contaminated clothing.

Particulate matter was present in higher concentrations in the truck bay than in either the kitchen or the outdoors, but levels varied throughout the day.

Newer building materials and effective separation between the different building zones helped keep levels low in the firefighters’ living areas, the study authors found. Policies for ventilating truck exhaust outside and the washing of bunker gear after a fire also had large influences on air quality.

“What stuck out to me was the degree to which the built environment matters in these stations,” Sparer said. “Seeing the numbers, hearing the stories, and being there in person really helped.”

Sparer and colleagues hope to sample air in additional stations and at different times of the year. They’re also talking to officers at the Boston stations about simple steps they can take to reduce risks, such as removing gym equipment from the truck bay, installing commercial-grade washing machines for gear, and closing doors to living areas, when possible.

“We’re not saying that every old fire department should tear down its station. That’s not feasible,” she said. “But design matters, and there are a few small changes that could prevent these exposures.”

A limitation of the study is the small size, which makes it difficult to assess whether the exposure numbers are exceptional, said Eero Pukkala of the University of Tampere in Helsinki, Finland. Pukkala, who wasn’t involved with this study, has studied cancer among firefighters in Finland, Norway, Denmark, Iceland and Sweden.

Comparison with other indoor locations, such as other workplaces, would be helpful as well to understand the numbers and the severity that firefighters face, he told Reuters Health by email.

“Of course, it’s important to understand whether these pollutants cause health hazards,” Pukkala added.

SOURCE: bit.ly/2vWEO6q Journal of Occupational and Environmental Medicine, online August 2, 2017.