SANTA ROSA, Calif. — As fires spread across Northern California last year, Capt. Matt Alba and Strike Team 2253A found themselves wading through a smoldering jungle of plastic and metal in search of bodies.
As they worked through charred auto shops and trailers, Mr. Alba kept thinking about the poisons they were kicking up, and that they did not have a single mask or hazmat suit among them.
Wildfire fighting had changed.
For generations, firefighters fought mostly in desolate forests, where most of the dangers were fatigue and falling trees. But a confluence of modern factors — namely America’s rapid suburban expansion into the wilderness, combined with the growing ferocity of wildfires — is posing a host of new health threats to the men and women who fight these blazes.
While burning wood poses some threat to lungs, man-made products and the gases and particles they produce when burned are far more dangerous.
In the last three years, California has seen a record number of devastating fires, and thousands of firefighters have been exposed to chemicals they had not previously encountered in such high volumes.
Unlike urban firefighters dealing with structural blazes, these wildfire responders do not wear heavy gear that filters air or provides clean air because the gear is unwieldy and too limited to allow the kind of multi-hour, high-exertion efforts demanded on the front lines of these large outdoor infernos.
But some think more needs to be done to keep wildland firefighters safe.
Mr. Alba, who has been with the San Francisco Fire Department for 18 years, spent 11 days working in Paradise, Calif., last year, in a smog so thick it burned his lungs. As he picked his way through the wreckage, he said, his crew began to fall sick: severe headaches, brutal coughs.
“I was just thinking about 9/11,” he said of the many firefighters who fell ill after the 2001 terrorist attacks. “I asked myself: Is history repeating itself here?”
On Thursday, California’s fight against fire continued. More than 7,000 firefighters were battling blazes up and down the state, including new wildfires in the heavily populated areas of Riverside and San Bernardino Counties, fueled by rushing winds that for days have pushed flames through brush and dry fields and up the sides of homes.
The fires began just as winds eased in the north and firefighters wrangling the state’s largest active blaze, the Kincade fire, managed to contain more than half of its 76,800-acre footprint for the first time.
About 5,800 people remained under a mandatory evacuation order, a small fraction of the 180,000 who had been ordered to leave their homes on Sunday. Residents and firefighters were beginning to survey the damage on Thursday as many in Northern California and parts of Southern California began to return home.
Several studies have examined the health of firefighters who battle structural blazes in urban areas. The largest, a look at 30,000 people by the National Institute for Occupational Safety and Health, acknowledged that urban firefighters may be exposed to carcinogens like formaldehyde, benzene and asbestos, and found that firefighters have higher rates of several types of cancers than the population as a whole.
This has led some health advocates to declare an “epidemic” of cancer among urban firefighters, and to call for better equipment and health care.
Less is known about the health of wildland firefighters. Though that is changing.
Following the 2017 Tubbs fire that whipped through the Santa Rosa area, researchers at the University of California, Berkeley, working with the San Francisco Firefighters Cancer Prevention Foundation, analyzed blood and urine samples of about 150 firefighters. They found that in their blood many had elevated levels of mercury, as well as perfluoroalkyl substances, human-made chemicals known as PFAS, which have been linked to cancer.
Researchers said that the chemicals may have come off the buildings, or even the firefighters’ gear. PFAS, an increasingly controversial class of chemicals that are used as fire retardants, are often present in firefighter uniforms.
The exposure is compounded by dangers that firefighters have faced for years.
In Northern California this month, more than 5,000 firefighters and support staff gathered to fight the Kincade fire, turning the Sonoma County fairgrounds into base camp, a sea of white tents and dirt-smudged firefighters taking breaks from their 24-hour shifts.
The morning briefing included tips on avoiding exhaustion and falling trees — and a warning to watch out for the region’s abandoned mercury mines. (For decades starting around the 1870s, mercury was pulled from the ground and used to separate gold from other rocks. Many of those mines were never fully cleaned up.)
A flier handed out to firefighters said the mines posed “no health or inhalation hazards” if they were exposed to fire, as they had been capped with soil. But officials at the federal Bureau of Land Management said that was incorrect — that at least three of the mines had exposed waste that could be dangerous if hit by heat. (Cal Fire, the state firefighting agency, later issued a corrected version of the flier.)
More modern threats come from the growth of the country’s wildland-urban interface, a term increasingly used to describe the area where homes and forests meet.
As cities have become more expensive, these areas have become increasingly attractive places to settle, and more than 12 million homes were built in this liminal space between 1990 and 2010. With more people in the woods, there are more structures to defend.
More than 80 people died in the Camp fire near Paradise last year; most lived in areas that were basically wilderness. Firefighters now have to contend with protecting people who live in areas that some consider uninhabitable and the fallout of homes burning in these isolated locations.
At base camp in Sonoma, many said they were aware of these expanding chemical dangers. Cal Fire has a research and development team that is working to develop better gear for firefighters, said Eric Castellanos, a captain with the department.
But there is division among firefighters about exactly what should be done to protect them. Mr. Alba, the firefighter who was in Paradise, is calling on fire agencies to remove PFAS from their uniforms, and for officials to come up with a solution that protects them from noxious threats.
But Scott Ross, a firefighter from Shasta County, said he worried that more restrictions — heavier gear, for example — would make it harder for them to do their work.
“This is not a safe job,” he said. “You can’t make it safe. And the more you try, the more you tie our hands.”