Jon Paul was leery entering his first wildfire camp of the year late last month to fight three lightning-caused fires scorching parts of a Northern California forest that hadn’t burned in 40 years.

The 54-year-old engine captain from southern Oregon knew from experience that these crowded, grimy camps can be breeding grounds for norovirus and a respiratory illness that firefighters call the “camp crud” in a normal year. He wondered what the coronavirus would do in the tent cities where hundreds of men and women eat, sleep, wash and spend their downtime between shifts.

Paul thought about his immunocompromised wife and his 84-year-old mother back home. Then he joined the approximately 1,300 people spread across the Modoc National Forest who would provide a major test for the COVID-prevention measures that had been developed for wildland firefighters.

“We’re still first responders and we have that responsibility to go and deal with these emergencies,” he said in a recent interview. “I don’t scare easy, but I’m very wary and concerned about my surroundings. I’m still going to work and do my job.”

Paul is one of thousands of firefighters from across the U.S. battling dozens of wildfires burning throughout the West. It’s an inherently dangerous job that now carries the additional risk of COVID-19 transmission. Any outbreak that ripples through a camp could easily sideline crews and spread the virus across multiple fires — and back to communities across the country — as personnel transfer in and out of “hot zones” and return home.

Though most firefighters are young and fit, some will inevitably fall ill in these remote makeshift communities of shared showers and portable toilets, where medical care can be limited. The pollutants in the smoke they breathe daily also make them more susceptible to COVID-19 and can worsen the effects of the disease, according to the Centers for Disease Control and Prevention.

Also, one suspected or positive case in a camp will mean many other firefighters will need to be quarantined, unable to work. The worst-case scenario is that multiple outbreaks could hamstring the nation’s ability to respond as wildfire season peaks in August, the hottest and driest month of the year in the western U.S.

The number of acres burned so far this year is below the 10-year average, but the fire outlook for August is above average in nine states, according to the National Interagency Fire Center. Twenty-two large fires ignited on Monday alone after lightning storms passed through the Northwest.

A study published this month by researchers at Colorado State University and the U.S. Forest Service’s Rocky Mountain Research Station concluded that COVID outbreaks “could be a serious threat to the firefighting mission” and urged vigilant social distancing and screening measures in the camps.

“If simultaneous fires incurred outbreaks, the entire wildland response system could be stressed substantially, with a large portion of the workforce quarantined,” the study’s authors wrote.

This spring, the National Wildfire Coordinating Group’s Fire Management Board wrote — and has since been updating — protocols to prevent the spread of COVID-19 in fire camps, based on CDC guidelines. Though they can be adapted by managers at different fires and even by individual team, they center on some key recommendations:

Firefighters should be screened for fever and other COVID symptoms when they arrive at camp.

Every crew should insulate itself as a “module of one” for the fire season and limit interactions with other crews.

Firefighters should maintain social distancing and wear face coverings when social distancing isn’t possible. Smaller satellite camps, known as spike camps, can be built to ensure enough space.

Shared areas should be regularly cleaned and disinfected, and sharing tools and radios should be minimized.

The guidelines do not include routine testing of newly arrived firefighters — a practice used for athletes at training camps and students returning to college campuses.

The Fire Management Board’s Wildland Fire Medical and Public Health Advisory Team wrote in a July 2 memo that it “does not recommend utilizing universal COVID-19 laboratory testing as a standalone risk mitigation or screening measure among wildland firefighters.” Rather, the group recommends testing an individual and directly exposed co-workers, saying that approach is in line with CDC guidance.

The lack of testing capacity and long turnaround times are factors, according to Forest Service spokesperson Dan Hottle.

The exception is Alaska, where firefighters are tested upon arrival at the airport and are quarantined in a hotel while awaiting results, which come within 24 hours, Hottle said.

Fire crews responding to early-season fires in the spring had some problems adjusting to the new protocols, according to assessments written by fire leaders and compiled by the Wildland Fire Lessons Learned Center.

Shawn Faiella, superintendent of the interagency “hotshot crew” — so named because they work the most challenging or “hottest” parts of wildfires — based at Montana’s Lolo National Forest, questioned the need to wear masks inside vehicles and the safety of bringing extra vehicles to space out firefighters traveling to a blaze. Parking extra vehicles at the scene of a fire is difficult in tight dirt roads — and would be dangerous if evacuations are necessary, he wrote.

“It’s damn tough to take these practices to the fire line,” Faiella wrote after his team responded to a 40-acre Montana fire in April.

One recommendation that fire managers say has been particularly effective is the “module of one” concept requiring crews to eat and sleep together in isolation for the entire fire season.

“Whoever came up with it, it is working,” said Mike Goicoechea, the Montana-based incident commander for the Forest Service’s Northern Region Type 1 team, which manages the nation’s largest and most complex wildfires and natural disasters. “Somebody may test positive, and you end up having to take that module out of service for 14 days. But the nice part is you’re not taking out a whole camp. … It’s just that module.”

The total number of positive COVID cases among wildland firefighters among the various federal, state, local and tribal agencies is not being tracked. Each fire agency has its own system for tracking and reporting COVID-19, said Jessica Gardetto, a spokesperson for the Bureau of Land Management and the National Interagency Fire Center in Idaho.

The largest wildland firefighting agency is the Agriculture Department’s Forest Service, with 10,000 firefighters. Another major agency is the Department of the Interior, which BLM is part of and which had more than 3,500 full-time fire employees last year. As of the first week of August, 111 Forest Service firefighters and 40 BLM firefighters (who work underneath the broader Interior Department agency) had tested positive for COVID-19, according to officials for the respective agencies.

“Considering we’ve now been experiencing fire activity for several months, this number is surprisingly low if you think about the thousands of fire personnel who’ve been suppressing wildfires this summer,” Gardetto said.

Goicoechea and his Montana team traveled north of Tucson, Arizona, on June 22 to manage a rapidly spreading fire in the Santa Catalina Mountains that required 1,200 responders at its peak. Within two days of the team’s arrival, his managers were overwhelmed by calls from firefighters worried or with questions about preventing the spread of COVID-19 or carrying the virus home to their families.

In an unusual move, Goicoechea called upon Montana physician — and former National Park Service ranger with wildfire experience — Dr. Harry Sibold to join the team. Physicians are rarely, if ever, part of a wildfire camp’s medical team, Goicoechea said.

Sibold gave regular coronavirus updates during morning briefings, consulted with local health officials, soothed firefighters worried about bringing the virus home to their families and advised fire managers on how to handle scenarios that might come up.

But Sibold said he wasn’t optimistic at the beginning about keeping the coronavirus in check in a large camp in Pima County, which has the second-highest number of confirmed cases in Arizona, at the time a national COVID-19 hot spot. “I quite firmly expected that we might have two or three outbreaks,” he said.

There were no positive cases during the team’s two-week deployment, just three or four cases where a firefighter showed symptoms but tested negative for the virus. After the Montana team returned home, nine firefighters at the Arizona fire from other units tested positive, Goicoechea said. Contact tracers notified the Montana team, some of whom were tested. All tests returned negative.

“I can’t say enough about having that doctor to help,” Goicoechea said, suggesting other teams might consider doing the same. “We’re not the experts in a pandemic. We’re the experts with fire.”

That early success will be tested as the number of fires increases across the West, along with the number of firefighters responding to them. There were more than 15,000 firefighters and support personnel assigned to fires across the nation as of mid-August, and the success of those COVID-19 prevention protocols depend largely upon them.

Paul, the Oregon firefighter, said that the guidelines were followed closely in camp, but less so out on the fire line. It also appeared to him that younger firefighters were less likely to follow the masking and social-distancing rules than the veterans like him. That worried him as he realized it wouldn’t take much to spark an outbreak that could sideline crews and cripple the ability to respond to a fire.

“We’re outside, so it definitely helps with mitigation and makes it simpler to social-distance,” Paul said. “But I think if there’s a mistake made, it could happen.”