NORTH COUNTY -- Fresh off the fire line, where the air was choked with ash and acrid smoke, Tularo County firefighter Toni VanGaasbeek, 22, relaxed on the grass at Kit Carson Park in Escondido on Thursday and stifled intermittent coughs.

Scattered around the staging area, dozens of other firefighters blinked bloodshot eyes and stretched their stiff limbs.

For the men and women battling the blazes that have ravaged the region this week, aches and pains-- from irritated throats to sprains to burns -- are an accepted occupational hazard.

Many have worked grueling shifts -- in some cases, more than 48 hours -- in one of the world's most aggressive environments.

"The first few days were the worse," said CalFire firefighter Robert Jimenez, 33, who began battling the Witch Creek fire when it began in Ramona on Sunday. "We were basically in an ember storm, sucking that stuff in."

By Thursday afternoon, the California Department of Forestry and Fire Protection put the injured firefighter tally at 42 from the Witch Creek, Harris, Poomacha and Rice fires, which have devastated San Diego County over the past five days .

The most severe came injuries Sunday afternoon, when four firefighters on the Harris fire "had some significant burn issues," said CalFire spokesman Matt Streck.

Injuries are only reported to the media if they're serious enough to take a firefighter away from the action, Streck said. Smaller aches, pains and irritations are just part of the job, and firefighters learn to suck it up.

"Since day one of these fires, I've had something in my left eye, and I haven't had a chance to get it out," said Streck, his voice tinged with fatigue.

At a medical tent at Kit Carson park, Tim Day -- a physicians' assistant treating inmate firefighters for the California Department of Corrections -- said he's primarily dealt with skin and eye problems.

"When you think of all the things that could happen, we've been very fortunate," Day said Thursday.

But that could change in the next few days, he said. With the wind dying down and hand crews digging deeper into the brush, Day predicted, "we're going to see a mushrooming of severe poison oak," which can irritate the skin, and, when burned, inflame the lungs.

At that's not all. Life on the fire line inevitably means spending long hours in harsh smoke, often with just a bandana over your face (other masks can be too restrictive for the sweltering environment), firefighters said.

"There's a lot of debate out there about what the long-term effects are," Streck said. "The concern is not really the particulates, but it's the chemicals in the air."

Wildfire smoke contains hundreds of compounds, including carbon monoxide, suspended particulates, and dangerous gasses called aldehydes, according to the U.S. Forest Service.

As a precautionary measure, CalFire tests its employees' respiratory capacity on a semi-annual basis, Streck said.

Dr. Martin Nielsen, a pulmonary and critical care critical care specialist at Tri-City Medical Center, said the likelihood of developing permanent lung problems from exposure to wildfire smoke over a relatively short duration -- compared to, say, a lifetime smoking habit -- was low.

But the story may be different for long-term firefighters, he said.

"Down the line, if a person has had enough exposure, conceivably they could have chronic bronchitis or chronic asthmatic bronchitis from that exposure," Nielsen said.

Asked about the health hazards of battling the San Diego blazes, Mike Reeder, a CalFire firefighter for 23 years, said it was just the "nature of our job."

Relaxing in the shade at Kit Carson, Reeder lit a cigarette and joked about injuries he'd suffered over the years: burns on his nose and feet, a lorn knee ligament, broken ribs.

"We call him granddaddy," Jimenez quipped.

Reeder said wildland firefighters know what they're getting into when they accept the job.

"You save one life, it makes your whole career," he said.

Contact staff writer Craig TenBroeck at (760) 901-4062 or ctenbroeck@nctimes.com.