By Mihir Zaveri

As smoke from the Camp Fire drifted over the San Francisco Bay Area this week, clouding the air around Amika Mota’s home in Oakland, she was reminded of her time in prison.

While serving a sentence for vehicular manslaughter, Ms. Mota, 41, began putting out car, structure and wildfires in Central California in 2012, one of roughly 4,000 inmate firefighters in the state. Through firefighting, the state tries to rehabilitate prisoners while providing a critical — and cost-effective — line of defense against a growing threat of natural disaster.

Ms. Mota found it to be a “transformative” experience that was a welcome and productive reprieve from prison’s widespread drugs, violence and abuse. She said she would have “loved” to make firefighting her career.

Yet she remembers one lesson that was drilled into her head: After you are released, do not expect to be a firefighter anymore — criminals will not get hired. So when she was released on parole several years ago, she did not apply.

“It had been really ingrained in me by the folks that trained me that it was not possible,” Ms. Mota said.

She is one of many former inmates who volunteered to help defend the state from perennial fires for little pay, in some cases risking their lives, but who now find fire departments unwilling to hire them.

As the Camp Fire rages in Northern California, the deadliest and most destructive in state history, and wildfires scorch western Los Angeles, about 1,500 inmates have been deployed to help fight active fires, out of a firefighter total of roughly 9,400, according to California state officials.

Ms. Mota does believe she learned invaluable skills in the program that she has translated into a career helping other former prisoners at the Young Women’s Freedom Center, a nonprofit group in San Francisco.

But since she was released from prison, Ms. Mota said, she also thinks about how, year after year, the wildfires seem to grow stronger. She thinks about how, on average, inmate firefighters are paid $2 per day, and another $1 per hour when fighting active fires. She thinks about how six inmate firefighters have died since 1983, according to the state, and how, ultimately, she hears about so many who, like her, are discouraged from applying or are barred from being firefighters because of their criminal records.

“I also begin to really look at the injustice of what it looks like to be this massive labor force for the state of California that’s getting paid pennies on the dollar,” she said. “We should be doing a lot more to make sure that folks are re-entering in a positive way.”

California relies on prisoners to fight wildfires more than any other state. In 1946, the state opened Camp Rainbow in Fallbrook, which housed inmates to fight fires. Over the decades, the program would grow.

Today, 3,700 inmates work at 44 fire camps across the state, said Alexandra Powell, a spokeswoman for the California Department of Corrections and Rehabilitation, which helps run the fire camp program.

Men, women and youths can volunteer for the program, under certain restrictions. For example, they must have five years or less remaining on their sentences. Those convicted of rape or arson are disqualified, Ms. Powell said. Those who volunteer can receive time off their sentence, she added.

“Through rehabilitation, and programs like the fire camp program, inmates learn useful skills that can help them on the outside,” Ms. Powell said. “These firefighters are working hard to help the people of California in their time of need. They are repaying their debt to society in a productive way.”

Ms. Mota, despite her concerns, said she was a champion of the program and wanted it to be available for others.

The program has increasingly drawn scrutiny from criminal justice reform advocates, who have called it one of the most striking examples of undercompensated prison labor.

It also illustrates how convictions can have lasting impacts on people’s lives, said Angela Hanks, the director of the Center for Postsecondary and Economic Success at the Center for Law and Social Policy, a Washington-based nonprofit group that promotes policies that help low-income Americans.

Ms. Hanks said that incentives given to prisoners to join the fire camps, such as reduced sentences, might draw some who would otherwise not want to join the program.

“It is such a dangerous job,” she said. “At a minimum, people should be paid a fair wage.”

Once they are released from prison, inmates find it difficult to join the ranks of professional firefighters, said Katherine Katcher, the founder and executive director of Root and Rebound, a nonprofit group that helps people with criminal histories re-enter society. Some former inmates, like Ms. Mota, don’t bother applying, Ms. Katcher said. Some fire departments also bar people with certain criminal backgrounds from becoming firefighters, she said.

For example, the fire department in Bakersfield, a city of more than 380,000 people in Southern California, said it disqualified applicants who have been convicted of a felony. In the Los Angeles County Fire Department, felonies and some misdemeanors are grounds for disqualification, said Capt. Tony Imbrenda, a department spokesman.

“I can tell you that someone who has been incarcerated and part of an inmate hand crew has no chance of employment with this agency,” he said.

Various counties also have restrictions on who can get a license to be an emergency medical technician, which is required by many fire departments in California, Ms. Katcher said. State law directs local E.M.S. agencies to deny an E.M.T. certification if the person has been convicted of two or more felonies, or has been convicted of any theft-related misdemeanor in the preceding five years, among other possible factors.

This year, California legislators debated a bill that would have directed local agencies to, in some cases, not let criminal history be a reason to deny certification. Instead, legislators scaled it down, deciding instead to pass a bill that would collect data on people’s being denied.

California is looking for other ways to help inmate firefighters get jobs. Ms. Powell said the state was opening a training and certification program in Ventura County that is intended “to create a pathway for former offenders to compete for entry-level firefighting jobs with the state.”

For Ms. Katcher, the initiatives are not enough.

“Our state has the opportunity to improve its laws to do better,” she said. “It’s not just about saying a program is rehabilitative. That’s just a word. Do the right thing.”