ON THE JOB: Firefighters battle the Loma Prieta fire in California in 2016.


Wildfire Researcher

Kathleen Navarro works alongside firefighters to learn how wildfires affect human health

When firefighters battle wildfires, they face intense heat and fast-moving flames. But the risks don’t end there. They can also inhale large amounts of smoke, which contains a mix of potentially dangerous chemicals and pollutants. Wildfire researcher Kathleen Navarro tracks firefighters’ smoke exposure to find ways to help keep them safe.

Navarro, who works for the U.S. Forest Service, heads into the field with firefighters throughout the West, armed with tools to measure the airborne toxins they encounter. She also studies how smoke affects residential communities near wildfires. She spoke with Science World about what she’s learned working in the midst of these massive infernos.

How did you first become interested in studying the health effects of wildfires?

In graduate school, I studied environmental health, or how chemicals in the environment affect human health. I was interested in fieldwork, or research outside the laboratory. Some scientists I knew had been examining air pollutants called polycyclic aromatic hydrocarbons. Some of these substances are known or suspected carcinogens that may increase the risk of cancer. Others are associated with heart and lung problems. These chemicals are produced when things burn, so I wondered how much wildland firefighters were exposed to them.

How did you go about joining firefighting teams in the field?


First I had to complete a week of training in fire school and pass a fitness test to qualify as a wildland firefighter. Then park managers in Sequoia and Sierra National Forests in California gave me permission to do my research with their crews. I attached monitoring equipment to the shoulder straps of firefighters’ backpacks. Some of the devices electronically analyzed the content of the air they were breathing. Others contained small filters that captured samples I could analyze later for the presence of chemicals.

While I collected data, my training allowed me to actually work as a firefighter with the crews. I’ve worked with firefighters in almost every western state and even measured smoke exposure for Hot Shot crews. These elite firefighting teams battle the most serious wildfires.

What did your fieldwork reveal?

Our data showed that firefighters are exposed to elevated levels of polycyclic aromatic hydrocarbons. Their exposure is within occupational safety limits—the regulations that say how much workers can be exposed to on the job—but higher than most people’s. I’m currently trying to determine how much these pollutants increase firefighters’ risk of health problems.

Did your research provide insight into ways to protect firefighters from smoke exposure?

Yes, my findings, combined with my firsthand observations of firefighters’ working conditions, helped me come up with ideas for reducing their exposures. For example, fighting an active fire is a really smoky situation. So crews can rotate in shifts to help limit their exposure. Firefighters also have to extinguish smoldering material that could reignite after the main fire has been put out. They can reduce ash and dust inhalation by moving only as far into the smoldering area as absolutely necessary.

What have you learned about how smoke pollution from wildfires might affect communities?

We looked at how a kind of pollution called particulate matter spread from the 2013 Rim Fire, the third-largest wildfire in California history. We found elevated levels of these tiny airborne particles not only in communities nearby but also hundreds of miles away in Nevada. The levels weren’t especially worrying. They were lower than average levels in many cities, but it was interesting to learn that these pollutants traveled so far.

What do you find most rewarding about your job?

Firefighters help so many people. I like that I get to help them. By talking with them about the chemicals in smoke, I get them thinking about protecting their long-term health. Working in the field is also a great mental and physical challenge. And it’s a chance to give back to the people affected by wildfires.

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