Everyday firefighters put their lives on the line both physically and health-wise. “When something's on fire. You're not sure what's burning,” said Phoenix Fire Chief Kara Kalkbrenner. Despite all the protective fire gear and training, firefighters are not 100 percent protected from on-the-job dangers. “Your face is dirty. Your hands are dirty. You wipe your face. You breathe it in. Through inhalation, absorption. Those are some of the pathogens that can get into your system,” said Chief Kalkbrenner. Officials say cancer is the No. 1 killer of firefighters. They are 50 percent more likely to get diagnosed with cancer than the average person. 343 firefighters lost their lives on 9/11. Since then, nearly 7,000 first responders have been diagnosed with cancer due to exposure at the World Trade Center.