Residents living near where a wildland fire is burning or those in the vicinity of the smoke are told to stay indoors or leave the area altogether because of the contaminants the smoke is known to contain. But what about the firefighters on or near the front lines fighting the fires? They are breathing in the smoke, usually without the full oxygen equipment a structural firefighter uses. What kind of damage could that smoke be doing? That’s what So- Min Cheong, associate professor at the Bush School of Government, along with the Texas A&M Forest Service and researchers from Stanford University School of Medicine, collected data from 56 firefighters, each equipped with an Apple Watch and an air quality sensor. It has a sensor that measures the user's heart rate. The air quality sensor they carry measures the air surrounding the firefighter as they move around. Cheong said the lungs have been studied a lot in conjunction with wildfire smoke and health, but not the heart.