We are used to being concerned about air pollution outdoors, but we aren't used to thinking about air pollution when we're inside our homes," Rob Jackson, the study's senior author and an earth system science professor at the Stanford Doerr School of Sustainability, told SFGATE. "For the average American, one quarter of all the asthma-triggering nitrogen dioxide that they breathe comes from their stove indoors. That's not something most people are aware of.