Do emissions from natural gas stoves in American homes degrade respiratory health? The combustion of natural gas yields byproducts such as NOx , PM2.5 , and CO that the US EPA regulates outdoors. But while ambient air quality has improved in the US over the last few decades as a consequence of the Clean Air Act of and its amendments, the prevalence of asthma and morbidity and mortality associated with asthma continue to rise (Mannino /et al./, 1998). Concentrations of most air pollutants are higher indoors than outdoors in the US, however, and people in the US spend more than 90% of their time indoors on average‚Äî68.7% in their homes in particular (Weisel, 2002; Klepeis /et al/., 2001). Unvented combustion appliances, like natural gas stoves, are often primary sources of air pollution inside homes (Girman /et al./, 1982; Wallace 2006). Prior studies disagree over whether natural gas stoves degrade respiratory health, but most of these studies omit key determinants of indoor pollutant concentration and individual exposure. Based on an explicit model of pollutant concentration and personal exposure, I re-evaluate the effect of gas stoves on respiratory health using data from NHANES III and air exchange data from Murray and Burmaster (1996) . Preliminary findings show natural gas stove emissions have significant, negative effects on respiratory health--particularly for women. These effects, however, are diminished in larger and draftier homes, as theory suggests.