Physical activity offers multiple benefits in preventing illnesses, such as cardiovascular disease and diabetes, and in improving well-being. This thesis examined air pollution exposure in Latina women participating in a faith-based program promoting physical activity classes, including outdoor walking activities around the neighborhood near their church. Although physical activity provides health benefits, exposure to near-traffic air pollution can negatively impact the participant's well-being, sometimes resulting in diseases that affect cardiovascular and respiratory systems. The aim of the present study was to examine personal exposures to traffic pollutants during the intervention. Air pollutants that were measured minute by minute next to participants in this study are those traffic pollutants that have been implicated in several diseases; black carbon (BC) or soot, a marker for diesel exhaust, carbon monoxide (CO), and ultrafine particles (UFP). BC concentration was measured with a microaethalometer, CO concentration with a Q Trak and UFP level was sampled using a P Trak condensation particle counter. A total of 24 outdoor and 9 indoor locations were assessed during the physical activity classes for a period of approximately 1 hour each time. The results indicate elevated concentrations of traffic pollutants BC and UFP at outdoor intervention sites closer to major roadways (median BC 1.1 - 1.4 µg/m3, median UFP 5,500 - 7,600 particles/cc) as compared to more rural areas (BC 0.4 - 0.8 µg/m3, UFP 2,100 - 3,700 particles/cc), although this difference was not significant (p = .05). Indoor locations showed no clear pattern, though sample size was small. This thesis is the first study to measure the toxic traffic pollutants black carbon and ultrafine particles minute by minute during a physical activity intervention, and was performed in a Latina population in mainly low-income neighborhoods. Further research may help low-income Latino neighborhoods define the cleanest locations for physical activity.