Large-scale field studies were conducted initially in Boise, Idaho, and then in Roanoke, Virginia, during the 1986-87 and 1988-89 winter heating seasons, respectively, to evaluate the impact of residential wood combustion (RWC), residential distillate oil combustion (RDOC), and automotive emissions on the ambient and indoor air quality. Consecutive 12-h samples were collected over a 4-month period at three primary and four auxiliary fixed sampling sites in each city. Each ambient site consisted of one or more particulate, organic, and gaseous samplers as well as selected criteria pollutant and meteorological monitors. Twelve-hour particulate, organic, and gaseous samples were concurrently collected inside 10 pairs of residences in each city over a 4-day period (2 weekdays and 2 weekend days). Each pair of Boise residences consisted of one home with and one home without an operating RWC appliance. The pair of Roanoke residences consisted of one home with and one home without an operating RDOC appliance. Similar sample sets were collected immediately outside the residence without the RWC/RDOC appliance. The samples have been analyzed and the key results summarized herein along with an overview of the monitoring program.