Sulfur-dioxide (7446095) passive monitors were tested in the laboratory and under field conditions. Sampling rate and capacity, stability during exposure and storage, performance, accuracy, and precision were evaluated. The monitors tested were the DuPont air monitoring badges, the 3M sulfur-dioxide monitor, Mine Safety Appliances (MSA) Vapogard dosimeter tubes, Reiszner Environmental and Analytical Laboratories (REAL) badges and the REAL badges with water. A field sampler chamber was constructed. Monitors were exposed to sulfur-dioxide concentrations of 10 parts per million (ppm) for 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, 10.0, and 12.0 hours. All monitors except the 3M exhibited high uptake rates for exposure times of less than 30 minutes. All monitors had a precision within 10 percent, except the MSA. Field data was consistent with laboratory data. Only the REAL badges with water monitor were good for storage of both ambient and refrigerated samples. All monitors except the MSA were stable during exposure. The DuPont badges performed well for all factors tested. The MSA dosimeter tubes did not perform satisfactorily for most of the factors tested.