Airborne measurements of gases and aerosols from the recently activated volcanic vents on Mt. Baker were made in March 27 and June 30, 1975. The total rates of emission of gaseous sulfur on these two days were estimated to be 0.35 and 1.3 kg s-1, respectively. The latter rate is comparable to the largest single, industrial source of sulfur in the Pacific Northwest. A significant increase in the emission of sub-micron aerosols was also observed between March 27 and June 30. Small aerosol particles are produced in the plume of effluents, probably by gas-to-particle conversion, at a rate of about 2¿1017 s-1. However, the concentrations of cloud condensation nuclei and ice nuclei in the plume are comparatively small. Aerosols in the plume, greater than about 1 &mgr;m in diameter, consist predominantly of Al, Si, S, K and Ca. Some of the aerosols which were collected in the plume on June 30 might have been Pele's hairs, which are a sign of new magmatic activity. (Volcanoes, aerosols, particles, gases)