Airborne measurements of particle and gas emissions have been obtained in paroxysmal, intraeruptive, posteruptive, and extrareuptive emissions from six volcanoes. The paroxysmal and intraeruptive emissions contained relatively few small particles (<0.1 μm in size) and little gaseous sulfur in comparison to the posteruptive and extraeruptive emissions. The majority of the SO2 injected in the atmosphere (?0.01 Tg) by the 1976 eruption of Saint Augustine probably occurred during the intraeruptive and posteruptive stages. The paroxysmal eruptions of Saint Augustine produced about 6 Tg of particles of 0.01-66 μm in size and about 0.2 Tg of particles 0.01-5 μm in size. An additional 0.05 Tg of 0.01- to 5-μm sized particles were emitted during the posteruptive and intraeruptive periods. Estimated emission rates from the six volcanoes ranged from 3¿102 to 5¿10-4 kg s-1 (SO2), 4¿10-1 to 2¿10-4 kg s-1 (H2S), 1¿105 to 1¿101 kg s-1 (water vapor), 6¿105 to 2¿10-5 kg s-1 (particulate mass), 6¿1019 to 3¿1014 s-1 (condensation or Aitken nuclei), and 2¿1018 to 1¿1016 s-1 (cloud condensation nuclei). The impacts of these new measurements on previous estimates of worldwide particle and gas emissions from volcanoes are discussed.