Relations between volcanic activity and environmental problem, global or regional, were discussed generally. It was emphasized that, among the volcanic products, volcanic gas and fine volcanic ash are most important as pollution substance, as shown as follows : 1st. Both in these volcanic products and usual smokes from factories, common chemical constituents are contained. For instance, they are HF, HCl, SO₂, H₂S, heavy metals and derived constituents of them. 2nd. Amounts of volcanic gas or fine volcanic ash discharged from the crater in active stage are not so small as usually considered. In spring of 1975, the season in which the activity of the volcano was rather high, mass flow of SO₂ discharged from the crater of Sakurajima Volcano reached to the level of about 1100 tons per day. So the total amounts of volcanic gas might be tremendous. Furthermore, it was estimated that for twenty years, about 1×10⁸ tons of fine volcanic ash was discharged from the volcano. 3rd. The residence time of volcanic gas and fine volcanic ash in the atmosphere is rather long as compared with other volcanic products. And these volcanic products, volcnaic gas and fine volcanic ash, may be carried and travel very far from the effusing point. Effects caused by them are long and wide. Especially in the near places of the volcano, effects and influences are often serious as Kogoshima City near Sakurajima. In future, the total amounts of these volcanic products discharged from whole active volcanos in the world must be estimated more accurately. If so, the evaluation of influences of volcanic activity for the global environment may be possible more quantitatively. And, suitable air pollution monitoring system set around the active volcano is conisdered to be quite effective for this purpose.