Aerosol number concentrations and trace gases (SO₂, O₃, HCHO, and H₂O₂) were measured over Imizu City, Toyama Prefecture, Japan on August 5, 2020, from a helicopter. The concentrations of fine particles (0.3-0.5 μm) were high at ground level and at an altitude of approximately 1200 m due to the volcanic plume from Nishinoshima. However, concentrations of aerosol particles were low at an altitude of approximately 2400 m. The volcanic plume did not significantly affect the lower free troposphere. High concentrations of SO₂ were also observed. The H₂O₂ concentrations (0.27-0.56 ppb) were much lower than those during previous observations in the summer (2.0-6.7 ppb) and significantly lower than the SO₂ concentrations (1.8-3.3 ppb). The concentrations of HCHO (2.1-2.5 ppb) were higher than those of H₂O₂. The oxidation of S(IV) to H₂SO₄ in cloud water might have been suppressed over the studied area.

2020年8月5日，日本直升飞机在日本富山县Imizu市测量了气溶胶浓度和痕量气体（SO ₂，O ₃，HCHO和H ₂ O ₂）。由于来自西之岛的火山羽流，在地面高度和大约1200 m的高度，微粒浓度（0.3-0.5μm）高。但是，在大约2400 m的高度，气溶胶颗粒的浓度较低。火山羽并没有明显影响较低的对流层。还观察到高浓度的SO ₂。H ₂ O ₂浓度（0.27-0.56 ppb）远低于夏季以前的观测值（2.0-6.7 ppb），并且显着低于SO ₂浓度（1.8-3.3 ppb）。HCHO（2.1-2.5 ppb）的浓度高于H ₂ O ₂的浓度。在研究区域内，云水中的S（IV）氧化为H ₂ SO ₄可能已被抑制。