Volcanoes are to be taken seriously. This sign shows the current amount of poisonous gases in the air. When I arrived, the red lamp running was alight, and the platform by the crater edge was closed. They are measuring continuously, and after a while they opened all areas.

Beside this sign, there was a speaker voice that kept on nagging a warning about poisonous gases, and that people with asthma should not be there at all. The message was in Japanese, English, Chinese and Korean. The English voice was a bit unexpected. Normally when they have recorded voices in Japan, it's in American English. But in this case it was a lass who spoke British English, but not the regular Received Pronunciation, but she had a clear working-class accent.