A case of suffocation by an advertising balloon filled with pure helium gas.

We encountered a rare case of suffocation by an advertising balloon filled with pure helium gas. Suffocation caused by inhalation of atmosphere lacking in oxygen is not exceptional, but reports of death by suffocation due to a pure inert gas such as helium are very rare. In this case, the balloon mooring on the ground was enclosed, warning signs were displayed, and it was clear that entering the balloon filled with an atmosphere lacking in oxygen was extremely dangerous and should not be done; the accident did, however, occur. Accidents of this kind may occur in the future unless appropriate education and countermeasures are taken.