Potentially explosive methane gas level logged at Japan's Osaka Expo venue
A potentially explosive level of methane gas was detected at the World Exposition venue in Osaka less than a week before the event's opening on Sunday, prompting the organizer to step up safety measures, Kyodo reports.
The Japan Association for the 2025 World Exposition said flammable gas exceeding safety limits was discovered on Sunday in an underground space for electrical equipment in the Green World construction area on the artificial island of Yumeshima.
When the covering was opened for ventilation, the gas concentration fell below safety standards. The day marked the final rehearsal to check facility operations and traffic flow with visitors, ahead of the event's opening.
In a bid to prevent an accident, the organizer will more frequently monitor gas levels and install fences to restrict access. Built on reclaimed land, the venue has areas where methane is generated due to buried waste beneath the surface.
Safety concerns over the accumulation of methane gas at the venue have lingered since an explosion in March 2024, when sparks from welding work ignited flammable vapor from underground. The incident caused no injuries but damaged parts of the site.
It is worth noting that the Osaka Expo roof is recognized as the world's biggest wooden structure.