On April 6th, methane gas exceeding the explosive concentration threshold (5 vol%) was detected in an outdoor underground electrical equipment pit located in the "Green World" area on the west side of the Osaka-Kansai Expo site. The gas was discovered using a detector brought in by a visitor and was reported to the Osaka City Fire Department. Access to the area was immediately restricted, and after approximately one hour of ventilation, the gas concentration dropped below the standard safety level. In fact, a similar explosion incident occurred in this same section last year, prompting the Expo Association to implement countermeasures such as installing ventilation systems and conducting regular inspections. In response to the recent incident, the association is strengthening its monitoring system by increasing both the frequency and number of measurement points. The association stated, “Although there is no immediate danger, we will continue to take thorough measures to ensure safety.”

4月6日、大阪・関西万博の会場西側「グリーンワールド」エリアにある屋外の電気設備地下ピットで、爆発の危険がある濃度（5vol%）を超えるメタンガスが検出された。これは、来場者が持ち込んだ検知器で発見され、大阪市消防局に通報されたもので、現場はすぐに立ち入りが規制され、約1時間の換気によって基準値を下回った。実はこの区画では昨年も同様の爆発事故が起きており、博覧会協会はすでに換気装置の設置や定期的な測定などの対策を講じていた。今回の件を受け、測定回数や測定箇所を増やすなど、モニタリング体制の強化を進めている。協会は「直ちに危険な状態ではないが、安全確保のため今後も万全の対策を講じていく」としている。