The Japan International Exposition Association (Expo Association) announced that the explosion accident that occurred during the venue construction for the 2025 Osaka-Kansai Expo was due to the failure to measure the gas concentration before work. In locations where there is a risk of high concentration, the manual will be revised to thoroughly measure the concentration, and certain suspended construction work will resume on April 22nd. The accident occurred on March 28th when a spark from welding work ignited gas and caused damage to a part of the concrete floor near an outdoor event plaza toilet.