Japanese government and local officials have conducted a water quality survey at the US military's Yokota Air Base in western Tokyo. This comes after possible leakage of water containing toxic substances from the base.



PFAS is a group of organic fluorine compounds. In August last year, it was found that water containing PFAS chemicals, including PFOS and PFOA, which are considered potentially harmful, had likely leaked from the air base. Authorities have been investigating the incident.



On Wednesday, officials of the Defense Ministry, Tokyo Metropolitan Government and surrounding municipalities took samples from a reservoir on the air base to check the water quality. An accord of the Japan-US Status of Forces Agreement allows Japanese officials to survey potential environmental damage at US bases in Japan.



The Defense Ministry said more than 1.5 million liters of water containing PFOS and other chemicals remain on the air base, including in the reservoir. Ministry officials said the US side has explained that toxic substances would be removed with a decontamination system.



The officials said the water samples will be analyzed over the next two weeks. If the PFAS levels are below the government's provisional limit for tap water of 50 nanograms per liter, the treated water will be released through drains at the southwestern side of the air base.



The Defense Ministry said that it will swiftly provide detailed explanations to people in relevant municipalities.