Earlier this month, the Tokyo branch of the Fund for Local Government Employees' Accident Compensation made the certification decision, concluding that it was reasonable to regard the man, in his 60s, as having developed depression as a result of the sarin attack, the sources said.

In the incident, which occurred in March 1995, the Aum Shinrikyo doomsday cult released deadly sarin nerve gas on the Tokyo subway system, killing 13 people and injuring more than 6,000 others. Many of the injured still suffer from physical and mental problems.

According to an attorney representing the man, it is rare for an illness that did not develop soon after the sarin attack to be certified as a commuting injury.

The man, who was a hospital staff member at the time, experienced the sarin attack on his way to work on a Tokyo subway line.

After being hospitalized for four days, he returned to work but continued to suffer such symptoms as blurry vision and fatigue.

He was diagnosed with depression in 1999 and was hospitalized later. Eventually, he was forced to take early retirement.

Although the man filed for certification as a commuting accident victim in 2008, a screening panel of the compensation fund's Tokyo branch did not recognize a causal link between his illness and the sarin attack.

In 2015, he filed a complaint against the judgment and submitted documents prepared by his doctor on the results of a follow-up study about the after-effects of sarin poisoning, winning certification as a commuting accident victim this month.

"He was certified probably because we could prove that the after-effects became chronic and developed into depression," said the man's doctor, Nippon Medical School Prof. Yoshiro Okubo.

According to the Recovery Support Center, a nonprofit organization that continues health studies on sarin attack victims, more than half of survey respondents claim that they still suffer blurry vision or fatigue more than 20 years after the incident. (Jiji Press)