MOST people would speak of a nightmare but for Dave Pearson, the effects of being poisoned by sarin nerve gas resembled a more mundane experience.
"Try to imagine it like this," he says: "the world's worst ever hangover. When they let me out of hospital, I slept for a few hours and then woke up with a raging headache. I couldn't focus on close objects, and my pupils were like pinpricks - my kids nicknamed me the Alien. Think of the worst hangover you've ever had, and then add a bit more. This went on for a fortnight. Not a pleasant experience."
This is the understatement of a lifetime. A year ago yesterday Mr Pearson, in his own words, "entered the history books for a few nanoseconds" when he became the only British victim of the Tokyo subway attack. Just after 8 a.m. on March 20th, 1995, he was commuting from his family's apartment in western Tokyo to the offices of Australia's Westpae Banking Corporation where he works as chief manager. After one stop, people in his carriage started coughing. Mr Pearson noticed "a faint, sweet, plastic kind of smell".
The train was crowded and at the next station he had to step off to make way for disembarking passengers. "It was then that I realised that something was wrong. They were carrying an old man off the carriage in front, and laying him on the platform. He was lying there with his arms and legs convulsing, and there were people all around him sitting on the floor looking very unwell."
The old man died soon after, one of the victims of the most bizarre and shocking terrorist attacks in Japanese history. Half an hour before, 10 members of the Aum Shinri Kyo cult had boarded five separate trains, carrying plastic bags filled with the liquid form of sarin, a nerve gas first developed by Nazi scientists during the second World War. Travelling in pairs, they punctured the bags with sharpened umbrellas before jumping off.
The motives remain obscure the cult's leader, Shoko Asahara, who will finally go on trial next month, had for years been predicting an Apocalypse and acquiring huge stocks of chemical and biological weapon ingredients with the aim, it appears, of hurrying it along. Apart from the 12 dead, 5,500 people were poisoned by the sarin. Three of them are still unconscious, and will probably never wake up.
By some lucky instinct, Mr Pearson remained on the platform while the train moved off - by the time it reached the next station, Kasumigaseki, the gas had permeated his carriage and dozens of passengers had begun fainting, bleeding through the nose, and foaming at the mouth. Still feeling fine, he made his way to the surface, "and after that I don't remember a great deal. My vision was going; it was like looking through a haze. I felt very nauseous, and on the verge of fainting."
Somehow he struggled into a cab, and made it to the office. His colleagues took him to hospital where he spent the rest of the day. His wife visited him and the following morning she, too, was sick, after absorbing traces of the nerve gas from his clothes and hair. But within two weeks, Mr Pearson returned to work; the hangover appeared to have faded.
A month after the attack he woke up in the middle of the night, trembling and hyperventilating. The panic attacks came every couple of weeks.
According to Dr Kanzo Nakano, a psychiatrist at St Luke's International Hospital, 20 per cent of the sarin victims are still suffering from symptoms of post traumatic stress disorder.
Mr Pearson's last panic attack was in January. He has received counselling but is assured that after the mental recovery, there will be no long term health risks.