An engineer who was trying to light two aromatherapy diffusers in his master bedroom toilet unknowingly ignited vapours from an essential oil, causing a flash fire, a coroner's court heard yesterday.

Mr Mohammad Rizalludin Hassan, 34, suffered second-degree burns to 80 per cent of his body from the blaze last year. He died in hospital nine days later.

Details of the Oct 13 fire emerged on the first day of the coroner's inquiry into his death.

Mr Rizalludin went to light the Avita diffusers at about 9.30pm. Shortly after, his wife and mother-in-law, who were in the master bedroom, heard a loud explosion.

Mother-in-law Juraidah Nabi, 53, saw a 1m trail of fire on the floor. She and her daughter, Ms Nurul Asyikin Norman, 34, then saw Mr Rizalludin engulfed in flames. Both women smothered the flames with blankets and Madam Juraidah called for an ambulance.

Mr Rizalludin, whose body was red and bleeding, began pacing around the living room to ease his pain. He could not see clearly and found it hard to breathe.

A neighbour used a hose from the kitchen toilet to spray water on Mr Rizalludin, but this made him scream in agony.

He was taken to the National University Hospital and, the next day, sent to the Singapore General Hospital's burns unit, where he underwent cadaveric skin and bone grafts, among other procedures.

But on Oct 20, he got pneumonia, acute respiratory distress syndrome and hypotension, and his condition gradually worsened.

A fire investigator said the blaze started on the vanity top in the toilet, where the diffusers and two lighters were kept. The remnants of a 5l bottle of essential oil was found on the toilet floor. The lowest temperature at which the liquid's vapours will ignite is 16 deg C, he added.

The inquiry also heard that the diffusers' brand owner, Shiang's International, required buyers to attend a safety briefing. But Ms Nurul Asyikin, who bought the first diffuser 1½ years ago, said she was never told of the briefing.

After the fatal fire, the company put up a safety video on its website.

One previous accident with the diffuser, which it released in 2007, was recorded in 2014 when a staff member suffered minor burns.

Shiang's operations manager Chok Wai Chen will testify when the inquiry resumes at a later date.