A 13-year-old boy fell to his death from an HDB block in an accident when he was having a "laughing gas'' session with two classmates.

State Coroner Marvin Bay found the teen's death at Block 24, Bendemeer Road, on May 25 this year to be a "tragic misadventure".

The teen, who had been inhaling butane - which is used in gas canisters and lighter fluid - fell eight floors and was pronounced dead at 6.40pm.

The teen's body, clad in his school uniform and blue socks without footwear, was found on the second-floor ledge of the block. The three boys had their "laughing gas'' session at an open space near a lift lobby on the 10th level.

In his findings yesterday, Coroner Bay said the teen's death is a sobering reminder of the harm that can result from butane abuse, which is a form of inhalant abuse.

"(His) fall appears to have been precipitated by his risk-taking behaviour induced by his euphoric state from butane abuse,'' he said.

Butane gas inhalants enter through the pulmonary system, and immediately enter the blood supply and can produce intoxication within seconds.

The acute effects of inhalant abuse include dizziness, increased heart rate, impaired coordination, disorientation and confusion.

Inhaling hydrocarbons such as butane, isobutane and propane would likely cause a wide range of neurological symptoms.

The coroner said both butane abuse and toluene abuse or glue sniffing can cause serious physical and psychological dependence.

"As a result of their easy availability from industrial use, both forms, toluene glue and butane gas abuse, can be 'gateway' abuse substances that can lead to experimentation and eventual abuse with ever more serious narcotic substances and 'hard drugs'," he said.

They also lead abusers to acts of self-harm, whether deliberate or accidental, while under the influence of the substance concerned.

The teen, described by his girlfriend as a happy but playful person, had "no suicidal thoughts, stressors from school work" nor was he bullied in school.

The coroner said there was no evidence to suspect foul play. After a thorough investigation, there was also nothing to support a claim by the teen's mother, who is in a drug centre, that her son had been assaulted on the day of his death.

Investigations showed that the teen and his classmates had stolen three canisters of Ronson Universal lighter refill from a sundry shop in Bendemeer Road for the "laughing gas" session.

This entailed repeatedly spraying the gaseous contents of the canister into a plastic bag or bundled shirt, and inhaling the contents of the canister from the opening of the plastic bag or shirt, through the mouth, to achieve a "high" state of mind.

The teen had been jumping around and laughing to himself from inhaling the butane on his shirt, the court heard. His classmates saw him sit on the ledge, facing outwards with his legs dangling. Suddenly, his left hand slipped and he fell off his perch. He lost his grip while holding onto the outside wall and fell, the court heard.