An explosives expert has been unable to find any literature warning that smoke created by a fireworks display could cause traffic disruption, an inquest heard today.
Christopher Case was commissioned by police to investigate whether a fireworks display on the night of one of Britain's worst motorway pile-ups had any bearing on the crash.
He said he had read literature about firework safety, including material provided by the Health and Safety Executive, but had seen nothing warning of the dangers of smoke from fireworks to motorists.
Seven people died and 51 people injured during a series of crashes between 34 vehicles on the southbound carriageway of the M5 near Junction 25 on the evening of November 4 2011.
The collision happened at 8.20pm, just five minutes after a £3,000 fireworks display concluded 200ft away at Taunton rugby club.
Motorists have told of entering a wall of thick fog - described by some as a "white curtain" or "emulsion" - and were unable to prevent multiple collisions. Other drivers have described smelling smoke or gunpowder on the motorway.
Mr Geoffrey Counsell, 51, had been operating the display at the rugby club. He was cleared of breaching health and safety laws on the night of the accident.
Mr Case, who works for Merseyside Fire Service, told the inquest how he accompanied police to Mr Counsell's home two days after the incident and later went to a farm where he kept fireworks in a shipping container.
But Mr Case said he found it unusual that Mr Counsell did not have a pre-planned firing order for the display at the rugby club.
The inquest also heard from members of the emergency services, who were first on the scene of the crash - arriving with six minutes of the first 999 call being made.
John Dyer, from the South West Ambulance Services NHS Foundation Trust, said a total of 42 ambulances attended the crash scene to assist the injured.
William Harvison, from the Devon and Somerset Fire Service, said that within 25 minutes of the accident it had been declared a major incident.