Fireworks operators need more training on how humidity and bonfire smoke can be hazardous to motorists to prevent a repeat of one of Britain's worst motorway pile-ups, a coroner has said.
West Somerset Coroner Michael Rose said he had written to the Government and several public authorities calling for the licensing of firework display operators for a period of five years.
He also said that fog detection equipment should be installed along the stretch of the M5 near Taunton, Somerset where seven people died and 51 were injured during a series of crashes involving 34 vehicles.
Motorists said they entered a wall of thick fog - described by some as being like a "white curtain", "emulsion" or "custard being poured from a jug" - and were unable to prevent multiple collisions.
The collision happened on the southbound carriageway at 8.20pm on November 4 2011, just five minutes after a £3,000 fireworks display concluded only 200ft away at Taunton rugby club.
Grandparents Anthony Adams, 73, and his wife Pamela, 70, from Newport, South Wales; Michael Barton, 67, and his daughter Maggie, 30, from Windsor, Berkshire; battle re-enactor Malcolm Beacham, 46, from Woolavington, Somerset; and lorry drivers Terry Brice, 55, from South Gloucestershire, and Kye Thomas, 38, from Cornwall, all died.
Last year firework contractor Geoffrey Counsell, 51, who had been operating the display at the rugby club, was cleared at Bristol Crown Court of breaching health and safety laws on the night of the accident.
Concluding an inquest in April, Mr Rose said smoke from the fireworks display did not cause the pile-up but said it may have mixed with fog to further reduce vision - creating "an area of reduced visibility".
The coroner said he had concerns but before making any formal recommendations he wanted to hear first from the Department of Business, Innovation and Skills, the Health and Safety Executive, the Highways Agency, the British Pyrotechnics Association and Taunton Deane Borough Council.
Having heard evidence last week, Mr Rose said today he had written a report under Regulation 28 of the Coroner's Rules to prevent further deaths.
He said he had sent copies to the Department of Transport, the Department of Business, Innovation and Skills, the Highways Agency and the Health and Safety Executive.
Mr Rose has already secured a commitment from the Highways Agency to install more warning signs between junctions 23 and 25 alerting motorists of dangers ahead when traffic is slowing down.
But he said this offer - subject to funding - did not go far enough.
"These proposals whilst possibly preventing further vehicles entering an accident scene or a large area of reduced visibility would not have prevented the initial incident and that this can only be achieved by the erection of fog detection devices and greater use of overhead gantries displaying signs warning of events that may cause reduced visibility," Mr Rose said.
"And as the criterion for deploying road safety equipment is six personal injury collisions in three years the present incident would not qualify for special consideration."
Mr Rose said he was also recommending that City and Guild qualifications for firework operators give training on recognising the risks of holding a display during "very high humidity".
"And before operating any display firers had prepared a risk assessment which took account of the topography of the area, nearby watercourses, prevailing wind conditions, identifying highways and all other matters relevant for the safety of the users thereof onlookers and nearby residents," he said.
"Assessed the humidity, wind direction and speed immediately before the display; positioned lookouts to see if any smoke or fog was approaching a highway or railway line in the immediate vicinity.
"Had immediate access to a communication link to the emergency services and; be able to stop the display immediately if an emergency arises and to consider whether firers and senior firers should be licensed by law for periods of five year.
"And whether the local licensing authorities shall advise persons holding firework displays of the risks referred to herein."
The authorities have 56 days to reply to Mr Rose's report.