Nearly 2,500 people could come into contact with the deadly nerve agent novichok if it were used to attack someone at Heathrow Airport, industry experts have warned.

Bruhn NewTech, a technology company that develops software aimed at increasing protection against airborne threats or attacks, looked at what would happen if the assassination attempt on former Russian double agent Sergei Skripal and his daughter was scaled up to an attack on a target on their way to catch a flight from Heathrow terminal five.

Heathrow is considered to be particularly vulnerable because it is the second busiest airport in the world, by international passenger traffic, and could facilitate the rapid spread of contamination from a chemical weapons attack if the incident was not identified and contained quickly enough.

An attack at the airport “would be catastrophic”, Dr Simon Bennett, director of the Civil Safety and Security Unit at the University of Leicester, told The Independent. Dr Bennett, who specialises in aviation security, said Heathrow was a “prime site” for such an attack due to its status as a totem, similar to Westminster, the London underground or the UK’s railway stations.

Commenting on the company’s scenario, Dr Bennett said the contamination trail would be “very extensive” and could lead to the closure of the entire terminal, “not just for days but potentially for weeks”. He described novichok, which is thought to have been smuggled into Britain through an airport in a “discreet” container, as “so pernicious and so persistent”.

He added: “These weapons, potentially in the hands of wrongdoers, are very effective, not only in terms of killing and injuring but in terms of terrorising and causing real long-term economic damage.”

Bruhn NewTech, which sells chemical, biological, radiological and nuclear information management software, said if a chemical attack were to take place at Heathrow, around 900 people would need to be hospitalised and more than 9,000 people would be asked to disinfect their belongings, such as clothing and jewellery.

The technology company said their calculations were conservative, as they do not include employees at the airport, do not take into account the potential that novichok could spread to other terminals, or the potential spread of the nerve agent to other countries if contaminated passengers were able to reach other airports before authorities were able to contain the incident.

Novichok poisoning: Charlie Rowley reveals perfume gift he gave to partner contained deadly poison

During the attack on Mr Skripal and his daughter they came into contact with novichok on the morning of 3 March, before travelling by car to the Maltings shopping centre in Salisbury.

They then went to the Bishops Mill Pub in the town centre and dined at the nearby Zizzi. The emergency services were called around 4.15pm when the pair were discovered unconscious on a bench in the centre of Salisbury. Detective Sergeant Nick Bailey, who had been sent to the Skripals’ house, also fell ill after attending the scene.

Four months later, and after the Skripals and the detective had been discharged from hospital, two members of the public were poisoned by the same sort of nerve agent eight miles away in Amesbury. Dawn Sturgess, a mother of three, died eight days after she sprayed an “oily” substance she believed to be perfume on her wrists, while her partner, Charlie Rowley, recovered and was later discharged from hospital.

By looking at the timeline of the poisoning in Salisbury, Bruhn NewTech estimated what would happen if a similar attack took place on a victim travelling to Heathrow before passing through airport security, going to a pub and restaurant and then being found unconscious in terminal five, the airport’s busiest terminal.

“The effect would be massive,” Erik Juel Ellinghaus, director of the company, told The Independent. He said it could also be fatal if a large quantity of the agent was used on the target, or if it was part of a terror attack aimed at causing mass casualties.

Mr Juel Ellinghaus said the spread of contamination would start “immediately” and continue “as long as anyone touches the oily, colourless substance and transfers it by touching someone or something. The realisation that something is wrong could be hours after the event started.”

By then, thousands could have come into contact with the nerve agent and spread it further before succumbing to its effects.

Skripal attack aftermath – in pictures Show all 15 1 /15 Skripal attack aftermath – in pictures Skripal attack aftermath – in pictures Scene of attack Members of the emergency services in hazard suits fix the tent over the bench where Sergei and Yulia Skripal were found unconscious on a park bench in Salisbury in March 2018. Getty Skripal attack aftermath – in pictures Victim - Sergei Skripal The retired Russian colonel and former double agent for MI6 was in a critical condition in hospital for more than two months after being exposed to novichok in Salisbury. He was given refuge in the UK after being jailed in Moscow for treason. Mr Skripal came to Britain as part of a high-profile “spy swap” in 2010 in which four men were exchanged for ten Russian "sleeper agents" in the US. In this image he is speaking to his lawyer from behind bars in Moscow in 2006. AP Skripal attack aftermath – in pictures Victim - Yulia Skripal Yulia Skripal was struck down by a novichok poison alongside her father Sergei. Facebook Skripal attack aftermath – in pictures Scene of attack A police officer stands guard outside a branch of the Italian chain restaurant Zizzi where the pair dined at before falling ill. It was boarded off whilst investigators worked on the building and later found traces of the chemical weapon within it. AFP/Getty Skripal attack aftermath – in pictures Scene of attack Large areas of central Salisbury were cordoned off by police following the discovery of the Skripals. Traces of nerve agent were also found in The Mill pub. PA Skripal attack aftermath – in pictures Victim - Nick Bailey Detective Sergeant Nick Bailey, rushed to the aid of the Russian ex-spy and his daughter who were targeted with a nerve agent. He was hospitalized after aiding them and didn't leave until three weeks after the attack. Wiltshire Police/Rex Skripal attack aftermath – in pictures Police investigation - Skripal’s home Police believe they were poisoned at home, and detectives found the highest concentration of novichok on the front door of Mr Skripal’s house. Getty Skripal attack aftermath – in pictures Theresa May visits scene of attack Britain's Prime Minister Theresa May spokes with Wiltshire Police's Chief Constable Kier Pritchard near where the Skripal's were found. Britain expelled 23 Russian diplomats over the nerve agent poisoning and suspended high-level contacts, including for the World Cup on March 14. Theresa May told parliament that Russia had failed to respond to her demand for an explanation on how a Soviet-designed chemical, Novichok, was used in Salisbury. AFP/Getty Skripal attack aftermath – in pictures Skripal days before attack Sergei Skripal days before he was exposed to Novichok, that has left him fighting for life. ITV News Skripal attack aftermath – in pictures Police investigation - military involvement British soldiers were deployed soon after the attack to help a counter-terrorism investigation into the nerve agent attack. One of the places they were asked to help out with was Skripal's home and it's surrounding. They were asked to remove a vehicle connected to the agent attack in Salisbury, from a residential street in Gillingham. AFP/Getty Skripal attack aftermath – in pictures Police investigation Personnel in protective coveralls and breathing equipment cover an ambulance with a tarpaulin at the Salisbury District Hospital. AFP/Getty Skripal attack aftermath – in pictures Police investigation The investigation extended to the grave of Sergei Skripal's son Alexander in London Road cemetery. Getty Skripal attack aftermath – in pictures Police investigation The Counter Terrorism Policing Network requested assistance from the military to remove a number of vehicles and objects from Salisbury. EPA Skripal attack aftermath – in pictures Home Secretary visits scene of attack Home Secretary Amber Rudd visited the scene of the nerve agent attack at the Maltings shopping centre on 9 March. Getty Skripal attack aftermath – in pictures Yulia Skripal speaks for the first time Yulia Skripal, speaking for the first time, said she felt lucky to have survived the nerve agent attack in Salisbury which left her fighting for life. Ms Skripal said her life had been “turned upside down” by the assassination attempt. But the Russian national added she hoped to return to her homeland one day, despite the Kremlin being blamed for the attack. Reuters

He said the response would depend “on how quickly the situation is determined to even be a chemical attack. Closing down the terminal completely and decontaminating everyone would be an option if the target gets ill soon after the attack. But if the effect is delayed it will be too late to contain the situation.”

The nerve agent could even be spread to other countries if contaminated passengers catch their flights before a major incident is declared. “This can only be prevented if the target falls ill within a short time and the medical staff react very quickly, realising that this is not an ordinary illness, and take steps to quarantine the airport. If the effect is delayed, the contaminated passengers will obviously have travelled to their destinations worldwide,” Mr Juel Ellinghaus cautioned.

In some scenarios, containing an attack by a chemical such as novichok would be “virtually impossible”, he said. “Since the first indication of the attack can be many hours after the event, containment would involve tracing the steps of every passenger that could have been contaminated and sealing off the areas all these people could have touched.”

Authorities would then need to go through the areas with detection equipment and decontaminate them if required.

Amesbury major incident after couple exposed to novichok Show all 40 1 /40 Amesbury major incident after couple exposed to novichok Amesbury major incident after couple exposed to novichok Forensic investigators, wearing protective suits, emerge with bagged evidence from the rear of John Baker House in Salisbury, after it was confirmed that two people living in Amesbury had been poisoned with the nerve-agent Novichok. Reuters Amesbury major incident after couple exposed to novichok Dawn Sturgess, a mother-of-three from Durrington, died after being exposed to novichok Facebook Amesbury major incident after couple exposed to novichok British police are scouring sections of Salisbury and Amesbury in southwest England, searching for a container feared to be contaminated with traces of the deadly nerve agent Novichok. Reuters Amesbury major incident after couple exposed to novichok Officers hope that Charlie Rowley, whose partner Dawn died in hospital, can help them establish how the couple came to be contaminated AFP Amesbury major incident after couple exposed to novichok An investigator in a chemical suit works behind screens erected in Rollestone Street PA Amesbury major incident after couple exposed to novichok Fire and Rescue Service personel arrive with safety equipment at the site of a housing estate on Muggleton Road, after it was confirmed that two people had been poisoned with the nerve-agent novichok, in Amesbury Reuters Amesbury major incident after couple exposed to novichok Forensic investigators at John Baker House Reuters Amesbury major incident after couple exposed to novichok Police and military personnel seized a car from a quiet residential street in Swindon as part of their ongoing investigations into the nerve agent incident in Salisbury and Amesbury SWNS Amesbury major incident after couple exposed to novichok Emergency workers in military protective suits search the fenced off John Baker House AP Amesbury major incident after couple exposed to novichok A forensic investigator, wearing a protective suit, emerges from the rear of John Baker House, after it was confirmed that two people had been poisoned with the nerve-agent Novichok, in Amesbury, Britain, July 6, 2018. REUTERS/Henry Nicholls HENRY NICHOLLS Reuters Amesbury major incident after couple exposed to novichok Forensic investigators at John Baker House Reuters Amesbury major incident after couple exposed to novichok Emergency services arrive at John Baker House EPA Amesbury major incident after couple exposed to novichok Dorset Fire and Rescue Service at the house PA Amesbury major incident after couple exposed to novichok Tents set up by search teams are seen at the end of Rollestone Street, outside the John Baker House for homeless people in Salisbury. British police are scouring sections of Salisbury and Amesbury in southwest England, searching for a container feared to be contaminated with traces of the deadly nerve agent Novichok. AP Amesbury major incident after couple exposed to novichok Dorset Fire and Rescue Service at the house in Muggleton Road PA Amesbury major incident after couple exposed to novichok Fire and Rescue Service safety equipment Reuters Amesbury major incident after couple exposed to novichok Police activity at the house in Muggleton Road PA Amesbury major incident after couple exposed to novichok Emergency services arrive at John Baker House EPA Amesbury major incident after couple exposed to novichok Fire and Rescue Service safety equipment PA Amesbury major incident after couple exposed to novichok Police tents are erected outside a residential address in Amesbury, southern England, on July 6, 2018 where police reported a man and woman were found unconscious in circumstances that sparked a major incident after contact with what was later identified as the nerve agent Novichok. Police on July 6, 2018, raced to find the object that contaminated a British couple with the Soviet-made Novichok nerve agent in southwestern England where a former Russian spy was poisoned with the same toxin four months ago. / AFP PHOTO / Chris J RatcliffeCHRIS J RATCLIFFE/AFP/Getty Images CHRIS J RATCLIFFE AFP/Getty Amesbury major incident after couple exposed to novichok Emergency services arrive at the house in Muggleton Road in Amesbury PA Amesbury major incident after couple exposed to novichok Members of the emergency services at the house in Muggleton Road PA Amesbury major incident after couple exposed to novichok Gas masks AFP/Getty Amesbury major incident after couple exposed to novichok Forensic tents outside John Baker House on Rolleston Street, Salisbury, Wiltshire, where counter-terrorism police are investigating after a couple were left in a critical condition when they were exposed to the nerve agent Novichok. PRESS ASSOCIATION Photo. Picture date: Friday July 6, 2018. Dawn Sturgess, 44, and Charlie Rowley, 45, were taken ill on Saturday in Amesbury, around eight miles from where former Russian spy and his daughter were poisoned with the same substance in Salisbury in March. See PA story POLICE Amesbury. Photo credit should read: Yui Mok/PA Wire Sam Blewett PA Amesbury major incident after couple exposed to novichok Fire and Rescue Service personel prepare safety equipment Reuters Amesbury major incident after couple exposed to novichok Police investigators arrive at the site of a housing estate on Muggleton Road Reuters Amesbury major incident after couple exposed to novichok A police officer stands guard behind the housing estate REUTERS Amesbury major incident after couple exposed to novichok Police on the scene Getty Images Amesbury major incident after couple exposed to novichok The couple remain in a critical condition at Salisbury District Hospital AFP/Getty Amesbury major incident after couple exposed to novichok In March Russian former spy Sergei Skripal and his 33-year-old daughter Yulia were poisoned with the Russian-made Novichok in the town of Salisbury. British Prime Minister Theresa May has accused Russia of being behind the attack on the former spy and his daughter, expelling 23 Russian diplomats in retaliation Getty Images Amesbury major incident after couple exposed to novichok British police are cordoning off places the people are known to have visited before falling ill EPA Amesbury major incident after couple exposed to novichok British police officers stand outside a residential property in Amesbury AP Amesbury major incident after couple exposed to novichok Deputy Chief Constable of Wiltshire Police Paul Mills makes a statement to the press outside The Bowman Centre after Wiltshire Police declared the situation a major incident Getty Amesbury major incident after couple exposed to novichok Amesbury Baptist Centre PA Amesbury major incident after couple exposed to novichok Amesbury resident Sam Hobson, speaks to assembled press outside Amesbury Baptist Centre claiming to be a friend of the man and woman exposed to an unknown substance Getty Amesbury major incident after couple exposed to novichok The pair were found unconscious at an address in Muggleton Road, Amesbury Getty Amesbury major incident after couple exposed to novichok Police cordon at Queen Elizabeth Gardens in Salisbury. The town is around 10 miles from Salisbury where former Russian spy Sergei Skripal and his daughter Yulia were poisoned in a suspected nerve agent attack PA Amesbury major incident after couple exposed to novichok Deputy Chief Constable of Wiltshire Police Paul Mills makes a statement Getty Amesbury major incident after couple exposed to novichok Police officers stand outside Boots pharmacy, near to the Barcroft Medical Centre in Amesbury PA Amesbury major incident after couple exposed to novichok Amesbury Baptist Centre PA

One worst-case scenario would be a botched attempt to use a nerve agent, Mr Juel Ellinghaus said, giving the example of a target wearing gloves, who would continue to touch and contaminate objects before falling ill hours later.

Another would be “a terrorist attack that is actually aiming at creating mass casualties”, such as the sarin attack on the Tokyo underground by members of the Aum Shinrikyo cult, which killed 13 people and injured more than 1,000.

“If we are considering novichok, the worst case would be the deliberate placement of the agent in places that many people touch – or in something that many people apply to their skin,” Mr Juel Ellinghaus said.

“The history of terrorism shows us that the locations with the highest number of people are the main targets. So, as I see it, some of the main potential targets are football stadiums, concert arenas, museums, cruise ships and of course other airports such as Gatwick.”

He added: “Similar threats from terrorists are not just chemical, but also biological or radiological. Some examples are the recent events in France and Germany where terrorist plots involving homemade ricin was uncovered and fortunately stopped by police.”

Mr Juel Ellinghaus said he is concerned not enough preparation has been done to effectively combat the threat of terrorism with chemical weapons.

“There is a wide range of elements that need to be put in place to protect effectively against chemical agents,” he said. He added that authorities in the UK should invest in precautions such as detectors and software which would allow them to manage an attack as it unfolded, by identifying the area under threat and evacuating areas without sending them through the hazardous area.

“Basically, it is similar to the installation of fire alarms. Even with these alarms in place there is still a risk that people will die in fires, but their installation does allow us to protect as many people as we can. And that is exactly what we are trying to do. Protect as many people as possible.”

Dr Bennett, the security expert specialising in aviation, said he would encourage the government to spend their funds on the intelligence and security services. “The best defence is a well funded intelligence service,” he said. “Prevention is much more effective; it is much safer than cure or even mitigation.”