The potential cause of the incident has been explained
A man has been arrested following what emergency services called a “potential hazardous materials incident” at Heathrow Airport.
The check-in area at Terminal 4 was cleared on Monday after about 20 people reported feeling unwell.
Specialist officers, along with crews from the London Fire Brigade and London Ambulance Service, carried out a detailed search of the site.
During the search, Metropolitan Police officers discovered a canister believed to contain CS spray. Police said the substance is thought to have triggered reactions among people inside the airport.
A 57-year-old man was arrested on suspicion of possessing a firearm (CS spray) and causing a public nuisance. He remains in custody, and the incident is not being treated as terrorism-related.
The check-in area inside Terminal 4 was evacuated “as a precaution whilst firefighters conducted operations”, LFB said in a statement. It went on: “Specialist crews were deployed to carry out an assessment of the scene. No elevated levels of hazardous materials were discovered by the brigade.”
A London Ambulance Service spokesperson said a total of 21 patients were treated. One was taken to hospital while the others were discharged at the scene.
A spokesperson for the Metropolitan Police said yesterday: “On Monday September 8 at 4.56pm, police were called to a potential hazardous materials incident at Heathrow airport, Terminal 4.
“Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a thorough search of the area. Around 20 people reported an injury. None were deemed to be life-threatening or life-changing. Inquiries are ongoing.”
At 8.27pm, the airport said on X that emergency services had confirmed the terminal was “safe to reopen” and it was doing “everything we can to ensure flights depart as planned today”.
The LFB said it was in the process of standing down its response, and that the cause of the incident remained under investigation. Earlier on Monday evening, the airport had advised passengers not to travel to Terminal 4, while National Rail Enquiries said trains were unable to call at the terminal because of the incident.
