On the evening of September 8, 2025, a security incident saw a partial shutdown at Heathrow Airport’s Terminal 4 facility.
It has now been revealed that a suspected tear gas or pepper spray canister triggered a partial evacuation.
The incident, which occurred around 4:56 PM BST, prompted a swift response from emergency services and led to the arrest of a 57-year-old man the following day.
Heathrow Terminal 4 Incident
The incident began in the check-in area of Terminal 4, a busy hub for international travellers. At approximately 4:56 PM, authorities received reports of a potential hazardous materials incident.
Hundreds of passengers were quickly evacuated from the landside check-in zone as a precaution. The Metropolitan Police, London Fire Brigade, and London Ambulance Service descended on the scene to investigate.
Initial tests found no elevated levels of hazardous substances, but the situation escalated when a canister, believed to contain CS spray (a type of tear gas used by UK police), was discovered.
CS spray, classified as a firearm under UK law, causes temporary irritation to the eyes, skin, and respiratory system. Around 20 to 21 people reported symptoms like stinging eyes and skin discomfort, though no serious injuries were recorded.
Paramedics treated affected individuals on-site, and the incident was initially described as causing “mass hysteria” among some passengers, amplifying the disruption.
The check-in area remained closed for about three hours, reopening around 8:00 PM.
The Arrest and Investigation
On September 9, 2025, police arrested a 57-year-old man in connection with the incident. He faces charges of possession of a firearm (due to the CS spray canister) and causing a public nuisance.
As of September 10, 2025, he remains in custody while investigations continue.
Authorities have confirmed the incident is not terrorism-related, easing concerns about broader security threats. No further details about the suspect’s identity or motives have been released.
Impact on Passengers and Airport Operations
Despite the evacuation, Heathrow officials reported minimal disruption to flight schedules. Most departures and arrivals from Terminal 4 proceeded as planned, according to flight data.
However, the temporary closure of the check-in area caused inconvenience for passengers, many of whom were caught off guard by the sudden evacuation.
Heathrow Airport issued a public apology, emphasizing their commitment to passenger safety and thanking travellers for their patience.
Conclusion
This incident highlights the challenges of maintaining security in high-traffic environments like Heathrow, which serves millions of passengers annually.
CS spray, while non-lethal, can cause significant distress in confined spaces, as seen in this case. The swift response from emergency services underscores the importance of preparedness in handling unexpected threats, even those not linked to terrorism.
As investigations continue, authorities are working to determine how the canister entered the airport and what prompted its use.
Heathrow Airport Terminal 4 has now restored normal operations.