Police were called to a potential hazardous materials incident at Heathrow Airport, Terminal Four, just before 5pm yesterday.

Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a thorough search of the area.

Following the search, Met officers located a cannister of what is believed to be CS spray.

It is thought that this substance caused a reaction to those within the airport.

Around 20 people reported to paramedics after the (believed) CS spray caused irritation. It has been confirmed that the spray did not cause any life-changing/threatening injuries.

Following urgent enquiries, a 57-year-old man was arrested on suspicion of possession of a firearm (CS spray) and causing a public nuisance.

He remains in police custody.

The incident is not being treated as terrorism related.

The investigation remains on-going.

A London Fire Brigade spokesperson said: “Firefighters responded to a possible hazardous materials incident at Heathrow Airport yesterday.

“The Brigade was informed that several people were reporting a variety of minor symptoms, which could indicate exposure to a chemical or another type of substance. As is routine for these types of incidents, specialist crews were deployed to carry out an assessment of the scene. We can confirm no elevated levels of hazardous materials were discovered by the Brigade and the area was declared safe.

“Terminal 4 check-in was evacuated as a precaution whilst firefighters conducted operations. Around 20 people were assessed on scene by paramedics from the London Ambulance Service, with one person taken to hospital as a precaution.

“The Brigade was first called about the incident at 1701 hrs, with crews from Feltham, Heathrow, Wembley and surrounding fire stations mobilised to the scene. The Brigade was stood down by 1926 hrs.”

A London Ambulance Service spokesperson said:

“We were called at 4.50pm today (Monday 8) to reports of an incident in Terminal 4 at Heathrow airport.
“We sent resources to the scene including ambulance crews, our cycle response unit, an incident response officer, an advanced paramedic practitioner and members of our hazardous area response team (HART).

“We treated 21 patients before taking one to hospital. All of the others were discharged at the scene.”