A dark cloud of smoke descended upon Enfield following the massive oil depot fire in Hertfordshire.

Residents were amazed to see the black pall appear in the north of the borough from 11.30am on Sunday, eventually reaching ground level in neighbouring Haringey at 6pm.

Nikki Walsh, 35, who lives near Trent Park, said: "We had a very clear view of the cloud coming over Trent Park. It suddenly went dark and I thought it was going to snow it was like a scene from The War of the Worlds."

The 6am explosion at the Buncefield depot, in Hemel Hempstead, 21-miles from Enfield, sparked the largest fire in peacetime Europe, sending flames up to 200ft into the air. The sound of the explosion could be heard within a 100-mile radius of the blast.

Yesterday afternoon, firefighters from across the south east, including Enfield, were still battling to bring the blaze under control. Two people were seriously injured in the blasts.

Enfield residents were worried pollutants from the smoke plume would drop to the ground and pose a health risk. "We were concerned about the horses because we could smell the cloud," added Ms Walsh.

Air quality analysts at King's College recorded moderate levels of pollution they believe to be from the cloud at their recording station at Tottenham Town Hall.

Tim Baker, a senior air quality researcher, said his team detected a measure of fine particles in the air, known as PM10, linked to respiratory problems.

But he said: "It was only a minor rise. The levels we did see were no higher than a normal pollution event like a heatwave during the summer or Bonfire Night."

Professor Stephen Spiro, of the British Lung Foundation, added: "We anticipate there will be little lasting damage to the lungs of those exposed to the smoke."