Four fire engines and around 25 firefighters were called to a fire at a recycling and waste disposal site on Chigwell Road in Woodford Green.
A small area of a garden waste heap at the single-storey recycling site was on fire. There were no reports of any injuries.
The cause of the blaze was accidental. A natural chemical reaction within the garden waste heap generated heat, which in turn caused it to start smouldering.
Site staff separated the heap with a digger to quickly stop the fire spreading while firefighters used water to quell the smouldering.
Sub Officer Andrew Clark, who was at the scene, said: “When we arrived we saw a lot of wispy smoke building up over the compost heap. When the heap was separated by a digger, heavy white smoke came out from inside it.
“Luckily, the compost heap was separated from flammable materials by a high concrete wall, minimising the risk of fire spreading.”
The Brigade was called at 2107 and the fire was under control by 2339. Fire crews from Woodford, Leytonstone, Walthamstow and Chingford fire stations attended the scene.