BRITAIN: Fears that a cloud of toxic smoke from the blaze at the Hertfordshire oil depot could descend on southeast England, blanketing London and countryside from Wiltshire to Kent appeared to temporarily recede yesterday thanks to a combination of high air pressure and the fire fighting effort on the ground.
Air quality control experts monitoring the 200-mile wide cloud, which has now spread as far as northern France, said the unusual weather conditions had trapped oily discharges from the inferno at the Buncefield depot at 10,000ft.
Although "moderate" pollution had been recorded in four locations in southeast England so far there was no sign of ground contamination.
However, with winds expected to pick up last night there was a risk that thousands of tonnes of oily particles could start falling to earth tomorrow
The changing weather could also bring to ground gases containing nitrogen-oxide and other noxious chemicals, threatening people with asthma and other respiratory ailments.
"We have been very lucky so far," said John Bower of Netcen, the research group that runs the UK's national air-quality monitoring network.
"The levels of pollution at ground level are not showing anything unusual at the moment."
With the cloud now extending across the channel to Normandy, Brittany and heading towards Spain, ERM, the world's largest environmental consultancy, said it was imperative that the blaze should be extinguished as soon as possible.
Firefighters, aided by oil industry specialists, battled yesterday to smother the fires on the 100-acre site at Hemel Hempstead. And while by lunchtime the crews had succeeded in extinguishing the flames in 10 of the 20 tanks, the operation had to be suspended shortly after 3pm when one of the tanks that had previously been doused with foam reignited, threatening to exploded an unknown chemical in a tank nearby.
Ordering all 150 fire fighters to withdraw from the scene, Hertfordshire's chief fire officer Roy Wilsher said: "The last thing we want is a human tragedy."
Last night the London Meteorological Office (Met Office) forecast no rain - which would force the pollution to ground level - for at least 36 hours.
A weak weather front is expected to move in from the north today which will blow the cloud to the south. However the plume of pollution is expected to remain at 10,000ft or above.
"It is moving at about 40mph, and dispersing as it moves away from the source. Satellite images show it becoming diffuse," said Wayne Elliott of the Met Office.
According to ERM if, as is feared, the fires are still raging tomorrow, the risk of exposure to smoke in and around Hemel Hempstead could increase because of the expected change in the weather.
"Stopping the fire as soon as possible is, therefore, an important task," a spokesman for the agency said.