Terrible legacy will last for years


Last updated at 17:57 12 December 2005

The initial official assurances that the black cloud belching out of the Buncefield fuel depot is not toxic should be taken with a large pinch of chemically contaminated salt.

Nobody yet knows exactly what the smoke contains, but it is clear there is an immediate threat to asthmatics and others with respiratory problems - and that over the long term it poses a cancer hazard.

The perils arise because the fierce fires are actually burning the fuel inefficiently, causing dangerous pollutants to go, literally, up in the smoke.

Much of the problem is caused by the dense soot which makes the cloud black. The soot particles - coated with toxic metals and chemicals - attack the respiratory system, and hospitals across the South-East are bracing themselves for an influx of patients with asthma attacks.

Professor Warren Lenney of the British Lung Federation - himself a consultant at the University Hospital of North Staffordshire - says: "You breathe them in, get irritation and start coughing.

"The irritation can cause swelling of the throat and upper airways, and if the swelling carries on you will have difficulty breathing."

The longer term cancer threat is, if anything, even more worrying. It comes from Polycyclic Aromatic Hydrocarbons, such as benzene and pyrene, also emitted by incomplete combustion.

When breathed in, they cause chemical changes in the body, releasing free radicals that can cause cancer. The disease takes a long time to take effect, so it will be decades before the full toll of the disaster is known.

Geoff Charlton of the consultancy Disaster Advice says of the cloud: "We know it's toxic. If you went anywhere near it and started to breathe in, it's probably the same as smoking 400 cigarettes."

Weather threat

The key factor is the weather. The accident took place on a still, clear, cold and frosty morning with a "temperature inversion".

Whereas the air normally gets colder the higher you go in the atmosphere, an inversion causes cold air to be trapped near the ground by a warmer layer above it.

This acts like a cap, trapping the cold air and preventing the pollution it contains rising harmlessly up in the sky. So it stays near to the ground where people can breathe it.

The same effect ensured the sound the explosion spread outwards rather than upwards, causing it to be heard widely over South-East England.

The lack of wind makes things even worse. Instead of being blown away, the pollution has been able to slowly diffuse over a wider and wider area.

The official Environment Agency expects that, unless conditions change, it will eventually spread over most of South-East England, and even cross the Channel.

The Met Office said rain could cause another hazard, by turning the cloud into a black rain that could contaminate farmland and affect people.

Forecaster Peter Kidds said: "This is going to affect grazing animals because the grass could be contaminated. It might stop milk from the South-East of England being usable. It will make people dirty and those with respiratory problems are likely to suffer."

As if this was not enough, there is yet another danger - that fire fighting efforts could cause even more pollution.

The Environment Agency fears that using water or foam to try to douse the flames could flush poisonous chemicals into rivers and streams, and perhaps even contaminate water supplies.

There is, however, one saving grace. Britain has 11,000 officially designated 'major hazards' such as the Buncefield depot, where an accident could seriously endanger people and the environment beyond the plant's boundaries.

Yet the explosion, though massive, is only the fourth really big one in Britain in more than 30 years. The 1974 Flixborough disaster was followed by blasts at a refinery at Milford Haven, South Wales, in 1994 and at a Humberside refinery in 2001.

The Flixborough catastrophe caused a major overhaul of safety regulations which has helped ensure there have been so few repetitions. Official government bodies, including the Environment Agency and the Health and Safety Executive, are already preparing their investigations into the blast.

It is vital that they uncompromisingly work out what went wrong, and that ministers do not shirk from imposing any necessary tightening of safety rules and controls to ensure that such explosions - and the polluting clouds that they can release - remain extremely rare.

It is fashionable to decry regulation, and there is indeed no sense in preserving rules that burden business and ordinary people, while bringing them no benefit.

But, at times like these, we should also remember that good laws and regulations protect the public - and that they should be cherished for doing so.

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