As always when large quantities of a substance like oil are involved, the depot fire at Buncefield holds the potential to cause environmental damage.
However, there is little sign of any impact so far.
Compared with the oil-well fires which raged in Iraq during its turbulent recent history, the quantities involved at Buncefield are small.
"It's similar, except there's only one location and fires will burn for a
short time," said Professor Ian Colbeck, from Essex University, who worked on the Iraq fires.
"But data measured over large areas of southern England show elevated concentrations of particulate matter - not so high that it can become a serious hazard, but five or six times background levels," he told BBC News.
"If you're susceptible to asthma or respiratory problems the advice would be to stay indoors."
Particulate matter is basically soot, and comes in different sizes; smaller particles are known to be carcinogenic in sufficient quantities, but Professor Colbeck said this is unlikely to be an issue with a one-off fire.
Taking the heat
At Buncefield itself, firefighters are now trying to control the blaze with water and foam. This action may bring problems of its own.
There are different formulations of extinguishing foam available, and some would have an impact on water supplies and wildlife if they escaped from the site in large enough amounts.
Smoke protection is essential for those working close to the blaze
But barriers have been erected to contain the material on site.
"We've got groundwater underlying the site, so there would be a big threat from a long-term issue," said Colin Chiverton, from the Environment Agency.
"With the work we've done and the information we have to date, we're confident that within the site they can contain the waters from putting the fire out, which will protect the watercourses."
Drinking water abstraction boreholes in the Thames Valley have been closed as a precaution, the agency says.
Paradoxically, tackling the blaze could potentially lead to a greater problem with airborne pollution.
Jane Halpin, Director of Public Health for Bedfordshire and Hertfordshire, told BBC News: "As the fire is hopefully brought under control and cools, so the temperature of the smoke rising cools, and the plume starts to fall to Earth."
So a greater proportion of the smoke could be nearer to the ground, potentially leading to an upsurge in respiratory problems.
So far there appears to have been no rise in the number of people seeking treatment from their GPs.
Burning oil principally produces carbon dioxide, a greenhouse gas.
But the quantities involved are far too small to have any meaningful impact on climate change.
Ian Colbeck believes we will see some particulate matter, which the smoke clouds also carry, coming down to earth.
"As it rains today, you will get a lot of the particles washed out," he said.
These particles will fall on land or water and could be picked up by livestock, fish or other animals.
Where it falls will depend partly on atmospheric conditions and partly on how quickly firefighters extinguish the blaze.
In assessing Buncefield's overall environmental impact, it is worth bearing in mind that an established method of dealing with oil spills is to burn them off, as oil in liquid form causes far more damage than when it is burned.