August 27, 2021

expert reaction to Leamington Spa fire

There have been several reports of a large fire in an industrial state in Leamington Spa, thought to involve a building belonging to Leeson Polyurethanes Ltd.

Prof Clifford Jones, Visiting Professor, University of Chester, said:

“The abundance of smoke evident in the photograph of the fire on the BBC web pages suggests that the fire is propagating by smouldering, not by the more powerful flaming.  One would intuitively expect  such a material to   burn that way and possible consequences  include the following.   

“A smouldering-to-flaming transition occurs when a smouldering fire receives an augmented oxygen supply, perhaps because of deliberate breakage of a door in firefighting. The smoke itself being laden with flammable breakdown products can explode.  

“The smell  reported I attribute to the breakdown products.”

Dr Claire Ryder, an atmospheric scientist at the University of Reading, said:

“Current weather, dominated by a high pressure system over the UK, light winds and lack of rain, mean that the smoke will be dispersed more slowly than it would if it was windy or rainy. This is exacerbated by the lingering, low concentrations of wildfire smoke higher up in the atmosphere over the UK, which have been transported by weather systems from North American wildfires.

“Smoke can contain hazardous particles of tiny sizes which can penetrate into the lungs and cause respiratory problems. The exact impact depends on their size and chemical composition. It would be advisable to stay away from the smoke altogether, or if not possible then keep windows and doors shut, and wear a mask outside to help filter out microscopic airborne particles which may linger in the air.”

Mr Tony Ennis, Director of HAZTECH Consultants Ltd, said:

“Polyurethanes are a very common group of polymers made from combinations of various alcohols and isocyanates. When exposed to heat, Polyurethanes typically start to decompose at approximately 280°C with the decomposition products dependent on temperature. Note that fire temperatures may reach over 800°C.

“Polyurethane fires can generate cyanide gas as a by-product of combustion plus carbon monoxide (also toxic) and a number of other potentially toxic substances including acetonitrile, acrylonitrile, pyridine, and benzonitrile and carbon soot due to incomplete combustion. The combination of materials produced will be dependent on both the type of polyurethane and the temperature. In addition to combustion by-products, the heat will cause thermal decomposition into various other materials including ammonia, benzene, toluene and other aromatic ring molecules.

“The combination of toxins in the smoke plume may cause distress, particularly to anyone who has existing lung or breathing complaints.

“Decomposition produces a dense yellow smoke, and combustion a dense black smoke containing sooty particles as well as various organic materials. Many of the decomposition products are heavier than air and will fall to ground when the plume cools.

“The best advice is to stay indoors and close all doors and windows securely until the smoke abates. This will minimise exposure to the toxins in the plume.”

Declared interests

None received.