05/12/2012 06:52 GMT | Updated 03/02/2013 05:12 GMT

Halabja and the Dangers of Mustard Gas

On 16 March 1988, Saddam Hussein's regime dropped bombs containing various poisonous chemicals, including mustard gas, on the Kurdish town of Halabja, killing some 3000 to 5000 people. Even more people were wounded.

On Monday, 3 December, BBC world affairs editor John Simpson reported on the continuing legacy of the attack on the town and its residents. In his report, shown on the BBC News at Ten, he interviewed Nasrin Abdul Qadir who had lost 17 of her relatives, including her mother, her two brothers, and her sister in the attack. Simpson then entered the cellar of the family house where they had been gassed.

"Even 25 years later, the stench of mustard gas is still strong" observed BBC Simpson while standing in the cellar. The gas "makes our eyes weep and our heads ache," he said, before making a hasty exit. The report noted that not only cats, rats and other animals who had found their way into these contaminated cellars had died but also people who had entered them recently had died.

Mustard gas is actually not a gas but a thick viscous liquid that can remain on the ground for years when conditions are right. The chemical releases a vapour that is either odourless or smells of mustard depending on the purity of the liquid.

What struck me about Simpson's report was that he did not have a gas mask and was not wearing any form of protective clothing. As he could smell the gas, it seemed to me at first that he was putting himself and the cameraman at some considerable risk. They were either being very brave or foolhardy.

Mustard gas was first synthesized in various ways from chlorine- and sulfur-containing compounds by French, British and German chemists during the latter half ot he 19th century. It was introduced as a chemical weapon during the First World War when the Germans bombarded British frontlines on the Western Front with some 50,000 mustard shells.

Mustard gas is a most dreadful chemical warfare agent. Depending on the level of exposure, it can cause blistering of the skin, inflammation of the lungs if the vapour is inhaled, loss of eyesight, and internal and external bleeding. Death of victims exposed to high concentrations of the poison can be slow and painful. In World War I soldiers sometimes took four to five weeks to die from the poison and the pain was often so bad they had to be strapped to their beds.

After it was first used in the Great War, Fritz Haber, the German chemist who became known as the father of modern chemical warfare, considered mustard gas to be "a fabulous success." As I mention in my book, Gas! GAS! Quick, boys! How Chemistry Changed the First World War, the chemical became known as the "king of the battle gases." Between July 1917, when it was first used, and the end of the war German mustard gas accounted for around 125,000 British casualties, that is some 70% of all British gas casualties in the war. It should be noted, however, that only 1.5% of the mustard gas casualties proved fatal.

Fortunately for Simpson and the cameraman, they had British chemical warfare expert Hamish de Bretton-Gordon with them. He carried a hand-held chemical agent monitor that can reliably detect even trace concentrations of mustard gas. So, when Simpson and the cameraman entered the cellar, I presume the atmosphere had already been tested and deemed safe. Even so, I would not like to have been in Simpson's shoes.

Michael Freemantle's latest book, Gas! GAS! Quick, boys! How Chemistry Changed the First World War is available to purchase here:

His previous book, An Introduction to Ionic Liquids is available here: