Bombs were dropped on the town of Khan Sheikhoun, suffocating victims in their sleep. People are seen spraying victims, trying to remove the gas from their clothes and bodies

Hundreds were left injured in the wake of the attack on the rebel town of Khan Sheikhoun in north eastern Syria.

The atrocity prompted international condemnation of President Bashar al-Assad’s regime, with world leaders quick to point the finger at the dictator’s regime.

Sarin gas is a highly toxic, lethal nerve agent, even in the smallest of doses – and even more deadly for children.

The man-made nerve agent, was originally made as an insecticide, in Germany in 1938.

It is clear, colourless and has no taste or odour in its pure form.

It belongs to a group of chemicals called organophosphates, and is extremely poisonous.

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Professor Rod Flower, emeritus professor of pharmacology at Queen Mary University of London and fellow of the Royal Society, told The Sun Online, the agent is “very volatile”, making it a highly dangerous.

“If you leave it around in a room it will evaporate very quickly,” he said.
“That’s why its so easy to use as a chemical weapon, because it evaporates quickly.

“It is extremely poisonous if you breathe it in. Victims will become very ill, very quickly, within minutes, literally just a couple of breaths.”

In the last series of the Channel 4 show Homeland, character Peter Quinn was exposed to sarin nerve gas, and shown to foam at the mouth

Witnesses described seeing victims of yesterday’s attack foaming at the mouth and suffering fits.

Hussain Kayal, 26, one of the first on the scene, told The Times: “I felt intense pain in my throat as it started to close.

“I felt paralysed.

“Inside the houses we found sleeping families choking.

“They were having seizures.

“Their noses were full of foam and their eyes were half closed.

It is extremely poisonous if you breathe it in. Victims will become very ill, very quickly, within minutes, literally just a couple of breaths

Professor Rod FlowerFellow of The Royal Society

“People were suffocating in front of our eyes.”

Sarin gas interferes with the nervous system, Prof Flower explained.

The job of the nervous system is to pass messages from the brain to other parts of the body – telling it what to do.

In order for those chemical messages to reach different parts of the body, they have jump from one nerve to another, across a gap.

Sarin nerve gas interferes with those chemical messages, in such a way that just a short exposure will stop the messages being transmitted properly.

THE IMMEDIATE SIGNS A PERSON HAS BEEN EXPOSED TO SARIN GAS

Sarin is a clear and colourless gas, so people may not know they have been exposed.

Those exposed to a low or medium dose of sarin gas by breathing contaminated air, eating contaminated food, drinking contaminated water or touching a contaminated surface may experience symptoms within seconds, according to the Centers for disease Control and Prevention in the US (CDC).

In others it may take hours for symptoms to appear.

hose who have been exposed may experience:

runny nose

watery eyes

small pupils

eye pain

blurred vision

drooling and excessive sweating

a cough

tightness in the chest

rapid breathing

diarrhoea

nausea and vomiting

weeing more often

confusion

drowsiness

weakness

headache

slow or fast heart rate

low or high blood pressure

Exposure to larger amounts of the nerve agent can have much more harmful, if not fatal, effects.

People may experience:

loss of consciousness

convulsions

paralysis

respiratory failure leading to death

Prof Flower described it as being like a light switch being permanently “on”.

“It’s like a continuous stimulation of the nerves,” he said.

“Ultimately death is caused by asphyxia, as the muscles used for breathing become paralysed.

“But, before that, it causes nasty symptoms.”

The first sign is typically drooling uncontrollably at the mouth, Prof Flower explained.

Then, as some images from yesterday’s attack reveal, victims will often then foam around from the mouth.

“This is very, very common,” he said.

“What happens is the nerves get jammed in the position of continuous stimulation in the salivary glands, and the mucus glands, causing a runny nose.