What is a chemical weapon? Have they been used in Ukraine and when have they been used before?

ITV News Correspondent Peter Smith reports on the allegation of a chemical attack in Mariupol

Words by ITV News Content Producer Amani Hughes

An investigation is underway to establish whether chemical weapons were used in Mariupol by Russian forces, as the UK warned "all options were on the table" if the use of chemical agents was verified.

Here ITV News examines what exactly is a chemical weapon, what effect they have on the human body and where they have been used before.

• What is a chemical weapon?

A chemical weapon is a chemical used to cause intentional death or harm through its toxic properties, according to the Organisation for the Prohibition of Chemical Weapons (OPCW).

Under the Chemicals Weapons Convention (CWC), which was adopted in 1992 and prohibits the development, production and stockpiling of chemical weapons, a chemical weapon can fall under three categories.

Toxic chemicals and their precursors

Any chemical which, through its chemical action on life processes, can cause death, temporary incapacitation or permanent harm to humans or animals. This includes all chemicals, regardless of whether they are produced in facilities or munitions or elsewhere.

Precursors are chemicals that are used for the production of toxic chemicals.

Munitions or devices

Any munitions or devices specifically designed to inflict harm or cause death through the release of toxic chemicals.

Among these could be mortars, artillery shells, missiles, bombs, mines or spray tanks.

Equipment ‘directly in connection’ with munitions and devices

Any equipment specifically designed for use ‘directly in connection’ with the employment of the munitions and devices identified as chemical weapons.

• What happens to a human body when chemical weapons are used?

Chemical agents are chemical weapons that take the form of gases, liquids, or solids that can poison people, animals and plants and can cause injuries and death.

There are various types of chemical agents that affect the body in different ways:

• Choking agents

• Blister agents

• Blood agents

• Nerve agents

• Riot control agents.

Examples of agents include chlorine and phosgene which are choking agents, they irritate the nose, throat and especially the lungs. They work by causing a build-up of fluid in the lungs, which leads to suffocation.

Sulfur mustard (mustard gas) is a blister agent, they cause the skin to become red and irritated; large amounts will make the skin blister which resembles severe burns and often results in blindness and permanent damage to the respiratory system.

Blood agents such as hydrogen cyanide and cyanogen chloride inhibit the ability of cells to use oxygen, effectively causing the body to suffocate – which leads to damage of vital organs.

Sarin is a type of nerve agent which is highly toxic with rapid effects. A small dose of a nerve agent can dim or blur vision, cause eye pain, runny nose and a shortness of breath, and a large dose can cause interruption of breathing, muscle weakness, loss of consciousness, convulsions and death.

The last category – riot control agents – have short term effects and can cause irritation to the eyes, mouth, throat, lungs and skin. Examples include tear gas and pepper spray.

White phosphorus is not a chemical weapon as defined under the CWC, it is a chemical agent and is toxic, but it is not governed by the CWC.

• Have they been used in Ukraine?

Western officials are examining claims that a chemical agent was used by Russian forces in a drone attack on the besieged city of Mariupol.

The claim was made by the Azoz regiment, a far-right group now part of the Ukrainian military, but it could not be independently verified.

The Kyiv Independent news website reported that Azov leader Andriy Biletsky said that three people have clear signs of chemical poisoning and that soldiers were left dizzy and unable to breathe.

ITV News spoke to an Azov volunteer still fighting Russian forces at the Azovstal Iron and Steel Works - the base of the Azov regiment.

Illia Samoilenko said: "The enemy dropped the canisters with some kind of aerosol chemical. It was like a cloud of fog or something like a cloud of smoke."

He said people were having difficulty breathing and people were fainting.

"I may assume that Russians can use it again because they hate us so much. We are still standing. We will stand until we have weapons in our arms and until we are breathing," he added.

'It was like a cloud of fog or like a cloud of smoke'

A victim of the alleged chemical attack said: "I could hardly breathe and immediately felt dizzy, my legs gave way."

A Russia-allied separatist official, Eduard Basurin, appeared to urge the use of chemical weapons on Monday, telling Russian state TV that separatist forces should seize a giant metals plant in Mariupol from Ukrainian forces by first blocking all the exits out of the factory.

“And then we’ll use chemical troops to smoke them out of there,” he said.

• What has the UK and US said in response?

Foreign Secretary Liz Truss said the UK was “working urgently” to investigate the report of chemical weapons being used in Ukraine.

Armed forces minister James Heappey said the use of chemical weapons was “beyond the pale” and if the reports were accurate there would be a response from the UK and its allies.

“It’s important to recognise that there are all sorts of ways in which these things could be used, from the use of tear gas which is effectively a riot-control measure, all the way through to utterly devastating lethal chemical weapons systems, so I don’t think it’s helpful to be too binary about the situation because these are highly nuanced,” he told Sky News.

But he added “there are some things that are beyond the pale and the use of chemical weapons will get a response, and all options are on the table for what that response could be”.

Pentagon spokesman John Kirby said in a statement that the US could not confirm the drone report coming out of Mariupol, but he noted the administration’s persistent concerns “about Russia’s potential to use a variety of riot control agents, including tear gas mixed with chemical agents, in Ukraine.”

• How will a chemical weapon attack be confirmed?

Hamish de Bretton-Gordon, former UK and NATO commander of chemical and biological defence forces, told ITV News that doctors will be taking medical samples and environmental samples to be tested to define if it was a chemical attack or some sort of accident.

He said: “To establish that this was a chemical attack, we need the evidence and there will be doctors and others on the ground collecting evidence at the moment, environmental evidence, soil samples in the area, but most importantly, medical evidence from the casualties.

“Those samples will then need to be smuggled out of Mariupol to laboratories, ideally to the Organisation for the Prohibition of Chemical Weapons (OPCW) so they can be analysed and they should be able to tell for certain whether this was a chemical attack, a toxic accident or a false flag operation.”

“It’s very important that we work out exactly what happened in Mariupol, because NATO, the UK and the US government have said and reiterated again they will act if it is a chemical attack,” Mr de Bretton-Gordon added.

“We know from Syria that the UK, the US and France struck key Syrian targets after they used chemical weapons, and the inference might well be that similar would happen, or certainly we would give the intelligence and capability to the Ukrainian government to attack those Russian forces, that might be responsible if this is a chemical attack.”

• Where have they been used before?

The most notable uses of chemical weapons were in the Iran-Iraq War of the 1980s and the Syrian Civil War.

The Halabja massacre took place or Halabja chemical attack took place on 16 March 1988 against the Kurdish people of Iraq. The UN confirmed that mustard gas was used in the attack, along with unidentified nerve agents.

As many as 5,000 people died when the deadly gas was released on the northern town by Saddam Hussein’s forces.

There have been numerous reports of chemical weapons being used in the Syrian Civil War by Bashar al-Assad’s regime.

One of the worst attacks was in Ghouta in August 2013 when the nerve agent Sarin was used. It killed more than 1,400 Syrians, many of them children, the US state department said.

The symptoms of those affected was body convulsion, foaming from mouths, blurry vision and suffocation.

In March 2018 the UK accused Russia of using the Novichok nerve agent to assassinate a former Sergei Skripal, and his daughter, Yulia, in Salisbury.