With the use of sarin in Syria being a frequent topic of debate I've approached a number of chemical weapon specialists with a set of questions on sarin, and the alleged attacks in Saraqeb and Khan al-Assal to help shed some light on the topic, and hopefully clear up some confusion.

Sarin

How is Sarin typically weaponised?





Sarin is a lethal war agent. It is designed and produced to cause death in humans. It is usually loaded into a carrier projectile which is designed to contain liquid agents. Sarin can also be dispersed by other means such as aerosols.





If projectile delivered, an explosive burster charge is used to open the projectile and disperse the Sarin without destroying all of it.





What form does Sarin take? Can it be liquid, gas, powder, etc? Does it have a particular smell or colour?





In its weaponised state Sarin is a colourless and odourless liquid and is dispersed either in that form or as a vapour. That is not to say that a Sarin producer could not add ingredients to make it detectable either by sight or smell although this would require careful research to ensure that the precursors and additives did not interfere with each other. It would be an unusual thing to do.





It would not be viable from an effectiveness standpoint to use powdered Sarin, just as it is not possible to have powdered water. Sarin is volatile and able to disperse efficiently by being mixed with Isopropyl alcohol so that it can turn into a vapour and move with air currents and then either be inhaled by living organisms or through absorption. If it was turned into a solid (powder) then it would be too heavy to be dispersed in an efficient manner.





Have you ever heard of Sarin being used in a diluted form, or mixed with other chemical substances to make it less lethal?





No. The advantage of CW is that they are cheap, easy to disperse and able to kill/injure a large amount of people. The ratio between dead and injured will depend on the agent concentration and exposure, in what environment (indoors/outdoors) and in what atmospheric conditions (wind/ /temperature).





There would be little advantage of making Sarin less lethal because it would still be lethal in the right conditions. If the objective of an attacker was to temporarily incapacitate an enemy then other CW would be considered such as mustard agents, then the attacker would be expected to physically enter that area to control it otherwise the attack would serve no purpose militarily. In this scenario, the attacker’s soldiers/vehicles would be equipped with protective equipment/clothing otherwise they would be liable to be contaminated too.





Other agents, such as CS would be far more effective at causing non-lethal effects with the intention of temporarily incapacitating people and encouraging them to leave an area of their own accord. ‘Mild’ nerve agent poisoning will mean that people will be more likely to stay in the area.





A number of reports have claimed to have proven the use of Sarin through tests on hair, clothing, blood, tissue, and urine samples. How would these be tested for the presence of Sarin?





I would expect that each item would be analysed with the correct equipment which has been properly maintained and calibrated after each item has been analysed, otherwise one item could contaminate the rest of the tests, resulting in a higher cumulative result. I explained in my Q&As with Alfred Hackensberg that there would be a requirement for tests to be taken of the environment and from local people who had not been killed or injured in the attack to compare blood samples. To be digested and turned into urine, the victim would have had to have consumed such a small amount in another liquid that it would not have killed them. If they had been killed by drinking Sarin, it would not have entered the digestive system.





But anyway, to answer the question, all the items would be tested for traces of the lethal precursors of Sarin and in the case of the blood, the evidence of asphyxia, the method by which Sarin will ultimately kill its victim.

If Sarin was detected in hair and urine wouldn't that suggest small, non-lethal quantities, being ingested over a period of time?





Yes. If someone was killed from Sarin CW attack then the Sarin would not be digested or grown out into someone’s hair. If they had been attacked and survived in the past, they would have told someone about it, there would have been more witnesses and it is possible that the attack would have left permanent indicators of its presence, such as in the hair of the survivor.





If Sarin was on clothing how hazardous would it be to handle that clothing without correct protection?





If recently contaminated and not subjected to any decontamination procedures, then there would be a contamination risk, especially in confined spaces. Individual protective clothing (IPE), respirator with correct filter would be required to be worn by everyone coming into contact with it.





Is it possible other substances could produce false positives for Sarin?





Yes it is. Most chemical agents are detected in the field using generic technologies. Precise field detection is possible through reagent kits but this requires training to use accurately. As an example of detecting a false positive, insect repellents work in much the same was as nerve agent by attacking the nervous system of the insects and even in small quantities, they will cause electronic portable detector systems to alarm. The quantities of active agent in insect spray are diluted so that they won’t harm humans for normal use, although it is likely that it will be ingested by people who use such substances on a regular basis.





After a suspected Sarin attack how should the victims be processed, and what precautions should be taken?





This very much depends on who is suspected of being a CW victim (military or civilian) and what infrastructure (qualified medical staff, suitable vehicles, and suitable accommodation) is in place to deal with CW attacks. The more resources applied, the more costly but effective the process.





Nations have their own procedures, but some basic principles need to be adhered to; minimising further contamination, transferring CW victims into vehicles and then to a hospital will ensure that the vehicles can no longer be used until decontaminated and the people in the hospital who were not CW victims would become at risk of contamination. It is possible to have sealed wards but it would be difficult to obtain video footage from inside the contaminated area as there would need to be a comprehensive system of decontamination for anyone leaving. All the staff would need to wear IPE and be cognisant of symptoms, decontamination drills and procedures.





The most efficient method of delivering aid to CW victims would be to bring the suitably trained medical staff to the victims so that they can be treated and processed, decontaminated and then transferred to an aid post or hospital.





Setting up a hot line and cold line upwind of the incident is the normal process for chemical incidents controlling access and egress to/from the hazardous area with detection, decontamination and casualty handling incorporated into the mitigation process.





The corpses of CW victims would likely be burned to avoid further contamination of the ground, other people or buildings.





If these precautions are not taken what is likely to happen to the people coming in contact with the victims?





A person with contaminated clothing is further dispersing the agent. Anyone coming into contact with a contaminated person will be at risk of becoming contaminated themselves, especially in confined areas such as in buildings or vehicles.





How long would it take Sarin to become harmless, or dissipate? In general terms are we talking minutes, hours, weeks?





This is difficult to answer because of the variables that could exist but Sarin is a non-persistent and highly volatile liquid which disperses and vaporises rapidly dependent on conditions of temperature and air flow. A single projectile of Sarin fired in a hot, sunny featureless environment during a windy day could feasibly take minutes to dissipate. At the other end of the spectrum, a sustained bombardment/barrage in an urban area during a period of no wind and no sustained periods of sun would be more likely to create a scenario where pockets of exposed Sarin would last for days, unexposed Sarin could last for weeks and CW UXO could remain in the area for years.





Sarin is a non-persistent agent which means that the entity who used it is intending to enter the contaminated area soon after the attack when safe to do so. IPE and detection equipment would be used by first-in elements and until the all-clear was given.





Saraqeb





The Saraqeb attack is probably one of the mostly well documented alleged chemical weapon attacks of the conflict. Canisters inside containers filled with white-grey powder were reportedly dropped from a helicopter, landing in two locations, one near a road, where no victims were reported, and the other in the courtyard of a family home. It was reported that immediately after impact, one of the residents entered the courtyard, and collapsed shortly afterwards, later dying. Shortly after the first victim entered the courtyard more members of the family entered, and also fell ill, as did people responding to the attack. Between 11 to 13 people were reportedly effected, with only one death reported. Video from the road-side location filmed some time after the attack would show children playing near to the remaining white-grey powder with no ill effects reported. (A more detailed breakdown can be found here





Would the above scenario match what you'd expect to see if Sarin has been used in the attack?





Not really. I would be very surprised if a lethal war agent would be dispersed in this way; the risk of contamination to the helicopter and crew would be high. Sarin is not known to be dispersed in a powdered form.





In common with many alleged chemical attacks in Syria the medical staff appears to have no protective gear. If this was a Sarin attack, how likely would it be that the medical staff would be effected, and how long would it take for the medical staff to become effected?





Depending on concentration and method of contact, the medical staff could feel the effects of the agent as soon as they came into contact with the victim or other contaminated articles.





One video shows a car pulling up with at least one victim inside. If this was a Sarin attack, how likely would it be that the inside of the vehicle would be contaminated by Sarin? If the victim inside the vehicle had been exposed to Sarin is it likely other passengers in the vehicle would fall ill?





The inside of the vehicle would likely be contaminated by Sarin if the victim has been in contact with the agent droplets or vapour. The victim would have contaminated skin and clothing which would continue to produce Sarin vapour. The inside of a vehicle is confined and this would mean that everyone in the vehicle would breathe in the Sarin. Contaminated surfaces inside the vehicle could affect future users of the car.





Some people have proposed a scenario where a diluted mixture of Sarin and other substances was used in the attack. If that was the case, would your answers to the above questions change significantly?





I don’t understand why a diluted Sarin agent would be produced or used. If a less lethal agent was required then there are more efficient solutions.





The canisters recovered from the scene of the attacks matched canisters also recovered from an attack reported in Sheikh Maqsoud in Aleppo, where there were again claims of them being dropped from a helicopter, with photographs showing the canister remains covered in white-grey powder.

The same design of canister has also been filmed in a cache of weapons reportedly captured by the Syrian opposition from the Syrian military, and a journalist in Syria has shown the image of the canister to various armed group, many of which have claimed to have seen them in the possession of opposition fighters, claiming to have captured them from the Syrian army.

Another type of grenade, using an identical fuze, was also photographed in Syria , with the photographer being told it was a normal smoke grenade.

There's video footage from the Saraqeb attack showing what's claimed to be the canisters falling through the sky, appearing to produce smoke or a white gas, as well as producing light. The canisters appeared to show signs of heat damage around holes along the body of the canister.





Considering the various information gathered about these grenades is it likely they would have contained Sarin?





Not really. Hand grenades have been manufactured for military use containing lethal war agents in the past. Sarin filled grenades would not include a pyrotechnic burning reaction to generate the toxic smoke as this is not deemed viable or known for dispersal of a Sarin payload.





Is it possible they could have contained another substance that could have caused symptoms seen in the victims of the attack?





It is unlikely that the grenades would have contained a blood, nerve or blister agent. Having seen the footage of the victims, I question whether their symptoms were caused by a CW attack. Without seeing more footage before and after the filming, I’d say that they could have been exposed a number of chemical incidents including toxic smoke inhalation, exposure to industrial chemicals or unintended releases through acts of war.





Could one of those possibly substances produced a false positive for Sarin?





It depends on the chemicals involved. If they were precursors for insect-spray then possibly but it is unlikely that the agent would have been dispersed by means of a grenade from a helicopter.





Is it reasonable that the contents of this grenade could have been emptied and replaced by Sarin?





No. The safe conditions and process required would be the limiting factor as the procedure would be highly dangerous with a high risk of contamination. The gains in filling a small container with a highly volatile lethal agent, which can only be projected over short distances, would seem a risky and unviable proposition.





Khan al-Assal





The Russian government has claimed the Syrian opposition was responsible for the Khan al-Assal attack, with a DIY rocket delivering a payload of Sarin.





What do you think would be involved in putting together a DIY chemical warhead for a DIY rocket?





The rocket would need a viable motor to be able to reach its intended destination. There would need to be a method of breaking or bursting the warhead casing in order for the Sarin to disperse. It is possible to separate the Sarin precursors inside different containers inside the warhead (binary agent) but this further complicates the functioning of the projectile and makes successful use less likely if an improvised system.





The Syrian opposition have the technical know-how to manufacture rockets.





Considering the Russian government's claim that a DIY rocket was used in the attack, what would be the most effective dispersal method once the rocket reached it's target?





Most efficient would be use of a projectile with an air-burst fuze to allow the Sarin to be dispersed above the ground as to contaminate as much of the area as possible. I would also expect that some of these rockets would miss the target wildly, contaminate the wrong targets and in some cases not initiate properly. Simple impact of a thin cased projectile with the ground could be used to disperse the liquid which would then vaporise depending on environmental conditions.





As with the other alleged chemical attacks in Syria the staff treating the wounded appear not to be using any protective clothing. Would this have resulted in medical staff and responders being contaminated if this was a Sarin attack?





Yes. Everyone within a contaminated area would feel the effects of chemical attack, resulting in injury and death. I would be surprised if Sarin victims would be able to be transported to a hospital immediately after an attack without secondary contamination occurring.



