Exposure to concentrated CS gas can lead to blister formation. It is very important to shower as soon as possible.

Egypt is 1 of 5 nations that haven’t signed the Chemical Weapons Convention & are unhindered by restrictions on use of CS gas.

• If you have any information / references about these substances please use the comment section and I will add it to the page. Thank you.

NATO codes of Riot Control Agents (RCAs)

• CS: o-chlorobenzylidene malononitrile
• OC: oleoresin capsicum (OC )
• PS: chloropicrin
• CN: 1-chloroacetophenone
• DM: diphenylaminearsine
• CR: dibenz(b,f)(1,4)oxazepine

Reports from Tahrir Square

CS gas used in Tahrir. The canister reads "Military-type grenade".

Some reports it was CS gas other reports indicate CR gas. I personally witness many victims with their faces covered in white powdery material which seems in line with CS gas (see below). I cannot confirm it was due to tear gas exposure.

Some have indicated tingling sensation, nervous system reactions including seizure like reactions that seems to be relieved by low-dose (3-5mg) diluted diazepam given slowly IV. In the table below OC (pepper spray) does exhibit sensory nervous manifestations. It is important to note that OC is commercially available in concentrations of 1% but is available at much higher concentrations up to 10% as a riot control agent. There are some unconfirmed reports that pepper spray was associated with lethal seizures. Also note that pepper spray responds to decontamination with vegetable oil (see table).

What is probably happening is several types of gas are being used, which makes it confusing.

In terms of treatment some from Tahrir have advised the following:

• Mucogel / epicogel seems harmless enough, is alkaline but I cannot tell what the effects are of rubbing it on the eyes? Especially these antacids contain magnesium and aluminium therefore any acid-base reaction can leave a magnesium or aluminium precipitate which can be harmful to the eye.
• Zantac (ranitidine) is an antacid that works through blocking the H2 receptors. Unlike the antacids mentioned above a solution of Zantac is not alkaline and therefore ineffective when used to neutralize an acid.
• Some have advised water should never be used with certain tear gas. It should always be used when indicated in the table below. You should note that water will increase the symptoms but is essential for decontamination.
• Onions. Reports that onions are effective but I cannot back that with any evidence. The only documentation seems to come from Palestinian activists. One expert attributes its effect to sulfur content, but no confirmation in medical or scientific literature.
• Hydrazine is more concerning since it is toxic. Should never be used.

UPDATE: Human rights officials tell BBC that “military grade” CS gas is being used in Tahrir, not the routine crowd control stuff via @WyreDavies. Interesting side note: Use of CS in war is prohibited under the terms of the 1997 Chemical Weapons Convention, signed by all but five nations. These five nations are therefore unhindered by restrictions on the use of CS gas: Angola, Egypt, North Korea, Somalia, and Syria.

All RCAs cause some form of eye irritation involving lacrimation and blepharospasm, which causes the eyes to close temporarily, rendering victims unable to see and dramatically reducing their ability to resist. PS, CN , CS, CR , DM, and OC also cause irritation to airways resulting in coughing, shortness of breath, and retching or vomiting. DM in effective doses causes significant vomiting with resulting mental depression and malaise. These agents cause some degree of pain sensation.

The reflex most associated with death from the inhalation exposure of the irritants is the Kratschmer reflex, as the immediate response of cessation of respiration. The response is a protective reflex or defense mechanism to prevent or reduce the amount of noxious chemical reaching the lower respiratory tract and maintain homeostasis. During cessation of respiration, blood levels of carbon dioxide increase and drive the respiratory center to restart breathing. Individuals with compromised immune systems, nervous system depression as a result of alcohol or illicit drug consumption, or a combination of these, may not be able to restart respiration and die from asphyxia.

Table comparing different types

Use this table to help determine the most likely agent that you have been exposed to.

The effects from RCAs are typically self-limiting, and discomfort is reduced within 30 minutes upon exiting a contaminated area. Usually no medical treatment is necessary, particularly if the agent is used in an open area and the dose is minimized.

Injury may range from skin and eye irritation to, in rare cases, injuries sustained from exploding dispensing munitions, delayed transient pulmonary syndromes, or delayed pulmonary edema requiring hospital admission.

Personal Protection

Short-term protection can be provided by dry clothing that covers the arms and legs, because sweat allows dry agents to adhere to the skin. The standard protective mask will adequately protect against the inhalation of RCA particles and vapors. CS1, CS2, or CR, exposure in large quantities requires protective clothing, mask, and gloves that cover all exposed skin areas should be worn.

Decontamination

Decontamination is important to reduce injury and continued exposure from agent on the skin, hair, and clothing. This is particularly important for those in contact with RCAs in enclosed areas for long periods of time, such as individuals running mask confidence training who are in the chamber repeatedly throughout a single day. Large amount of exposure to CS has resulted in erythema (red skin), minor skin burns, and blistering on the neck, arms, and other areas that were not continuously protected by a mask or clothing.

If unable to wear adequate dermal protection during exposure one MUST shower immediately with soap and water as soon as they return home.

When dry agents (CS, CR, CN, and DM) are dispensed in the open air in limited quantities, all that is needed to remove the agent, particularly when protective clothing is worn, is brisk movement: flapping the arms and rubbing the hair in a breeze or standing in front of a large fan. This will disperse most of the particles from the clothing and hair.

The mask should be worn during this process to insure that particles blown from other people performing the same procedure upwind are not inhaled. However, agent particles adhere to sweaty skin, so completely effective decontamination requires clothing removal followed by thorough washing of exposed skin and hair. Contaminated clothing should be removed and if laundered, cold water should be used to reduce vaporization of the agent.

Soap and water are an effective decontaminant for RCAs; they will not neutralize the agent but will wash it away. Water should be used in copious amounts. Soap helps loosen the dry particles and remove them adequately from the skin surface.

CR, CN and DM hydrolyze very slowly in water, even when alkali is present. Because these agents do not decompose in water, washing with soap and water will only remove them from surfaces. Run-off may produce irritation if it gets into the eyes, so the eyes should be closed and head lowered during decontamination (if the agent is not already in the eyes). Environmental contamination from these agents may be persistent and difficult to remove. CS is insoluble in water but will hydrolyze in water at a pH of 7, with a half-life of approximately 15 minutes at room temperature, and extremely rapidly in alkaline solution with a pH of 9, with a half-life of about 1 minute.

Decontamination solutions used on human skin should not be caustic to the skin. A solution containing 6% sodium bicarbonate, 3% sodium carbonate, and 1% benzalkonium chloride was found to bring prompt relief of symptoms and to hydrolyze CS. No form of hypochlorite should ever be used to decontaminate CS or other RCAs because it can react with CS to produce more toxic chemical byproducts and will further irritate tissues. Applying water or soap and water to skin exposed to CS or OC but decontaminated may result in a transient worsening of the burning sensation, which should dissipate with continued water flushing. PS liquid can also be decontaminated with soap and water, and clothing, which can trap vapor, should be removed.

Water in limited quantities increases the pain symptoms from OC, which has a water solubility of 0.090 g/L at 37° C. Without decontamination, OC symptoms should dissipate over time as the body’s substance P is diminished. OC resin can also be decontaminated with copious amounts of water, liquid soap and water, baby shampoo, alcohol, or cold milk. OC in the eyes can be decontaminated with copious water flushing, but symptoms may not dissipate for 10 minutes.

A compress of cold milk, ice water, or snow can help reduce the burning sensation once the individual has been decontaminated. Substances with high fat content, such as whipped cream or ice cream, also aid in decontamination and help reduce pain. Although OC is soluble in vegetable oil and other hydrocarbons, and such solutions can more easily be washed off the skin, hydrocarbons must not be used with solutions of OC and other RCAs such as CN.

The following is a list of commercially available products in the United States (I will update the list for Egypt – please use a Google search).

• Sudecon Decontamination Wipes (Fox Labs International, Clinton Township, Mich);
• Bio Shield towelettes (Bio Shield, Inc, Raleigh, NC) or Cool It!
• Wipes and spray (Defense Technology, Casper, Wyo); claim to help decontaminate and reduce pain in people exposed to pepper sprays and other RCAs.

Disclaimer