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Tear gas is not a single product, but can refer to any of at least 15 different chemical compounds that irritate the mucous membranes. This causes tearing, coughing, sneezing, pain and temporary blindness.
Most of these compounds have been developed in laboratories, but they can include natural chemicals, such as a sulfur compound found in onions.
The most commonly used in the United States are designed CS, CR and CN (also known by the brand name Mace).
The most popular form used by police is the CS variety. This takes its name from the initials of the two researchers who developed the agent in 1928.
CS (and most varieties of tear gas) is actually not a gas at room temperature. It is a mixture of a volatile solvent and a solid. The solid is pulverized into a fine powder and aerosolized to produce a "cloud" of the chemical into the air, which will then be inhaled, contacting the nose, mouth, eyes, throat and lungs of the person targeted.
In some situations, an aerosol is produced by heating the CS with hot gases or by other means.
The CN variety is widely available and works very effectively at close range. However, it does not disperse into larger areas as rapidly as CS. It is dispersed along with an oil or solvent, causing it to stick to the skin or other areas of the body.
CR produces more powerful effects than CS. It is also less toxic from ingestion or dermal exposure. However, it is a possible carcinogen. For this reason it is less widely used that the first two varieties discussed.
Like CS, CR is a solid at room temperature. It is a pale yellow solid that is made into a fine powder, suspended in a propylene glycol-based liquid and dispersed into the air. CR can stay active on surfaces for two months.
Knowing the specific make up of the tear gas you are dealing with can help with the cleanup, but each can be treated in a similar manner.
The need for personal protection equipment (PPE) should be obvious. A full-face respirator is advised. Use a respirator for organic vapors, along with a dust filter. Tear gas, especially the CR variety, can be irritating or painful on damp skin. Protect exposed skin with a hazard suit.
Remove as much of the residue as possible by vacuuming. Because the powder is so fine, an ordinary vacuum will allow the dust to pass through the filters and redistribute it into the air. Therefore, use a ULPA or HEPA vacuum system. Brushes can also spread the powder.
A truckmount with a wet misting option in the vacuum line can also be used. Be sure the vacuum hose extends outside the building with no air leaks. Gaps around cuffs or other breaks in the hose can result in tear gas getting into the environment you are trying to clean. It is wise to make sure the truckmounts exhaust is directed away from people.
Large volumes of water help to neutralize and flush out CS tear gas, but they can make the effect of CR worse. Double check your personal protective equipment when you begin using water.
An alkaline pre-spray or hard surface cleaning solution that includes surfactants to aid in penetration is the basic cleaning solution for tear gas. Because the tear gas usually includes solvents, a citrus solvent or a volatile dry solvent added to your cleaning solution aids when cleaning carpet, upholstery and hard surfaces. Use plenty of water to flush thoroughly, in particular when dealing with CS.
Including sodium bisulfite (liquid) or adding sodium metabisulfite to your alkaline cleaning solution improves the removal of CS. Several formulated coffee stain removers used in our industry contain sodium metabisulfite. Adding about one-half ounce to each gallon of ready-to-use cleaning solution will likely be sufficient for most situations. Caution! Sodium bisulfite is a reducing agent with a strong, unpleasant odor. It has the potential to remove or lighten colors on some surfaces. Special precautions including good ventilation must be taken if using sodium bisulfite for more than spot removal situations.
Contents may be moved outside and cleaned on a downdraft table, or immersed in a water-based alkaline cleaning solution.
Finish the job with ventilation and direct spray application of a deodorizer for severe odors.
Scott Warrington has more than 40 years of experience in the carpet cleaning industry and related fields. He serves as the technical support specialist for Bridgepoint Systems and Interlink Supply. He can be contacted at email@example.com.