Tear gas and its effects

Tear gas refers to a group of chemical irritants used primarily for crowd control, riot suppression, and self-defence. Despite the term “gas,” these agents are usually aerosols—fine particles or droplets dispersed into the air—designed to affect the eyes, respiratory tract, and skin, causing temporary pain and incapacitation. Tear gas is classified as a non-lethal weapon, although its misuse or exposure in confined spaces can lead to serious health risks.

Composition and Types

Tear gas encompasses several chemical compounds, the most common of which include:

• CS (2-chlorobenzalmalononitrile): The most widely used form, known for its strong irritant effects and quick dispersal.
• CN (chloroacetophenone): An older form, once common in police use and personal defence sprays, though less favoured due to its higher toxicity.
• CR (dibenzoxazepine): A more potent and long-lasting compound, effective at lower concentrations.
• OC (oleoresin capsicum): Commonly known as pepper spray, derived from natural capsaicin found in chilli peppers.

These substances are typically dispersed through hand grenades, canisters, or sprays that release the irritant into the air as a fine mist or vapour.

Mechanism of Action

Tear gas agents act primarily on the sensory nerves of the eyes, nose, mouth, and skin. When the chemical particles contact moist tissues, they react with mucous membranes, producing inflammation and irritation. The compounds stimulate pain receptors, especially the TRPA1 and TRPV1 ion channels, which are responsible for the burning sensation.
Upon inhalation, these chemicals irritate the upper respiratory tract, causing coughing, choking, and difficulty breathing. The irritant’s volatile nature ensures rapid onset of symptoms, which typically subside once the individual moves to fresh air.

Immediate Physiological Effects

Exposure to tear gas induces a predictable set of physiological responses:

• Ocular Effects: Intense burning, tearing, blurred vision, and involuntary eye closure (blepharospasm).
• Respiratory Effects: Coughing, choking, shortness of breath, chest tightness, and throat irritation.
• Dermal Effects: Burning, redness, itching, and, in severe cases, blistering or chemical burns.
• Gastrointestinal Effects: Nausea and vomiting may occur, especially with heavy exposure.

These effects are generally temporary, lasting from 15 minutes to a few hours, depending on concentration, exposure time, and environmental conditions.

Health Risks and Complications

While tear gas is labelled as non-lethal, serious health complications can arise from improper use or prolonged exposure:

• Respiratory distress: Individuals with asthma, chronic obstructive pulmonary disease (COPD), or other lung conditions may experience severe bronchospasm or respiratory failure.
• Ocular injury: High concentrations or close-range exposure can cause corneal damage or vision impairment.
• Dermal burns: Direct contact with canisters or residue can result in chemical burns, especially when skin is moist or sweat-covered.
• Psychological stress: Prolonged exposure during conflict situations can cause panic, disorientation, or trauma-related symptoms.

Deaths are rare but have occurred when tear gas has been used in enclosed areas, where the concentration of irritants becomes dangerously high and oxygen levels are reduced.

Environmental and Chemical Behaviour

Tear gas compounds are typically solid at room temperature and dispersed as aerosols or vapours. They degrade slowly in the environment, especially on soil or clothing, and can remain active for several hours if ventilation is poor. Rain or high humidity can increase persistence, while strong winds can rapidly dilute the chemicals.
Residues on surfaces can pose secondary exposure risks if not properly cleaned. Decontamination usually involves washing with large amounts of water, soap, or alkaline solutions to neutralise the chemical agents.

Medical Management and First Aid

The standard treatment for tear gas exposure is removal from the contaminated area and thorough decontamination. Recommended steps include:

1. Move to fresh air immediately to reduce inhalation.
2. Avoid rubbing eyes or skin, as this may worsen irritation.
3. Rinse eyes with clean water or saline for at least 10–15 minutes.
4. Remove contaminated clothing carefully to prevent spreading particles.
5. Wash affected skin with mild soap and water to remove residue.
6. Seek medical attention if symptoms persist or if respiratory distress occurs.

In severe cases, particularly involving respiratory distress or corneal injury, hospitalisation and supportive care may be necessary.

Legal and Ethical Context

Under the Chemical Weapons Convention (CWC) of 1993, the use of tear gas in warfare is prohibited. However, it remains legal for domestic law enforcement purposes, including riot control and personal protection. This distinction has generated ongoing ethical debate, as critics argue that the effects of tear gas can be severe and potentially lethal in confined or mismanaged conditions.
Human rights organisations have frequently called for stricter regulation of tear gas deployment, citing cases of misuse leading to mass injuries and fatalities. Concerns also extend to environmental contamination and long-term respiratory effects among exposed populations.

Applications in Civil and Military Contexts

Tear gas is primarily deployed by:

• Police and security forces for crowd dispersal and riot control.
• Military units for training exercises in chemical defence.
• Civilians in the form of pepper sprays for self-defence.

Delivery mechanisms include handheld sprays, grenade-style canisters, and projectile launchers. Some systems are designed to disperse the agent over wide areas, while others target individuals directly.

Advantages and Limitations

Advantages:

• Provides a non-lethal method for dispersing crowds or incapacitating individuals temporarily.
• Rapid onset and short duration make it manageable for controlled use.
• Cost-effective and easy to deploy with minimal equipment.

Limitations:

• Can cause unintended injuries or fatalities in high concentrations.
• Effectiveness varies with weather conditions such as wind and humidity.
• Risk of misuse, especially in enclosed or densely populated areas.
• Psychological and ethical concerns regarding its use against civilians.