Yes, you can die from tear gas, though it is rare. Deaths have occurred through three main pathways: high-concentration exposure in enclosed spaces, blunt trauma from the canisters themselves, and severe reactions in people with pre-existing conditions like asthma. Tear gas is classified as a “less-than-lethal” weapon because the dose needed to kill is many times higher than the dose needed to incapacitate, but that label obscures real risks that depend heavily on how and where the gas is used.
How Tear Gas Affects the Body
All common tear gas agents, including CS, CN, and CR, work by activating the same pain receptor on nerve cells called TRPA1. This receptor normally functions as a chemical danger alarm, detecting irritants and triggering protective reflexes like tearing, coughing, and eye closure. Tear gas essentially hijacks this system, forcing it into overdrive.
When the gas reaches the lungs, TRPA1 activation triggers the release of inflammatory signaling molecules that cause airway constriction, mucus production, and swelling. In the respiratory tract, this can progress to fluid buildup in the lungs (pulmonary edema), breathing failure, and in extreme cases, respiratory arrest. Animal studies have also shown that this same receptor plays a role in triggering irregular heartbeats, suggesting tear gas exposure could disrupt cardiovascular function as well.
Deaths From Chemical Exposure
Fatal chemical exposure typically happens when tear gas is deployed indoors or in poorly ventilated spaces, where concentrations can climb far beyond what someone would encounter outdoors. In Bahrain, a man died of respiratory arrest after CS gas was fired directly into his home. In the United States, a case of fatal airway destruction (acute necrotising laryngotracheobronchitis) was also linked to confined-space exposure. These cases share a common thread: the victim could not escape the gas, and the concentration overwhelmed the body’s ability to cope.
No exact lethal concentration has been established for humans. Researchers at the National Research Council found no human lethality data sufficient to set a precise threshold. What is known comes largely from animal studies and case reports, which consistently point to enclosed environments as the critical danger factor.
Older Tear Gas Agents Are More Dangerous
Not all tear gas formulations carry the same risk. CN (chloroacetophenone), the older compound used before CS became standard, is the most toxic of the common tear gases. It has been linked to at least five deaths from lung damage and suffocation. CS (chlorobenzalmalononitrile) is ten times more effective as an irritant, meaning less is needed to cause pain and incapacitation, but it is less toxic to the body’s organs overall. CS and CR, the newer agents, are considered to have a larger safety margin between an effective dose and a lethal one. Still, “larger safety margin” does not mean zero risk, especially when deployment conditions are uncontrolled.
Deaths From Canister Impact
The gas itself is not the only lethal risk. Tear gas canisters are heavy metal projectiles launched at high velocity, and when they strike the head, they can cause devastating injuries. A study from a neurosurgery hospital in Baghdad reviewed 41 patients admitted with tear gas canister head injuries during the 2019 protests. Of those, 10 had penetrating head wounds. Every single one of those 10 patients died within one to three days of admission, a 100% in-hospital mortality rate for penetrating injuries.
During protests in Beirut between 2019 and 2020, launched canisters caused skull fractures, facial fractures, and brain hemorrhages. In one widely documented 2018 case, an entire CS canister penetrated the skull of a 27-year-old Iraqi man, lodging in his brain. He died shortly after reaching the hospital. These injuries tend to occur when canisters are fired directly at people rather than lobbed in an arc as intended, particularly in densely populated areas.
Who Faces the Highest Risk
Certain people are significantly more vulnerable to serious or fatal outcomes. People with asthma experience more severe chest symptoms after exposure, and there are documented deaths resulting from the combination of asthma and tear gas. One postmortem examination of a person who had been sprayed repeatedly with pepper spray revealed severe lung tissue destruction, with the cause of death attributed to a sudden, extreme constriction of the airways likely triggered by the chemical irritant. People with high blood pressure also show a greater and more prolonged spike in blood pressure following CS exposure compared to those without hypertension.
Children face elevated risk for straightforward physiological reasons. A child’s smaller body size means a higher relative dose of any airborne chemical. Children also breathe more rapidly than adults, pulling in more gas per minute relative to their lung capacity. Their cardiovascular systems are less equipped to handle the stress response that tear gas provokes. These factors combine to magnify the harm of an exposure that might be tolerable for a healthy adult.
Long-Term Lung Damage
Even when tear gas exposure does not kill immediately, it can cause lasting respiratory problems. A study of 34 young adults exposed to CS gas in an enclosed coach found that months later, five still had respiratory symptoms. Two had worsening asthma, two had reduced ability to exercise, and one suffered from persistent coughing fits during physical activity, all assessed eight to ten months after a single exposure event. A larger analysis of 93 cases found patterns of chronic respiratory effects in people who had been heavily exposed.
Whether these long-term effects could eventually contribute to premature death is harder to pin down. Research on the chronic consequences of tear gas remains limited, a gap that researchers at the University of Minnesota have specifically flagged as a concern given how widely these agents are used worldwide.
Why It Is Banned in War but Allowed on Civilians
Tear gas occupies a peculiar legal space. The 1925 Geneva Protocol prohibits the use of chemical weapons in warfare, and most nations now interpret this ban as covering tear gas. The reasoning is not that tear gas itself is considered a weapon of mass destruction, but that allowing any chemical agents on the battlefield creates a risk of escalation toward more lethal chemicals. As one diplomat argued during United Nations disarmament discussions, military use of tear gas should be distinguished from its use in domestic riot control, because the contexts carry fundamentally different escalation risks.
The result is that the same chemical agents banned on foreign battlefields are routinely deployed against civilian populations during protests and crowd control. This is legal under international law because the Chemical Weapons Convention specifically exempts domestic law enforcement use. The distinction matters because civilian crowds include exactly the populations most vulnerable to tear gas: children, elderly people, and those with asthma, heart conditions, or other chronic illnesses.