Tear gas is used throughout the world as a form of crowd control. Hong Kong, Bahrain, and Iran deploy it against their citizens with regularity, and the police in more than one hundred United States cities released it during protests last summer. Tear gas is portrayed as safe, but it can cause devastating health effects, especially for vulnerable populations.
Tear gas is a term that refers to a group of chemicals that react with sensory nerve receptors, causing instant irritation to the skin, eyes, and mucous membranes. This irritation is felt as pain, and it can cause symptoms such as coughing, difficulty breathing, skin irritation, twitching near the eyes, vomiting, and of course, the production of tears. These symptoms typically fade within a few hours.
Common tear gas chemicals are not actually gases; they’re solids, but they can be aerosolized by explosive canisters or delivered as a spray. Tear gas is designed to be deployed in a large area with open ventilation, ensuring minimal exposure to the chemicals. If it’s administered in high concentrations in small spaces, it can be lethal. Where military forces are engaged in war, any usage of tear gas is banned by the 1993 International Chemical Weapons Convention. However, some countries, including the United States, have approved its use for riot and crowd control of citizens.
While tear gas is generally less lethal than other, more violent crowd control methods, that does not mean that it is completely safe. Data from several countries indicate that exposure to tear gas can cause miscarriages. In fact, Chile once suspended the use of tear gas out of concern for preborn humans. Young children are even more vulnerable to the impact of tear gas; for example, a child highlighted in a study from 1989 was hospitalized for a month with pneumonitis after tear gas was fired into their home.
People of any age with chronic health conditions are also likely to be at an increased risk of complications from tear gas exposure. As a 2016 article from the Annals of the New York Academy of Sciences states, “Individuals suffering from asthma or reactive airways disease could be at greater risk for more serious adverse effects from tear gas exposure...” Seemingly unrelated conditions can be impacted as well. The article goes on to say that “other populations besides those with underlying respiratory conditions may also be at a greater susceptibility to harm from [riot control agents]. The British Department of Health and other sources reported that individuals with hypertension or cardiovascular disease, as well as those taking neuroleptic medications, may be more susceptible to [tear gas]...” Unfortunately, there’s insufficient research about the effects of tear gases on vulnerable populations. One of the most commonly-cited safety studies only included 35 healthy male volunteers; no women, children, elderly, or subjects with chronic medical conditions were included.
Even for adults without medical conditions, the deployment of tear gas can be dangerous. Because these chemicals are frequently deployed via pyrotechnic canisters, there’s a risk of harm from the explosives that deliver it. People have died as a result of injuries sustained from tear gas canisters, while others have sustained serious injuries. If the gas is deployed in an unsuitable environment, the dosage can be poisonous.
And in the current setting of a global pandemic, the use of tear gas poses an additional threat. Many protestors over the last year gathered in socially distanced outdoor settings with masks to reduce the risk of spreading COVID-19. But it’s hard to maintain social distance when fleeing from a cloud of tear gas, and it’s challenging to keep a mask on when the gas is making it difficult to breathe. Irritation to the mucous membranes increases mucus production and can trigger coughing and sneezing, which spread more germs. Exposure to tear gas can also make people more susceptible to respiratory illnesses. Because COVID-19 is still so new, there is no data that addresses whether or not tear gas might accelerate its spread. But based on what we know already, it’s clear that the use of tear gas may increase the general risk of infections.
While tear gas is certainly preferable over other, more violent methods of crowd control, its use does not come without risks. Even in the best of circumstances, tear gas can be detrimental to the health of those who are exposed to it, especially those with certain risk factors. Assuming it’s always safe can have deadly consequences. We need to gather more data and re-evaluate the use of tear gas.