Tear gas is marketed as a non-lethal crowd control agent -- a chemical irritant that disperses crowds and then dissipates without lasting harm. The medical literature tells a different story [1].

CS gas, the primary compound in most tear gas, can trigger coughing, airway inflammation, reduced lung function, and pulmonary edema -- fluid leaking into the lungs that can lead to infection and chronic respiratory disease [2]. A single exposure can produce effects lasting up to two weeks, according to research published in American Thoracic Society journals [3]. Repeated exposure multiplies the risk.

Studies tracking exposed populations 16 to 20 years after incidents found chronic obstructive pulmonary disease in 35% of subjects and bronchiectasis in 32.5% [4]. Skin allergies, ocular injuries, and psychological distress round out the long-term profile [5]. The University of Minnesota found that conclusions about CS gas safety in vulnerable populations -- people with asthma, high blood pressure, or children -- rest on studies too small to support those claims [6].

Children face disproportionate risk. Their smaller airways, higher breathing rates, and time spent closer to the ground -- where heavier chemical agents concentrate -- amplify exposure [7]. MinnPost reported in February that federal agents have repeatedly deployed tear gas near schools with virtually no paediatric health data to guide policy [7].

The gap between the "non-lethal" label and the medical record is widening as deployment increases. The agents do not kill directly. They leave something else behind.

-- NORA WHITFIELD, Chicago