Riot-control agents, also called lacrimators (“tear gas”), include several compounds, the most important of which are CS (o-chlorobenzylidene malononitrile), CN (1-chloroacetophenone, also marketed as Mace), and OC (oleoresin capsicum, or pepper spray) All three are solids and are typically dispersed as an aerosol of fine particles (e.g., smokes) or droplets (e.g., sprays) These agents are widely available, cause significant incapacitating effects in closed spaces, and could conceivably be used in a terrorist attack CS and CN generate bradykinins leading to pain without significant tissue injury; OC binds to VR1 (TRPV1) receptors on sensory neurons and causes the release of substance P, which leads to neurogenic inflammation with vasodilation, hyperemia, and plasma extravasation as well as pain All these agents can cause transient ocular burning sensation, tearing, blepharospasm, and photophobia; irritation of the nose, throat, and upper airway; and skin burning, erythema, and sometimes vesication A few riot-control agents, such as Adamsite (DM), are referred to as vomiting agents because they cause pronounced vomiting in addition to delayed-onset irritation of the eyes and the upper airway Most victims under usual circumstances of exposure become symptomatic within seconds from the traditional lacrimating agents (irritation after exposure to DM may take up to 20 minutes to develop) but remain so for only 20 to 60 minutes However, high concentrations in closed spaces or after discharge of agent close to the victim’s face have been associated with serious medical complications, including severe ocular toxicity, dermal burns, and pulmonary failure A few lethal cases have been described in which death was caused by severe tracheobronchitis with pseudomembrane formation and pulmonary edema Management includes careful ocular and dermal decontamination The skin should be washed with soap and water, although this may cause transient increased pain Hypochlorite solution should not be used because it may exacerbate dermal burns via the creation of toxic by-products The eyes should be thoroughly irrigated after a single dose of topical anesthetic Respiratory complications must be managed supportively, as previously described for mustard and pulmonary-agent toxicity Because severe respiratory effects may not manifest for 12 to 24 hours, patients with dyspnea or any objective findings should probably be observed in the hospital Severe respiratory complications from exposure to riot-control agents have been described in at least two young infants, one of whom was in a house into which CS was sprayed A canister of pepper spray was accidentally discharged directly into the face of the other infant Both survived with prolonged care, the latter requiring ventilatory support, including days of extracorporeal membrane oxygenation A few cases