Chlorine is a highly reactive gas that is used in large quantities throughout modern society. Accidental release of chlorine gas with exposure of large numbers of people is a constant threat to urban areas. The toxicity of chlorine is related almost entirely to effects in the respiratory system. The treatment of victims exposed to chlorine gas is mainly symptomatic including supplemental oxygen and antitussive medication. Administration of nebulized β2‐agonists is supported by recent experimental studies, and early treatment with inhalational or systemic corticosteroids is supported by case reports and experimental data. Systematic experimental studies and pre‐arranged treatment protocols are needed to advance the evidence base of therapy for chlorine gas lung injury.