Initial effects after mild to moderate exposures to chlorine include ocular and nasal irritation, followed by cough, and progressing to a choking sensation and substernal chest tightness Bronchospasm often occurs, especially in patients with a history of reactive airway disease Pulmonary edema may develop within 30 minutes to hours depending on the severity of exposure Mild to moderate exposures to phosgene may be initially asymptomatic with only the perception of a pleasant odor of newly mown hay Thus, lung-exposure time may be significant before victims remove themselves from the affected area Pulmonary edema occurs after a considerable delay, typically to hours, but up to 24 hours after low concentration exposures In these cases, delayed-onset shortness of breath or chest tightness precedes objective clinical or radiologic findings With high concentration exposures, early lacrimation may be followed by cough, dyspnea, and pulmonary edema The pulmonary edema may be so severe as to result in hypotension from hypovolemia The onset of shortness of breath or chest tightness within the first hours of exposure to phosgene portends the eventual development of massive pulmonary edema and a grave prognosis Management of exposure to pulmonary agents is primarily supportive Removal to fresh air generally suffices for decontamination Careful attention to control of pulmonary secretions, bronchospasm, and pulmonary edema as well as to aggressive treatment of secondary bacterial infection (often occurring to days after exposure) is required Animal studies suggest a modest benefit of steroid therapy in mitigating lung injury after chlorine inhalation; thus steroids may be considered for patients with chlorine exposure, especially as an adjunct to bronchodilators In addition, some symptomatic relief has also been reported for chlorine exposure with nebulized 3.75% sodium bicarbonate therapy, but the impact of this regimen on pulmonary damage is unknown Cyanide Compounds containing the cyanide ion (CN− ) have a long history as favored agents for homicide and suicide, but their efficacy as CWAs is limited by their volatility in open air and by their flammability However, if released nonexplosively in a crowded, closed room, they could have devastating effects Chemical agents containing cyanide include the liquids hydrocyanic acid (hydrogen cyanide, HCN; NATO Code AC) and cyanogen chloride (ClCN; NATO code CK), both of which rapidly vaporize after release Toxicology Some cyanide is normally present in human tissues and several pathways exist for its metabolism For example, cyanide reacts reversibly with metals such as ferric