A pulmonary agent (or choking agent) is a chemical weapon agent designed to impede a victim's ability to breathe. They operate by causing a build-up of fluids in the lungs which then leads to suffocation. Exposure to the eyes and skin tend to be corrosive, causing blurred vision and severe deep burns. Inhalation of these agents cause burning of the throat, coughing, vomiting, headache, pain in chest, tightness in chest, and respiratory and circulatory failure. Examples of pulmonary agents include: