Phosgene chloride primarily causes which of the following?

Phosgene chloride is a highly toxic chemical known primarily for its effects on the respiratory system. When inhaled, it can lead to choking sensations and serious respiratory complications, including pulmonary edema, which occurs due to damage to the alveolar lining in the lungs. This damage can manifest as coughing, choking, and difficulty breathing, making respiratory distress the most notable and dangerous consequence of exposure to phosgene chloride.

The other options, while relevant to other types of toxic exposure, are not the primary effects associated with phosgene chloride. Skin burns are more typically related to corrosive agents, nervous system paralysis is associated with neurotoxic substances, and severe headaches can arise from a variety of environmental exposures but are not specific indicators of phosgene chloride toxicity. Understanding the primary effects of toxic substances is crucial for effective assessment and treatment in clinical settings.